1995 Impala SS - Transmission Issues


LT1Silverhawk
01-04-2010, 01:45 PM
Hi All,

I’ve got two questions related to a transmission issue with my ’95 Impala.

The specs on the car are: 383 LT1, fully built 4L60E auto transmission, and a built rear end with 3.90 gears. I don’t have the specs or records on any of the builds as they were done by the previous owner who sold the car to a local shop after an accident.

Yesterday, I gunned the car from a slow start and then heard a loud bang. The car was no longer getting any power to the wheels. I brought the car to a safe stop, put the transmission into park, turned the engine off, and then restarted it. I shifted through the gears and found that the engine was revving fine but still no movement in any gear.

I’m a total rookie when it comes to transmissions but, between my neighbor and me, we think it is one of two things: the transmission is shot or the torque converter is damaged.

Second question is, should the transmission turn out to be no good, any ideas of a good replacement transmission? I’m considering a T56 swap but have not been able to find any posts on this site that discuss how to do it.

I must add that I am on a budget so if it turns out to be too much, I may have to just sell the car as is.

I had the car towed to a local shop for a diagnosis. In the mean time, I thought I’d try and pick the brains of all the smart folks here.

What do ya’ll think?

Thanks in advance for any help…

j cAT
01-04-2010, 07:10 PM
I would bring to a repair shop and have the tranny opened up and see exactly whats damaged..could be a simple part change that snaped like a pretzel.

since the tranny was working fine prior to this it should not need a rebuild..Also since it is possible that the tranny has non OEM parts it is possible this is the reason this bang suddenly occured..

post back with your findings..

LT1Silverhawk
01-04-2010, 07:27 PM
I would bring to a repair shop and have the tranny opened up and see exactly whats damaged..could be a simple part change that snaped like a pretzel.

since the tranny was working fine prior to this it should not need a rebuild..Also since it is possible that the tranny has non OEM parts it is possible this is the reason this bang suddenly occured..

post back with your findings..


I was hoping you’d respond j Cat!

Of course, all other help is more than welcome!

I am expecting a response from the shop this week.

Unfortunately, as much as I trust the shop, I don’t trust the transmission shop they contract with for transmission repairs. The reason I took it to them anyway is because I am hoping they will give me a good diagnosis while I look for a reputable repair shop.

Would it be a bad idea for a rookie like me to drop the transmission, open it up myself, and take pictures for reference before going to a shop? After dealing with the last transmission rebuild on my Camaro, I am super nervous about dealing with any shop at this point.

Thanks j Cat… your tips and insight are helpful as always…

maxwedge
01-04-2010, 07:46 PM
Unless you are very mechanical and have the proper tools and a lift, I would not suggest tackling this, plus you do not know what was done and being inexperienced you would not be able to determine what is original and what has been changed/modified.

LT1Silverhawk
01-04-2010, 07:57 PM
Unless you are very mechanical and have the proper tools and a lift, I would not suggest tackling this, plus you do not know what was done and being inexperienced you would not be able to determine what is original and what has been changed/modified.


Thank you MaxWedge, you make an excellent point there.

My mechanical abilities are very limited when it comes to engine and transmission removal and installation.

However, I do have access to several 2 ton jacks, jack stands, an engine hoist and a host of tools. I expect that if I can get a good shop manual, I should be able to remove the transmission properly and safely.

My intention is not to determine what happened, because I sure as heck would not know what to look for, as you pointed out. But what I do want to do is to remove the transmission, open it (if that will not damage anything) and take pictures to use for reference before handing the transmission off to a shop.

The reason for doing all this on my own is that my last transmission rebuild through a shop was a horrible experience and I am afraid I may have been screwed over pretty bad.

At least with pictures in my hand, I may be able to get better input from other people as well before making a decision.

I really wanna do this right the first time.

BTW, any thoughts on a good replacement transmission or a T56 swap?

maxwedge
01-05-2010, 08:52 AM
Remember to get it high enough for the bell housing to clear the frame, aslo some jacking device to hold and roll the trans out, I would also suggest a trans manual from atsg.com

LT1Silverhawk
01-05-2010, 11:43 AM
Remember to get it high enough for the bell housing to clear the frame, aslo some jacking device to hold and roll the trans out,

I was thinking of buying a transmission jack but I think the local Harbor Freight carries adapters for regular floor jacks.

These are the two that I found:

2-ton jack adapter http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=39152 (http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=39152)

3-ton jack adapter http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95640 (http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95640)
 
 
 
I would also suggest a trans manual from atsg.com

Thanks! That’s a good site to know. The links below are to the books I feel best meets my needs. Apparently there is an “Update Version” that is required.

Original Guide: http://atsg.com/cart/products/4L60E-21-5.html (http://atsg.com/cart/products/4L60E-21-5.html)
 
Updated Guide: http://atsg.com/cart/products/4L60_E_4L65E_Update_Handbook-75-5.html (http://atsg.com/cart/products/4L60_E_4L65E_Update_Handbook-75-5.html)
 

Thanks for the continued help!

Now I just need to get over my fear and nervousness... :loser:

maxwedge
01-05-2010, 03:07 PM
The trans jack adapter works ok, but it makes very tough to roll the trans out from under the car as it requires more height, so watch out for that.

LT1Silverhawk
01-05-2010, 03:58 PM
The trans jack adapter works ok, but it makes very tough to roll the trans out from under the car as it requires more height, so watch out for that.

I’m glad you brought that up as I had not thought of it yet.

I realize there may be no way for anyone to know an answer to this without actually jacking up the car, but how high should the car be off the ground so the bell housing to properly clear the vehicle’s frame?

I think, with the jack stands I have now (standard Sears material), I can lift the car a little more than a foot off the ground. Otherwise I’ll try to get taller jack stands.

maxwedge
01-06-2010, 09:22 AM
You will need to get this up more than 12".

LT1Silverhawk
01-06-2010, 10:57 AM
You will need to get this up more than 12".



I think my floor jacks are good for about 2 feet of lift (standard Sears 3 ton). So I can get taller jack stands and get some good clearance. I guess the one thing to add to the height of the transmission's bellhousing is the height of the floor jack and adapter.


Just browsing the Harbor Freight site again and found:

3 ton jack stands (good for 16" clearance) http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=38846 (http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=38846)

6 ton jack stands (good for 24" clearance) http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=38847 (http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=38847)

MagicRat
01-06-2010, 11:27 AM
LT1, hold on for a moment.

Before you do this, consider a couple of points.

1. If you re and re your own transmission, then you are responsible for removing it again if there is a defect in the rebuild..... even if the rebuilder is at fault. This happened to me once. It's really annoying to re and re a second time due to no fault of my own.

If you send it to a mechanics shop for the re and re, then they are responsible for removing it again, at no cost to you, if there is a defect that needs fixing.

Have you ever removed a transmission before? If not then, without a hoist and a couple of buddies, its a bitch. It's easy to drop the trans and damage the housing and/or injure yourself. If you enjoy the challange of working on your own car, go ahead and do it. But otherwise, let the rebuilder do it.

2. I strongly suggest against disassembling your transmission. Unless you know about auto transmissions, diassembling one is like taking an alien spacecraft apart. Many of the components, their function and disassembly are completely unfamiliar. At the very least, you will need a good tramsissison rebuild manual to take it apart (Haynes makes one).

You will also need special circlip pliers and a unique transmission spring compressor to disassemble. Trust me, rebuilders hate getting a basket of parts. Parts can be lost of damaged during disassembly. You need to keep track of many many small parts. Some parts MUST be reassembled in the same order that they came apart. Even if you keep track of them, a rebuilder may not understand your system of keeping track of this stuff and screw it up. A rebuilder may blame you if something is lost or damaged, even though it may be their fault.


Also, the rebuilders ability to diagnose the fault is impeded because they cannot inspect the components in their as-found condition for things like end-play or tolerances.
Finally, there may be a warranty issue if you have done some disassembly on your own.
IMO if you want a good rebuild experience, look around for a reputable shop. Ask them for references and speak to some of their customers. Let them do the entire job, including removal. This makes determining the responsibility of repair and warranty coverage much, much easier.

LT1Silverhawk
01-06-2010, 02:35 PM
Before you do this, consider a couple of points.

1. If you re and re your own transmission, then you are responsible for removing it again if there is a defect in the rebuild..... even if the rebuilder is at fault. This happened to me once. It's really annoying to re and re a second time due to no fault of my own.

If you send it to a mechanics shop for the re and re, then they are responsible for removing it again, at no cost to you, if there is a defect that needs fixing.

Have you ever removed a transmission before? If not then, without a hoist and a couple of buddies, its a bitch. It's easy to drop the trans and damage the housing and/or injure yourself. If you enjoy the challange of working on your own car, go ahead and do it. But otherwise, let the rebuilder do it.


I completely agree with you on the whole r&r deal. I do enjoy the challenge of working on a car but my biggest concern is getting ripped off again on the rebuild.

So far, I personally have not been able to find any shop that I have a good feeling about. The last rebuild on my Camaro was shoddy and I would take the Impala back to the shop that originally built it up but (j cAT, you probably remember this from helping me out before with the oil burning issue) “The Shop’s” owner himself seems a bit shady.


Ok, side-story time…

Interestingly, the Camaro (1993 LT1, 4l60/700R4 transmission) that had the transmission rebuilt apparently had the same thing happen as my Impala, except with a different owner. The guy who sold me the Camaro said his brother driving on the freeway when, all of a sudden, he heard a bang (just like in the Impala), and the car was no longer getting power at the wheels.

When I took the Camaro in to my local trusted mechanic shop, they shipped it to a contractor who rebuilds transmission for them. They had nothing but high praise for this contractor: reliable work, 12 month / 12,000 mile no-questions-asked warranty.

The Contractor did not pick up the car for a good week.

After he took the car, the first thing The Contractor did was call back, saying the transmission was frozen and would he need another core for a rebuild for an additional $100. Not having any knowledge, I agreed to it.

The Contractor took his sweet time on the rebuild. As soon as I got it back, I noticed the car just wasn’t moving fast. Felt more like my friend’s V6.

So the shop sent it back and the transmission was “rebuilt” again. On the test drive, the good ‘ol Opti-Spark died.

After the Opti-Spark was replaced (which is another story in itself), we went for another test drive and still, the car felt week. I asked around and a local transmission rebuilder who happened to be at AutoZone said it was the wrong torque converter.

So, I took the car back to the shop and told them it seems like The Contractor used the wrong torque converter. They shipped it off again, informing The Contractor that I said there was an issue with the torque converter.

Again, the Contractor took his sweet time, sent the car back and this time, it felt powerful. But the transmission pan gasket went bad – twice. This was about a year ago this month.


I am continuing to ask around while waiting for an answer from my local shop where the car is presently sitting. I am considering going to local performance shop, Team C Performance. They tend to be on the pricey side about everything but also seem quite knowledgeable. But a coworker also recommended a family member who is ASE certified and is well-versed in GM vehicles. He is charging $400 ballpark for the labor if I provide the parts.




2. I strongly suggest against disassembling your transmission. Unless you know about auto transmissions, diassembling one is like taking an alien spacecraft apart. Many of the components, their function and disassembly are completely unfamiliar. At the very least, you will need a good tramsissison rebuild manual to take it apart (Haynes makes one).

Aside from the fact the auto transmissions shift automatically, have fluid, a filter, a pan and a torque converter, I don’t know a damn thing.

MaxWedge was very helpful in recommending ATSG for a good transmission manual for a through walk-through. A little research showed that there are some detailed DVDs available as well (How detailed? I don’t know).




You will also need special circlip pliers and a unique transmission spring compressor to disassemble. Trust me, rebuilders hate getting a basket of parts. Parts can be lost of damaged during disassembly. You need to keep track of many many small parts. Some parts MUST be reassembled in the same order that they came apart. Even if you keep track of them, a rebuilder may not understand your system of keeping track of this stuff and screw it up. A rebuilder may blame you if something is lost or damaged, even though it may be their fault.

Also, the rebuilders ability to diagnose the fault is impeded because they cannot inspect the components in their as-found condition for things like end-play or tolerances.
Finally, there may be a warranty issue if you have done some disassembly on your own.
IMO if you want a good rebuild experience, look around for a reputable shop. Ask them for references and speak to some of their customers. Let them do the entire job, including removal. This makes determining the responsibility of repair and warranty coverage much, much easier.

Again, good points.

I feel that if I can find someone who will give a correct diagnosis with no intention of ripping me off, I’ll be more than happy to let them deal with the entire process from beginning to the end.

However, from a "desire to learn perspective”, I may be better off going with my co-worker’s recommendation and be a small part of the process so I can at least observe what goes on in such a project.


As always, thanks for the continued help and support and letting me rant. I've learned quite a bit already...

You guys are awesome!

MagicRat
01-06-2010, 02:45 PM
Yes, that experience does seem to suck a bit. Have you considered a performance transmission from an on-line supplier, if there are no decent shops avaialble locally?

The reason why I ask is that a rebuild shop may charge you extra for replacing broken hard parts. If this is the case, you may be able to save a couple of bucks by getting a rebuilt transmission on exhange.... and its much faster, too.

The 700R4 / 4L60 series seem to have a couple of weak mechanical parts, such as the annulus (ring) gear in one of the planetary gear sets. These things break with a bang and cause you to lose all gears instantly. It happened to me, with a 700R4, and I just had a weak 305. And yes, I took my own transmission apart, with the thought of rebuilding it. When I found the ruined gearset, I just located a used 4L60 (not an 'E') for $150 and swapped it in.... much cheaper in the long run.

I think you can get aftermarket gear sets which are stronger than stock. Some on-line rebuilders may offer such upgraded parts in their transmissions.

LT1Silverhawk
01-06-2010, 03:24 PM
Yes, that experience does seem to suck a bit. Have you considered a performance transmission from an on-line supplier, if there are no decent shops avaialble locally?

The reason why I ask is that a rebuild shop may charge you extra for replacing broken hard parts. If this is the case, you may be able to save a couple of bucks by getting a rebuilt transmission on exhange.... and its much faster, too.

I have considered buying a performance transmission online but haven’t done any serious research just yet. As jcAT pointed out, it may just be a simple part and the entire transmission may not need to be replaced. So I am waiting to find out exactly what is wrong before I start looking around.

There are lots of local shops, but I am struggling to find one with an excellent reputation. In these economic times, many people seem to be cutting corners to make a quick buck.




The 700R4 / 4L60 series seem to have a couple of weak mechanical parts, such as the annulus (ring) gear in one of the planetary gear sets. These things break with a bang and cause you to lose all gears instantly. It happened to me, with a 700R4, and I just had a weak 305. And yes, I took my own transmission apart, with the thought of rebuilding it. When I found the ruined gearset, I just located a used 4L60 (not an 'E') for $150 and swapped it in.... much cheaper in the long run.

I think you can get aftermarket gear sets which are stronger than stock. Some on-line rebuilders may offer such upgraded parts in their transmissions.

It would be cheaper to find a used 4L40E and replace it bad one but I need one that can handle the stroker’s power. And therein lies one of my biggest challenges: finding the right combination of parts that reliably handle the power. I’ve seen several prepackaged kits from Trans-Go, TCI and B&M but don’t know which one to go with.

There is also PATC that seems to offer a pretty sold transmission:

http://www.transmissioncenter.net/4L60E.htm (http://www.transmissioncenter.net/4L60E.htm)


On a side note, the transmission in the Impala shifted pretty hard from 1 - 2, and 2 -3. "The Shop" owner said this was because the transmission was built a step below a racing transmission, hence the hard shifting. But this thing was a real back breaker. Daily stop and go pretty much killed my back to be point that I've considering selling the car. With this opportunity in hand, I'd like to able to modify it so it doesnt shift so hard under normal driving.

MagicRat
01-06-2010, 05:24 PM
I am not sure about the 4L60E, but back in the old days, it was easy to get a transmission to shift very firmly by changing the springs in the valve body. But a firm shifting transmission in not necessarily a stronger or better one.
Very firm shifts place excess strain on the gears, shafts and clutches of a transmission and, theoretically can lead to broken parts - parts which may live longer with softer shifts.

LT1Silverhawk
01-06-2010, 05:53 PM
I am not sure about the 4L60E, but back in the old days, it was easy to get a transmission to shift very firmly by changing the springs in the valve body. But a firm shifting transmission in not necessarily a stronger or better one.
Very firm shifts place excess strain on the gears, shafts and clutches of a transmission and, theoretically can lead to broken parts - parts which may live longer with softer shifts.

From what I’ve been told, the 4L60E is basically a 700R4 that shifts electronically, so perhaps the idea of changing the springs to modify the shift’s firmness may still apply.

And I must add that the shifts from the Impala’s transmission were super hard. I noticed the shifts weren’t as bad after I installed a 180 degree thermostat (the car did not have one; just a housing). Perhaps this allowed the transmission fluid to get to a proper heat level?

When I brought up the firmness of the shifts to “The Shop’s” owner, he told me that is how the transmission was supposed to shift. I never did fully believe him.

But the transmission did go on me out of nowhere. No signs of trouble before this incident.

j cAT
01-06-2010, 07:09 PM
From what I’ve been told, the 4L60E is basically a 700R4 that shifts electronically, so perhaps the idea of changing the springs to modify the shift’s firmness may still apply.

And I must add that the shifts from the Impala’s transmission were super hard. I noticed the shifts weren’t as bad after I installed a 180 degree thermostat (the car did not have one; just a housing). Perhaps this allowed the transmission fluid to get to a proper heat level?

When I brought up the firmness of the shifts to “The Shop’s” owner, he told me that is how the transmission was supposed to shift. I never did fully believe him.

But the transmission did go on me out of nowhere. No signs of trouble before this incident.
my 96 impala the tranny oem shifts very smooth...
the only vehicle I ever owned that had the harsh 1-2 upshift is the 84 camaro with the 700r4 tranny..I still have this vehicle ...since 84..never did like that shift...as mentioned its not good..had it checked out at a shop also back in 86 said they all shift that way and I found this correct..

LT1Silverhawk
01-06-2010, 07:20 PM
my 96 impala the tranny oem shifts very smooth...
the only vehicle I ever owned that had the harsh 1-2 upshift is the 84 camaro with the 700r4 tranny..I still have this vehicle ...since 84..never did like that shift...as mentioned its not good..had it checked out at a shop also back in 86 said they all shift that way and I found this correct..

Wow, a fellow Impala and an ’84 Camaro original owner! I’ve got an ’84 that is in project condition at the moment. Never worked on a carbureted car before so let’s see what I screw up. The last owner supposedly installed a 383 with a Powerglide with the intention of building a dragster. It cranks but it doesn’t fire up and I haven’t had a chance to find out why.

I would assume the stock transmission on Impalas do shift nice and smooth, which is another reason why their owners prefer them as their daily drivers. But the transmission in my car supposedly blew out once before when the 383 was installed.

Man, if I only had a way of showing you guys how crazy this car up shifted prior to going funky on me.

j cAT
01-06-2010, 07:30 PM
with the 4l60e that you have ..when the transmision slips the PCM /computer detects this...then it commands maximum transmission line pressure to reduce the slipage..on engine shut down this will reset...then will again repeat if the transmission slips..

maximum pressure equals a harsh shift...I had this occur on my 2000 silverado one time...it was about 6 below zero F out ...

LT1Silverhawk
01-06-2010, 07:48 PM
with the 4l60e that you have ..when the transmision slips the PCM /computer detects this...then it commands maximum transmission line pressure to reduce the slipage..on engine shut down this will reset...then will again repeat if the transmission slips..

maximum pressure equals a harsh shift...I had this occur on my 2000 silverado one time...it was about 6 below zero F out ...

I was told by “The Shop” owner that my transmission shifts off full-line pressure, which is why the transmission up shifted so hard.

So, if I understand this correctly, the PCM forces the transmission to shift off full-line pressure due a slippage it detects. Does this occur even with a reprogrammed PCM? Or I guess a better question is, would a reprogrammed PCM minimize the harshness of the up shift?

j cAT
01-06-2010, 08:15 PM
I was told by “The Shop” owner that my transmission shifts off full-line pressure, which is why the transmission up shifted so hard.

So, if I understand this correctly, the PCM forces the transmission to shift off full-line pressure due a slippage it detects. Does this occur even with a reprogrammed PCM? Or I guess a better question is, would a reprogrammed PCM minimize the harshness of the up shift?

yes it appears they programmed the pcm to max line pressure..this should not be set to this.. this can be changed with the proper equiptment..this stresses out the tranny as well as the u joints...not a comfortable ride..

with the use of mobil synthetic transmission fluid this transmission will normally shift very smooth and firm...the original dexron III was not up to this ...and this may be why this was programmed to the max line pressure to overcome the dexron III issues...

the synthetic fluid made a big improvement with my both 4l60 e trannys..

LT1Silverhawk
01-06-2010, 08:32 PM
yes it appears they programmed the pcm to max line pressure..this should not be set to this.. this can be changed with the proper equiptment..this stresses out the tranny as well as the u joints...not a comfortable ride..

with the use of mobil synthetic transmission fluid this transmission will normally shift very smooth and firm...the original dexron III was not up to this ...and this may be why this was programmed to the max line pressure to overcome the dexron III issues...

the synthetic fluid made a big improvement with my both 4l60 e trannys..

That is some interesting and very important information that I was not aware off.

I’ve always had a feeling that there was an issue with the programming of the PCM because “The Shop” owner told me the previous owner was constantly sending off the PCM to be reprogrammed somewhere on the east coast. And I thought it may have something to do with the shifting but didn’t realize it was these severe.

Also, I noticed that at high speeds, there was a constant booming noise echoing throughout the car. It started usually after about hitting 75 mph. It just went ‘boom boom boom’. I wonder if it was related to this.

Although im not sure if the original fluid in the transmission is Dexron III, I guess I should’ve check and replaced the fluid. Now I know what do next time. Do you think Mobil 1 Synthetic (which I'm a huge fan of) will make a significant difference in shifts in a performance-built transmission?

j cAT
01-07-2010, 04:38 PM
the boom noises I have no knowlege..I would post that after you get the transmission repaired to see if it is still there..

mobil synthetic is the tranny fluid I would use...with the tranny being repaired be sure they use the synthetic fluid...

dexron III is still available as I noticed it on the shelves of the auto part stores BUT there are no spec numbers on the bottle or where the fluid was made or who made it..............so this fluid should not be used in any thing..

have the PCM programed to restore the transmission operation to original..this may be difficult or easy if you can find a shop with the equiptment...I have never changed my pcm programing...years ago you could by a programer but not sure if those could change the tranny control...

LT1Silverhawk
01-07-2010, 05:18 PM
the boom noises I have no knowlege..I would post that after you get the transmission repaired to see if it is still there..
Yeah its really weird and probably annoys the passengers. Driveshaft-related?




mobil synthetic is the tranny fluid I would use...with the tranny being repaired be sure they use the synthetic fluid...

dexron III is still available as I noticed it on the shelves of the auto part stores BUT there are no spec numbers on the bottle or where the fluid was made or who made it..............so this fluid should not be used in any thing..
Ok, Mobil synthetic is added to the shopping list.

How about rear end gear oil? Do you recommend the same?




have the PCM programed to restore the transmission operation to original..this may be difficult or easy if you can find a shop with the equiptment...I have never changed my pcm programing...years ago you could by a programer but not sure if those could change the tranny control...
I know there is one programmer out there called the LT1 Edit, but it’s $1500 for one PCM and the user has to be pretty advanced in the mechanics of the car to use it. I think there are a few reputable local ones. Otherwise, PCM For Less seems to come up a lot on message boards with good reviews.

Since the transmission shifts electronically, I would assume it can be reprogrammed through the PCM.



Other updates:

After having talked to all of you guys and having some sense knocked into me, I have abandoned the idea of dropping the transmission myself.

I will be contacting my coworker’s cousin this weekend to see what can be done about my car. If he seems well-versed, I’ll pass the job to him and help him out so I can learn along the way. Sounds like the best way to kill two birds with one stone.

Also, any recommendations on performance rebuild kits and torque converters (should they be needed)? There are so many options out there I don’t know which one to go with. if you know of a good guide, that would be very helpful.

Thank you guys... :bigthumb:

j cAT
01-07-2010, 05:41 PM
[quote=LT1Silverhawk;6089330]

How about rear end gear oil? Do you recommend the same?

the rear diff, if the stock limited diff takes, 80-90wt gl5 hypoy C .
since 1996 I have used the castrol brand of this gear oil with the 4 oz of rear diff additive required for the clutches,,,,when doing this clean the rear diff out and use the proper diff cover gasket [DO NOT BLOCK THE DRAIN BACK HOLES]...these holes return oil from the rear wheel bearings.

LT1Silverhawk
01-07-2010, 05:51 PM
How about rear end gear oil? Do you recommend the same?

the rear diff, if the stock limited diff takes, 80-90wt gl5 hypoy C .
since 1996 I have used the castrol brand of this gear oil with the 4 oz of rear diff additive required for the clutches,,,,when doing this clean the rear diff out and use the proper diff cover gasket [DO NOT BLOCK THE DRAIN BACK HOLES]...these holes return oil from the rear wheel bearings.

The rearend was rebuilt with 3.90 gears. Im not sure what kind of oil is in there already.

Perhaps I'll give "The Shop" a call to see if they remember...

j cAT
01-08-2010, 09:57 AM
The rearend was rebuilt with 3.90 gears. Im not sure what kind of oil is in there already.

Perhaps I'll give "The Shop" a call to see if they remember...

I forgot that this has been changed out to the 3.90...do a search on this in the impalass forums as most likely this has been done by someone there.

LT1Silverhawk
01-12-2010, 05:54 PM
Hi All,


So, during the time between my last post and today, I’ve doing as much research as possible and found the following:



a. Local Performance Transmission Builders – nothing so far except a local performance auto parts store (Team C Performance) and coworker’s cousin who is a certified mechanic at a BMW dealership and works on GM cars for a hobby. He is estimating $400 in labor. Verdict: Best route if I want to learn how to rebuild a transmission and save some moola.


b. Rebuild Kits – found a few from several companies on Jegs and Summit but not sure which one to go with yet.


c. Harsh Shifting – can be eliminated to some extent by reprogramming the PCM.


d. Transmission Replacement – A guy in San Diego area has been advertising his expertise in LT1s and Impalas (over ten years) and works on these cars and builds performance-oriented LT1s. I gave him a call and he says he’s got a performance transmission with a TCI converter that was used for about 200 miles (the car was hit) for $1800. He also has a stock 4L60E transmission with 55,000 miles for $500. He says as long the car is not pushed, the stock transmission should hold up for a while until I am ready for a performance-oriented transmission. Verdict: The stock replacement is the cheapest route to take until I have enough money to put in the right transmission the first time (the second time around, of course). The car will keep moving in the mean time.


e. T-56 Swap – Someone created a booklet and posted it on the Impala SS forum that offers a complete walk through of the entire installation process. Can be done in a weekend with help. Verdict: Perhaps the most expensive and challenging option. But super cool and kind of rare.


f. 3.90: Gear Oil – haven’t found any information on that yet.


g. “Boom Boom” Noise – Possible vibrations from the driveshaft at high rpms.


Still haven’t heard anything from the shop where the car presently sits. I’ve been too busy to call. I’ll stop by on Friday to see what’s up but I’m not expecting any answers.

j cAT
01-12-2010, 05:58 PM
great info keep us updated.

the rear diff could be a locker type diff. see if you can pull numbers off the gears..

LT1Silverhawk
01-12-2010, 06:58 PM
great info keep us updated.

the rear diff could be a locker type diff. see if you can pull numbers off the gears..

Thanks!

How do I check the numbers?

j cAT
01-12-2010, 07:06 PM
Thanks!

How do I check the numbers?


there appears to be a few companies that supply gear sets that will fit this rear diff housing...most likely this is what occured in your vehicle..the gear set should have stamped numbers on it...locate these companies and ask where exactly you find this also what fluid to use...

with the rear diff cover removed there are pictures of the rear diff gear set on these web sites .....this also will help you identify the diff..also.

LT1Silverhawk
01-12-2010, 07:16 PM
there appears to be a few companies that supply gear sets that will fit this rear diff housing...most likely this is what occured in your vehicle..the gear set should have stamped numbers on it...locate these companies and ask where exactly you find this also what fluid to use...

with the rear diff cover removed there are pictures of the rear diff gear set on these web sites .....this also will help you identify the diff..also.

Ok, that sounds doable. As soon as I have access to the car (probably not for a nother few days or a week), I'll pop the cover and see what I find.

Thanks again!

LT1Silverhawk
02-25-2010, 08:50 PM
I thought it was time for an update on the transmission situation.

I got quite a few recommendations for some local performance transmission builders but haven’t managed to cough up the moolah yet.


However research into the following items continues…

a. Rebuild kits: I’ve only received one recommendation: http://www.700r4l60e.com/store/product.php?productid=330&cat=22&page=1 (http://www.700r4l60e.com/store/product.php?productid=330&cat=22&page=1)
b. What actually failed:
a. I haven’t been able to go to the shop where the car is parked and, they won’t touch it because they outsource their transmission work. I told them I was shopping around for the best transmission deal and would pay them to handle the removal and installation.
b. Lost a job this week so getting the transmission properly built is quite out of the question at the moment. I put the car up for sale but, if no decent offers come through, I have decided to swap in a stock engine, transmission and PCM from a ’95 9C1 to get the car back on the road again. There is a guy who selling this setup for $500 and I have a couple of friends to help me. Sounds like the cheapest way to go for now. I can pull whats in the car and rebuild it as time and money allow.

c. Some further research on the Impala SS Forums let me to the “Common Failures” thread and, based on the information listed, I have the situation narrowed down to the following scenarios:
i. “Loud bang, grinding sound, loss of all gears, and a binding driveshaft: snapped output shaft. Try to wiggle driveshaft - if more than 0.020" play, that's the sign. R&R.”
ii. “No movement in any gear: pump failure, or total loss of fluid. R&R, or refill pan and find the leak. If out of fluid, avoid running the engine until the trans is refilled to avoid pump damage. To check for pump failure, check fluid level with the engine off, then start the engine and recheck fluid level. If level does not go down when engine is running, the pump is broken.”
d. Additionally, I had a guy call me up after he saw my ad and it turned out he was a member of a local Impala club. After I described everything to him, he concluded that it may be the rear end. His suggestion was to raise the rear, put the transmission in neutral and see if the wheels spin freely. My friend and I did push the car a ways when it broke down so I figure it’s not the rear end.

LT1Silverhawk
11-14-2010, 09:19 PM
9 Months Later...


Well, since the last post, Ive done nothing but research everything about the transmission, shop around for good replacements, and finding the courage to tackle the job myself.



I finally jacked up the car a couple weekends ago, started the car, put the transmission in various gears and checked to see what happened.

Results:


Reverse: Wheels (http://www.automotiveforums.com/vbulletin/showthread.php?t=1054026#) would not move under acceleration. Wheels hard to move by hand.
Neutral: Wheels spun freely by hand.
OD: Wheels did not move under acceleration. Wheels hard to move by hand.
D: Wheels can very very barely move under hard acceleration. Wheels move fine by hand.
2nd: Same results as D.
1st: Same results as OD.
I find it safe to say that the rearend is not damaged.




So I've decided to tackle the removal and reinstallation job myself. A stock 4L60e out of a '95 9C1 with 97k miles on the clock will serve as a temporary fix.

The story continues in the thread linked below.


1995 Impala SS - Transmission Removal and Reinstallation

http://www.automotiveforums.com/vbulletin/showthread.php?t=1054026

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