95 Jimmy tranny problems...

[95xjsport]

I left work, came to a red light, light turned green, so I turned into the walmart parking lot, needed some cigarettes, there was an awful grinding noise from the truck and I have no gears, well I have reverse and one of the higher ones possibly 3rd of fourth. The truck gave me no warning at all. just went. is this common for these trucks? I was told it is a GM thing, if it is this will be my first and Last gm product.I'm going to a slavage yard tomorrow for a tranny, what years are compatabe with my truck? it is the 95 GMC Jimmy SLT with the V6 vortec engine and 4wd which dosn't work I need to know asap as we are leaving around 8ish tomorrow. my e-mail is [email protected] and my cell number is (570)404-0694

[blazes9395]

Basically, the '95 is very unique in that only a '95 tranny will work with the '95's. You mentioned its a SLT so it will be the CPI motor and that has a PWM control tranny. Your only other option is to rebuild what you have.

[95xjsport]

What a pain in the ass to put that damn thing in, what were they thinking when they designed half of that stuff? oh wait, I don;t think they were, lol. I got the new tranny almost in just need to put the transfer case back in, the cross member and exhaust system. I found a junk yard one for 450 with 60,000 miles. Thats it, there are no other ones in my area. I was told the gm trannys has problems with some valves and cooling therefore they don;t last as long. i was told they can be upgraded? Is this upgrade something that I can do or would I need to take it somewhere, I basically have my old tranny that I can mess around with. How bad are they to rebuild? Like you said previously it is 95 only. what is the difference between say a 94 or a 97? could I put one of the newer redesigned ones in? I believe 98 and newer? would it bolt up to my motor? I really do like this truck, I want it to last as long as possible, it is in really good shape, there is no rust or anything on it, the previous owner painted it prolly just months before I bought it so the paint is damn near perfect... Thanks in advance...

[blazes9395]

The difference between the 93-94 is the valve body, and the torque convertor apply, which uses a different valve body. The 95 is unique in that it uses a PWM (Pulse Width Modulated) apply strategy to lock the torque convertor up, the 93-94 electronic transmissions use a on/off apply for the torque convertor, and as a result, have a different valve body on them. The '96 up use a EC3 system (I think thats what its called), in that the torque convertor gradually applies as the transmission is shifting through its gears. the torque convertors are internally different too, so its a totally different system. It completely locks up at just about when 4th gear is reached, the '95 is a quick gradualy apply, and the 93-94 is a quick on/off apply(you will feel and hear it( engine RPM)). Also the 96 and up have different transmission cases alltogether, so it will not bolt up to the '95 engine. If you want to make that used tranny last longer, the updates to it is strongly advised. I don't know how comfortable you are with tranmissions, but if you are, pull the valve body, change the valve body to case spacer plate. If it hasn't been rebuilt, you will see why. The reason being is that a check ball has a tendenancy to go through the valve body plate, causing big problems (burning up the 3-4 clutches for one, also shift problems). All 4L60e's have this problem. Second update is using the Sonnax update to replace the TCC apply regulator valve. You will need to get it reamed though before you install the valve, again pretty much all the 4L60e's have this problem too. Also its a good idea to change the PWM solonoid too, if its original put a new one in, it will save you the possibility of having any common problems with this solonoid after.

Take a look here and see the common problems these transmissions have, and the updates that almost all tranny places use. I hope this gives you an idea. http://www.transmissionspecialty.com.../DM/4L60-E.htm

[95xjsport]

I'm not into taking them apart but, where can I get this updated valve body? It can't be too hard to replace, what if I were to swap to a newer motor?could I use my existing computer/ wiring harness? I really don;t want to put a tranny in every 20000 miles...

edit: could I put one of the older ones in? say 93-94 or did they have problems too?

[blazes9395]

Swapping the motor for a new one, is possible but you're asking for a lot of work, and potentially a lot of trouble. You would have to change the wire harness, and computer, or reflash your current one, either way, a lot of money and work. Go to a tranny shop with your valve body and ask them to ream the TTC regulator bore for you so you can install the update. Any competent shop will know what your talking about and charge you a small fee for doing it. the 93-94 will not work as just a bolt-up, it would need a '95 valve body, along with a '95 convertor clutch - same as just doing your '95. Hope this helps.

[95xjsport]

ok, all I would need it have reamed is the valve body? thats the part that kinda looks like a maze right??

[Blue Bowtie]

You would need more than a valve body. The method that the PCM used to actuate the valve is different than your '95.

FWIW - Hydramatic 4L60s are not a weak transmission. For several years, GM had trouble with the a couple of the supplied parts, namely the reaction sun shell (splined hubs stripping) and sometimes the reverse apply setup. The biggest enemies of any auto trans are maintenance neglect and heat. Regardless of the owner's manual's maintenance schedule for "normal" driving, use the "Severe Service" schedules for maintenance or change fluid and filter every 30K miles. Don't wait 100K or whatever the schedule states, or you will pay a lot more than the cost of a coupel oil/filter changes. If the engine overheats, or you tow or haul loads, or drive in hilly areas with a lot of TC slippage, change more frequently. Heat will break down trans oil faster than anything.

If you think you're having trouble with your 4L60, try a new Jeep with a D/C transmission. You'll wish they were still using Hydramatics, like they used to.

[blazes9395]

Originally Posted by 95xjsport

ok, all I would need it have reamed is the valve body? thats the part that kinda looks like a maze right??

Funny way of describing it, but yes, that is the part.