Transmisions

[jdrumstik]

If you don't want all of my rambling move down a couple paragraphs

Im going to be rebuilding a 454 and plugging it into a ElCamino. Im putting my self on a nice budget, since Im going to be doing this over a long time, and I want to do it right. Ive got the next year for the engine, which i will be doing myslef, on a nice budget, above $2000, but its hard to tell.

so I will need a transmision, and I eventually want to dump a supercharger on the 454, I don't know anything about superchargers, but im estimating under 10 ibs of boost.

my estimaiton for the engien is above, 500hp with out the supercharger. and I might be stupid, but if you can nitros charge a supercharged enigine, I'll do that too.

so naturally it will have loads of power, which calls for a more than stock trans.
as long as im replacing something im doing it right.

its got to be

Manual
5 or 6 gears
has to hadle 500+hp

in popular hotraoding this guy had a cuda, with a 408, and a holley 174 super charger making about 550hp, he used a tremc TKOII five speed, thats great, but I might need something stronger and perferably a 6 speed.

eaby had a few ripped out fo corvettes, but I wasn't sure if that was what I was looking for. Any idias? are 6 speeds actually used in the muscle cars world? and surely the stock 4 speed wouldn't work right? any idias are a preciated

[PWMAN]

What year el-camino?
http://www.keislerauto.com/gm/chevelle.html

[MagicRat]

When you get into that kind of power, manuals tend to rip up the rest of the car, (rear ends, exploding clutches etc) Just use a scatter shield.
I don't think any cheaper trans will hold up to well, unless its really been rebuilt well for this kind of use.
The 6 speed from the late model 'Vettes will survive.

Give the Lingenfelter corvette builders a call and see what they use.
But this is big$$$$$$$$$

Doug Nash used to build the 4+3 overdrive 4 spds for the '80's vettes and they are quite strong. Doug Nash also built an aftermarket 5 speed especially for racing and high performance for many years.
Good luck, or save lots of $$$$$$ and use a THM 400.

[PWMAN]

Originally Posted by MagicRat

When you get into that kind of power, manuals tend to rip up the rest of the car, (rear ends, exploding clutches etc) Just use a scatter shield.
I don't think any cheaper trans will hold up to well, unless its really been rebuilt well for this kind of use.
The 6 speed from the late model 'Vettes will survive.

Clutches exploding? If they can make clutches for diesel trucks that handle 1500 ft/lbs of torque I'm sure there are clutches that can handle 800 ft/lbs from a BBC.

That Keisler transmission link I gave says their tranny will withstand 650 HP, I'm sure they give you a clutch to handle that too.
As for the rear end, well it's your own fault if you put 500 HP to a stock 10 bolt. And if it has a 12 bolt, than beef it up with heavy duty axles, green bearings, Richmond gears, C-clip eliminators, ETC.

[jdrumstik]

Im working on the engine right now, a 454, I actually don't have an ElCamino, yet. But soon. So I was just looking around. pricing up, Jegs sells a rebuilt 6 speed thats pulled from a vette, its like $3500, which is expensive, its a double overdrive if I remember right, they sell a 4 speed for just 1500 with the same first four gears, no od, but I estimated that as a daily driver, although with low dialy miles, the 2000 extra would eventually make up for in gas, driving a 454.

[MagicRat]

Originally Posted by PWMAN

Clutches exploding? If they can make clutches for diesel trucks that handle 1500 ft/lbs of torque I'm sure there are clutches that can handle 800 ft/lbs from a BBC.

That Keisler transmission link I gave says their tranny will withstand 650 HP, I'm sure they give you a clutch to handle that too.
As for the rear end, well it's your own fault if you put 500 HP to a stock 10 bolt. And if it has a 12 bolt, than beef it up with heavy duty axles, green bearings, Richmond gears, C-clip eliminators, ETC.

Yes, 800 ft lbs is more than enough to explode a clutch!!
I have owned, driven and worked on heavy trucks and I have driven race cars.
I know first hand the applications for the two are completely different. Your truck is not wound up to 5000 rpm before dumping the clutch at the green.
It is not the constant torque that blows the clutch, its the load imposed from a hard shift or launch that blows a clutch. For a split second, the load far exceeds that of a big truck.
If one is tries that on a heavy truck, the universal joints on the drive shaft will let go long before the clutch will.
Besides, if clutches exploding were not a serious problem, then why do tech inspection at any drap strip require scatter shields or ballistic blankets on every car that meets or exceeds 12 sec trap time (or whatever the spec is for a particular strip)
Personally, I like my feet intact and I would NEVER race a car like this without a scatter shield. One can drive casually on the street without one, but if thats all one wanted to do then whats the point of 600 hp in the first place.

[PWMAN]

Originally Posted by MagicRat

Yes, 800 ft lbs is more than enough to explode a clutch!!

Not if you get the right clutch, sure any stock or medeocre clutch will blow up but not if you get one right for the job. Like I said about the differentials, if you put a stock clutch in a car making 800 ft/lbs well thats your fault.

I see your point about 5000 RPM then dumping the clutch, but still there are a lot of diesel trucks pulling 12,000+ pound trailers making 1500+ foot pounds-what happens every time they shift or for that matter take off the line in 4WD pulling 6 tons, not to mention the truck weighs over 3 tons itself. And if they can do 2000 RPM, dump clutch with 10 tons and 1500 ft/lbs, well you get my point.

[MagicRat]

Originally Posted by PWMAN

Not if you get the right clutch, sure any stock or medeocre clutch will blow up but not if you get one right for the job. Like I said about the differentials, if you put a stock clutch in a car making 800 ft/lbs well thats your fault.

I see your point about 5000 RPM then dumping the clutch, but still there are a lot of diesel trucks pulling 12,000+ pound trailers making 1500+ foot pounds-what happens every time they shift or for that matter take off the line in 4WD pulling 6 tons, not to mention the truck weighs over 3 tons itself. And if they can do 2000 RPM, dump clutch with 10 tons and 1500 ft/lbs, well you get my point.

I agree with you. My first post on the subject was advice to get the right clutch, and that it would be expensive, not to avoid one altogether.
Besides, every good race clutch set up I have ever seen uses a steel bell housing that doubles as a scatter shield. Such an item should be considered essential. Again, the point was to either spend the money to do it properly, or not do it at all.
You are saying the same thing.

As for truck clutches, its not the weigh of the truck that makes the difference, its the kinetic energy stored in the rotating parts.
Kinetic energy increses by a factor of 4 times, as the speed doubles. A crankshaft spinning at 3000 rpm has 4 times the amount of force acting on the clutch than one spinning at 1500 rpm.
Therefore, a BBC at 5 grand is likely to have more energy to deliver to the clutch than a truck engine at 1500 rpm.
Finally, truck clutches do not grab the way an auto engine clutch does.
In my experience, the engagement is a bit 'softer' and thus more gentle on the parts, regardless of how you dump the clutch. This is because, in part, a truck clutch disk is actually quite small (12" dia on my Cummins 855) relative to the size and torque of the engine.

[PWMAN]

Originally Posted by MagicRat

As for truck clutches, its not the weigh of the truck that makes the difference, its the kinetic energy stored in the rotating parts.
Kinetic energy increses by a factor of 4 times, as the speed doubles. A crankshaft spinning at 3000 rpm has 4 times the amount of force acting on the clutch than one spinning at 1500 rpm.
Therefore, a BBC at 5 grand is likely to have more energy to deliver to the clutch than a truck engine at 1500 rpm.
Finally, truck clutches do not grab the way an auto engine clutch does.
In my experience, the engagement is a bit 'softer' and thus more gentle on the parts, regardless of how you dump the clutch. This is because, in part, a truck clutch disk is actually quite small (12" dia on my Cummins 855) relative to the size and torque of the engine.

I see what you mean about the RPM thing, but I find it hard to believe that weight doesn't make a difference in the stress of the clutch.

My brother has an 02' ram cummins, it has 13'' clutch. I am on some cummins forums and I always here the stock clutches going out on these things when they add mods. My brother(diesel mechanic)says it's because the idiots that drive them always dump the clutch revving it up. You are supposed to let the clutch fully engage giving no throttle, then floor it. His clutch has held fine, and he has a few mods. He took his truck to work on the dyno, 690 ft lbs to the rear wheels.

[MagicRat]

Thats the way I was taught to drive a big diesel, too.
No throttle, ever, while releasing a clutch from a standstill.
Lots of inexperienced drivers give it some throttle (maybe they are used to cars), and, as you say, its incorrect, and hazardous.
I always maintain if you need to give it some throttle, the starting gear is too high, and you need to use the deep reduction set.
As far as the weight of a vehicle making a difference, I think if one is going to abuse a clutch by winding up the revs and dumping the clutch, the stress is hugh, wether the vehile is 2000 lbs or 20,000 lbs.
But thats just my opinion.
I have heard those Dodge cummins can produce far more power than stock ,and that they are deliberatly detuned, (especially the ones in the '90's) so the trans, especially auto trans will last longer.

[PWMAN]

Originally Posted by MagicRat

Thats the way I was taught to drive a big diesel, too.
No throttle, ever, while releasing a clutch from a standstill.
Lots of inexperienced drivers give it some throttle (maybe they are used to cars), and, as you say, its incorrect, and hazardous.
I always maintain if you need to give it some throttle, the starting gear is too high, and you need to use the deep reduction set.
As far as the weight of a vehicle making a difference, I think if one is going to abuse a clutch by winding up the revs and dumping the clutch, the stress is hugh, wether the vehile is 2000 lbs or 20,000 lbs.
But thats just my opinion.
I have heard those Dodge cummins can produce far more power than stock ,and that they are deliberatly detuned, (especially the ones in the '90's) so the trans, especially auto trans will last longer.

Yup.

Yes they are detuned, they are supposed to have 375 HP and 660 ft/lbs. But they can still be turned up plenty more as the internals are WAY more stronger than any other diesel in a pickup.

[jdrumstik]

so I think I've pretty much got the trans figured out, but its all expensive.

I if was running these gears

1st: 3.28
2nd: 2.14
3rd: 1.57
4th: 1.24
5th: 1.00
6th OD: .76

out of a vette, say through 500 base hp, and lets set the torque equal, what would be a good ratio for a 12 bolt? Whith gas milage in mind, but at the same time street preformance.

And would it be a good idea to buy some 12 bolt out of a heavy duty GM truck at the junkyard, rebuild it, and then have some one smart set the gears so it doesn't seeze?

[PWMAN]

If you are going to rip out the rear end, don't stick a 12 bolt back in. Go with a custom made Ford 9'', or even a DANA 60. Pack it with 4:10 or 4.56 gears.
If the car comes with a 12 bolt, then just beef it up with better axles, richmond gears, C-clip eliminators, 4:10 or 4:56 gears, ETC.

A truck axle will need to be narrowed for a car, it's not worth the effort to do to a 12 bolt. Now if you grab a DANA 60 out of a 3/4 ton truck, that will be worth your time and money. But there are a lot of places that build Ford 9'' rear ends ready to bolt up to any car.

[MagicRat]

Most people seem to run the 9 inch Ford when they can afford it.
The 9 inch seems to be lighter, too, than a 12 bolt, at least when I have had to drag them around the shop. The housing is the difference, its welded stampings, not cast steel.

[PWMAN]

Originally Posted by MagicRat

when they can afford it.

Ahh, the key phrase! LOL
Thats why I didn't get one for my A-body mopar.$$$ Would have been over $2K.