What make stock converter so bad?

[Deathrod]

Besides not having lock up is it poor fluid coupling or the clutches slippin and slidin, or something else? What makes an aftermarket one have better efficiency? I've always heard how horrible the stockers are but not exactly why.

[Tacoclaw]

The Cummins engine was made for a medium duty application. When they decided to toss it in a "light" duty pickup, they found that the rest of the truck's drivetrain was completely overwhelmed by it. Just look at how de-tuned these engines come, with about 2 hours and some hand tools, you can add another 100hp to it easily.

De-tuning the engine wasn't enough, so they had to find another way to lessen the strain the drivetrain took. The easiest way was to just let the torque converter eat it up, since it was all fluid, the only damage that could be done was heat buildup. It's made to stall above the engine's torque peak so it not only ditches some power through heat, but it also keeps the engine out of it's ideal powerband.

It was just the best/cheapest way for Chrysler to keep these trucks out of their shops with nonstop warranty claims on twisted driveshafts, shucked rearends, and slipping transmissions.

[Diesel]

The Cummins engine was made for a medium duty application. When they decided to toss it in a "light" duty pickup, they found that the rest of the truck's drivetrain was completely overwhelmed by it. Just look at how de-tuned these engines come, with about 2 hours and some hand tools, you can add another 100hp to it easily.

De-tuning the engine wasn't enough, so they had to find another way to lessen the strain the drivetrain took. The easiest way was to just let the torque converter eat it up, since it was all fluid, the only damage that could be done was heat buildup. It's made to stall above the engine's torque peak so it not only ditches some power through heat, but it also keeps the engine out of it's ideal powerband.

It was just the best/cheapest way for Chrysler to keep these trucks out of their shops with nonstop warranty claims on twisted driveshafts, shucked rearends, and slipping transmissions.

Please cite to source.

[oldestof11]

For some reason, mysteryman (or something like that) on TDR has the whole story as he was a Chrysler employee...

[cmann250]

Just to expand on Taco's info, the 6BT was industrial before is was in a pick-up. It came to being out of a Case and Cummins joint deal. I think you got the 727 or 518 in any 3/4 or 1 ton Dodge pickup of the era, gas or diesel, no matter what. The industrial HP rating of a VE 6BT was like 90. The low HP rating is because Industrial and ag stuff has to last forever. FWIW non-IC'd trucks have dynoed at 170 rwhp bone stock.

Cummins- overbuilt and under rated

[oldestof11]

Just to expand on Taco's info, the 6BT was industrial before is was in a pick-up. It came to being out of a Case and Cummins joint deal. I think you got the 727 or 518 in any 3/4 or 1 ton Dodge pickup of the era, gas or diesel, no matter what. The industrial HP rating of a VE 6BT was like 90. The low HP rating is because Industrial and ag stuff has to last forever. FWIW non-IC'd trucks have dynoed at 170 rwhp bone stock.

Cummins- overbuilt and under rated

A guy I know down here has 2 Cummins, 1 89 and 1 92. Owned the 89 since it first came out. Swears up and down to have proof Chrysler denied his warranty because his 89 made close to 200hp at the rear wheels. They found out when they dyno'd up in Rockford to find out why they couldn't keep a trans in his truck for more than 6 months at a time.

If it helps the story, he has really clean trucks.

[Diesel]

We need a citation to a source on this one. Or better yet if the source has been made electronic we need a copy. If I had to just guess I would have said a stock converter is just the way it is so it can get a huge load moving and keep it moving. Plus the od is so deep at .6 that a little slip on the highway can't hurt.

[The_Head]

Weren't the 727 convertors a little bit tighter than their 518 counterparts? I thought I had read that somewhere.

[cmann250]

A guy I know down here has 2 Cummins, 1 89 and 1 92. Owned the 89 since it first came out. Swears up and down to have proof Chrysler denied his warranty because his 89 made close to 200hp at the rear wheels. They found out when they dyno'd up in Rockford to find out why they couldn't keep a trans in his truck for more than 6 months at a time.

If it helps the story, he has really clean trucks.

I remember you telling me that at SOP... Interesting

[oldestof11]

From DTR one of the few times he actually posted there:

It really pains me to read some of these posts.....I recall all the pain we went to while developing the first cummins trucks . Getting them to stay together was the biggest challenge ! Staying with in our budget was the second.

If everyone left them stock they would last for years and years and get a lot of work done during that time. But if everyone out there keeps doing all the modifications I read about on the various boards on the net. Soon there will not be any of the first gen trucks left.

I have always been amazed by some of the guys out there that will try to argue with me about how to design and or set up these trucks! Many of the worst I find have never even graduated from high school much less had any training in automotive engineering!

I am not sure who was the bigger fool in that tale...Dad for setting up the truck the way it was or the son for blowing it up....If either one of the 2 would have left the the truck alone. Neither of them would have ended up with a problem in the end....

[PToombs]

He wasn't like that before he got sick. Now he rants and raves like that everytime he sees a post about more power. He's posted on here like that.

[Deathrod]

Just to expand on Taco's info, the 6BT was industrial before is was in a pick-up. It came to being out of a Case and Cummins joint deal. I think you got the 727 or 518 in any 3/4 or 1 ton Dodge pickup of the era, gas or diesel, no matter what. The industrial HP rating of a VE 6BT was like 90. The low HP rating is because Industrial and ag stuff has to last forever. FWIW non-IC'd trucks have dynoed at 170 rwhp bone stock.

Cummins- overbuilt and under rated

I think I heard that jack roush (of all people) was the guy who pulled the motor out of a case tractor and put it into the trucks....I don't have a clue of how he was involved with Chrysler.

But back to the original question.....what does goerend do to make them "tighter?"

[bmoeller]

Just to expand on Taco's info, the 6BT was industrial before is was in a pick-up. It came to being out of a Case and Cummins joint deal. I think you got the 727 or 518 in any 3/4 or 1 ton Dodge pickup of the era, gas or diesel, no matter what. The industrial HP rating of a VE 6BT was like 90. The low HP rating is because Industrial and ag stuff has to last forever. FWIW non-IC'd trucks have dynoed at 170 rwhp bone stock.

Cummins- overbuilt and under rated

I think I heard that jack roush (of all people) was the guy who pulled the motor out of a case tractor and put it into the trucks....I don't have a clue of how he was involved with Chrysler.

But back to the original question.....what does goerend do to make them "tighter?"

Probably changing the stall speed on the t/c and increasing the line pressure to keep things from slipping. Aside from changing some bad hard parts (sun gear in the O/D unit and burnt clutch packs) in my '97, that's what he did.

[bmoeller]

The Cummins engine was made for a medium duty application. When they decided to toss it in a "light" duty pickup, they found that the rest of the truck's drivetrain was completely overwhelmed by it. Just look at how de-tuned these engines come, with about 2 hours and some hand tools, you can add another 100hp to it easily.

De-tuning the engine wasn't enough, so they had to find another way to lessen the strain the drivetrain took. The easiest way was to just let the torque converter eat it up, since it was all fluid, the only damage that could be done was heat buildup. It's made to stall above the engine's torque peak so it not only ditches some power through heat, but it also keeps the engine out of it's ideal powerband.

It was just the best/cheapest way for Chrysler to keep these trucks out of their shops with nonstop warranty claims on twisted driveshafts, shucked rearends, and slipping transmissions.

Please cite to source.

You don't need a citation. This isn't Wikipedia. It is a known FACT to anyone who has been around them long enough (11yrs in my case). A '97, 99, 92 and now a '93.

Any stock Chrysler t/c behind a Cummins is horribly inefficient. The stock trans and t/c in my '97 was so bad, I literally picked up 10# of boost by just swapping in the Goerend-built trans. Had Dave's crew install it. The t/c in the 1st gen trucks also do NOT have a lock up clutch in the convertor. No way to keep the t/c at 1:1 with the engine like a clutch with a manual transmission would.

[Tacoclaw]

Yeah, I've got no actual source for my post. It's just a gathering of all the post, conversations, and articles I've read over the years. Most of those were opinions as well, so take it as you will, but I don't see a flaw in the logic of it.