Hello all,

I am ignorant when it comes to understanding torque converters and stall speeds. I picked this mod up from an e-mail. "Add a 4.9 Caddy Torque converter with a stall speed of ~1700 vs. the stock 3800 SC one which is about 2050." The purpose was to increase the 0-60ft timeslip.

What are the pro's and cons for doing this? Any negative affect on fuel consumption, or higher end torque?

And anyone have a good way to explain what "stall speed" is, and how the difference in range affects driving?

Thanks!
Greg

That's a new one for me. Usually you'd want to increase the stall speed to get the engine at a higher RPM quicker. The only advantage I could see is if with the stock 3800 convertor you were burning the tires off, then going to a lower stall might help you hook up.

Any experts here?

RCR is right...higher is better....

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quote Originally posted by Seanpaul: RCR is right...higher is better....

That's what I was thinking, and the cause for a lot of my confusion. I thought modified TQ converters were more into the 3000-3800 range.

I am still slightly confused on how the TQ converter works. Does the tranny not engage until it hits the stall speed? For example... If you had one with a stall speed of 3800, it would not go until you reved it past 3800rpm (thus faster take off 0-60ft). And in this case, would it also not downshift properly for highway driving? How would that be affected?

Thanks for your enlightenment.

Greg

I talked to a gentleman at the 20th that had a 3800IISC and a caddy 4.9 4T60-E with the 4.9 converter and he didn't like it. He said it bogged off the line because the RPMs were too low for the supercharger...I believe him.

I am thinking you don't want to use anything less than the stock stall that comes with the 3800 II SC.

A higher stall converter (3800 rpm or so) acts just like any other coverter only it will allow the engine to rev higher before the car really goes. It will still move at lower RPMs but the engine just has to spin a little higher especially when you are going up hills and such. Honestly, why anyone would want a 3000 stall or higher on a 3800 II SC in a Fiero is beyond me. You will be building so much heat in that trans and your 0-60 times will suffer. The person before that mentioned the quicker 0-60 times would be better with a lower stall is somewhat correct. That statement holds true so long as the RPMs aren't so low off the launch that the engine boggs. The rule of thumb is you want to select a stall speed about 400-800 rpm less than the engine's peak torque RPM depending on what you are doing with the car.

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1987 Fiero Coupe 3800 Series II Intercooled Turbo
1987 Trans Am GTA 5.7L Superram 4L60-E
1985 Fiero SE 2.8 (soon to have an L36)

Fiero-related Conversions Performed:
1985 SE 3800 Series 1 SC 4T60-E
1987 Coupe 3800 Series II Turbocharged 4T60-E
1987 SE 3.4 TDC 5-speed
1984 Coupe SBC V8 non-OD to 4T60 OD swap, electric power steering install
1985 SE 3800 Series II Supercharged 4T60-E

http://dtcc.cz28.com

V8dreamer is the one with a 4.9 t/c in his 3800 s/c and he is soooo looking forward to getting it out of there for one that has a higher stall.

You should contact him for the one he is looking for, he has done some homework on it along with Rockcrawl.

Pete

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I suggest you call someone who rebuilds torque converters. Tell them what you have and what you are doing with it. They can build the perfect converter for your application. There is a place in Philladelphia called Pat's Converters. They will rebuild a 4T60E converter to whatever specs you want for $125 plus core.

Thanks for your input guys. "+"s for everyone!

Greg

Check with Daaco (sp?) they remanufactur torque converters.
The most exsoensive one I have ever bought from them direct was $40 add another $20 they will make it stall to what RPM you want. Local parts store wanted $169 for a Daaco TC , I drove to their plant and bought it for $41, the extra $1 was because I paid cash Check or money order would have been even $40...

quote Originally posted by jb1: Check with Daaco (sp?) they remanufactur torque converters. The most exsoensive one I have ever bought from them direct was $40 add another $20 they will make it stall to what RPM you want. Local parts store wanted $169 for a Daaco TC , I drove to their plant and bought it for $41, the extra $1 was because I paid cash Check or money order would have been even $40...

Give us a phone # to order direct, and I'll give you a double +.

Thanks,
Greg

They have differant plants across US , I have never ordered usually go pick them up myself (10 min drive)
The phone # to the local plant here is 931-469-7544 , They do require a core.

What about the stall speed from something like a 3.4 dohc or even a quad 4 if they came with 4t60s?

Gene

Hey Greg,
You can "see" your stall speed by holding the the brake, (don't let the car move), and give it the gas. The RPM will only go as high as the "stall speed". The purpose is to get into your best RPM range for HP... like slipping the clutch. You will give up some MPG when going to a higher stall converter.
Kevin

The "stall speed" is when full power is applied to the trans. There is a percentage of slippage as you approach stall speed.
The higher the stall speed the less spin you'll get on the tires off the line. If you want to launch near the stall speed, Just hold the brake and give it gas. When the "brake stall speed" is reached, the RPM's will stop rising. There is a difference between the "stall speed" and the "brake stall speed". I think it's 400rpm but I'm not sure.

The stall speed is a percentage of the torque. So if you have a converter from a 2.5L that has a 2000rpm stall, Putting a V-8 raises the stall speed.

I got my converter from Pro-Torque. It is a standard GM size (9") so it fits the TH125 and the 4-spd auto transmissions. It is a street/strip heavy duty converter. They adjusted my stall speed to match the engine.
www.protorque.com

Very good people to deal with. I just told then my engine size and spec's and they dialed in the converter. Cost is $395.00

Here is the original Email I got when I inquired about their converters:

Thank you for inquiring into. Our price for this torque converter, part #PTC-FZBBHD, is $395.00 + shipping. It is a heavy duty converter built to withstand the abuse of a street/strip application. We have already done some of these in many performance FWD GM applications.

We always like to match the product with the application. Also keep in mind that stall speed is in direct relation to the amount of input torque. It is our recommendation to speak to one of our techs in order to determine your needs. If you have any questions or comments please feel free to e-mail or call at 631.218.8700. I would be happy to answer any questions that you may have.

Thank you
Joe Rivera
PROTORQUE
1440 Church St.
Bohemia, NY
631.218.8700

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Happiness isn't around the corner...
Happiness IS the corner.

[This message has been edited by Oreif (edited 08-13-2003).]

Help,
Sorry to interupt this thread, but I'm in real need of some technical advice. I'm attempting to do an ACE 3800 SC Conversion using a 98 3800 SC and the orginal 4T65E transmission, the axles are really putting a halt to the whole project. I have gotten the right side set up, but the left is confusing the crap out of me. I'm supposed to be able to use a left side Getrag 5 speed manual axle with the donor car inner CV Joint, well it all goes together alright until I try to put the suspension back on and the axle is about an inch and a half to long. Am I doing something wrong or do I have the wrong combination of parts?

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Ron, aka: Blackrams@att.net
88 Formula, Stock, auto, 3800 SC swap in process
88 Formula, 4.9, auto
88 Formula, Stock, 5 Spd, T Top, My Favorite!
88 Formula, 5 Spd, Stock

quote Originally posted by blackrams: Help, Sorry to interupt this thread, but I'm in real need of some technical advice. I'm attempting to do an ACE 3800 SC Conversion using a 98 3800 SC and the orginal 4T65E transmission, the axles are really putting a halt to the whole project. I have gotten the right side set up, but the left is confusing the crap out of me. I'm supposed to be able to use a left side Getrag 5 speed manual axle with the donor car inner CV Joint, well it all goes together alright until I try to put the suspension back on and the axle is about an inch and a half to long. Am I doing something wrong or do I have the wrong combination of parts?

The guy who is installing mine reuses the GTP axels by having them machined down, and everything hooks up prefect. It costs him $150 for the machining. If you have the GTP axels and want to ship them for machining, I can get you the info.

I've heard of other alternatives that you can use, but I don't remember. It might be easier to find that other stock axel from the forgotten vehicle.

Hope that helps some,
Greg

Unfortunately the '98 Buick Riviera is using some off-the-wall tranny ouptut, at least on the right side. As far as I could find out, only a '98 or '99 Riviera or Park Ave axle will fit on the right side. I did manage to fit an '87 Auto V6 left side axle into the Riviera 4T65, and it also fits into the hub/bearing (naturally, it's a Fiero axle...), but I didn't check the length while I was down with the car.. (DOH!!) Anyone have an '87 Auto axle around that they can measure for us poor guys using the Riviera transmission?! Next time I'm going GTP...

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Bob Williams
Multi-colored '87 Mutt, a work in progress! (Got my 3800SC, installation in super-slow-motion progress. Only a Miracle will get me to the 20th in my Fiero now. Or a time machine...)

Greg,
Thanks for the advice, I've got the right side axle set up and hooked up to the suspension, the left side is where I'm having a problem, the stock Fiero left side axle meets up with the 4T65E tranny/axle shaft perfectly, but the damn thing is too long to put the suspension back in place. Haven't given up yet, will keep you posted.
Bob, See the email I sent you, maybe you can get something out of that.

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Ron, aka: Blackrams@att.net
88 Formula, Stock, auto, 3800 SC swap in process
88 Formula, 4.9, auto
88 Formula, Stock, 5 Spd, T Top, My Favorite!
88 Formula, 5 Spd, Stock

Don't know if this will help, since my conversion was a 95 Buick Riviera auto into an 85 4cyl 5spd. My left 5spd axel worked on the left. The left Riviera axle worked on the right. The assembled, COMPRESSED overall lengths are... Right-23 1/4" and the Left- 20 1/4". the dissassembled axels are...Right- 15 1/2" and Left- 14 1/2". Spacing between the boots should be... Right- 3 1/2" and Left- 2 1/2". I can't explain why there is a 3" difference in Compressed length but only 1" difference in the axles. Hope it helps.
Kevin