"Beefy" Transfercase?

[just_passed_you]

91 AWD

The input shafts, splines.... all of it... thrashed/worn.
I'm working with worn, rounded splines.
Output shaft on the tranny as well.

Shep's stage 3 tranny seems to cover all
of the bases, however I'm looking for Dr. Transfercase.

Any ideas?
Thanks guys.

 

[Ludachris]

The only place I know of that will do a stronger-than-stock transfer case is Driveshaftshop. I believe they had Shep help out with the development.

 

[pneumo]

The stock transfer case is strong enough to handle around 500HP, so unless you plan on making more than that I'd suggest simply getting your Tcase rebuilt with stock parts.
At nearly stock power levels the Tcase will wear out after ten to fifteen years because the splines that join the tranny output shaft to the Tcase input shaft is not constantly lubricated. A newly rebuilt Tcase should be good for another ten years of use.

 

[awdtalontsi1992]

I agree. The driveshaftshop transfer case upgrade is over $1000. Too much in my opinion. I would just get a stock rebuild and maybe a upgraded center differential while your at it.

 

[LA97GST]

Agreed just get a rebuilt one with upgraded center diff. and you should no problems for many years.

 

[NewTurboTuner]

But what about people who want more than 500hp?
How much better is the Driveshaft Shop's T-Case going to be?
Or how many stock T-case's will you go through, if you don't get a beef'd-up T-case w/ 500hp+? ....Maybe its worth the money?

I'm going to have to look into a beefy T-case too.
I just got my new S-4 Trans from Shep a few days ago, and my ultimate goal is to have 500awhp on pump gas .....AND!!..... it has to be a reliable. (yeah I know its a far fetched goal, but that's what I'm shooting for.)

....500hp at the wheels in a AWD, is probably 550-570hp @ the motor ....Do you guys think a stronger Transfer case is needed for that kinda power?

I'm the kinda person that wants it done right the 1st time. I dont wanna waste my time and money building 2-3 T-case's in a year... or in two years for that matter. I'd just rather pay $1000 and have it done right the 1st time.

But I'm still new to these cars. What do you guys think?
At what HP level... is a beef'd-up T-Case is necessary to have reliability.

Thanks!!!
~SB

 

[1stGenRocks]

it depends a lot on how you drive it. Obivously launching it hard will put more stress on it then daily driving or slipping the clutch a bit more. It also depends on how heavy your car will be the heavier the car the more stress on the drivetrain. Slicks or street tires?

Basicly the harder it hooks the more s***s going to break.

 

[GRNDSM]

First of all, hp figures are irrelevant when you are talking about drivetrain, which only cares about torque. So please stop using 500hp figure .

I set my car up to make 600+ hp but at under 400lbs*ft of torque. I had ZERO drivetrian failures!

Now, lets look at why your transfer case INPUT splines stripped. 99% of the time this happens because ether the shaft or the female splines were rusty. Rust removes vital material, thus making components much weaker.

I would simply replace the output shaft and transfer case with rust free (or as close to it as you can find) parts and that should solve THIS problem. Of course, you will then find the "next" weak link, which tends to be transfer-case OUTPUT shaft. But that is a different problem.

 

[topstreet]

But what about people who want more than 500hp?
How much better is the Driveshaft Shop's T-Case going to be?

Personally... I have the DSS upgraded t-case and I have to say that it is ALOT bigger of an output shaft. This allows you to run a much larger Yoke and U-joints. In addition to the new driveshaft. There are many things that become much stronger during this upgrade.

That being said: There were people in the 8's on the stock t-case before the upgraded one existed. Every singe person that I have talked to that has broken the stock t-case, has told me that it is because of wheel hop. In your case the situation is different though. You are not breaking gears, you stripped splines. Therefore, the DSS upgrade will do nothing for you.

Take this one as a fluke. The output shaft in the trans is the same spline and diameter as mine is. Currently I am over 600 wheel ft/lbs of torque.

Hope this helps,

Jake

 

[steel_3d]

Does anyone know anything about the strength difference between the pre and post 97 transfer cases? according to Shep the 97+ is stronger.

If it's true, and you're kinda crazy, you could replace the front diff ring gear in your pre-97 tranny with a 97+ ring gear, and run the 97+ t-case They're kinda hard to find, though.

So I'm thinking about rebuilding mine. The bearings are all ####ed from being low on oil, but I'm hoping the gears will do ok. They're a bit shiny Othwerwise, has anyone bought all new bearings and shafts, and how much did it cost? If I can get away with just replacing bearings, I know it'll be pretty cheap. I didn't get to look that closely yet, can the gears be separated from the shafts? That might reduce the cost too.

 

[GRNDSM]

I do not know anything about 97+ being stronger, but I do think that JDM (switchable) transfer case is stronger. I have seen one break, but it broke in a slightly different manner, which suggests that they are stronger... And it came from a car which has just broken 2 US spec (91-96) transfer cases.

 

[4pistons]

99% of the time this happens because ether the shaft or the female splines were rusty

Not true. It seems this way because when those splines fail there is always alot of rust powder found in the X-fer case shaft. But that is the RESULT of the failure not the cause.

Years ago my output shaft failed and I replaced it thinking the same thing. 16 months later it failed again!! As I removed it the second time rusty powder fell everywhere. How the hell could a hardened steel shaft rust away in 16 months? It can't. When I wiped the shaft clean I noticed that the shaft really wasn't rusted, rather it was coated in rusty powder. There were no rust pits on it, no rust on the end of the shaft, no rust in the root of the splines, nothing.

The cause of the spline failure is a worn out center diff. When the side gear shims (thrust washers) fail they allow the output shaft to move excessively. When you're on and off the throttle the shaft moves in and out of the xfer case and slowly files off the splines leaving rusty dust everywhere.

Grab the output shaft and pull on it. If you can move it in and out more than a few thousandths your center diff is worn. No matter how many times you grease those splines it won't cure the problem. Have you noticed there's no factory service specification for greasing those splines? That's because on a properly functioning center diff it isn't required.

Fix your center diff by rebuilding or welding as I did,( http://www.dsmtuners.com/forums/showthread.php?t=173481 ) or you'll just keep stripping them.

Rick - '91 GSX

 

[GRNDSM]

Hey, aren't you the guy who loves to drive (and AUTOX) on a welded center diff 100% of the time? Did this happen on a welded center diff?

 

[4pistons]

I do drive on a welded diff ALL the time. But this happened to occur back when my car was basically stock, about 8 years ago. Stripping the splines the second time is what caused me to weld my center diff. It completely eliminates any lateral movement of the output shaft and unlike rebuilding the stock diff with thrust washers that can fail, it will never, and hasn't, happened again. I've had the xfer case off several times over the years and since then there is NO WEAR or rust on the output shaft splines. And I don't even grease them!

Since I welded the diff I have driven over 90,000 miles, every day, (except this year) drag raced, autocrossed, road tripped, and commuted with no ill effects, breakage or horror stories to tell.

Rick - '91 GSX