Center Diff Power Limit

[kilurv8]

The stock bottom end on a 7 bolt small rod motor is expected to fail right around 400hp to the wheels on an awd. Does anyone know if there is a general concensus on the stock center diff similar to that. I have a lot of power on a stock center diff and am wondering when I should expect it to explode. THanks in advance.

 

[Jason_Crowe11]

I don't think there is so much a ~power limit~ to the center diff....It's more how you treat/drive the car.

I broke my center diff(still broken)....but I did it launching the car...and no my car isn't stock. I would estimate my car to be in the low to mid 300hp range right now. Using my TMO stutterbox--I launched at 6k and it was fine...spun all 4 tires and was cool as hell! Then at 4500(twice)...it bogged and broke.

Laters
Jason.

 

[larryd]

what are the signs of a broken center diff? is the car not driveable?

 

[Jason_Crowe11]

Well, you can still drive the car...

Personally, I don't want to drive mine with it like it is.
It does drive fine if you drive forward and straight. ....and if you think the center diff is broken...you sure don't want to try and launch the car.

Symptoms on mine:
Backing the car up(especially if turning when backing)....the car will stop(like the brake is on_)...then you continue to push gas..and it will go POP-=horrible sound!...and suddenly rolls again.

Going forward...taking turns sharply==the rear inside tire(maybe outside to?) will bark along(like it drags sometimes)....as if the differential is not working properly.

It makes it kinda scary to think that if I were on the road hauling around a turn at high speed that the center diff could cause the rear end to kinda skip along....possibly throwing the rear of the car out of control. Along with the fact that I don't want to do any further damage...which is possible.

So I just don't drive it right now--till I can fix it.

 

[larryd]

yeah thats definitely not what my car is doing.. basically its locking the tranny on you

 

[Atari007]

Hey Jason... If Im correct, when you blow your center diff, that means no more awd, right? I am having those same basic problems (noises, etc), but it isnt a constant pop noise (ie: pop, pop, pop) as I am turning in reverse... it just does it once (and feels like Im being held back a little).... Im not really sure what to make of it... I jacked the car up off all 4 wheels and ran it in 1st gear, and all 4 wheels still run fine... I was thinking it might be a bad U joint... what do you think?

 

[Jason_Crowe11]

Atari007,
If you are having the symptoms I am(as you say you are)....I'd lead to believe the center diff is your problem to.

A totally blown center diff would I guess not send power to the rear wheels....but a broken center diff will still send powe but acts up like mine. (a welded center diff will have similar feeling to the things mine does as is broken).
Imagine a tooth being broken off or something.....then think of what weird things it could do as the gears try to turn and mesh.

*btw...on mine, I had just had the center driveshaft bearings replaced to help fix the problem...fixed the driveshaft thump, but still have the center diff issue. (and my U joints felt fine).

Laters
Jason.

 

[Awdboost]

What happened to me was I launch my car @ 6500 and spun off the line and then all the sudden got wheel hop. I still continued the race against the Vett but my car didn't really feel right. When I went to turn around my car start to make a clicking CV joint clicking noise. I drove it home fine and everything. I even took it to work the next day. I guess that I the broken gear cause my diff to lock up and my rear tire would spin if I gave it gas. You will know if you break your center diff because it will feel funny. As for how much power you could put on it. I had few mods full exhaust and intake with the stock turbo. So I can tell you that you center diff is weak.. But For the car with the Limited slip rear end. I believe it's harder to break your center diff. It's just a theory thou.

 

[turbo4wd]

I had a similar experience as Awdboost. I lost my center diff while launching at Sears Pt. I wheel hopped and the car went bang bang BANG... I finished my run and when I went to pick up my slip I noticed a click noise. I drove the car home and after getting some gas and getting on the highway I had to gas the car while merging back onto the highway. I felt the car get real squirely... It was the back tires breaking free on the highway. A sure way to know if you lost the diff. Jack up all 4 tires off the ground. Start the car and put it in 1st gear. (Make sure the car is stable and won't fall off the jack stands) All 4 tires should spin. If only the front or only the rears spin, you lost the center. Here is what mine looked like: http://www.turbo4wd.com/BustedCenterDiff.html
-shawn

 

[Jason_Crowe11]

Shawn,

Your center diff looks good compared to mine.

hehe, I opened mine up to have a center diff that sounded like a can full of marbles.

Upon opening it and examining it closer, the spider gear inside exploded into ATLEAST a dozen pieces!....the housing inside was banged to hell....the gears tossed around and around making the whole diff housing look like crap. It also, somehow began to bang the gear nest to the diff--resulting in a large area of metal being shaved off the outside of the diff housing.

*BTW, I killed the diff launching also. I did a few stutterbox launches with my TMO ECU>>the 6K launch worked awesome!!(spun all 4 and took off)......I tried launching twice at 4500>>which resulted in a bog and BREAK. DOH!

I broke the center diff and also wallowed out the center diff bearing(rubber surround)>>so I had driveshaft thump BAD and the diff problem. It sucked.

Laters
Jason.

 

[turbo4wd]

I was pretty fortunate. When mine shattered the gears wedged themselve in the housing. I didn't drive the car hard after it went and when I got home I didn't drive the car at all. (It was really hard to fight the urge to take it out in RWD mode. It was really fun getting loose in the highway!) All I have to say to someone how thinks they busted their center diff. Don't drive the car. It is not worth sending metal chunks though the tranny.
-Shawn

 

[90GSX]

I haven't broken my Center diff yet, but I managed to pull consistent 1.7x 60' times last year with the 16G and a 5K stutterbox launch. I don't think it's a matter of power, but how you drive the car. John Sheppard, for example, said that he keeps the trans in one piece by slipping the clutch off the line a bit. (- From Turbo magazine)

However, last week when I dissasembled the trans to replace a broken shift fork, I noticed that there was some "play" or "slop" in the diff. i dissassembled it and found that, although all the gears were intact, there was some damage to the inside of the housing, the shafts, and the spider gears. Appearantly it had at least one foot in the grave! I ordered a TRE diff locker "spool". (as well as EVO forks to replace the broken one, and new rails, etc...) I'm anxious to get it reassembled and back on the road with the new parts

 

[DSMotorsport]

I just broke the center diff in my shop's car...it was a stock center diff, had a welded viscous coupling too...
on a 5500rpm launch with 4 drag radials...car dead hooked....
snapped a 4 bolt drivers axle....
it also ripped the weld on the viscous coupling and shattered the center diff......it actually broke the cross pin, and the one big side gear.

 

[DSMotorsport]

oh yeah...all that damage was one launch..and car didn't even move...obviously no driving after it broke.