Rear End Failure..

[chrisman]

has anyone ever heard of the differential failing?.. rdm was driving around, and i think the rear end broke.. i havnt been able to check it yet but id like to see if anyone has even heard of any failures.. i had always thought the rear end can take alot of abuse..
at least having the car at the shop will allow me to get the extra injectors on..

 

[Zuffen]

What donor car is RDM driving?

The smaller the car the faster the diff dies!

 

[Lextreme II]

My Dif is still ok, but it does leak very little from the read seal. Need to fix that. Crhis, tell me the simple of your dif. When my dif break, then i know its the dif.

 

[chrisman]

zuffen, it was the sc400-1992.. its an open dif.. i think its a 3.7 or something..

i havnt been able to look at it yet--im kinda busy at the shop, so i dont know exactly what is wrong..but rdm he was driving normally, and he heard a small boom.. then he had no power to the rear wheels.. i was able to jack the car up and take a quick look fopr broken parts.. nothing looks broken.and i turned one wheel-- the axle turns but thats where the it ends.. the other wheel isnt turning and niether is the driveshaft..
so it seems to be an internal diff problem.. he has a supra diff at the shop, and i will end up installing it.. but i hope he doesnt have any hard parts that are broken..

 

[Zuffen]

When you rotated the wheel did the half shaft turn?

If the half shaft is turning it may have broken an output shaft in the diff. The only other options are a snaped pinion shaft (I would expect the prop shaft to be flopping around with that problem) or it's blown a hemisphere.

Knowing what the LS diff can take I'm surprised it died.

 

[chrisman]

im surprised to.. i almost have it out.. il have it out tomorow.. and il take some pics.. i dont know what its called.. i call it the axle stub.. but the pas side broke in the diff.. the bearing is still holding it in, but when i rotate it by hand , i feel a wooble..

anyway, il post pics..

 

[chrisman]

well heres some more news and some pics on the rear..from what it looks like, the pin that holds the spider gear snapped.. that was the boom that rdm heard.. now when i was taking it apart, i noticed the pinoin would turn but would lock--this is bad.. i didnt think to look before i removed it, but im afraid when the diff failed, it locked the pinion by wedging a spider gear in the assembly.. this may have done some damage to the trans..

this kinda bums me out.. i think -not sure- that rdm may have also broken some hard parts in the trans..
in any case, i will get the diff back together as soon as i can.. id like to find a set, ring and pinion, out of a na supra if possible.. ii have the torsen diff at the shop, but the gearset in the diff does not look that great.. maybe we can get 4.0 and higher set..
i cant work on the car for about a week,, i need to worry about some other stuff i got goin at the shop.. i will try and check and see how the trans is, but i will probably wait till the diff is back in..
i also need to install the 8 extra fuel injector setup im installing.. by the way, it does fit under the hood..thats great because it looks to nice not to put it on.. well be going to the track 2 weeks from now.. and id like to get some descent sc400 times.. give the sc300 guys something new to worry about.. getting beat by a V8 sc..ha,,,..

 

[chrisman]

heres the pics-this is what i saw when i opened it up.. you can see the bunch of parts in the bottom of the diff..

 

[chrisman]

this is the piece that wedged itself.. i had to remove the side bearing so i could rotate it around to the back..
one more thing.. the guy in the pics is not me--its a freind of mine and rdm.. his name is tom.. hes always bragging on how great his mustang race car is, but i think he likes working on the lexus more than i do.. his always the first guy helping out if rdms car is in the shop..ha, ha,.....i know he'll be there on race day in a couple of weeks--waiting for rdm to break something so he can help out again...its nice to have friends who dont mind getting dirty..

 

[1jza21]

So whats the actually gear ratio on that? Its a 92 SC400 right? Is it a A02A code and what is the teeth count and actual ratio?

Cary
I have one for sale but am In the US so shipping would kill.

 

[chrisman]

its a 3.91 ratio.. 47 teeth on the ring,,12 on the pinion..i dont know if its common, im gonna search..il check the code tomorow..

im also in the us, and may be interested in yours..--depends on the price i guess.. pm me with details if you can..i can arrange shipping, but you would still need to box it.. i would appreciate it..
and yes it is a 92 sc400

 

[1jza21]

They get 300.00 for them here locally hows 200.00 plus shipping sound? Probably 40-50.00 to ship I would guess.
Cary

 

[GSMnow]

The only time I have seen the cross pin break like that was on an open diff when the owner liked to do big smokey one wheel burn outs. When only one wheel spins, the little spider gears spin very fast and with alot of force against the pin. There is no real bearing in there, just steel on steel with some gear oil, but the high speed spinning does not let much heavy gear oil get back in. The result is the spider gear grinding through the pin. When I saw this before, the car would clunk a little when going from forward to reverse. It was an auto trans so it would go THUNK when you moved the shifter. In hind sight we know it was caused by the pin being half the size of the holes in the gears. The quote to open it up was too high so he kept driving it. A few days later he was towed back in.

I run an 85 Supra F303 diff (7.5 inch 3.727 ratio 2 pinion limited slip) in my Celica. After a full season of autocross racing, my diff would clunk a little. It turned out to be the clutch plates wearing and allowing too much clearance. It seems I was lifting the inside rear tire a bit and the diff would work very hard to keep from spinning the crap out of the loaded tire. Well I figured I could do one more event on it. I was wrong. The floating cross pin that holds the spiders in the LSD diff was actually slamming into the carrier. It let go and destroyed the rear end. Hunks of iron went through the gears and into the bearings. No damage to my manual trans though. When it tried to lock the tires I just skidded a bit and hit the clutch fast. It made a crunch and started rolling again. I had to get a whole diff and gear set to fix it. All new bearings as well. If I just stopped when I heard the clunking. Since then I re-shim the LSD every season and check it if I hear any clunks it gets opened up. Since I re-did my suspension though, the inside rear tire stays on the ground and the clutches didn't need a big change in shims to keep it on spec.

Gary M.

 

[1jza21]

Gary nailed it for you. I Drag race my Celica and have found the same thing. The other thing it will do is the spider gear will grab the gear pin and spin it shearing the hold roll pin and the damage ensues shortly there after this was my tipical problem. I went so far as to weld the spider pins in to give me some more time if it did shear the pin at least the spider pin didnt walk around on me. I would not do this its just what I did to buy more time knowing i was going to break the thing eventually anyway.

Cary
Ps hey Gary! Cary from way back on one of those old Celica forums back then.

 

[chrisman]

yea, rdm does like doing smokey burnouts--even before the turbos.. i bet he wont do them anymore.. we have the TORSEN unit that is going in, but all of the bearings are shot as well as the ring and pinion.. thats why id like to get a whole diff..

i have been trying to get some info, but its hard to find.. there are many places i can get ring and pinions,higher ratios, for toyota rear ends--but it seems like they are only for trucks..but this is not clear.. do you guys know what ring and pinions are interchangeable between models?-if any?

also how does quick is the drag celica?

 

[1jza21]

Not sure just yet for this engine combo. Its a 1JZGTE with a single turbo pushing around 550hp before the 100hp shot of Nitrous. It goes through a R154 tranny to a Narrowed 8in Toyota 2WD rearend. And the car weighs in around 2300lbs right now. Oh and its a 1972 Celica ST just in primer at the moment I will start Tubbing it as soon as its running. Should easy be in the 10s maybe better. The Pinions on the SC rears are longer as I recall (dont quote me there)so I dont think the Truck stuff will work I might be able to get an idea tomorrow night when I go to the shop I can take some rough guesses. Gary has been playing with the IRS stuff way more than me he might have an idea as well.

Cary

 

[chrisman]

the celica sound cool.. 2300 lbs is good.. im in the middle of a drag car myself.. its an 87 corolla- 1uz tt.. its in the begining stages, and i havnt had to much time to wrk onit..but should have it out in about 3 months..no tubs though.. itl be street legal--kinda plain jane..

 

[1jza21]

Mine will be steet legal as well. I have 325-50-15 Drag radials on 12in wide Centerline Prostock wheels. Its a 72 so no smog here in California. Yours sounds cool as well good luck with it. I can never seem to find time to work on mine lately.

Cary

Here is the car the new tires are behind it in this picture. The fronts are on.

 

[chrisman]

those tires look huge.. it should be awesome when its done.. but are cars every really done? theres always something to try/do/finish..

your always trying to fix the weakest links..

 

[1jza21]

True it never really ends!
Cary