So i ran it at the track crappy 60' but good mph went 11.9 @126 with a 2.1 60'. So i lowered the psi in the tires for the second run then boom rear end broke (well the housing of the rear broke) i was wondering is this common or rare and should i just go with another fd rear or is there something stronger i could go with. I will post pics of the rear later from the computer when i get off work.

 

It is a common failure with the fd rear end! The casting is brittle and the torsen type gears are weak. It is a great diff for racing and other things...... but for drag strip launches its a no no.

Unless you do a few things to protect it. They have pumpkin cradles/brace that helps with holding the case together. Plus of course you know about the many LSD units offered to replace the torsen. Then wheel hop is most likely the killer of your diff. A good samberg diff brace would keep it from slapping around while u doing a hard launch. Stock its setups have been pushing 9's and better in the 1/4 mile, so its proven it can be done.

If all else fails do a cobra its swap. All the info needed is in the pages of this forum. And also wanted to say great pass. I'm still trying to get out the 12's. My best 12.5@125, 2.4 60ft.

 

Thanks yea it has a kazz i went 11.8 @119 on 12 psi with a 1.8. Yea i heard of people doing the cobra swap im going to look into it. Would you no about how much that swap is and does it invole alot of fab or is it more of a bolt in thing

 

Did you drop the clutch with no slip? What tires? Preload the drivetrain so there isn't a big shock to it?

 

Get a PFS diff cradel you wont break the diff casting again, then you will jaut snap axles/ inner cups, this problem is solved with the driveshaft shop stage 5 axle kit.

Cobra irs not needed unless you plan on canging trannies and need infinite gear avialablity.

 

Yea drop the clutch around 6500 i have worn set of nittos. Im making around 470rwhp i was really surprised to see it look like it did i figured the lsd and or pinion gear went but just a big gap in the housing. Im going to look into the cradel and the axels thanks guys for the input.

 

perfect combo for a broken FD diff. preloading it or not sidestepping will help dramatically.

 

How can i preload a stick car??????

 

 

line lock

 

Pretty sure you'll be good with a diff brace and a new housing. What's you setup like power wise?

As mentioned before, a torsen/brace/axle kit can get you int he 9's

 

Went to driveshaft shop website and there is nothing there that says stage 5, so r u talking about the rear axle bar upgrade that cost almost 600 or the Pro level axle/hub kit that that cost 2000?

 

Pro-Level unit

 

Well idk if i can swing 2g for the axle. But would it be worth uying the upgraded bar or a waste. Power wise im making about 470 on 16psi i need bigger injectors for more boost also running water meth

 

Also you think i destroyed the lsd and or the pinion i was thinking the the teeth may be ate up

 

Jesus Christ I built a ford 9 inch for my starlet with 2 grand

 

I just let the clutch slip a little to get the car staged at the 2nd yellow stage light, to get rid of any slack in the drivetrain, works good for me. Now that you have learned not to drop the clutch, you could rebuild a fd rear end with a FC TII diff and you will be okay if you slip the clutch a little on the launch, or get a tilton flow control valve for best results, and some ET Streets and you shouldn't break anything as long as it isn't wheel hopping too (solid diff mounts too). And you can get fairly decent 60 ft times with tire spin which will help prevent breakage.

 

a line lock and a little bit of clutch grab = preloaded diff. 6.5k, stickies and sidestepping = exploding diff, even a 9" will have a tough time with that criteria.

 

Yea im going with the et streets. Yea the only reason i was dropping the clutch at that rpm was because thats what i been reading to do with these cars i thought it was weird but i guess thats if your not making big hp numbers. So the tll diff will bolt rite in??????

 

T2 unit is a bolt in affair. I haven't read everything in this thread but I hope your Kaaz is still in working order...

 

Yea me too i havent had time to get in there and take the rear out

 

bolt in as far as the third member assembly. your case is cracked, so no it won't be a direct bolt in affair as you need a new FD differential case as well.

as far as i remember you also need the TII axles as well.

 

Figured i would need the axles to. Where can i find a fd diff been looking all over

 

You don't need the axles, I installed a TII diff unit with my stock axles and housing. You just need alot of shims to get it shimmed right cause you can't just use the old shims, so the install is not so easy, but that's the same pretty much anytime you rebuild it so no difference for you now. Check ebay or japan2la on here.

 

Ok cool thanks