How Strong is the 93 FD Rear End?
 

I want to know how much abuse the 93 rear-end can take. I drag race a decent amount and I would appreciate anyones input as to how much tyre the 4.10's can take. Can I jump up to Street ET's or do I need to stay away from that much traction and stay with Drag Radials like the Nitto 555R's?
Thank you to all.

ET Streets are easier on your rear end than Drag Radial type tires like Nitto 555R's.

really?
 

Are you sure about that? Why do you say that?

Once you start making over 300+hp and launching your stock readend FD at above 6k. You will start breaking your read and axels.. Best bet is just invest and save the $$ up and get some 300m axels and a turbo2 rear or kaaz rear with a nice dif brace.. I've seen people break rears on the street and at the track our cars are not ment for drag racing we have to build them to handle the abuse..

Think about it, Drag radial tires don't have much of a side wall so they don't give. ET streets have a nice big side wall which will take alot of the force of a launch.

I wasn't planning on doing monster clutch drops, but....they have more grip than a street drag tire. My F-body was in the 11's and I didn't even put ET's on that for fear of braking it. Ya, it's a wimpy GM rear-end but still.
So the FC Turbo cars had a stronger rear-end......hummmmm (thinking)......what was the ratio? 4.10?

You can try and source a TII lsd from an S5(not sure the exact years) and get a differential brace. Here is a link:

http://www.kgparts.com/brace.htm

Its not the rear end itself, just the LSD unit. S4 FCs used a clutch type LSD, S5 cars used a viscous coupling, and the S6 ( FD ) used a Torsen gear-type LSD. The Torsen has the fastest lockup rate, but doesnt like the sudden torque applied to it from a drag launch. The clutch type is the strongest for this application, but if you do get one from a S4 FC, make sure it is from a Turbo2 car ( N/A cars used a 7" ring gear, while turbos had a 8", like the FD), and you may want to rebuild it, as they do get weaker with age. An aftermarket clutch type such as a KAAZ would be even better, they are stronger and you can adjust the lockup rate.

No, he'd want one from a turbo S4 ( 86-88 ), see my post above.

My bad. I knew it didn't seem write when I typed it. Sorry for the confusion.

Bummer
 

I have a N/A rear end free from a friend of mine. I figured that the Turbo II would be 'beefier'. I'm not interested in making a 1/4 monster. That would be a waste of the RX-7's true roots and purpose. I still have the need to drag so I thought I would check with you guys. You've given me the info I need. I'll wait until I blow the one I have before changing.
By the way, are the Turbo 2 rear ends LSD?

Every Turbo RX-7 is LSD.

Yea, a N/A LSD wont fit because of the size difference, it is physically smaller. All turbo FCs had LSD, see my post above for what years carry which type.

If you need some 300 m chromolys contact me, i have a few in stock.

Thanks
Marc

What I really want is...
 

Actually, I really am interested in some ET Streets for next spring. I'll worry about the rear-end when it breaks. It's stronger than my LS1's and that car ran 11's.
Anybody wanna sell me some?

Hey it's jason down in colorado springs...how much you want for the 300 m chromolys? 719-650-5217

I'm using the FD rear end subframe assembly in a kit car which will have about 400hp and weighs significantly less than a FD, but I'm also going to be using V710s or an equivalent hoosier tire... Do you think I'll be breaking the stock torsen or the stock axles? I will be bracing the diff to the frame.

Yes

which one do you think will be breaking first?