Hey friends,

Over this past weekend I had made 9 1/4 mile passes on the weekend in my 83 Rb20det GSL RX-7 with no traction on street tires until the 10th run when I decided to skip the water with a proper burnout and broke an axle.

Best run was a 13.68 @ 103.5mph with wheel spin all through first and a 2.1 0-60.

Here's a link to my build thread and runs at the strip.


https://www.rx7club.com/build-thread...1059806/page2/


Now having a broken axle I'm in a dilemma. I have always known this would happen but did not know when and at such point I would source a Ford 8.8 with an lsd.

But having been reading some things since the departure of my axle I am now understanding that there are three main upgrades and please correct me if I'm wrong:

Ford 8.8 with Trac-lok

Toyota 8" from v6 and I4 turbo models with the Mk3 supra diff?

and upgrading the factory GSL disc brake/ lsd setup to moser axles and a torsen diff?


Now I am leaning towards the toyota/supra diff setup and am wondering if this is the right way to go. I am unsure if I need a housing with a disc brake setup or not, or what the hubs are like.

I'm trying to build a reliable car that can handle weekends at the track or strip.

I'm really trying to gather up an equation for cost x reliability x performance but would love to hear from those who have seen or done these swaps.

BT

 

the 2nd gen Toy truck axle I used is actually shorter width wise inside drum to drum, its the width of the drum that makes it overall wider, it has v6 diff with stock 4.56 gears, the project is not done so I don't have performance info.

why are you looking to use a supra diff, I have been running mini toy diffs in my crawlers for years with out issues. unless the whole supra axle is what you are using to get the disk brakes..

 

Wow, I am running similar times and haven't broken an axle yet.

My plan is a full floating 9" (because I like overkill) with gundrilled axles and an aluminum centersection. Time is money, and I have time before the swap is mandatory, so I am low-level watching for deals on used pumpkins/rearends. Although, a NEW housing/hubs/axles/rotor deal is remarkably cheap, so I may just go that route.

 

I've not much info on the toyota setup yet, only learned of it today actually... I was under the assumption the LSD 8" rear ends where hard to find. There is no way in hell I'll put an open or spool diff in it lol. I am seeing some disc brake conversion kits but may cross that path when I come too it. Just worried about the diff/ axle setup now.


BT

 

What do you mean by new? and remarkably cheap? lol

BT

 

Probably $1500 for everything. The axle set will be $900 or so of that, then I need to buy a pumpkin, gears, and diff. Ideally I'd make the Mazda calipers fit so I can keep the cable brake. I'd want to do it at the same time I do the T5 so that the driveshaft expense is shared.

No more bending housings, no more hunting down increasingly hard to find two-year-only parts, the pinion sits lower so I can get the car lower to the ground, and as a fringe benefit, I'd be able to easily flat tow it, just pull the axles out.

 

Hmm, I'm thinking I should almost start a FB rx7 Rear end options master thread. I'm gonna have to do some research. Would love to find something as a stock replacement from another vehicle with disc brakes and lsd with 400hp capabilities.

BT

 

what all do you have done to your car to get into the 13S ,I'm trying to get into the 13S or hi to mid 12s,currently I am running a bridgeported 12a with a Holley intake and carb and the other usual bolt onsjust wondering what else I need to do to get there

 

I put a Toyota 8" in my FB, and I like it . . . a lot. My car's making reasonable power, so I made the upgrade before I broke my original rear end. I also went with the Supra Torsen. I'm able to put down power very smoothly out of the corners on road courses. I did a build thread on it a while ago:

https://www.rx7club.com/build-thread...a-8-fb-992844/

 

nice build on the Toy rear, it is amazing how afordable the gears and lockers are for a Toy 8 rear

 

toyota G series diff conversion for early rotors is common in oz
( all our hilux toyotas get a G diff, though i believe in the US you often get the weaker F )

very hard to break unless you have 400 rwhp and lots of grip
best i have managed is to undo the nut on the pinion

they have 30 spline axles and are the equiv to the b1600/ 2000 diffs for strength , but easier to get different ratios for

 

In order to run sub 14's you need to replace your 12a with a rb20det lol
If I had slicks and a rear end I'd see 12's.
Really you just need a good sized turbo. Boost will get anything sub 14's Turbos and carbs don't always go together mind you.

BT

 

thanks a lot would like to see some pictures of your setup

 

Check My build thread at top of page erick

BT

 

I should learn to shut up.