Hello, I bought a 83 gsl fb this winter and I’m looking to make it in a circuit/ drift car. I read a lot on here about people doing a Ford 8.8 rear end swap and I was wondering if that would be overkill for what I have in mind. Not looking to make too much power. Would it be smarter to just upgrade to the stronger gsl-le rear end and lsd or go all out and use the Ford 8.8?

 

welcome to the board.

this is my opinion, so get your grain of salt. also, i'm not into drifting, so there's that as well.

as far as i see it, the only real upside to getting the Ford rear is perhaps the available gearing (wheel/tire choices, too), but i would think that's about it. if you're not planning to put a lot of power down, then it may not be worth your while.

as for GSL vs. GSL-SE: https://www.rx7club.com/1st-generati...ar-end-430431/

i, personally, have driven with both, it's not a night and day thing. so i'd say use what you have, maybe try to have it rebuilt so you know what's what, but other than that, do what you feel you have to do.

EDIT
also, PM one of the moderators for this and have them move it out of the Build threads sub-section.

 

Ok! Thank you!

 

Ring and Pinion gears are the same across all SA/FB RX7 differentials. You can also use the Ring and Pinion/differential from 1.8L Miatas through 2005. There are are also some fitments from the KIA Sportage 4x4 (front diff) and the Honda S2000.

The OE clutch type limited slip diff is also the same across all years although the side gears in the differentials are different from 79-83 and 84-85 because the 84-85 have bigger axles with a different spline count. Side gears are interchangeable so you can use an earlier diff in an 84-85 if you change them. You can also fit torsen diffs from a 1.8L Miata through 2005 and there are aftermarket units out there as well.

Gear ratio choices are some what limited. OE 3.90, 4.10 are pretty common. In the Miata you can find some 4.30 gears and I can typically find a 4.78 on ebay when I need one. Beyond that after market ring and pinions ratios (4.44 and 5.12) are spendy and I am only seeing them in Australia. The ratio you need will be dependent on the transmission gear you will be in when you are making a run, the power band of your engine and the tire diameter you are using.

Strength wise, the OE stuff - ring and pinion and differential are pretty strong. However the OE axle housing and the OE axle bearing are not very strong. To me the axle bearing are the biggest problem because they don't handle high side loads (like from sticky tires).

 

GSL-SE are not stronger. The axle housings are fairly weak.

IMO there are so many things wrong with the FB with regards to drift, and the cars/parts are getting so expensive and hard to find, you're probably better off getting a FRS/BRZ. You can find them with body damage or hurt engines for like $7000 now.

 

Hey guys, back with more questions… I’ve decided to keep the rear end I've got but I was just wondering if I can upgrade to stronger parts or do I need to buy a 1984-85 full assembly to upgrade. I’m planning on using a kaaz 1.5 way lsd, moser rear axles with 4x114.3 pattern, and a racing beat rack and pinion. For brakes I was gonna use technotoytunings micro big brake kit to get the rear vented disks. Will these fit into my s2 1983 axle housing or do I need to buy a s3 housing? Thanks.
-Cole.

 

If your doing all that work to an RX-7 diff/axle, just get the Ford 8.8 and chop it down.

 

The GSL-SE rearend is weaker, not stronger.

The strongest combination of parts is probably a '79-83 rearend. It LOOKS like you might be able to have custom axles made that have the small bearing on the outside and 26 spline on the inside, because 24 spline diff parts for the '79-83 are REALLY hard to find, 26 spline is popular because it is used in Miatas.

The weak point is not the axles. The weak point is the rearend housing flexing, which causes the axles to flex. Eventually the constant gyrating will thin down the axle where the bearings are pressed on. The '84-85 rearend has a weaker housing than the '79-83. I used to use a braced '84-85 housing (GSL and GSL-SE are the same part), but still had to swap out axles regularly because of the bearing issues. I broke a brace once when the jack slipped, and broke that side's axle at the splines within five runs.

Note that people run Miatas with 300hp turbo engines, 400+hp V8s, and they have the same size OR SMALLER axles and they don't have axle problems.

The ultimate would be a floater axle conversion. For the money, it's waaaay easier/cheaper to go with a Ford 7.5 or 8.8, use Ford 9" ends on it, and have axles made to your specs. I have a 9", because it cost about as much to put together as buying two RX-7 rearends to tear up.

All for a car that is absolutely horrible for drift because of all sorts of suspension geometry issues. By the time you sort all that out, you could have bought an FR-S...