ducktape

"You've got a clutch type LSD that will never break"
-Philip_G

The problem; Exploding differentials. (Video, 4.3mb)

The solution:


Compared:




Installing:






Wheel-fit testing:








The 15's barely clear the brakes. The Mickey's fit nicely in the wells, tho. Pretty Dirte'

KeloidJonesJr.

iTrader: (8)

Looks GOOD!

ducktape

Thanks. 8)

I can't wait to get some runs in on it.

snub disphenoid

Buncha questions because I'm going to be pushing 400hp+ and it certainly isn't going to be going through my GSL rear end. How much did it cost, what gears did you use, how much fabrication is involved and how long did it take to get the parts/how easy were they to find?

Jesuscookies

iTrader: (1)

Looks good. I am actually doing this same conversion, but into an RX2.

Let me ask you, why didn't you have the axle tubes welded in?

Those 3 pins are not very strong when doing drag launches.

also did you end up shortening yours? or did you find one with a similar measurement as the RX7?

ducktape

I've found the GSL third-members (with Limited-Slip) are pretty stout for what they are. They have one more clutch than the GSL-SE center-sections, and will tolerate around 300hp on the street as long as you don't abuse them too much. Once you take it to the track tho, it's all over. Try to launch on slicks or drag radials and you'll be going home on a roll-back too.

The Mazda diff pictured above is actually from GSL and managed to survive about 4 months of my abuse without breaking. As far as I'm concerned, that's downright heroic.

The only low-buck option I was able to make work was to find an open big-axle third-member (Also from a GSL), and have the spider-gears welded. In this way, it worked like a spool with both wheels traveling at the same speed all the time. I bought an axle-puller, and on track days would pull the third-member out and stuff the welded one in. It got really tedious changing the diff every weekend, so I commissioned a local shop to help me build this 8.8.

A little over $2500 all-told. That's a non-typical price for this item. Granny's makes a bolt-in 8.8 kit for around a grand, but I had some specific goals and couldn't trust a near-stock rear-end for my application.

The housing was narrowed to match the original width of the stock Mazda GSL-SE rear-end (approximately 58-1/8 inches). The original mounting points were cut from a GSL-model differential, installed and reinforced with plate-steel. Labor-cost was pretty intense, and I would suggest keeping the original width of the 8.8 if you're on a budget.

I used a 4.10 gear, specifically because it seems to be good for the hole-shot without having to run through all 5 gears to get to the end of the track (w/ TII tranny).

I purchased an Auburn "ECTED" LSD/Locker from Jegs at a cost of around $550. This unit features tool-steel spider gears and carbon-fibre clutches, and has the ability to operate as a Limited Slip differential as well as an electric "Locker". I chose this unit because I intend to street the car, and Auburn seems to have a good reputation. Even tho this diff has been used on street Mustangs running faster than 11's, it is still considered to be a half-measure by some. I will probably have to rebuild it eventually, where as a spool is lightweight and will never break in the way a differential will. Did I mention it's also warranteed for quite a while?

The brakes are made by Aerospace, and cost around $450. I would recommend using the factory drums as a budget measure. These brakes require new brake lines and do not include the trappings necessary for a parking brake.

The Stainless axles are made by Strange, and are highly recommended. C-clip eliminators are in use.

The diff-cover is reinforced billet aluminum from Ford Racing. It costs around $130, and is recommended for people who are in the habit of breaking rear-ends.

The assembly is about 40lbs heavier than stock, fits like a glove and looks like it was meant to be there. I can't wait to give it hell.

z-beater

Very nice install. What kind of hp are you pushing? 4 months is awesome for the stocker.

ducktape

Made somewhere in the neighborhood of 300-350 last season with a SP S4 TII motor and a t04.

The new motor is still under construction, but should be done soon. This season, the sky is the limit...

ducktape

Thanks for the sanity-check. I'll get that fixed before the car rolls.

Michael_Rudy

Good Lord, what size of turbo is that?

z-beater

Looks like a gt45-45. Kind of hard to tell from the pictures though.

I love the motor!

Looks like you have a death wish

rex3

iTrader: (2)

Jesuscookies what did you have to do to get the 8.8 to fit your car. I have to put one in my car.
My car 74 Rx2
13BRE Cosmo
Turbonetics T66
Haltech E6X
and yea BF Goodrich drag radials with stock posi rear ready to explode.

Jesuscookies

iTrader: (1)

I PM'd you.

EL5Letra

uh....where did you get that diff. ?

rmriggin

8.8s are common and easy to find at wrecking yards. Not to mention they are pretty cheap too. The spendy part would be building one up if it didn't have posi already. Can't go wrong with an 8.8 though.

southernrunner

So what did you have to do to make it fit? There is no way it just bolted up. If so......lucky bastard. That thing is way to clean for you to get from a junk yard. Where did you buy it from? Nice work though man, car looks awesome.

EL5Letra

i have never seen such a clean diff, liek that in a junkyard...i reckon LOL he worked on it a little .

ducktape

No junkyard parts. I described the build-up pretty well here.

The shop that did all the work is called "No-Limit Motorsports". They do a lot custom fab for drag cars (mostly domestic).

Jesuscookies

iTrader: (1)

If you know what you are looking for they are very easy to find, and cheap to boot. As rmriggin mentioned, the real cost is in having them built up.

Many Ford's come with an 8.8. However, the one that seems to have the most potential is the ford explorer rear end.

I picked up a 96 explorer rear end for $225, with a 31 spline big bearing limited slip posi, 11 inch disc brakes, 5 X 114.3 bolt pattern, and 4.11 gears. It will cost another $1500 to build it to my specs.

Mustangs are another car that the 8.8 is on. However, they are 28 spline, so you will need to switch out the bearings if you want 31spline, and most are drum brake, which means you will be paying to uprgrade that as well.

jamespond24

iTrader: (13)

Thank you for the useful infomation jesuscookies. I now know which rearend to use in my GSL-SE TII swap.

LUPE

I used a Mustang GT 8.8 .

8.8 Rear end $50
Wilwood Rear Brake Kit $850
FMS 4.30 gears $200
Moser 31 Spline w/c-clip eliminators $500
8.8 FMS differential $450

Plus all of the 4 link components.

Directfreak

iTrader: (2)

Your setup and mine are almost Identical. Same rear, same spool, same brakes, same cover, etc.

I ended up doing a 4 link with coil overs, but I REALLY wanted to use the stock mounting points and brackets like you did. Unfortunately the crackhead working on my car at the time thought he knew what I wanted, rather than to listening to me period.

I chose slightly different gears since mine is 95% street car though. And I am going to swap my rear 4-piston Aerospace brakes for some TII ones.
My Brake Pedal Travel is annoyingly long, even though we've already upgraded the master, etc.

I look forward to seeing some HP and track numbers from your ride.
Congrats

ducktape

Mind if I ask what you did for the brake lines? I'm probably going to keep the stock y-block and run some custom braided lines from the block to each caliper. Did you end up using a proportioning valve for the rear?

Did you keep the stock sway bar? What did you use for a panhard rod? How do you like the ECTED? Have you made any runs on slicks with it?

Thanks for the comments, I'm looking forward to hammering on it with impunity.

Directfreak

iTrader: (2)

Yep. Still sucks. I even got a HUGE Master. It's just too much brakes in the rear. I have TII brakes in the front too.

I used a straight bar across the back with pillow ball mounts. That's with the 4 link. With your setup, the stock setup should be fine if you remove the bushings and replace them with adjustable mounts.

No slicks runs yet, just BFG drag radials. I need to adjust the rear still as it is whining.

1sgen

iTrader: (1)

updating bump?