notveryhappyjack

iTrader: (4)

I'm running into a slight problem with breaking differentials. My turbo car has to much power and decided to shred my differential. Is there any replacement or does any one have advice on how to make the gsl se or gsl differential stronger.

note I need the 84-5 year big flange diff.

thanks

Jeezus

iTrader: (4)

How much power are you making?

steve84GS TII

How are you treating it!?
There is no reason to try and "beef" up the stock diff.If you want to be able to beat on it, or you are really making a lot of power,then just upgrade to a Ford 8.8" rearend.If youve spent enough money on HP to truely justify the need for an 8.8",then the cost of the upgrade should be acceptable.
If your rearend is failing due to hard launches or drifting,then you just need to be kinder to it.FWIW,Ive yet to break a stock rearend in my car in over 7 years of daily driving with a ported S5 TII engine.

dbragg

iTrader: (7)

get a lower gear ratio? cryo treat the ring and pinion? are you blowing the LSD? get a kaaz.

notveryhappyjack

iTrader: (4)

I usually treat it nice. I have only actually lanched it once and rarely drift it (thats what the 85 is for)

I forgot to warm up the trans/rear end before I hit boost. When boost hit it chipped the teeth and about 5 mins after that it I was boosting 2nd and it completely broke about 10-15 teeth and chipped the rest, the outside temp was around 35 f. And now i know I need to warm the whole car up more before boost.

Power is somewhere around 320-350 at the wheels with the profec on hi setting. I was told by Steve Kan, the dyno he tuned my car on read 10-15% conservative. Actual dyno sheet read 303 at the wheels so add 10-15% and that is what it actually has. On the 19th there is a dyno day I'm trying to make and find out for real what numbers it makes on a dynojet.

notveryhappyjack

iTrader: (4)

I don't believe I broke the actual lsd unit. I pulled out the diff and looked inside and the pinion gear I think (bigest one inside) ???? was missing many teeth and a bunch were chipped also.

I was talking with z-beater about cryo treating his since he is about to push 16psi later this year. Maybe that is something I should look into. AWS do you know of any sites I could read more about this topic?

Siraniko

iTrader: (13)

breaking teeth coz the GSL-SE have finer teeth. You should switch to a regular GSL 3rd member which is much stronger.

Slammed_GSL

iTrader: (14)

Couple of Archive posts that might or might not help.

https://www.rx7club.com/1st-gen-archive-71/drivetrain-miata-diff-interchange-into-84-85-models-695127/
https://www.rx7club.com/1st-gen-archive-71/drivetrain-how-rebuild-your-lsd-711948/

Didn't know about the tooth count difference between the GSL and GSL-SE.
Can you swap the Ring and Pinion set between the two models?

steve84GS TII

More than likely,your bearings are worn which is causing excess gear deflection under power, which opens up the backlash and causes the gears to ride up on the thinner upper portions of each tooth.That explains the chipped teeth, although they could have been busted by debris from the fully broken off teeth.

Our rearends are plenty strong when healthy.Unfortunately,too many 1st gens have FAR too many miles on their drivetrain already, when high HP engines are installed.Before you spend big bucks on cryo treatment and other stuff,get another unit and rebuild it fully.Its not expensive, or particularly difficult to do.Either have a shop do it or use my two posts to rebuild the LSD to its full potential and put the rearend back to new specs.In proper condition,you should be breaking axle shafts well before you pop ring and pinions.Thats why Moser and others makes beefier axles,but nobody sells upgraded strength gearsets.

notveryhappyjack

iTrader: (4)

steve, I would like links to your posts when you got a free moment.

The car already has mosler axles in it and they looked new when I pulled them out. Anything to do with the rear end is new since last winter, barrings, seals ect.

Vashner

lol that's a cool problem to have. :0

I think I had seen the other day on Dallas craigslist a FB with a 350 chevy and dude also had GM tranny and DIf installed.

steve84GS TII

The rearend outta be able to hold the numbers your putting down.
But if it was all rebuilt and your sure it was done right,then its probably time for an upgrade.

Here are the two links,one for the LSD rebuild and one for setting up gears/bearings.

https://www.rx7club.com/1st-generation-specific-1979-1985-18/gsl-se-lsd-teardown-pics-drivetrain-tutorials-coming-soon-707958/
https://www.rx7club.com/showthread.php?t=711948

Vashner

Also was that diff using the good red racing LSD gear oil it's entire life? That could of been a factor if prior owner ran it with stock juice. I swear this 84 gs.. the diff gear oil was literally the factory oil from Japan 1984. It was like water and dirt.

Also when it's brand new you should swap out the oil after break in to get metal shavings and junk out.

dbragg

iTrader: (7)

i was informed by someone of a race teamin NY running a drag first gen on a stock rearend. they swapped in some ring and pinion from some older mazda to give them a 3.62 IIRC.

what wacky is saying is right. the GSL 3rd members are stronger. you need to find one, rebuild it, and you should be good to go. i think ill swap out my SE 3rd member for my GSL one on that note.

mikewoodkozar

That sucks man. The ford 9" rears are very impressive, yet they all seem kind of intimidating in price and skill to install Hope the GSL rearend works!

Jeff20B

iTrader: (13)

Chris broke things in that car too. It's probably due to the 6 puck disc. Steve will recommend the HD disc from Racing Beat. It is a full faced organic disc with no springy marcels between the friction surfaces. It is very easy to drive and will work great with the ACT pressure plate that's already in the car. This disc will save trannies and differentials.

z-beater

I think that Chris changed the 6 puck out a few months before he sold it. He maintained that car religiously. I think that he went through 3-4 rearends. In addition to having moser axles it was also braced. I am not sure why that car has such problems with rear-ends. It always seemed like it would lose traction first.

There have been a lot of interesting talks in the last few years about diffs. People are starting to make some real power now and publically sharing their "secrets". For me a 8.8 is not really an option. The ford unit is 80-100lbs more and has a higher drivetrain loss. If I drag raced more it might be a viable option.

My car is primarily used for street cruising with the occasional auto-x/drag. And I find that the SE's first gear is too short. So I think that the GSL's gears will be perfect for my application.

Here is what I plan: 84-85 GSL pumpkin(cryo treated), braced rear-end, moser axles, new bearings etc.

Any other high hp 1st gens out there that are succesfully putting down power on a modified OEM unit?

dbragg

iTrader: (7)

^^ i agree. but if i HAD to go with another, i think id go with a toyota 8"

aussiesmg

iTrader: (1)

SE axles fit into GSL housing with the 3.9 pumpkin, so you can keep the brakes and 114.3 stud pattern, my car runs a GSL diff along with the GSL-SE axles and brakes, you will need the GSL-SE handbrake cables

notveryhappyjack

iTrader: (4)

I got the diff pulled out and it seems the pinion gear broke first and then proceeded to break the ring gear in the few seconds that followed.

pics of the carnage, I broke about half of the pinion teeth and maybe 1/4 of the ring teeth are either chipped or broke off fully.




Here is the replacement, GSL-SE differential. New and never installed on a car so the seller said.

notveryhappyjack

iTrader: (4)

Im having a hard time removing the pinion seal so I can reuse my T2 flange and seal. Does anyone have a better idea then prying with a screwdriver ? I have hear of seal puller????s don't know what they look like or where to find them.

dbragg

iTrader: (7)

did you loosen the big nut on the 3rd member where the driveshaft bolts up? if so, did you reset the back lash?

you need a GSL diff, not that SE diff

rotaryB-2000

..this is a nice setup for an se.
http://www.toyota3tc.com/forum/viewtopic.php?t=15659
Wicked..I want one...........

steve84GS TII

When I did my rearend rebuild last month,I switched to GSL gears......cant say it made a hell of a lot of difference.Sure,its a tad taller than the SE's gears,but my 245-17's still dont stand a chance of holding traction in 1st and most of 2nd.1st gear goes by in a flash,so I just shift quickly and I feather it a little in 2nd when she starts to walk sidways.

Id be interested in seeing your pinion bearing condition and your current backlash settings.

Ive always run the fine pitch gears with no problems.Since the coarse gears were in older cars,I cant imagine the finer gears would be weaker.More than likely they switched to quiet things down.I have no proof that one it stronger than another,but the sliding nature of hypoid gears seems such that having more teeth would increase the continuous contact area between the pinion and ring,helping to distribute the load.Coarser teeth might be thicker at the root,but the contact area is higher up, on the thinner part of the tooth anyways.Contact spread across more teeth means that less stress is taken up by each individual tooth and they can be thinner without being weaker as a whole.

z-beater

I agree with the load distribution Steve. What tires you running? Also what are the widths of your wheels? I would assume 8-8.5".

Sorry about the thread jack Aaron, looks like you are making good progress.