First off, I am admitting I have very little drivetrain knowledge. So please be patient if my questions

Questions or input needed:

I have a 98 gsx, 350bhp, 300 torque and running a ACT2600. Nothing impressive, however I just discovered 2step a few weeks ago, when using 2step off the line, I have a nagging feeling I am on borrowed time with the center diff/trans/axles.

I have only launched the car a handful of times (practicing on an old abandoned road). The 2step is set around 4500rpms, the FP Green I am running builds about 10psi, and I feather the clutch out. I will never dump the clutch, just feather it, and the car hooks and pulls like I have never felt before. I can feel the car want to break all 4 tires loose, so I back off in fear of damaging the drivetrain.

I have since been trying to research the weak points of the 2g drivetrain and found most say its the Center Diff, I read through a good amount of information, however most the threads are from 6 to 8 years ago. After reading, I came to the conclusion that I wanted the strongest Center Diff I can get without welding it. I found a lot of people used to run a 4 spider center diff from Speed Design, however I cant seem to find there site, I am not not even sure they are still in business?

I also found this: https://www.tmzperformance.com/shop/custom-4-spider-hardened-chromoly-cross-shaft-for-1990-1999-dsm/

I saw TMZ has a sale on their Center Diff options. Looks like they have a fully assembled center diff for sale, something that appeals to me because I do not have the knowledge or time to pull out my center diff and piece upgraded parts into it. I would like to drop in or have the local transmission shop drop in a new fully assembled unit.

Is anyone running a TMZ Center Diff?
Is Speed Design still in business?
Is there any other option that I should be considering; another company, welding the center diff, or anything else I am simply missing or misunderstanding?

Thanks for any help guys

If you don't want welding the center diff for the drivability, then 4 spider or LSD.

https://www.tmzperformance.com/shop/custom-4-spider-hardened-chromoly-cross-shaft-for-1990-1999-dsm/
http://whiteshedspeed.com/home/tech-articles/w5m33-center-differential/
https://www.jackstransmissions.com/my-cart/store-home/trans-parts/4-spider?limit=100

From the above list, go with the TMZ or White Shed Speed. I don't trust a machined OEM center diff cross-shaft as much as I trust the aftermarket part.

Thanks guys, the White Shed Speed unit looks very nice. Also has been proven on his car for 2 race seasons at 650whp, wow! Thanks for the info guys.

I run the Beyond Redline cross shaft from TMZ as well as extra machining for double thrust washer as per Tim's specs, has held everything I've thrown as it and is 10x more enjoyable to drive than a welded center diff. It has gone 1.52 60' in a 3300lbs with driver car and gone mid 10's. I've also added oil scoops to the housing to make sure everything is well lubricated.

I don't want to be a bearer of bad news, but unless you have a junk 4 bolt rear diff I can harvest parts out of, I can't do a center diff right now. I can't even find some spares for myself.

I'm trying to learn/figure out how to make my own cross shafts, but I'm also doing 6 million other things too, so It's on a long too do list. My brother needs one for his galant, so that might push it along a little bit.

bastarddsm said:

I don't want to be a bearer of bad news, but unless you have a junk 4 bolt rear diff I can harvest parts out of, I can't do a center diff right now. I can't even find some spares for myself.

Click to expand...

Gotcha, thanks for the heads up. I send you an email, but you just answered my question

jdxnc said:

I run the Beyond Redline cross shaft from TMZ as well as extra machining for double thrust washer as per Tim's specs, has held everything I've thrown as it and is 10x more enjoyable to drive than a welded center diff.

Click to expand...

Thanks for the info, another well proven setup!

bastarddsm said:

I don't want to be a bearer of bad news, but unless you have a junk 4 bolt rear diff I can harvest parts out of, I can't do a center diff right now.

Click to expand...

Is it possible to use a 3 bolt diff cross shaft? I haven't had one apart to check it's particular internals.

Not really. The pins are a different size than a 4 bolt and won't work. I did do one with a 3 bolt cross shaft, and it was a bunch of extra work, and not worth the liability.

Bummer, I was thinking the abundance of discarded 3 bolts might make it easier for parts. Oh well!

I know this post is old but Im looking to buy a 4 spider center diff, does anybody is selling one or do any of you guys know where can I purchase one, TMZ is not making them aswel as Jacks transmission. Plz I will really appreciate the info!

I just bought one from Jacks a little over 6 months ago.

-Daniel

I have 6 remaining 4 spider cross shafts on the shelf, but nothing else after the shop fire. Jon at TRE can still machine and assemble it. If you need spider gears, you will have to order those from Australia from NEAT gearboxes.

All upper and lower pinion oiling shims are obsolete, along with the OEM pinion gearset, center diff cover and diff housing. The Torrington bearing and thrust washers are still available from McMaster-Carr, among other places, and there are limited spider gear thrust washers remaining.

You will need to have an undamaged center diff to have the work done on it. The cover and housing , and upper / lower pinion gears cannot be damaged!

The Torrington bearing is this: https://www.mcmaster.com/5909K38/
The Torrington thrust washers are these: https://www.mcmaster.com/5909K52/

I normally machine the cover for around 0.096"-0.102" cut, then use the bearing and TWO thrust washers, and have it set up for around 0.006-0.009" upper pinion gear endplay.

Jon's email is [email protected] , he can do the machinework and has the parts for assembly including the Torrington bearing and thrust washers to use for the upper pinion gear, and some lower pinion oiling shims to work with.

The cross shaft can be purchased here:
https://www.tmzperformance.com/shop/custom-4-spider-hardened-chromoly-cross-shaft-for-1990-1999-dsm/

The spider gears from here, they are sold in pairs. I would recommend ordering 2 pairs if you have no idea what the condition of your parts are like.
http://neatgearboxes.com.au/
Email: Samuel- [email protected]

twicks69 said:

I have 6 remaining 4 spider cross shafts on the shelf, but nothing else after the shop fire. Jon at TRE can still machine and assemble it. If you need spider gears, you will have to order those from Australia from NEAT gearboxes.

All upper and lower pinion oiling shims are obsolete, along with the OEM pinion gearset, center diff cover and diff housing. The Torrington bearing and thrust washers are still available from McMaster-Carr, among other places, and there are limited spider gear thrust washers remaining.

You will need to have an undamaged center diff to have the work done on it. The cover and housing , and upper / lower pinion gears cannot be damaged!

The Torrington bearing is this: https://www.mcmaster.com/5909K38/
The Torrington thrust washers are these: https://www.mcmaster.com/5909K52/

I normally machine the cover for around 0.096"-0.102" cut, then use the bearing and TWO thrust washers, and have it set up for around 0.006-0.009" upper pinion gear endplay.

Jon's email is [email protected] , he can do the machinework and has the parts for assembly including the Torrington bearing and thrust washers to use for the upper pinion gear, and some lower pinion oiling shims to work with.

The cross shaft can be purchased here:
https://www.tmzperformance.com/shop/custom-4-spider-hardened-chromoly-cross-shaft-for-1990-1999-dsm/

The spider gears from here, they are sold in pairs. I would recommend ordering 2 pairs if you have no idea what the condition of your parts are like.
http://neatgearboxes.com.au/
Email: Samuel- [email protected]

Click to expand...

I already spoke with Torrington and they do not have the gears available. I tried to look everywhere and nobody seems to have the spider gears. My center diff is in good condition.

I already spoke with Jon at TRE and he is just waiting for the parts but no luck finding them! The cross shaft is the only part I know you have it available but not the gears!

UPDATE!!

CAN'T FIND THE GEARS JUST THE CROSS SHAFT!

ANY WELDED CENTER DIFF FOR SALE OR A 4SPIDER CENTER DIFF FOR SALE? IF THERE IS ANY BUILD TRANS FOR SALE LET ME KNOW!
PLEASE HELP CAN'T RISK MY TRANNY,

What year gearset is it? I have a 90 welded center diff and I also have some spider gears.

Mine is 95 GSX, if you want I can send you a DM so you can give me more info about the gears!

@twicks69 if I order your Chromoly shaft , the washers, and send two spider diffs (if I can't get new gears) so that you have the two extra gears can Jon make a 4 spider out of it?

I already purchase the gears out of @jdxnc and mine diff also, everything is on the way to Jon for him to build me the 4 spider diff!

Are the gears from 90 - 99 the same? Auto vs Manual? Just trying to ensure i find some spiders

90-99 5 speed are the same spider and pinion gears and diff cover. The housings and lower pinion oiling washers are different with 3 variations.

The auto center diff stuff is completely different.