Sheptrans doing 4 spider upgrade for automatics

[GDNF2ET]

This is in reference to the automatic center-dif, which is different from the manual center-dif..They did mine a couple months ago and was the best price I found, plus you can't beat their reputation.... When you start making power, a welded center or 4 spider upgrade is a must...

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[TSimage]

This is the first I have heard of needing either at powerlevels far beyond a HTA68.

Interesting to know however. Thanks for the heads up.

 

[transdude]

A four spider center diff with a viscous coupler incapable of of biasing the torque front to rear is not very useful.

Welded is the only solution in my opinion.

-John
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[definitiveno]

How does welded behave? Is it terrible for a street car?

 

[jrohner]

How does welded behave? Is it terrible for a street car?

For an automatic it might not be as bad; I hated it in my 5 speed car.

 

[HighPSI TSi Guy]

For an automatic it might not be as bad; I hated it in my 5 speed car.

In my opinion, it's just as bad.

 

[transdude]

Driving with a welded center isn't bad at all and I'm 100% sure that it beats driving with a broken one.

-John
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[badas93tsi]

It's like driving a 4 wheel drive truck in low 4wd. It wasnt bad unless you're in tight parking lots, or trying to make a tight turn. My 5spd setup with a spool acted the exact same way. My Camaro that I have now has a spool, and it's the same way. It's something you have to get used to, but worth the benefits.

 

[HighPSI TSi Guy]

Driving with a welded center isn't bad at all and I'm 100% sure that it beats driving with a broken one.

-John
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For a weekend car I agree. But for a daily driver it's nice to be able to do a U-turn with less than 5 lanes. Hell I have to 3 point turn out of my driveway with the welded diff, 4 point turn if I want to clear the mailbox by more than 1 foot.

4 spider will hold power as long as you aren't wheel-hopping down the track, the only thing I would question would be the VC ability to handle high torque on the line with weak rear brakes.

I guess with these cars you really just have to make a choice - do you want to break transfer cases or do you want to break diffs. Open diff saves Xfer cases, but risks the diff, locked diff saves the diff but risks transfer cases.

Out of all the things I've done to the car over the years, I feel the welded diff is the only thing that actually reduced driveability quality.

 

[94awdcoupe]

I agree welded centers are fine for drag use. But 100% suck for street cars. retaining the factory viscous would be only route for me.

I have a theory about broken centers from rebuilding some 100 trans or so. That theory is the factory center gears are greatly weakened when the end washer that supports the end cap gear gets burned up. At that point there is too much play in the factory spider set. This makes the diff week. I would say 80% of the AWD trans I have opened have too much play in them. and therefore a weakened center diff. This is because 80% of the AWD cars on the planet suffer from some ricer who gets behind the wheel and spins the tires . The factory center was never designed to survive from these antics. That small thin washer heats up and self destructs.

I have been running a factory 2 spider in my evo 1 for about 5 years now with just torrington bearing upgrade. I added screens to the outside of diff housing in case it does break. I didnt want a broken diff to contaminate the trans. This way if the diff broke it could be replaced on the car without removing tranny.

It has held just fine. My car makes a ton of torque for a street car. Its had 2.3 with 20g for most of that time. It now has a 2.3 HTA 73. The front end lifts and the car twists sideways when the torque hits .

 

[transdude]

For a weekend car I agree. But for a daily driver it's nice to be able to do a U-turn with less than 5 lanes. Hell I have to 3 point turn out of my driveway with the welded diff, 4 point turn if I want to clear the mailbox by more than 1 foot.

4 spider will hold power as long as you aren't wheel-hopping down the track, the only thing I would question would be the VC ability to handle high torque on the line with weak rear brakes.

I guess with these cars you really just have to make a choice - do you want to break transfer cases or do you want to break diffs. Open diff saves Xfer cases, but risks the diff, locked diff saves the diff but risks transfer cases.

Out of all the things I've done to the car over the years, I feel the welded diff is the only thing that actually reduced driveability quality.

4 spiders going to fast because they are not being controlled by the viscous will fail every bit as quickly as 2. They kind of weld themselves to the diff case.

That said, I personally haven't seen a single auto with a welded diff break a transfer case, if I am understanding your post correctly.

As an aside, a center diff that fails badly can also grenade the trans due to the amount of metal that can be generated.

-John
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[HighPSI TSi Guy]

4 spiders going to fast because they are not being controlled by the viscous will fail every bit as quickly as 2. They kind of weld themselves to the diff case.

That said, I personally haven't seen a single auto with a welded diff break a transfer case, if I am understanding your post correctly.

As an aside, a center diff that fails badly can also grenade the trans due to the amount of metal that can be generated.

-John
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I see what you're saying, that is agreeing with what myself and 94awdcoupe said. The diff fails because the viscous slips too much and causes the bushings to wear. The torrington bearing is probably more important than the extra spider gears in my opinion. If the viscous is working and the bushings stay in working order, the only thing that will damage the diff is tire shake or wheel-hop, most likely. The torrington bearing fixes the bushing wear problem.

I also agree that on an auto the risk is much higher at the diff due to the design, it is much more likely to spread destruction throughout the trans, and most likely cause case failure, than in a 5 speed.

As far as transfer case breakage, I've seen it plenty of times. It happens for the same reason it does in a 5 speed. Traction variance from front to rear putting too much load on the shaft. When the front tires spin, and rear tires plant, and the viscous isn't there to take the beating, the stress goes to the transfer case and rips it apart. It is much more rare on an auto, but it does happen especially with the stroker cars if launched too hard.

 

[talondave]

I don't see what the problem is, I have no complains about street driving with a welded diff!!!

 

[dsmusmc]

I have a welded center dif. in my Shep stage4 and plan to have one once I go auto. I dont have trouble at all with street driving and I think its not as bad as people make it out to be. It way chirp alittle when turning off streets but nothing horrible like when going up and down a parking lot looking for a spot. Im not lazy so I just park in the back where I dont have to make abunch of turns and keeps idiots from parking next to my car. IMO when you start getting into high HP its the best option.

 

[99gst_racer]

I don't see what the problem is, I have no complains about street driving with a welded diff!!!

Same here. Been street driving on one for 4 years. I get excellent traction and I haven't had a single drivetrain failure. I only feel that it's there during a full-lock turn, and that only requires a bit more throttle to overcome it.

A front-rear lock on an AWD is not near as difficult to manage as a left-right lock on a 4x4 truck.

 

[donniekak]

Driving with a welded center isn't bad at all and I'm 100% sure that it beats driving with a broken one.

-John
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It was the most no brainer compromise i ever made with my dsm. Drive with the small, and they are small inconveniences of a welded center. Or replace a center diff, and the resulting damage to the rest of the trans, very often. I also broke fewer rear axles with the welded diff, as the power wasn't being transfered front to back and repeatedly shocking the driveline. The welded center diff is a smoother launch.
Here is what an open diff does to your driveline.
YouTube - DSM LAUNCH SLOW MOTION
Here is a welded diff.
YouTube - DSM Slo-Mo Launch Welded Center Diff

 

[talondave]

Same here. Been street driving on one for 4 years. I get excellent traction and I haven't had a single drivetrain failure. I only feel that it's there during a full-lock turn, and that only requires a bit more throttle to overcome it.

A front-rear lock on an AWD is not near as difficult to manage as a left-right lock on a 4x4 truck.

I agree, my truck in 4wd is terrible on pavement, and gravel!!!

 

[autotalon]

Can the welded center be changed with the trans still in the car? I doubt I need it for my power level, but I am spinning all 4 on dry pavement with a 25psi launch.

 

[dsmmack]

Can the welded center be changed with the trans still in the car? .

Yes.

 

[HighPSI TSi Guy]

Yes.

Not on an auto. I wouldn't try it at least.

 

[dsmmack]

Not on an auto. I wouldn't try it at least.

Ive pulled my center diff out with the trans in the car before.

 

[97gst_spyder]

How is the Torrington bearing upgrade done? Can it be done when the trans is in the car?