Center Differential Specific

[megadan]

My tranny is apart. When I opened my center differential, I found that both spider gears were ok but the shaft that goes with the spyder gear is chew (no more gear on it).
The shaft i'm talking about is the one that enter the center diff. and to other end goes to the viscous coupler.

The question is what are the less expensive options left to me considering I want 50/50 power front/rear.

I found this http://www.slowboyracing.com/more.php?id=2454& at SBR (Team R.I.P. TRE-spec Center Differential Spool)

What is the difference between welded differential and the spool from SBR.
Are the two options available to me (welded or spool) considering my no more gear shaft?

 

[4pistons]

A spool and a welded diff act the same way. A spool you have to buy and install. To weld the diff you use what you have already. A spool can be changed. Welding is permanent, unless you change out the whole diff.

To weld your diff you need to keep the side gear so the splines engage the VC or a VCE, if you're using one. The TRE Spool looks like it replaces the side gears. Nice piece, btw.

Check out my diff welding article http://www.dsmtuners.com/forums/showthread.php?t=173481

Rick - '91 GSX

 

[megadan]

thanks for the reply.
So in the picture here: http://www.dsmtuners.com/forums/showthread.php?t=173481
the number 6 is the part that has no more teeth on the gear side. Will the spool work anyway?

 

[jtmcinder]

The question is what are the less expensive options left to me considering I want 50/50 power front/rear.

As I just wrote in a comment on the tech article cited above, a locked center does not provide a 50/50 "power" split. It merely forces the front and rear wheels to turn the same speed. Sometimes this will result in a 50/50 torque split; other times it could result in a 100/0 or 0/100 torque split (such as when one end of the car is on a frictionless surface), because a locked center has the ability to bias torque distribution completely.

Related to the above, if drag-racing is your hobby, why would you want a 50/50 torque split in the first place? During a hard launch, your weight distribution is highly shifted to the rear. Thus, a torque split that is equally biased to the rear would be best.

- Jtoby

 

[pimpngear]

I am by no means an expert, but your #6 piece from the diagram above is what is welded to the rear case half. This is what I derived from looking at this pic:

http://www.teamrip.com/largecdiff.jpg

So it appears that in your case, if that shaft's gear (not spline) is destroyed you won't be able to run a spool or a welded dif without first replacing that side gear. I have never pulled a center dif apart before, so an experienced opinion would be helpful...any takers?

-Rob

 

[jtmcinder]

As long as there is enough of the side gear to weld it to the case, you'll be fine. You don't need the teeth of of the sidegears because power no longer goes to the outputs via the spider-gear-to-side-gear interface; in a welder diff, the power goes directly from the case to the side gears and, therefore, the output. That's why you delete the spider and the spider gears after the welding.

In contrast, the splines on the side gears must be intact, because these are what transfer the power to the output shafts.

Or am I misunderstanding your point?

- Jtoby

 

[pimpngear]

Nope..you didn't misunderstand my point at all. I agree about the sline locking into the output shaft. I just wish I could look at a sideview shot of the completed (welded) unit... by the graphic above, it appears that onece the spider and spider gears are removed gear #10 and gear #6 mesh together and turn as one unit.....but that obviously isn't possible (or is it)....so where does the direct coupling of the newly welded pieces happen? Sorry for beating a dead horse.

-Rob

 

[jtmcinder]

My guess is that this is a useful conversation for lurkers, so no worries.

#6 and #10 remain separated by the width of the spider gear, even in a welded diff. The reason why #6 and #10 are solidly connected is that both are welded to halves of the case and the entire case (once bolted back together) always turns as a unit. One half of the case turns the front output; the other half of the case turns the rear output.

I suppose you could leave the spider and spider gears in there if you really wanted to. I wouldn't.

- Jtoby

 

[megadan]

Splines of the shaft are ok but teeth are destroyed. I wanted 50/50 and not all to the rear because of the snow we have in Quebec. I tought it would help to have all wheel still pushig the ground.

 

[jtmcinder]

It is misleading to speak of a welded center as 50/50. It is not a differential any more, so it does not have a torque split. In fact, because a welded center has the ability to bias torque completely, at various times it is anything from 100/0 to 0/100. Of course, when you have very low grip (ice), the ability to bias torque is very useful, so take this as a point on semantics and not a suggestion not to do it.

- Jtoby

 

[pneumo]

I wanted 50/50 and not all to the rear because of the snow we have in Quebec. I thought it would help to have all wheel still pushig the ground.

I've read several reports of bad handling in the snow with a welded center diff. Here's one: www.dsmtuners.com/forums/showpost.php?p=1695507&postcount=13

 

[megadan]

Can I weld the center diff myself with a rod welding machine or I need Ni welding?

 

[4pistons]

Take it to someone who knows how to weld hardened gears. If it isn't done correctly the gears will crack and possibly fail destroying your diff, and maybe the whole tranny. Is that really worth trying to be cheap?

Rick - '91 GSX

 

[4pistons]

I tought it would help to have all wheel still pushig the ground.

?????

Rick - '91 GSX

 

[megadan]

Yeah I know. My english is not perfect but I do my best. I meant that as we have snow, It is easier when the car is all wheel drive. Just forget about it.

I'll have the welding done by a pro as you suggested.

 

[raped]

be careful when you weld the bottom gear to the case, it must be perfectly centered.