How many people welded their center diff themselves?

[dsm5062]

I am curious to know how many people have welded their center diffs themselves with just a regular welder and had it hold fine with plenty of abuse? My reason for asking is I blew my center diff and got a replacement stock transmission and dont want to blow the center diff again so I was going to weld it. I already have the one that broke the side gears from the broken trans welded and assembled but i was wondering if I should put this in my transmission I just got in place of the stock diff or pull out the stock good diff and weld it then put it back in? I just dont want to grenade another stock one, but I also dont want to put in the welded one I welded myself and have it break because everyone seems to say it makes the gears fragile, but I also dont want to pull apart a good working trans and mess it up replacing the diff with the one from the other trans. Anybody with experience with this, or that is running a self welded center diff?

 

[dsm5062]

So nobody here has welded their own center diff?... everyone had them done professionally?

 

[4pistons]

I welded mine and it's held up over 12 years of daily driving, autocrossing, street bombing, and I drive it like I stole it!!

Here's my write up on how I did it. http://www.dsmtuners.com/forums/articles-drivetrain/173481-welding-center-diff-how-why.html

Rick - '91 GSX

 

[99gst_racer]

TRE is only 30 min down the road from me and they only charge $50 for it, so that's the route I took.

But I know John @ SIM did his own and it's been working great. http://www.dsmtuners.com/forums/152719618-post150.html

 

[GRNDSM]

It is relatively easy to weld, but why? It causes terrible drivability, poor handling and puts more stress on all of your RWD components (t-case and rear axles).

If it is your daily driver, which you just occasionally race, put in another stocker until you can afford a 4 spider gear upgrade. And in the mean time, do not do anything stupid and your stock diff will be fine.

 

[4pistons]

I respectfully disagree GRNDSM, and that's from an experience standpoint. I welded mine 12, or 13 (?) years ago, back when the only option was a Cusco $1400 unit, and I have over 100,000 miles on it. It does not handle poorly, the ONLY drawback is during slow, very tight turns. Any other time it is invisible.

Here's an in depth discussion http://www.dsmtuners.com/forums/dri...ne-have-welded-center-diff.html#post152150491

Check out this thread. Be sure to scroll to the slo-mo launch videos, it's amazing! Which axles do you think are getting more stressed?? http://www.dsmtuners.com/forums/drivetrain-tech/334915-welded-center-dif.html

With all that being said, is welding the best option?? No. If you can afford a posi diff that doesn't have the side thrust washers that'd be the way to go. The crappy, failure-prone thrust washers were the reason I welded mine. They failed TWICE on my car and wiped out the output shaft/xfer case splines both times. Maybe if I didn't have to replace those I could have afforded the Cusco!

To dsm5062: You can't just weld the gears at home if you're not an experinced welder. The hardened gears must be brought up to temparature, welded securely, and slowly cooled or they will crack. It's not something to fool around with. Take it to a competent welder.

Rick - '91 GSX

 

[bryanwheat]

I've done a few. To do it right you have to tack it together with the diff in the tranny to line it up perfectly. IF you don't than it won't fit correctly. I just used a 140 amp gas mig.

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[99gst_racer]

I respectfully disagree GRNDSM, and that's from an experience standpoint. I welded mine 12, or 13 (?) years ago, back when the only option was a Cusco $1400 unit, and I have over 100,000 miles on it. It does not handle poorly, the ONLY drawback is during slow, very tight turns. Any other time it is invisible.

I agree with your disagreeance. I've been street driving on a welded center diff for over 4 years now, and I love it. In my car, it's hardly even noticeable. As with any other performance part that has some sort of small drawback or downside, you quickly adapt and driving with it becomes second nature. The only time my welded diff really makes itself apparent is during a full-lock turn while in reverse. And that's usually only while backing out of my driveway. Aside from that very minor inconvenience, it's been an excellent addition to my car, and saved me a good chunk of change over a 4-spider. I've also never had one single drivetrain failure in the 4+ years that I've used it.

 

[GRNDSM]

Rick, our disagreement goes back 6 years!

http://www.dsmtuners.com/forums/drivetrain-tech/193255-welded-center-diff-daily-driver.html

(I am glad that eventually that poll swung in the right direction!)

So I was expecting your rebuttal BTW, Speed Design was making their $500, 4 spider center diffs since 97/98. So you didn't have to shell out $1400 for Cusco.

If you guys do not mind all the noises from your unnecessarily stressed drivetrain/tires are making and diminished handling, then go for it!

I must be a handling snob, because it drives me crazy! BTW, one of our locals didn't follow my advice to swap in a VC for better handling and raced at on oval track. He ended up totaling the car against a cement wall...

But looking at that 6 year old thread, I will add that I will no-longer recommend using a VCE for drag racing "fast" cars. I can't define "fast", as it is more of a function of how much torque you are making. But after seeing VCE shearing off a center diff cover and then causing major carnage, I would stick with welding/spool as the preferred methods of achieving 4x4. VCE's can still be used for dyno testing AWD cars on a 2WD dyno and on "slow" drag cars.

 

[GRNDSM]

I've done a few. To do it right you have to tack it together with the diff in the tranny to line it up perfectly. IF you don't than it won't fit correctly. I just used a 140 amp gas mig.

Bryan, this will not hurt, but it is simply not neccessary! Or if it was, you could never exchange welded diffs between two trannies (people do that all the time).

 

[bryanwheat]

Bryan, this will not hurt, but it is simply not neccessary! Or if it was, you could never exchange welded diffs between two trannies (people do that all the time).

It's not about fitting it to a tranny, it's about centering the splines that go thru the spider gear to the exact center of the diff. If you are holding it on your hand you will notice that there is left to right play in the gear itself. If you don't center it with either a jig, or in the case of a tranny than it will bind up and destroy the bearings real quick.

 

[SlowChild3]

How do they drive in the snow?

Sent from my DROIDX using Tapatalk

 

[GRNDSM]

Actually, in the snow, welded center diff would work great! In fact, snow and mud (off road) are the only legit uses for a 4x4 mode that involves turning.

Bryan, I see what you mean, but I never saw a significant enough play to require centering. I did weld a few center diffs "on the bench" and never had a problem. I didn't have a choice, as welder was at my office . Perhaps I just got lucky? Or you got unlicky with an extra worn center diff?

 

[arrowhead]

We call them a 7018 which is the no. on the rod just do it slowly,little bit at a time.

 

[4pistons]

Rick, our disagreement goes back 6 years!

Yes,... we've been wrenching on DSMs for a long time! That's why it was a RESPECTFULL "disagreeance". (I like that word!)

BTW, Speed Design was making their $500, 4 spider center diffs since 97/98. So you didn't have to shell out $1400 for Cusco.

I can't say I remember theirs at the time. But I had already spent over $400 just to replace input/output shafts - TWICE!! I wasn't going through that again! I talked to Dave Buschur, I talked to Extreme, I asked around on all the boards and on the Talon Digest (remeber that?) but no one at the time knew what caused the problem with the splines stripping. I finally realized that it was the side gear thrust washers that were failing. Welding the diff eliminates them so that was my best solution at the time. My motivation was to make a permanent fix, not really to get a cheap 4x4.

To do it right you have to tack it together with the diff

...with the diff and the VC.

The splines should line up with each other when you weld it. If you don't align the splines then you must try to spin the VC by hand to make them line up, which is not easy, but a BIG pipe wrench will do it. Ask me how I know! If you're using a VCE you MUST align them prior to welding as there is no way to make it fit afterwards. It doesn't need to be IN the trans to do it, tho.

Rick - '91 GSX

 

[GRNDSM]

I talked to Dave Buschur, I talked to Extreme, I asked around on all the boards and on the Talon Digest (remeber that?)

Now, here are a couple of handling experts . Actually Buschur has developed quite a taste toward "turning racing", but that didn't happen until more recently.

And I have been a Talon Digest member/contributor since '95 .

 

[bryanwheat]

Yes,... we've been wrenching on DSMs for a long time! That's why it was a RESPECTFULL "disagreeance". (I like that word!)

I can't say I remember theirs at the time. But I had already spent over $400 just to replace input/output shafts - TWICE!! I wasn't going through that again! I talked to Dave Buschur, I talked to Extreme, I asked around on all the boards and on the Talon Digest (remeber that?) but no one at the time knew what caused the problem with the splines stripping. I finally realized that it was the side gear thrust washers that were failing. Welding the diff eliminates them so that was my best solution at the time. My motivation was to make a permanent fix, not really to get a cheap 4x4.

...with the diff and the VC.

The splines should line up with each other when you weld it. If you don't align the splines then you must try to spin the VC by hand to make them line up, which is not easy, but a BIG pipe wrench will do it. Ask me how I know! If you're using a VCE you MUST align them prior to welding as there is no way to make it fit afterwards. It doesn't need to be IN the trans to do it, tho.

Rick - '91 GSX

I wasn't referring to welding the cover and rear output side of the differential when i said that it needs to be tacked in the case. I was referring to the gear in the lower side of the diff. The gear is not a tight fit in the whole because there is no bearing or bushing there. The hole is meant to be bigger so that the parts don't make contact while the transmission is turning. If you don't make a jig to hold it centered or tack it in the case than it will be off center and cause the bearings in the front differential carrier shaft and the lower bearing on the center differential. As for lining up the top shaft with the top of the housing to install a viscous coupler or a eliminator. That is not needed because you don't need a coupler or eliminator. The output shaft doesn't need the ball in place to hold it because the transfer case holds it from sliding out of the splines.

 

[4pistons]

The output shaft doesn't need the ball in place to hold it because the transfer case holds it from sliding out of the splines.

WHOA!! That is SOOOOO wrong! See those worn down output shaft splines??


<img src="http://www.dsmtuners.com/gallery/files/7/9/2/7/failed_shaft1.jpg" alt="Failed Output Shaft" />
That's from the output shaft moving back and forth and filing itself to death inside the xfer case. That ball MUST be retained, whether by non-functioning VC or a VCE, or you'll end up with the same problem. That ball is the only thing keeping the output shaft from moving. It was never meant to 'float' in the transmission.

Rick - '91 GSX

 

[GRNDSM]

The transfer case will hold the shaft in place and prevent it from falling out of the tranny, but that shouldn't be your main concern. I first left out my "shaft keeper ball" back in '96 (didn't know it was there...), the result was a MAJOR tranny fluid leak from the shaft seal! This happened within a week or two of re-assembling the tranny. I am not sure if it moved far enough into the transfer case to cause a physical leak or if it moved back and forth enough to damage the seal (I am thinking the former, because of how sudden the severe the leak was).

It is possible that sometimes you can get away with this if you have a very rusty (thus tight) transfer case splines and they do not allow you move enough to cause the problem. But Rick is right, this is definitely not a good idea!

 

[4pistons]

Now, here are a couple of handling experts.

Yea... not-so-much! But I was asking them about the failed output shaft splines, not handling. See my pic in the post above. That's the SECOND shaft that failed on my car, and no one could tell me what the problem was. I figured if anyone was making output shafts fail it would be their 10 second cars! How could my 13's wreck output shafts and not theirs??

Well it turns out that it was the failed side gear thrust washers in the diff that was causing it. They were allowing the output shaft to move back and forth and filing itself to failure.

Rick - '91 GSX

 

[jakelandry]

I have actually heard of a local guy here who welds the entire gears. He fills each groove in completely and welds them together. Why? I have no clue. He says thats how he always does them. This is being done of v8 trucks however...

 

[lillev23]

I'm looking into welding my center diff, but I have a couple of questions first:

1. I didn't see the baal that would retain the tcase input shaft when I removed the center diff. Any idea where it could have dissapeared to inside the trans?

2. How will I know if my side gear thrust washers are bad?

3. When I seperated the tcase from the trans, tranny fluid came out. Could this possibly be related to the moving tcase input shaft?

 

[turboglenn]

I weldede my spare that had machinig on the inside for an alternate stype of spidergear setup (might have been JDM or something but it was OEM that way and USDMparts wouldn't shimthe spiders), after doing that one and selling it to a friend and taking his as a core and welding it,I know have about 5 of them including my spare that i've done, the other 4 are beat on daily, 3 in 2g cars and 1 in a 1g.. I do it proper with heating pre-weld to 375-400* F, Then either TIG with ER 309 or ARC weld with some 7018 on A/C at about 90 amps

then i depending on how they were heated (in charcoal grill or torch use) i will cool them slowly by either putting it back in the grill till the coals have coooled or i will bury it in my bag of fine media blasting sand to slow the cool after welding (cooling too fast makes the material/metal brittle, cooling slow will only slightly soften it, and soft is better than brittle for obviouse reasons)

No failures on them yet with thembeing driven on the street almost daily (except mine, i can't afford chacing CV stresses or even tires right now) so i keeo mine in case i bust my 2 spider unit

BTW how'd you bust yours? launchign or by shear power pulls in a single gear?