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View Full Version : Differentials- How was your decisions in the long run?



T1Bird
10-12-2008, 09:12 PM
I'm currently trying to make a decision here, I rebuilt my rear end 2 years ago with the cobra clutch packs and upgraded S spring, I had them setup the stock method, I think S-C-S-C etc. Over the past few drag strip days Ive noticed my 60fts going down as the day wears on, and people telling me my left wheel is not spinning in the burnout. I'm stuck on if I should rebuild the clutch packs again with new cobra clutch packs in the alternate method, which I dont know what it is, or put the Auburn pro in the car. The reason Im putting this out there is there is always posts on what to get, but Im looking for answers on people who have got the Auburn pro or the alternate clutch pack rebuild, how are thier thoughts over time and dragstrip use on thier decision.

I partly have a Auburn pro on order, but the guy who ordered it for me, said that he feels the cobra clutch packs are a better system as you can just rebuild the clutch packs when it wears out, where as the Auburn you have to replace the whole unit, so 100 vs around 550 say. How have the Auburns held up over time and abuse for those that have it.

Thanks for your help in advance.

Bruce

XR7 Dave
10-13-2008, 08:44 AM
Auburn offers a rebuilding service.

But you probably won't need rebuilding. My Auburn started life in Dennis Dimitratos' car back in - maybe 1999? It lasted quite a few years and over 50K miles in our XR7. It now resides in Mike Irving's car. I think it still works fine....

SCrazy
10-13-2008, 09:53 AM
I've got the Auburn in my car as well with no issues what so ever.

David Neibert
10-14-2008, 11:02 AM
Bruce,

I've got the Auburn Pro in my turbo car and a stock rebuilt trac loc in my 91. Both feel the same to me. Before going with the Auburn, I'd rebuild what you have using the alternative stacking method and the F-150 S spring. I helped Kurt K. do this on his SC and it was pretty easy except for stuffing that S spring into place.

David

Kurt K
10-14-2008, 11:12 AM
I've been happy with the alternate stacking method w/ F-150 S-spring in my traction-loc for the several years it's been in there.

XR7 Dave
10-14-2008, 11:42 AM
I've been happy with the alternate stacking method w/ F-150 S-spring in my traction-loc for the several years it's been in there.Sure, its easy to say that when the last several years you haven't had a tranny for more than a week good enough to even do a burnout. :p

Roadhawg
10-14-2008, 11:50 AM
it was pretty easy except for stuffing that S spring into place.

David

Makes me chuckle........I thought I was the only one that had F150 spring issues.

It is sort of like trying to stuff 20 pounds of crap into a 5 pound sack.

racecougar
10-14-2008, 09:15 PM
I've been happy with the alternate stacking method w/ F-150 S-spring in my traction-loc for the several years it's been in there.

Ditto.

I have the alternate stacking method w/F-150 S-spring in my XR7, and the regular junk in my LX. Both get the job done, but the trac-loc in the XR7 has noticably better/sooner/stronger engagement. I can't give you any comparison to an Auburn though, as I haven't tried one.

Kurt K
10-15-2008, 01:26 AM
Sure, its easy to say that when the last several years you haven't had a tranny for more than a week good enough to even do a burnout. :p
Ouch, that hurts. However, I was told that tonight that it looks like I will need to rebuild my traction lock or go another route :rolleyes:

T1Bird
10-15-2008, 01:15 PM
After alot of research Ive decided to go with the Auburn pro, I think with a proper rebuild of the trak lok I could get by, but build it big or go home I say.

One of the main reasons I have decided this is because this has been brought to my attention and it makes sense to me, If I were building my car for straight everyday abuse Id put the heavier S spring in again, like I have now, but for a car thats driven on the street and cornering, the heavier S spring only wears clutchs out faster. Ill copy and paste what was said to me.

With regard to your rear-end, here is my take on it. You wore out the clutches because of that stupid F-150 'S' spring. This spring is a pre-load spring, meaning that it's only function is to start the side gear loading. More on this in a minute.

When you are just cruising around turning corners, that spring causes the clutch packs to resist slipping when the differential is doing it's job: allowing the outside wheel to rotate faster because it has farther to travel. The beefier the spring, the more resistance there is to differential action, and the greater the wear over time.

OK, now back to side-gear loading. Consider how our differentials operate; the ring gear turns the carrier with two spider gears on a shaft and these gears mesh with the side gears to drive the half-shafts. The teeth of these gears are angled, so when force is applied these spider/side gears try to force themselves apart (teeth want to ride out of the mesh). THIS is where all the power to engage the clutchpacks comes from, NOT the pre-load spring.

Now, the spider gears in the carrier cannot move outward at all, but the side gears can (and do) slide outward on the splined half-shafts. This puts great pressure on the clutchpacks, which is what gives you the "limited-slip" action. The one problem with this type of design is that you must have a small amout of side thrust on the side gears in order to start the loading process: introduce the pre-load spring!

My advice to you is to re-build your current set-up and use the C-P-C-P-C-P sequence (C-clutch, P-plate), stuff as many as you can in there (I think mine took 6 stacks/side IIRC), and ditch the stiffer pre-load spring.

Bruce