66IISS

So I've been noticing some driveline movement at the past few Milwaukee region SCCA events and I haven't been able to track down what was moving. The motor mounts are solid, the C-beam was tight, the C-Beam mounting holes weren't ovaled at all, the batwing bushings were in good shape, and nothing was loose in the rear was loose. Then, suddenly, the car started "marking it's territory" with a little bit of gear lube out of the rear end. A quick inspection of the seals indicated that I was looking in the wrong place. I should have been looking at the massive crack on the top of the differential housing.

So... I need a new diff housing. It turns out that the Dana 44 HD diff housings don't exist in the used format due to all of the resto-mod guys gobbling them up. I found a source of new housings and even beefed up new housings to the tune of $1100.

So I can get all of the parts I need to do the build but where I'm drawing blanks is who to have build the diff? Shipping the parts elsewhere wont be an issue but it appears that people with C4 Dana 44 diff setup experience don't necessarily exist. I must be in the minority when it comes to breaking C4 diffs, or at least I've got a hidden talent for finding weak parts.

Has anybody got any recommendations on who to send the pile of parts to for a diff build?

Furthermore, has anyone got any suggestions on what parts to add to the pile? The car has had a "stock" diff that was apparently rebuilt in '04 (before we bought it) after it ate a differential at SCCA Nationals. I have no experience in setting up differentials, nor do I know what to look for. I hear OS Giken tossed around a bit but I'm not sure that an OSG diff is worth the $2000 up charge vs. the stock type differential, or at least I haven't heard anyone using them in the C4 that can attest to the positive aspects of the up charge. There appear to be some advantages to the Quaife style regarding maintenance and wear but I'm not sure that makes much sense either? It currently has the stock type clutch differential and the car is very predictable on corner exit (mash the throttle, slide around). The car is used primarily for Autocross in full BSP trim, with the occasional trip to Road America and Blackhawk Farms. It sees street use about once a month in the summer to head to the gas station to fill up and prepare for more merciless beatings.

Time is somewhat of the essence. We have some events in 2 weeks that I need the car ready for. Even though the back up autocross '03 Z06 is fun and equally as fast, there is something about strapping into a loud, obnoxious race car that I don't care to be apart from for too long.

Thanks!
Brad



Cliff notes:
Cracked diff, need a new one. Who in the country knows how to set these things up?

Any major advantages to switching from the stock unit to an OSG or Quaife?

Rob31

There used to be a guy around here . Byrd something . He did a lot of diff rebuilds
White 4th gen firebird in his sig if I remember correctly .Im scketchy on this ....
When is your next Blackhawk trip ?

John B

E-mailed you a solution.

Crepitus

Talk to this guy;

rklessdriver

http://forums.corvetteforum.com/memb...essdriver.html



Seems to know his stuff. I have one of his, works great.

66IISS

@ Rob31 - No clue yet. The car has been sick with various issues most of the year. So far it has seen a new optispark, new injectors, and now a new diff. Once it gets running back to normal I'll have to figure out when my next open weekend is. There are some frequent track days at the Milwaukee Mile on wednesday or thursday nights that I'll likely hit, first.

@ John B - Thanks for the info. I'll let you know what comes of it.







So, any opinions on an OSG or Quaife?

Black89Z51

Zip Corvette out of Richmond VA may have something.

And I agree with Creptius, Will (rklessdriver) is a stand-up guy.

The only other guy I knew that rebuilt them got banned from the forums, permanently. I didn't like his "tone" on the forums so I didn't care for him much, but of the 2 posts I saw him build, I think he knew what he was doing.

Rob31

That's the guy I was thinking of .

Zip Corvettes

We would be happy to help you out. We are a vendor for the HD 44 housing, it is made by Paul Newman's Car Creations and it is very beefy over the stock D44. I do have a used D44 housing but it is not going to be much cheaper since they are about impossible to find and when I do I have to pay through the nose for it. As far as the Quaife, which is the way I would go, you would see allot of benefit in an autocross with it. However it will add allot of money and time to the build because the rear stub axles will require allot of machining and work to get them in. We could try and loosen the rear posi setup a little so the car would not have as much tendancy to fish tail as much under power but it is something we could talk about. Anyways if you need our help I can be reached at
800-962-9632x256
Thanks
Justin

alextz

you have to use a stock case in SP.

alex