are super diffs universal or swing and irs specicic?

13del64 · Post by **13del64** » Tue Sep 21, 2004 3:57 am

will a IRS superdiff fit a swing axle tranny also is the question? thanks in advance. Mitchell

Post by **Marc** » Tue Sep 21, 2004 6:01 am

Totally different.

Bruce2 · Post by **Bruce2** » Tue Sep 21, 2004 1:08 pm

Not only that, there are different super diffs depending on what diff gears you have. Early 11 tooth spiders with 17 tooth side gears take a different superdiff than later 10/15 gears.

Post by **Marc** » Tue Sep 21, 2004 1:25 pm

Ooooh, didn't know that (we don't get many 10-tooths down here). Where do you get a SuperDiff for the 10/15 setup? Is that the difference between CBPerformance's #4552 and #4554? (they don't give any details other than the #4554 "racing" unit fits all `61-`68 swingaxles).
Would a SuperDiff be mandatory in a ~175HP/1600lb/slicks drag swingaxle application or would the stock 10/15 stuff be enough? ...I'm in the market if you have some to sell...

Bruce2 · Post by **Bruce2** » Tue Sep 21, 2004 1:50 pm

Marc wrote:Ooooh, didn't know that (we don't get many 10-tooths down here). Where do you get a SuperDiff for the 10/15 setup? Is that the difference between CBPerformance's #4552 and #4554? (they don't give any details other than the #4554 "racing" unit fits all `61-`68 swingaxles).
Would a SuperDiff be mandatory in a ~175HP/1600lb/slicks drag swingaxle application or would the stock 10/15 stuff be enough? ...I'm in the market if you have some to sell...

Marc, the late SSC IRS diffs come with 10/15 gears. Early IRS had 11/17 gears. The same happened to swing axle in 73.
The two CB diffs will both be for 11/17 gears. One has double snap rings, the other is threaded. But if those diffs are exactly as pictured, don't get either. The tiny 1/8" roll pins shear off real easy, then the shafts fall out. I've got the remains of a Berg 5 in my garage right now that was wasted by a diff like the one in that pic (4552). The newer diffs from ERCO have larger 1/4" roll pins. And they use a super thick snap ring instead of two thin ones. ERCO does sell a swing axle superdiff machined specifically for 10/15 gears.
If you want a set of 10/15 swing axle gears, I have a set, magnafluxed.

Post by **Marc** » Tue Sep 21, 2004 2:00 pm

Are the swingaxle 10-tooth spiders interchangeable with late IRS? If not, I guess I'll need four of those if I get the ERCO SuperDiff.
I presume the stock 10/15 swingaxle housing is different than the stock 11/17 unit also? If so, and I decide to risk using the stock setup, I'll need a housing also.
Not in any hurry, project is probably a year away.

Post by **Henryhoehandle** » Tue Sep 21, 2004 2:34 pm

Marc wrote:Are the swingaxle 10-tooth spiders interchangeable with late IRS? If not, I guess I'll need four of those if I get the ERCO SuperDiff.
I presume the stock 10/15 swingaxle housing is different than the stock 11/17 unit also? If so, and I decide to risk using the stock setup, I'll need a housing also.
Not in any hurry, project is probably a year away.

Marc,
Yes, the swing 10 tooth spiders are interchangable between IRS and swing, as is the 11 tooth ones. Weddle sells 10 AND 11 tooth spider superdiffs for either swing or irs. Yes the housings are different and you must use whatever spiders the housing was made for.

Post by **Marc** » Tue Sep 21, 2004 2:53 pm

So I'll need a pair of 15-tooth swingaxle sidegears and either a stock late swing diff or a late swing SuperDiff from ERCO or Weddle, and I can use 10-tooth spiders from late IRS transaxles. Thanks!

Post by **Henryhoehandle** » Tue Sep 21, 2004 6:24 pm

Marc wrote:So I'll need a pair of 15-tooth swingaxle sidegears and either a stock late swing diff or a late swing SuperDiff from ERCO or Weddle, and I can use 10-tooth spiders from late IRS transaxles. Thanks!

Yep... I like to use the 10/15 tooth stuff because it is stronger.

PJMS · Post by **PJMS** » Tue Sep 21, 2004 7:04 pm

Henryhoehandle wrote:....Yes the housings are different and you must use whatever spiders the housing was made for.

I don't think the housings are different. I believe they are the same for swing axle from 67 onwards, no matter if you use 11 or 10 tooth spiders.

_INDY_ · Post by **_INDY_** » Tue Sep 21, 2004 7:12 pm

WHOA! somone finally told marc somthing he didn't know

Bruce2 · Post by **Bruce2** » Tue Sep 21, 2004 8:37 pm

The superdiff housings are different for 11/17 vs. 10/15 gears. But if you have a stock diff housing, they are all the same for both gear sets. IRS and Swing.
The difference lies in the angle of the second spider gear axle relative to the first. In order for the gear teeth to properly mesh, you have to alter the angle of the second pair of spiders off 90º. And this off angle is different between 11 tooth spiders and 10 tooth gears.

Post by **Marc** » Wed Sep 22, 2004 6:03 am

That makes perfect sense. I couldn't visualize why the stock housings would need to be different, now I know they don't. I've only seen one 10/15 swingaxle (a factory exchange box), wasn't able to take that one apart to check interchangeability.

Post by **Henryhoehandle** » Wed Sep 22, 2004 12:44 pm

PJMS wrote:
Henryhoehandle wrote:....Yes the housings are different and you must use whatever spiders the housing was made for.
I don't think the housings are different. I believe they are the same for swing axle from 67 onwards, no matter if you use 11 or 10 tooth spiders.

Bruce clarified this... stock diffs are the same and superdiffs are different