Super diff turning rough

[delsolmanx]

I'm just installing the axles into my swingaxle tranny with a new superdiff and it is turning pretty rough, we put some oil in and it is a bit better bjt you can still feel each tooth as the axle is spun.
With the tubes installed it is a bit worse yet. I've never had superdiff before do they turn a bit stiffer than stock usually?
Spiders are 11 tooth
Side gears are 17 tooth

[[email protected]]

How difficult was the circle clip to get in the diff for the thrust washer? If you literally had to tap it in, you may have added some preload of the side gear on the spiders. You should easily be able to install the snap ring(s), and be able to slide a .005, or so feeler gauge under the thrust washer up against the side gear.

[delsolmanx]

it was a double circlip on each side. Both sides went in fairly easily -- I did not try a feeler guage but I don't think there is any preload on the side gear due to the circlips.
I removed the drivers side side gear and turned other axle by hand and it still was hitting on every tooth by a small amount...

Used side gears with normal wear -- new spiders

do they have a tendency to wear in so they are smooth?

[nsracing]

I hope the 2 addition spider gears are the proper ones that went in. Fine tooth vs. coarse. They cannot mix.

You gotta have the proper spiders for the side end gears you are are using.

And just how much shim did you use before lockup w/ the circlipss?

[[email protected]]

The new spiders may contribute a little to not being perfectly smooth. When you installed the tubes, did you install a drum, and snug down the axle nut? If you just have the axles sticking through the bearing caps of the backing plates, the axle most likely hasn't been seated all the way through the bearing, and is creating pre-load on the side gears. It's not going to be as smooth as a stock worn in 2 spider gear set, but it shouldn't feel notch like, or need any excessive force to turn it.

[delsolmanx]

The spiders are all the same 11 tooth. I have not put the tubes on yet so there is no preload coming from them.
I purchased the tranny from jake raby it was a new build...

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[gears]

Something isn't correct ..
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[delsolmanx]

I had tubes mounted but they bound up on the plastic daisies -- I needed to order more gaskets to shim them out so I removed them.

I have been just turning the axles by hand -- doesn't seem to matter which side I turn versus hold it acts the same way.

Should I try new side gears?

[gears]

Well .. for starters, if the tubes are off and you're turning the axles, one or more fulcrums have almost certainly fallen behind the axle spades. The outer bearings/bearing retainers are what hold the axles from moving too far outward.

Disassemble completely, find out what's wrong internally, reassemble with more care .. and unless you've opened up the oiling on your "Super" dff, it's life is VERY limited.

The paper gasket/shim selection should be determined WITHOUT the axles in place. It's a simple matter to then remove the tubes and do a final assembly with the axles, installing the bearing and bearing retainer immediately, one side at a time.
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[delsolmanx]

Thanks for the reply.

Fulcrum plates were in place, and would not affect the feel of the diff without tubes on.

As stated I did not assemble gear box or diff, just trying to figure out why spiders aren't turning free in side gears...

Thanks for the advice/ info

[gears]

Then it's one of two things:
1) Preloaded spiders - reduce thrust plate thickness to obtain adequate clearance to avoid early failure
2) Diff is machined for 15/10 tooth count - change side & spider gears for proper mesh (this can be checked with prussian blue using ONE side gear only)
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[Stripped66]

Did you "put some oil in it" or did you fill it?

Put the tubes on, install the axle bearing assembly and fill the trans with oil. Then report back.
_________________

[Casting Timmy]

So what is the ideal side gear thrust clearance?

I've been trying to search and seen .010" max, .002-.008".

.005" is mentioned above, which I assume if the ranges above are correct you would want to stay in the middle as a compromise between oiling and gear engagement.

Or is it since we're more likely to burn out with the right wheel, it's more important to shim the left side around .005" or a little higher and then the right side isn't as critical?

[gears]

Trial assembly is the key .. especially when using dual circlips. On the bench, use two HD screwdrivers or small pry bars to press the circlips outward seating them against the outer groove surface. Otherwise, you're NOT getting a true reading.

I usually go for almost the lowest clearance I can with absolutely NO binding. .005" is a good safe clearance, but I've gone as low as .0015". It's rarely going to be the same measurement at all points .. so that low figure is the smallest measurement, with typically a .002" variation.

Super diffs are crude. It's rare that all 4 spiders have equal contact. One spider is usually just along for the ride. So there WILL be break-in during which time this clearance grows. This alone is good reason for an oil change or two in the first 500-1000 street miles. (In fact, I HATE super diffs because they are so crude. For street use, they NEVER last as long as the factory open diff.)

With our GT LSD, .006-.008" is the correct backlash figure .. and because of manufacturing precision, it's the same all the way around. But again, a trial assembly is required (no friction discs installed).
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com