Decided to build an 8.5 10 bolt...Couple questions to the diff guru's

[67CamNKC]

I'm pretty pumped, got the bottom of the car POR15'd and undercoated this past weekend. It's coming off the rotisserie soon! (took longer than I imagined)

The car I bought had an 8.5 in it, so I'm going to use it.

If I'm starting with a bare housing..........Whats better Tru trac or Eaton? This will be a full time driver/ part time autocross car.

Anyone offer a good deal on these and bearing kits? Jegs seems ok, but I'm looking.

If I upgrade to 30 spline, all the carriers say they need special bearings. Are these readily available?

Lastly, I was looking at installing rear ls1 or lt1 brakes on this housing. Do they require an adapter? I can ask over in the brake forum, if needed.

[Randy67]

The ls1/lt1 brakes bolt right up. You can't go wrong with the Eaton clutch style, but the trutrac is pretty good as well. I have autocrossed both and they both work equally well.

[67CamNKC]

Thanks Randy. Anyone know anything on the bearings?

[Rhino]

Lastly, I was looking at installing rear ls1 or lt1 brakes on this housing. Do they require an adapter? I can ask over in the brake forum, if needed.

Unfortunately I don't know about the bearings, but as far as brakes are concerned, the backing plate will bolt right up. When you order axles, make sure to order them with the correct brake offset. I'll have to go back to my order to determine exactly what that is. When I ordered everything from Moser, I just told them the brakes I was using and they cut the axles to match. This may just be an issue since I'm using a 12 bolt, but figured I'd mention it to be on the safe side.

[67CamNKC]

Dang, I read in another thread that I could use the $250 Moser 30 spline axles in the upgrade..........If not, I may have to space out the backing plates?

[Rhino]

It looks like the rear brake offset is 2.77" for the LS1 rear brakes. https://www.pro-touring.com/showthread.php?72054-LS1-Rear-Brake-Dimensions
I think I may have had an issue with it since I'm using the ford big bearing ends on my 12 bolt. I believe the stock brake offset for the Ford 9" is 2.5"

From everything I'm reading the offset should be 2.75" for your 8.5" 10 bolt, which would make it a non issue. You may want to verify with them before ordering.


The 2.41" measurement is the overall height of the rotor from the outside of the hat (the wheel mounting surface) to the far friction surface. The Brake Offset Dimension for the 98-02 F-body housing is 2.77" IIRC.

HTH,
Tobin
KORE3

[big gear head]

The best installation kits that I have found are DTS, Tom's Differentials, Dewco and Yukon. I have been using the Yukon kits for several years now. The Yukon kit has 2 crush spacers in case you mess up the first time. These kits come with the correct bearings for the Eaton and Truetrac differenials as long as you order the kit for that differential. The bearings are easy to get as long as you know which bearings you need. I keep 2 sets on the shelf all the time.

The Moser axles are also no problem. I've used more of them that I can count. Again, you need to order them correctly.

I usually recommend the Truetrac or Torsen for auto cross and road racing. These just seem to operate smoother than the clutch type differentials, which will help the tires keep their grip in a corner.

[67CamNKC]

Good info! I yanked the axles out tonight and have some concerns on my rearend. It appears to have had aftermarket spring perches welded on. Welds look good, but perches look like the add on type. Maybe this rearend isn't out of a nova. Can someone help me identify the diff? Here are the measurements and markings.

It roughly measures 55-1/2" from backing plate flange to backing plate flange. Pulled the axles and they measured the same at 30-3/16" overall length from wheel mounting surface to the end of the shaft or 29-11/16 from WMS to the front edge of the c-clip groove. WMS to pinion centers are roughly 28.5" and 27". I found an 087 on one side of the pumpkin and on the other side there was an 12345 on the top and a 67890 on the bottom. From all the pictures showing the differences in 10 bolts, the square bottom notches show this to be an 8.5.

I just want to make sure this something I want to put my money in......

[Rhino]

From all the pictures showing the differences in 10 bolts, the square bottom notches show this to be an 8.5.


If it looks like a 8.5, you can be pretty certain that it's what you're looking for. I do believe that BOP had a rear end that externally looked like a 8.5, but had much weaker guts. From what I hear those are rather rare.

This is the best resource I've found for identification. http://www.novaresource.org/axle.htm

[67CamNKC]

Well, the axle code I found of GZ G 3482 somewhat fits the '71 and later layout, but my codes aren't listed. Maybe it's been narrowed and wasn't out of a nova?

EDIT: I found a casting number of N 1235542 and GM 1. The pinion nut is 1-1/4". I'll look on google......

[67CamNKC]

Ok looks like the N 1235542 is a real common casting in 73-75 novas and camaros. Dimensions aren't matching up so I may have a modified rearend that I don't want. Axles look like stock units so not sure whats up.

[Rhino]

If they look like stock axles I would bet the width hasn't been modified at all. If I was to put money on it, I'd say it was a 2nd gen F-body housing.
I think the 2nd gen rear end was 55.25" flange to flange. An axle for that housing would be pretty close to 30". Assuming it is a 2nd gen rear, the spring seats would have been a little too wide and have to have been moved inward.

[DarkoNova]

When I blew my 8.2" rear end, I found an 8.5" 10 bolt out of a later model Nova. I forget the exact year, but I think anything from 72-79 basically had the 8.5" as the "base" rear end. Mine measured 54.5" from backing plate to backing plate, and I think the axles were exactly 30", but I could be wrong. I know the whole housing was 54.5" though. you might have an axle out of a Camaro. Supposedly the rear quarters on Camaros were wider than Novas.

[big gear head]

If it has axles that are 30 1/8 inches long then it's a '71 to '81 Camaro or Firebird rear end. The Nova axles are 29 5/8 inches.