I bought a set of Dana 60 strange aluminum main caps and they need to machined to fit. I got them machined to the right spec on the bore but it seems the edge of the new cap and the edge of the case dont line up just perfect. I put the factory caps on an it seemed to fit the same way. Anyone ever seen this be for?

Are you talking about the inside surface for the race not lining up? Could you have the caps upside down?

There is absolutely no way in the world that I would suggest, let alone use, alumunim caps on a drag race rear end Billet steel, YES

[/quote] There is absolutely no way in the world that I would suggest, let alone use, alumunim caps on a drag race rear end Billet steel, YES [/quote]
I would Second that !!!

I've had Strange caps in my Dana since the 80's. Has run high 9's. Planning on running mid 8's.

This is what I bought. They say they are much stronger then the factory steel cap. Yes it doesn't line up just perfect where the race sits inside. It's not way off but it not a perfect fit. I got them machined down to the spec that strange calls for on the bore diameter.

I called Strange and they say they are far superior to the factory caps. I also got a cover with the load bolts so that should also help.

The Dana 60 in my Cuda has dual Mark Williams steel caps and 40 spline M.W. aluminum spool and axles, it had a set of Pro 5.86 gears in it when I bought and a LPW aluminum cover with the load bolts in it as a roller. I changed the gears and spool to a set of 4.56 with a Strange Engr. steel spool This car has reportily ran 7.60 at 184+ MPH weighing 2500 lbs with the driver and a KB aluminum B1 motor with a blower running methanol, all the rear end parts look excellent
I figure that no one would make or sell aluminum caps for a rear end in anything other than sport car or extreme high speed racing where there is very little shock to the drive train

Ideally you would like to machine the caps attached to the housing. The bolt holes are off some. This holds the cap in a off center position. Open them slightly and the race should center the cap.
Doug

Tom's Differential has steel caps for $90.00 with attaching bolts.

http://www.tomsdifferentials.com/2011catalog/Pages96-100.pdf

Just saying....

strange alum/caps 17 years 8.87/155 mph

I already bought the strange caps and fitted them to the case. Not sure how you would machine the caps attached to the housing.

Line bore, that's how. Probably impractical.

The cap needs to line up.

The last set fo Mark Willaims steel caps I put on one of my 8 3/4 rear ends had a specific inside diameter, +.0010. I took the third member and the new cap to a local machine shop and they let me fit them on my own using thier Sunnen rod machine to surface the new caps to get that dimension set up corectly. I took my own inside and outside mikes along to do the measuring I ended up being within .0002 from the max I.D. at room temps

Can this be line bored?

The caps are oversized and have to be machined off of the mating surfaces.

No you can't line bore this application, NOR would line boring them achieve what you're trying to do. Nor can you machine them with the caps on the case...... Way wrong.

To the OP: I'm working with an 8-3/4", not a Dana, But my factory caps were as I believe you are describing. The mating surfaces, and the threads fit and aligned, but the edges of the caps hung over the edge of the case mating surface and were nowhere near looking like a matched set. The MW steel cap I installed on mine actually fit the case much better, but still not perfect.

Is this what you're describing? If so, I think its inconsequential. What's important is the that the bore is correct, and that the threads align when the cap is centered on the bolt/hardware. I'd say move along, you're fine.

You wouldn't want to. Especially with the axles tunes in housing.

I was sort of being sarcastic. Dana bored the bearing race fit when new.

You machine the thick cap down till the bore is correct. Now you have misalignment at the parting line. Is it the cap or the bolt holes to bore in the housing to blame?

Post a pic and someone can tell you what's wrong or how to correct.