Next challenge…the rear end. I’ve got a Ford 9-inch rear (28 spline, not that it matters) that I want to convert to the Chevy 4.75 bolt pattern.

I haven’t priced out yet whether it’ll be cheaper to drill the existing axles and press in studs for the 4.75 pattern or just replace the axles with an aftermarket axle to get the pattern I want. Any input on that part would be appreciated. The existing axles seem to be in great shape.

That said; my main questions are about the drum itself for the Chevy’s and the measurements.
• What years where the 4.75 bolt pattern used? 80’s?...say, a 1985 ½ ton truck?
• Are there any issues with the diameter of the Chevy drum as opposed to the diameter of the 73 mustang drum (10 inch, inside to inside)?
• What are the measurements of the Chevy drums for this bolt pattern?
• Is that the measurement that they are gauged by (inside to inside)? If not what measurement should be taken?
• At 39.00 each for new 1985 Chevy drums, I’m not concerned about cost but, should I consider haven’t the Ford drums drilled to fit the 4.75 pattern? That seems kinda hokey but, maybe that what folks do.

As always, Thanks for the help!
Jon

The cost of re-drill will depend on whether the shop is set up to do this kind of work (has a template, or dividing head setup). The other is which axle you have. Car or truck?. Some need a hole filled to redrill to 4 3/4". I used to have sections of cold rolled bar stock that I filled the holes with.

Chevy drums won't fit the Ford rear housing. Backspacing and center hole are wrong. You will have to redrill the Ford drums also.

Ouch! I was wondering if I'd run into that...
So, it looks like the best way (and cheapest) will be to just have the drums filled/redrilled.
Since this posting earlier, I've totally stipped the rearend down to the tube. No noticable wearage of cracking on any of the gears. That being the case, I'll stick with the axles I have now.

If anyone else has any thoughts, I'm all ears.

Thanks!

When I worked in a machine shop and had access to all the good machines I did this many times....now that I am retired and away from that business and location I use Moser.....

http://www.moserengineering.com/mos...hopservices.htm

They get $80 to plug and re drill....axles and have a quick turn around time...BUT they are in Indiana. There must be a place closer to Texas.....

Man! That exactly what I need. I hope there's someone here in Houston that does it. Surely there is, it's just finding them.

We change bolt circles in axles, drums, rotors wheels etc regularly in my shop.

Yes an indexing spacer is the tool to use on the mill.

We get 65.00 each to do a redrill. Don't need to plug unless the axle is only thick where the studs are now. If the hub is the same thickness all the way around we wiill just locate between existing holes.

Oklahoma is a bit closer than Indiana. LOL

Broken Bow! I know right where that is. I sometimes drive to Poteau, OK for work. I pass right through there.
So, 65 each to drill. How much more to press in the studs (or is that included ).
Now, on to the drums. How much to drill those?
How long would it take? Could I drop them off on the way through on a Monday and pick them up on Wednesday passing back through?

And lastly, any discounts for fellow Hotrodders.com members?

Sure man.

Check your PM's

What wheels are you running or planning on using? Many come in dual bolt patterns, like the Weld Draglites I'm using. I had the same dilemma because my Rambler uses a 5x4.5" pattern like Ford and Mopar, but Jag uses the Chevy 5x4.75" pattern. You can't just redrill Jag IRS hubs either -- they require some machine work because the wheel studs just fit outside a lip on the inner side of the hub. So I just got wheels with dual patterns. I run the same size tire all around too. MY spare is a 5x4.5" pattern, so I'll have to change two tires if I get a flat on the back! Might buy another Draglite for the spare. A narrow wheel with a smallish tire would likely weigh no more than the steel "space saver" spare (from a Jeep Cherokee) I have now.

Not sure. Since I have to replace my Centerline Pro/Truck rims, it's back to the drawing board on that part. I just want to get the same pattern on the back as I now have on the front. No biggie, I'll just have the axles and drums drilled.
Thanks for the info.

3100 I used Moser axles,drilled 4 3/4. bendex 2 1/4 x 11" shoes, and Ford drums drilled to 4 3/4.
you may be able to have your Ford axles drilled.
The center hole in the Ford & Chevy drums are different..With Ford axles you will need to use Ford drums..

Thanks for the feedback.
I ended up having the original axles drilled/threaded and the hubs drilled. We had to thread the new holes in the axles because we couldn't press in new studs. The new holes were too close to the original holes. The metal was a bit thin to add the pressure of pounding in studs.
No biggie. All of the machine work combined cost 110 bucks (cheap) and the new Moroso threaded studs were 33 bucks (kinda high, I thought).
Works like a charm.

I drilled my 9 inch axles to chev bolt pattern [77 bronco 9 inch], but when I tried to put on my 8'corvette ralley wheels, they would not fit over the center of the axle.luckily I had a pair of new aftermarket ralleys that fit the ford axles.I was able to use the stock ralleys on the front, so itworked out ok for me.

I wondered if that might be an issue. To make sure that wouldn't catch me, I picked up some steel chevy rims from a salvage yard. Fit perfect.
I guess the center hole in the Corvette wheel must be slightly smaller...strange.

I own a machine shop in Connecticut. I drill axels often. If the axels are 5 lug now there is no problem. I get $60.00 for 2 axels. If they are 4 lug then you need to plug one hole, there is an additional charge of $10.00 each. Drums are $20.00 each. I don't plug a 4 lug drum. You will have one hole that breaks into the old hole but that isn't a problem.