Drivetrain Mustang II 5 stud rear axle conversion

Nordic Cowboy · Oct 28, 2023

Has anyone replaced the stock 4 stud rear axles with 5 stud ones? I have a 65 8" rear end but by my measurements, it is about .250 inches longer than the II's. I've read that
the 65 will bolt up but it seems the spring perches would have to be moved and I am concerned what this may do to the wheel offset. The goal ist to replace the 13 " wheels with 16" ones.

2Blue2 · Oct 28, 2023

Very little bolts right in
I think on the 90-92 Ranger you have to get the v6 and not I4 rear.
think custom axles might be your best bet, you can have 31 spine in a 8 inch with the right mods.

extra_stout · Oct 29, 2023

If you have a 8inch rear end in your Mustang II, you can just swap the axle shafts from the 66 Mustang axle. they will fit. You need to swap the rear axle retainer. To do so, you need to remove the wheel bearings, so it's the best time to replace the wheel bearings (and the locking ring!).

extra_stout · Oct 29, 2023

Here is a thread about custom made axles:

Drivetrain - Ordering New Axles

If anyone needs any info, I'm ordering new Moser axles for my II, since after the last time at the track, I'm gonna have to go through some tough tech inspections for the first few races... So I thought I would pass this info along if anyone needs it! Matt

stangnet.com

Or you can let some one redrill the pattern of the stock axle. This needs welding of the old holes, but there are companys who will do that.

welder4956 · Oct 29, 2023

Nordic Cowboy said:
Has anyone replaced the stock 4 stud rear axles with 5 stud ones? I have a 65 8" rear end but by my measurements, it is about .250 inches longer than the II's. I've read that
the 65 will bolt up but it seems the spring perches would have to be moved and I am concerned what this may do to the wheel offset. The goal ist to replace the 13 " wheels with 16" ones.

The 65 rear end will fit without moving the spring perches. The difference is only 1/8" on each side and the leaf springs bushings and spring perches will easily accommodate the difference. If you are not comfortable with the alignment, just slot the holes in the spring perches 1/8" on each side to allow the leaf spring pins to drop straight in.

welder4956 · Oct 29, 2023

extra_stout said:
If you have a 8inch rear end in your Mustang II, you can just swap the axle shafts from the 66 Mustang axle. they will fit. You need to swap the rear axle retainer. To do so, you need to remove the wheel bearings, so it's the best time to replace the wheel bearings (and the locking ring!).

I have done this swap using new Yukon axles and the 65-66 axles will fit, but it is not a straight swap. A spacer is needed between the bearing and shoulder to make the axle flange line up with the face of the brake drums. Otherwise the axle does not stick out far enough on each side. Might be OK with a rear disk brake swap, but I have not tried it. Seems like I had to machine the axle diameter smaller to use the Mustang II axle bearings. Not sure if the 65-66 bearings will fit inside the bearing cups on the MII housing. I'll be swapping the gears out later this week unless we go out of town, so I'll get some photos and dimensions for you.

Edit: The axle bearing dimensions are the same for 66 and 76. This may have been an issue with using the aftermarket Yukon axles. I's only been about 20 years since I did the swap.

Nordic Cowboy · Nov 1, 2023

Wow folks,
Thank you for all the great advice. I really appreciate the spec sheets. You have removed much of the mystery. I am considering re-drilling the stud plates . That will give me a chance to compare the axle bearing diameter, distance from the hub, and length to the 65's.
I am very curious about dropping in the 65 rear end but that will require a gearset. Not sure what ratio to select with out overdrive. Stock is 3:18 and I assume that is pretty close to what I should run but they matched that to 13" wheels . I have a new Performance Automatic C-4 and don't want to subject it to high rpms at cruising speeds. Has anyone tried the Gear Vendors tail shaft mod which gives a hi/lo for each gear?

Drivetrain Mustang II 5 stud rear axle conversion

Nordic Cowboy

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2Blue2

will be trying this sex one when I can find it

extra_stout

extra_stout

Drivetrain - Ordering New Axles

welder4956

welder4956

Nordic Cowboy

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Drivetrain Mustang II 5 stud rear axle conversion

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will be trying this sex one when I can find it

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