Well, I noticed last week that my rear end was catching. Whenever I would go around corners it would catch and make the loud "pop". Talking to our friend, and after taking him for a ride, it's the spider gears in the rear end. Our friend is a very experienced mechanic and can replace the spider gears, but the only problem - where do we get the spider gears?

The problem is that we do not have a stock rear end. It is an 8 bolt, traction lock rear end (with four lug wheels, which is really strange) and it has no tag identifying what it is. Where do we start?

 

If you are describing the original 7" differential, it's an Equalock, not Traction-Lok. 66 was the last year for the 7" limited slip diff. Almost no parts are available for the 7" diff, almost certainly the clutch plates, gears, etc. You can get the bearings and seals, and that's about it.

However, what you describe might also be lack of friction modifier, M-19546-A. Lack of this causes the clutch plates to "stick", causing symptoms exactly as you describe. Add a bottle of that. If it doesn't work, you're out $10. If it works, you're done.

 

Okay, I've talked to him and he'll try adding some friction modifier. If this doesn't work, I take it we're in the market of looking for a new rear end? What all will fit?

 

A bolt in would be 64-66 mustang/falcon that is a inline 6 or you could upgrade to a 8 inch but those are 5 lug so you would have to change rims in the back.

 

Yeah I was thinking about that last night as I went to sleep - new rims in the back.

Other than that, what would it take to upgrade to an 8 inch? I assume a modified driveshaft. What else?

 

Or you could just install a used 7". Bolt-in, no change in configuration, no wheel change, etc. Save a lot of money.

 

Yeah I hear you there too. I mean I see pros and cons to upgrading and staying stock, but money would definitely play a factor in keeping the 7 inch setup and I'm leaning that way. I posted a "wanted" ad in the "want to buy forum". I'll do some junkyard hunting this weekend. If anyone has one laying around, private message me.

 

Well, a local shop here can provide one, no doubt, but hopefully you'll find one closer to home. They came in two flavors- 2.80:1 (auto) and 3.25:1 (manual). The pinion yoke was different, typically the smaller one on manual, although the early auto had it, too. They can be swapped, if necessary. Oh, there was an optional 3.50:1 axle 64-66, but I have seen exactly one, ever.

 

What will it take to swap yokes?

A local shop is selling a rear end out of a '65 three speed. Will this work?

 

That's almost certainly an open 3.25. Good choice.

Swapping the pinion yoke and seal is quick and easy. Takes under 2 hours. Cost you a seal and a nut.

Too easy.

Remove the drive shaft.
Remove the pinion nut.
Remove the pinion flange, clean seal surface.
Remove the seal.
Clean seal bore and pinion shaft threads.
Install new seal.
Lubricate seal surface of pinion flange with gear oil, and install.
Install a new pinion flange nut, and torque to 125 ft-lbs.
Install the drive shaft.

You can easily make a tool to hold the pinion flange while removing or installing the pinion flange, but even a large pipe wrench will do.

This trick eliminates the need for a new crush collar, which is especially good news for 6 cyl owners, since the 7" collar is not available anywhere. The 125 torque is far less than the 175 spec, so it does not further compress the collar. Using a new nut assures the accuracy and reliability of the 125 torque.