Considering rear end change

65fastbackresto · Jan 4, 2008

Wondering if anyone has any vendors they could recommend for this, looking for a solid 8 inch or 9 inch with posi track, maybe 355 gears, I`m geussing there though.

Dont want any salvage yard stuff either.

68conv4sp · Jan 4, 2008

resto, I just bought and installed an 8 inch 3rd member w/ the later, stronger waffle pattern with 3.55s from Ironhorse 1968 on Ebay. It was about 7 bills delivered from Indiana to Ca, and runs smooth and quiet. Really woke up my stock 289.

65fastbackresto · Jan 4, 2008

To be honest the guts of the rear scare me

I mean ALOT. I`ve watched alot of shoes on TV where they are setting backlash and all kinds of crap that I honestly have no idea how to do. I dont know ANYTHING about the things either, I know I want a posi track, or at the least be able to burn both tires instead of 2.

I`m totally lost on this issue, but I think I could bolt a new rearend on and even get the pinion angle right, thats kinda where I`m at right now anyway.

I`m very intimadated by this part of the job, cause there are a whole bunch of ways to do this wrong, and only one way to do it right.

Some dude told me last year that a shop would probably want like $1000 just to rebuild a rear, and I`m thinking a new one would cost $2000 maybe? Somebody correct me if I`m wrong, which I prob am.

65fastbackresto · Jan 4, 2008

Ok, need advice

I`m looking at Currie-Built crate rearend so I can get something to compare too. But I dont know the difference in these things.

Traction lock

TrueTrac

Detroit Locker

They also have a "9 Plus Sportsman Nod Gear Case and big bearing pin setup....which obviously tells me NOTHING about it, cept it costs a little more.

They got more stuff, but I think these are the only options I would consider. I need advise guys, whats the difference in these rear ends and which one do I need. Its just a street car with a hot little 302 in it, currently with C-4 but gonna do a T-5 conversion this spring.

68conv4sp · Jan 4, 2008

My mechanical skills are limited but I'm glad I did it myself, with only one exception. Lying on my back under the jacked up car (w/ jack stands) leaves a small area to wrestle with the 90lb. chunk. It almost tore my hand off at one point. Use a jack to raise the 3rd member into place (learned the hard way). The rebuilt diff w/ 3.55 and 4 pinion limited slip cost 700 shipped (Ebay - Ironhorse1968). The job took me 4 hours going slowly and using an impact gun when possible to speed things up a little. Also plan on changing the axle bearings/grease seals on the outboard ends of the drive shafts. The machine shop pressed the old ones off and installed the new ones for $75. This project is fresh in my mind so ask anything.

68conv4sp · Jan 4, 2008

My guess is that you have an 8 inch rear end, but you need to confirm that unless you are considering changing out the entire axle. Going to a T5 (I just installed a TKO500 - similar) does not require that you go to a 9 inch rear end. If you plan on building a torque monster, you should go to the 9 inch now, rather than build up the 8 inch. But for most 302 and smaller, I think most people would agree that a well built 8 inch is sufficient.

65fastbackresto · Jan 4, 2008

I wont really know the right questions

to ask till I get my hands dirty if you know what I mean.

I do know this, my 8 inch rear is junk, it clunks and makes noise. Plus I may try and rebuild it later for use on another mustang.

jcode68 · Jan 4, 2008

65fastbackresto said:
I mean ALOT. I`ve watched alot of shoes on TV where they are setting backlash and all kinds of crap that I honestly have no idea how to do. I dont know ANYTHING about the things either, I know I want a posi track, or at the least be able to burn both tires instead of 2.

The good news here is you can buy the 3rd member with the gears already installed on the chunk as 68conv4spd did. Setting the pinion gear depth and gear backlash etc is done when installing the gear set to the chunk. When you buy these completed, all you need to do is pull the axles, remove the old chunk, install the new and install the axles. As noted, would be the right time to replace axle bearings and seals also, but that is simple as well. My advice (and what I plan to do shortly) is to replace the chuck with some type of posi/trac loc rear chunk for my 8" rear. I did the T5 swap last year and am planning on using 3.73:1 gear set. Should work well with my combo.

65fastbackresto · Jan 4, 2008

If my gear set is an open diff

I can just change the chunk and have a posi? the cases aren`t diferent?

This wouldn`t scare me as bad if I dont have to mess with the backlash and stuff.

geostang351 · Jan 4, 2008

65fastbackresto said:
I can just change the chunk and have a posi? the cases aren`t diferent?

This wouldn`t scare me as bad if I dont have to mess with the backlash and stuff.

Correct!

65fastbackresto · Jan 4, 2008

I`ll get the tag info off the rear

this weekend, so yall will know for sure what I have before I proceed, I`ve already wasted some money here and there that I shouldn`t have by being impatient. Will the tag indicate how many splines I have on my axles? Or is that even an issue?

CraigMBA · Jan 4, 2008

If you have an 8" they are 28.

It's a pretty easy swap, abiet a little messy. I hate gear oil.

65fastbackresto · Jan 4, 2008

I`m gonna take the rear end out to do it

Its pretty easy, I had it hanging when i replaced the leaf springs, so every bolt it takes to drop it has been off recently, and with it out of there, it`ll give me a chance to detail some of the harder to reach areas under the car and on the rear.

Yall about have me talked into trying this, but none ever explained the difference between these.

Traction lock

TrueTrac

Detroit Locker

mtbdoc · Jan 5, 2008

The true trac looks to be a good compromise. I really don't think most folks want a Locker on the street (although there have been MANY discussions about that on various high performance auto boards). I have an 800hp blown 408 going in a 66 vert (link in sig below) and will use a True Trac.

Traction lock is a clutch-type setup, with more maintenance/wear issues. The True Trac has a really interesting engagement system. Here is a link to Eaton's website" http://www.eaton.com/EatonCom/Produ...ducts/Differentials/DetroitTruetrac/CT_126339

As far as my car, we are actually getting ready to move forward. The D2 blower is intruding into the fender area in front of the driver's side tire, and I am struggling to get the information on this blower as it is older. Procharger has been helpful. I too will be ordering my rearend 'pumpkin' soon if all goes well.

65fastbackresto · Jan 8, 2008

Need more input on this rear end swap.

68conv4sp said:
My mechanical skills are limited but I'm glad I did it myself, with only one exception. Lying on my back under the jacked up car (w/ jack stands) leaves a small area to wrestle with the 90lb. chunk. It almost tore my hand off at one point. Use a jack to raise the 3rd member into place (learned the hard way). The rebuilt diff w/ 3.55 and 4 pinion limited slip cost 700 shipped (Ebay - Ironhorse1968). The job took me 4 hours going slowly and using an impact gun when possible to speed things up a little. Also plan on changing the axle bearings/grease seals on the outboard ends of the drive shafts. The machine shop pressed the old ones off and installed the new ones for $75. This project is fresh in my mind so ask anything.

This and a bunch of the other posts have me talked into trying this. I want to be sure I dont have to mess with backlash or anything really funky doing this, any more input would be appreciated. I am gonna totally remove the rear end from the car to do this, one reason is so I can clean it up and detail it.

Anyone know anything about the waffle pattern, or if thats a good deal for $700?

68conv4sp · Jan 8, 2008

resto, I beleive the *waffle pattern* strengthening ribs were added to the 3rd member as a result of some failures of the earlier (65, 66), non-ribbed unit. Most of the sellers on E-Bay who seel the units already set up with posi and your choice of gears use the stronger ribbed pattern anyway.

As for removing the whole axle, I understand that you are doing it for detailing reasons. Without doing so, the job took me about 4 hours.

truck90278 · Jan 8, 2008

Suggest you follow up with Currie. We're using a Curie center section with True-Trac and 3.55 gears. They also can use a stronger center section (better ribbing) than what is in your present differential. Assuming your not outrageous with HP, an 8" is fine and can take a lot of abuse. WE're running a 347 backed up with an AOD. Makes a nice combination

geostang351 · Jan 9, 2008

truck90278 said:
Suggest you follow up with Currie. We're using a Curie center section with True-Trac and 3.55 gears. They also can use a stronger center section (better ribbing) than what is in your present differential. Assuming your not outrageous with HP, an 8" is fine and can take a lot of abuse. WE're running a 347 backed up with an AOD. Makes a nice combination

Truck,
What size center section are you using? How much is the cost from Currie?

Thanks

70vert · Jan 9, 2008

+1 on the TrueTrac. That's the style I plan to go with, the torque-sensing or torque-biasing. If you really want to splurge, you might consider a Torsen T2 or T2R, or even a Black Gold diff, 1/4 tight. Spendy though - if you're not producing a ton of power I'm sure the TrueTrac will be fine, but here's a link to some comparisons of Truetrac vs. Torsen - Torsen was the first, IIRC, and Truetrac is a cheaper copy:

http://www.google.com/search?q=truetrac%20vs.%20torsen

truck90278 · Jan 9, 2008

geostang351 said:
Truck,
What size center section are you using? How much is the cost from Currie?

Thanks

It was ~$1,200 complete with all new components. They aren't the cheapest, but they are dependable and back their product.

Considering rear end change

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