[rand68]

I have a 68 GTO with an 8.2" 10-bolt standard differential rear-end.

How much work would be involved to upgrade this rear-end to some sort of limited-slip? Several of the repro parts places have posi or semi-locking differential units for sale for fairly reasonable prices.

Is new the way to go or should I go junkyarding? Should I just find a whole new rear-end?

What's the best option? (With money being an important factor. I can't afford $1500 for a custom setup)

Thanks!

[rand68]

I have a 68 GTO with an 8.2" 10-bolt standard differential rear-end.

How much work would be involved to upgrade this rear-end to some sort of limited-slip? Several of the repro parts places have posi or semi-locking differential units for sale for fairly reasonable prices.

Is new the way to go or should I go junkyarding? Should I just find a whole new rear-end?

What's the best option? (With money being an important factor. I can't afford $1500 for a custom setup)

Thanks!

[goatseeker]

Rand,
I'm watching your post for responses too as I'm looking to do the same on my '66.
I think I've read here that Pontiac, Olds and Buick rear ends are interchangeable. If so, this would greatly expand the potential junkyard inventory you could pick from.
Pontiac Enthusiast magazine is supposed to have a tech article in the next issue (Oct/Nov) on upgrading GTO open diffs to posi. This should provide some insight. I'd like to keep the original rear end in my car but if it's too costly or too much of a PIA I would consider swapping too.
I'll keep an eye out for info on this.

[rand68]

Apparently no one reads this forum. I'm sure Ole Pinion Head knows the answer but apparently doesn't frequent this board.

I think I'll repost over in Drivetrains. [img]smile.gif[/img]

['ol Pinion head]

New Auburn cone-type posi carriers are avail for 8.2 10 bolt Pontiac rears with low ratio (3.36, 3.55, 3.90, etc) gears. About 14 months ago an Auburn mid ratio (2.93-3.08-3.23) carrier was introduced as well. Do not know if it was a one shot deal or not. Randy's did quit carrying these new mid ratio Auburns according to my price sheets. Have heard rumours that Eaton was working on a clutch type 8.2 Pontiac carrier as well. On many 8.2 builds, I use #1 condition reclaimed 4 pinion Safe-T-Track carriers. Have also used over a dozen of the low ratio Auburns, all have gone in cruisers & a few in high point showcars.

To install different carrier, looking at installing new carrier bearings & then re-establishing backlash with asst of side shims. If pinion is loose, rearend will need to be set up by a pro.

[rand68]

Originally posted by ol' Pinion head:
New Auburn cone-type posi carriers are avail for 8.2 10 bolt Pontiac rears with low ratio (3.36, 3.55, 3.90, etc) gears. About 14 months ago an Auburn mid ratio (2.93-3.08-3.23) carrier was introduced as well. Do not know if it was a one shot deal or not. Randy's did quit carrying these new mid ratio Auburns according to my price sheets. Have heard rumours that Eaton was working on a clutch type 8.2 Pontiac carrier as well. On many 8.2 builds, I use #1 condition reclaimed 4 pinion Safe-T-Track carriers. Have also used over a dozen of the low ratio Auburns, all have gone in cruisers & a few in high point showcars.

<font size="2" face="Verdana, Helvetica, sans-serif">Thanks for answering OPH.

Ok, now bear with me. If I understand correctly the "carrier" is what your ring gear attaches to. So you're saying that I can buy a new carrier, slap it in (so to speak) and it replaces the differential gears with a limited-slip setup. From what I read in my newly-delivered shop manual there are 3 sizes of carrier, so I'd need a medium sized carrier to re-use my 3.08 gearing.

Would in your opinion I be better off buying the larger carrier and going with the 3.23 gears? This car is strictly for street and highway cruising. It's got a TH400 transmission. My projected hp is in the 350 range with projected torque around 420. I'm just asking because if I go with the medium carrier I'm basically locked into no higher than 3.08 gears unless I replace the whole carrier (not a cheap option). I don't know that I would want higher gears (especially with gas prices the way they are) but if I ever went to sell the carrier I think it would have more value being able to go up to 4.10 gears. I guess what I'm really wondering is if the 3.23 would be too tall to get any decent mileage when cruising around? Your opinion?

I'm sure I'm confused about something on this, but I'd appreciate any help you can give me on this.

Thanks!

[Tom]

The 3.08 uses the same carrier as the 3.23.Upgrading to a 3.23 will not effect your gas mileage too much.

Tom

['ol Pinion head]

As Tom mentioned, the 3.23's are not going to add many more rpm or provide that much more torque multiplication. In the many rearends I've assembled, going from 3.08 to 3.23 only added a little over a hundred rpm at 60mph. Def a bigger jump in rpm in going from 3.23's to 3.42's (in 8.5 rearends).

[mike nixon]

one other option may be the lok-rite conversion that's out. it replaces the spider gears and doesn't require removal of the carrier asm.

mike

[rand68]

Originally posted by Tom:
The 3.08 uses the same carrier as the 3.23.Upgrading to a 3.23 will not effect your gas mileage too much.

Tom

<font size="2" face="Verdana, Helvetica, sans-serif">Ok it's good to know that it's not that big of a jump, BUT according to my newly-delivered 1968 shop manual I'm not sure I could go to a higher gear ratio. It says on page 4A-1 "Three differential cases, which differ in ring gear mounting dimensions, are used: one for the 2.29, 2.41, and 2.56 ratios, one for the 2.73, 2.93, and 2.08 rations and one for the 3.23, 3.42, 3.55, 3.73, and 4.11 ratios. When changein axle ratios, be sure to us the proper differential case."

Does this mean I should quit thinking and just stick with my 3.08's because I can't put any larger ones in?

I was looking in the Original Parts Group catalog and they've got a Powertrax performance locker for the 8.2" rear-end ($309) with 28 splines. This unit looks different that the Eaton posi unit on the same page. Does it just replace the differential gears in the carrier? Has anyone used one? Are they good? Do they suck? Page 129 if anyone has the catalog.

Thanks!

[goatseeker]

Hey Roger,
Please check your email. Are you gonna get back to me on the disc brake conversion for my '66? I'd like to get the stuff ready so I can go ahead and order brake lines and anything else I might need to put in at the same time. Also wondering if the PST polygraphite front end kits are compatible with most of the reclaimed disc brake conversion stuff on GTO's. If you can't put together a disc conversion for me that's cool - I just need to know so I can order one.
Sorry to change the subject Rand, I've had trouble reaching OPH & thought he might read this.

[mike nixon]

rand68, the powertrax unit is the same as the lok-rite unit i mentioned above.

check the pricing with summit racing, they'll match or beat the competition.

the unit replaces the spider gears in the open differential. mike

[rand68]

Ok a little more searching, and a lot of reading it seems that Powertrax has 2 units, and they're both pretty straightforward to install, and can even be done with the rearend in the car, which is a huge plus IMO. Looks like they have the no-slip unit and the lock-right unit. The No-slip seems to be their newer, better unit, and the Lock-right is their older, function if slightly noiser unit. They seem EXTREMELY popular in the 4x4 crowd. :-)

If anyone's tried one of these let me know how they compare to a regular posi/safe-t-track.

Thanks!

['ol Pinion head]

Goatseeker, Hello, will drop you an e-mail with my phone #.

[ September 07, 2002, 10:27 AM: Message edited by: ol' Pinion head ]

[goatseeker]

Anybody out there had personal experience with the Power Trax "Lock-Rite" unit.
Visited their website and it seems to be a "drop-in" replacement - I like that. Estimate my new motor will have around 500hp and peak torque around 550. Going in my '66 GTO w/M20 and 4 speed so would like to upgrade from 3.55 open diff to posi with same ratio. May make a couple passes just for the record but 99.999% for the street. I'm sure the Moroso/Eaton units are stronger but can anyone tell me how the Powertrax has held up for them.
thanks,
Tim

http://kurtspontiac.homestead.com/TimSimpson66GTO.html