8 1/4 Trac Lok rebuild

88_AHB · Aug 9, 2020

Hey everyone,
I've decided it's time to rebuild my 8 1/4 in my 88. I popped open the cover only to find it has a open diff,thought being a AHB car it would most likely have a suregrip. Anyways I acquired a Trac Lok carrier out of a 96 Dakota.

My question is,
are the Trac lok carriers rebuild able? I see rebuild kits for the dana 35 but haven't seen any for a 8 1/4? Overall the carrier is in decent shape but I did see some scrapes in the center of a couple teeth in the spider gears nothing big. Didn't know if this was something to be super concerned about? I can try and post a few pics of what I have.

Secondly, I have a 904 currently and been debating about what gears to run. I've been bouncing back between a 3.21 or 3.55 yukon or motive gear set. I have a 318/904 2500 stall with a 225/70/15 tire.I realize 3.21 for a little less rpm and economy and opposite for the 3.55. I've also been reading on here of a few people doing a A500 (42rh) swap into their FMJ bodys and have pondered the idea of it. The cross member mods doesn't look terribly too hard to do but, not sure on any trans tunnel mods etc. This thought has also hindered my selection on gears in case of doing so.Any help or advice would be appreciated.Thanks

Duke5A · Aug 9, 2020

I can't speak to the axle, but I can offer advice on the rest. Whatever you do, pick a plan and stick with it. I've been through four motors, three transmission and two axles in my car. I'm happy now with the setup, but spent a lot of money doing things multiple times over to get there.

An A500 with a 4.10 or 3.91 gear is great for these heavy cars when powered by a small block. With OD the final ratio is 2.94, so plenty livable on the highway, but loads of fun in town. I would give serious thought to this. Before going into the axle look into the trans swap. If it is something you decide not to do then you won't be out any money on parts for the back end.

88_AHB · Aug 9, 2020

Thanks Duke,
Thats what I'm trying to avoid is doing something multiple times over. I rebuilt the 904 at the same time I did the 318 I maybe have a 1000 miles or so on both currently. I went with that stall anticipating changing the ring and pinion. Right now it either has a 2.54 or 2.7 gear? It's sort of odd driving it with that stall with these gears.
What sort of modifications to the trans tunnel and cross member would be needed for a A500? I looked at both transmissions and looks like the A500's mount sits a few inches further back is the main difference. Fitment in the tunnel might be tight? or some some massaging of the tunnel might be in order?

Duke5A · Aug 9, 2020

No tunnel massaging is required to fit. The forward half of the 500 is exactly like a 904. The cross member is your problem as it interferes with the OD section (tail shaft) of the transmission. That cross member needs to be flush the sheet metal and while I've seen a few different takes on it, the easiest is to remove it, cut a channel out and put in a piece of formed box tube in its place. This will make the cross member poke up through the top of the floor rather than hang down under the sheet metal. Carpet covers it and you would never know it's there.

You can modify your existing transmission mount or build a new one. The rubber is GM universal piece that bolts right to the bottom of the transmission.

You are going to need a welder and an angle grinder with cutting wheels. A drill too to get the spot welds out. This isn't that bad of a job really. If you know someone with fabrication experience and a garage you can have it done over a weekend.

80mirada · Aug 10, 2020

what mine looks like, ignore the screws.

88_AHB · Aug 11, 2020

Wondering if you have before and after pics? I was trying to find your thread on this conversion.

Also, Curious what were all the screws used for? Thanks

80mirada · Aug 12, 2020

The screw held various items and covers to the floor, they are going to be welded up soon. Unfortunately I do t think I have the before pic

88_AHB · Aug 16, 2020

Thanks 80 mirada,

I was able to take some pics of the 8.25 carrier out of the dakota. Upon closer inspection I found some interesting wear in the spider gears. I'm wondering if they could cause issues down the road and should go another route for a LSD if I cant find a rebuild kit? I know there's new units for around $350-400 but, didn't want to get my hopes up and invest anymore in it if this isnt a worthwhile option.