In the process of exploring a change in the gear ratio. A couple of question cropped up.

1. There seems to be a special shim kit you have to use for 65-67 chevelle 12 bolts. One of the suppliers I was looking at said that for a 65-67 12 bolt I had to order the factory side shim kit for chevelles with one (1) thin steel side shim as opposed to a super shim kit. Anyone with any experience regarding this information?

2. Can I leave the rear axel assembly installed in the car to swap gears? Or is this just to difficult to do it this way and you must pull the axel assembly?

Thanks,

james,
they are correct about the shims. i have found the 65-66 and early 67 used the thin .063-.110 shims. they are no longer available that i know of. i do have a very good stash of used and mostly nos pieces. it is always easier to do out of the car. bring it down to dysart and i will help you get it done.

better yet drive it down. tom

Sounds like a option I will consider. Thanks much. Jim

looks like ad is no longer there. Found a couple of places that sell the side shims, .064- .094 (sizes increasing by.002; but excluding .070,.072, & .076). Wonder why those 3 sizes are not available? Anyone?

Tom, have you tried using a different bearing race? I think the 12 bolt uses the LM603011. I plan on trying the LM603010 the next time I build one of the old 12 bolts and see if the super shim set will work with them.

the link to the ad on TC doesn't work.

I have not done a 10 or 12 bolt but have done the brand F equivalents. Reider Racing has always had some neat shim kits with a base shim that you stack the appropriate combo of shims on to get the correct set. Try them.

Those shims are too thick for the early 12 bolt. The only shims that work in them are the GM shims, which have been discontinued. If you ever get into one of them you will understand.

I had the same problem with my 66 chevelle. The funny thing is I called all around, and nobody had heard of this problem. I tried to buy the right shims from the chevy dealer, but they were discontinued. I ended up using a bunch of little shims. I know its not the best idea, but didn't have a choice. I did find some shims for 2000 and newer vehicles, but they were priced at about $150 for two shims. I even bought a new carrier to see if that was the problem. I talked to a guy at richmond who said he has rebuilt over a thousand 12 bolts and never had seen one that wouldn't take there shim pack. Shows how much he really knows. I am just glad to know mine isn't the only one.

So when trying to center the differential, I need to use one shim per side. Then must I have a bunch of shims on hand inorder to get the right size. Or is there some way I can use what I presently have in there to get an ideal of the sizes i need? thanks.

to do it right and quick, you will need a large selection of these shims. as i said before. i own a large selection of these shims. every size needed.

you could try with your old shims. you may get lucky, i never do. do not throw the old ones out.

BHG and i are working on a possible cure to this problem. tom

I would be, but I don't have an early housing to work with.

Tom, your ad doesn't seem to work? Also when you mention you would help me get it done, Maybe you could send me a PM regarding cost? Thanks to all.