The Stovebolt Site Forums The Shop Area Driveline 66 GMC rear brake problems

I'm up against the wall and need some information and advice.Sorry about the lengthy post.

66 GMC 1/2 ton with a Dana 44 rear differential and leaf springs. No one has rear drums or park brake cables listed for this truck- everything is coil spring only. So I picked up all the shoes/drums/hardware for a Chevy with coils. Put one side together yesterday ( had to grind the park brake strut lever for clearance) , slid the brake drum on and it sits out about 1/2 inch too far from the backing plate- no good. The park brake cable for the coil spring rear end also mounts to the backing plate differently .Thought I could just get a backing plate from a truck with a Dana 44 and coil spring but I'm told the Dana was only used with leafs.I was also told the 66 GMC rear brakes were a one year only design ( with leafs).

Does anyone have a 66 or newer GMC or Chevy truck with a Dana 44 and coil springs or is what I was told true? Dana 44 is leafs only?

Would a backing plate from a GM type differential fit on a Dana 44?

After doing some research I found that a full size 74-83 Jeep Cherokee/Wagoneer brake drum has the same specs but is 3/10" deeper- I haven't actually looked at one to compare it but this is my next option, although I would still have to fabricate a bracket to mount the park brake cables.

I would prefer to change backing plates but I'm at a loss on this one. Has anyone run in to this or do I have the only leaf spring 66 GMC in the world?

does the drum hit the axle flange or is it hitting the shoes first, maybe just a narrower shoe would help. just a thought

When the drum is on the axle flange its too far out from the backing plate and doesn't cover the full width of the shoe.

Dave:
I have two part numbers you can try for rear 6 lug brake drums. The first is a Wagner BD 60089. The second is Allsafe 2067 DGS.

I used the Allsafe from Autozone. It is for a later model (I think 67-72) truck with 4 wheel drive. It has fins on the outside unlike the original that is smooth. The only modification that I had to make was to drill the 6 lug holes from 1/2" to 9/16" so that the drum would fit on the shoulders on the rear lugs like the original. This drum had the right offset unlike the Chivy drums.

The Wagner was a number that I got from another member of the 6066gmcguy.org site. I haven't used that one, but was told it was a direct match to the original (a bit pricey, though is what I remember).

I hope this helps with those looking for rear 6 lug drums.

Regards,

Steve Lorio

New Orleans, LA

Thanks for the info- I checked and the Wagner Bd60089 is obsolete and replaced by PN BD60292. The Raybestos # on this is 2067. The drum has an overall height if 3.55" according to the specs. I've also come up with the Jeep drum which is a Wagner BD60397 or Raybestos 2347. This drum doesn't have the fins on it and height is 3.3" so I'm looking at 2/10" difference between the 2 so will have to do some measuring to see if I have any clearance problems with the backing plate. Did the drum you used have a machined surface for the shoes that goes right to the edge of the drum?

I would still like to change out the backing plate to the chevy style if possible but need to find one ( or dimensions/photo ) of one off of a truck with the GM style rear differential to see if it can be used on the Dana. Anyone?

Dave:
I used the Allsafe 2067 DGS from Autozone. It did have a machined surface that went all the way to the back of the shoes. This was the finned drum from the 67-72 four wheel drive Chevies. I checked the BD60089 on Napaonline and they show the drum as available there with the 3.55" height. I haven't seen that drum, but the person I was helping with that problem said it was a duplicate of the drum he took off. Here's the link to the Napa drums for $54.19:

http://www.napaonline.com/NOLPPSE/(S(i4c5o13qc4bc1455cgg3e255))/Results.aspx?Ntt=bd60089&Ntk=Interchange%20Number&N=0&Nty=1&D=bd60089&Dn=0&Dk=1&Dp=3


Just a guess, but I think the 3.3" height will leave your shoes hanging out similar to the Chevy drum. Have you measured the height of your old one?
Regards,
Steve
New Orleans

Thanks again for all your help. The Napa drum looks to be the same as the Raybestos 2067 at 3.55 high. The drum I have is 3" high so one or the other should work providing there is no interference with my existing backing plate. I'm trying to find one locally to have a look at it but am also heading for the wreckers on Friday to look at backing plates to see if I can go that route. If I can adapt a backing plate it will also help with using the standard Chevy park brake cable.

I'll keep you posted.

Dave:
I used the Chevy parking brake cables on my GMC. The way I did it was to cut a slit on the brackets that hold the cables and slip the Chevy cable into the GMC bracket. Alternatively, you could inlinetube.com make up cables to match yours. I used them to make the intermediate cable to my specifications because the length of it was a bit off due to the Chevy cables on the backing plates.

I hope this is helpful. I think what you have is workable rather than trying to change backing plates.
Regards,
Steve
New Orleans.

I have the axles out and all the parts ( including drums and cables) so if a Chevy backing plate is a bolt on it will be a simple install. If backing plates aren't usable then I'll go the same route as you. I have looked at the GMC cables and had thought of slitting the brackets so its good to hear it can be done. Supposed to be a nice day here tomorrow so I took the day off to head to the wreckers. They have quite a few 60's and 70's trucks there so I shouldn't have much trouble finding what the Chevy backing plate looks like.

I'd like to get the rear brakes done before the snow flies. We've had a very nice fall so far but I know it won't last!

Spent the afternoon at the wreckers yesterday, educational trip if nothing else.

The backing plate from the Chevy differential doesn't look like they will work although the bolt pattern seems the same. I picked up a used Jeep drum ( free) to try it out. The center hole is smaller than the old drum so I ground it out larger so it would slide over the axle but ran into interference problems with my backing plate. Might be able to make it work but only as a last resort.

I'll see if I can find the 2067 drum locally on Monday to give that a try. The drum seems to be quite a bit larger diameter than the original so hopefully will not interfere with the backing plate. I'm guessing it is a larger diameter than the backing plate?

Picked up a dual master cylinder, proportioning valve, and pedal rod from a 68 so I can convert the truck to a dual master cylinder. Looks like I can use the new drums I have for the front brakes.

Success! Thanks Steve. I picked up 2 Raybestos 2067 drums today and they look like they will fit ( after drilling the stud holes to fit over the shoulder of the GMC studs). Comparing them to the old drums it looks like the only difference is in the "finned" area which is large enough to fit over my existing backing plates. That and I had to pay 95.00 each for them.

I just need to fabricate brackets for the Chevy parking brake cables and I should be good to go onto the next project. Pulled the driveshaft ( one piece) to do u-joints and pinion seal and found my pinion yoke is shot. Will it never end?

Dave:
You are welcome. I am glad you have your rear drum problem solved. I remember how frustrating it was when I dealt with it.

What is wrong with the pinion yoke? I have had good luck with pitting/wear on the sealing surface using speedi sleeves. They are a thin bushing that you can pick up from bearing houses for such repairs.

Good luck on your project.
regards,
Steve
New Orleans

Pinion yoke looks like a u-joint let go at one time so is pretty hammered. Shouldn't be too big a deal to get a replacement.
Thanks again for your help. Weather forecast for the next few days looks good so hopefully I can get the rear brakes finished before I have to quit for the winter. I really need to get my garage insulated and heated. I envy you for your winters down there but not for your summers. Years ago when I was trucking I hauled a load into New Orleans in July. Nice city but too hot and humid for me.