11" drum backing plate - Mystery Solved

dragonvan · Post by **dragonvan** » Fri Jun 22, 2007 6:47 pm

I managed to locate new 11" backing plates for a '96 Caprice through GM Vintage parts. I got them the other day from the GM dealership that supplies me parts and when I opened them today I found two of the same backing plate. This would mean that the park brake cable would enter in the front on one side and the rear on the other. The stock 9.5" drums on my '02 have both park brake cables entering from the front. Was this my parts guy's screw up or do the cables enter from opposite directions on the Caprice backing plates. All that I can find in my manuals makes it look like both should enter from the front like the 9.5's.

I could drill the one plate and plug the hole so it would work with my stock setup, but if there is a different plate I would like to try to get it. If There is a different plate for the right side and I can still get it I can either send back the extra left plate or sell it to someone here if anyone is interested.

Thanks in advance guys
DV

peter · Post by **peter** » Fri Jun 22, 2007 6:51 pm

I'm positive your parts guy screwed up. Leave the swap for another weekend and get the proper backing plate for the other side.

dragonvan · Post by **dragonvan** » Fri Jun 22, 2007 7:06 pm

Thanks Peter. Everything was pointing to that from my viewpoint here but wanted to double check before I called and chewed him out tomorrow morning. I can't complain as the part numbers for the backing plates are listed as discontinued and no more stock in the regular GM parts system. My parts guy at the dealership though is the best one I have ever had anywhere... he tracked down the backing plates through GM Vintage Parts and they still had a few left. Most guys would have just said, "nope, can't get that anymore." and left it at that. He probably spent close to half an hour tracking these down for me so he was probably just in a hurry and accidentally ordered 2 of the same one. I hope that he can track down the right side one too.

No biggie as I wasn't going to install them this weekend anyway, just want them in case I need to throw in rear brakes next week before leaving on the trip... might as well upgrade while at it, and I need to change the rear diff fluid before leaving anyway.

I will have the part numbers for both in my mods list once I track down the other one.

peter · Post by **peter** » Fri Jun 22, 2007 7:11 pm

Well there you go then! It all works out in the end

dragonvan · Post by **dragonvan** » Fri Jun 22, 2007 7:35 pm

I just hope I can still get the other side. If not I will just mod the extra left one and you will never know the difference. It would be nice not to have to spend a half hour drilling, welding, painting though. All I could get in the bone yards around here were whole axle assemblies. I priced it out and I could get all of the parts for the brake swap for about $20 less than a used axle, and all of the parts are new then, not 10 years old. I don't have anywhere to put the rest of the axle anyway so that would go to the recyclers. It already looks like a redneck mansion around here I don't need anymore stuff to sit around.

Has anyone ever thought of trying the 12" drums that were on the G2500 series full size vans in the late 80's early 90's? That is a lot of extra weight to spin up though on take off.

rlsllc · Post by **rlsllc** » Fri Jun 22, 2007 7:46 pm

Since they are so rare, if you do find the other side, buy two; then sell the other ones as a set. I think someone on here would buy them. I've got a set, but have to fill and drill two mounting holes on each one since mine are the wrong pattern

SoCalli V8 · Post by **SoCalli V8** » Fri Jun 22, 2007 8:27 pm

Yep, your parts guy screwed up, do as rlsllc said, you won`t have any trouble getting rid of them.

canadavan · Post by **canadavan** » Sat Jun 23, 2007 8:19 am

Actually, I'm going to disagree and say that the parts guy didn't screw up. I've done this swap and I thought the same thing. V8famvan got backing plates for he and I at the junk yard and I thought that he accidentally gave me two for the same side. So I went to the junkyard. Turns out the Caprices run the parking brake from the front on one side and from the back on the other. I learned this after I'd drilled a new hole in the plate. I set mine up just like the the Caprice (1 front / 1 back) and it works fine. I did have to adjust the mounting point for the parking brake bracket though.

Check out the junkyard before you send those back.

canadavan · Post by **canadavan** » Sat Jun 23, 2007 8:23 am

Also, If you do this swap, make sure to use 7/8 wheel cylinders. The 11" drums came with 7/8 and 1" cylinders. I used the 1" the first time and had lots of problems with my proportioning valve. The 7/8 is the same as the stock drums and the proportioning valve won't know the difference.

Of course everything I'm telling you relates to a 90 Astro...

dragonvan · Post by **dragonvan** » Mon Jun 25, 2007 6:49 am

BINGO Canadavan! I checked with my GM parts guy this morning and he has 3 different parts systems that all list the same part number for the left and right.

P/N 18002392 11" backing plate fits '76-'96 Caprice available through GM vintage parts.

I will put the number up in my mods list with the other stuff. If anyone wants a pair and can't get them locally for some reason let me know. I can't get a price break on these (list and net are the same on my invoice anyway) so my cost is $42.

And thanks again Canadavan for letting us know that the park brake cable is long enough to enter from the rear.

Now which side does it enter from the rear on?

I knew someone would have the answer if I just picked enough of your brains. You guys are great

peter · Post by **peter** » Mon Jun 25, 2007 9:14 am

Incredible. I'd have never guessed. I would still rather drill for a front exit, though. Just don't feel right....

Also having much difficulty in accepting that some tallish freak from BC is right while I'm.....uhhhh, well.....not "as" right as he

dragonvan · Post by **dragonvan** » Mon Jun 25, 2007 10:04 am

You couldn't drill for front exit Peter if there were never any from the factory with a front exit.

If you did you would have to use some other park brake lever as you can't flip over the lever. Even if you were able to find an opposite lever for the right side (GM reuses so many parts I doubt it exists) you would have the issue of leading/trailing shoes being wrong and this could cause a problem during normal breaking and I think when I looked at the shoes at the parts house one has a thicker lining than the other and may not be able to be flipped also.

If anyone wants to try let us know if it works... but I'm not going to put the time into it. Too many if's and trial and error. If there is enough cable for the rear entry as Canadavan says then that is easiest and most time effective.

canadavan · Post by **canadavan** » Mon Jun 25, 2007 5:14 pm

No problem. I think its the pass side that gets flipped around.

I'm not a genius. When I was assembling mine I thought I had two for the same side so I walked across the road to a construction site and got one of the guys there to drill a hole in the "proper" spot, only to realize during assembly that I had screwed up. (The hint should have been that the parking brake actuators were identical. They should have been mirror images otherwise...) Now I have a superfluous hole in that backing plate that I really should plug. Oh well, live and learn and share the pain so shrimpy Montrealers can have their fun at your expense...We Canucks are so complex...

v8famvan · Post by **v8famvan** » Mon Jun 25, 2007 5:44 pm

HA!
I have been gone for the weekend to Whistler & have not logged in till now. I could have told you right away that they are the same PN for both sides. Good to see that Todd set you straight. $\:D/$

dragonvan · Post by **dragonvan** » Mon Jun 25, 2007 8:30 pm

Well I was doing a final brake inspection before my trip... Rocky Mountains! While I was down there I took a quick peak and Canadavan is right. The right (passenger) side is the one for the cable to come in from the rear. Get this, the cable comes around the rear of the center of the diff only to go back to the front side for the 9.5" brakes. It should be no problem rerouting it to go in the rear on that side as it will actually take a couple of bends out of the cable. Go figure.

BTW Todds ALWAYS have the right answer.... hint, hint

Chevy & GMC Vans

Chevy & GMC Vans

11" drum backing plate - Mystery Solved

11" drum backing plate - Mystery Solved