kishy's 1985 Country Squire

[DerekTheGreat]

Sad when you realize you're getting old, the treasure yards are drying up and that it's getting harder and harder to drive the stuff you like to drive. I remember when they were just "20 year old used stuff."

[gadget73]

sad when the "good" parts are 30 year old used salvage stuff.

[DerekTheGreat]

Keep your eyes peeled for a nice one at a treasure yard. Dats what I did when I had to put drums on the '92 C1500 I managed. Aftermarket part quality is indeed shit, but I don't know how comfortable I'd be running that ground down drum. I imagine if you get it hot enough, it'll warp, especially if it gets wet after getting hot.

[gadget73]

thats a good point too, if its touching / not touching repeatedly it will make it shake.

i get that castings can be off center but the machined surface should be true, unless they center it on the OD rather than on the bolt circle. That would be dumb.

[Kodachrome Wolf]

While I was working parts, I’d offer to cut new drums before they even left the store. Virtually not a single one was properly round. They would drag rotationally otherwise on a car until something wore down enough.

Absolutely awful castings in that regard, but usually after they were cleaned up, they worked well without vibration issues.

[gadget73]

if you really want to balance it even better, attach a weight on the face in the area where it got thinned out. Not sure about welding or brazing for risk of warping the thing but I bet you could clean the face up with a gasket grinder and JB Weld something in place to get it pretty damn good.

being off center has a fairly big effect on the balance too. Its not just the weight, but the circle the mass rotates in.

[kishy]

Interesting seeing the feedback this has gotten. The friend who ground it down posted the pics in a prominent Facebook group and got absolutely roasted for it - as he knew he would - with lots of "why not just buy a new $20 drum"-type remarks.

First: there haven't been 20 dollar drums at retail in 20 years. Maybe 30. Maybe never.
Second: by several anecdotal reports, it sounds like even if you spend real money for your brake parts, most new rotors and drums are cheaply-cast trash and it's hard to get anything where the concepts of precision manufacturing or employees taking pride in their work were remotely considered.

There is definitely a risk of heat-related cracking in the area that has been thinned out, and there is also a risk that there could be a casting void somewhere opposite that area. Although it is visibly drilled off-centre, I don't think it's off by enough to make up that much weight all by itself, so there could be another issue hiding within. Additionally, we only got it to 1oz off, and at "well above highway speed", there is a wheel-speed-related vibration that does come on. But that speed was only reached to try to feel out where the vibration went (the result being "it moved up on the speed scale"), and isn't a speed I drive at.

I do have two more of the same drums new in box still, for my other axle with 11" brakes (which is currently not on a car). The plan is to run those on the balancer to see what we find.

I let one of my American friends drive the car today during our junkyard and food travels. He is thoroughly impressed with all aspects of it. He's wanting to pick up a Caprice wagon in comparable condition now...but that's a tough thing to find. The condition of this car is hard to match.

[GM_Guy]

I like your fix.

[Mainemantom]

My 90 CV has a noticeable vibration at 45 mph. Most noticeable when it is not in OD. When in OD the vibration is minimal.
Never heard of brake drums being the problem. Interesting fix.

[Tiggie]

Weight reduction and smoother ride, a win-win. Makes me want to check my brake drums. Both mine have vibes 60mph+.

[gadget73]

something I find amusing is that people will tell you that rear wheel balance doesn't make any difference on a solid axle car that is used at normal highway speeds. Never even heard of anyone mention drums. Clearly the theory that balance in the back doesn't matter is nonsense.

I mean it makes perfect sense, get it far enough out of whack and it wants to run in an oblong, not rotate in a circle. I'm sure its less critical than if it were up front, but nearly 7 ounces out is pretty significant.

[87gtVIC]

That is some find and solution you have there. Who would ever have thought that would have been the problem...aside form whoever it was that mentioned it could be the brakes. Damn.

[kishy]

That photo on the fogy roadway is just too damn nice.

Thanks, I definitely like it. It has some typical "phone camera" issues like the band of light across the top due to the street light, but that's one I like a fair bit.


Revisiting the vibration issue.
History: significant whole-car vibration coming on at higher road speeds and very intense at highway speeds.
U-joints new before I put the car on the road initially.
Chasing this, I swapped wheels and put on new tires, no fix.
Rebalanced the wheels 2 additional times, one with a different balancer, no fix.
Replaced transmission mount, no fix.
Swapped driveshaft, U-joints and yokes from the 86MGM (also new U-joints), no fix.
I had put the rear end of the car in the air and ran it up to speed and observed with the axle hanging (frame on stands), the axle violently shook.
It had been suggested here that it could have been the drums. Whichever one of you said that, give yourself a cookie.

At my friend's shop tonight, we jacked the car up and removed the wheels and drums. No vibration.

We put the drums on the wheel balancer. Driver side first. One factory-installed weight already exists, I'll guesstimate it at 1.5oz. The balancer indicated this drum was 1.5oz out of balance, immediately beside the existing weight. Comparing against the other drum, the other one has two weights, so it's possible one fell off/was poorly welded on/maybe got forgotten on this one. As a temp fix to test if it makes a difference, we put on 1.5oz of sticky weights on the outside of the drum in the right spot.

We then checked the passenger side drum. 6.75oz.
Six point seven five ounces out of balance.
Visible runout when it spins, too.
Seems the cast part was drilled off-centre.



At this point we started pricing brake drums. However, wanting to determine this was the sole cause, we decided to bring it into balance by taking some material off and seeing how it behaves.

After a lot of grinding, we got it down to the point of only being 1.00oz off, and decided to give it a test drive. Smooth as glass all the way up to, at, and well beyond normal highway speed.

Always worth remembering that just because it's new, it isn't necessarily good, and that absolutely can apply to a simple cast and machined part such as a brake drum.

I'm going to run this as it is now. Plenty of thickness left on the drum, I'm not worried about cracking it. It is ugly but fortunately nobody can see it. Except you. Shhhhh.

[87gtVIC]

That photo on the fogy roadway is just too damn nice.

[kishy]

Cruise is maybe not fixed. I found a specific speed yesterday, I think about 55MPH that just wouldn't hold, while faster would hold but traffic conditions had me wanting to fall back a bit. More investigation required.

Early yesterday morning, I was up to wash the wagon and get it to registration for the Detroit Concours d'Lemons. I had gone to bed for a nap Friday around 6PM and didn't wake up until 3:30AMish, so naturally, I was washing the car at about 4:30AM...and from there I was up for the rest of the day. Consequently, I slept great last night.

I took advantage of the totally deserted late night carwash experience and filled a bucket to use a wash sponge. I also peeled off a lot of the plastic wrap from the aluminum borders on the woodgrain which really cleaned up the appearance. There was a lot of dirt under the plastic.