[67GP428]

Been finishing up the loose ends on my 65 2+2. It's has a HO motor built by other? Working on adjusting the Power drum system. Only getting 10 psi of vacuum. Brakes when warmed up tend to grab. It's that a vacuum or adjustment type issue?

[Geoff]

That is a brake issue, not vacuum. If drum brakes, shoes may be rubbing or be contaminated [ oil or grease ]. These are most likely, but other things could also cause grabbing.

If disc, piston might be sticking.

[alleyCat]

Check and make sure your primary and secondary shoes are in their correct positions too along with the proper left and right orientation of the star adjusters.

[67GP428]

I will double check the shoes. Also a ordered a Crane Cam Vacuum canister. Watched so UTube videos on that. Will give more updates soon. Thx.

[Lemans64]

Low vacuum will make your brake pedal very hard to push.

[67GP428]

The brake pedal is had to push at idle and get a little better when driving. Then gets harder to push coming to a stop.

[Lemans64]

If it's a vacuum problem, the pedal will good while the vehicle is in decal mode, but if using brakes lots going down a hill slowly the pedal will feel
hard, not enough to make it work correctly. The reservoir should help a little with that, but for grabbing, I would think you either have bad adjustment
or bad shoes, shoe to drum contact bad. Does it pull left or right while doing this? I am assuming this is a 4 wheel drum system?

[Geoff]

The vac tank does not increase vacuum, it just 'stores' what vacuum there is.

So hopefully you will have enough reserve before you go under the rear end of that semi....

[67GP428]

The brakes do pull to the left. Brakes have no problem stopping the car. Do you feel the grabbing brakes when warmed up is due to being adjusted too tight? It is a new parts and I feel they need to break in and seat? I feel the vacuum canister will help at idle?

[67GP428]

I used my temperature gun to check the temperature only all drums. Left was the hottest. Rears where cool. I bleed the brake system. Adjusted the right front and both rear drums. Road test this weekend.

[PontiacJim1959]

Originally Posted by 67GP428

I used my temperature gun to check the temperature only all drums. Left was the hottest. Rears where cool. I bleed the brake system. Adjusted the right front and both rear drums. Road test this weekend.

My experience has been related to the brake friction material. If you get the 'best" lifetime shoes, or discs pads, they are metallic and a hard material. They stop poorly on drum brakes and wear out drums and rotors. This is great for the parts sellers as the shoes/pads are lifetime warranty and cost nothing in reality, but they make their money on the new drums/discs which have gotten eaten up by the hard metallic pads.

What I have found, even with my contemporary cars, is to ask for the base or inexpensive line of shoe/pads. They seem to have less metal, are softer, and stop way better. They don't chew up my rotors and I can/have put 3 sets of pads on 1 set of rotors on a former Toyota.

I don't have much experience with the newer ceramic pads, but my 2015 Hyundai has them. They seem to wear well and they do stop good. I replaced my front's at 80K and they were at 1/2 life. Now I bought the car with 30K, so maybe they were replaced. Rotors looked perfect. But even 50K and 1/2 life seems good to me. So another car I just slapped new pads on with the original rotors. 130K miles and no issues.

I did get ceramic front pads for the disc brake conversion I did on my '68 Lemans, but it is not road ready yet and will still be a few years to completion, but I thought I would try a set.

[flat-bill]

I don't want to be the dictionary **** but vacuum is measured in "inches" as in 17 inches of vacuum.

[67GP428]

Lol. Listen to mean not what I say. Still learning the correct lingo. I do have the more expensive shoes. The sure grab!!!. The shoes are installed correct. Probably try a cheaper style of shoes if my problem isn't fixed.

[Geoff]

Shoes adjusted too tight can definitely cause the car to pull to one side. More likely to happen once the car is driven for awhile & the shoe[s] heat up.

Shoes that are rubbing on the drum can be caused by things other than adjustment. Corrosion in the wheel cyl might be preventing the piston from fully retracting, keeping the brakes 'on'. Sediment/sludge in a brake hose or line can cause the same thing. Weak brake shoe return springs.
Rare [ but I have had it happen ] wheel brg comes loose in the hub & wears the hub; drum 'wobbles' & rubs on the linings.

If you do not have automatic adjusters, well worth buying the kits.

[67GP428]

I have 100% new brake system, lines to springs and everything in between. Might just have to break in?

[Lemans64]

New drums as well?? Or just machined? New stuff can take a bit to match, causing pulls and such. How are you adjusting them?
Should adjust until they lock then back off till free, usually counting the number of teeth on adjuster to make the opposite side the same.
For front it is critical. This is why most people convert to Disc brakes.

[67GP428]

Four new drums also. I'm still getting the rub then spin easy when turning the tires. Witch makes it hard to adjust. Hoping a little more drive time will help the go away. What about going in reverse and braking so the self adjusters will help set the tension on the drums?

[Geoff]

Yes, driving in reverse & applying the brakes is how drum brakes with self adjusters adjust the brakes.

It would be a good idea to back off the adjustment slightly & then do the above self adjustment. This would ensure the brakes are not too tight.

Grabbing when hot does sound like adjustment is too tight, especially with all new parts.'

If the problem persists, you might want to swap left & right side brake shoes to see if the problem swaps sides. That would indicate faulty shoes or linings.

You could also swap drums first in case one is out of round, easier to do.

Nothing wrong with drum brakes.

[GOAT8U2]

Trying to stop a 3700lb+ car with 10" of vacuum was just plain insane, I went to a Hella UP28 Pump and now at 21" of vacuum it stops incredible along with the brake updates too. Actual stops better than my 2009 Lancer.

Pump model and pic below, stopping is the best mod you can do for yourself, your car and others.

[george kujanski]

"Nothing wrong with drum brakes. "

Geoff, generally, I agree, however, back in the day when I had manual drum brakes, doing a panic stop from speed was very exciting after the first few seconds.......noticeable fade....

George