71oldscutty

I picked up the car a few weeks ago and am trying to get things sorted out before taking it in for floor pan replacement. After changing the plugs the 455 runs and idles like a champ at 750 rpms. I rebuilt the front brakes and the rear drums dropped the car on the ground, put it in Drive and it does a burnout without putting my foot on the gas. Is this a transmission or torque converter issue? I did not get to test drive the car (needs full restore) but the transmission shift cable was unhooked and front brakes were locked up when I got it. Any help or ideas where to start is appreciated.

1971 Oldsmobile Cutlass S
455 TH400
Stock front Disk Brakes, Rear Drums.

coppercutlass

If it has a big cam and stock converter that would do it. If not your brakes are not holding.

71oldscutty

I keep thinking rear brake adjustment as well. Thank you for the reply - I have zero information on the engine. There has to be a reason the previous owner stopped driving it, maybe it was the rear brakes.

Fun71

You're saying the car does a burnout when going from park to drive at 750 RPM idle? I have never heard of anyone doing a burnout at idle speeds, unless it was on an iced road.

Now if it just chirps the tires when going from park to drive, that may be the rear brakes not grabbing sufficiently. My car will do that in the garage when going from park to reverse if I don't hold the brakes firmly. It doesn't do it on street pavement, though.

71oldscutty

Yes. In the garage at idle speed, 750 rpms, in drive the car will spin the back tires. The only thing holding the car in place is the front brakes. I have never heard of it either. Is it because the surface in the garage is slick? I am going to have to give it a try on the street tomorrow.

coppercutlass

It still shouldn't do it I would make sure your back brakes are working. Did you bleed them are the rears getting fluid no pinched lines ???

71oldscutty

I replaced the lines, wheel cylinders (the pads looked good) and bled them. Do they self adjust? I installed the drums where they just clear the pads, but It doesn't seem like they are working as they should. This stuff can get frustrating and I have a long way to go!

coppercutlass

you may have to rebleed. I had an issue where a bad fitting was letting air in but fluid was not leaking. It gave me hell. Do you have a firm pedal ?

71oldscutty

Yes. The pedal was firm halfway to the floor - without going all the way to the floor. I had a helper press the brake with the drum removed and they expanded. How much should they expand? They did not move much.

Fun71

The slick garage floor is what lets the rear tires spin. It shouldn't do it on grippier pavement.

As for the rear drums, there is an oblong adjustment hole at the bottom of the backing plate where you can insert a brake tool or a flat blade screwdriver and turn the adjusting wheel so the shoes are in closer contact with the drums.

coppercutlass

The brakes should hold regardless of surface. Whats gonna happen when it rains ??? Make sure your brakes are good sometimes you think they are snug but they settle in after you press the brakes and you loose that "tightness".

71oldscutty

I don't think my backing plate has the oblong adjustment hole........... I will have to go look again.

Fun71

There should be a hole with a rubber plug in it.

71oldscutty

No sir. I do not have any type of rubber plug or hole in the backing plate. How in the world do you adjust the rear drums? It might be time to just bite the bullet and go to rear disc brakes, which will open up another can of worms I'm sure.

Fun71

There are some setups that have the adjusting hole in the outboard side of the drum itself. Have to remove the wheel to get to the hole. I never heard of that on an 8.5" 10 bolt rear, though.

droldsmorland

Sounds like the shoes are not adjusted up on the drums properly. And you may still have trapped air.

Is this a stock RPO 71 GM corporate rear end?
If so do you see the backing plate in Fun71s pic where the tool is entering the brake plate?? You may need to knock out the factory blanks if they are still there. It sounds like they are. Look for an oval depression. Use a hammer and drift smaller than the blank and smack it squarely. It will bust out. Then install the rubber plugs once your done adjusting the shoes.

With the wheels torqued to spec and both rear wheels (safely) off the ground adjust the shoes so there is a VERY SLIGHT even drag when you spin the tire. You should get about 3/4 to 1 full rotation when you try to spin the wheel. Sometimes tough to feel on the rear wheels.
Driveway Test it. If it feels ok then road test it.

Now you can do the "self-adjusting" or equalizing procedure.
In your driveway or an open lot put it in reverse, foot on the brake and the gas. Bring it up to about 800-1000 rpm, then pump the pedal while going backward for about 50-100 feet.
By pumping the pedal I mean depress...completely... release completely and let the car roll a few feet then repeat for 50-100 feet. This will allow the self-adjusting feature to find the sweet spot. Now raise the rear wheels again and make sure they didn't tighten up too tight. You should still be able to spin the wheels by hand. If not you may need to back the star wheel off a few clicks and repeat the above procedure. This (reversing) procedure should be repeated every so often to keep proper adjustment. This only works if the hardware (springs, retainers, star wheel, shoes etc) are clean lubed and in good serviceable shape. A hardware kit is cheap. So are adjusters. Grease the three contact areas on the backing plate where each shoe makes contact.

This is as good as I can describe the procedure. It's a "feel". Get yourself a couple of good shop manuals for this car and do a youtube search for some visuals. Shop manuals are available everywhere. Get a Fisher body manual and a 71 cutlass assembly manual.

If you get it wrong the car could fishtail during a panic stop. Again find an open space get it up to 30-40mph and stand on the brakes. You should get a nice even straight stop and 4 tire marks. AHHH Zero anti-lock brakes are a thing of beauty.

Note 1: Always disassemble one side at a time so you can reference the other side.

Note 2: Verify you have the primary and secondary shoes in the right position. Look at the shoe linings. See two are longer two are shorter....The primary shoe is the shorter one and goes towards the front of the car. A good shop manual will outline this as well. Be safe good luck. Let us know if this info was useful or useless.