For a 1970 Cutlass - stock front disc
In preparation for removing my front disc pads could anyone advise on the size of C-clamp that I will need to compress the pads?

 

I just use channel lock pliers.

 

A 6" clamp comes in handy for many things around the shop. Channel locks should work fine but make sure you take the reservoir cap off or you may not overcome the pressure within the system. I would use a plate over the piston cup to avoid damaging it and to depress it evenly.

 

Thanks!

 

 

^^^I just bought a pair of those vise-grips...usually I use channel locks..

 

Remember to do one side at a time. If both calipers are removed you could push the piston out the opposite caliper while compressing the other.

 

I use one of these. It is about $18.00 on Amazon. I have had it from the days when I had my Corvette. Works great.

 

I realize the question was what size C-clamp, which has been answered...a couple of ideas/comments are if the piston is pushed back while the caliper is mounted in place it will push the bushings that the retaining pins go through into position for an easier re-install of the caliper. Not a big deal just a little easier because it positions the piston and retaining pin bushings in one maneuver.

If the bleeder screw is opened before pushing the piston back it will let the fluid out at the caliper and prevent the dirty fluid in the caliper from getting pushed backward into the master cylinder. This method may require bleeding the brakes afterwards, your call. Use a hose on the bleeder screw to direct and help catch he fluid.

Good luck!

 

I use a 10" C-clamp to push the piston back in the caliper after removing the pads. Frankly, that would be a monster set of channelock pliers. I ALWAYS replace the O-rings, bushings, and bolts when replacing pads to ensure that the caliper slides smoothly. This is cheap insurance against abnormal pad wear. I also NEVER open the bleeder screw when compressing the piston. The fluid flows out and back into the master cylinder when you use the brakes normally. If the fluid is that crappy, flush the system. Otherwise, don't take the risk of allowing air back in. Also, be sure to crimp the tabs on the outboard pad against the caliper body to avoid rattling.

 

Really sound advice Joe has given here. The last thing he mentioned is the thing most people don't even know about...clinching the tabs on the outboard pads. That's important, stops the pads from dragging, rattling, wearing unevenly, etc. There are also inboard pad support clips and wear clips that squeal. They are really simple to work on, but people just buy pads and throw them in w/o considering the other stuff.

 

Thanks Joe.
The service manual procedure calls for the caliper to be depressed before removal and I am going to follow that route. The manual also highlights the need to replace the sleeves and the bushings during installation but I did not think of the bolts. I will add them to my list.
What O-Ring are you referring to, are they the "bushings" as referenced in the manual?


I have been able to source the sleeves and bolts at InLine Tube, but have not been able to find the bushings anywhere.


Can anyone help me there?


Also, the manual calls for lubricating the sleeves and bushings. I was going to use silicone grease because of the rubber bushings; or should I use regular bearing grease?


Also in regard to the tabs, I had an issue with my current system wherein the outboard pad was slipping radially and grinding into the hub because the tabs had not been bent down. The service manual is very clear on this. Here is a thread on that: https://classicoldsmobile.com/forums...-growling.html

 

The "bushings" are actually O-rings.



Only use silicone grease on rubber parts. Petroleum-based grease will attack rubber, causing it to get gooey. The bolts are actually the sliding surface for the calipers, so it's always a good idea to replace them. The sleeves simply extend the length of the head of the bolt for the inboard o-rings, er, BUSHINGS to slide on. New bolts also reduces the chances of rounding out the allen recess next time. Of course, so does a dab of anti-sieze on the threads.

As for compressing the caliper prior to removal, that is usually necessary to some extent due to a ridge on the outer edge of the rotor. I typically use a large screwdriver through the hole in the caliper - tip of the screwdriver in one of the cooling slots in the edge of the rotor to avoid damage to the friction surface. I then use the C-clamp to fully seat the piston after removing the pads.

 

20" BigAzz Tongue and Groove Straight Jaw Plier...AKA Big AZZ Channel Locks. Never leave home without em. Handy for stubborn beer bottle caps too!
Flip over the old inboard pad and squeeze. This allows me to feel the piston. If it doesn't move smoothly the caliper gets rebuilt/replaces too.

 

Excellent Joe. I found this on Summit Racing:
http://www.summitracing.com/int/parts/dhb-hw5500

 

FYI, that same kit is only $2.00 at RockAuto.

 

You win, Crocodile Dundee...

"That's not a Channelock. Now this, THIS is a Channelock."

 

Oh well, I already ordered in from SR, along with the bolts and the Bendix CT-3 pads.


I am going to try and do a video of my effort and post it for critique.

 

I know this is about older disc systems, but I have been told and believe that on anti-lock systems it is better to open the bleeder then to push the fluid back. I do this on older ones now, and close the bleeder before removing c-clamp or whatever device used to compress the pistons.

 

I replace pads on modern ABS equipped cars often at work, I simply push the calliper back with a pry bar against the old pads, clean up the callipers and reassemble with copper grease on the sliding parts, using new bolts if supplied.
Or if the e-brake is part of the calliper wind the pistons back using the correct tool, which won't apply to any except the last generation of cars called Oldsmobile.
Changing the fluid and/or overhauling the calliper every time the pads are replaced is a laudable practice, but not really necessary in most cases, and not practicable in a car repair shop.


Roger.

 

I would believe what the factory writes in the factory service manual, now what somebody in a shop says. I have manuals for all of my vehicles, and nowhere in any of them (including the newer cars with ABS) does any factory manual say to open the bleeder screws prior to compressing the pistons, period. That's only a recipe for allowing air into the system.

Once again, under normal operation, brake fluid flows into and out of the M/C and wheel cylinders. Why is pushing the fluid back one time when doing the brakes any different that when it happens thousands of times while you are driving (and especially with ABS where the pump pulses the fluid to the wheels)? If you are worried about crud in the fluid, you have a much bigger problem and had better properly flush the system. Otherwise, don't open it.

 

I've got a few friends that are mechanics and they all tell me you should always open the bleeders in modern vehicles with ABS as you can ruin the ABS pump by pushing contaminates back through the pump

 

Yep I always open the bleedscreen on ABS systems. I just picked up one these.
$5.99 at harbor freight. Been using the big *** channel locks or C clamp.




Pat

 

I'm still trying to understand why you all aren't bothered by the fact that those "contaminants" flow in and out of the M/C and the ABS pump every single time you step on the brakes. And the factory manual for my 99 Chevy truck with ABS and my 93 Caddy with ABS do not call for opening the bleeder.

Sorry guys, but I'll bet with the factory every time.

 

I likes to take the bleeder right on out after pushing the piston down in.

Then I clean it real well, wire brush as needed, slather it with antisieze so that next time it comes loose easy too.

When done, bleed the brakes a little, or a lot after removing the black gunk from the master if it's that bad, and have solid firm brakes with bleeders that resist rust. Bad experiences early in life with broken off bleeders. Followed by more and more twisted off parts and lines which becomes an all day expensive project for an old pc of crap vehicle

 

I just did a Google search and virtually every do-it-yourself website says not do force the calipers open because of the possibility of introducing contaminants into the ABS unit


Here's just one:


http://my.cardone.com/techdocs/PT%2012-0001.pdf

 

You can do a Google search and find out that headers don't fit Supremes...

Just sayin'

Again, show me where the people who actually designed the car say to do it that way in factory literature.

 

IMO it is no big deal to release the bleeder and get rid of some of that old brake fluid in the cylinders. It is however difficult to rid yourself of that pesky air bubble caught in the upper part of the brake cylinder. The best way to do that is to have a professional brake fluid kit that pumps fluid back though the system and allows the air bubbles to expel from the master cylinder. To Joe's point the fluid circulates back to the master cylinder anyway. Most shops will not add brake fluid these days since it generally means you either have a leak or you pads/shoes are worn and need replacing.

What was the question again??😀

 

Which ironically is EXACTLY what opening the bleeder was supposed to prevent...

Using the "don't push the brake fluid backwards" philosophy, the only way one could ever use one of these reverse bleeder systems is to totally drain and flush the system before using the tool. I'm SURE the mechanics who espouse opening the bleeder also follow this procedure.

I'll also point out that if you look at the hydraulic diagram for an ABS pump, you'll find that they typically have bypass passages with a check valves in parallel with the hydraulic pump such that when you release the brake pedal (or compress the pistons in the calipers) the fluid going back to the M/C bypasses the ABS pump anyway, thereby negating this whole concern.

And finally, since the OP was asking about a 1970 Cutlass with stock disks, none of this discussion applies anyway!

 

Absolutely, Joe!.

Another point against opening the bled screw, from the KISS school of workshop practice;
It is making another (unnecessary) operation in the procedure, therefore introducing an opportunity to do something wrong.

Roger.

 

Thanks! Seriously, I have a pair. I broke the set I bought back in the 80s and bought another set 10 years ago. Dam things do come in handy in NYC subways and outback walkabouts...

 

Through all this discussion, nobody thought to bring up the service interval for doing a brake line flush. Brake fluid is not eternal. Gotta think that (as Joe said) if you believe there's contaminants in there capable of doing damage to the ABS .... why the hell aren't you getting them out while you're there? A 4 wheel flush is NOT that big a challenge. If you're ready to pop a bleeder to run your pads back, it's maybe 2 minute extra work to finish the job and leave yourself with brand spanking new fluid all the way to the taps and a rock hard brake pedal. A $2 turkey baster is all it takes to suck all the old fluid outta the MC. From there, half a dozen pedal pushes and you're clean all the way back.

 

Do I detect a guilty conscience? I know I have one LOL��

 

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HA Professur agreed! I think because were tired of repeating ourselves...liken it to the offset Supreme engine for headers question. Plus the parts-n-service industry would no longer thrive due to the lazy or uninformed or Darwin award contestants. Reference: "The wall of shame thread" (Classic Oldsmobile).

But your right, we should mention it... Brake fluid should be changed ~ Biennially or 50-60ish K miles(or whatever it says in your ops manual as synthetic lasts longer). Moisture absorption and sediment contamination are the big killers of brake fluid and system components.
Most people never change any fluids except engine oil. Retentive mechanics such as myself change all fluids at or before the recommended intervals, to include brake bleeding, power steering fluid and the all important directional flasher juice.
Preventative....not reactive maintenance. That's why I get 300K out of many of my vehicles with the rare major component failure every now and then..such as light duty auto transmissions with a 120K life expectancy(think front wheel drive junk). I can get them to go another 75-100K with regular filter -n-fluid changes. I have a 95 GC Jeep with 228K on the clock with 4 original calipers. And I done live in Phoenix.
Motive brake bleeder with all the adapters to fit many master cylinders is one of the best tools I've purchased. I can bleed brakes in 30 minutes if all things cooperate.

 

New pads are in with no issues. I used the procedure as per The Service Manual and had no problems.
I installed the Bendix D52CT pads.
Hopefully no more squeaky brakes and a little less dust.
Now I have to wait till May to see if they work!