brake pedal squeal - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Mondo · 03-09-2019, 10:48 PM

Hi,
I have a 67 with disc brake conversion (disc/drum). I'm getting a kind of squeal (not squeak) from the brake pedal area. Maybe the master cylinder area but hear it under the dash. It's when pushing or releasing the pedal and changes pitch with the pressure.
It's been this way for quite a while. Just got a brake job, new front calipers and new disc/drum proportioning valve but still have this squeal. Also, I have 2008 5.3 drivetrain swap with vacuum hose going to brake booster.

Any ideas?

**Steeveedee** · 03-09-2019, 11:28 PM

It's either the pivot point, or the pin connecting to the push rod. I'd personally spritz a little dry lube on those two location. Might take a couple of applications, since they don't rotate a lot.

Mondo · 03-09-2019, 11:52 PM

Thanks, I lubed the pivot point. I'll try the push rod pin.

**Ol Blue K20** · 03-10-2019, 08:12 AM

Brake booster vacuum leak?

**Sheepdip** · 03-10-2019, 10:06 AM

Quote:

Originally Posted by Ol Blue K20

Brake booster vacuum leak?

My first thought, that or air being displaced by the booster/diaphragm movement for some odd reason and not necessarily a vacuum leak.

Mondo · 03-11-2019, 12:07 AM

I lubed all the pivot points but, yeah, I think it's coming from the booster itself. The breaks don't fade or pedal move while holding it down (like at a stop).
Guess I'll live with it...
Thanks for the comments.

Overdriven · 03-11-2019, 02:33 AM

I’m not sure if your setup has a boot for the pushrod where it goes through the firewall or not but it might be a place to look.

Mondo · 03-11-2019, 11:29 PM

There's a boot where the rod goes in the booster. I stuck the spray lube straw inside the boot and gave it a good squirt as well.
I can say the next day it was much quieter, but still there. The pivots are well lubed and don't want to spray too much in that boot. I think I can live with it...

Never know, some day I might go for hydraulic power brakes instead

Thanks for responses

03-09-2019, 10:48 PM	#1
Mondo Registered User Join Date: Aug 2007 Location: Bakersfield, Ca Posts: 538	brake pedal squeal Hi, I have a 67 with disc brake conversion (disc/drum). I'm getting a kind of squeal (not squeak) from the brake pedal area. Maybe the master cylinder area but hear it under the dash. It's when pushing or releasing the pedal and changes pitch with the pressure. It's been this way for quite a while. Just got a brake job, new front calipers and new disc/drum proportioning valve but still have this squeal. Also, I have 2008 5.3 drivetrain swap with vacuum hose going to brake booster. Any ideas?

03-09-2019, 11:28 PM	#2
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,783	Re: brake pedal squeal It's either the pivot point, or the pin connecting to the push rod. I'd personally spritz a little dry lube on those two location. Might take a couple of applications, since they don't rotate a lot. __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

03-09-2019, 11:52 PM	#3
Mondo Registered User Join Date: Aug 2007 Location: Bakersfield, Ca Posts: 538	Re: brake pedal squeal Thanks, I lubed the pivot point. I'll try the push rod pin.

03-10-2019, 08:12 AM	#4
Ol Blue K20 Proprietor of Dale's Corner Join Date: Nov 2012 Location: Vacaville , CA Posts: 16,271	Re: brake pedal squeal Brake booster vacuum leak? __________________ "Some Days Chickens And Some Days Feathers" Dale XNGH ECV Sam Brannan 1004 R.I.P. 67ChevyRedneck R.I.P. Grumpy Old Man R.I.P. FleetsidePaul

03-11-2019, 12:07 AM	#6
Mondo Registered User Join Date: Aug 2007 Location: Bakersfield, Ca Posts: 538	Re: brake pedal squeal I lubed all the pivot points but, yeah, I think it's coming from the booster itself. The breaks don't fade or pedal move while holding it down (like at a stop). Guess I'll live with it... Thanks for the comments.

03-11-2019, 02:33 AM	#7
Overdriven Registered User Join Date: Mar 2016 Location: Long Island NY Posts: 598	Re: brake pedal squeal I’m not sure if your setup has a boot for the pushrod where it goes through the firewall or not but it might be a place to look.

03-11-2019, 11:29 PM	#8
Mondo Registered User Join Date: Aug 2007 Location: Bakersfield, Ca Posts: 538	Re: brake pedal squeal There's a boot where the rod goes in the booster. I stuck the spray lube straw inside the boot and gave it a good squirt as well. I can say the next day it was much quieter, but still there. The pivots are well lubed and don't want to spray too much in that boot. I think I can live with it... Never know, some day I might go for hydraulic power brakes instead Thanks for responses



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