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Brake Problem 10 Years, Never Solved! - Clevis Adjustment?

Posted by Dave Plummer <iframe src='https://members5.boardhost.com/impalass427/info/user=davepl' width='330' height='300' border=0 style='border:none;'> on 4/13/2018, 11:09 am

I have had a problem - slow to react brakes - for years ever since I first put rear disc on. I've long since taken those off, and now the system is a complete Willwood setup, but the problem remains!

Here's the problem:

The brake system does not respond quickly enough for panic braking. Although the system is able to provide full lockup it takes a couple of seconds for braking force to build.

Another way to describe it would be that the pads feel like they're made out of wood and don't bite/grab the pad at first. We've tried several different pad types (organic, metal, semi), and it seems not related.

It feels as though the brake fluid is being forced to operate through a very small orifice, so that it takes time but ultimately has the full force.

Last time the car responded properly was factory drum-drum.

I then upgraded to factory front disc and mid-80s rear disc, with Corvette master, and that’s when this all began.

Ultimately the entire braking system from the pedal forward was replaced with Willwood, and the problem remains! So the only parts that remain from the problematic system are the pedal, the pedal box, and the pushrod.

The brake pedal rides about equally high as the clutch pedal, so I don’t think it’s wildly out of adjustment. But could a maladjustment of the brake clevis, and hence the brake rod angle, cause any of this?

Any other ideas that don’t involve lines, master, or the brake themselves?

Remember, new rotors, pads, mounts, lines, master. I've tried a hydraboost in place of the vacuum booster, same result (but then a but more assist once it gets going).

(no subject)

Posted by 1969copo <iframe src='https://members5.boardhost.com/impalass427/info/user=1969copo' width='330' height='300' border=0 style='border:none;'> on 4/21/2018, 7:21 pm, in reply to "Brake Problem 10 Years, Never Solved! - Clevis Adjustment?"

Re: Brake Problem 10 Years, Never Solved! - Clevis Adjustment?

Posted by TRQ <iframe src='https://members5.boardhost.com/impalass427/info/user=trq427' width='330' height='300' border=0 style='border:none;'> on 4/20/2018, 6:20 pm, in reply to "Brake Problem 10 Years, Never Solved! - Clevis Adjustment?"

If your stopped on a steep hill,and let off the brakes,do the brakes immediately release and let the car roll away?

Re: Brake Problem 10 Years, Never Solved! - Clevis Adjustment?

Posted by Nick <iframe src='https://members5.boardhost.com/impalass427/info/user=427impalasportcoupe' width='330' height='300' border=0 style='border:none;'> on 4/20/2018, 9:49 am, in reply to "Brake Problem 10 Years, Never Solved! - Clevis Adjustment?"

Corvette brakes were the hardest to bleed without a power bleeder. The manual shows You what play the rod and master should have. Too tight and the brakes will grab, and to loose and the brakes will not have full power. It does depend on the amount of vacuumn the engine has. My brakes would fade from the factory at a high speed stop because the L72 did not have enough. A vacummn pump would be a good choice. Willwood should have the answer. NICK L72

427impalasportcoupe

Re: Brake Problem 10 Years, Never Solved! - Clevis Adjustment?

Posted by Joe Pesch <iframe src='https://members5.boardhost.com/impalass427/info/user=jpesch' width='330' height='300' border=0 style='border:none;'> on 4/18/2018, 10:26 am, in reply to "Brake Problem 10 Years, Never Solved! - Clevis Adjustment?"

Hello Dave, new member here. Was your car originally a power brake car?

Re: Brake Problem 10 Years, Never Solved! - Clevis Adjustment?

Posted by Dave <iframe src='https://members5.boardhost.com/impalass427/info/user=davepl' width='330' height='300' border=0 style='border:none;'> on 4/18/2018, 10:31 am, in reply to "Re: Brake Problem 10 Years, Never Solved! - Clevis Adjustment?"

It was, power drum-drum. The problem FIRST started when I put an MPBrakes rear disc kit on the rear, but it never went away when I replaced all those parts.

Now it's a totally different master, prop, lines, and calipers and rotors and tires and the problem remains, which is why I'm stumped!

It's like the damned rear discs were a virus my car caught that won't let any other brake work right!

Re: Brake Problem 10 Years, Never Solved! - Clevis Adjustment?

Posted by Bruce <iframe src='https://members5.boardhost.com/impalass427/info/user=bowtieguy45' width='330' height='300' border=0 style='border:none;'> on 4/17/2018, 11:12 pm, in reply to "Brake Problem 10 Years, Never Solved! - Clevis Adjustment?"

Hi,did you change out to a proportioning valve from the metering block that came with drum/drum?

HEARTBEAT OF AMERICA

Re: Brake Problem 10 Years, Never Solved! - Clevis Adjustment?

Posted by Scott C <iframe src='https://members5.boardhost.com/impalass427/info/user=Biscayne+Stocker' width='330' height='300' border=0 style='border:none;'> on 4/17/2018, 8:36 pm, in reply to "Brake Problem 10 Years, Never Solved! - Clevis Adjustment?"

You have the wrong bore size master cylinder. When you go to Disc front and rear you have to go to a smaller bore size master cylinder. Esp with the willwood calipers. Sounds like you need a 1 inch or 7/8 bore master cylinder.

Re: Brake Problem 10 Years, Never Solved! - Clevis Adjustment?

Posted by Dave Plummer <iframe src='https://members5.boardhost.com/impalass427/info/user=davepl' width='330' height='300' border=0 style='border:none;'> on 4/18/2018, 9:59 am, in reply to "Re: Brake Problem 10 Years, Never Solved! - Clevis Adjustment?"

You assume incorrectly I'm afraid, I ordered the right size, and Willwood agrees.

I went to a smaller bore master to give more assist at the cost of most travel.

So I'd agree except...

Re: Brake Problem 10 Years, Never Solved! - Clevis Adjustment?

Posted by Dave Plummer <iframe src='https://members5.boardhost.com/impalass427/info/user=davepl' width='330' height='300' border=0 style='border:none;'> on 4/16/2018, 8:41 pm, in reply to "Brake Problem 10 Years, Never Solved! - Clevis Adjustment?"

I haven't bugged Willwood yet, since the problem preceded their hardware...

I thought of a new way to describe it: if you set a glass of water on the console, you couldn't spill it with a single kick to the brake pedal. Any normal car, you could.

Press and hold and the brakes work, just not quickly.

Re: Brake Problem 10 Years, Never Solved! - Clevis Adjustment?

Posted by Bill H <iframe src='https://members5.boardhost.com/impalass427/info/user=speedhink36' width='330' height='300' border=0 style='border:none;'> on 4/17/2018, 9:29 am, in reply to "Re: Brake Problem 10 Years, Never Solved! - Clevis Adjustment?"

Dave,

Talk to Willwood anyway. You never know what might be resolved...they are brake experts.

Bill

Re: Brake Problem 10 Years, Never Solved! - Clevis Adjustment?

Posted by Bill H <iframe src='https://members5.boardhost.com/impalass427/info/user=speedhink36' width='330' height='300' border=0 style='border:none;'> on 4/16/2018, 3:21 pm, in reply to "Brake Problem 10 Years, Never Solved! - Clevis Adjustment?"

Dave,

I notice that you have gotten only one response so far. My first 'reaction' is: did you talk to Willwood...did they give you any input? Can we go from there?

Bill

Re: Brake Problem 10 Years, Never Solved! - Clevis Adjustment?pp

Posted by Chevy66 <iframe src='https://members5.boardhost.com/impalass427/info/user=chevy66' width='330' height='300' border=0 style='border:none;'> on 4/13/2018, 6:19 pm, in reply to "Brake Problem 10 Years, Never Solved! - Clevis Adjustment?"

I added disc to me 66 caprice .i used factory 69/70 single piston and still have drum on the rear . Now your problem I would check the vacuum that you have . When I added the power booster I found that there are two holes on the brake arm and the rod from the booster had to be installed in the lower hole . When I added the booster I added a dual marker cylinder and split the system . One more thing a high lift cam will affect the vacuum your engine puts out .some people put on a engine driven vacuum booster Good look .

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