Author Topic: Brake booster adjustment  (Read 212 times)

Offline JKcuda

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Brake booster adjustment
« on: May 16, 2021 - 03:33:02 PM »
So... Long story short a few years back I put a right stuff 4 wheel power disc conversion on my 72 cuda that has manual drums. I had an issue getting the brake pedal returning far enough to hit the brake switch and turn off the brake lights. A few folks here suggested I lengthen the push rod, which after 4 years of storage I've now finally done.

My question is...is there a "correct" length?  I have it adjusted to the point where from what I can tell the pedal is now returning far enough to hit the brake switch but the brakes don't feel smooth at all. When I press the pedal there's almost what feels like a delay and then the booster kicks in and the brakes grab somewhat harshly (I can hear the air rush sound of the booster?). Is this just a keep adjusting until it feels right thing or there some kind of tool I can use to get it set correctly?  Thanks!




Offline 70chall440

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Re: Brake booster adjustment
« Reply #1 on: May 17, 2021 - 12:48:30 AM »
My first question would be why didn't you just adjust the brake light switch? There is a length but I don't remember what it is, however I guess it depends on your specific set up, you can probably adjust the rod a bit longer without too much issue but the piston in the MC only goes so far, so of you have it too long you are only flexing the firewall and MC seals.
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)

Offline JKcuda

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Re: Brake booster adjustment
« Reply #2 on: May 17, 2021 - 07:48:27 AM »
My first question would be why didn't you just adjust the brake light switch? There is a length but I don't remember what it is, however I guess it depends on your specific set up, you can probably adjust the rod a bit longer without too much issue but the piston in the MC only goes so far, so of you have it too long you are only flexing the firewall and MC seals.

I did at first, but even still the pedal wasn't returning to the proper position which was the issue.  I'd have to pull it up with my foot because at idle it would sit about 2-300 rpm's higher until I did so.  It's now acting normal but the brakes feel off.  They work fine, the pedal just isn't smooth.  I'm just trying to figure out if I should spend more time messing with this booster or just get a new one.  I've heard these right stuff boosters were junk...
« Last Edit: May 17, 2021 - 07:50:25 AM by JKcuda »

Offline 70chall440

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Re: Brake booster adjustment
« Reply #3 on: May 17, 2021 - 12:41:02 PM »
Ok cool, sounds like you might have an issue with the booster and perhaps even the MC. If it were me, I think I would replace both in one shot but it might just be the booster.
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)

Offline JKcuda

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Re: Brake booster adjustment
« Reply #4 on: May 17, 2021 - 01:49:16 PM »
Ok cool, sounds like you might have an issue with the booster and perhaps even the MC. If it were me, I think I would replace both in one shot but it might just be the booster.

Yeah that's kind of my thinking.  I rushed into this kit years ago so I could get the car on the street and am now regretting doing such.  I'll toy with it a bit more and then look at a replacement if I can't get it working I suppose.  It stops like a champ, the problem is you'll hit your teeth off the dash if you aren't ready for it haha.
« Last Edit: May 17, 2021 - 05:08:57 PM by JKcuda »

Offline 70chall440

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Re: Brake booster adjustment
« Reply #5 on: May 17, 2021 - 08:33:43 PM »
If it is stopping hard then at least you have that verses not stopping. That said, it might be possible that your MC is a bit too small.
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)