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(1) 2 »

Treadlevac booster working?
#1
Quite a regular
Quite a regular

Phil_78
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Can someone help me with a few problems i'm having? Firstly when I rebuilt my booster it came with booster assembely grease. I assumed that it was to coat the leather seal in the booster but the viscosity of it is stopping my pedal from returning. Have I made a mistake or just put too much on? Also, how is an effective way of knowing my booster is working or not? Thanks again

Posted on: 7/11 4:20
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Re: Treadlevac booster working?
#2
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BH
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Is it only application that is affected and not pedal return? If so, it could be a vacuum-related issue - anything from the engine source through the poppet valves.

Posted on: 7/11 8:28
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Re: Treadlevac booster working?
#3
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HH56
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The pedal is returned to the home position only by spring tension. With the engine off and one of the PB hoses disconnected so all the reserve vacuum is out of the system, if the pedal does not return via the spring you can be fairly sure something is misaligned or binding. It could be some mechanical issue with the carpet or pedal & bracket, the assembly lube could be sticking, or possibly the small clip that holds the upper spring retainer cup to the hydraulic piston came off and the spring is not under enough tension to push the power piston up. One poster even found his spring had been rusty and finally broke in two but a broken spring is a rare condition and not as likely as the other causes.

If all seems normal without vacuum, then hook the vacuum back up and if the problem happens there is something in the vacuum or valve mechanism that is allowing vaccum to leak into the power side and pull or hold the piston down. You did not mention a year but if it has the rubber poppet valves, one could have dried or cracked allowing a leak. If it is the first version with the spool valves or has the firewall mounted breather make sure no problems are in the hose or breather and air can get back into the unit. On canister mounted breathers make sure nothing is blocking the two holes under the air filter. Also make sure the vacuum is connecting to the proper port on the two hose units. Another possibility on either unit is a felt cushion on the cover has loosened or been installed incorrectly and the piston is not able to completely return to the up or home position to allow the valve to close. If that is the case the brake might think it is starting to be applied and a tiny bit of vacuum is getting into the power side of the booster holding it in position.

As to how you know if the booster is working, believe me you will know. With everything working properly, just a light push on the pedal with your toe will slow the car to a stop. Pushing harder as you might do in a panic stop can be enough to get you up close and personal with the steering wheel or windshield. If the booster is not working you can all but stand on the pedal and consider yourself lucky if you slow down within a reasonable distance, let alone stop. With the 1:1 pedal ratio, the amount of pressure at the wheel cylinders is not multiplied by mechanical advantage so without the booster, pressure at the brake shoes is dependent on how hard you push the pedal and a couple of hundred pounds doesn't do much.

Check out this commercial at about the 40 second spot for a demonstration of the normal brake operation. https://www.youtube.com/watch?v=eMgriMYCtNc

Posted on: 7/11 10:28
Howard
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Re: Treadlevac booster working?
#4
Quite a regular
Quite a regular

Mechagon
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Did you actually reinstall it yet? Whenever I've used the rebuild kits the shaft always seemed extremely tight in the seal but always worked fine when installed.

Posted on: 7/11 14:43
Alberta - Canada
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Re: Treadlevac booster working?
#5
Home away from home
Home away from home

PackardDon
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Could it have been put back together with the plunger on the wrong side of the compensator valve? If professionally rebuilt that’s unlikely but easy for a do-it-yourselfer to do.

Posted on: 7/11 18:49
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Re: Treadlevac booster working?
#6
Quite a regular
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Phil_78
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Thanks everyone. From your info I assume there is a leak somewhere. I did do it myself and the spring is in good condition. I replaced all poppet seals but will pull it down again and inspect. As for the pedal not returning, I’m nearly certain I used too much assembly grease and that’s making it stick. Thanks for the info, Phil

Posted on: 7/11 19:04
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Re: Treadlevac booster working?
#7
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Phil_78
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Just to confirm, I replaced all vacuum hoses to the booster and reservoir. The hose goes to a brass connection at the bottom of the carb on a (I think) 5/16 fitting. Is this correct? Not a huge amount of vacuum, thanks again, Phil

Posted on: 7/11 19:11
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Re: Treadlevac booster working?
#8
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Owen_Dyneto
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Your manifold vacuum at idle should be in the range of 18", +/- 1 or 2. Much less and your booster will loose some effectiveness.

You didn't mention a vacuum check valve at the carburetor take-off. It's very important to keep enough residual vacuum for a couple of powered brake applications after the motor is shut down.

Posted on: 7/11 19:50
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Re: Treadlevac booster working?
#9
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Quite a regular

Mechagon
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Quote:

Phil_78 wrote:
Just to confirm, I replaced all vacuum hoses to the booster and reservoir. The hose goes to a brass connection at the bottom of the carb on a (I think) 5/16 fitting. Is this correct? Not a huge amount of vacuum, thanks again, Phil


There's also an internal hose in the booster

Posted on: 7/11 20:53
Alberta - Canada
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Re: Treadlevac booster working?
#10
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Phil_78
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Yeah might change that too. Thanks

Posted on: 7/11 22:31
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(1) 2 »




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