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 Posted: 04-28-2005 09:29 am
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Harkes
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Hi all,

whilst the engine is still not in, i have time to have a look at the brake booster. I will be replacing the old master cylinder for the TR6 new master cylinder.

I now want to check if my brake booster is performing well or not. How can one check this?

I just took the whole brake booster & peddle box out for closer inspection.

any tips what/where to look for?

erik

"The Shark" JH 15175

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 Posted: 04-28-2005 03:18 pm
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Mark Rosenbaum
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The quickest way to test the brake servo is when the car's in service.  One brakes the car from a known low speed (a) with the servo hooked up normally, and (b) with the vacuum line from the intake manifold disconnected and capped off.  For case (b) there should be a very noticeable increase in the pedal pressure required.

In your case this won't be practical for a while, obviously, so you'll have to check things out individually.

The one-way valve should snap shut whenever the pressure on the inlet side exceeds that on the servo side by a very small amount -- basically, blowing gently through a straw at its innards should be sufficient.  If necessary, the valve can be cleaned with a mild solvent.

The sealing washer for the valve should be carefully examined and replaced if worn or damaged.  Also, check for corrosion and damage around its mounting hole in the servo housing.  If necessary, a small quantity of a flexible gasket sealer such as Hylomar can be used to assist the sealing here. 

If the servo's vacuum chamber is pumped down to 20" (500mm) Hg of vacuum, it should retain at least 15" (380mm) Hg for at least 10 minutes.  Ideally it should retain the 20" of vacuum for hours or days.

If a noticeable amount of brake fluid is found inside the servo, one can expect eventual failure of the rubber parts within the mechanism, and a rebuild is desirable.  Otherwise, however, these things seem to last indefinitely. 

If you disassemble the foot pedals for cleaning and painting, I advise comparing the location of every part to the parts book drawing.  The drawing does not correctly show the correct orientation for several parts -- ISTR this includes the brake switch bracket and pedal return spring, and perhaps a couple of other items.  If your assembly is already in pieces and you need advice, I have a correctly assembled spare unit I can look at and try to describe for you, just let me know.

When attaching the lower part of the throttle pedal to the upper part, be sure to use Grade 5 or better bolts and lock nuts, and torque these down properly (2-4 ft-lb IIRC).
 

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 Posted: 04-28-2005 05:27 pm
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Brett Gibson JH5 20497
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Erik, while you have your pedal box off have a look at the weld points were the pedal arms attach to the pivoting rod, I dont know if it has ever happened to anyone else but my gas pedal broke away once, had to take the whole box out to reweld it.

Very nice looking engine by the way.

Brett.

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 Posted: 04-28-2005 06:24 pm
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Jensen Healey
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Remember, you can have the servo rebuilt for around $100 at Partco. I used them and am very satisfied.  Click tech and parts to find the info.

Kurt

Last edited on 04-28-2005 06:25 pm by Jensen Healey

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 Posted: 05-02-2005 02:42 pm
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Harkes
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Mark,

i will check the valve to see if it shuts. Over the weekend i had it out, disassembled, sanded, cleaned and painted and I reassembled it just last night. Looks as new!! I'll make a picture of it and post it on the jhppg.com.

End of last year the brake booster performed well, but to make sure i'll do the valve test. When it is good i will put back in the car and do the drive test when the engine is back in as a last test.

thanks a lot for your great help.

erik

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