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-   68-69 GTO Tempest & LeMans TECH (https://forums.maxperformanceinc.com/forums/forumdisplay.php?f=433)
-   -   Disc brakes (https://forums.maxperformanceinc.com/forums/showthread.php?t=737859)

knauert1 09-26-2013 08:16 AM

Disc brakes
 
I installed Wilwood disc brakes on all 4 corners of my '68 GTO Vert a few years back and love(d) it. I recently finished m '56 F100 with Wilwood brakes as well and it seems to stop better. In the GTO it seems that you have to push harder down on the brake pedal almost like they are power assist brakes not power brakes. It seems to be virtually the same set up on both vehicles. Could it be that I don't have enough vacuum in GTO?, I do not fully understand how it all works.
Thanks,
Tom

68gtoMN 09-26-2013 11:24 AM

Yes, check vacuum source/amount. What type of camshaft are you running? If yours is an aftermarket model with large overlap or duration, you will have less vacuum and that WILL make the pedal less responsive. If this proves to be true, you CAN improve that situation with an aftermarket vacuum canister.

You can check your vacuum with a gauge. how many inches of vacuum do you pull at idle?

Ozzmann 09-26-2013 08:25 PM

I have the same problem and am looking at fitting a hydro boost to replace my vacuum booster.

knauert1 09-26-2013 08:59 PM

My plan is to work on the car this weekend. How much pressure should I have? Can you suggest an after market vacuum canister?
Thanks,
Tom

knauert1 09-26-2013 09:01 PM

Ozzman, what brand/model hydro boost did you get?
Tom

68gtoMN 09-27-2013 11:10 AM

There are many. Mr. Gasket has one - here's an example
http://www.jegs.com/i/Mr.+Gasket/720...FXBo7AodMzwABQ

I have not checked to see if our host offers such a part yet - perhaps searching here would be a good first step.

As for vacuum signal you "should have", I can't answer without knowing specifics about your engine combination. My car was running about 17" of vacuum and my factory disc brakes worked fabulously.

knauert1 09-28-2013 09:56 AM

Vacuum
 
I have the stock 400 motor that was freshened up but swapped cams with the original cam that was specked with the Judge motor. its been some time since I looked closely at how everything is plumbed but is my existing "coffee can" vacuum reserve tank that is used to store vacuum for headlights effected at all?

68gtoMN 09-28-2013 03:13 PM

You might also need to look at your proportioning valve. Do you have too much bias toward rear? Brake feel, if hard pedal, could be due to proportioning and not vacuum. If you're running a factory spec cam, I see no issue with brake vacuum. Headlight vacuum canister should not be affected.


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