J50 Brake Option for 1965 - Issue with No Brake Peddle Travel
Hi. We are working on restoring a 65 vette that is currently equipped with the J50 brake option (power 4-wheel disc). Not sure if this car originally had the option or if it was added. When the car arrived, it did have stopping power, but there was maybe 1/4-1/2 of travel on the peddle before it hit the floor! We are stumped on why there is no additional peddle travel (basically, why the peddle is not sitting higher off the floor). Here is what has been done so far: the calipers are all new, the lines have been bled and no kinks, the master cylinder is the correct part number for J50 and has been rebuilt, bleeders are ok, and the brake booster appears to be in good condition. However, the booster does appear to be a replacement with no part numbers. Where the brake boosters for 1964-1966 all different (did they have different length rods)? Maybe if the wrong brake booster was installed, it caused the short peddle travel?? Any thoughts would be helpful. Thank you!
-
-
Re: J50 Brake Option for 1965 - Issue with No Brake Peddle Travel
Nick,
The rod from the booster to MC is adjustable to remove the travel. Consult the service manual for proper adjustment. If you don't have one you can purchase one from the NCRS Services.
JR -
Re: J50 Brake Option for 1965 - Issue with No Brake Peddle Travel
Nick - I think Ray has a good suggestion there, check the rod from the brake pedal. My neighbor has a 66 L72 with J56 power brakes and he was complaining about how low the pedal was and it turned out that with all the work done on the car, the adjustable rod was not extended enough.
The pic below is how we found the brake pedal.
DSCN2123.jpgMike T. - Prescott AZ.Comment
-
Re: J50 Brake Option for 1965 - Issue with No Brake Peddle Travel
thanks guys for the input. it appears the rod on this booster is not adjustable...it must be an aftermarket. someone else had mentioned that if the car does not have a proportioning valve on the brake lines it is difficult to get a high peddle...we are exploring that option before switching the booster.Comment
-
Re: J50 Brake Option for 1965 - Issue with No Brake Peddle Travel
Nick - Not sure if this exploded diagram will show enough detail but there should be a captivated pin that holds the clevis to the brake pedal arm and the pushrod is threaded into it and adjustable for length. Any chance you could show us a pic of what is on that 65?
Mike T. - Prescott AZ.Comment
-
Re: J50 Brake Option for 1965 - Issue with No Brake Peddle Travel
You need a...
1963 Corvette Shop Manual
1965 Corvette Shop Manual Supplement.
1965 Corvette Assembly Instruction Manual (AIM)
1965 Corvette Vehicle Information Package - a free download from the GM Heritage Web site.
If you have a 396... 1965 Chevrolet Interim Shop Manual (It has all the 396 service info)
I'm not sure about '65, but J-50 may use a different hole on the pedal arm to attach the pushrod. The J-50 section of the AIM will tell you, and I recommend that you cease work until you have procured the above documents.
DukeComment
-
Re: J50 Brake Option for 1965 - Issue with No Brake Peddle Travel
yes, we did look at the fine adjustment on the push rod/clevis which is used to make sure the pedal has the correct contact with the stop light switch. It doesnt seem like there is much left to adjust at this location. a proportioning valve has been ordered and should be installed by next week to see if that makes any difference. i'll provide an update at that time. thanks!Comment
-
Re: J50 Brake Option for 1965 - Issue with No Brake Peddle Travel
The '65 J-50 disk brake system did NOT have a proportioning valve, just a pressure differential switch. So how do you think adding one will solve your claimed pedal height issue? I've lost track of how many Micky Mouse bubba fixes I've helped vintage Corvette owners identify and correct over the years.
I'll give you the same advice I give everyone else. Get it back to serviceable OE configuration and I'll help you out (sometimes hands on for local guys) IF and only IF you currently have or procure all the documentation that's required.
In the last couple of months I've sorted out and corrected serious distributor and carburetor issues on a '65 L-78, and a heater/defroster control cable issue on a '67 L-71 that might have caused a significant point loss during Ops Check next month at the national convention in Palm Springs that may have cost the owner his objective of a 99 percent Top Flight.
They either had the necessary docs or procured them before I was willing to lay a hand on their cars, and in each case after we slayed the dragons they realized that we would have been lost without them.
Good luck with your project.
DukeComment
Comment