MC Pushrod Material question???

[SHANE 73Z]

Hey guys,

I just received my new master cylinder. I need to piece together a linkage for it and was wondering your opinions.

My current plan includes a 3/8"-24 Female rod end (from McMaster) for the pedal side. The MC/Bias Bar assembly has a 3/8" (roughly) ID tube for the pushrod to seat in. My question is would a 3/8" (actually 13/32") 6061-T6 rod be safe to operate the brakes. McMaster offers rods with the ends already threaded for rod ends but the 3/8" (and larger) sizes are made of 6061-T6. 5/16" and smaller are mild steel.

I am guessing the rod length (not including the rod end) will be about 6" maximum.



Thanks in advance,
Shane

[David Pozzi]

I would not do that. I'd buy a fine threaded grade 8 bolt and cut it to length. Brakes are too important to trust aluminum, it does not have nearly the fatigue or bending strength.

[SHANE 73Z]

Hey David,

Thanks for the advice. A friend of mine actually volunteered to make me one out 1045 steel.

An off topic question. I remember on your wifes second gen that you were running into MC troubles. On my car there are 2 holes in the pedal. The upper one has a bracket bolted to it, to actuate the brake light switch and the lower runs the rod to the booster. With the manual setup on her car which hole did you use for the MC pushrod????

Thanks for all of your help,
Shane

[David Pozzi]

I used the upper hole for manual brakes. I was told on the second gen forum that the later Trans Ams have a manual hole that is just a little higher up on the pedal. I forget the exact amount but maybe 3/8" higher. This would help ease the pedal effort but I am going to just put a new booster on the car and get it going.

I'm running out of time fooling with the brakes on this car and have a lot of other things to do to it. If I'd kept at it, I'd have tired either a smaller bore master cyl or drilled the upper hole higher.