I am slowly working my way through a disc brake, power steering, automatic transmission swap from a 1978 F150 to my 1966 F100. It has gone pretty smoothly. I swapped over the whole front end and installed rebuilt calipers, new brake hoses and dual chamber master cylinder.
I studied both truck's brake pedal assemblies and I decided the best way to go was with the 66 config. Since the clutch pedal is the master shaft for the brake pedal, I remover the clutch pedal arm where it attaches to the shaft and the ball crank on the other end of the clutch pedal shaft with only the original brake pedal hanging down. I bled the system last night and ended up with a real solid feel when the brakes are pressed. However, when you let off the brakes, the pedal seems floppy and loose as if it should have a return spring to bring it to the rest position. I am probably several weeks from having the engine, transmission and steering column back together, so I can't get a real good sense of what it will feel like on the road. Is it possible that the push rod for the master cylinder is too short? I had to use the 66 push rod as the one that was supplied with the new master cylinder was several inches too long.
This whole problem probably doesn't make a bit of sense unless you have done this swap yourself. I'm hoping one of you can point me in the right direction. Should I have adapted the 1978 pedal assembly? Is there an optional push rod to try? I'm pretty sure adding a return spring to the brake pedal is NOT what I need to do. Thanks in advance.

 

Sounds like your swap is close to mine. I went from 3 on the tree to C6 auto. I dropped the clutch pedal and kept the brake. I had to drill a new hole about 1 1/8" towards the firewall to drop the angle of the pedal. I understand some have used a block on the firewall to achieve the same.

I am not sure the cause of your issue, but am wondering if it is connected to not having vacuum on the booster.



John

 

Are you doing a manual disc swap or power disc?

 

I'm using the manual brake setup that my donor was equipped with. I never considered the brakes to take a lot of pedal force. I am looking forward to the power steering and the C6. John, I'm not following your need to drill a new hole....Did you have an alignment issue?
The pushrod is attached to the brake pedal with a special bolt with a large diameter that goes through the eyelet on the pushrod. Between my 66 and the donor, on one of them the enlarged diameter was manufactured as an ecentric. Depending on where you lock it down it gives you a varied stroke length. I've been searching through archived posts and found others mention that the original pushrod is too short and the replacement that comes with the new master cyl to be too long. It almost seems like I could trim down the longer pushrod. I'd just have to do a little creative grinding to reshape the rounded tip.

 

What John was referring to drilling is the pushrod on the power booster which does not apply since you are doing manual discs. I think this write up will help you:

f100discs

 

Sorry bub, when I read "disc brake, power steering, automatic transmission swap" I presumed it was power disc.

My bad, standing down.





John

 

You weren't bad (at least in this case ), so...don't be too quick to stand down Mr. Wilkerson, because...

Something is amiss in post #1. The OP said he got the parts from an 1978 F150

1973/79 F100 = Manual disc brakes were standard equipment, power disc brakes were optional.

ALL 1975/79 F150's have power disc brakes as standard equipment!

I'm assuming both the 1966 and 1978 are 2WD, cuz disc brakes weren't available w/4WD until 1976 and they're power.

I noticed this discrepancy 2 days ago, but didn't chime in...until now.

 

"I'm assuming both the 1966 and 1974 are 2WD, cuz disc brakes weren't available w/4WD until 1976 and they're power."
Where the heck did a 1974 anything show up in previous posts?

 

1974 shoulda been 1978...since corrected.

 

Thanks for the replies. 66f-100, I had already read that article. It is a good read and I have been back to it a few times. It gave me inspiration to take another look at the problem last night. I realized the original push rod was only about half an ich too short. I took the too long rod that came with the dual master cyl and measured off where I wanted to be. It was perfectly in line with a second diameter flare from the master cyl. end. I cut off the excess and carefully recreated the rounded tip with the bench grinder. I sat down by a toasty fire in the wood stove, a winter ale, my ever present barn kitty and a couple of grades of emory cloth. In no time I had the tip polished smoothly. I put it back in the truck and with the ecentric mounting bolt I dialed in the pedal heighth. It made a complete difference in how the pedal feels. Unfortunately, when I read through the swap article I noticed the advice to retain the original front coil springs. I'm gonna have to go swap those back in. This project has gone pretty smoothly, but I do find myself working from both ends to the middle only to find I've miscalculated something that needs to be reworked. It gives me a lot of appreciation for the guys on this forum that fabricate at will.