Brake booster for disc/drum

rsk392 · Aug 27, 2024

Car is a '68 but fitted with stock manual 1970 front spindles, discs (single piston) and drum rears.
I had an aftermarket booster fitted for 15 years but this had no feel at all - it was like the pedal was just swinging in fresh air. The brakes were good, though.
For the last 5 years I have run it with the booster removed. Obviously the pedal pressure needed is now a lot higher, and I'd like to get something between the two.
Here in the UK there are many sellers of aftermarket small boosters for single-circuit use. I'm thinking of trying one on the fronts only - has anyone tried anything similar?
If so, would you recommend 2:1 or 3:1 boost ratio? Any downsides to this idea?
Thanks
Roger

Hemikiller · Aug 27, 2024

Another option would be to decrease the bore of the master cylinder piston, which will reduce the required pressure, but increase pedal travel.

Sheriff41 · Aug 27, 2024

You need to make sure the pushrod depths from the brake pedal into the booster, and the booster into the master cylinder are adjusted properly for the power brake setup. If these are not set correctly, your brake system will not perform as designed.

For brake boosters, I'd recommend checking with West Coast Classic Cougars https://secure.cougarpartscatalog.com/store/Search.aspx?SearchTerms=brake booster&CatID=15895 and watch their videos:

rsk392 · Aug 27, 2024

Thanks for the advice - I was thinking of using a remote booster rather than replumbing the entire system. Maybe running the remote servo on the front brakes only (68/70 is dual circuit).

canook2u · Aug 27, 2024

rsk392 said:
Car is a '68 but fitted with stock manual 1970 front spindles, discs (single piston) and drum rears.
I had an aftermarket booster fitted for 15 years but this had no feel at all - it was like the pedal was just swinging in fresh air. The brakes were good, though.
For the last 5 years I have run it with the booster removed. Obviously the pedal pressure needed is now a lot higher, and I'd like to get something between the two.
Here in the UK there are many sellers of aftermarket small boosters for single-circuit use. I'm thinking of trying one on the fronts only - has anyone tried anything similar?
If so, would you recommend 2:1 or 3:1 boost ratio? Any downsides to this idea?
Thanks
Roger

have you relocated the connection point on the brake pedal? if not, that is why your boosted brakes are so easy. manual brakes should have a 6-to-1 pedal ratio, power brakes should be 4-to-1.

rsk392 · Aug 27, 2024

The car was originally manual drum brakes all round, so the bulkhead etc. is original manual. I was trying to preserve the bulkhead in original condition, but it seems that's not a sensible option if I want to go power brakes. I hadn't realized that manual discs were not an option in '68.
So, I have an original manual brake pedal and pivot point which will give more leverage. The original kit I bought (from NPD? Can't remember) was to convert manual brakes to power - the booster was designed to work with a manual pedal, not a power one. There was no feel to it at all - even when standing the car on its nose, the pedal felt really soft. The brakes worked fine, just no feedback at all.

canook2u · Aug 28, 2024

I recently installed a power conversion to a factory manual brake '71 Mach1. The conversion re-uses the manual pedal, but the pedal has to be re-drilled 2" lower than the factory, (manual), push rod hole. this provides the proper angle for the push rod while creating a 4-to-1 pedal ratio. LESS pedal travel, but MORE, (proper), pedal feel. check to see if your push rod is at the correct angle to the pedal, my guess is that it is not.

rsk392 · Aug 28, 2024

Yes, I think that's the problem. When I fitted this kit back in 2005 (NPD), I left the manual pedal as it was. My memory's a bit hazy from that time but I'm pretty sure the kit was an un-named aftermarket booster designed to work (ish) with the manual brake parts.
I think I'll go with one of Mustang Steve's conversion kits, to do the job properly.

Brake booster for disc/drum

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