I am having a hard time finding any numbers on the brake booster on the winter charger. It does not seem to be doing it's job and will not hold a vacuum ( check valve is ok ). Also, the brakes seem to be functional as far as the hydraulic portion (bled, good hoses/lines, etc), but the assist is not there. The car was already converted to 11.75" brakes when we got it so I am not sure of where the donor parts came from. I will need to get some #'s to order a rebuild kit or a replacement. At this point the brakes take enough effort that I am not confident that the master cylinder has enough travel. The pedal seems pretty low to the floor.

I have never rebuilt a brake booster before but assume there is not much to it? Any feedback on my optimistic thoughts here?

Sorry for the ramble but I'm kind of new to the power brake system.

Thats a Midland Ross single piston. Same as on my 65 Satellite.
Contact Wayne Brown at
wayne@theramman.com

That booster is available at most any auto parts store for $125 or less.

BUT – if the car has been converted to discs do NOT use that drum-brake booster with them. It will feel OK for normal driving but will not provide enough assist for a panic stop. Discs require higher hyd pressure than drums, due to lack of servo action and . Other people might argue a drum booster is fine, but the factory engineers used different boosters between drum and disc, so contemplate why they did that. Maybe they knew a little more than most of us do.

Anyway, a bad booster typically gives a HARD pedal, not a LOW pedal. If the pedal is low, something in the pedal-booster-MC geometry is amiss.

Thank you for your insight. I was looking at part numbers on rockauto the other day and noticed that the drum-drum boosters seem to use a different part number than disc-drum. The way you described my symptom is dead-on. The car will stop ok but it seems to take lots of pedal effort to get it to stop fast. The pedal might right where it should be from the factory, I am not familiar with power brake cars of this era. Also, before finding a different booster I would like to verify what I currently have.

If I wanted to swap to a disc-drum booster what year/model would I ask for at the parts store?

Thank you!

In my C-body experience, MB pedals are usually 1-2" higher/closer to your feet than for PB (different pedal and bracketry under the dash). Some other cars had the same pedal setups but different brackets underhood. the extra pedal travel for MB must be created somewhere/somehow.

The 66-70 dual-diaphragm disc boosters (which look similar to the 'Hemi' booster) have becme unobtainable. 'theramman' linked to earlier usually has some ebay auctions that provide good info and pics.

The one I suggest you look at is from 71-?, it's a larger diameter which gives the extra boost, and it's pretty cheap and seems to be readily available -- but it may not fit in every car (it interferes with the column linkage in a C-body, for example).

You could also look at other Mopar disc cars and see what boosters are avaialble.

Thank you Mark and Fury Fan for your help. I am going to swing by the salvage yard and have a look today.

Am I the only person to have this problem?

I sure wish I could find an easy answer as far as what booster will bolt in that doesn't cost five hundred dollars. I will make sure to take lots of pictures at the junk yard so we can get to the bottom of this. I re-read the Mopar Action disc brake swap article and they do not mention the booster at all.

As I re-review the pic you posted earlier, it looks like a tight fit between the inner apron structure and the booster. I'm not sure the 71+ large-dia, single-diaphragm booster I mentioned earlier would fit.

You might need a smaller-dia dual-diaphragm booster. I **think** some of them are still available, they have a more rounded appearance than the Bendix 'Hemi-style' booster.

Don't forget to check Master Power brakes and such for a generic-fitment booster if you exhaust other options.

So far, from all of the pictures I have seen they are painted. I was going to order one today but decided not to because a very generous member contacted me concerning a '69 disc unit for sale. I will follow up once I complete the swap.

I separated the master cylinder from the booster today and found that the master is leaking from the bore a little. It looks like it has been for some time. I ordered a replacement (application was a 1976 Plymouth Valiant with power disc brakes) and will re-bleed the system when I swap it. I also adjusted out the pushrod in the brake booster assy to just barely make contact with the plunger on the master cylinder and that helped a bunch.