Re: speaking of power brake boosters

[farna@xxxxxxx]

Boosters can be used from just about anything. It's just a big vacuum servo. Diameter means something, as well as number of diapragms. The think looking ones (about 4" thick) are single diaphragm, the thicker ones (6"-7") are dual diaphragm. Singles are 8"-10" in diameter, duals 6"-8". All power disc brake systems that I know of use dual diaphragm boosters. Drums use either -- bigger cars usually use a dual if they can't get a large diameter booster in. I've never seen a dual larger than 9", and they are rare (think full size late 60s/early 70s Caddys). You can use a single diaphragm in place of a dual, you just won't have as much boost. I've used a drum single with disc brakes. You don't have as much boost as you would with drum brakes, but definitely better than manual brakes! 

There are really only two things you need to worry about -- the rod that mounts to the pedal and the rod that goes into the master cylinder. I'm running an early 90s Ford Ranger 8" (I think) dual diaphragm booster now. To avoid a problem with the booster to MC rod I used the Ranger MC as well. You have to match the bore of the MC to the one you're replacing -- has to be very close if you can't get exact. More than 1/16" difference in bore is to much, and 1/16" is probably pushing it. Instead of using adapters I change the lines from the MC to the junction block. Modern MCs use standard line connections, the older ones (especially early 60s) used odd sizes to prevent mixing up the lines. The connection are also on the opposite side as the Rambler (63 Classic) MC, so replacing the lines helped that as well. 

Because the early Ramblers used a bellcrank on an up-and-away mount (moves the booster up and away from the firewall) I had to modify the rod going into the booster. I had to cut it off and weld an end to it. I took both boosters off and discovered that they had about the same stroke. So all I had to do was make the longer rod match the shorter one. I did this without taking the booster apart to remove the rod. I just had to be careful welding not to get it to hot and melt any seals. A wet rag around the rod where it enters the booster helped a lot! 

To mount the booster to the Rambler mounting brackets required shortening the studs on the Ranger booster and drilling a couple new holes in the brackets. After that it was a bolt in job. 

If you want to retain a factory style booster there are many sources. www.mpbrakes.com is one. The Jeep CJ and full size Ford (through mid 70s) boosters and MCs will work as long as you match the bore of the MC (Ford used Bendix MCs just like AMC, and they will usually bolt up except for fitting sizes) to what you're replacing. You may have to modify the length of the pedal to booster rod. 

One more thing, because of liability issues MP Brakes may not sell you a Jeep or Ford booster to put on your AMC. But they sell universal fit boosters and MCs. If you have the bracket and just need to replace a booster get the universal booster. You might have to get a MC to match, but you can tell them what bore MC and brake combo (all drum, disc/drum, all disc) you're running, and they have MCs with connections on either side. 

It's only if you need the bracket that you have to lie and tell them you have a Jeep or Ford. The Jeep bracket must be flipped to work, as CJs movethe booster down instead of up. Their liability is limited to replacing a faulty product, so I don't really see the point of not selling you a part you want. If it's the wrong thing it's your fault, as long as it worked as designed. 

On May 18, 2005 Tom Jennings wrote:

> On Tue, 17 May 2005, Armand Eshleman wrote:
> 
> > I have been looking for a booster for my 70 Javelin for a while now. NAPA
> > says they can't get one anymore. I'm not too excited about shipping the only
> > one I have to a rebuilder. I fear I may never see it again.
> > What do you guys think? Do you know of any sources for boosters? How about a
> > booster that could be fitted in place of the original. Any one tried this on
> > a 70 Javelin.
> 
> I wonder who makes the damned things... Bendix or other parts
> house?  They don't look very different, model to model, something
> must interchange.
> 
> 
> 
> 
> 
> 
> .


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