brake proportioning block leak

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Dec 5, 2012 | 11:14 AM

mikeinganges

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brake proportioning block leak

Hello, Forum - My vehicle is an 1989 Aerostar, EB extended with a non-RBS or non-ABS brake system. Also, my braking is system is stock; no special pads or performance parts.

Problem - My brake metering/proportional block has developed a leak at the nut between the two input lines on the top of the unit.

I've been calling around and there doesn't seem to be a replacement part available up here in Canada. Before I try reefing on that nut or taking it apart (can't find any non-antilock information on it in my Ford manual) can anyone shed some light on this gizmo. Perhaps someone with a 1988 or earlier Ford shop manual has a section covering this part. I've read some of the posts, but they refer to the antilock system not my old standard type.

Thanks, Mike

Dec 5, 2012 | 06:24 PM

xlt4wd90

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From: SoCal

I'm just guessing here, but is that "nut" actually a plug of some sort? Can you pull it off and try putting some teflon tape around it?

Dec 6, 2012 | 01:01 AM

96_4wdr

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From: Washington state

get a junkeyard dog. in fact, pick up three, should be enough good parts to make one operational.

internal diagram of similar unit. NOT exact Aero

Dec 6, 2012 | 10:34 AM

mikeinganges

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Hello, forum - Thanks for your quick replies and diagram - you guys are great. I've managed to find a NOS part from Green Sales in Cincinnati, OH and it's getting FedEx'd up here quickly.

Great suggestions - But, I would hesitant to use a junker replacement part for my brake system, it could fail sooner then later and need another one. Teflon tape could work for a temporary fix, but, I wouldn't want to depend on it for long. I drive in and out the mountains up here, so, I'm very safety conscious about my brakes.

I've noticed this part has been a common failure because of internal corrosion over 20+ years operation on our Aeros. I was considering eliminating the part and just hooking up a adjustable valve on the rear line, but it'll be nice to R/R the part and maintain the designed safety feature.

Cheers, Mike

Dec 6, 2012 | 06:32 PM

xlt4wd90

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From: SoCal

Due to the high center of gravity, most trucks undergo a lot of weight shift during braking, so they all need some kind of dynamic pressure reducer (or ABS) to keep the rear brakes from locking up. An adjustable pressure regulator would have to be set to very low pressure to reduce the chance of locking up the rear brakes under hard stops. But that means they'll be less effective under less-hard stopping conditions.

Dec 7, 2012 | 05:17 AM

96_4wdr

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From: Washington state

my Aero is unsafe to drive without the RABSII working correctly.
lots of rear wheel lockup, tire skidding and sliding to the side.

hard emergency braking with the RABSII working is impressive for a 4000 lb+ rig even in heavy rain.