Brake booster sizing

[swampedout]

Hey folks,

I've bought 2 brake boosters for my '84 250. I should have read the door card more closely because my GVWR is over 8500 (its rated 8600). My question, before I order my 3rd booster is if anyone knows if the studs where the master cylinder mounts the brake booster on the Over 8500 GVWR booster are wider apart than the Under 8500 booster?

Thanks

[swampedout]

And follow-up question:
Rockauto has the ACDelco reman booster. Would anyone recommend this product or should I search around some more?

[Gary Lewis]

According to my post here in the Hydroboost Brake Conversion thread:

So, it looks to me that up through 1986, inclusive, the master cylinders for trucks up to 8500#'s had the narrow bolt spacing and trucks above that had the wide spacing.  But some time, probably in '87, the break point changed such that even up to and including F350's had the narrow spacing.

You didn't say what the problem has been for the first two boosters you bought.  But, does the above answer your question?

As for AC/Delco, I think their stuff is good, and I'd buy one if it was an option.

[swampedout]

Thanks Gary, that answers my question.
The problem with the first two was that the studs did not match up with the master cylinder. At first, I assumed it was another bad autozone part but it turns out I requested the wrong part. None of the brick-n-mortar parts stores carry the 8500+ booster apparently.

[swampedout]

so the 8500+ booster and master cylinder have studs set wider apart.
Rockauto had a delay on the ACdelco units so I picked up a junkyard booster which surprise does not hold vacuum. I can hear it hissing in the cab when the pedal is depressed. So now I order and wait.

[swampedout]

Scratch that. Apparently Rockauto doesny have any 8500+ boosters.
Anyone know where I can find a reman unit before I go back to the junkyards?
Thanks

[swampedout]

For some reason, the parts stores all have Boosters for 1984 F350s. According to what I think I learned from the hydroboost conversion thread, these should match up with a 1984 F250 MC with a GVWR of 8500+ but I don't understand why the catalogues wouldnt list my truck as compatible.
I hate being a nervous nancy about this stuff but I am talking about buying my 4th booster so I want to make sure I get it right.

[Gary Lewis]

If you look at our page here: Documentation/Driveline/Brakes and then the Master Cylinders & Boosters tab and then the Part Numbers tab you'll find the table below, which shows that an 84-86 F250 above 8500 GVWR takes E4TZ 2005-B.  And if you look a bit farther down you'll see that an 84 - 86 F350 also takes E4TZ 2005-B.

So, in my book the only catalog that counts, Ford's Master Parts Catalog, says it is compatible.  

[swampedout]

Gary you are a blessing!

Its still a hard item to find but I might have luck with the "F350" part.

[Gary Lewis]

Good luck!

[swampedout]

http://bronco.zenseeker.net/Brakes.htm 

Another brake sizing resource I stumbled across.
I cant verify any of this info but lots of charts stating different sizes over the years for ford and even some info on crossover with chevy sizing

[Gary Lewis]

Looks like a good resource.  

[swampedout]

Just in case anyone is looking at this for future reference:
I was able to locate a reman unit for an 84 F350 which fits. Why this part was not cross listed for the F250 is beyond me.

[Gary Lewis]

[Danny G]

Were there options with the master cylinder preattached to the booster or was everything across the board out? I know it may be a bit more money but it may be a last resort for someone at some point.

[85lebaront2]

Where it gets interesting is there were essentially two F250s, a light duty (under 8500 GVWR) and a heavy duty (over 8500 GVWR) the brakes and emission requirements change at 8500 GVWR as these are Federal Motor Vehicle Standards for the requirements. The Peoples Republik of Kalifornia has different emission standards which is why some engine options were either different or not available there.

[Gary Lewis]

TheScatch wrote

Were there options with the master cylinder preattached to the booster or was everything across the board out? I know it may be a bit more money but it may be a last resort for someone at some point.

I've never seen pre-attached masters and boosters.  I've only seen individual masters and then boosters.  Sorry.