Some more info and pictures -- Blue85, I assume you don't mind. I had some hassles getting all of my parts sorted through, so I thought I'd share the results of my research in a "Everything you never wanted to know about hydroboost but were afraid to ask" post.
Note that most of these pics come from Oreilly, not that you necessarily have to buy from them but they're widespread, as opposed to local. Their web page also has pretty good information, so you can plug the part #'s right in there for year usage, or use the part #'s for crossreference elsewhere.
So, first, let's look at the typical 70's cast iron vacuum-booster master cylinder:
The large chamber for the front brakes is to the left, or front of the vehicle. It has a 1/2" fitting and uses 3/16" line.
The smaller chamber for the rear brakes is to the right, or rear of the vehicle. It has a 9/16" fitting and uses 1/4" line.
Now let's look at a typical 80's plastic-reservoir vacuum-booster master cylinder:
Notice that while the chambers are the same -- the larger one for the front brakes is still up front -- the fittings are reversed in size.
Compare these to a typical cast iron hydroboost master:
The smaller chamber for the rear brakes is now to the left, the front of the vehicle. This has a 9/16" fitting and uses 1/4" line.
The larger chamber for the front brakes is now to the right, the rear of the vehicle. This has a 1/2" fitting and uses 3/16" line.
The net result of this is that, when converting to hydroboost, you must pay attention to how your existing brakes are plumbed. You can identify which lines are front and rear by noting that the larger reservoir chamber is for the front brakes, and the smaller one for the rear.
You can also double-check this by following the lines down to the combination valve.
Depending on the year of your truck and how it is plumbed, you may need to swap the lines front-to-back. I found it easier to do this once I'd unsnapped one or two brackets holding the lines together as they went down to the valve. Switch the lines, then snap the brackets back.
You may also find that your existing lines don't fit. I think this would occur if you had one of the plastic style masters, as above, and were switching to the hydroboosted master as pictured. Rather than cutting and reflaring the ends (and finding the goofy-sized fittings), there are conversion fittings to do this as a bolt-on. Edelmann 258307 bumps the 1/2" up to 9/16", and 258306 reduces the 9/16" to 1/2". (I found another thread here on CK5 that says " Weatherhead part numbers 7912 and 7913 are similar, only in brass".)
More to come.
-- A
Note that most of these pics come from Oreilly, not that you necessarily have to buy from them but they're widespread, as opposed to local. Their web page also has pretty good information, so you can plug the part #'s right in there for year usage, or use the part #'s for crossreference elsewhere.
So, first, let's look at the typical 70's cast iron vacuum-booster master cylinder:
The large chamber for the front brakes is to the left, or front of the vehicle. It has a 1/2" fitting and uses 3/16" line.
The smaller chamber for the rear brakes is to the right, or rear of the vehicle. It has a 9/16" fitting and uses 1/4" line.
Now let's look at a typical 80's plastic-reservoir vacuum-booster master cylinder:
Notice that while the chambers are the same -- the larger one for the front brakes is still up front -- the fittings are reversed in size.
Compare these to a typical cast iron hydroboost master:
The smaller chamber for the rear brakes is now to the left, the front of the vehicle. This has a 9/16" fitting and uses 1/4" line.
The larger chamber for the front brakes is now to the right, the rear of the vehicle. This has a 1/2" fitting and uses 3/16" line.
The net result of this is that, when converting to hydroboost, you must pay attention to how your existing brakes are plumbed. You can identify which lines are front and rear by noting that the larger reservoir chamber is for the front brakes, and the smaller one for the rear.
You can also double-check this by following the lines down to the combination valve.
Depending on the year of your truck and how it is plumbed, you may need to swap the lines front-to-back. I found it easier to do this once I'd unsnapped one or two brackets holding the lines together as they went down to the valve. Switch the lines, then snap the brackets back.
You may also find that your existing lines don't fit. I think this would occur if you had one of the plastic style masters, as above, and were switching to the hydroboosted master as pictured. Rather than cutting and reflaring the ends (and finding the goofy-sized fittings), there are conversion fittings to do this as a bolt-on. Edelmann 258307 bumps the 1/2" up to 9/16", and 258306 reduces the 9/16" to 1/2". (I found another thread here on CK5 that says " Weatherhead part numbers 7912 and 7913 are similar, only in brass".)
More to come.
-- A
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..putting the lines back where they belonged using adapter fittings fixed that problem..
Well Done!
