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you have to make the rod it was posted earlier. there is about 3/4" difference between the too. take a few pics and post them when you do this if you can so everyone can see how it is supposed to be. doesn't sound too hard to do but it is hard for me to picture without the stuff in front of me.
ok unbolt your master from your factory brake booster and a pushrod about 2 inches long will come out. It has nothing to do with the rod that bolts to your brake pedal although that does need lengthened due to the shorter rod on the HB unit. Your getting them confused they are two differnet things.
no I know what you are saying. The rod for the hb to the master is the same but you need to machine the ID on the hb to fit the master or use a 4th gen master which is supposed to be a direct fit. the rod to the brake pedal needs modded to work.
- a hydraulic brake boost unit out of a 94 GMC Safari (equivalent to Astro)
- a new steering box (IROC quick ratio)
- 16mm and 18mm x 1.5 steel o-ring to -6AN adapter fittings from KRC Power Steering (for the steering gear box and the boost unit)
- 4th gen LS1 master cylinder
- sawn-off pedal rod from the original vacuum boost unit
A few weeks ago I put some paint on the steering gear box and the hydroboost and installed the -6AN adapter fittings. I just wanted to make sure that I have more/less everything necessary to install this. I was planning on welding in some 3/8" all-thread on the pedal side of the hydroboost, then threading the original pedal rod. A coupler could then be adjusted for the right amount of "jiggle" on the brake pedal. Are there any other tricks to this setup?
I can take some pictures of the parts, and as much of the process I go through right now. The engine compartment is completely stripped for fresh paint (no engine, tranny, etc). I won't be putting on the master cylinder or testing the brakes for quite some time. I'll try to get some photos of hooking up the pedal rod. It is a tough spot to take pictures, that's for sure.
What has to be modified on the 3rd gen master to make it work..?
Does the OD or the length of the master cyl. part that fits into the HB need to be reduced (by 0.050" per previous post).
I plan on doing a C4HD brake swap and wad told that I must run a disk/drum 3rd gen master.
Mine is complete and looks great. I will be bolting on my heads, intake and turbos next week and have a new steering box from red head on its way and should be able to drive it next week sometime.
I went with the 4th gen master because it cleans up the engine bay and I like the cap design it actualy seals shut. You can use the 3rd gen master you just need to shave off the material on the OD so it will slide into the HB. The lenghth of the 3rd gen master is fine.
This realy is an easy mod. The rod on the back of the HB is about an inch short. I just cut it of and put an adustable jam nut and welded the old pedal end on my HB.
I want to do this mod especially since my power steering fluid is leaking. but Im aprehensive about shortening the rod. I'm not good at welding.
I have V-belts if I use the astro pump is it possible to swap out the pully?
I don't have access to a third gen master cylinder, but my fourth gen unit has an OD of 1.469" or 1-15/32" for that bore in the back, if you're interested in modifying your existing third gen unit.
I took some pictures of the parts I'm using for this mod:
- hydroboost unit, with a fresh coat of paint and the KRC adapter fittings
- brake pedal rod from third gen vacuum booster
- vacuum brake booster bracket
ok so no one has comfirmed the the 4th gen does bolt right up. superirocz, does it? so what you need to do once removing the old is...
1.bolt on the old vaccum booster bracket
2.bolt on the astro HB
3.bolt on a 4th gen master cyl
4.plumb it up
5.and shorten the pedal rod under the dash
here is my pump and the rod looks like it could work without changing anything. I am going to try and get it mounted without messing with the rod. Looks like it may be done.
the 4th gen will bolt up but it must be a 98+/ls-1 4th gen. I got my car running but have not driven it down the road yet. In my driveway the HB seems to be working great.
it looks just like mine was. You will need to shorten it about an inch but take measurements to be exact. What I did was cut most of the HB rod off and put a threaded lock nut/bolt so I have some adjustement with length and while your at it may as well weld your factory rod onto the threaded bolt so it will silde over the brade pedal. The HB rod end is much larger in diameter that the stock rod on your vacum setup.
Are 4th gen master cylinders required? I would rather use a 3rd gen one since they are $30 for a remanufactured one vs over $100. Just in case I want I ever need to replace them or decide to go with new parts.
you would have to get the hydroboost pump machined to use our master cylinders but look on ebay and a couple sponser sites and you can find a ls1 master cylinder for about $30 also.
