Hydroboost your FSJ, CJ/YJ, Commando, M715, Bronco, IH, S10, C3, FJ40 for $125+, TX

[Elliott]

Usually it drops... if your steering works normal you are good to go but keep a close eye on the reservoir level at first.

[Resbum]

Hi Elliot, thanks for visiting my build thread.

I've been modifying my PS pump reservior, and if you don't mind, I may post the mods here. I think it would help people see what's going on inside the PS pump.

Resbum

[Elliott]

Just email me but, sure, you can post the stuff on here.
Thanks,
Elliott

[Resbum]

Sorry it took so long to get back to posting this info.

If anyone is considering modifying the PS pump reservoir here's some info that might help. Taking Elliott's advice about flow, all the fittings now have a larger inside diameter.

The engine on my project truck didn't have a hydroboost PS reservoir, but a friend gave me PS pump that would work. As can been seen in the picture, all the lines came out and promptly turned into the area the steering shaft needs to be. Because I'm converting to hydroboost the pressure line will not be an issue, but I needed to reroute the two return lines. I bought some #6 AN fittings and trimmed the inner parts down to clear the actual pump casting inside. Once that was done I bent and formed the tubes. Note- The orginal tubes were really restrictive through their bends.




In this picture you can see there are parts just inside the housing where the tubes return. This is why I cut down the inside parts of the AN fittings and ground the nuts down to about half their thickness.




I had to shave one side of the bottom nut to clear the pressure line casting

[Resbum]

I also had to press the housing out for the middle line so that I could still use the magnet and screen that was over the oiginal hydroboost return.


The face of the nut is flush with the original housing surface so the magnet and screen sit in their original lacation. Notice a little bit of thread from the AN fitting sticking through. That's to keep the magnet centered.




The final product. The new pressure line will come straight out and up to the hydroboost.


Oh yeah, also keeping in mind "flow", I cut the original fittings off the cooler, pulled the "turbulator's" out, and silver soldered new #6 AN fittings on. I was really surprised at how much easier it was to blow through the cooler with and without the "turbulator's".

[Elliott]

btt

[Resbum]

Hi Elliott,

I just posted this in my build thread, but thought I'd post it here to see if you or anyone else have any suggestions. Is there a skinnier reservoir I could use or do you have any other ideas on how I can get some more clearance between the master cylinder and the intake plenum without having to cut it up. I can't go any further outboard because I'm mounting a battery between the hydroboost and the hood hinge. That's what the blue tape represents.

Here's what I posted:
Today I got the hydroboost installed. I did end up having to shift the steering column/brake pedal/dashboard support outboard about a 1/4 inch, but that will still easily allow everything inside the cab to be mounted in their stock locations. In the engine compartment the hydroboost/master cylinder ended up getting shifted 3 1/2 inches outboard. That leaves about an 1 1/4 clearance to the battery and I'm going to have to do some tweaking of the Intake plenum I made. The rear brake line out of the master cylinder is only 1 inch in front of the battery so changing batteries will be a real b!tch. I'll take it with no complaining. I'm just glad everything fits because I didn't have a back up plan.

[Elliott]

Have a look at an '80 Eldorado MC.

[Resbum]

Thanks Elliott, after considering all the options I decided to go ahead and cut & reweld the intake plenum so that it points more downward and use a Raybestos MC390279 MC. I've also been digging around for some other answers and can't find any.

What exactly is the performance difference between the Astro and 1 ton HB? I'm beginning to think I have an Astro unit, instead of a 1 ton unit, like I thought. I started really getting suspicious when I noticed the non-removable crimped-end HB pushrod.

What is the HB rod travel length?

Originally Posted by Elliott

...If try to go too short without a spacer you increase the brake rod angle unless you are redrilling the firewall bolt pattern and enlarging the center hole... just extra work over making a 1" spacer and using the aluminum block with the correct 6* angle built in. ....

What 6* angle are you talking about?

Here is a picture of my pedal setup. The main thing is this picture is WITHOUT the OEM cast iron spacer that I had installed in the above engine compartment pictures. With that spacer the pedal was barely off the floor. Without it it's a perfect fit. The HB rod end slides over the 5/8th's brake pedal pin with just a little space before the pedal hits the frame cross-bar stop that the brake light switch also mounts in. Is this a correct and safe setup without that OEM spacer? Also, the spacer gave a slight upward tilt of the HB/MC. Is that upward tilt required? The HB rod starts out slightly low at the pedal end. As the brake pedal travels downward the HB rod becomes an almost perfect staight in push.


Thanks. Resbum

[Carnuck]

Do you know of a master cyl to fit the '88 GM Hydroboost with the lines on the motor side? I'm looking at Hydroboosting my Eagle but the lines go directly into the spring tower.

[Elliott]

Originally Posted by Resbum

Thanks Elliott, after considering all the options I decided to go ahead and cut & reweld the intake plenum so that it points more downward and use a Raybestos MC390279 MC. I've also been digging around for some other answers and can't find any.

What exactly is the performance difference between the Astro and 1 ton HB? I'm beginning to think I have an Astro unit, instead of a 1 ton unit, like I thought. I started really getting suspicious when I noticed the non-removable crimped-end HB pushrod.

What is the HB rod travel length?


What 6* angle are you talking about?

Here is a picture of my pedal setup. The main thing is this picture is WITHOUT the OEM cast iron spacer that I had installed in the above engine compartment pictures. With that spacer the pedal was barely off the floor. Without it it's a perfect fit. The HB rod end slides over the 5/8th's brake pedal pin with just a little space before the pedal hits the frame cross-bar stop that the brake light switch also mounts in. Is this a correct and safe setup without that OEM spacer? Also, the spacer gave a slight upward tilt of the HB/MC. Is that upward tilt required? The HB rod starts out slightly low at the pedal end. As the brake pedal travels downward the HB rod becomes an almost perfect staight in push.

Thanks. Resbum

The block put 6* on the booster, you are fine like that as long as the rod doesn't hit on the back of the booster stub when you articulate the pedal and it doesn't look like it will the way you mounted it.

The amount the brake rod travels is the same on all the HB units, it's travel is limited by the stroke of the MC There won't be much variance between an Astro and 1 ton HB as far as line pressure... maybe 15% and the size bore of the MC makes some variance in itself.

Looking at your setup it didn't seem like anything but modifying your plenum would give you the clearance you were looking for so I think you've done the best you can.

[Elliott]

Originally Posted by Carnuck

Do you know of a master cyl to fit the '88 GM Hydroboost with the lines on the motor side? I'm looking at Hydroboosting my Eagle but the lines go directly into the spring tower.

Hmmm, going to an Eagle... y'all are stretching me here..... you can go to a remote res MC (Dodge ports are on the other side but the bolt spacing is 3.2" not 3.4).......

Looked at other possible options I know of but they were also all on 3.2" bolt centers so at this point I don't have a recommendation for you.

[Resbum]

Great. Thanks for the answer. Custom brakes are something I don't just take for granted. I figured I was OK, but definitely wanted your input.

Resbum

[Resbum]

Another question. I've found a source for the GM PS fluid, but can't find an answer for the fluid capacity of a hydroboost/PS system.

How much PS fluid does the system hold?

Thanks. Resbum

[Carnuck]

It gets filled from the PS system and adds approx 1 quart with the lines and accumulator.

[Elliott]

Originally Posted by Carnuck

Do you know of a master cyl to fit the '88 GM Hydroboost with the lines on the motor side? I'm looking at Hydroboosting my Eagle but the lines go directly into the spring tower.

Ok, your calipers are going to be fairly small so this might just work. Have a look at the '97 Camaro MC. It has the ports on the passenger side of the MC. It fits a GM hydroboost fine (I sell a '97 Camaro - Firebird Hydroboost) but the reservoir is tilted and small for many 4x4 rigs. You can look up and compare your caliper piston sizes at www.rockauto.com This might just work for you.

[Resbum]

.
MASTER CYLINDER FYI

I hit another snag yesterday when I got back to the shop with the new master cylinder. On the left is Raybestos MC390279 on the right MC390257.



The reservoir for the 1996 Chevy P30 van is wider than the reservoir for the 1996 Chevy K2500. I was right back to the original problem of it hitting the air intake before I bent it more downward.

The aluminum housings appeared to be identical and the internal bores are listed as the same. I didn't want to make assumptions with something as important as brakes, so I called Raybestos tech support and ended up in a conference call with two extremely helpful guys there. They pulled out all their build documents and started comparing the two master cylinders.

The only known difference there is, is a slight difference in stroke (.080" difference). The only possible unknown is the spring tension of the internal springs.

THE VERDICT- After thoroughly explaining the mods to my truck and its future intended uses, one master cylinder is as good as the other. If I wanted to be absolutely paranoid about it I can pop the reservoir off a MC390257 and put it on a MC390279. That's what I'm going to do only because I already have both. However, I now have a good spare MC for the future that I know is up to the task.

Mine is an extreme case only because I know there are going to be some really heavy loads in the 1-ton truck I'm building. I think for the vast majority of FSJ'ers doing a hydroboost conversion get either one.

Resbum

[Elliott]

Yeah, they are swappable reservoirs like the Astro. I just never liked the skinny front section on the one and always swap them out because I'm not sure they hold enough juice for rear disc brakes. Maybe they do but they were designed fro rear drums and like the Astro res, that one section seems way small.... maybe just for brake bleeding though.

[Resbum]

Yep, I know what you mean. It was a concern of mine, too. Two things kinda made me decide it's OK to do it.

1- After walking several wrecking yards I noticed that the reservoir on the MC390257 is large compared to almost all the others I saw. And the one on the MC390279 is huge compared to the others.

2- Both MC's have a notch that goes about half way down the internal wall that separates the front and back half's of the reservoir. Until the MC is about half empty the same fluid is servicing both half's. If I ever let it get below that point I wasn't servicing it properly. And that's my bad.

Then there's the fact the large reservoir doesn't fit my available space, so I don't even have a choice.