Alec

I don't get much time to spend around here anymore, so I'm going to have to post a little prematurely.

I'm amassing parts to convert the truck over to hydroboost. This is made more difficult by the fact that it is very hard for me to get to a junkyard, so I can't just go pull a unit & hoses, etc. from a likely looking donor, and have been buying from the local big box auto store and the evil internet. So far I have purchased:

A new hydroboost unit on eBay (GM # 15854059) for a 2003-2007 Silverado pickup (used on pretty much everything 1/2 to 1 ton those years). It was cheaper than a reman, and comes with a nice flat mounting plate that I can re-drill to match the bolt pattern on the firewall, plus the pushrod, spring, and retainer for the MC side of the unit which most remans exclude. The pedal pushrod length and pivot diameter may require some doing, however. The pushrod seems to be a little short, and the pivot diameter a little large.

A reman master cylinder for a '99 3/4 ton chevy diesel pickup. This has a 1 1/4" bore verses the original Dodge 1 1/8" bore, but I expect that the hydroboost will more than make up for the reduction in mechanical advantage. The outlets match the Dodge lines with 9/16 threads for the rear brakes at the front of the cylnder, and 1/2 threads for the front brakes. The unit from a 1 ton has the same bore, is more expensive, but has a larger reservoir (not included with the reman at my source). I would avoid a post '00 master cylinder, as they jumped up to a 1 15/16" bore when they went to four wheel disc brakes.

One -6AN to M16 x 1.5" Adapter Part Number # 023-FCM2608 and two -6 Male to 18mm-1.5 O-Ring Seal Part Number # 799-648080 adapters from JEGS. If you are using a stock auto-type power steering pump you will need two of the M16 adapters instead of one. These adapters allow you to have AN or, cheaper and plenty good enough, JIC 37 degree hydraulic hose assemblies made up to connect the pump to the booster and the booster to the steering gear. The return lines are just hoses over barbed connections, so no special adapters needed there.

At this point I would be ready to start in on the mounting of the hydroboost unit to the firewall, and seeing if I need to frankenstein the old & new pedal pushrods together (I'm thinking I'll thread the two cut-off pushrod pieces from the old & new boosters and use a union nut if I have to go there), but . . .

I am also removing the vacuum pump and stock power steering pump and replacing them with an air compressor and power steering pump from a bluebird bus.

I bought the air compressor & pump from Kadingers -- found the listing on the internet and called them. The compressor is a water cooled Holset unit with NO unloader mechanism. (I would recommend finding a unit with an unloader, if possible.) This means that I have to plumb for an unloader circuit back to the compressor intake and use an unloader control valve instead of just a pilot unloader (or governor) that would open the valves in the compressor. (I bought an unloader valve from drillspot.com, which was an easy and somewhat less expensive way to buy it from Graingers & have it delivered.)

The compressor mounts to the timing cover using the SAE B two bolt flange. It came with its input gear. The back side of the compressor has an SAE A two bolt flange, and a female 1/2 inch 11 spline drive. It also has an inlet for the line from the engine oil gallery (as used by the 91.5 & up vacuum pumps).

I am planning to pull coolant from the port at the rear of the head on the driver's side, and return it to the port just next to the heater outlet on the front of the head.

Unfortunately, the plug in the "intake manifold" that I believe is used as a source for filtered and charged air to go to the compressor intake is blocked by the injector lines, so I will have to find another air source.

The pump is a TRW hydraulic pump with built in pressure relief. It uses o-ring style fittings (the real SAE ones, with o-rings under lock-nuts) and came with a barb adapter for the suction and JIC adapter for the pressure line. I still haven't pulled all of the numbers from it to look up the complete specs. Based on the eyeball, my only concern is that the flow rate may be too high!

The compressor just squeezes in between the timing cover and the motor mount bracket. I will have to fabricate a little bracket to jump from the motor mount to a boss on the compressor housing to hold up the back of the unit. The pump just squeaks over the mount bracket. The good news is, that physically it all fits in there without modifying any other assemblies.

Ordered a 1 gallon reservoir from surpluscenter.com for the power steering hydraulics.

Bought an air tank from a 5 ton Army truck from "surplusboys" on eBay -- really my old friends from WV, Clark Truck Parts.

So, a lot of plumbing parts and work left to do.


BUT, if I can get through it all, I should have bullet proof hydroboost brakes, and on-board air to run my exhaust brake, air bags, and the occasional impact wrench, etc.



If anybody has been through this already, and has any pointers, I'd be glad to hear'em.

Thanks,

Alec

dieselman89

On a similar setup on an international, I employed the use of a hand operated cable throttle to help bring the engine off idle when extended air use is needed...... works better than a brick

wannadiesel

I would suggest rethinking your coolant plumbing. I don't think you are going to get much flow with that port selection.

A lot of compressor installations (including the Cat 3126 in my work truck) run a length of hose to the clean side of the air filter for the compressor inlet.

I didn't see any electric vacuum pump in your plans. Does your truck have A/C?

Alec

I have been worrying about the cooling port selection a little bit. Does anyone have some schematics for auxiliary cooling routing?

I'll pull the intake through the air filter one way or another.

I just didn't mention the electric vacuum pump for the heater controls . . .


Found the specs on the TRW pump: PS series 251615L1 . . . 4.23 gpm and 2,175 psi. I'm pretty sure that the hydroboost & steering gear are only good for 1500 psi, so, need to remedy that.

wannadiesel

It's OK to take the coolant from where you are planning to, but the return needs to be teed into the heater return (the one that goes down by the water pump).

The whole head is pretty much at the same pressure, so you would have had very little flow if any.

freds89

im looking forward to seeing more of this project. let us know on the updates and all.

jensenkennels

Do you have any updates Alec? I'm installing a like setup on my project ( http://www.pirate4x4.com/forum/showthread.php?t=448507 page 9, post #404) Vanco hydroboost/Midland air comp./Sun Performance PS pump with hydro assist.
I'm interested where you tie in for your coolant in/out and the "bracket to jump from the motor mount to a boss on the compressor housing to hold up the back of the unit".

kiszka6911

I used did mine using older chevy parts from the 90's. I think my orginal post and parts used was added to the sticky. See my pictures for the install pictures.