hydroboost conversion problem
PREMIUM SPONSOR
Joined: Sep 2003
Posts: 2,630
Likes: 217
From: North East Ohio
Ah, now I remember.
I had issues with my drag truck 2 years back when I did the disk conversion, and I took that valve off in hopes to increase pressure to the rear disks.
Didn't work like I had hoped, but you're right, that there is the prop valve.
I had issues with my drag truck 2 years back when I did the disk conversion, and I took that valve off in hopes to increase pressure to the rear disks.
Didn't work like I had hoped, but you're right, that there is the prop valve.
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'96 7.3 F-350 Reg Cab 4x4 - bought new.
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'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
'17 6.7 F-250 KR ccsb 4x4
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
No Prop valve needed. Just leave the system as is.
To Bleed PS system jack the truck up and turn lock to lock. Also push the brake numerous times. Double check your PS lines are in the correct ports as well.
To Bleed PS system jack the truck up and turn lock to lock. Also push the brake numerous times. Double check your PS lines are in the correct ports as well.
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Senior User
Joined: Jan 2008
Posts: 322
Likes: 0
From: Simsbury, CT
ok guys a little update. when the truck is on and the power steering is turned lock to lock it makes a humming noise coming from the power steering gear box. it also makes a humming noise coming from the hydroboost wheel the pedal is fully depressed. Is the line that was previously attached to the vacuum booster supposed to be hooked up to anything? where exactly does each line hook up. Please help guys im getting desperate here.
Thanks,
Chris
Thanks,
Chris
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
ok guys a little update. when the truck is on and the power steering is turned lock to lock it makes a humming noise coming from the power steering gear box. it also makes a humming noise coming from the hydroboost wheel the pedal is fully depressed. Is the line that was previously attached to the vacuum booster supposed to be hooked up to anything? where exactly does each line hook up. Please help guys im getting desperate here.
Thanks,
Chris
Thanks,
Chris
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
How does the brake pedal feel with the truck off?
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Senior User
Joined: Jan 2008
Posts: 322
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From: Simsbury, CT
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Fleet Owner
Joined: Jan 2004
Posts: 26,007
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From: Brentwood,CA
Even if the hydroboost is not working or fails you will have full manual brakes. So with the truck off the pedal should be very firm. What does the pedal do when you pump it with the engine off? It sounds like the rear disc brakes are requiring to much fluid and the master cylinder can not supply the amount you need in one pedal motion. If they firm up when pumped you need to consider adding a 10psi such as this Wilwood Disc Brakes 260-1876 - Wilwood Residual Pressure Valves - Overview - SummitRacing.com . Also these trucks DO NOT have any proportioning valve stock as that feature is all controlled by the RABS system.
Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
Also the noise you are hearing from the steering box sounds like a cavitation issue to me. Is the pump full of fluid? I am pretty sure the pressure hoses can only go in one way but just to confirm the one on the top is the pressure in from the pump and the one lower towards the drivers fender goes to the steering box. Make sure both return lines are the correct 3/8'' size and have no restrictions.
Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
Yeah the stock system is not a great setup. The master cylinder will deliver full pressure to the back brakes then the rabs valve on the frame will limit the pressure based on wheel speed and hold it at that pressure during the entire braking cycle. This makes for fun and exciting panic stops as it won't let you use your full braking potential and it puts way to much stress on the front brakes. It should be a 70/30 split on the brakes but stock it is more like 85/15 and not good IMHO.
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
You have an issue with the actual brake hydraulics no the hydroboost setup. With the truck off you should have a rock solid pedal.
Don't bother with the proportioning valve it is not needed. I speak from experience it is NOT needed. Even in winter ice the brakes function perfect. You either have a push rod issue between the HB and master cylinder or you have air in the system
Don't bother with the proportioning valve it is not needed. I speak from experience it is NOT needed. Even in winter ice the brakes function perfect. You either have a push rod issue between the HB and master cylinder or you have air in the system
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