GM Hydroboost problem - Hot Rod Forum : Hotrodders Bulletin Board -- Hot Rod Forum

Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans Advertise
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Suspension - Brakes - Steering
User Name
lost password?   |   register now

LinkBack Thread Tools
  #1 (permalink)  
Old 05-31-2019, 08:07 PM
Registered User
Join Date: Apr 2019
Location: Tacoma, WA
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
GM Hydroboost problem

I have some hydroboost questions that I hope someone can answer. I have a ‘91 Chevy C1500 with a built-for-street 406 in it. I’ve had the truck for 15 years and the brakes have always sucked no matter what I’ve done to them with stock components. Over the last few weeks, I have converted it to hydroboost and rear disc brakes (all at the same time) but I’m having some issues.

The truck will put you through the windshield when you hit the brakes hard, so my initial problem is finally fixed. The problem I have now is that the pedal has to be almost to the floor to do it. Yes, it’s well-bled, and I should mention that the pedal is firm when it gets to the (almost) floor.

I looked at the geometry of the pedal and pushrod and saw that it was at an angle. I looked into it and found that there was a difference between the hydroboost pedal and the vacuum version, so I got that taken care of, yet still no change.

I should mention that the hydroboost and master cylinder were both reman units, but I don’t think them being defective is my issue since the truck does stop good.

The master cylinder IS a hydroboost master cylinder.

Here is where I think my problem is. There is a pushrod between the hydroboost and master cylinder, that I “think” is too short. I’m using GM components, so I am not sure why it would be too short, which concerns me. There are two different lengths of this pushrod, however there is more than an inch difference between the two, so I don’t think the longer version is going to be correct either as that would stick it out of the end of the hydroboost unit and that would clearly not be right.

One other thing that I noticed is the pushrod retainer at the end of the master cylinder is supposed to sit in a grove. The groove is only a quarter of an inch inside (meaning the master cylinder would only be able to stick inside a quarter inch) and my master cylinder pushes it back further (maybe 3/4”). I’m not sure why this is either, but it’s something I wanted to mention.

So my next step (unless someone on here has some mind-blowing resolution) is to lengthen the pushrod to the master cylinder. It doesn’t feel like something I should have to do, but I think it will correct the problem. I’m just concerned that something isn’t right because I shouldn’t have to do that.

Any thoughts?

Reply With Quote Quick reply to this message
Sponsored Links
  #2 (permalink)  
Old 06-01-2019, 01:12 AM
Registered User
Join Date: Jan 2012
Location: Grand Rapids, MI
Posts: 2,468
Wiki Edits: 0

Thanks: 241
Thanked 554 Times in 439 Posts
Are you running a hydro boost power steering pump?
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 06-01-2019, 04:56 AM
55 Tony's Avatar
Registered User
Join Date: Nov 2018
Location: Cocke County, TN
Posts: 1,306
Wiki Edits: 0

Thanks: 174
Thanked 218 Times in 192 Posts
My 2000 3500 has a lot of pedal travel, but I'll check it to see just how much. Been like that from new so never bothered me.
Young enough to learn ... too old to remember.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 06-02-2019, 06:33 AM
Old(s) Fart
Last wiki edit: Wheelbase database
Join Date: Jan 2007
Location: Virginia
Posts: 5,525
Wiki Edits: 1

Thanks: 141
Thanked 691 Times in 584 Posts
Originally Posted by 55 Tony View Post
My 2000 3500 has a lot of pedal travel, but I'll check it to see just how much. Been like that from new so never bothered me.
X2. Same with my 1999 K3500.
Reply With Quote Quick reply to this message

Recent Suspension - Brakes - Steering posts with photos

Quick Reply

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Please select your insurance company (Optional)


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -6. The time now is 05:48 PM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.