DIY Hydraboost - Backing Plate question
Thread Starter
Drifting
Joined: Aug 2001
Posts: 1,823
Likes: 1
From: Arlington TN
DIY Hydraboost - Backing Plate question
Ok y'all -
before I tear into this project next week, took some prelim (with a tape measure, so not too accurate) measurements of the existing mounting bolts on the firewall. (This is a 74 L48 manual brakes car).
There are 4 mounts/bolts - looks like they are about 3 5/8" across, and maybe 3" vertically. (latter number may be off do to a parallax error as I look at it from the top (and in poor light).
On the hydraboost unit I have, the backing plate has 4 posts, and looks to be pretty close to 3 5/8 square.
Several Questions:
1. Is there an existing model / backing plate that no kidding lines up perfectly to our Vette firewall holes? **I acknowledge my measurements by eyeball/tape are not very exact**
2. Which is easier option? Drill press the plate I have with new holes to line up with the firewall or drill new holes in the firewall? (This assumes that my backing plate and the firewall spots are NOT the same).
Ordering the stuff to make the lines tomorrow.
Standby for futher questions / hissy fits.
(P.S. - doing this in conjunction with a Jeep Box mod. I hope I am not over-hyping what the results of these two mods are going to be. All of you have (generally) had nothing but great things to say about each of these conversions.)
Thanks to all....
before I tear into this project next week, took some prelim (with a tape measure, so not too accurate) measurements of the existing mounting bolts on the firewall. (This is a 74 L48 manual brakes car).
There are 4 mounts/bolts - looks like they are about 3 5/8" across, and maybe 3" vertically. (latter number may be off do to a parallax error as I look at it from the top (and in poor light).
On the hydraboost unit I have, the backing plate has 4 posts, and looks to be pretty close to 3 5/8 square.
Several Questions:
1. Is there an existing model / backing plate that no kidding lines up perfectly to our Vette firewall holes? **I acknowledge my measurements by eyeball/tape are not very exact**
2. Which is easier option? Drill press the plate I have with new holes to line up with the firewall or drill new holes in the firewall? (This assumes that my backing plate and the firewall spots are NOT the same).
Ordering the stuff to make the lines tomorrow.
Standby for futher questions / hissy fits.
(P.S. - doing this in conjunction with a Jeep Box mod. I hope I am not over-hyping what the results of these two mods are going to be. All of you have (generally) had nothing but great things to say about each of these conversions.)
Thanks to all....
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
I forget the exact nature of the mis match between my old vac booster and the HB unit, but I took the HB plate and marked the odd holes with the unit input shaft on center of the old vac booster....and drilled the two other holes....simple, really....
but it sounds like you well on the way to curing two primary chassis complaints about the C3....
but it sounds like you well on the way to curing two primary chassis complaints about the C3....
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
Where did you get your Hydrobooster? Mine came out of a Chebby van, the holes line up perfectly with the Corvette holes. If you have to redrill, do it in the Hydro's mounting plate. On the other side of the firewall, the studs hold up the brake pedal bracket. It's considered a good idea to punch the studs out of the Hydroboost backing plate and insert them through the firewall (and brake bracket) from the inside - it makes disassembly of the brake system MUCH easier in the future.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
This is what I did for mine. There were only 2 studs and it was looking like a PITA. So I welded a couple bolts to a piece of bar stock and stuck it thru the firewall. The hole pattern is off a bit, I think its taller that wide, can't remember. But you need a flat plate to mount to the firewall and the center hole for the booster is dead center in the bolt pattern
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Kieth at Corvette Engineering, one of our vendors, has mounting plates for both manual and power cars that fit the body of any Hydro and are designed to fit the firewall pattern perfectly.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
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Thread Starter
Drifting
Joined: Aug 2001
Posts: 1,823
Likes: 1
From: Arlington TN
<------ Here (on previous page)
Or on the vendors page.
Gratzi!
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Here's a link to his site.
http://corvettengineering.com/
Email him about the plates...I don't recall seeing them on the site.
Pro
Joined: Apr 2005
Posts: 591
Likes: 7
From: Batavia IL
Here's a link to his site.
http://corvettengineering.com/
Email him about the plates...I don't recall seeing them on the site.
http://corvettengineering.com/
Email him about the plates...I don't recall seeing them on the site.
Last edited by Tumarr; Jun 14, 2007 at 11:43 PM.
Former Vendor
Joined: Nov 2005
Posts: 683
Likes: 1
From: Mounds View Minnesota
I just found this thread, musta been sleeping.
I'm working out how much to charge for just the plates and what all needs to be included. Give me a day or two
I'm whats called a tag only vendor, I don't get a listing or a banner....
Thread Starter
Drifting
Joined: Aug 2001
Posts: 1,823
Likes: 1
From: Arlington TN
Update
I drilled two new holes in the backing plate - and it is lined up just beautifully.
As this is a manual brakes car......there are only two mounting bolts.
Anyone think that cinched up good and tight, two bolts are sufficient to hold a booster and a MC?
I can post a pic later tomorrow if needed.
I would think that the backing plate is giving it enough support to hold it enough. Sure drilling holes in the firewall might be better, but I have it snugged up with the factory (reinforced) spots nicely.
Anyone think that wouldn't be safe?
As this is a manual brakes car......there are only two mounting bolts.
Anyone think that cinched up good and tight, two bolts are sufficient to hold a booster and a MC?
I can post a pic later tomorrow if needed.
I would think that the backing plate is giving it enough support to hold it enough. Sure drilling holes in the firewall might be better, but I have it snugged up with the factory (reinforced) spots nicely.
Anyone think that wouldn't be safe?
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
I drilled two new holes in the backing plate - and it is lined up just beautifully.
As this is a manual brakes car......there are only two mounting bolts.
Anyone think that cinched up good and tight, two bolts are sufficient to hold a booster and a MC?
I can post a pic later tomorrow if needed.
I would think that the backing plate is giving it enough support to hold it enough. Sure drilling holes in the firewall might be better, but I have it snugged up with the factory (reinforced) spots nicely.
Anyone think that wouldn't be safe?
As this is a manual brakes car......there are only two mounting bolts.
Anyone think that cinched up good and tight, two bolts are sufficient to hold a booster and a MC?
I can post a pic later tomorrow if needed.
I would think that the backing plate is giving it enough support to hold it enough. Sure drilling holes in the firewall might be better, but I have it snugged up with the factory (reinforced) spots nicely.
Anyone think that wouldn't be safe?
THIS is where you get into a section of design engineering we olde tymers used to call destruction....WILL two bolts be enough to hold that brake cast iron brake assy stuck out about a foot length?? too boot there is no purchase on the bolts...being side/side/lateral?? I say NO...need be vertical, if anything...so hense GM did 4 bolts....
drive enough rough roads and enough vibrations, and so you see what happened to ME on a boat with some minor engine mods....and too boot it was a BOAT, NOT subject to ROAD vibration standards....
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
THIS is where you get into a section of design engineering we olde tymers used to call destruction....WILL two bolts be enough to hold that brake cast iron brake assy stuck out about a foot length?? too boot there is no purchase on the bolts...being side/side/lateral?? I say NO...need be vertical, if anything...so hense GM did 4 bolts....
drive enough rough roads and enough vibrations, and so you see what happened to ME on a boat with some minor engine mods....and too boot it was a BOAT, NOT subject to ROAD vibration standards....
drive enough rough roads and enough vibrations, and so you see what happened to ME on a boat with some minor engine mods....and too boot it was a BOAT, NOT subject to ROAD vibration standards....