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55trucker

Booster Upgrade for 88-93 cars

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For as long as my wife & I have owned the GP the brakes have always been a ? (question mark), I have never liked the way they responded when applied, the fronts have always done more than what they were designed to do & the rears have always just *gone along for the ride*.

In the past I have had the booster recalibrated to try & make it more effective, I've had the master apart to get a good look inside it to see just what the engineers at Delco Moraine were thinking of when they came up with this design.

For those of you who drive a pre 94 car with no ABS you probably are suffering with the same issues that my car has been crippled with.

I am in the process of a 4 corner upgrade for the brakes, all corners will get near 12" rotors, the fronts will keep the dual piston caliper as it is a decent piece, the rears are getting a set of late model Ford Explorer/Flex/Taurus large 1.9" dia piston calipers that will be mounted to a custom support that I am designing to fit the rear knuckles. The front rotors are donated by Ford (late model Fusion front rotors), the rear rotors are courtesy of a 2005 Pontiac Montana 2wd drive vehicle (shallow hat). These custom items have been sitting on my workbench for some time now waiting for me to get started on this job. The nice thing about the Ford rear calipers is that the  GM rear parking brake cables are a near match for the mechanical parking brake lever on the calipers.

But for now I wanted to get at the damned booster, I have upgraded the old small booster for the booster that GM installed on all of the post 93 cars. It is a significantly larger booster in both diameter and depth. The old booster is 9" in dia whereas the newer version is 12".

1594755687_Boostercomparison1.thumb.JPG.8ae2c276e8644dec7c33ed38eb7afb81.JPG

1583343151_Boostercomparison3.thumb.JPG.8aa34f7587e51a0f8ed664697b3eeda3.JPG

     

To get this into the engine bay was no small feat, it's not just a case of out with the old & in with the new, aside the air intake assembly coming out if one's car is fitted with the LQ1 engine the intake plenum has to come off, the exhaust crossover comes out, the drivers side shock tower has to be cleared of all the items attached to it, the fuel lines disconnected & swung out of the way & the master cylinder is removed on it's own.

 

Before the larger booster can fit in the suction side a/c piping has to be changed, the old design will accommodate the smaller booster but not the larger piece. One has to order the 94+ suction pipe as it's shape is reconfigured to allow clearance along the bottom for the large booster. I did this, ordered from Rockauto, but there's more to it than that, seeing as I kept the a/c receiver dryer that is in the car I had to cut off the end of the pipe & swap the fittings & a trip to a friend's welding shop allowed me to tig the end of the pipe back on because the receiver dryer was altered for the 94 year & the fitting thread pitch changed.

 

 

 

393267262_Oldboosterremoved1.thumb.JPG.edcfa7a62e4171def5a7e553d1138ba3.JPG

582186304_Fittingremovedfromcutpipe1.thumb.jpg.804d8b423e7e1f8473615ac8276c412c.jpg

1626325503_Fittingswapendofpipe.thumb.jpg.88773a09b41a7eb3de5cb18bc490c983.jpg

1115623755_Fittingsswappedpipetigged.thumb.JPG.758a033f15e946334b2a6ef84c889100.JPG

942044039_Threadpitchendofpipe1.thumb.jpg.2fb65811c9a5c1d10838c734560e6024.jpg

722305479_Thrreadpitchendofpipe2.thumb.jpg.3f71a5f2696499a0b77dec27f3abeb25.jpg

Once that was out of the way the pipe went back into the car, & I then could go about drawing a vacuum for the a/c system to test for leaks.

Next on the menu was the reconfiguring of the heater core inlet side piping. I had to cut the pipe in several places to *extend* it to reshape the pipe to get around the new booster. After getting what I needed I brazed the assembly back together again. This involved the booster going o n/coming off multiple times to get the angles I was looking for for clearance sake.

 

1939836032_Heatercorepiping1.thumb.jpg.a2be04b24b89fa67c01ed7d33a748a40.jpg

93280729_Heatercorepiping2.thumb.jpg.3d168431609b10c30e3f312669e4fa99.jpg

 

69066684_Enginebaynobooster.thumb.JPG.2c9302e1c379783086e926dc50c38aff.JPG

 

The pipe at the engine end actually is now approx 3/4" higher, I had to reconfig the small bracket & braze it back on at the corner & cut the upper section off to clear the cowl seal.

With that all of the *heavy* construction is out of the way, painted what was needed to be painted & started reassembling things, the a/c line is in.... the booster can go in also, 

 

166122739_Boosterinstalled.thumb.JPG.b0a5bd0c52a1bacb4bae26a8e0d10856.JPG

 

1821385700_P9070099(Large).thumb.JPG.1a7cf66f65596926d65c901a8b4f84e8.JPG

1942064463_P9070103(Large).thumb.JPG.4914f1efc87465d053900f6c708ecbf1.JPG

With the booster in place the pedal is reconnected to the pushrod under the dash.

From here it was just a matter of putting everything back into where it lives, fill the coolant again, run the engine to bleed it, pull the wheels to bleed the brakes & test the new booster for what should be a pleasant surprise.

This was not a cut&dry install, the booster cam-lock gave me fits, I had to in small amounts bend the tabs on the back of the booster multiple times to get them to align with the firewall cam-lock (I spent about 5 hrs adjusting-test fit-adjust - test fit etc before it freely went into place).

But in the end it was all worth the effort, the difference in the pedal force needed to be applied is like night & day, the old booster would force you to push & push to get the calipers to respond, and then one could not get the calipers to *instant bite*. The new booster is a whole different story, the pedal effort is so light you could stop the car using your hand on the pedal. The car now comes to a near instant stop, the calipers react sooner & harder on the rotors, they never did this before.

To say I'm pleased is an understatement.......,

 

 

 

 

Edited by 55trucker

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3 hours ago, Schurkey said:

My upgrade story is way less involved.

Selecting the newer 12" booster requires the changes I had to make, if I had the later heater hose inlet pipe on hand I wouldn't have had to refab the current piece, the 12" booster also dictated the need for the later a/c pipe as well. I wasn't aware that GM altered the threaded fitting on the receiver/dryer end.

The car stops decently now..........for the last 28 it did not.

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Crazy...  I have great admiration for the fact that you figured it all out and got it back together...  Such dedication!

Any reason to believe that it might be different/easier for the 3.1?  Can't touch my AC (its R-12....).  

 edit:  checked my 1992, its identical in terms of the AC lines running under the (smaller) booster and would need very similar AC mods.

 

(I presume you've done the strut knuckle/tower replacements to the 94+ versions, right, to fit the larger rotors -- I personally found such very useful on my 1992!)

Edited by pitzel

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Interesting, for ages I've just assumed it was a drop in replacement. 

I, personally found Schurkey's article informative and just put in a reman original booster in my car as I had no other choice since I have a manual transmission and need the smaller booster to clear the clutch master.

I seem to remember some time back some guys putting 2g boosters on first gens, they are deeper but not much wider.

Regardless, good work and good information. 

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On 9/8/2019 at 4:31 AM, pitzel said:

Crazy...  I have great admiration for the fact that you figured it all out and got it back together...  Such dedication!

Any reason to believe that it might be different/easier for the 3.1?  Can't touch my AC (its R-12....).  

 edit:  checked my 1992, its identical in terms of the AC lines running under the (smaller) booster and would need very similar AC mods.

 

(I presume you've done the strut knuckle/tower replacements to the 94+ versions, right, to fit the larger rotors -- I personally found such very useful on my 1992!)

No, I have other plans for the front knuckle assembly, I am keeping my older knuckles ,it will involve cutting/removing the welds that hold the caliper support to the the knuckle, then I have to reconfigure the caliper support by shearing off the end, fabbing a section from some high strength alloy to be welded into the support at the cut points, then the support will be re-welded back onto the knuckle so as to place the caliper in the proper location for the 12" rotor. (essentially doing what GM did when they installed the 11 1/4" rotors in place of the 10 1/2"..of course their support was a ready made stamped piece that fits the application)

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2 hours ago, White93z34 said:

Interesting, for ages I've just assumed it was a drop in replacement. 

I, personally found Schurkey's article informative and just put in a reman original booster in my car as I had no other choice since I have a manual transmission and need the smaller booster to clear the clutch master.

I seem to remember some time back some guys putting 2g boosters on first gens, they are deeper but not much wider.

Regardless, good work and good information. 

A the time I approached this I was skeptical about choosing one of the pre '94 boosters, I did not want to purchase another 9" item on the thinking that what's in my '91 may very well be in a '93. 23 years ago I had pulled the booster & sent it into the rebuilder (that we the truck shop I was employed at made use of) to open it up & look inside to see what could be altered to make the booster more user friendly,  the return spring was lightened, the reaction body was also replaced but the difference was only marginal. Seems those first  W platform boosters internals were a direct steal from the Fiero boosters & THOSE boosters did not function very well as well. Brake upgrades are common to Fieros, one upgrade includes replacing the original booster with an S10 booster. 

Edited by 55trucker

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I will qualify it with this: I did the booster replace on my Z34 and old Euro 3.4 The z34 worked out way better. even with a reman booster on the old Euro 3.4 the brakes could be called hopeless at best. Perhaps I got a bad one. now on my z34 they were and still are much improved. 

I'm interested to see what you do with caliper/brake upgrades. I currently have the 94+ rears and 96+ fronts which is an improvement over original but I'm always open to better.

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5 hours ago, White93z34 said:

I will qualify it with this: I did the booster replace on my Z34 and old Euro 3.4 The z34 worked out way better. even with a reman booster on the old Euro 3.4 the brakes could be called hopeless at best. Perhaps I got a bad one. now on my z34 they were and still are much improved.

What's different between the Z34 and the Euro 3.4 brakes?  Far as I know, they're IDENTICAL.

I bet you got a booster that works properly for the Z34, and one that still has problems on the Euro 3.4.  The two boosters I bought (both from CarQuest, same part numbers) have slightly different amounts of assist.  My '92 Euro 3.4 always stopped a bit easier than the '93 Euro 3.4.  Of course, it could also be a difference in pad material and rotor condition, too.

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Literally nothing, same same. same year same parts same everything. the Euro just always had extremely poor performing brakes no matter what I did.

I never understood it. I changed so much stuff around. At the end of the day I can only assume that I had just got a defective reman for the Euro 3.4... can't remember where I got it at this point, we sold the car years back now.

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I had no idea the early cars had troublesome or bad feeling brakes.  I'm interested and worried when I get the my 91 car running.  Oh boy..

I can say that the STE has terrific brake pedal feel and stopping power when moving it around with my own muscle and off the trailer, LOL!

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On ‎9‎/‎6‎/‎2019 at 9:40 PM, 55trucker said:

For as long as my wife & I have owned the GP the brakes have always been a ? (question mark), I have never liked the way they responded when applied, the fronts have always done more than what they were designed to do & the rears have always just *gone along for the ride*.

In the past I have had the booster recalibrated to try & make it more effective, I've had the master apart to get a good look inside it to see just what the engineers at Delco Moraine were thinking of when they came up with this design.

For those of you who drive a pre 94 car with no ABS you probably are suffering with the same issues that my car has been crippled with.

I am in the process of a 4 corner upgrade for the brakes, all corners will get near 12" rotors, the fronts will keep the dual piston caliper as it is a decent piece, the rears are getting a set of late model Ford Explorer/Flex/Taurus large 1.9" dia piston calipers that will be mounted to a custom support that I am designing to fit the rear knuckles. The front rotors are donated by Ford (late model Fusion front rotors), the rear rotors are courtesy of a 2005 Pontiac Montana 2wd drive vehicle (shallow hat). These custom items have been sitting on my workbench for some time now waiting for me to get started on this job. The nice thing about the Ford rear calipers is that the  GM rear parking brake cables are a near match for the mechanical parking brake lever on the calipers.

But for now I wanted to get at the damned booster, I have upgraded the old small booster for the booster that GM installed on all of the post 93 cars. It is a significantly larger booster in both diameter and depth. The old booster is 9" in dia whereas the newer version is 12".

1594755687_Boostercomparison1.thumb.JPG.8ae2c276e8644dec7c33ed38eb7afb81.JPG

1583343151_Boostercomparison3.thumb.JPG.8aa34f7587e51a0f8ed664697b3eeda3.JPG

     

To get this into the engine bay was no small feat, it's not just a case of out with the old & in with the new, aside the air intake assembly coming out if one's car is fitted with the LQ1 engine the intake plenum has to come off, the exhaust crossover comes out, the drivers side shock tower has to be cleared of all the items attached to it, the fuel lines disconnected & swung out of the way & the master cylinder is removed on it's own.

 

Before the larger booster can fit in the suction side a/c piping has to be changed, the old design will accommodate the smaller booster but not the larger piece. One has to order the 94+ suction pipe as it's shape is reconfigured to allow clearance along the bottom for the large booster. I did this, ordered from Rockauto, but there's more to it than that, seeing as I kept the a/c receiver dryer that is in the car I had to cut off the end of the pipe & swap the fittings & a trip to a friend's welding shop allowed me to tig the end of the pipe back on because the receiver dryer was altered for the 94 year & the fitting thread pitch changed.

 

 

 

393267262_Oldboosterremoved1.thumb.JPG.edcfa7a62e4171def5a7e553d1138ba3.JPG

582186304_Fittingremovedfromcutpipe1.thumb.jpg.804d8b423e7e1f8473615ac8276c412c.jpg

1626325503_Fittingswapendofpipe.thumb.jpg.88773a09b41a7eb3de5cb18bc490c983.jpg

1115623755_Fittingsswappedpipetigged.thumb.JPG.758a033f15e946334b2a6ef84c889100.JPG

942044039_Threadpitchendofpipe1.thumb.jpg.2fb65811c9a5c1d10838c734560e6024.jpg

722305479_Thrreadpitchendofpipe2.thumb.jpg.3f71a5f2696499a0b77dec27f3abeb25.jpg

Once that was out of the way the pipe went back into the car, & I then could go about drawing a vacuum for the a/c system to test for leaks.

Next on the menu was the reconfiguring of the heater core inlet side piping. I had to cut the pipe in several places to *extend* it to reshape the pipe to get around the new booster. After getting what I needed I brazed the assembly back together again. This involved the booster going o n/coming off multiple times to get the angles I was looking for for clearance sake.

 

1939836032_Heatercorepiping1.thumb.jpg.a2be04b24b89fa67c01ed7d33a748a40.jpg

93280729_Heatercorepiping2.thumb.jpg.3d168431609b10c30e3f312669e4fa99.jpg

 

69066684_Enginebaynobooster.thumb.JPG.2c9302e1c379783086e926dc50c38aff.JPG

 

The pipe at the engine end actually is now approx 3/4" higher, I had to reconfig the small bracket & braze it back on at the corner & cut the upper section off to clear the cowl seal.

With that all of the *heavy* construction is out of the way, painted what was needed to be painted & started reassembling things, the a/c line is in.... the booster can go in also, 

 

166122739_Boosterinstalled.thumb.JPG.b0a5bd0c52a1bacb4bae26a8e0d10856.JPG

 

1821385700_P9070099(Large).thumb.JPG.1a7cf66f65596926d65c901a8b4f84e8.JPG

1942064463_P9070103(Large).thumb.JPG.4914f1efc87465d053900f6c708ecbf1.JPG

With the booster in place the pedal is reconnected to the pushrod under the dash.

From here it was just a matter of putting everything back into where it lives, fill the coolant again, run the engine to bleed it, pull the wheels to bleed the brakes & test the new booster for what should be a pleasant surprise.

This was not a cut&dry install, the booster cam-lock gave me fits, I had to in small amounts bend the tabs on the back of the booster multiple times to get them to align with the firewall cam-lock (I spent about 5 hrs adjusting-test fit-adjust - test fit etc before it freely went into place).

But in the end it was all worth the effort, the difference in the pedal force needed to be applied is like night & day, the old booster would force you to push & push to get the calipers to respond, and then one could not get the calipers to *instant bite*. The new booster is a whole different story, the pedal effort is so light you could stop the car using your hand on the pedal. The car now comes to a near instant stop, the calipers react sooner & harder on the rotors, they never did this before.

To say I'm pleased is an understatement.......,

 

 

 

 

Incredible detailed work and a great write up!  Like I've said before, you intellect and dedication to the LQ1 W-Body's is an inspiration to at least me.  Hey, is that the relay cover I sent you?  Nice!

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Well, when the situation gets to the point where ones tolerance of the issue wears  thin ones determination takes over.

The wife won't drive the car (her tag line has become..*sell it*), I don't enjoy being behind the wheel, when on the road a more than average amount of space is has to be maintained from the vehicle in front of you. All the fun goes out the window just because the vehicle won't slow down in an appropriate manner. But you don't blame the entire vehicle because one single part isn't functioning properly. Hopefully now she will have a renewed confidence in the car once again.

 

*yep ...that's the relay cover you sent to me*  :cheers:

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It's great that you have the ingenuity to fix a problem that the engineers didn't.  With the rare cars, you have to come up with fixes on your own sometimes.  Your car is one of the ones that definitely deserve the attention!

I'm worried that I may have to go this same route on my W's.  I want to keep them OEM as much as I can due to their rarity but I obviously don't want to jeopardize my safety or others...and destroy my cars in the process.

I'm glad the relay cover worked out!  Looks nice and at least I can say I helped a little bit on your car.  I'm still going to grab that exhaust shield when I see one.

Edited by jiggity76

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Chris' Z34 is one of the only 1G W cars I've ever driven that feels as if it has an appropriate amount of braking power.

As he alluded to before, the Euro 3.4 was sketchy on the best of days, and downright dangerous on the worst of them. I put many miles on that car, and no point would I have described the braking performance as being "sufficient". While they weren't Euro 3.4 bad, the brakes in my own '92 Z34 were less than stellar. Conversely, the brakes in my first car, a '90 GP LE, could be locked up on command. I know they could, because I used to think it was funny to do it. 

Both my '91 Cutlass and my '90 TGP had decent stopping power, but they were also PM3 cars and that came with it's own flavor of bullshit to contend with, which usually ends in my suggestion to rip it out of the car. 

Between the GXP brakes on the Regal (best upgrade for the 2G cars, hands down) and those on the C5, I'm spoiled. Every time I get into an early 90s GM product, I'm shocked by how terrible the braking performance is. 

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As I said in my original post from years and years ago--I don't think it's the "brakes" that are so bad, but there's a huge number of faulty vacuum boosters.  I used to think that a booster either worked or didn't, but I've come to believe that they can produce "less" assist on a sliding scale--some are extremely bad, some are only mildly bad.

For me, slapping in rebuilt boosters made ALL the difference with the '92, and substantial difference on the '93.  I didn't feel any need for larger-diameter rotors, bigger calipers, etc. on the '92.  I did install Performance Friction "Carbon Metallic" brake pads, and have been buying them for all my other vehicles as well.

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18 minutes ago, Schurkey said:

As I said in my original post from years and years ago--I don't think it's the "brakes" that are so bad, but there's a huge number of faulty vacuum boosters.  I used to think that a booster either worked or didn't, but I've come to believe that they can produce "less" assist on a sliding scale--some are extremely bad, some are only mildly bad.

For me, slapping in rebuilt boosters made ALL the difference with the '92, and substantial difference on the '93.  I didn't feel any need for larger-diameter rotors, bigger calipers, etc. on the '92.  I did install Performance Friction "Carbon Metallic" brake pads, and have been buying them for all my other vehicles as well.

Did you rebuild them yourself or just put in a fresh reconditioned one from a parts store?

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CarQuest reconditioned.  P/N 54-71286; $142.03 plus sales tax. That price includes the $12.86 core charge. (Price was from 2007)  That part number on the Advance web site is actually a few dollars less expensive now, supposedly a Cardone reman with "lifetime" warranty.

Most of these gory details are in the thread I started "way back when", and linked-to in post #2 of this thread

Edited by Schurkey

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5 hours ago, Schurkey said:

CarQuest reconditioned.  P/N 54-71286; $142.03 plus sales tax. That price includes the $12.86 core charge. (Price was from 2007)  That part number on the Advance web site is actually a few dollars less expensive now, supposedly a Cardone reman with "lifetime" warranty.

Most of these gory details are in the thread I started "way back when", and linked-to in post #2 of this thread

Thanks man!  I'll check it out.

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I have a weak booster that's a reman on one of my cars currently I need to swap out. This thing has piss-poor assist right out of the box. The weak booster I was replacing honestly might have had a little more assist to it...

 

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What you're describing is precisely the reason why I avoided the pre 94 boosters. There is/was just too much chance for a hit-or-miss situation. The Cardone reman piece I purchased from Rockauto also would have been a headache to send back seeing as it had to come across the border.

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6 hours ago, 55trucker said:

What you're describing is precisely the reason why I avoided the pre 94 boosters. There is/was just too much chance for a hit-or-miss situation. The Cardone reman piece I purchased from Rockauto also would have been a headache to send back seeing as it had to come across the border.

The 94+ fail in the same way the pre-93's do  in my experience. I've seen several of them with weak assist. In both 94+ and pre-93, most of the cars I've seen with weak brakes had A LOT of miles on them before it was an issue. Typically 175,000-200,000+.

Edited by mfewtrail

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