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My four wheel disc brake swap.

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My four wheel disc brake swap. Empty My four wheel disc brake swap.

Post by fasrnur on Fri May 01, 2020 7:59 pm

So first I would like to thank Patrick Tubick for inspiring me a couple of years ago to do this big brake rear disc brake swap. Thank you sir.

This is a very long post about how I did this swap. It took me about a week and a half from start to finish for the install.

It has been a long journey to get to the finish line on this project for sure. The amount of hours I spent on line researching all the correct parts to order and where to get the parts for the best price was a true challenge. Below is a list of parts I used and the websites I found to have the best price at the time I ordered the parts.

Let me say the two major items that are the hardest parts to find for the way chose were the front spindles for the 12" rotors, and the rear caliper mounting brackets.

I will not be posting where I got them because honestly, with all the searching I did I can't remember for sure. Sorry!

The first thing I'll talk about are the front spindles. The 80-89 B-body GM's use the 12" rotor and you can do the swap without changing the ball joints. The 90-96 I've heard you might have to swap out ball joints and because of that I went with the earlier spindles. The best place to find these are if you go to Car-Part.com and follow all the drop down menus you should be able to find something in your area.

The second thing that is hard to find is the rear caliper mounting brackets that I used. I've heard of other cars/trucks that you can use to get to the same end, but I chose the 4th gen Camaro/Firebird setup. To find these I used my wisdom and charm to get them. I also went to Car-Part.com and did the same thing as I did with the front spindles. I looked up a rear caliper and found a yard that showed the had both sides on hand. I then called them and asked if they were still on the car. If they said yes, I would them order them telling the yard, or asking first, if they would sell me the mounting brackets that mount to the rear end also. For me, it worked.

So once I had the hardest parts to find I moved on to figuring out the front rotors. I chose to use the 88-92 Camaro 1LE rotors to get the proper size and size of wheel bearings to fit the spindle. The major companies will have the part numbers of Set3 for the outer bearing and Set6 for the inner. The inner seal is the same as our cars, so no problem there. NOW, since the 88-92 Camaros have metric studs in them, that presented a problem. No problem for this old fart. I got my thinking cap on an started surfing the web. Low and behold I found that they sold the 88-92 Camaro 1LE rotors that already had the S.A.E. studs in them . Bingo! ordered them speedwaymotors.com/1988-92-Camaro-1LE-12-Inch-Brake-Rotor,5...

One thing after trying to install my calipers with stock new pads I found that they won't work due to the fact the 1LE rotor is thicker than our stock rotors. CRAP! So back to the old thinking cap and inter web. Knowing that the 94-96 B body cars use the same design of caliper as ours, I looked up a set for a 94-94 Impala SS and found that they are thinner. WOOHOO! Ordered a set , installed them and they fit like a glove.

Now on to the rear rotors and pads. Since I already had my calipers on hand, I simply went to Napa online and ordered up a pair of rotors and pads in a kit. Easy peasy.

Now knowing that having 4 wheel disc the proportioning valve would be different, I once again went to the web and dug around. I found a disc/disc proportioning valve, mounting bracket, and lines to the master cylinder and ordered it them. swperformanceparts.com/PV2K-2/

Seeing I was going to all the trouble of searching for things and planned on replacing EVERYTHING, I might as well go with all new stainless steel brake hoses. The front and rear hoses are from our cars and the rear ones fit the 4th gen Camaro/Firebird.

swperformanceparts.com/PV2K-2/ for the front hoses, and

foundersperformance.com/…/camaro-firebird-axle-caliper-st…/… for the rear.

Of course with the rear hoses being from the later model cars, they will have a bubble flare fitting. So you'll need to put a bubble flare on that end and an inverted flare on the other end that goes to the tee on the middle of the rear hose. Since I'm talking about flares and again I wanted to replace every it of my brake system, I chose to use copper nickel line for the hard lines. amazon.com/Brake-Line-Universal-Size-Copper-Ni…/…/B07BMZ5FV2

You want more pressure than volume for this. I researched this to length as well. I went with 3/16" line for the entire system and it seems to be a great help. Pl
Plenty of pressure throughout the lines.

Now for the last thing, and again I researched the heck out of the subject. I found that a 1" bore master cylinder would be my best bet. Well, I ordered up one. This is the one thing that is still driving me nuts. I bench bled a brand new master cylinder so many times I can't count. I just can't get any fluid out of the front port when it's on the car. I do know about the push rod from the booster to the master cylinder has to be the correct length, and I will go back and check that at a later date. But for now I have the original master cylinder on the car and it works just fine.

SO that's what I did, and the parts I chose. If you choose to use these parts, it's at your risk and I take no responsibility for anything that might happen to you. haha

Have fun and take care folks. Let's all get out there and enjoy what we can in our cars.

Jeff...

My four wheel disc brake swap. 20200411
My four wheel disc brake swap. 20200412
My four wheel disc brake swap. 20200410


Last edited by fasrnur on Fri May 08, 2020 11:47 am; edited 3 times in total
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Post by fasrnur on Fri May 01, 2020 8:00 pm

My four wheel disc brake swap. 20200415
My four wheel disc brake swap. 20200414
My four wheel disc brake swap. 20200413
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Post by fasrnur on Fri May 01, 2020 8:02 pm

My four wheel disc brake swap. 20200416My four wheel disc brake swap. 20200418
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Post by REVINKEVIN on Fri May 01, 2020 9:31 pm

Way to go. That’s looking real good.
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Post by fasrnur on Fri May 01, 2020 11:11 pm

Thanks Kevin. It can stop damn good too. The wheel cribs I made also double as some nice jack stands too.
My four wheel disc brake swap. 20200419
My four wheel disc brake swap. 20200421
My four wheel disc brake swap. 20200420
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Post by 76 Malibu on Sun May 03, 2020 11:44 am

Great post and swap. I like that it uses mostly off the shelf parts.

One question. Do the B-Body spindles have the same steering arm geometry as the A-body spindles? I know when this swap was done with the 68-72 Chevelles the taller spindles caused poorer steering geometry and more bump steer in the old Chevelles.
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Post by fasrnur on Sun May 03, 2020 10:02 pm

Thanks 76Malibu.
From everything I've read on this swap it doesn't have any worse bump steer than the factory. When I had the stock spindle and the the one for the 12" rotors side by side, they looked like they were the same height to me.
I know I have to get it aligned after i put all new tie rods, idler arm, and center link on it this week. The drive I took it on was only about a 5-6 mile ride and it seemed to be fine. I guess I'll find out after it goes to the alignment rack.
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Post by Iggy on Mon May 04, 2020 7:45 am

1977 and up B bodies have the same front geometry as the G3 cars
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Post by fasrnur on Mon May 04, 2020 9:56 am

Thanks for the info Iggy.
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Post by g3chevy on Mon May 04, 2020 11:43 am

Great info Jeff! Thanks for sharing all the gory details. Much appreciated.
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Post by 76 Malibu on Tue May 05, 2020 6:52 am

While the suspension on the B-bodies and G3s share similar geometry, I was more concerned about the steering geometry.  If there are differences between the two spindles in terms of steering arm length and location this will effect the steering geometry. It can possibly create bump steer.  From reading the original GM heritage kits for the 1977 Chevrolet Impala and Malibu, I see that the ratio between the steering box and the linkage is different between each platform.  The 1977 B-Body has a steering box to linkage ratio of 1.175:1 and the A-Body is 1.23:1.  So that means, the B-Body steering linkage is quicker than the A-Body, so the overall ratio is closer to the box ratio.

And since we brought up the suspension discussion, I know it's been said that the G3s and the B-bodies are the same suspension. There is no doubt they are related, but i wonder if there are some subtle differences were are no aware of.  I know the control arms have different part numbers, but i have been told that this was only because of the Metric fasteners on the B-body.  Looking at the GM Hertiage Kit info, GM also lists a different spring to wheel ratio for each car. So maybe there are other differences we are not aware of.

1977 B-body:

My four wheel disc brake swap. 1977_c10



1977 Malibu

My four wheel disc brake swap. 1977_m10
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Post by thatfnthing on Tue May 05, 2020 8:19 am

76 Malibu wrote:While the suspension on the B-bodies and G3s share similar geometry, I was more concerned about the steering geometry.  If there are differences between the two spindles in terms of steering arm length and location this will effect the steering geometry. It can possibly create bump steer.  From reading the original GM heritage kits for the 1977 Chevrolet Impala and Malibu, I see that the ratio between the steering box and the linkage is different between each platform.  The 1977 B-Body has a steering box to linkage ratio of 1.175:1 and the A-Body is 1.23:1.  So that means, the B-Body steering linkage is quicker than the A-Body, so the overall ratio is closer to the box ratio.

And since we brought up the suspension discussion, I know it's been said that the G3s and the B-bodies are the same suspension. There is no doubt they are related, but i wonder if there are some subtle differences were are no aware of.  I know the control arms have different part numbers, but i have been told that this was only because of the Metric fasteners on the B-body.  Looking at the GM Hertiage Kit info, GM also lists a different spring to wheel ratio for each car.  So maybe there are other differences we are not aware of.

There will never be a comprehensive answer from the factory as to all the differences and what will/may be affected, so in the end the only way is to try it and find out.  Having swapped the 93 B-body spindle to the G3 arms for my ABS conversion, I can report that the only differences I have encountered worth noting (beyond english vs metric) are that the wheel sits inboard 1/4" from where it used to be, and the steering arm on the knuckle is a little off -- but an alignment was going to be necessary after that swap anyway, so no big deal. I can also report that the car tracks properly and there is zero bump steer.

I've found that it also helps to think of it from the factory perspective.  GM is going to re-use a part wherever possible to save money.  They're not going to totally redesign a part just for the sake of redesigning it.  So if they had a working part that only needed a little tweaking to be used in the new application, that was going to save a lot of money across a million units.  So it wouldn't surprise me at all if those are the ONLY changes to it.

You can homework the hell out of any project (and should), but at some point you just have to go for it. Smile
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Post by 76 Malibu on Tue May 05, 2020 9:03 am

thatfnthing wrote:

There will never be a comprehensive answer from the factory as to all the differences and what will/may be affected, so in the end the only way is to try it and find out.  Having swapped the 93 B-body spindle to the G3 arms for my ABS conversion, I can report that the only differences I have encountered worth noting (beyond english vs metric) are that the wheel sits inboard 1/4" from where it used to be, and the steering arm on the knuckle is a little off -- but an alignment was going to be necessary after that swap anyway, so no big deal.  I can also report that the car tracks properly and there is zero bump steer.

I've found that it also helps to think of it from the factory perspective.  GM is going to re-use a part wherever possible to save money.  They're not going to totally redesign a part just for the sake of redesigning it.  So if they had a working part that only needed a little tweaking to be used in the new application, that was going to save a lot of money across a million units.  So it wouldn't surprise me at all if those are the ONLY changes to it.

You can homework the hell out of any project (and should), but at some point you just have to go for it. Smile

Thank you, this answer is very helpful.  Based on your description of the differences on the parts, they don't sound identical, as I suspected. I agree that GM obviously used the G3 suspension as the starting point (which was originally used in the 1970 F-body), but it does some some minor tweaking was done along the way. However, they appear to be close enough that they work well together in the real world despite the minor differences, unlike when using B-body spindles on the older A-bodies.

FWIW, I wasn't questioning whether this swap would work, I was just more curious how close the suspension and steering geometry actually was. I would have no hesitation in doing this swap.
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Post by Iggy on Tue May 05, 2020 1:44 pm

Just a little history on the front neutral geometry used on the G3's, it was originally from the C2 Corvette, did not change for the C3 Corvette. Mention that to a Corvette nut and watch the fireworks! The second generation F Bodies robbed that from the Vettes, as did the G3's and 1977 and later B Bodies. It was also used on the 1/2 ton vans.

GM really got their mileage out of that design!
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Post by fasrnur on Wed May 06, 2020 7:27 pm


I want to thank you folks for your comments. I, as well as others, have learned some new things about the B-body spindles and their slight differences.
I put new tie rods, idler arm, and center link on the car today. I then took it for another ride. I have to say I'm very proud of myself in how well the car stops now. I wouldn't be afraid to put it up against newer cars in a stopping contest. Very Happy
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Post by impalamonte on Thu May 07, 2020 8:37 am

Very nice write up and great work !!

Next on your list.....Hydro-Boost

Page 4 & 5 , here :

https://www.g3gm.com/t8709-update-1973-monte-carlo-body-off-frame-resto
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Post by fasrnur on Fri May 08, 2020 11:36 am

Thanks impalamonte. It was worth every second I spent on the research and installation. I had considered a hydra boost at one time, but now I don't feel as though I need one. My big old Turd can stop very nicely and quickly. I'm going to have to go out and do some stops to see what kind of distances it takes to stop from 60.
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