One more time, C5 brakes (with parking brake) on GM 10 Bolts

[khkiley]

Hi All,
I've been a long time lurker of this site; it is a treasure trove of information. This is my first post, I hope to make it count!

There are a ton of threads on this and other sites looking for a low cost way to mount C5/C6 disc brakes, WITH PARKING BRAKE, on the back of GM 10/12 bolt rears.

There were a couple attempts to get the S10 caliper plate with parking brake to work, and finally Ed Miller came up with a set a brackets to mount the C5/C6 parking brake and caliper. Unfortunately those are difficult to come by.

I propose that this group may have enough talented people interested in this that as a group it can finally be done.

This thread about Ed Millers brackets closes with what I think is needed, a spacer to adapt the corvette 3 hole backing plate to the 10 bolt axle flange.
https://www.pro-touring.com/forum/showthread.php?p=683220

Modular93Fox created a drawing in AutoCAD of this spacer, and I think it is what we are looking for.
There are some things we need to define take this design to completion.

What rears ? I propose GM 10 bolt for Early A-Bodies and F-Bodies, C-Clip and bolt in Axles to start. I know most are C-Clip, but I have bolt-in in my Pontiac!

What caliper brackets? Readily available brackets from Kore3 - http://www.kore3.com/proddetail.php?prod=10092

Setting these things in stone help us define the dimensions of the spacer, without guesswork.

Now the finished piece will look like modular93fox's design- https://www.pro-touring.com/forum/attachment.php?attachmentid=37746&d=1272503808
We need to determine two things- layout of the holes, and how thick to make it.
For the holes the dimensions of the axle flange can be obtained from Mark Williams Catalog page 56 http://www.markwilliams.com/Catalog/pg56.pdf, Ive attached an image of the small GM flange dimensions- Someone please confirm this is the correct flange!

I don’t have a source for the dimensions of three holes that the corvette hub mounts through, does anyone have this?

The four holes that go through to the axle flange don't need to be threaded, but they will need to be countersunk for the fastener so the plate can mount flat. Will this piece be thick enough ?
I suppose the three holes for the parking brake plate could be threaded, but for simplicity we could use a nut on the back. Any thoughts on this?

Now we need to determine how thick this should be:

From this post https://www.pro-touring.com/forum/archive/index.php/t-68699.html we know the distance from the caliper mount to the hub surface is 2.45"
I don’t have the caliper mounting brackets in hand so I need to make some assumptions about them. First I assumed they mount on the front, wheel side of the flange rather than the back. Second, they are a flat plate of 3/8" steel (the thickness doesn’t matter as I will show in a second), and not machined down in the plane the caliper mounts on.
It is important we define that because if that bracket is flat on the caliper mounting side then we know it needs to be 2.45 inches from the axle flange where the rotor sits, this is forced by the geometry of the C5/C6 brakes. If that number is not 2.45 inches then we need to shim something to make it 2.45 or the rotor will not sit in the center of the caliper.
(Side note- from mark williams catalog http://www.markwilliams.com/braketech.aspx we know the axle standout (distance from axle flange- rotor mounting face to axle housing flange) is 2.812 (again please check my numbers!) to get to 2.45 we need a caliper bracket that is .362, 3/8" is .375 which is .013 too thick. Either my numbers are wrong, the caliper bracket is milled to .362 or the rotor needs to be shimmed .013)

The parking brake plate mounts behind the C5 bearing pack, from here http://www.g-machines.com/forum/showthread.php?p=36621 I get a bearing pack height dimension of 1.705 (Please someone confirm this number is was mentioned as an indirect calculation)
Now since the parking brake plate originally mounted behind the bearing pack, it needs to be shimmed up from 2.45 to the back of the bearing pack which is 1.705. There is one number that I don’t have, which is the thickness of the parking brake plate, which I will call "K". Can someone get that number ?
The final thickness of the adapter needs to be 2.45 - 1.705 - K, or .745 - K. Once we have that number we have the thickness.

I think the bolt in Axles might be different because of the axle retainer and the shim required, but lets start with the C-clip.

Anybody interested in pursuing this further? If enough people work together at this we can produce an AutoCAD drawing to share with everyone, we can get these cut on our own or as a group.

I have a 10 bolt rear with bolt in axles and corvette backing plates to test this on.

I need someone to test my assumptions and to make sure my numbers are correct. I gathered all of this information from the web so my idea is "book smart", it needs to be made practical and "street smart".

Any takers? All input is welcome.

Best Regards,

Kurt

[Apogee]

The thickness of the sheetmetal dust shield that is sandwiched between the hub and the knuckle is .047" with paint. The number of issues with using it as anything other than a dust shield are numerous as it is not intended to serve any structural purpose in the OE parking brake assembly aside from holding the traction control sensor wire and the spring retainer for the parking brake shoe. This is the primary reason that KORE3 does not offer a kit using the dust shield as a "backing plate", but rather manufacture our own structural backing plates to mount the actuators. It's important to note that the C5/C6 parking brake actuator housings are what transmit all of the parking brake torque into the knuckle and are mounted through the knuckle with two M10x1.5 fasteners, not just through the dust shield which happens to be sandwiched between the hub and knuckle. The first thing we did when we designed our rear drum-in-hat parking brake kits was evaluate whether or not the dust shield could be used to our advantage to save cost. The result was that it doesn't have the strength or stiffness required to keep it from yielding under normal parking brake loads, let alone forseeable peak loads. Once it yields (plastically deforms), the odds of it seizing inside the rotor are very high due to misalignment.

Just my $.02 (minus deflation), FWIW.

Tobin
KORE3

[Skip Fix]

Just out of curiosity many of the GM trucks have a 10 bolt and a E brake in the rotor. Not sure how close a fit that would be. Redrill to 5 lug pattern?

Also my wife's Avalanche actually has a 2 piston rear caliper setup with an in rotor E brake.

[khkiley]

Thanks Tobin!

Yes, bolting parking brake actuator to the dust shield is a very bad idea.

Looking at the LS1 and S10 backing plates I made the assumption there would have been a similar backing plate on the C5, having it integrated in the upright complicates things. As you have already found out.

I will disassemble my C5 parts I have to see what I'm in for. Might go back to my original idea of modifying S10 backing plates.

Skip:

In my limited research there are at least two sizes of parking brake shoes, a 7.49" and an 8+ inch. The bigger trucks have the 8+ and the corvette, LS1, S10 and I think B bodies have a 7.49". So there are a couple candidates. The hat on the corvette rotor is shallower than the S10 etc, so the backing plate needs to be pushed out further than what is used for the s10 conversion. It has the advantage that the bolt pattern is the same making that part easier. The caliper mount would be useless (i think), I would grind it off if it got in the way or just leave it if not.

Kurt

[PonchoJohn]

Kurt,
I responded to your questions via PM on Nastyz28. As you've found out, the brake shoe is the same- after I PM'd you, I did some research, and that's what I found. That's good.
I don't have an S10 mount, so I can't do this... yet, but I always figured the caliper ears could be ground off the S10 mount, and a C5 caliper mount placed behind it. This is probably the stumbling block area- is the thickness of the backing plate and caliper mount too great to fit between the flange and the inner rotor?? If so, will the caliper mount need to be modded (cut one of the 4 mounting ears off) so it'll slip around the back of the axle tube? I dunno. If the thickness is not too great, and needs a small spacer/shim, that could easily be fabbed and slipped between the caliper mount and the backing plate. As soon as I can get an S10 backing plate, I'll find out.
Don't give up hope yet- I'm way slow, but I've never given up on my idea.
If you get there first, PLEASE post up!

[khkiley]

John,

If the max thickness of the backing plate (caliper ears removed) and dust shield is less than the max shim out i calculated of .745 we may be lucky.

The plate has a recess which will need to be taken up. I took another look at the HPP s10 article and in the side shot where they show all of the parts stacked on the axle it looks like the backing plate may be on the high side of half inch. I will have to hunt down some backing plates as well.

A nice thing about the s10 caliper brackets is the parking brake cable bracket is already cast in.

It will definately work if the caliper bracket is mounted rearward of the axle flange, but then we will need to shim the caliper mount 3/8" plus the axle flange thickness.

I would rather have it on the wheel side if possible.

Onward!

Kurt

[PonchoJohn]

I agree on the front mount vs rear flange mount- much cleaner/simpler on the front.
I have an extra bracket (the one I used to mount rear C5's on my 71 Trans Am in the stock C5 location) that I can get a thickness off of. I think I'll try the NastyZ boys and see if someone can get me some measurements.

[modular93fox]

I was going to to the bone yeard saturday, but a friend that was going to help with the heavy lifting was buisy. Its been replanned for this Saturday. Going to pick up either a 10 or 12 bolt truck rear end so I can play around with some bracketry out of plexi glass or something. Between the Ed Miller stuff and one found on Trucking magazine.. wicked cool stuff, but its gotta be atleast an arm and maybe both legs... lol

http://www.truckinweb.com/tech/1009tr_1973_chevy_c10_buildup/index.html

and a quick reference to a neat caliper bracket

https://static1.pt-content.com/images/pt/2010/07/1009tr_131973_chevy_c10_buildupbaer_alum-1.jpg

But Having a piece machined out like that would be $$ vs a flat metal bracket with say 2 machined tube/washer like spacer.

clint

[Skip Fix]

Kurt I just figured since the trucks are plentiful and use a 10 bolt, and have more offset(by appearance) to the rotor might be something that could work.

[modular93fox]

Willwoods site shows the truck 10 bolts to be at a 2.42" offset

https://static1.pt-content.com/images/pt/2010/07/flange_diagrammed-1.jpg

Clint

I have a LS1 axle bracket that I need to try and figure out how to measure the offset. I was going through our tool room looking for something that Ive seen at another facility... it looked like a giant tire depth gauge, but measured like a vineer caliper. Atleast that away I could have a 3d model thats pretty accurate.
clint

[1badchevelle]

Well here is something I am working on for my 12 bolt. Its almost complete. I was/am working with a company to offer these but after my computer crashed I lost a lot of the info. So I need to redo so of the drawings. I guess when you have more time than money you can always find a way to get things done. For now this set up will only work on a body rears. I have not tried it on f body.


https://static1.pt-content.com/images/pt/2010/07/Picture003-2.jpg

https://static1.pt-content.com/images/pt/2010/07/Picture012-3.jpg

https://static1.pt-content.com/images/pt/2010/07/Picture077-1.jpg

[modular93fox]

so in your application, you modified the LS1 caliper mount to fit your housing and made your own caliper mounts?
clint

[khkiley]

Chevelle,

That looks good- what is the combination ? It looks like an LS1 bracket, is that a corvette rotor as well ?


Kurt

FYI - There is a great product called dropbox (http://www.dropbox.com/) that backs up your files offline. They have a free version for up to 2G. There are other services as well.

[modular93fox]

I was just thinking... even if that was a choped up ls1 braket... you would still need to find a bone yard willing to remove the axles out of a "good" rear end so you can modify them to fit.
clint

[1badchevelle]

Chevelle,

That looks good- what is the combination ? It looks like an LS1 bracket, is that a corvette rotor as well ?



yes and yes. Machined backing plates and 2 sets of lazer cut brakets and a lot of trial and error.:idea:

[modular93fox]

whats the choice of caliper? normal ls1 calipers dont have threads in the mounting holes correct, alteast the ls1 rear caliper bracket I have has threads for the caliper mount.
clint

[khkiley]

Clint,

I'm going to jump to the conclusion that he's using c5/c6 parts. I think the ls1 parts can be used as is with a spacer.

Kurt

[1badchevelle]

calipers/brakets and disc are c5/c6

[modular93fox]

so are the corvette caliper mounting brackets threaded, if not you probally cut new threads? I think I remember looking through rear knuckles and they were regular holes so I think I just answered my own question. just did a quick search on ebay, looks threaded.

[gort69]

Not to sidetrack the discussion - because I do appreciate the challenge and thought that you guys are putting into this - but why not consider a LS1 rear setup with C5/6 calipers? A few points:

- Same basic park brake setup as C5, and bolts directly to the axle tube flange, but you'll probably need a 3/16"ish spacer between the backing plate and the axle flange to correctly align the rotor in the abutment

- Same rotor diameter and thickness as C5 (12" x 1.02"), the main diff AFAIK is that the LS1 rotor is not directionally vaned. (Is that a huge deal on a street car?)

- Likely fewer pad choices with the LS1 setup.

- LS1 & C5 share the same piston diameter. C6 slightly smaller piston dia as I recall.

- The C5/6 rear caliper will bolt up to the LS1 pad abutment, but you might need to modify the anti-rattle spring. Other than that, a direct swap.

I'm talking about a Chev C-clip axle. I assume the Pontiac axle with the retained bearing would be slightly different.

Sorry for the interruption - carry on!

[modular93fox]

The axle flange pattern is different for us 10 bolt truck rear ends. I picked up a 12 bolt at the junk yard today. Going to try camaro rotors to start with.
clint

[khkiley]

Al,

You make a great observation, for anyone that can go with C5/C6 PBR calipers in the rear they should bolt on to the LS1 abutment bracket.

I have C6/Z06 Calipers (overkill of course, with their own problems, but they look good!), they bolt directly to the caliper mounting bracket without an abutment bracket. Also, as you noted, having the ability to use C5/C6 hardware opens up more options like using z51 abutments for larger rotors.

Its good to mention the direct use of the LS1 hardware for those that can use it.

Kurt

[khkiley]

Clint,

My C6/Z06 Calipers (without abutment) are threaded, so I assume c5/c6 abutments are threaded. My C5 steering knuckles are not threaded.

Kurt

[khkiley]

Fabian,

Did you bolt your caliper brackets to the axle flange ? It looks so from the picture. Did you machine off the caliper bracket from the LS1 bracket ? How did you decide between the LS1 bracket and the S10 bracket for your setup ?

Kurt

[liquidh8]

aren't the c5-c6 rotor slimmer than the LS1 Camaro's? the LS somewhere around 2.45 total height, and the Vette closer to 2? This could help out if you have a clearance issue with the frame rails. pushing the calipers out almost 1/2 inch.

This is something I am in the process of doing for my G-body, with a 9". trying to get s-10/LS1 ebrake, and then the 12" LS or C5 rotors and PBR calipers. Bracketry is a non issue for me.

[monteboy84]

I'm in the process of doing this now, but I'm using LS1 bracketry and rotors (including internal parking brake) with C5 calipers and pads. I'm starting the installation on my housing this weekend, but I won't be all done til the following weekend. I'll be sure to get plenty of pictures to show how everything fits together.

-matt

ETA: I have a C5 rear rotor at home and my LS1 rotors should be there, so I'll try to get some pics showing the differences.

[modular93fox]

I finished the conversion a while back on my 10 gm 10 bolt (truck)... I made an extra set for my friends 10 bolt (car)

https://static1.pt-content.com/images/pt/2011/02/53149172-1.jpg

https://static1.pt-content.com/images/pt/2011/03/c5bracketkit160-1.jpg

clint

[liquidh8]

I got the s10 brackets today, bu they aren't going to work out with 9"inch. the s10 used a rotor that is 2.9 inches wide. I need to use 2.5 inches. Unless I could use the s10 caliper and abutment, which barely goes on the LS rotor. the LS rotor is 1" thick, the s10 is .8 something. Anyone have any thoughts? looks like I am in the market for LS style backing plates/calipers and abutments.

[modular93fox]

Do the ford 9" housing ends have the same bolt pattern as the camaros? or do you have a custom axle housing end? other wise you could just make your own adapter bracket from axle flange to caliper abutment.
clint

[liquidh8]

Clint, they are the big bearing ford ends. I bought the housing new unused from a guy a few years ago. If I were to get one from the manufacturer, I would have got chevy ends or something. I can fab the bracket, but sine I am trying to keep the ebrake, mounting the ebrake behind the flange is too far away, and on the wheel side it is too close. I think I will give it a week and see if I can locate some LS1 stuff, and sell the S10

[modular93fox]

https://static1.pt-content.com/images/pt/2011/03/1106101-1.jpg

So if you mounted the main bracket behind the axle... depending if it will work with caliper mounting, could you space the parking brake assembly to the correct spacing? In my case I used 2 spacers to get the e-brake assembly inside the rotor... all else fails, Tobin is the man and has a kit for you. A fellow on 67-72chevytrucks.com bought a kit that fit his 9".
clint

[liquidh8]

I had thought about that too. I was gonna make an adapter out of 1/4 plate, hack up the ebrake backing plate so i can get the lever part out of it, than graft it to the adapter. this would allow me to space the ebrake ring mounting point to the inside of the rotor. alot of work thought for the s10 11.6 inch rotor. I'll hold off a few days or so and try and get the LS set-up.

[94MI9C1]

Well I personally got some great advice from this forum when trying to setup my C6 Z06 setup on my car, kindof out of the ordinary 94 Chevy Caprice, and I wanted to offer up what I found as a solution to the parking brake issue. I contacted Tobin, the plethora of knowledge that he is, offered great advice and shared information that he didn't have to, I wish there was more people like him out there. Anyway. I am running the complete C6 GrandSport setup on my car, well not running yet but getting to the final stages of it. I bought Tobins, front bracket and hub assembly and for the rear I contacted him later to see if I could get his bracket for the 10/12 GM axle that he sells. I had a bunch of ideas in my head on how to make it work, a handful of OEM backing plates and all that nonsense. What I am about to show you made complete sense and is fully functioning.

With Tobin's rear bracket in place, I took my factory caprice backing plate and modified it so the ears of the C6 Calipers would clear. I also had to modify the driver's side more than the passenger as the leg for the parking brake cable was in the way, so I cut it off and later made a bracket to bolt it to Tobin's caliper brackets. I then made a two piece shim out of 3/16's plate that rides in between the backing plate and Kore3's bracket. You will get the idea from the pictures.

I didn't think to take pictures of the backing plates side by side, note on the 94-96 caprice and impala rear disc backing plates the parking brake cable hold down tab is on the top and facing rear on the passenger and on the bottom facing forward on the drivers side.
This picture is the driver's side with the cable ear already cut off and it is marking up for trimming for the caliper ears to fit, this should be the same if going with C5 style brakes as well.
https://static1.pt-content.com/images/pt/2011/06/IMAG0124-1.jpg

Also with this I relocated the calipers to the front of the differential instead of the rear like factory.

I had to weld in studs to the backing plates, as it would be near impossible to hold the hold down bolts to tighten them, here is the passenger side all trimmed up and ready to go
https://static1.pt-content.com/images/pt/2011/06/IMG_2833-1.jpg

Here is the split spacer that I was talking about above, I originally made it out of 1/4 inch plate, but after final assembly it was too thick, so I made it from 3/16's

https://static1.pt-content.com/images/pt/2011/06/IMG_2832-1.jpg

Here is the drivers side so that you can see the component stack up

https://static1.pt-content.com/images/pt/2011/06/IMG_2837-1.jpg

Passenger side
https://static1.pt-content.com/images/pt/2011/06/IMG_2840-1.jpg
https://static1.pt-content.com/images/pt/2011/06/IMG_2841-1.jpg
https://static1.pt-content.com/images/pt/2011/06/IMG_2842-1.jpg


Here is the bracket that I had to make for the parking cable on the drivers side, don't mind the hardware just there for mock up. :)
https://static1.pt-content.com/images/pt/2011/06/IMG_2848-1.jpg



There you have it a fully functioning parking brake assembly and corvette brake setup. I don't think that I missed anything. Kore3 makes a killer parking brake kit, I just didn't have the money to complete it all and have it functioning. I tried to get a hold of Tobin to gain his approval, but he maybe out somewhere tearing up the streets or something :) Tobin if you read this I greatly appreciate all of your help with this.

Final pic, I put C6 Z06 rims on my car as well. 19X12's in the back with 325/30/19's Hope this information helps someone out. If I missed something let me know. And again not I haven't fully tested this just up on jackstands as I am waiting for another master cylinder to come in to completely test it on the road, including parking brake function. IT locks up the wheels on the jackstands, well one at a time I had to get different cables, but it should all work perfectly.

OP- not trying to clog your thread up, but I figured it was a good place to put this.
https://static1.pt-content.com/images/pt/2011/06/IMG_2879-1.jpg

A shot of the fronts
https://static1.pt-content.com/images/pt/2011/06/IMAG0132-1.jpg

[khkiley]

A lot a people will put your contribution to good use!

Kurt

[94MI9C1]

Kurt, Thanks! I was going to start a new thread about this and I guess that I probably should, not to clog yours you know. I figured there were a ton of threads out there about this and everything so I would pick the one that is most feasible. I figured out a way to make the 4WD S10 backing plates work with this setup as well, but there was some machine work that had to be done and my CNC guy didn't have the time or should I say couldn't get the stuff done in my time frame. I will start a new thread tonight sometime, I have to put this new master cylinder on and see what happens, funny how that works, you get a supposed to be new master cylinder and it won't provide any pressure, go figure.

I even thought about getting new backing plates, doing the machining needed, working with Tobin on the brackets needed and make a somewhat of a kit, but it would probably be a lot of time and effort, plus the liability of someone installing something wrong and have something happen, I wouldn't want that on my conscious. But really if there is interest I can see what the cost would be to get some stuff made, I already have a different idea for the spacer ;) Take care.

Mike

[khkiley]

Its cool, I think its a good idea to keep it in one thread, and if you are going to post some information about the S10 brackets please post it here.

I purchased a set of the S10 brackets and hope to try them out sometime...

Its interesting, I have a full set of GS brakes I will be using as well.

Keep up the good work!

Kurt

[94MI9C1]

Yeah that is pretty interesting. As far as the S10 brackets, I will have to see if I can finally get something made up, I kindof dropped the idea when I figured out how to use my factory backing plates. But it is about the same concept, you have to make a shim, but for those it is going to be about .90 inches it is also going to have to be pretty damn beefy since the calipers would mount to the backing plate, after you modify it of course by cutting the ears off and making a bracket for them. Essentially you have to extend the mounting face of the housing .90 and you will be golden, but you will have to make it removable to install C-clips, etc. I will see what I can get figured out more and send you some information, when I have the time, just swamped right now :)

[chuckd71]

I'm in the process of doing this now, but I'm using LS1 bracketry and rotors (including internal parking brake) with C5 calipers and pads. I'm starting the installation on my housing this weekend, but I won't be all done til the following weekend. I'll be sure to get plenty of pictures to show how everything fits together.

Any update?

[drb930]

I finished the conversion a while back on my 10 gm 10 bolt (truck)... I made an extra set for my friends 10 bolt (car)

https://static1.pt-content.com/images/pt/2011/02/53149172-1.jpg

https://static1.pt-content.com/images/pt/2011/03/c5bracketkit160-1.jpg

clint

Clint,

Did you ever decide to make any more of these brackets?

Thanks,
Dave