Take a look at the links I posted above of the back of the Baer bracket. The bolt does replace the bump stop.

Baer’s setup spaces the wheel out more then the C4 setup with a stock F-body machined hub. I posted the exact numbers above so we only need to space out the rotor enough to equal Baer’s setup. By spacing the rotor out we can use the same thickness spindle bracket as Baer’s (which has been proven to be strong enough). Baer’s hub sticks out further then ours; I really don't see the problem in spacing the wheel out to then exact same as Baer’s setup.

My brothers car has the Baer setup, it lowered is lowered 2-4 inches depending whatever we feel like setting the weight jacks on and the car runs with 255/50/16 slicks front and back and we did not have wheel rub problems. When we drive with these slicks on the street we sometimes get some rub when turning and hitting bumps.

Baer (PBR) designs some of the brakes for GM. Like the C4 and LS1 setup. Many parts are interchangeable. Baer has already done all the figuring out for us. All we have to do is copy there setup.


It looks like it will work. The weird thing is my spindle seems to be a little different then yours. You seem to have more material around the bump stop.

I still feel we should follow what Baer has already figured out because we know it will work and be safe. The last think I want is driving down the road some kid runs out or a deer I slam on my brakes and have the calipers snap off the spindle because of a stress fracture.

 

That's what I needed to see in those pics, Luke. I see where the head of the bolt replaces the steering stop, and all is well for my applications.

I also see the point of the 3 bolt bracket design. The lower bolt would hold both pieces together and in theory keep the factory steering stop. However, I say we just use the Baer bracket design for a few reasons.

One, it's proven to work.

Two, the bolt does in fact replace the steering stop and I don't think anything but an EXTREME hard turn or accident in that area would bend the bracket. If that is a concern, I recommend buying/making 2 or three sets and have an extra set handy wherever you go.

Three, "we" already have a Baer setup handy (IE- Luke's brother) so let's just get the dimentions of that bracket for machining and get this stuff rolling.

Four, we can go with the 1LE spindle design mods minus the steering stop which is only one more cut with a saw.

Rebuttals and opinions are welcomed.



Ed

 

I already got the bracket put in CAD. In my earlier replies I talk about how the stock Baer bracket will not work with the C4 setup because the Baer caliper carrier has its mounting holes extended lower. I fixed this problem by measuring the difference in the carries and moving the mounting holes over by that exact amount in CAD. I tested the new bracket design and it works.

 

Yeah, that's what I meant. I forgot you had to move the holes a little. There's a LOT of info in this here thread and I forgot that.

So when you get it into CAD we'll have the "right" dimentions.


Thanks again.

Ed

 

Stock bear bracket.... This will not work with the C4 setup

 

Modified bracket that will work with the c4 brakes

Hole sizes, from upper most hole to bottom:
Top Right - Spindle mount hole: 1/2 inch (12mm x 1.75 bolt)
Top Left - Caliper mount hole: 37/64 inch
Bottom Left - Spindle hole: 1/2 inch (12mm x 1.75 bolt)
Bottom Right - Caliper mount hole: 37/64 inch

I will get the caliper bolt size when I go to the auto parts store

 

That's a nice print. Do you have the CAD file for it? It would be much easier to use the CAD file to make the part instead of programming it off the print.

If you have the file, I would appreciate a copy of it.

alloy@pcez.com

 

Wow, let me just say that i've been lurking around following this project and i must say that since i've registered here this is the most intuitive and beneficial project i've been aware of.

Especially with the way the board has been going the last couple years imo

i applaud all your efforts and when my car is back together i plan to do this modification and i really appreciate all that you two have accomplished.

i just thought youd like to hear some appreciation

 

So Alloy,

What do you estimate the cost of these things to be seeing that you're a machinist? I'll donate some funding to the cause if we can get some brackets made, I'm sure selling spare sets of brackets won't be a problem. I'm almost ready to go with this and I have located a set of brakes already.


Ed

 

Yea I need a set made too. Hopefully I can find someplace that will do it for a good deal. But first I need to determine thickness.

Alloy: you have mail. I emailed the bracket CAD file to you.

 

Again, great job guys.


Luke, are you not using the 1/2" thick plate or were you just testing that one?


Let me just get my head straight. For the C4 upgrade, we need non-HD brakes from the years 1988-1996, correct? I don't want to get the wrong ones.

Thanks.


Ed

 

Well...maybe i can add in some help on this project

I have a friend who's machine shop is doing so well and is CNCing things for me for a pretty good price

all i would need is a some type of template for him to put into his machine and we could churn these out all day long

I'm sure the cost wouldn't be much, maybe $40-$50 a piece

not sure honestly but it should be something around that area

let me know

 

I test fitted my bracket on this funky plastic/cardboard material I have laying around. It is pretty sturdy and very easy to cut and work with. I made this test bracket just to see if the caliper lines up in the right place. Now I need to figure out the proper thickness of the bracket.

Baer’s bracket is made out of 5/16 inch steal. This will probably not fit because Baer’s hub sticks out 1/8 of an inch more then the machined F-body rotor does. Because Baer’s hub sticks out further it moves the rotor out further which gives more room for a thicker adapter bracket like the 5/16 one Baer uses.

This raises another question. What about rotors off other cars like the G-body? Do the have the same “back to hub face” hub dimensions as the F-body? If they have a greater "back to hub face" then that may solve our problem of the rotor being to close in.


yup

 

Update:
It looks like the bracket is going to be 1/4 inch thick. On this site (that has been posted before) they used 1/4 inch steel to mount C4 brakes.

So I could email this guy and see if he has heard any bracket failures.

I really would like to make the bracket the Baer's setups 5/16 thick but this is not going to happen unless I space the rotor or find another GM car that has a hub design rotor that sticks out further.

 

I got the DXF files and they look good. I imported them into Mastercam and it won't be a problem making them.

Now everyone needs to settle on the bracket thickness. It's good to know that your thickness is the same as what I've come up with. But as I said before, 1/4" seems too thin to me for such a big bracket. And considering the bracket is going to be doing double duty as bump stop, 1/4" is too thin. Having an extra set of brackets would be great, but that's added cost and your could be stuck in the middle of nowhere trying to change it out if it gets bent. Granted it's easy to do, but most of the time when I get stranded it's at night an raining

If the rotor were spaced out even 1/8", this would allow me to make the bracket out of 3/8" materail. I would be a lot more comfortable making them this way.

If everyone decides on 3/8" or even 1/2" thick material, then a spacer will be needed to space the rotor out. Is a spacer like this available? Remember the max diameter of the spacer is 5.9" to be able to fit into the C4 rotor.

 

Well when I calculated the differences between the Baer setup and the Stock rotor machined down setup my calculations show that the bracket could only be 3/16 but I felt that is to small so I adding .06 of a inch to make it 1/4 inch thick which would be a better bet even if it offsets the center of the caliper on the rotor by .06 of a inch.

Baer’s bracket is 5/16 thick. We don't need to go any thicker, but overkill is always good for peace of mind. Baer's bracket is already big time overkill. Remember Baer has to design this to be safe so they don't get sued. So I feel comfortable that Baer engineers designed this sturdy enough.

I am no mechanical engineer but the bracket is taking all its stresses in the vertical axis so 1/4 should be plenty strong. If you are worried that the bracket works as a bump stop is going to bend it we can come up with something that will act as a bump stop instead of the bracket.

Can someone who works at an auto parts store measure the difference between some other GM cars rotors. I want to see if some of there other cars had different back to face offsets. If we can find a rotor that sticks out more we can put a bigger bracket in.

 

May seem like a dumb question but what is going to be holding the corvette rotor onto the custom hub? Just the wheel and lugnuts?

 

That's exactly what will be holding the rotor on. It's just like the factory C4 setup. Nothing more is needed to hold the rotor in place.

 

which are the other g-bodies that have the same bolt pattern?

Maybe our best bet would be to go with the 80' cadillac's and caprices that used the 12 in rotors. These may be thicker (back to face) than what we have. Which other cars were using the 12in rotors and single pistons? Wagons?

But, I can't remember the years but when it stops raining today or tommorow I'll go to a yard and check it out.

Best bet would be to find (as luke said) someone that works at a parts house.

 

The bolt pattern is the least of our worries. A different pattern can easily be drilled on a rotor by any competent machine shop. The biggest thing is the rotor diameter and offset.
I picked up my rear calipers and rotors off a 98 camaro and the rotor has about 1/8 more offset to the outside than the C4 front rotors do which is perfect, but unfortunately they aren't 12" in diameter. I was hoping I'd found our answer in these rotors, but it was not to be I guess.

Anyway I've almost got my C4 setup completed. I'll post pics today or tomorrow.

FYI-Here is a pic of my C4 calipers. I've cleaned one with wire a brush and some Eagle one wheel cleaner. All it took was a little time and elbow grease to get it looking like this.

 

Ok, just finished my right side setup. And yes, I know I have the left caliper on the right side. I ran out of Eagle 1 cleaner before I finished cleaning the right side caliper for the pics.

Anyway this is my 3 bolt setup. You can see that where the 14mm bolt goes through the bottom part of the spindle there is plenty of material around the bolt to prevent it from cracking or breaking out. The bump stop is also fully intact.

Hopefully I'll get everything installed on my car this weekend. I've got a wedding to go to, but am going to try and get out of it. I'd rather work on my car and get the new brakes installed

 

Nice work on the bracket and idea looks really good. Did you decide to go with the 3 bolt bracket because you couldn’t squeeze a 5/16 (Bear’s bracket thickness) bracket in with my bracket design? I hope you post bracket dimensions.

I am going to try and get my hands on some LS1 brakes to see if I can get that swap worked out too. I think I am ultimately going to go with the LS1 brake setup because it has more pad surface area and a thicker rotor then the C4 setup or 1LE setup.

Also has anyone measured the size of any other GM rotors that have a hub built in? I wonder if the G-body has different offsets. I’ll try and see if the guys at the part store will let me open a new g-body rotor box and measure it.

 

Thanks for the compliment. It was a team effrot in my opinion. You had the original idea, and I just had the ability and resources to carry it through to the end. So I'm just a small part of this and I have to thank you for all your hard work on this and giving me the idea.

I've been thinking how we could make a substitute bump stop like you mentioned with the bear type of design, and haven't come up with an answer yet, so I continued with the 3 bolt design just in case.

Another reason I went this was is I still think that for such a big bracket like the one bear uses, 1/4" is pretty thin material. In my design 1/4" is more than adequate since there is such a short distance between the top caliper mounting bolt and the bolt that goes into the spindle. There is almost no chance of it ever bending since the distance is so short between the two top mounting points. Not to mention the 3 bolt bracket is much lighter since it so much smaller. Basically I just tried to make it as simple and strong as possible.

Since everyone has been such a help on this, I'd be glad to post dimensions for the bracket. My software won't dimension a print like ACAD does, but I can try and work something out.

But without a milling machine with a digital readout, or a CNC machine it will be difficult to for anyone get the holes located in the proper places. There isn't much room for error when drilling the holes for the caliper holder.

I've got a system worked out to modify the spindle, and just need to get a left side spindle and take some pics and write up some instructions on the modifacation process. It's pretty easy actually. The biggest hurtle is you will need a 9/16" drill bit for the lower mounting bolt. And it was somewhat difficult for me to find the proper length allen bolts, but I have found a supplier for them now and if people want to buy the brackets from me I'll include the bolts with the brackets. This should make the process a little easier.

Something else I might mention is my used rotors I bought are at mininum thickness and I couldn't get anyone to turn them. I don't think they need it, but I wanted to start out with a nice fresh clean surface on them just because. But I ended up putting them in my lathe and sanding them instead. The have almost zero runout, so I think they will be just fine. So check the thickness before laying down your hard earned cash for used rotors.

 

If you don't mind can you send me that file, it's in DXF format right? If so I can put it in AutoCAD and make dimensions of the bracket.


Why didn’t you use the stock C4 bolts? Did you not get them with your C4 setup? You can buy them from the dealer for a few bucks.

 

If you look at the pics I posted, the upper bolt needs to be an allen head for clearence reasons. A hex head won't work. The other reason is the stock bolts weren't the correct length. What's needed is a 25mm for the top, and a 40mm for the bottom. The bottom could be a hex head, but I wanted not to have to grab different tools to change my pads out. Besides, I was already there getting the 25mm long bolts anyway. They aren't expensive, just had to drive to a fair distance to get the ones I needed.

I figure if I sell these brackets I'll include as much little stuff as I can to make the swap as painless as possible. I hate buying something and then having to go 5 miles to get a washer or cotter pin that could have been included with the part for a few bucks more.

I'll see what I can do on the file. I'm pretty swamped now. I make billet ATV parts and the big memorial day weekend is only a couple of days away and it's pretty nuts here. I've got about 20 shipments going out today, and half of them are next day.

 

I picked up another old rotor and made it into a hub and discovered something interesting about rotors. They are not all the same. After I modded this "new" rotor and drilled out the wheel stud holes to .500 and pressed my new longer ARP studs in, I mounted it up on my right spindle and sat the whole thing in a 15" wheel I have. (It clears my 15" mag perfectly by the way. We are going to check a stock 15" 3rd gen mag to see if it clears in a few days)

Anyway I got to looking at the caliper holder and with this new hub it was more off center of the rotor that it was before. I first thought about breaking down and making a spacer to offset the rotor out a little, then got to looking at it and realized I could just take a little off the caliper mounting bosses to make up to the different in the new hub I made.

Here is a pic of my caliper and caliper holder. You can see where the fresh looking bare metal is on the holder. This is where I milled off around .1 of material. Works like a charm and my caliper is centered very well over the rotor now. The area I milled off didn't reduce the strength of the caliper holder at all. The bosses stick up quite a bit and removing .1 of material from them won't hurt anything. I like this much better than running a spacer between the rotor and hub.

I'm still going to try and get everything on the car this weeeknd. While I've got it apart I'm going to put in new ball joints and finally install my Del-A-Lum front control arm bushings. I'm not sure with all the normal distractions that I can get all this done this weekend, but I'll try. As soon as it's done I'll let you know how it works. I can't wait to try it out

 

Way to go alloy...I was actually thinking about that earlier (taking some off the boss). Wondering if we could go with 5/16 thick brackets and machine off 1/16 from the bosses to line it up. Is that math ok? Or am I confused?

I know that the 1/4 inch brackets are making some of us squeamish, but, this is the same size brackets that all the guys with 1st gen camaros are using on their c4/c5/ls1/Zo6 brake upgrades (see pic).

Also its is possible to fab a bracket for a 12in LS1 rotor AND LS1 basket and be able to use EITHER LS1, C5, or ZO6 calipers in the LS1 basket. Just something to think about. They are all interchangeable. I can't remember exactly what the diff is b/t the C4 and LS1 rotor (thickness?). We've come so far though already w/ the C4 brackets. And I personally do not have the time to investigate a homemade LS1 bracket, which probably would not be that difficult anyway.

 

Thanks for the compliment. Sounds like we are thinking along the same lines. It's sure nice to have 2 mills and 3 lathes handy when doing this kind of stuff.

I guess you might be able to take that much material off the boss and use 5/16" brackets, but if you run into a hub like I did you will still not have the caliper centered on the rotor. I'm using my 1/4" bracket and had to mill .1 off to get everything to line up correctly. If I went to 5/16" I would have to cut an additional 1/16" off the bosses which would be too much.

Honestly with the design of the bracket I've come up with, there is no need for 5/16" material. 1/4" is more than enough since only the top of the bracket is mounting the caliper holder and it's not doing double duty as a bump stop. I'm almost tempted to use aluminum for the bracket since the two top holes are so close togehter, and the bottom of the bracket is only acting as a spacer. But, I'm going ahead with steel. I just got back with a lenght of steel for the brackets. I can get around 10 sets out of this bar, so sometime next week I'll have 8 or 9 extra sets available. Several local people want to bring their cars over and have me do this swap for them, but if I run out of brackets I can always make more I guess.

I haven't looked at the 4th gen or LS1 front setup yet. I was only able to locate the C4 front calipers and rotors. I did find one C5 front rotor locally, but not a caliper. Todd is making brackets for the C5 setup, although they are quite expensive in my opinion, but still a lot cheaper than a 1LE setup.

I'm also going to try and put 4th gen non LS1 rear disks on my 10 bolt. I have the disk setup and was looking at it last night. It won't be a direct bolt on, nor can you just drill some new holes and bolt the caliper brackets onto the 3rgd gen 10 bolt rear. It will require a complete new bracket design. And I'm not sure how the calipers will line up with the rotors using a flat bracket. I've got to put the carrier and axles back into the rear and check to see how this will all come togehter. If I can get this to work, we can upgrade our cars with both front and rear disks for far less than just a 1LE front disk setup costs.

 

Well looks like I won't be doing much this weekend. Was helping unload a delivery truck and the driver dropped a bar of material on my hand. I don't think it's broken, but it's swollen up pretty bad. So, the install of the parts might just have to wait. I know you were all waiting for my report on how the new brakes worked.

I'll let you know when I can get back to work on this again.

Sorry guys.

 

I am in the same position with my rear brakes (drum). Except my seals (and bearings too prob) are bad. So I think I'm just going to find a 98+ rear w/ disc instead of a) fixing mine and b) having to spend time/money on modifying the current drum bracket to fit disc. I think I can deal with my tires sticking out an extra 1/2 inch per side in exchange for the headache.


I am still not sure what to do about my bracket. I think the 3-bolt idea is great but I'm not exactly clear on how to modify the spindle. It looks like the same as the 1LE mod (w/ the bump stops left as is). I'm confused though on the former dust shield holes:

DO you tap both with 12mm x 1.75?

Or, do you tap the upper hole (bracket only) w/ 12mm X 1.75 and tap the lower hole (bracket + caliper basket) using a bigger tap?


I think the 1/4 inch steel should be just fine. That's odd about the rotor you got. Maybe there was a mix-up at the salvage yard. Who knows? I would much rather shave some off the boss than use a spacer.

 

Alloy,
hope your hand gets better soon. Thanks for the info so far.

Craig

 

The Z06 calipers are not going to mount on the same bracket as the C4 or LS1 brakes. The C5 brakes are 13-inch rotors and different caliper carriers with different offsets on the mounting holes.

LS1 rotors are much thicker then C4 rotors and even thicker then 1LE rotors. Also, the LS1 calipers have more pad surface area. I am in the process of getting my hands on some LS1 brakes, should get them in about 2 weeks. When I get them I will get the swap figured out for them also. I hope that we will be able to use the same bracket but cannot say until I get them.

 

You do not need to design a custom bracket. You can use the same bracket off a 4’Th gen. They only cost like $10-15 each from GM. The disc brake 10-bolt mounting bolt pattern is identical on 3’rd and 4’th generation F-body’s. If you have drum brakes in the rear you can easily modify your drum brake flanges by drilling and cutting them to convert them to a disc brake flange. The process is shown here. https://www.thirdgen.org/newdesign/t...reardisc.shtml

Sorry to hear that man, I hope it gets better soon. That is very ironic though because I also smashed my hand yesterday from falling off a horse. I was also planning one doing a lot of brake swap work this weekend and now I am very limited on what I can do too.

 

I went to the auto parts store today and got some measurements. The 80’s G-body rotor is the exact same part number as the 3’rd gen F-body rotor so they have the exact same offset. I measured a 12 inch caprice rotor that did have more offset but I think it will be way to much. So here are the current rotor offset information if anyone else can measure some other GM rotors with built in hubs I would greatly appreciate it.

Measurements are taken from the back of the hub (Not rotor) to the face where the wheel is mounted:

3’rd gen F-body / 80’s G-Body: 1.79 inches
Bear’s custom hub: 1.91 inches
Caprice 12-inch rotor: 2.11 inches

 

Thanks for the well wishes guys. I guess sh*t happens huh? Hey, did you hurt your right hand? That would be too much of a coincidence if you did. Anyway my neighbor is a nurse and she looked at it and nothing is broken, just badly bruised. Been icing it, but it doesn't help. Hurts like heck about now.

And you are welcome for the info. I'm not just helping you, I'm helping myself also. We all suffer from inadequate front brakes on these cars.

On the rear brakes I have they are not the style shown in the article. They are like 3rd gen rear disks with the PBR calipers. I couldn't find a reasonably priced set of LS1 rear disks. I did find a whole rear for $450 plus a $100 core. The guy was a real jerk about it too, so I told them what they could do with that "rear". Anyway it will definitely require custom brackets for the brakes I got. But, after I get it figured out, we can all have access to cheaper non-LS1 disks for our cars that are a dime a dozen in the yards. The bracket will just take some time to design that's all. The big question is will the offset of the rotor work out on this swap. I'll let you know what I find out.

Ok, on to the C4 front brake subject again. With my 3-bolt design you just tap the top hole (I went with 7/16" x 20 because I had a 6" long pulley tap I could use, and that made it easy to get the hole tapped straight). I'll explain this with a description now, and when I can use my hand again I'll got get the left side spindle and take pics of how this is done.

Ok, here is the description of how I've worked the mods out.

First thing you do is you cut the top of the spindle like the 1LE mod. (Do not cut the bottom of the spindle yet) Then you tap the top hole. After you tap the top hole, you bolt my bracket on using the top bolt hole you just drilled and tapped, and bolt the bottom of the bracket on using a 8mm allen in the stock bottom dust shield hole using a allen bolt I'll supply with the brackets. You do this to locate the bracket in the correct position, and then you use the bottom bracket hole as a guide to drill the 9/16" hole for the bottom caliper mount. This hole is just a through hole for the bottom caliper mounting bolt. It does not need to be tapped. The threads in the caliper holder itself. While you have the bracket bolted on you use the bottom of the bracket to mark where you cut the bottom of the spindle. Just cut it flush with the bracket and round the corners off. After the hole is drilled and the spindle is cut, you remove and discard the 8mm allen and bolt. There is no further use for it. And you do not need to do anything with the bottom dust shield hole. You only use it to locate the bracket for drilling and marking the spindle cut line.

After that you simply put the modified rotor (now a hub) on and bolt in the caliper using the two 14mm bolts that will come with the bracket. Also, you must replace your stock wheel studs with longer ones. I used ARP#100-7708 that I bought from Jegs. The knurl diameter is .509 on these studs, and that was too much of a press to put in the .484 hole that the stock studs were in on my hubs. So I drilled out the holes to .500 (1/2") and the studs were a medium press fit with my 2-ton arbor press.

You must replace these studs. There is no getting around this. Please don't try to get by with the stock studs. They are too short with the rotor deducting 3/16" of length on them. Besides even if you have a 1992 car, your studs are 11 years old. Not a bad idea to replace them anyway. Especially for performance work.

Now depending on what offset your hubs are, you may have to machine the boss down like I did. And, there was no mix-up at the wrecking yard on the hubs. I pulled the spindle and rotor of an 86 TA myself, so I know they are correct. Looking at the dimension of the baer hub, there is only .12 difference between them and our hubs. We can easily make this different up by machining the caliper bosses down. And, this was pretty easy for me to do, but another shop might charge you a small fortune to do this. The reason is I had to devise a special setup to hold the caliper holders in my milling vise. Took about an hour to get it worked out, but that's $60 if you pay a shop to do it. I've got my fixture made up now so it only take about 20 minutes to set up on these and about 15 min each to mill them off. A thin spacer might be cheaper, but my machining center was tied up running other stuff and that's the machine I'd use to make a spacer out of. So after I figured this out, I did this on my manual mill instead. Works great! I'd much rather do this than run a spacer.

Well my hand feels like it's on fire, so I'm going to get off this thing and go put some more ice on it. Hope everyone has a great weekend!

 

You are talking about the 93-97 F-body rear brakes right? These brakes do not need a custom bracket. You can use the bracket off the same car that you got the brakes off of and it will all mount right up to your thirdgen (unless you have a 9-bolt rear). You can also buy these brackets from a GM dealer for very cheap. All F-body disc brake setups from 1984-2002 have the exact same mounting bolt pattern on the rear housing so the setup can be mounted on any 10-bolt disc rear from 84-2002 (will not work on the 9-bolt rearends). The link I posted is just to show how to modify the flange on your rearend if you have a drum brake rearend. The drum brake rears have different flanges then the disc brakes rears. Just wanted to clear that up, maybe save you some time designing a bracket.


Question about the 3 bolt design bracket.
The lower hole on the caliper carrier mounts below the machined flat dust shield hole on the spindle right? It looks like it mounts to the unsmooth part of the spindle. Did you machine this area down on the spindle to create a flat mounting surface?


I started writing a tech article on how to do this swap if I end up using my bracket design the article will still include how to do the swap with both Alloy’s and my bracket designs.

 

On the rear brakes I have there is no way there is enough material to just drill the flange and make it work. It's a different setup than the one in the article. I have the brackets and when you put them up to the axle flange if you drilled through, you would not hit solid material on the bottom of the axle flange like the article shows, and the top is only about .02 from breaking through the edge of the axle flange.

I suspect these are 98 and up rear brakes. If the 97 and down bracket will work on 98 and up calipers then I'm set if they have a narrower bolt pattern. But if they all have the same pattern as you say, then for this set of brakes I have I'll have to make a bracket for them.

On the spindle I've taken a pic where the bottom bolt goes. The area isn't completely smooth. But it's smooth about 3/4 of the way around and when you tighten the bracket it lays perfectly flat. I'm very comfortable with this setup.

My pic of this part of the spindle is kinda blurry. It's hard to hold my camera steady with no grip to speak of in my right hand.

 

Off subject: I'm a 3rd year medical student. What did you do to your hand and how did you do it?

Any burning, tingling, weakness? If so, is it your entire hand or just the top right or left? or palm right or left?

Any history of injuring your hand?

What have you used that makes it better? that makes it worse?

What limitations to movement/use do you have now in your hand?

 

We were unloading 4" aluminum bar stock and the driver dropped the bar from about 2' while I was holding onto the other end. I let go but it bounced up and hit the back of my right hand above the knuckles.

I didn't expect the guy to drop the bar like that. I'm pretty carefull with these bars since the product I make out if them is only .02 less that 4'. And if there are any deep scars in the bar it will show up in the part. I've alse run my machine shop since 89 without even 1 accident. To me this wasn't my fault. But, I'm the one hurt and what's done is done.

The back of my hand is just swollen and painfull. I've got good feeling in my fingers, but can't make a fist without a lot of pain. My thumb is totally unaffected. I have full movement and strength of my thumb. Other than the normal history of a 45 year old gear head busting his knuckles on cars for 30 years, no major injuries to the hand. It will just take time to heal I guess.

Anyway I really appreciate your concern. Thanks!

Wow, a med student huh? Great job! Hey, do 3rd gen owners get a discount after you get out of med school

Just kidding. But still a great job on your part. Very nice going!!!!

 

Yep Alloy, anything for a fellow thirdgenner!

The guidance on the braking system alterations is worth a discount for sure! Great work! Is a tech article in the works?

 

As said above, I am in the process of making it. I will include the following in the article:

- How the swap came about
- Part numbers and parts needed
- 1LE proportion valve and master cylinder section (which is needed for this swap)
- Information on the alloys bracket kit
- How to modify the spindle for alloys bracket
- How to modify it if you are using my bracket design
- How to make a hub out of an old F-Body/G-body rotor
- How to mount LS1 brakes (once I get them, their in the mail)
....and much, much more

 

Hey alloy, for you I am sure Dr G and I can work in free rectal exams.

...sounds like tendintitis. Just keep icing it and take some motrin. If its still hurting in a couple of weeks, go see a doc.

I'm so pissed now b/c I really want to get started on this upgrade, but I'm neck deep in licensing exam study material. AHhh. The nightmare never ends.

This entire mod is nearly squared away it looks like. Just a few minor details to clear up and a tech article for 89IROCZ to write.

I do have an important question though about used C4 rotors. What is the safest minimum rotor thickness of a salvage yard rotor? What other 'red flags' are important to look for with salvage yard rotors?

 

Geez, free rectal exams huh? :nono: Boy, I thought I was helping you guys out with this brake upgrade Thanks a lot. With friends like you guys, who the heck needs enemies!

I may have to "re think" my position on this deal

The min. thickness of a C4 front rotor is 18.4 mm, or .7245 in. You can pick up one of those cheap nylon dial calipers, or a cheap micrometer to take with you when picking up rotors to measure them. You probably won't be able to tell with just a tape measure. Mine look good, but as I said they are at min. thickness.

For red flags to look for I guess look for signs of the rotor overheating and heat checking, (cracking like on a flywheel with a burned up clutch) and deep wear grooves.

Has anyone thought to check out the rear rotors of a C4 yet? I'm not sure if they have the parking brake drums inside the rear rotor like and LS1 rear setup or not, but the offset just might be different. Might save having to find a shop to mill the caliper carrier bosses off.

As far as a tech article goes, I'll help with any info and pics needed to get this accomplished. When I get my bracket kits made up, I'll include step by step instructions and pics to show how the spindle and rotor need to be modded. Hopefully whatever machine shop you guys take your rotors to for them to be modified will not be "know it alls" and will look and listen to what you have to show them. They won't have a clue as to what you are talking about and probably will be reluctant to do the work for liability reasons. And they might not be as well set up for this specific type of work as we are, so expect to pay the price for special setups or fixtures. So before diving into this, check on pricing for the machine work in your area. I can do the work for you guys, but UPS costs will definatly add to the cost of the swap. So please do your homework first before committing to this.


Anyway as far as my weekend goes I'm in kinda the same boat as you. I want to get working on this but here I sit with a chunk of unusable meat for a right hand. Sure makes me appreciate what Bob Dole goes through everyday of his life now.

 

I don't know Alloy, you know you've got to get that prostate checked yearly after 50. You're close. It might be well worth it financially.

I don't think any of my future patients will like that though on account of my large hands. I'll just give you a good referral, instead.

Thats exactly what I needed to know about the rotors. I'm not sure about the rear C4 rotors. I don't thinks its ever really come up. I think since the 4th gen f-body rear brakes work, nobody has probably bothered to check.

Hey..its been a while since I researched 4th gen rears in general. Is that internal drum parking brake (98+) compatable with 3rd gens, provided you snagged the cable too?

Good luck w/ the getting those orders out for the billet pieces. Let me (us) know when you get around to cranking out brackets. I'll prob order a set as soon as you are ready.

I have a question: What exactly is "billet" steel? I've always wondered.

 

Alloy, I'm with Like here...if those brakes came off a 10 bolt, they should fit your 10 bolt with NO mods necessary. 10 bolt rears are 10 bolt rears and they haven't changed much except for the length. You can get 10 bolt backing plates from Dal for ~ $11 each. Mine were $33 shipped for two. I'm doing a drum to disc conversion like Luke mentioned.

Are you sure the backing plates you are trying to user aren't 9 bolt plates? If the holes don't line up that's what you may have.


Ed

 

Well for now you can just keep those fingers to yourself:nono:

The brakes definately came off a 10 bolt 4rd gen rear. It was not a 9 bolt. But if anyone has the dimension on the bolt pattern I'd appreciate getting the measurements to compare them to what I have here.

If I can't buy brackets or these are off a 9 bolt I'll make the brackets and that will be that. It's not a big deal for me to do this. Shoot, I pay BIG payments on thse machines every month, so I like to be able to use them for something I want to do every once in a while. Geez, half the fun of this for me is adapting and designing things like this.

My hand is getting a little better now. The swelling is going down so I may be able to go get the rest of the parts from the U-Pull-It yard sometime this week for the conversion. The maybe, just maybe fate won't deal me a another blow like this one and I'll get the car together this weekend.

 

Hey, been thinking about his swap and wondered if anyone else has a g-meter or something like that to measure stopping distances.

It would be nice to have a before and after comparision between stock front disks, and the C4 setup. I've been trying to think of a place I could go do some testing of stopping distances with a long tape measure, but can't really think of a place to do it. It would assume you would need to get up to around 50 mph to perform a decent test.

Does anyone else have the ability to measure stopping distances?



I just remembered I didn't answer the question about billet.

Basically making a part from billet means you are making it from a solid peice of material, and not a casting. Billet is much stronger than a casting since the material is extruded (forced) through a hole to the approximate shape and size, then rolled (compressed) to the proper shape. This makes billet more dense and stronger than a casting.

 

Alloy, you asked earlier about the C4 rear rotors. The guy I bought my brakes from threw in the rear rotors also so when I get them next week, I'll post a pic of the front and rears together.


Ed

 

That's great Ed!

I guess we need to know thickness, and the offset of the rotor. And if they have the parking brake drum in them like LS1 rear brakes do.

 

At the streetracing events we put on at the track we use one of those wheel tape measure sticks to mark out car lengths so that the racers can give spots to other cars

i'm sure you could get one for like $20 then just use some cones.

Use the first cone as a signal to begin stopping and then just mark off every 10 feet and put another cone

i'm sure you could borrow the cones from someone

That'd be the easiest way