could i get a copy of that drawing when its done? i would be in your debt. Laiky@aol.com

 

Hello,

I am very interested in getting moving on a brake upgrade. Has anyone come up with the correct dimensions for a caliper adapter braket and hub dimensions.

All to use 12" non-hd vette rotors on a stock third gen spindle.

I see talk of a dimensioned drawing... I dream of a copy.

Take it Easy,
Gus

 

Dude..gotta ask you; How did you figure out that the Baer bracket fits C4 calipers?

Was it b/c the Baer calipers look like C4/LS1 calipers?

 

I'm a little ignorant on this debate, wouldn't regular 1le rotors fit our existing spindles??

 

Yep 1LE rotors will fit, but will not work w/ the c4 calipers. You can get 1LE calipers and 1LE rotors and all the hardware for $850 and up, but we are trying to do a 1LE alternative using C4 calipers, rotors for much less $$.


OK I bought a spindle and rotor today from a salvage yard ($27). Tomorrow I am taking them to a machine shop and have the spindle done 1LE style and have the rotor turned into a hub.

The salvage yard has calipers and rotor from a C4. But I cannot test fit the whole unit until I get a bracket. After machining the hub I guess I'll just test fit the C4 rotor and see.

QUESTIONS:

1) there is a picture of a Baer hub posted above with the measured thickness (from the back to the rotor mounting surface) at 50 cm. This width works with the Baer bracket that we are going to use a template right? So I will have the rotor machined into a hub and then make sure that the width of the machined hub is the same as the Baer hub.

2) Toddlsf showed in a pic that he had to mill that shelf onto the face of the hub to accpet the C5 caliper. Anyone know if this is necessary w/ a C4 caliper? And if Todd would be so kind, what are the dimensions of that "shelf"?

 

Hey, dumb qyestion. Not being a "vette" guy anymore, and not to mention my vette was a 70, is there a difference in brake rotors from front to rear on a c4 vette?

I belive I've found a set of used rear rotors for a good price, but the guy that has them can't tell me if the rears are the same as the fronts.

Also, the rotors we are looking for are off of a 84 to 96 vette right?

 

I test fitted the C4 brakes to the Baer setup today.

The C4 break caliper carrier is about ½ inch shallower where the mounting holes are. So I am going to CAD out the Baer spindle mounting plate. Then measure the difference in the C4 carrier and Baer carrier and move the bolt holes out that exact amount in CAD. Then I should have a perfect fit bracket for the C4 brakes.

 

Dude! You're a friggin champ. Way to be there. No questions about the bracket (I'm sure you're getting that squared away).

But, I would like to know about the hub. Did you just mill it down into a hub w/o any other changes to the face or back?

Thanks again, man.

 

You can see in the picture below why the c4 brakes did not fit on the bear bracket. All that need to be done is move the bolt holes out on the spindle adapter plate.

I am going to measure the difference between the Bear and the C4 caliper carriers and move the mounting holes out that exact amount and then get it machined.

On the left if the C4 caliper carrier. On the right is the Bear caliper carrier.

 

Atta boy Luke!!!! I've been lurking this topic for some time and will be keeping closer tabs on it. I'd like to get better brakes on my RS.


Thanks to all, Luke and all you other guys doing the footwork on this.


Ed

 

I haven't got it milled down yet but you won't have to mill the face of the hub down. Mill your hub like how “toddlsf” did it and you will be fine.

 

Also I am trying to get a hold of some LS1 brakes so I can work out the swap for those too. It should be almost the exact same swap, may need to modify the spindle bracket a little. If anyone knows where I can get LS1 calipers, caliper mounting brackets and rotors for cheap Private Message or email me.

 

yeah Todd's picture is what I'm curious about. I am wondering about that groove that runs the circumfirence of the face. The picture the Monte Carlo guys are using (as posted above as well) does not have that groove. Maybe its because they use a smaller diameter bell (hub).

I saw an LS1 at the salvage yard two days ago. It had complete front brakes still on the car.

I had planned on milling my hub and spindle and assmebling it w/ the bracket and taking it to the yard to test fit both the vette and LS1 caliper/rotors.

I could get over there and take some measurements/pictures if that would be helpful.

Sadly, they are not at the same yard. Otherwise I would compare the two directly just by visual. I'll call the yard who has the vette calipers and see if they have any LS1 calipers laying around.

What would be really great is if there were a member here with both a C4 and an LS1!

I'll call the yard and see. It would be great if the LS1 calipers matched the Baer bracket perfectly.

 

http://ourworld.compuserve.com/homep...es_on_fgen.htm

This link helped alot (although its for 1st gen f-bodies)!

89IROC: Does your brother by chance have the 13in baer setup?
That would explain why his caliper bracket is 'taller' than the C4 bracket. IN fact, if that's the case then a 12in rotor + matching caliper bracket will fit the same adaptor as a 13in rotor + matching caliper bracket. And we won't know for sure until you get that hub milled and fitted w/ a 12 in rotor and attach the C4 caliper bracket.

*** here is the interesting part ***

The guy who wrote the tech page says that he designed the adaptor bracket and that it will work with either a 12 or 13 in rotor ONLY if you use a matching caliper brackets (i.e C4 caliper w/12 in rotor OR C5 caliper w/ 13in rotor).

Based on that, I think we may be able to use the already desgined/ fabricated adaptor that Toddlsf created for a C5 setup and use it for our C4 setup w/ no problem.

Think about this for a little bit. Would be really nice if Todd would "LOAN" you a bracket so we could test fit it.

 

I don’t think the C5 caliper mounting bracket is going to come anywhere close to working. The C5 brakes are a 13 setup. Here’s why the C4 12 and 13 inch brakes can be mounted on the same bracket. GM designed a different carrier for the 13 C4 setup with mounting holes that extend farter out. That way they could use the same C4 spindle for either setup.

My brothers Baer setup is a 12 inch. I think Baer used the C4 13 inch caliper carrier (which the mounting holes extent further out, as you can see above) on there 12 inch setups (there interchangeable on the calipers). The only reason I could think for doing this would be to minimize the size of the spindle mounting bracket. The more the spindle mounting bracket is extended out the more stress on it and the more probability for it to fail.

 

So basically it seems like Baer used a 13 in caliper carrier and just mounted it on a shorter bracket to accomodate a 12 in rotor. So I am guessing that your C4 caliper was already hitting the top of the rotor an inch or so before you could get the C4 caliper carrier lined up on the bracket.


Here is my logical train of thought:

What if Baer mounted that 13 in caliper carrier on a bracket designed for a 13 in rotor. Using a 13 in rotor, it would be a perfect fit (obviously).

But what if you substituted a 12 inch rotor on the previous 13 in setup? There would be probably an inch between the top of the brake pads and the top of the 12 in rotor. So how to fix? We could either make the bracket 1 inch shorter, we could keep the same size bracket but make the bolt holes 1 inch lower, or make the caliper carrier shorter so that the caliper sits lower.

So with the same exact bracket, you could use a 13in rotor with a taller (i.e. C5) caliper carrier, OR you could use a 12 in rotor with a shorter (i.e C4) caliper carrier. Bolt holes would stay the same.

Who knows? I'm probably completely wrong and this is all just based on wishful thinking. I think I'm just anxious to get this setup on my car b/c I hate my brakes like you wouldn't believe (or actually you probably would). Anyway. Good work.

How is the 2-d autocad coming along?

 

No, because the C5 setup does not have an extended caliper carrier like the C4 13 inch setup. The C5 brakes are not going to mount on the same spindle bracket as the C4 setup.

I am confused how you got a measurement of 1 inch difference from? If you increase a rotor in size by an inch i.e. 12 to 13 inch rotor since it's a circle you are only going to have a fraction of that inch bigger on each side. The Baer spindle mounting bracket is about 1/2 inch or less to shallow.

I suppose if you wanted to you could buy the C4 13 inch caliper carriers from GM and use them to mount your C4 12 inch brakes. But if you have to make a spindle bracket anyways it’s a waste of money, time and effort.

I just feel that you are making something simple way to complicated, or maybe I am interrupting you wrong. All that needs to be done is to measure the difference is space between the Baer and C4 caliper carriers, as seen above. Then move the caliper mounting holes out that exact amount.

My theory has and always will be the simpler something is to make or develop the better. It just makes less complication and cheaper. And since I am a poor college student it’s all about the money. I don’t want to mix and match parts. I want it to be a simple as go buy a 12 inch C4 brake setup, make this simple spindle bracket from a template you can print out, machine a hub, and follow my tech article (which will be made when I complete the swap) and your done.

 

I was just about to admit defeat even before I read your post.

I did some searching and noticed (as you stated) that GM did not use an extended mounting bracket on the C5. For some reason I thought they had kept the same bracket and used a different caliper carrier.

Although it seems like I'm making this complicated, I was trying to simplify things by using a bracket that someone here had already designed for a different setup. Oh well. My intentions were good.

True about the rotor diameter (.5 inch). Oops.

I stand corrected.

I think that your method to fit the C4 calipers should work perfectly. I'm really excited to see how this all turns out. Keep me posted.:hail:

 

Well I picked up a used right spindle and a rotor today. Cost me $38 at a u-pull-it yard. I couldn't find a scrap rotor, so ended up paying for the spindle, core charge for the spindle, and $10 for the rotor. But, I did find a good set of 12" C4 rotors and a set of calipers for $120 at another yard. They are going to pull them on Monday and I can pick them up on Tuesday.

I also modified the rotor. Here are pics of the "chain drilling" I spoke about in an earlier post. I used my drill press and a 1/4" drill bit on my little drill press. Took me about 20 minutes to drill around the rotor as shown. After I finished the drilling I took a sharp cold chisel and hit between the holes I drilled. I got about 15 of the holes broken out between them and the whole rotor section just dropped off. Very easy to do this way.

Then I chucked up the hub section on my engine lathe and turned the remants of the chain drilling off. Took a me few minutes and had cast iron dust flying everywhere. But it worked pretty well and the results are not too bad. If someone brought rotors into me drilled off like I did mine, I'd machine the rotors for $60 per pair. So this gives you an idea of what a shop would charge you for this.

I've posted pics of the chain drilling, and the lathe work. The last pic is of my setup on the lathe in case you anyone needs to take a pic to a shop to show them how to do set the rotor up easily.

Hopefully I'll have time to go pick up the vette rotors and calipers on Tuesday and start making my own brackets. If the dimensions are posted before then that would speed things along nicely. If not, then I'll figure it out myself and program the brackets up and run a few sets on my machining center.

If you have any questions on the rotor mod, just let me know.

 

Once this never ending rain stops here. I am going to take the spindle bracket off my brother’s car and get the dimensions off it. Then move the holes out as necessary and post the finial bracket design. I should have the final bracket design before the end of next week.

 

Sweet pics alloy. I have access to a drill press, Ill do the same and save some money . Thanks for the nice pics.

 

i am literally on the edge of my seat!!! what do you think the final cost of this upgrade will be using used parts??

 

You are welcome for the pics. I'm just trying to be of help on this and not just mooch of others work. After all someone else is going to make up the bracket drawing for all of us, so I'm just trying to do my part.

Cost??? Well it depends on a number of factors. Can you do any of the work yourself, can you find the rotors and calipers for a decent price, and will the machine shop that modifies your rotors charge you an arm and a leg. Also depends on the cost of the brackets. For me I'm going to have $130 in the vette rotors and calipers, $80 in extra spindles and rotors, $$$ ??? for brake pads, and some time and material in the brackets I'll be making to mount the calipers.

Since I have a machining center, and a manual lathe and can make my own brackets and machine the rotors I'll have about $250 in the whole thing. I would guess you should add about $200 more if you paid for the brackets and rotor mods. So best guess would be about $450 if you can install the parts on the car yourself. (I could cut my cost $80 for the extra spindles and rotors, but I want to be able to drive the car while I'm doing the work to the parts).

Rotor update:

After I thought I'd finished with the rotor, I realized I wasn't quite finished yet. In looking at the rotor I realized there was extra material on the back of the new "hub" that served no purpose. So, here is a pic of the ring of material I removed.

When I started this second operation on the rotor, it was 1.47 wide from the face of where the wheel sits on to the back where I'd cut the rotor off. After machining (again) it's now down to .6 wide. The rotor also weighs 1 1/4" pounds less after I removed the extra "ring" of materail. That's a substantial weight difference in unsprung weight.

Here is a pic of what I'm talking about.

 

Update:

You do not need to machine the face of the hub as seen in the pic by "toddlsf". The C4 rotor slides right over it. You may have to do so for the LS1 brakes.

 

This is great material. I have a set of extra spindles and stock rotors. I just need to find the corvette parts and I'm more than half way there. Thanks for the info.
Kory

 

Try www.car-part.com for the rotors and calipers. That's where I found mine.

I used 1992 for a year, and the clicked the 12" rotor option. Also used pacific northwest for the area. Found a yard that had them about 100 miles away. But they have another yard about 15 miles from me and they do yard transfers every other day. So they are shipping them to Portland on their truck and I'll pick the up there.

Cost was $130 for both the rotors and calipers. They have more, but shipping might cost might be prohibitive if you aren't local to them.

 

Thats cool I'll check them out.
Thanks,
Kory

 

Excellent pics Alloy!!!! Good call on removing the extra material. That will lighten the hub up a lot.

Did anyone else notice that the caliper was installed UPSIDE DOWN with the bleeder screw at the bottom???? Good luck bleeding that bad boy....


Ed

 

Ok, Huston we have a problem.

Has anyone else besides me gotten their calipers and rotors and tried to fit them to the spindle to mock up a bracket yet??? Someone please tell me you have, and have solved the problem I've run into.

Ok, heres the deal. I modified my extra spindle per the 1LE instructions this last weekend, and thought for a second time I'd finished machining my rotor "hub". I picked up the rotors and calipers when I was picking up some other stuff for my business this afternoon, and rushed back to my shop to test fit them onto my spindle and hub after work.

First problem I ran into. The new hub I machined up wouldn't fit down into the C4 rotor. After doing some measuring my hub OD was 6.33. In the C4 rotor you could look into the back of it and see the imprint of the vette hub. The imprint was 5.7 in diameter. So, after looking at it and realizing that the vettes have the same bolt pattern for the wheels and have a 5.7 OD hub, I decided to machine my hub OD down. I went to 5.75 which is a little too much. I broke into the balancing holes that were drilled into the back of the hub. I should have went to 5.9 which would have been sufficent to fit into the rotor just fine. It will work this way, but I'd rather of not broken into those holes.

Ok, next problem. The hole pattern on the C4 caliper bracket is wider than the stock 1LE bracket. So, as the old saying goes, a pic is worth a thousand words.

Take a look at the relationship of the caliper bracket holes and the mounting holes I'd planned to use for the caliper bracket "mounting bracket". As you can see they are very close together and it's impossible to use a bracket like the one in the pics todd showed us. If you use a larger rotor and space the caliper out .5, then you are golden. But for a 12" rotor it won't work.

I have an idea on a way to cure this, but I need another spindle to hack up. Unfortunately I don't have time during the week days to go get another spindle. My weekends are my only time free, and this weekend is booked for me with a 2 day autocross event.

So if anyone has any idea on this I'm all ears. And, if you haven't modified your spindles yet, hold off on doing it. I just may have an idea that might work, but won't work with a spindle modified to 1LE specs.

 

Baer’s hub is 5.95 inches. I would just copy that.

Look at my very first post in this thread. You will see how the spindle bracket needs to be made to position the caliper. The bracket is not a problem. Baer already solved that problem for us. You have to rotate the caliper. It is not going to be mounted in the stock position.

The bracket I designed by moving the mounting holes of the Baer spindle bracket out to compensate for the different offsets in the caliper carriers.

 

Well I've looked at the pic many times today, and have tried rotating the caliper and it just doesn't look like it will work.

But, I'm the first to admit I do not know everything and definately want to see the bracket you have designed up. If it's in a CAD drawing or if you can shoot me a DXF file, I'll make one up out of some scrap aluminum (easy to machine, don't have to clean my machine out to run steel, and I've got literally tons of aluminum here to use for this). And after I make one up I'll post pics of it for all to see.

One thing that would help is a pic of the back side of the spindle with the baer bracket bolted to it.

Oh, and guys, when you get your rotors and calipers, make sure the wrecking yard doesn't loose the the caliper guide pins. The set I got had 3 out of 4 pins gone, and auto zone wants $38 for a set of 4. Ouch!!! So I'm going to see if I can snag them off another car at the junk yard.

 

Alloy used the '92 C4 brake search at www.car-part.com, but say let's enter '96 as the year and you get all of this crap:


Front, exc. Collector's Edition and Grand Sport Right
Front, exc. Collector's Edition and Grand Sport Left
Front, Collector's Edition Right
Front, Collector's Edition Left
Front, Grand Sport Right
Front, Grand Sport Left


What's all this? Are the Grand Sport and Collector's Edition the 13" pre-C5 brakes? I dunno....



Ed

 

Well I'm not sure either about all the options you came up with. I just used 1992 and clicked on 12" brakes and got what I wanted.

It could be that the 96's with the different perf. packages had different size brakes. I'd just use 1992 and choose 12" rotors.

If you use pacific northwest, B&R Auto Wrecking has more rotors and calipers for sale.

 

I finally finished the bracket design. With thanks to my roommate I got the stock Baer bracket put in AutoCAD then I had him move the mounting holes to compensate for the difference in the caliper carriers. I have to try it first and if it is right I will post the dimensions.

This is what it will look like (not actual size)

 

I've looked at the bracket drawing and mocked up the position of the caliper in relation to the spindle using the approximate position of where your bracket will put it, and somehow I don't think it will work.

Here is a pic of the caliper in the approximate position that the bracket will put it. As you can see on the left side the caliper mounting bolt will require more material to be removed from the spindle. I've placed a bolt where the caliper hole is to show what additional material would need to be removed for bolt clearence.

Also, the bracket thickness can be no more than 1/4" with the parts I have. I've got the caliper centered over the rotor to within .020. So it's pretty darn close.

 

Here’s how I modified mine. I just copied what Baer did to my brother’s spindle and it works well.



BEFORE:

 

AFTER

 

Another After

 

With these new pics it a little more clear to me what they did now.

If you look at your before and after pics, you will see that they removed the entire steering bump stop from the bottom of the spindle. This is entirely different from the 1LE spindle style modifaction. The 1LE mod leaves the stop on the spindle since it doesn't need the clearence for a bolt head, and I modded my spindle per 1LE specs.

I'm not entriely comfortable with removing the bump stop from the spindle. I just took a look and my spindle and the stop on it and the lower a-arm both show a lot of wear on my car. But I do a lot of autocrossing and I'm sure I've hit the stops many times.

So with no steering stop I'm thinking I'd probably rub my race tires pretty badly. Especially with the tires out 5/16" more to towards the outside of the car. (5/16 is the exact thickness of the C4 rotor flange where it slips over the hub) I'm not fond of the thought of tearing something up like this.

Have you taken your brothers car and turned it to full lock and looked under it to see what stops the steering at full left and right? I'm very curiuos to know what hits first.

 

I am not sure what you are talking about, please explain. They way I modified my spindle it shouldn’t affect anything. That nub I removed is not a bump stop.

My brother’s car used to be in a SCCA racer and is excessively lowered with weight jacks. When we put slick on the car they don’t rub much at all.

 

Ok, in the top "before" pic in the lower left corner there is a kind of point sticking down right below the dust sheild mounting hole. This is the steering stop that hits the welded stop on the lower a-arm.

I'll take some pics tomorrow and show you what I mean. I'll have to pull the tire/wheel off to do this, and at 11:44 pm I'm not in the mood to do this now

 

Well the bracket will replace that point sticking out. Because the brake bracket goes exactly where the point or "nub" used to be. So even if it does have a purpose the brake bracket will be there to replace it.

 

Well I test fitted my custom bracket on my brothers car and it works! Now I just need figure out the proper thickness and a cheap place to machine it for me.

 

The two big holes on the bracket are where the caliper mounts. The two smaller holes are where you mount the bracket to the spindle.

Did some more measurements:
Bear hub, back to face: 1.91 inches
Stock rotors machined into hub, back to face: 1.79 inches

If 1/4 inch steal is not strong enough for the bracket then. I will have to put a .12 inch spacer between the rotor and the hub. That could bring the cost up close to a 1LE setup which would be fine for the LS1 setup because it is better then 1LE (thicker rotors, more pad area). But not sure if it would be worth it for the C4 setup.

I’ll try to think of more options.

 

Now it makes sense...the Baer system uses spindles with the hard steering stops cut off, huh? Well phooey. We would have to cut ours off to make use of that bracket design since it puts a bolt right there.


Also, kudos to Luke for getting the bracket to work. Now, if we could just have pics of the BACK of the spindle/bracket since that's where we are having the designing and clearance problems. I would also like to see pics of the rear of that Baer system on your brother's car also, if you could. Is there any way to rotate the caliper any more to avoid the steering stop interference?

Great job guys!!! If this bracket thing becomes an issue, I might as well go ahead and do the C5 brakes instead. The larger rotor and caliper would give the added clearance we are lacking.


Ed

 

There shouldn't be interference, as said in one of my previous replies.

So the point or nub (whatever you want to call it) is being replaced by the bracket so there should be no problems. Also my modified has almost the exact same demotions as stock Baer bracket, I just moved the caliper mounting holes over .46 of an inch.


Here is a picture of the back of someone else's baer setup:
http://home.san.rr.com/iroc/Baer/f-inside2.JPG
http://home.san.rr.com/iroc/Baer/f-inside3.JPG



I hope this helps clear some of the confusing up

 

opps double post

 

The clearance we are lacking is not vertically it's horizontally. So a bigger rotor is not the solution to the problem (Like the 13 inch C5 setup). The C5 brake swap also has the same problem I am having, they sloved it with a spacer.

 

The only spacer that I'm using is on the outside of the rotor, so my wheel will clear the caliper. Someone using another wheel would probably not have to use the spacer.
Todd

 

If the bracket replaces the bump stop, then unless you make the bracket so the mounting bolt hits the stop on the a-arm, then removing the bump stop and using the brake caliper adapter bracket as the new stop allows the wheels to turn further than they were designed to. I guess you could weld a piece of 5/8" material to make the stop in the same place as before. This would solve that problem.

The only thing I'm concerned about is with the parts I have, my bracket thickness can be a maximum of 1/4" thick. That's a pretty big bracket with a lot of load on it for 1/4" material. I'm not comfortable with that thin of material acting as the caliper mounting bracket, and not to mention doubling as the bump stop. If you bent the bracket buy hitting the a-arm stops you would mis-align the caliper. Of course you can space the rotor out and make the bracket thicker, but I'm running stock 16" wheels with 255 x 50 tires when I race. If I spaced the rotor out more that would offset the wheel even more than the 5/16" that the thickness of the rotor already does.

I have an idea on how to solve the bracket problem. I've tried to take a pic and highlight the area I'm referring to. My idea is to use 3 bolts instead of 4 to mount the caliper. I'll attempt to explain this now.
If you look on the left side of the pic you can see where I've used a vise grip to hold the bolt in place for the pic. You can also see where I've cut the extension off the spindle as per the 1LE mod. If you look at the red area I've highlighted you can see the bolt boss on the cast caliper holding bracket. Unfortunately it extends past where I've cut my spindle. If I would have left enough material to extend out where the black highlight is, I'd of been ok.
So, if I hadn't cut my spindle off so close, I could drill through where the bolt is held by the vise grip. This way you only need 1 bolt on the bottom to hold the caliper since it would sandwich the 1/4" bracket between the spindle and caliper holder. On the top you definitely need to drill and tap the spindle, and use the bracket for the second caliper holder bolt. If this works, the bump stop isn't removed, and I honestly think that a 1/4" thick bracket would be of sufficient strength to do the job with this configuration.

Granted it will be a pain to drill the large hole on the spindle for the lower caliper holder bolt, but once the bracket is made, you could use the bracket to locate the hole. You would drill and tap the top spindle dust shield hole, then use the lower hole with the stock small bolt to attach the bracket to locate it, the just drill the hole bottom mounting hole using the bracket as a guide.

Anyway I hope I've explained this in a way that it makes some sense. If I had another spindle here I'd modify it the way I'm describing. But I can't get away during the week to pick up another spindle and the wrecking yard closes before I can get out of here, and this weekend is booked for me. But I'll try and con my son into going over and pulling another spindle for me so I can work on this after work.

So, give me some feedback on this idea. Am I crazy like my grand kids tell me, or am I onto something here.