Well for now I think I'll stick with the master cylinder and prop valve I have. When I get the rear disks put on I'll swap the 1LE prop valve I ordered from GMPD. From what I can tell there is no different in the master at all.

Ed,

I weighed the C4 stuff and as I recall it was 44-45 pounds complete. The stock stuff was 43 pounds. So not much difference in weight. I'm interested to know what weights you get with your setup. From looking as the LS1 part pics, I can see they would weigh substantially more than the C4 setup. Hopefully we can get Luke to weigh his setup and let us the weight. Luke, old buddy, can you weigh the LS1 setup for us?

For now I'm going to stay with the C4 setup for several reasons. The first and most important reason is they are on my car and working. Secondly with the LS1 stuff I'm sure I couldn't run my 15" street wheels and tires, and even 16" are iffy. We should know more when Luke gets his mounted up.

The 1/8" additional offset of the rear rotor shouldn't interfere with the wheel at all. The offset of the rotor has nothing to do with the caliper positioning. The bracket is what positions the caliper. With the rotor 1/8" more offset, it should center in the caliper carreir perfectly.

I milled off .1 of my caliper carriers to center them on the rotor, and that's within .025 of 1/8". Before I milled off the carrier the caliper and everything cleared both my 15" and 16" wheels perfectly. So hopefully using the rear rotor will completely eliminate the need to mill the bosses on the caliper carreir, which will save even more money on this swap.

I am going to post more specs this week about the LS1 brakes. I don’t have a scale but I may take the setup to my local UPS mailing center to get it weighed.

Well the caliper positions is not the problem with the 2 rotors. It’s the offset from front to back. The offset of the rotor matters with caliper clearance. If a rotor has a very small offset the caliper will be closer to the front of the wheel and may rub. If a rotor has a large offset it will move the front of the wheel out farther away from the caliper and give more clearance for the caliper.

There are so many different offsets so people may be getting confused what I am referring to. When talking about caliper clearance, you have to measure the offset of the front of the rotor to the mounting area of the rotor. If you look at Ed’s picture you will see the rear C4 rotors will make the caliper much closer to the wheel and could rub.

From Ed’s picture it looks like the rear C4 rotor gives 1 1/4 inch of clearance from the front of the wheel and the front C4 rotor gives almost 1 1/2 inch of clearance.

Please re-read. In my post I said "The 1LE outer wheel bearing is larger then the 10.5 and has a metal cage instead of plastic". I used Timken too.

I guess I didn't explian myself very well about the rotor offset.

When you bolt the caliper on with the bracket, it's position is set with regard to depth. Whether the rotor is a front, or rear with the additional 1/8" offset, this in itself will not change the caliper location. If you have to space the caliper out to match the rotor, then yes it will make a difference in wheel clearence.

But from the looks of it, 1/8" more offset to the outside with the rear rotor is almost exctly what is needed.

I guess Ed will let us know when he starts putting it together.

So Ed, whatch ya doin this weekend???? Hint-Hint

Alloy, I guess I just interrupted your post wrong; we are talking about the same thing.

Justins86bird, My stock 10.5 rotors has all metal bearings. I did buy the car with 135,000 miles on it though so the previous owner probably changed the bearings. That’s pretty cheap that GM uses plastic bearing retainer.

Luke,

I'm glad we are talking about the same thing and got that cleared up. Don't want to confuse anyone more than we already have with all this tech stuff.

I bought my car new and it has the plastic bearing cage on the outside bearings direct from the factory. Honestly, I don't see a problem with using them. These went 145k on my car and look to be in perect condition, so I just cleaned them out, re-packed them and and running them as is.

He he...yeah right. I just got my Iroc back together from the SLP and Spohn install and took the wife's covered parking spot for 2 weeks so I won't be doing any wrenching this weekend.

However, I do go back to work tomorrow and I will be putting my hubs together. I just got my studs in today and my hubs are at work so I can press the studs in there tomorrow and I'll post pics of those too. They'll be pretty. Before the new brakes go on I have to pull the A-arms off and install new poly bushings, ball joints, and install new KYBs while I have them off. I'll have it all covered when that's done.


I have yet to make my brackets though. I will be test fitting the pieces to see if I can fit that 1/2" thick one in there with the rotors. Otherwise it's looking like a 3/8" thick bracket. I'll keep you posted.

Ed

Ed,

Well I was hoping you'd get to put it all togehter this weekend I'm very curious to see how the rear rotors fit up for you.

As far as brackets go, I don't think there is any way you can squeeze a 1/2" in bracket in there without some serious mods to the spindle and caliper carreirs. If you use the rear rotors and a 1/4" thick bracket, I would guess that the caliper carrier would be almost perfectly centered over the rotor. To go with a 5/16" thick bracket you would probably need to machine the caliper carreir bosses off .062 (1/16"). To go 3/8" thick you would have to machine off .125 (1/8").

Judging from my caliper carriers, I wouldn't recomend taking off more than .125 from the mounting bosses.


Anyway keep use posted on your progress. And I'll let everyone know how my brakes perform this weeked during my autocross events.

Ed,
according to my measurements there is no way to squeeze a 1/2 bracket in like alloy said. Unless you are going to use the C4 rear rotors. Is that what you mean? I would go with the proven safe Baer thickness of 5/16 and mill a little off the caliper carriers. The amount to mill off will matter on your hub offset.

I am going to measure the distance from the front surface where the rotor mounts on the Baer hub to the rear of the spindle mounting bracket. This will give a more accurate way of comparing the offset between the Baer hub and the milled down stock rotor hub. Then all you have to do is subtract the distance of the Baer hub (rotor mounting surface to back of spindle mounting bracket), which I will post, from the distance of the stock milled down rotor hub and that will give you the amount that needs to be milled off the caliper bosses.

I was just at A-Zone taking the spring compressor back I "rented" this last weekend to put the brakes and stuff on, and asked about the Aimco Extreme rotors. They counter guy called the factory for me and confirmed they are both drilled and slotted

As I recall they are $89.99 each, and take 4 days to get on a special order basis.

Difference between LS1 and C5 calipers.

Talked to a GM tech man and he said that the LS1 has dual 44 mm big pistons, while the C5 caliper has dual 40 mm pistons. Guess it has something to do with how much force oyu have to apply to the pedal and line pressure needed to move the pistons. He was a little unsure about this, he checked it out like 2 years ago.
I haven't seen any info about this, thought I'd let you know.

/Anders

Oops...I just threw that 1/2" figure out there. I knew it has to be somewhere between 1/4" and 3/8". I'll have to figure it out, too.


Got the hubs done. Now I have to get new bearings and put them on the spindles and get it all test fitted.


Ed

Ed,

I thought you already had 1LE front brakes. Your yahoo album has pics of them.

FYI

Just tried my space saver spare on the front of my car. The caliper rubs the wheel, but not very much. A 1/8" wheel spacer would take care of it easily. When I rotate the space saver spare with it bolted on, the paint is barely scratched from the caliper rubbing.

Yea you have the buy a 1LE aluminum spare. GM put in a lighter and bigger aluminum spare in the 1LE cars that will clear 12 inch brakes. It was also an option on non-1LE cars.

Here we go with another topic to talk about:

The 1LE spare is not the spoked aluminum spare most people think it is, that's the N64 spare which I happen to have. The true 1LE spare is a solid aluminum wheel painited black and I have yet to see a real one up close. Anyone got one?


I do, on my '88 Iroc. The C4 upgrade is for my '91 RS which will be receiving the PBR equipped 2.77 rearend presently in my Iroc when I get the 3.42 built.


Projects, projects...

Ed


UPDATE:

I just made a template for my brackets from Luke's bracket design. I copied his design that he posted in this thread into a MS Word document, blew it up to 158% original size to get the measurements right, and printed it out. Then I traced it out on a 1/4" thick piece of plexiglass and will fit it up accordingly. I will see how the front and rear rotors mount up and get the measurements we're looking for and then determine my bracket thickness.


Pics to come!!

I've got a quick update myself for everyone.

I just tried a 15" stock 5 spoke factory mag off of Dewey's 91 RS on the front of my car with the C4 brakes and it clears perfectly.

So don't be afraid of this swap if you have 15" wheels

I have heard that the 15 inch 91-92 wheels work with the 1LE swap but not the 15-inch 82-90 wheels. Do you have any you could try?

Geez, another thing to check! I didn't realize there were two different types of 15" 5 spoke wheels.

I don't have any older wheels, but I'll try and see if anyone around here has any to try.

Thanks for the heads up on this.

I have a set of '89 15" wheels off the car. I am in Ohio.

Let me know if you live near Akron, Oh and want to give them a test fit.

I figured it was worth a try.

Gus

Thanks for the offer, but I'm in Washington state

Well I had a chance to wring out the new C4 front brakes and Del-A-Lum bushings today at an autocross event. The new brakes definately work MUCH better than the stockers do.

We run 2 cars on the course at the same time at our events to make the events go faster, and on one of my runs the car in front of me spun and scattered cones everywhere, so they red flagged me. I had to stand on the brakes and EASILY locked up the fronts with the sticky tires on at about 45-50 mph. I let off them a little after they locked so I wouldn't flat spot my tires, but this just proved to me that I now can lock the front tires at will now if I want to. Before I could not lock the fronts with the 10.5 brakes even with street tires in the dry at these speeds.

The mounting brackets look perfect and everything is really tight after 10 hard runs. (we have 2 drivers in my car). Got another event tomorrow and if I run across any problems I'll let everyone know.

Next it's either the 4th gen rear disk upgrade or the hooker 2055's and Alston SFC install. Haven't decided which to do yet. I'm not looking forward to pulling the stock manifolds with the AC in my car.

How do you like the Del-A-lum bushings?

The front end seems tighter and more responsive with the bushings installed. There is more road feel transmitted into the steering wheel than there was before, and I've noticed my center rear view mirror vibrates all the time now. But it's not something that really bothers me.

I will say that the bushings were a royal pain to press into the a-arms. I've got presses, milling vises, and all the fixturing I needed to do the job correctly, but trying to get the aluminum shells to go in straight was difficult at best. From what I can see they made the aluminum shells way oversize, so pressing was not a fun deal.
A lot of material was pushed off the aluminum shells while pressing them in even though I used lube on them to help them slide into place easier. There was this sickening sound of the aluminum material being cut by the steel a-arm whle pressing them. But with that said, I like the results of the solid bushings over the stock rubber ones.

Since I bought the Del-A-Lum kit from Global West, I've found out that Herb Adams offers a kit like this with steel shells and a little different bushing configuration. If I had to do it again, I'd check out the Herb Adams kit first.

Wow, they were that hard to install eh. Well, maybe I'll just leave my poly ones in for now.

So how did you like the balance with the 12" discs and rear drums?

The front to rear balance actually seems better than before. I could lock the fronts before the rears if I wanted to, but by using the brakes sensibly (not locking them and flat spotting my tires) it was very balanced.

I guess it just goes to show you how inadequate the 10.5 front brakes really are on these cars.

Glad to hear it all works together. All I have to do yet is figure the bracket thickness with either the front or rear rotors. Ironically, persently I have no problem locking up the fronts in my RS. I replaced the calipers and hoses about 6 months ago, they work fine.


I just installed 1 3/4" SLPs along with my Spohn SFCs and it really wasn't that hard, but let me give you some ED-vice for the header install:

Passenger side:
1. Unbolt the A/C compressor from the serpentine bracket (if equipped) and "slide" it off to either side, you don't have to remove it. I actually just slid mine on top of the air intake hose.
2. Remove the dipstick tube and starter. This makes the passenger side go much easier and allows you better access to the plugs during reinstall. I could NOT reach # 6 and 8 from the top...impossible.


Driver's side:
1. Unbolt and loosen and/or remove the steering shaft. This gives you a whale of mobility that you do not have when it's in there.
2. Unbolt the master cylinder and also the prop valve from the vacuum booster with just the (2) 15mm nuts holding them on there. This will allow you to move the hard brake lines around and not scratch up your new Jet Hot coating, if equipped....

HTH...Ed

PS: See these header install threads for more info:

https://www.thirdgen.org/techbb2/sho...hreadid=176267

https://www.thirdgen.org/techbb2/sho...&highlight=SLP

Ed,

Thanks for the "ed-vise". I've read many header threads and that's why I went with the Hooker 2055's from Jet Hot that were already coated. Just not looking forward to getting my big hands and arms in there and tearing them up as usual in the tight space changing the headers.

Anyway, the front brakes performed well all weekend. Ironically several cars had brake failures during the two events. The failures were from a sheared caliper mounting bolt, broken spindle (caliper mount broke off), and a caliper just split in two on one guy. We had 24 hard runs on the car this weekend, so I feel pretty good about the strength of my mounting plate design and the spindle mods I've worked out. I definately could go deeper into a corner and brake harder, which made my times go down.

Anyway, just my 2 cents worth.

thumbs up to all that participated in the C4/C5/LS1 threads , but this is a lot of info to read and make sense of for a novice like me seeking better brakes.

I think it would be awesome if you guys could write up some tech articles and submit them , they would make it a lot easier for all of us (not saying you haven't done enough , lol , but a final tech article or even a final post in each thread would help eliminate all the if's but's and maybe's).

in any case , thanks for all the info , now I need to decide just what swap to do , lol

Anyone having trouble getting the rotor to sit flat against the hub face? Both my rotors won't go all the way down and sit on the hubs...the center of the hub seems too big for the center of the rotors. I'll sand the rotors up a bit but I don't plan on taking very much meat off of them. I just thought it was kinda wierd. I machined my hubs to 5.9 inches and they don't hit the inside of the rotor hats at all...FYI.


Ed

Mine were a snug fit, but they slid into place after making sure the new hub center was completely clean.

I guess there could be a difference in rotors and hubs due to manufacturing tolerances, but I guess I got lucky with mine.

Looks like I'm the only one staying with the C4 upgrade, huh? All you other suckers have jumped ship for the LS1s.... :nono:

Anyhoo, I was test fitting the stuff together last night and came up with a few issues. Sorry but I don't have any pics yet:

1. I am using a 1/4" plexiglass template just to fit things up and determine the final bracket thickness...it JUST fits in there and appears to work fine. Luke, I don't know how you got a 5/16" thick bracket to work, it looks like it's too thick to fit in my case. Maybe there's a difference in there somewhere. I am using my original but modified '88 Iroc front spindles that I removed when I did the 1LE upgrade. I will make another 1/4" bracket from steel today or tomorrow and see if there's any difference, but it looks like the 1/4" thick will work the easiest for me. (This is with the front rotor).

2. I also tried the rear rotor. What's cool about using the rear rotor is that you could probably fit a 1/2" bracket in there since the disc part of the rotor is moved more to the outside, away from the spindle. I will make a 3/8" thick bracket to try this idea and use washers to get the final thickness.

One problem with this method though. (Follow me here..) Using the shorter height rear rotor, the outer edge of the caliper carrier (the side nearest the wheel upon install) sticks out further than the rotor face meaning the wheel would hit it before the wheel face seats on the rotor/hub. However, this problem is avoided if you put a 1/8" or so rear wheel spacer between the wheel and rotor like the ones that are found between the rear wheel and drum on many cars like my '91 RS. This would work fine and only push the wheel out by a minimal distance.


I am sticking with this setup since I already have all the parts although the LS1 stuff is soooo cool. I'm just down to these final adjustments.



Ed

Well no, you are not the only one. Remember, I've had them on my car now for over a month I believe And as a side note, they work fantastically!

Anyway, I agree that the LS1 style rotors are nicer, but the calipers look ugly and don't clear 15" wheels which a number of people have to use because of snow tires for the winter, etc. I'm working on something to be able to use the LS1 style rotor, and still be able to use 15" wheels. Or use 16" wheels with the C5 12.75 rotors. Hopefully this will make even the C5 upgrade obsolete.

Anyway I'm still not comfortable with the 1/4" bracket thickness. Baer uses 5/16", and as far as I'm concerned you shouldn't go any thinner than 5/16", and I'd prefer 3/8" since the bottom bolt is now doubling as the steering bump stop.

To go with a 5/16" or 3/8" bracket you will need to mill off the mounting bosses on the C4 caliper carriers. And even to use my bracket style with 1/4" thickness, I had to mill the bosses off to center the caliper carrier over the rotor. This is something you need to check carefully. There is only so much travel in the bracket for side to side movement of the caliper, and you need to center the caliper as best you can for pad wear and to keep the caliper in it's holder. You also need to do this and to make sure you wear your rotors evenly on each side.

I have a set of rear rotors of a 4th gen camaro and as I recall they are smaller diameter, and have a narrower friction surface. I'll try and check on this over the weekend and verify what I'm saying here.

Yep, I forgot you already had them on..I forget things. I hear ya on the thickness issue. I clicked on the link that Luke posted a while back and the guys using these brakes on first gens are using 1/4" brackets:

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

Also, I have called every fab shop in my area and all they have is 1/4" , 3/8", or 1/2" thicknesses. I managed to get some 1/4" thick stuff here at work to make a template today just for fit up. But I realized that the only force this bracket should see is rotational force and nothing more. Theoreticallly it SHOULD be fine, but I'll keep looking for 5/16" thick metal for final fitment.



I have another spacing idea here:

I mentioned using a rear wheel spacer in the above post to move the wheel outward if using the rear rotors. How's this idea? I'm not sure of the dimentional changes yet, but what if you put the spacer between the hub and the rotor? This would give more clearance to fit in a thicker bracket.

I dunno...


Ed

Yeah, as I get older I forget things too. Who the heck are you again? Do I know you from somewhere I hate it when this happens


Anyway, yes spacing the rotor out from the hub will allow you to use a thicker bracket. But, keep in mind that this spacer needs to be perfectly flat, and when the rotor is bolted onto the hub with the spacer behind it the rotor must turn without any runout, or you will have a kind of surging like a warped rotor when you apply your brakes. I believe that's why baer made up their own hub with more offset instead of using a spacer. And not to mention they can charge an arm and a leg for it also

The 1/4" material is only taking rotational force, but don't forget it's also now a bump stop for the steering.

The 5/16" material is readily available if you buy a 20' length of it. I've got 3-5 suppliers locally that have it in stock. I'm sure if you offer to pay for the 20' length, the local fab shops will be happy to sell you 16" of it to make your brackets out of

I did not use a 5/16 bracket I used a 1/4 inch one. I said that’s what the bear bracket thickness is. However, the Baer hub has more offset to allow for a thicker bracket.

Also spacing out the rotor has already been discussed also… yea it’s a long post and I’m sure not many people remember everything that has been discussed.

Let us know what you do, if I was going with c4 brakes I would just mill down the caliper carries the correct amount to use a 5/16 bracket.

I'm probably just gonna have to read the whole damn thread over and take notes....


Ed

Hmmm, all the brake upgrade threads are now stickies. Wonder why?

Timken has produced outer bearings with plastic cages, but the Timken ones I've most recently picked up have been metal.

The 1LE outer wheel bearing is a 79-96 Caprice outer wheel bearing, which is also a 79-92 f-body outer wheel bearing which is also a 79-88 a/g-body outer wheel bearing.

Like the myth of the "narrow" caliper (70-76 f-body D52 variety) working w/ a 1LE rotor (they don't work w/ the 1LE rotor, but Global Wests pages say they do,) I wonder where the outer 1LE wheel bearing story comes from.

I dont know which other cars use the bearings, but a 1LE bearing (Set 3) is definitely different then the standard 82-92 f-body bearing (Set 34). Both std and 1LE inner bearings are the same (set 6). But the 1LE outer IS bigger.

I got around to playing with the setup a little yesterday. I was able to use a 1/2" thick bracket with the REAR rotor and it looks like it fit up perfectly with no cutting on the caliper carrier. (I used the 3/8" bracket I made with 2 washers on each bolt but the overall thickness is 1/2"). I had to use the spacer that I mentioned to clear the outer edge of the carrier but it looks like it will work fine. I am still trying to get the front rotor fitted up but that will probably take a little cutting of something to do so I will play around with it some more before I mess up any metal. I'm working on getting another set of brakes to play with.

SO, looks like if you feel you need to step up to that 1/2" thick(overkill) bracket, it just may work. I'll try to get pics tonight.


Ed

Speaking of caprice's, I just happen to have a 90 caprice that we sent to the scrap heap today, but before letting it go I pulled the front rotors and calipers off it, and master cylinder, along with the posi out of the rear end.

The front rotors are 11.875" in diameter, and measure 1.025 thick. They may be worn down on the thickness some, but's that's what they measure now.

I also decided to try them on a 3rd gen spindle, and guess what? They fit perfectly onto the spindle. I haven't checked the offset of the rotor yet or anything like that yet, but they do fit.

One problem I see with these rotors, and it's a major problem, is this car had the big 5 on 5" wheel pattern. I'm not sure if the rotors can be re-drilled or not.

But since the subject of caprice's came up, I just wanted to throw out this tidbit of information in case someone might somehow find it usefull.

There are ribs in the back which need ground way before you can redrill it. Doesn't sound like something that you couldn't do. Matter of fact, I have a pair of 84 Caprice rotors I'd love to have redrilled but I dunno if I can find anyone local to do it, or whether it'd be worth shipping them to be done...

Well those look like strengthening ribs to me. I'm not real comfortable removing them.

Shipping to re-drill the rotors wouldn't be cheap. Best way is to go directly to a UPS outlet and ship from there. Do not go to the post office and ship them. Bill Gates couldn't afford that shipping bill The post office is outrageous on shipping heavier items.

I know I ship stuff via FedEx Ground all the time. UPS has hosed people over way too many times; I refuse to ship via them.

I gotta take a flywheel in tomorrow so I'll take a rotor in and see what they say about redrilling a B rotor to 4.75" pattern. I'm not that worried about the ribs but I hear ya. For what I'd have in new 1LE rotors, they're worth bothering with, unless the bill to do it would be crazy.

I am pretty sure that 1LE rotors are just redrilled caprice rotors if memory serves me correct

Try Airborne for cheap quick service. We use them at work and they are a lot less than ups

Hey guys. I got to play with the setup a little more today and I think I have it down to this:

-3/8" thick bracket, which allows for NO cutting or further modding to the caliper carriers or spindles at all other than what has already been done. The rotor is centered in the carrier!
-REAR C4 rotor...wierd huh??
-ARP studs (ARP 7708)...gotta have them
-Iroc or drum rear wheel spacers; needed to avoid rubbing the caliper carrier as-is; HOWEVER, if you don't mind grinding a RCH off the edge of the carrier, these are not needed. They might not be needed at all but I haven't tried to mount the wheel yet.


I don't have it on the car yet but it looks like it's gonna work fine. Pics to come soon!!!


Ed

What's the difference between the ARP 100-7708 and the GM
22551491? I guess as mentioned, the ARP has a larger knurl. How about length differences?

-Matthew

From the ARP detail page at www.summitracing.com:

"Tough enough for competition.

GM: Camaro/Firebird/Corvette, late GM, 12mm x 1.5 thread, 2 1/2 in. long, .509 in. knurl diameter, wheel studs

These extra-long ARP wheel studs are designed for today's thick-centered high performance and racing wheels. The chromemoly steel studs are heat-treated and have a 190,000 psi tensile strength rating."

Sold as a set of 5.....$11 or so. You'll need them to account for the rotor hat thickness. I don't know what the GM P/N you posted is for.

Here's the pics I took. First shot is the top view:

Next is the rear view showing the bracket and modded spindle: