alloy

iTrader: (16)

Well I'm sure I could borrrow the cones, but finding a place to do this without being arrested is a problem. I'm talking to a few friends about this, but time is short. My "new" plans are to try and get the front brakes on this weekend.

The only thing I'm worried about is if I have too much front braking with the 12" rotors and calipers with the stock rear drum brakes. I'm upgrading the front braking power substantially and I'm not sure how this will work with the rear drums. They may be too much. I have a 2 day autocross event coming up the 7th and 8th, and I really don't want to miss it because I don't have my new front brakes dialed in.

If I could have gotten this done last weekend I would have had 2 weeks to dial the combo in, but now I'll have less than 1 week. Soooooo, not sure what to do.

89 Iroc Z

I have an older G-tech pro, I think it measures 60-0 stopping distance. Which I can do on a road near where I leave (late at night of coarse) that has a 55 mph speed limit. I will check it out. I have to put my whole car back together before I can try it.

Alloy, you are going to need the 1LE master cylinder and proportioning valve combo for the C4 setup.

Justins86bird

I'm currently running front 12" 1LEs and rear Al drums using the stock drum prop valve and they seem to be balanced as good as with the 10.5" front discs. I think it would be much better with rear discs, thats why I'm doing a LS1 rear brake upgrade.

alloy

iTrader: (16)

Hey thanks for posting that Justin I really appreciate your taking the time to do that! I was kinda waffeling on whether to put the C4 brakes on this weekend because of the autocrosses coming up. I enjoy them so much I would hate to miss a double event like this. Especially if it isn't raining

I'm also thinking about making some solid tie rod sleeves of my own. I've got some 4340 material and a 5/8 x 18 RH tap, so all I need is a 5/8 x 18 LH tap and 4 jam nuts. I'll probably order the tap tomorrow and it should be in on Monday.

Thanks agian!

Justins86bird

Do you still need the measurements? I can take them off my LS1 backing plates.

alloy

iTrader: (16)

I'd love to have the measurements. Thanks agian!!!

Justins86bird

Here you go.

machinist

Hey guys.

This is Dan-Alloy.

I'm logged in as Machinist because I updated my email address and now the system won't let me post under my Alloy account. I've emailed the webmaster, but not sure when I'll get a reply.

Justin-Thanks for the measurements. I'll check mine out and let you know if they match mine. It might be next week before I have time to do this. I'm still going to try and get everything installed this weekend. I'm also putting in new ball joints, and if the tie rod ends are bad they will be replaced also.

I can't wait to try this out

After I get everythign installed, I've got an alignment appointment on Wednesday of next week, so hopefully everything will go smoothly.

machinist

Ok, here are some pics of the spindle modifactions I made to a left spindle I picked up today from the wrecking yard.

The first pic shows my bracket installed on the spindle with only the one dust sheild hole drilled and tapped. The top hole is the one I drilled and tapped, the bottom hole with the allen bolt in it is the stock dust sheild hole.

With the bracket bolted on you use it to mark the cut line on the bottom part of the spindle, and more importantly use the bottom 9/16" hole as a guide to drill the spindle for the lower caliper mounting bolt.

The second picture shows the cut line on the bottom of the spindle. The top of the spindle is modified exactly like the 1LE is. The third picture shows drilling the 9/16" hole using the bracket as a guide. This hole is just drilled through and not threaded.

As a side note I also took the time to grind the casting flash off the spindle after a piece of it jumped out and decided to dig into my soft flesh. After 10 minutes with a die grinder, no more casting flash, and no more blood seeping out of me.

I've just painted the spindle and am waiting for the paint to dry. I'll post more later as I go along.

ebmiller88

iTrader: (7)

I think this has already been addressed in the C5 thread, but I don't think it has in this one.

What's the deal with studs? I take it we will need to go about 1/4"-1/2" longer than stock to compensate? I feel a Summit order coming.....


Ed

89 Iroc Z

The studs were address in an early post by alloy here:

When I do get to that point I am going to use a stud with the same knurl diameter as the stock stud, so no drilling, just a little longer.

machinist

It's me agian-Alloy logged in as machinist. I'm still locked out as alloy from posting. Wish I knew why.

Anyway I wanted to point out I made a mistake on how much the rotor deducts from the wheel stud length. It's 5/16" it deducts not 3/16". This makes it even more critical to replace the studs with longer ones.

I looked for the same diameter knurl studs but dind't find any, so I went with the ones from Jeg's. Even with the "handling" fee from jegs they were $10 less than I could get them locally. and no one had a full set of 20 locally. They had to order them in, so I just went with Jeg's.

And, it's really no big deal to drill out the stud holes to 1/2" to use these studs. Only takes a couple of minutes and the studs press in really well this way.

If you find studs with the same knurl diameter as stock, can you post a part number for them? Maybe you can find them cheaper than I did.

Forgot to mention, I used ARP studs #100-7708. They are 12mm x 1.50 thread, 2 1/2" long. They are $11.99 for a set of 5 from Jeg's.

http://www.jegs.com/cgi-bin/ncommerc...32&prmenbr=361

ebmiller88

iTrader: (7)

Yep, Summit has those also for the same price but they're on backorder. That's what I'll use unless, as Luke mentioned, we find them in stock knurl size but longer.


Ed

machinist

Two months ago when I ordered my studs, Summit was out of them then, and still is now. It was the same thing with my Hurst billet plus shifter. Summit was back ordered, Jeg's had it in stock.

AlexJH

I was wondering, are the calipers from the Vettes the same as the PBR calipers from a Mustang Cobra?

355SS

iTrader: (1)

Has anyone ever thought of using the 1LE rotors with calipers from the 13" C4 brakes and a custom bracket. 1LE rotors are 12 x 1.040 and the vette calipers are for a 1.080" thick rotor. This would give you a 12" rotor and a caliper that is very easy to find and fit under 16" wheels. It would save you the cost of machining the rotors into hubs. I checked at Autozone and Advanced Auto's web sites and rotors are $70 and loaded calipers are $85. C5 and LS1 cars use a 1.250 thick rotor which is to big.

89 Iroc Z

Please read the full post, this was already addresses.

The 1LE rotor will not fit in a C4 Caliper. The C4 rotors are thinner then 1LE rotors and the C4 caliper have a smaller caliper opening.
Look here:
http://home.cfl.rr.com/shuhy/brakes.htm

The 1LE rotors are 1.1 inch thick and the C4 rotors are .81 inch thick.

355SS

iTrader: (1)

As I said C4 13" rotors are 1.1" they were an option on all LT1 cars and standard on ZR1's and GrandSports. The calipers that go with them will also fit the 1LE rotor

89 Iroc Z

Wow, didn’t know the 13 inch C4 rotors were thicker, thanks for the info.

By doing it, that method I think it would cost the same as the 1LE setup. I do not see any benefit using 13-inch C4 calipers and a 12-inch 1LE rotor instead of just doing the full 1LE setup. Maybe if you get a good deal on some used C4 13 inch calipers it will be worth it.

toddlsf

I don't think that the C4 calipers would work on the 1LE rotor. I thought about that when I was working on my C5 setup. The caliper carrier for the 1LE has a larger radius on the bottom of it toward the mounting point of the wheel. The Corvette caliper carriers don't have this large of a radius and I don't think it would clear the 1LE rotor. I didn't test fit, I just assumed it wouldn't work and went a different route.
Todd

89 Iroc Z

toddlsf good point, a 13 inch C4 caliper will not work with a 1LE rotor because the C4 caliper carrier is not curved to accommodate the 1LE rotor.

ebmiller88

iTrader: (7)

Well now I'm pretty damn stoked. I thought I was gonna have to take my rotors to a machine shop to get them turned into hubs but I managed to figure out the lathe here at work so I got them done and they're not too shabby if I do say so myself. Looks like this here upgrade is gonna run me less than $200 after all:

C4 complete brakes: $150 shipped
Machine work and brackets: FREE
New studs: $25


Yahoo!!

Alloy, I really have respect for machinists...How the hell do you center these things? The lathe I used has the 4 chucks that move independently of each other and I had one heck of a time getting the cone thing centered, that took a LOT of time.


Ed

Dave Y

I just did a brake job on a 1994 Vette- non-HD, and the rear rotors are the same thickness, but the hat is about 1/8 inch (approx, unable to measure at the time) shallower (mounting face of hub is closer to the rotor (actual braking surface), they did NOT have the drum style parking brake, they used a funky setup with a plate behind the pad (around the piston), pins, spring and some levers for the parking brake.....

the ONLY diff. was the depth of the hat

machinist

This is Alloy again posting as machinist. Hopefully someone will fix my alloy account soon.

Ed,

I'm glad to hear things are going so well for you. Ya done good!

So now you know how to use a 4 jaw independant lathe chuck huh? Well look at it this way, next time it will only take you 1/10th the time to dial it in But I must confess, I used my 3 haw self centering chuck most of the time. I only use my 4 jaw for off center turning or when I have to dial something in to a knat's a**.

Dave, thanks for the info on the rear rotor. Ed is getting some rear rotors with his stuff so hopefully this will work and eliminate the need to mill off the caliepr carrier bosses.

Ed, when you get your brake stuff, can you check the offset, the rotor diameter, and the width of the rotor friction surface for us?

I'm pretty well on my way to having my front brakes installed on my car. Got the left side spindle and brakes off, and the a-arm off and the new Del-A-Lum bushings along with a new ball joint installed on that side. The bushings are the hardest part of this job. But after seeing how much the stock rubber bushings are deflecting I'm glad I went ahead and installed the new bushings.

The only real problems I've had don't have anything to do with the brakes. I broke my spring compressor and had to go "rent" one from the "Zone". And now I've just got my left side lower a-arm off and the ball joint pressed out and discovered the new ball joint had bad threads on it. So, another trip to "Da Zone" for me to get a replacement.

One thing I did run across when I was hooking up the Earl's brake lines to the C4 caliper was that I discovered that the banjo bolt for the 3rd gen calipers has a different thread then the C4 calipers. I only got one banjo bolt with the C4 setup, so looked it up online and looks like they are a dealer item only. But luckily I have the rear setup with the PBR calipers so I stole a banjo bolt off one of them for now.

Here is a pic of my left side setup installed.

RMK

Could someone tell me how much the C4 rotors come in at through the likes of Autozone or somewhere simmilar? I'm in the UK at the moment hence unable to find out. I tried their web page but I got a message saying there was a server error with the page I wanted to look at.

Prices I have found in the UK are:

Caliper-bare, no carrier etc $120
Rotors $57

Thanks

Rob

machinist

The auto zone rotors are about $85 each.

Well it's finished now and just took it for a drive. Nothing rubs, nothing leaks, and nothing makes bad noises

As all of you know I used the "used" rotors I bought along with the used pads that came with my C4 setup. I think I should have got new pads. I guess the reason I say that is it isn't the huge eye open difference I thought it would be, but then again I could only get up to 30 mph and stomp the brakes near my shop. And, I did replace the lower a-arm bushings with the Del-A-Lums and the car feels "twitchy" now. I know it's because it's out of alignment, so I'm not going to drive it much until I get the front end aligned on Wednesday. I'll give it a more "spirited" test then.

I may just pick up some new rotors and pads and throw them on before the weekend.

Justin, what was your impression of the difference with the 1LE front brakes?

Justins86bird

I noticed a difference, but it was not a huge one. When cold, the 1LEs are much better. When warm, there is a slight improvement. Keep in mind that I used to run Performance Friction pads on my 10.5s and I'm now using Hawk HPS on my 1LEs. The PFs weren't very good at all when cold. I attribute a majority of the better cold braking to the better pads. I am also using new 1LE GM hoses, not braided. IMHO, unless your old 10.5 discs were in bad shape, I wouldn't expect you to see a "huge eye open difference" on the street.

89 Iroc Z

Alloy A.K.A. Machinist,
To get the full performance increase out of your C4 brakes you are going to have to use the 1LE proportioning valve and master cylinder. Otherwise you are not going to feel a big improvement.

machinist

Well maybe I was expecting too much from them, and it has been about two weeks since I've driven the car. It still had the race tires on it from the May 17-18 events, so my impression wasn't a drive it-change it and type of comparison. But I did notice how really rock hard the brake pedal is now. It was very firm with the old brakes and the Earl's lines, but it's twice again as hard now with the new setup installed. Not sure why, but just an observation on my part. The brake response seems quicker too. It's a good feeling to when you hit the brakes. Really lets you know something is there if you need it.

My 10.5 brakes were in excellent shape, with really good pads. I just picked up my tools and cleaned up the shop and was looking at the brakes I pulled off, and was very surprised at how good they look after all the abuse I give them.
On another note, I threw the old brakes, spindle, caliper etc. on my shipping scale, and came out with 43 pounds. As I recall the C4 setup was 44 or 45 pounds. I really thought after cutting the extra material off the spindle and going to the much lighter aluminum PBR caliper that the new C4 setup would be lighter, but it isn't. I guess the extra weight is in the rotor itself.

I really hope someone else gets their C4 brakes on and posts their impression of the difference over the 10.5 brakes. I'd like to hear a 2nd opinion on this.

Now I've got to get going on the rear disk conversion.

machinist

I read the the J50 Disk-drum master is the same one that the 1LE cars use. I've ordered the 1LE prop valve, but it's for disk/disk
cars as I understand.

So what is the difference between the J50 master and the 1LE master?

I must admit I'm kinda confused. Are you saying I'm supposed to use the 1LE prop valve with my disk/drum setup?

IndyTruck

Back when you could still buy new 1LE parts (and new 1LE Camaros!) I was a chevy parts guy. I used 1LE rotors on Caprice wagon spindles on my 79 GrandAm. The story at the time, and I see no reason to disagree, is the 1LE IS a Caprice wagon/cop rotor. edit: with a small bolt pattern, of course.

Forgive me if I have stated the obvious, or if I've missed something. But it seems this needed to be mentioned.

Excellent work on the brake swap, guys! I'll be following your lead soon!

kevin

89 Iroc Z

I got my LS1 front brakes in the mail today and all I can say is they are HUGE! I am definitely going to go with the LS1 brakes. I hope they fit under my 16-inch wheels, if not I will trim down the heat sinks. The LS1 brakes have more pad area and a thicker rotor then 1LE brakes.

The mounting holes one the LS1 calipers are about 1/16 inch farther apart then the C4 brakes and use smaller bolts. I will get the exact measurements of the LS1 breaks later this week. The caliper seems to be almost identical to the C5 caliper.

The Baer “Grand Touring [GT]” brakes use the same caliper (just have there Baer logo on it. Also the LS1 brakes are the same thickness rotor (1.25 inch) as the Baer GT brakes. As many of you know, Baer uses stock GM parts, slap a Baer logo on the caliper and charge an arm and a leg for them.

If anyone knows anyone who has the new Baer GT kit and can get some dimensions of the bracket let me know, otherwise I am going to have to mock my own bracket.

Here is a picture comparing the C4 caliper (left) to the LS1 caliper (right)

89 Iroc Z

Another picture comparing the C4 caliper (left) to the LS1 caliper (right)

89 Iroc Z

The LS1 brakes are cheaper and better then the 1LE brakes.


The LS1 rotor has a different offset then the C4 rotor but this should help move the caliper out more so that I can squeeze in a thicker mounting bracket.


Another picture comparing the C4 rotor (left) to the LS1 rotor (right)

89 Iroc Z

Maybe I should start a new theard for LS1 setup.

EDIT:
Started a new topic. Go here for all the LS1 Brake info: https://www.thirdgen.org/techbb2/sho...postid=1333673

lock

Whoa, didnt realize how nice the LS1 brakes were. I think a new thread would be nice. Would give us a C4, C5 and LS1 comparison.

Scott_92RS

Thread? Hell, might as well start up a new section in the forum called "Brake Swaps"

ebmiller88

iTrader: (7)

Again, NICE work Luke.


Ed

ebmiller88

iTrader: (7)

Got my brakes in today. Like I said, the guy threw in the rear rotors 'cause he didn't need them. The entire system has about 10K miles on it and everything, except for a bit of brake dust, looks brand new.

Both front and rear rotors are exactly 12" wide and 13/16" (.8125") thick. The ONLY difference is the height of the hats, as seen below. The front rotor is on the left, the rear on the right. The front rotor is 1/4" taller than the rears. Also, there is no "LS1" style internal drum brake in the rear rotors, I think that was covered already.

So, if they're the same, maybe you could run the rear rotor up front? I'll fit it up and see what happens. I'm only waiting on my new ARP studs to arrive from Jeg's.


Ed

ebmiller88

iTrader: (7)

Here they are side by side:

ebmiller88

iTrader: (7)

Front:

ebmiller88

iTrader: (7)

Rear:

toddlsf

One possible problem that I see is that the caliper will be closer to the wheel. That is the problem that I had. The inside of my wheel rubbed the face of my caliper. All I had to do was use the IROC spacers up front. Different wheels won't have this problem though.
Todd

machinist

Ed,

In your first pic it looks like a 1/2" difference in the height of the rotor. Or am I not seeing it correctly. The pic is kinda dark.

If it is 1/2", then it's probably too much of an offset to work correctly.

89 Iroc Z

The rear rotors do have a better offset to allow to a thicker caliper mounting bracket. But as toddlsf said, the caliper may rub the front of the rim.

I Photoshoped ebmiller88's picture so you can see it beter. Thanks for the info and pics Ed.

machinist

Thanks luke. Looks like about 1/8" now. That might just be the perfect offset and we won't have to mill off the caliper carriers.

With only the rotor being offset 1/8" more to the outside, I don't think there will be a problem with the caliper or caliper carrier rubbing the wheel. Before I milled off the .1 on my caliper carriers to center them on the rotor, I checked the fit in a 15" and 16" IROC wheel and there were no problems with clearence at all.

I guess Ed will let us know if he runs into any clearence problems.

Justins86bird

I would like to bring up a few points. With so much info in this thread, I'm not sure if they have been mentioned or not yet, but I don't remember that they have.

Compared to the stock 10.5 discs, the 1LE rotors have the wheel's mounting flange about .5" farther out, which helps the wheel clear the larger caliper. I would imagine that you would want a fairly large offset on the hubless disc to simulate this.

If you turn the stock 10.5" disc into a hub, and place the hubless rotor on, I would assume that the caliper will be closer to the wheel then it is with the stock 10.5 setup. With a larger caliper, you may have to run a spacer. With the rotor already spacing the wheel farther out, using a spacer would put additional force on the studs.

The 1LE outer wheel bearing is larger then the 10.5 and has a metal cage instead of plastic. Don't know if this is significant or not.

Also, the wheels are designed to be mounted hubcentric. There is only a very small area on the hub which is machined (right at the wheels mounting flange). Once you move out from this machined area, the wheel will no longer be positioned tightly to the hub.

BretD 88GTA

No difference. They are the same. In fact, my '88 J65 disc/disc GTA was supposed to have a different MC but it does not. I bought a new GM J50 MC and it is identical to the original MC on my car.

The 1LE prov. valve should help as I understand it.

ebmiller88

iTrader: (7)

Yep, I misspoke. It's only 1/8" difference. The rear rotor (right one) is 2" tall, the front rotor (left) is 2 1/8" tall. Thanks for fixing the pic Luke.

With respect to the 1LE M/C and prop valve issue, per the manual, you need to swap both on '88 and older model cars. '89 seems to be the transition year, and you should only have to swap the prop valve on '90 and up cars as the M/C is the same on all cars in these years. Some guys who did the 1LE swap left their stock parts alone and say they have no problems, but I switched mine with the correct parts and the brakes work great.


Ed

ebmiller88

iTrader: (7)

Justin touched a few points of interest in his response.

The 1LE rotor does push the wheel out more to clear the caliper so maybe it would be good practice to use the front rotor which gives a little more (1/8") offset. I will try both to see what happens anyway.

He mentioned that the 1LE bearing has a plastic cage. Is this the case with the GM 1LE bearing? I used Timken bearings with my 1LEs and they are all steel throughout. I would assume that the larger 1LE bearing is used to compensate for the larger, heavier rotor. I wouldn't think this would be an issue here since the rotor/hub is the stock size. I am curious to see what the weight difference is between the stock rotor, caliper, and spindle and the "new" Vette rotor, hub, bracket, modded spindle, and Vette caliper, etc.


Ed