C5 Brakes, Manual M/C, Pads?

[Mean 69]

I've had it with my hydroboost system. The thing works amazingly well on the street, I can't believe how well my car stops, but it is not what I want in terms of pedal feel for the track. I really love the thing, but I don't like the modulation, and am going back to a manual setup.

I want to hear specific, objective feedback regarding folks that use the C5 (not C4, that's what I have currently) in a manual configuration. What bore size M/C, and what types of pads are you using, what is the pedal effort? I am less concerned with performance on the track, in that there are tons of pad compounds out there that will work just fine, but lower temp street pads have eluded me so far for a manual setup.



The C5 calipers use a slightly larger piston size front, and "much" larger rear piston, which would better lend itself to a "larger" bore M/C. I have a manual 1", and a manual 15/16" that I can try, curious to hear others setups. When using the C4 in a manual config, I had dreadful stopping power, which it turns out may have been largely due to the Perf. Friction Z rated pads, they apparently have a very low coefficient.

Any and all comments/help would be appreciated. Oh, and by the way, in case why folks might be wondering why I would swap out a perfectly good C4 setup for a C5? Rotor thickness in the front is the main reason, the added heat capacity is going to be very important here very soon.

Mark

[Hydratech®]

Mark - have you tried some alternate master cylinder bore sizes? You might be very suprised how very differently the systems modulate when run on different master cylinders, as it really can be night and day.

If I recall, you are running that system on a somewhat smallish mc. I really think you should try a 1 1/8" bore mc on the hydraulic assist before yanking it out - you just might change your mind.

You will also find that the C5 brakes at the wheels will modulate quite better in and of themselves too

[MarkM66]

Mark,

Do you make your own caliper brackets? I'd assume the same bracket cant be use from the C4 stuff, to the C5.

I'd like to do a C5 conversion, making my own bracket, but not exaclty sure on the specs.

[Mean 69]

Good point, Paul. You are right (good memory!!), I run a mid year vette M/C, 1" bore. I might take you up on trying the larger unit out. In the end though, for this car, I will probably go with the manual setup. One reason, if I am successful at getting really low scrub numbers, is that I may do away with power steering altogether. It'd be a little tough to run the boost unit then!! I'll be building more cars in the near future, so I will undoubtedly use this on a later project.

Mark, yes, I typically make my own brackets, and "would" if the guys at Speedtech hadn't figured everything out for me. I am not too keen on their engineering prowess, based upon many e-discussion (or questions, with utter lack of credible answers), but the brackets are pretty straightforward. I may actually go with a completely different caliper, which is a radial mount, so that'll require a custom piece. I do know there are differences in the rotor standoff, etc, but I haven't looked too deeply into the rest of the stuff.

Mark

[MarkM66]

What do you mean by a "radial mounted" caliper?

[Mean 69]

It is just another way of mounting a caliper to a bracket, whereas most calipers have "ears" that bolts run through, the bolts running parallel to the kingpin, for instance, a radial mounted caliper uses bolts that bolt in perpendicular to the king pin to a special bracket. Poor explanation, but some of the high end Wilwood calipers, and the Alcon units that I am interested in use this type of mounting. The claim is that it is a more rigid mouting approach, so there is less give from the caliper under really hard braking.

Did you use to go by the handle MarkM68? I recall lots of communications with you years back on the Team Camaro site, you had a yellow 68 Camaro, right?

Mark (M)

[MarkM66]

Yeah, I use to go by MarkM68. I changed it to 66 because I have a '66 Chevelle.

I'm building a '70 Nova right now. I've found templates online to use C4 calipers and rotors, but I haven't found one to use the C5 stuff. I would imagaine it would be about the same. Just not sure if you can use a flat caliper bracket for the C5 stuff, as the rotor offset may be different.

[Salt Racer]

....the added heat capacity is going to be very important here very soon....

Interesting....


This might help you guys on fitment...


The offset is really shallow on C5 rotors, so spoke clearance may become an issue even with floater calipers.

I had to use C4 rotors on mine b/c of Wilwood calipers and street rod style wheels. They held up fine at Streets of Willow on my car (slow car on slow track). You Camaro's about 700 lbs lighter than mine, but with hp you have, C4 rotors are probably marginal especially on faster tracks.

When I redo my front suspension, I'll probably do 13x1.25 or even 1.375" rotors with custom offset hats.

EDIT: another thing to concern besides the rotor thickness, is the thickness of pads. PBRs, or any other OE type calipers for that matter, use pretty thin pads. My front calipers take 0.8" thick pads, so I'm pretty sure that helped. I have about 5000~6000 miles since I did the brake conversion with one track day. Polymatrix E pads ate about 0.015" off the rotors. I think the rotors are done after Buttonwillow. I just got a set of PFC 01 pads.

[Mean 69]

Katz, you stud!!!! Looks like it will be custom rotor/hat time for me after all! Great pic, thanks a million. I thought about the thicker-er rotors too, but at this point, I'd really just like to slap something on there quick so I can focus on the other new aspects of the car. Man, the C5 stuff is so cheap, it is just crazy. GMpartsdirect.com has the calipers for about $80, new, no core. $50 for the rotors. Can't beat that.

M

[Salt Racer]

You're welcome Mark.

Yup, C5 stuff is really cheap for some reason. Back when UCA/LCA and knuckles weren't restricted-availability parts, they were really cheap too. (like $130~150ish for each component).

I know you aren't a big fan of Wilwood, but they do have off-the-shelf hats for C4 application. It actually moves rotor face towards inboard by 1/16" or so. Part# is 170-6837. I think the combo of those hats and C5 calipers is probably the quickest way to do 1.25" thick rotors. You can probably re-use your existing brackets with minor mods.

Katz the stud

[Mean 69]

Dear stud (aka Katz),

You are correct, I am not a huge fan of the Wilwood stuff, well, at least not the ordinary stuff you can buy from Summit, etc. But, you are right again, I was thinking that the Wilwood hats could work well, if I found the right one. Looks like you found it for me, I'll have to take a look. One thing that I adore about Wilwood is the fact that they put engineering drawings on their website, it just does not get any better than that. Very convenient. Floater time!!!

So, if you want to make me even happier, would you, by chance, know the thickness of a rear Z06 rotor? I am guessing that it is the .810" that the C4 stuff is, but clearly this is not my area of expertise. Could you guide me, oh-wise-one?

M

[Salt Racer]

Well, I guess I'm officially the stud now LOL.

I totally agree with you. I don't like Wilwood's typical street kits either, which I'm speaking from my own experience. 0.810" rotors are simply not adequate for front of 3000+lb cars.

I too like the fact that Wilwood has very good engineering drawings in their catalog and web site. When I did the front brake on my Riv, caliper/spoke clearance was critical. I designed all brackets based on measurements I got on their website (and my own measurements on C4 rotors), and everything was spot on!

I think C5 Z06 has the same rotors as a standard C5? I know for a fact that calipers are the same, except for fancy red finish. C5 rear rotors, which I have on the back of my car, measured 1.035" thick when brand new. Offset is shallow just like the front. The height of hat is 0.875" from the outside friction face of the rotor. The thickness of the hat itself (wheel mount face to axle flange face) is 0.300".

I used them b/c they were cheap (I paid $35 each), and I figured I can pick up some backing plates w/ internal parking brake at junk yard and adapt them on my axle. Hat offset was just enough to give me caliper/spoke clearance with Wilwood forged Dynalite calipers and pathetic caliper clearance of my current wheels.


I got thinking about one more thing about front brake. How close is the PBR caliper cradle (pad holder, or however you wanna call it) to the base of rotor hat? OE C5 rotor's hat measures 8.45" diameter at the base, and Wilwood's hat has 12x8.75" rotor bolt circle, so the hat must be 9.25" or so in overall diameter. PBR calipers may not work. I should have checked. Sorry about that. Crap, nothing is easy nor cheap.

I shall resign my stud status...

[SHANE 73Z]

mean69,

The C5 & LS1 F-body are essentially the same. They use a 12"x1" (approx) rotor (with different offsets of course). They both use a small drum inside the rotor for the e-brake. The LS1 f-body conversion has been discussed here before.

Shane

[MarkM66]

mean69,

The C5 & LS1 F-body are essentially the same. They use a 12"x1" (approx) rotor (with different offsets of course). They both use a small drum inside the rotor for the e-brake. The LS1 f-body conversion has been discussed here before.

Shane

The C5 and LS1 don't use the same rotor. See image above. C5 uses a larger rotor.

Calipers are the same, abutment brackets are different.

I also think a normal C5 uses the same rotor as a Z06.

Mark, make sure when you price those calipers, that they're coming with the abutement bracket. If you need those.

[SHANE 73Z]

Mean & Mark,

I was referring to Mean's question about z06 rear rotors. The O.D. and thickness are essentially the same for all c5 & ls1 f-body rear discs. There are some subtle differences that make them not interchangeable (mainly the offset).

Shane

[dennis68]

No difference in hat spacing or thickness/overall rotor OD between the Z06 vs std C5. C5 rear rotors measure 1.050"ish (don't have a brand new in front of me) and OD is spot on at 12".

[MarkM66]

Mean & Mark,

I was referring to Mean's question about z06 rear rotors. The O.D. and thickness are essentially the same for all c5 & ls1 f-body rear discs. There are some subtle differences that make them not interchangeable (mainly the offset).

Shane

Sorry, I thought you were refering to the front rotors.

[dennis68]

PS, I am running C5 fronts/9.5" drums and a 15/16" manual M/C. Pedal is rock hard right at the top. I may actually go SMALLER to gain some more pressure at the calipers...it would be nice to not have to hit them so hard in a panic stop situation and I have plenty of pedal throw to give up. I am curious as to how pedal feel will change if at all with the addition of rear discs.

I am running Bendix ceramics on the street.

During normal driving they stop fairly well, I wouldn't give them up for the added weight/clutter/bulkiness/possible failure of a hydroboost or vacuum assist unit.

[fuzzyonion]

To be anywhere near the stock cylinder ratio for a 1stgen with manual front disc, you would want a <7/8 with the C5 calipers, and a <13/16 with the C4 PBR calipers. 2nd gen Camaro would need a <13/16 and <3/4 respectively.....
as long as you pick one designed to flow enough fluid to each circuit.

That's my completely objective feedback, as it was only arrived at by means of mathematics to determine the mechanical advantage (ratio) of the master cyl, not real-world use.

[indyjps]

check out www.musclemotorsports for custom hats and rotors, offer a wide range of nascar 1 race pulloffs.