I've tried searching and found nothing more than brief tidbits in different places. What I'd like is to start a TECHNICAL comparison of the different brackets out there that allow you to use the larger C5 rotor (and caliper)

As far as I know- UMI is the only sponsor who has brackets readily available.

But I know of other places that sell other brackets that are non-sponsors- So I guess we have to keep names and links out of it and stick with technical descriptions?

* There is of course the UMI piece which is made out of 2024? Aluminum
* There is one very simililar to the UMI piece made out of 6061? Which is said to be less affected by heating cycles?
* There is another of the same design made of steel

All three of these require cutting on the stock spindle- which I don't think is very cool

* The LG design does not require cutting (this alone would sell me on them, assuming the design is still strong) but I cant find it for sale anywhere, nor what material it is made out of.

{(what I'd really like to do is to find or borrow some of the LG brackets and find someone who will copy them and produce a batch of them in a good sturdy steel)}

If you know of any other sponsors who offer brackets please speak up

If you have any good info on why a particular rig is better than another, please share

Thanks

Dave

 

now this might be a newbie thing to say, but cant you just bolt the c5 caliper up to the fbody bracket as is? i know youd have to use stock rotors, but the caliper is slightly better from what i gather.

this is something id be interested in since im still on stock 16s so if they will fit then id start off with c5 calipers and braided lines, then upgrade with the brackets and larger rotors when i got larger wheels.

 

I have a set of the steel ones, Bob Bishop, but don't know
if I'm ever going to use them. I saw where "trackbird" had
picked up the design and was having them made in batches.

LG Motorsports has never listed them and you have to ask.

 

You can get them through LG motorsports. You just go into the brake section and click on the G2 GStop LS1 F-body Brake kit. There is an option that allows you to order only the brackets without the other hardware.

 

Here's the full list of Bishop-style hub mounted C5 adapters as far as I know. There's no prices or links, so I think this is all kosher.

-original Bob Bishop steel brackets, no longer available
-Bishop aluminum (anodized), marketed through various channels in the past,
now licensed and marketed as Trackbrackets, available through Speed Specialty and direct from trackbird, but made in limited batches
-UMI aluminum (powder coated), publicly admitted to be a copy of the Bishop design (which was no longer available at the time) with some modifications, appears to be based on the Bishop steel design
-BMR 4130 chrome moly (powder coated), obvious copy of the Bishop design
-Kore3 steel (plated), appears be an independent design, notably lacks the rib between the caliper mounting bosses

The LG brackets are completely different. They are designed to use the fbody pad abutment bracket and pads. I think you can also use the C5 caliper, but still have to stay with the fbody pads. I think I've read that it can be modified to support the C5 abutment bracket and pads, possibly with a little grinding somewhere.

Fbody pads are slightly smaller, available in fewer compounds (but still quite a few), and the radius matches the stock rotor.

Besides beings pressure cast, C5 calipers also use smaller pistons (40mm vs 44mm). That certainly contributes to their improved spread resistance. The smaller piston is matched to the larger rotor and pad. I would not try to use C5 calipers on stock rotors because it would screw up the brake bias.

Doug Rippie Motorsports sells stainless replacement pistons for C5 calipers, but I don't know of a source for Fbody stainless pistons. Stainless steel is a poor conductor of heat. DRM does not claim that stainless will keep the boots from melting in track use, but it will reduce heat transfer into the brake fluid. Stainless pistons may also live longer than aluminum after the boots are fried and abrasive brake dust gets in.

FWIW, I melted 3 out of 4 front piston dust boots on my fbody calipers by autocrossing. They weren't totally destroyed, but the rubber lip that fits into a matching groove in the piston melted off. The result is more like a loose, sliding shock absorber dust sleeve - it still helps keep the heavy dust off, but it isn't sealed anymore.

I suspect the Stainless Steel Brake Tripower design is similiar to the LG design, and they appear to use a C5 abutment bracket and rotor (and so presumably C5 pads) with their own caliper (38mm stainless x 3 = a lot of piston area). I'm only guessing about the mounting details on this one though.

Personally, I wouldn't use the Kore3 brackets for any car that might see competition or track use. They seem to be a good company and I have purchased other parts from them; I just don't like their bracket design. They sell PBR C5 calipers without the Vette logo for those who prefer "stealth" to bling or need an extra millimeter or two of wheel clearance. PBR machines off the raised logo before finishing (anodizing, I think) the caliper.

Bob Bishop and UMI (Ryan if I recall correctly) have debated the choice of alloys and finish (the concern being the heat required by powder coating and it's affect on aluminum). I'm not qualified to comment on that debate.

All of the Bishop-style brackets place a big demand on the hub bolts. The stock bolts are class 10.9 with a black oxide or phosphate finish, but they aren't holding the brakes. Ideally, something like a class 12.9 flange bolt with a corrosion-resistant finish should be used. Unfortunately, that doesn't seem to exist. The big paradox is that high-strength bolts are more sensitive to weakening from corrosion, but also more sensitive to the plating processes. Mil-spec high strength bolts with cadmium plating do exist, but I haven't found them in a metric thread and they are very expensive. If you do find a source, please let me know, but be prepared to give up ol' lefty.

Trackbrackets are shipped with ARP 8740 flange bolts that are rated similar to class 12.9, but with a black oxide finish. The instructions say to avoid touching the bolts with your salty hands (wear gloves) and to paint the exposed ends after installation.

If any of the other kits come with class 10.9 bolts, I'd be very nervous about using them with race tires. I'd also be concerned about using anything much harder than class 12.9.

I would never reuse the bolts. If you have to pull the hubs and brackets off for whatever reason, use new bolts.

Another option for competition/track use might be drilling the brackets, spindles, and hubs out to use M12 instead of M10. M12 class 10.9 flange bolts are readily available with a black phosphate finish. Phospate is not the same as black oxide, but it still isn't cadmium or zinc. The bigger, softer bolt will probably still corrode a little, but shouldn't be weakened as much by it.

Note that the Porsche-based kits also mount to the hub bolts. The Stoptech and Wilwood kits bolt to the stock 98+ mounts, but these all cost more to buy and service than a C5 kit.

I've seen pictures and reports of uneven pad wear with the LG brackets in track use.

Frankly, you should probably only assume 1/2~2/3 of the pad depth will be usable "in anger" with ANY sliding caliper, aluminum piston design. Even if they do wear evenly, the pad material is an insulator and the aluminum pistons are not

As always, you can get away with more on a show-only car than on a car that sees wheelstands at the strip (followed by landing) or fat sticky race tires up front. YMMV.

 

I'm getting ready to do this conversion. Anyone have an opinion as to wether, or not, the Trackbrackets (and the UMI) are worth $100 more than the BMR?

 

Sounds like you want the LG brackets. Just call up LG and order a set. Don't steal there design and try to copy it.

 

Not really interested in the LG. It's down to the Trackbrackets vs. BMR, unless someone has a better option.

 

Not a direct copy as you mention, we used Bob's earlier design of the steel version as a sample, made our changes and used a different material choice. I have never personally seen a Bob Bishop aluminum bracket. And as from what I can tell the Bob Bishop design was a copy of the Baer bracket, which was steel and has reported to flex.

We have sold a 120 sets since we have began making our brackets with no failures or issues. We just had a customer last week purchase a set because his steel set purchased from another company bent.

If anyone has any questions regarding our conversion brackets please feel free to contact me.

Thank you,
Ryan

 

I find it hard to believe that a bracket of the same dimensions made of steel would bend more easily than an equivelant backet made of aluminum.

And has trackbird done a bunch of track testing with his/Trackbrackets design?

 

Some of the cheaper brk. are made with 3/8'' matl., most others
are 1/2'' Dale

 

The Trackbracket is 0.6" thick at the hub, the rib between the caliper bosses is almost an inch thick (I didn't measure the height, but it's well over an inch), and there's a very generous fillet.

Bishop did both lab and track testing. Trackbird bought the proven design, and it's still made by the same machine shop to the same specs.

That said, nobody is claiming that a C5 conversion is the ultimate road course setup. The C5 rotors do apparently require a cooldown lap if you get them really hot, or they may crack (on a real road course with real race tires). Some people have trouble and some don't. Some people are just harder on cars than others, even when both are running the same lap times.

Regular C6 rotors (not Z51, Z06, drilled, or slotted) are also compatible with the C5 conversion. They have an expansion ring that may help them last longer in severe use, but it's too soon to say.

The C5 conversion is a good bang for the buck upgrade, and it's all some will ever need. Others that are really serious (with big race tires and a fully developed suspension) eventually move to Porsche or Stoptech brakes. Still others racing in restrictive classes like CMC get by just fine with stock brakes and racing pads (with frequent caliper replacement, perhaps ...).

 

LG does list them, but it's a little weird. They are described as including Z06 calips, pad, zinc-washed rotors, and stainless lines for $1095.

The first selection box has only one option, brackets only, -$800.
The next box allows you to select between HPS pads (no incremental charge) or several higher priced upgrades to track-only pads.
The next box allows you to select between no rotor or a DBA rotor for +$65.

If you order brackets only, I have no idea whether you'll actually get a set of HPS pads, since the choices conflict. None of the available options include calipers, but you can get them from Kore3 or of course GM.

In case anyone doesn't know, the only thing special about C5 Z06 calipers is the color red. The C5 Z06 pads are different and reported to be somewhere between the HPS and HP+. The Z06 pads should work with any of the Bishop-style brackets, but I don't think you can use them with the LG kit without some modification.

The regular C6 caliper does fit the C5 Pad Abutment Bracket, but I don't know if it will fit the FBody Pad Abutment Bracket. The mounting is the same, but the caliper is slightly beefier so it might require minor grinding with the LG kit. I doubt if it would be a problem though.

The C6 Z51 uses the same caliper as the base C6, but the Pad Abutment Bracket is different to move the caliper out to fit the Z51 rotor. As far as I know the Z51 bracket and rotor should fit any of the Bishop-style brackets if you have 18" wheels. That might be an interesting option for anyone who trying to "fill" 18" street wheels. However, I don't know of anyone who has tried the Z51 option with race tires and pads. It's possible the extra extension would lead to flexing.

The base C6 rotor and caliper combo has been track-tested on a Bishop-style bracket, but one trip to the track by one person isn't really enough to declare victory yet.

 

Yes exactly, they are not the same dimensions. I have seen the steel brackets made from .188" and .250" thick steel. Like Sean mentioned the TrackBrackets are .600" and that is the same as ours.

 

The brackets we offer are 1/4" 4130 moly. If you have any questions regarding them feel free to ask...

Lee Spicher
lee@bmrfabrication.com
(813)986-9302

 

The trackbrackets have been quite thoroughly lab and track tested (someone asked).

And I'll correct Sean to say that they are now available in stock. No more dealing with GP's, they are available off the shelf.

I hope I'm allowed to add that (which is why I'm keeping it short).

 

as long as you arent road racing I wouldn't think it would matter.

 

While drinking my coffee this morning, I randomly clicked on a link that I thought had nothing to do with C5 brakes. Actually, I wasn't thinking about brakes at all, or anything really. Some of my comments regarding supplied hub bolts are apparently out of date.

Nevertheless, I'll stick by the spirit of my comments. The bolts that hold the hubs and brake brackets on are critical. Always use new bolts if to reassemble the hubs and brackets to the spindle. Actually, I would always use new bolts after replacing the hub even without C5 brackets. Don't buy critical bolts from Home Depot or Lowes; look for quality American-made bolts from a reputable source.

 

Just call LG to order the brackets. I called and ordered them over the phone, no hassles. Price was around $250 a year ago.

I have C6 calipers on the F-body PABs with LG brackets and C5 Napa rotors. The calipers fit fine, no grinding required.

 

i dont havent heard anyone doing this but im going to try the c6 calipers with the z51 brackts and rotors.. does anyone see me having problems . i currently have 18in oz rims..