Problem with Carbotech shoes install

[hars550]

I am installing a new set of Carbotechs on my vintage vee. I also have a new set of German Drums.
When I install the drums I can barely spin them once I install the bearing nuts. Should
I get the drums tuned down and if so how much? It seems like the new shoes are thicker
than stock.

[Greg Davis]

Check to make sure you have the correct style adjuster. I believe the Carbotechs require the beveled style because of the shoe configuration.

[cendiv37]

Greg's probably right on the adjusters being the problem. Many suppliers only stock the so called "long" shoes which are to be used with the later, beveled/slanted adjusters. You can order the "short" shoes if you really want/need them, but they will take a bit longer to get. The Carbotech box should be marked short or long. If not, on the short shoes, the two working surfaces (against the adjuster and against the wheel cylinder) are parallel to each other. On the long shoes the adjuster end is at an angle to the (square) wheel cylinder end.

If you can find some of the later, beveled adjuster screws, installing them should solve the problem and allow you to use the long shoes. Either way you do need to match the shoes to the adjusters or they won't work properly even if you can get the drum on.

Lastly, Carbotech also makes pre-arced shoes, again special order. I don't think these are actually larger (probably smaller), but they do better fit the curvature of the drum. This makes them seat in faster. Stock drums are 9.060" ID and the standard Carbotechs are designed to fit this ID. If I remember, you can order shoes arced for 9.100" and maybe 9.080" ID drums, maybe even larger (going from memory). Special arc size, like 9.100" will also usually be written on the box. No size indicated would mean they are 9.060 "standard" arc shoe.

[brian]

If you cannot find adjusters you can grind the shoes to match the adjusters you have. By placing the shoes, toe and heel, on a flat surface you'll readily see what type of shoe you have. If they are tapered or "long" shoes one end will not lay flat on the surface. You can grind the tapered end to fit flush and use with flat adjusters. The later model tapered adjusters were a factory upgrade to help center the shoes and improve contact area and are considered the preferred application. Adjusters can be purchased by SR or LRE.

[hars550]

I do have the angled adjusters.I ordered all new star adjusters and angled screws. I got the shoes from
Sr Racing and they may have sent me the thicker shoe. My old drums fit fine. I just wanted to use
the new drums with the CT shoes. I think I will just sand the older drums since they had stock shoes
on them last season and they are in good condition.

[brian]

Call around and see if any brake shops still have a shoe arching machine. They can fit the shoes to either drum. A common problem with VW drums is heat warping. The thinner the drum, the quicker they warp.

[hars550]

I installed the old drums yesterday and everything is fine. They must have been the thicker shoes.

[brian]

Just to follow up on drum thickness. Minimum dia for a drum is 9.114. While you may be able to run a drum thinnner than min., it will heat warp very easily and will have to be turned again. Under the braking we do, a warped drum will cause you fits! If you don't have a method for measurement, observe the inside lip of the drum: does it have a slight bevel leading inward? IF it does, it may still have some meat left. If the bevel is gone, it's probably a throw away.

[hars550]

Well I found the problem.It was not thicker shoes. As I was installing my old drums I checked to make
sure the shoes were installed ok. I noticed that one of the new angled adjuster screws was
thicker on the high side than the other by around 1/16" to 3/32". I pulled the other screws
off and they were close to the same size. I installed the new drums and they fit but were
still to thick to get the drums loose enough as per Carbotechs bed in instructions.
I put on the old drums and no problems. It was just luck that I noticed the screw.
Problem solved. I will most likely install the new drums after the next race once the shoes
are worn a litlle.

[Ed Womer]

Since you appear new to the Carbotech shoes, you might want to know that you don't have to waste track time to bed the shoes and can do it driving around in the pits. Just drive around in first or second and ride the brake pedal for around 10 seconds at a time and let off (don't lock up the wheels) and repeat again until the drum gets hot. Have a crew check by putting a hand near the drum to check for heat when you pull up to a stop. Then let cool down and you are good to go.

I have been doing this for years and have had no problem bedding them in this way.

Ed