Brake shoes

jphoenix
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Joined: July 12th, 2013, 7:41 pm

Brake shoes

Post by jphoenix »

I understand carbotechs are no longer available, so what is being used these days and where would I buy them?
Jim Phoenix
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Re: Brake shoes

Post by FV80 »

CT's *ARE* available - just not the old compound that worked so well for us for many years. CT is working on a new compound that will hopefully be as good or better than the original, but I haven't heard a status report since the Runoffs. I plan to call and talk with them this week and will try to remember to come back and update this thread if I find anything useful.

I have not tried them myself, but have heard that the R4-D brakes from Porterfield work reasonably well. The other option was KFP brakes, but I hear that they are no longer available. So.. it's Porterfield, or the current CT brakes for the moment. The CT's work better than "regular" shoes, but don't quite have the breaking power for some tracks such as Road America or COTA.

Steve, FV80
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fvracer27
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Re: Brake shoes

Post by fvracer27 »

CTs are availible at a premium of $185 per axle and are not the same as old compound

KFP is no longer a option I was in contact with Kieth from Racing Stuff and he did all he could to make the KFP FV shoes happen again but never got there so I tried the Porterfields and was very happy. KFPs would have been around the same price as the CTs

Porterfields are availbile at $109 or $119 I can't remember exactly but they are much more reasonable than the CTs and I can not tell a difference between the 2. I have used the porterfields for a complete season or and I mainly run on a heavy high braking track. I am completely confindent I will get at least another full season maybe even 2 seasons more.
Mark Filip
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jphoenix
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Re: Brake shoes

Post by jphoenix »

Thanks for the info guys, where do you buy the Porterfields? Do any of our sponsors stock them?
Jim Phoenix
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Re: Brake shoes

Post by BLS »

http://porterfield-brakes.com/index.php

But, FV (VW beetle) is not listed so I'm guessing you need to call and order brakes.
Barry
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Re: Brake shoes

Post by jphoenix »

Thanks Barry, I had looked through their site with no luck, so I suppose I'll call them.
Jim Phoenix
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Re: Brake shoes

Post by fvracer27 »

Yes just call they will know exactly what you need. I believe it is online but it's hard to find.
Mark Filip
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Re: Brake shoes

Post by brian »

Their web site leaves a lot to be desired and does not list the vee shoes. A call to them will suffice but make sure you get the race compound, R4D. I paid $119 for each axle. $238 for all four wheels. It may not hurt to let them know if your drums have been turned before and try never to use new shoes on new drums. Condition the drums with old shoes prior to bedding in the new shoes.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
jphoenix
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Re: Brake shoes

Post by jphoenix »

brian wrote:Their web site leaves a lot to be desired and does not list the vee shoes. A call to them will suffice but make sure you get the race compound, R4D. I paid $119 for each axle. $238 for all four wheels. It may not hurt to let them know if your drums have been turned before and try never to use new shoes on new drums. Condition the drums with old shoes prior to bedding in the new shoes.
Good info, thanks Brian. I haven't pulled the drums yet, however I did get some spare drums from Dave as well as a drum go/no go gauge, so I should be in good shape for my novice season. New Torquemeister tool arrived today.

I've been reading all about brakes and steering on this forum lots of good info on setup.
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Re: Brake shoes

Post by fvracer27 »

brian wrote:Their web site leaves a lot to be desired and does not list the vee shoes. A call to them will suffice but make sure you get the race compound, R4D. I paid $119 for each axle. $238 for all four wheels. It may not hurt to let them know if your drums have been turned before and try never to use new shoes on new drums. Condition the drums with old shoes prior to bedding in the new shoes.
What is the reason not to use new shoes on new drums?
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Re: Brake shoes

Post by racing stuff »

As with brake shoes for racing, try never to use new brake pads with new brake rotors. Condition the rotors with used pads (unless you are changing pad manufactures).
Or, condition your drums/shoes or pads/rotors in a dedicated session and not during a race weekends practice/qual. time allotment.
Keith
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Re: Brake shoes

Post by fvracer27 »

How much does it take to condition the new drums with old shoes before you can bed the new shoes in the drums you just condition. I know that sounds confussing but I think I got it correct :lol:
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Re: Brake shoes

Post by BLS »

Assuming we use new drums with new Porterfield brakes and do not have used Porterfield shoes to "condition" the drums, what is the correct procedure?
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Re: Brake shoes

Post by fvracer27 »

BLS wrote:Assuming we use new drums with new Porterfield brakes and do not have used Porterfield shoes to "condition" the drums, what is the correct procedure?

Put them both on together and run it :mrgreen: That's what I had to do and I have had zero problems.
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Re: Brake shoes

Post by brian »

The material on new rotors or drums is considered "green" and needs to be heat cycled to be "seasoned" and able to withstand heat. Maybe an engineer like Bruce L. can explain in detail. If one uses new friction material for this seasoning, the heat may very well get too high and cause "hot spots" or warping of the drum or rotor. One session should be enough to season drums. Like shoes, I go easy on the brakes for most of the session then really lean on them for a couple of laps at the end then let them cool.

Last weekend at Cal Speedway, I noticed someone did exactly that and bedded shoes on new drums and the drums were blue from all the heat. If you notice that the drums are getting really blue, make sure the shoe is fitted properly and there is no drag.

When having your drums turned, which should be done at least annually, have the machinist go for a slow cut and fine finish.

Quite honestly, Road America is the toughest place on the planet for our brakes. We have several front runners that run the Porterfields and while I haven't tested them yet, everyone that runs them appears to be happy with them. Laguna Seca will be much easier.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
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Re: Brake shoes

Post by BLS »

Mark, my question did not really ask what I wanted to know. Somewhere I read that someone (MV maybe) used a toaster oven to "cook" some brake shoes before using them. It wasn't the CT shoes, maybe just standard beetle shoes. So, I'm wondering if there is anything one can do to speed up the break in.

Otherwise, as you said. There isn't much choice...
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Re: Brake shoes

Post by hardingfv32-1 »

'Green or seasoned', these do not sound like metallurgy terms that can get us to a specific metallurgical goal. More like FV mythology. Do the drums need hardening, annealing, etc. for example? First we need to know something about the metal involved and what procedures have been already applied. Next we need to know what the new target is. None of this information is generally available to us. Even if you get beyond this point you must follow exacting procedures related to temperatures and application rates to get the correct results.

Just more myths....

Brian
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Re: Brake shoes

Post by brian »

MLS, you do not need the same friction compounds to bed in the drums. Any used shoe that fit will work.

I really didn't want to spend a lot of time boring everyone with the all the details, but why do new or recently turned drums be bedded in like shoes? The force exerted by the shoe against the drum tends to be concentrated on the centerline of the shoe. Why? because the web behind the shoe that attaches to the adjuster and wheel cylinder, acts as a reinforcement and the edges of the shoe apply slightly less pressure on the drum. The center pressure shapes and conditions the drum friction surface into a slight curve and transfers small amounts of friction material on to the drum. If too much heat is generated before the drum has been shaped or bedded in, the heat in the center of the drum will be very high and cause hot spots and warping.

Another factor to consider is that the leading shoe is doing most of the work and generating more heat. The trailing shoe is reacting to the hydraulic back pressure generated by the leading shoe and applying slightly less pressure. This creates variable heat zones for the drum to pass through. Disc brakes go through a similar process that is caused by the pads rocking and creating a leading edge on the pads. Many times you will see different piston sizes on multiple piston calipers to minimize this behavior.

High end suppliers like those found in NASCAR, do all this work prior to shipping pads and rotors to the racers. Those racers do not have the time or desire for bedding components but they pay for the privilege of having it done for them. It takes some expensive equipment to dyno, yes dyno, and break in components.

I guess if you're patient enough, you can bed new shoes and drums at the same time but it will take more time. In my 50 plus years of doing brake jobs, including being owner of a 9 bay, retail brake and alignment shop, I have always advised customers to go easy on their new brakes for 50 miles. Racing is even more critical. I prefer to use a practice session for bedding my brakes. Go easy on the brakes for all but the last couple of laps and you'll be fine. Just make sure the shoes fit the drums before installing them.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
hardingfv32-1
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Re: Brake shoes

Post by hardingfv32-1 »

Go easy on the brakes when new to reduce the formation of hot spots on the drums and shoes. Simple as that. Same as breaker-in for piston rings and cam shafts.

"The center pressure shapes and conditions the drum friction surface into a slight curve and transfers small amounts of friction material on to the drum."

How does the 'center pressure' shape the drum friction surface? Bending or material removal?

How is the drum 'conditioned'? Heat treatment process or transfer layer (TL) formation?

Little is know 'scientifically' about the benefits or problems caused by the TL. Most research has focused on brake noise. The formation and maintenance depend on many factors, materials used, pressure, heat, brake application time period, etc. Assuming you know what you want in the way of a TL, you would need to control the previously stated variables to get the desired TL. The NASCAR teams attempt to control the initial bedding and TL formation by having it done on a brake dyno run to set specifications. Many teams have their own specifications. That fact is we do not know what their targets are. Regardless, we do not have any control over the break-in variables if done on track nor do we have knowledge of the materials involved. Talk of anything beyond the bedding the of brakes is pure myth.

Brian
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Re: Brake shoes

Post by BLS »

I appreciate the information.

I just ordered RD-4 front shoes from Porterfield. The nice lady that answered the phone knew what I wanted. Easy.

I have a set of drums and shoes from my old days. The Ferrodo linings I have are new even if very old stock. The drums I have were turned (max I think but have not measured). When I adjust the brakes I get a ticking each revolution that I do not like, indicating the drums are slightly out of round. To get rid of the ticking seems to be too much adjustment, so I'll try new drums and use the RD4 shoes with those. I'll save the others for spares.
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Re: Brake shoes

Post by joekarter »

brian wrote:Just make sure the shoes fit the drums before installing them.
This is all very good information. Thank you all! From my point of view as a new FV driver and doing my first set of shoes on the vee it has been a big help.

Brian, can you expand your thought a little on the quote above. How is this acomplished (sorry to all of you who already know how to do this :oops: )? I would have thought that purchasing shoes from Porterfield made for FV racing would fit our drums "like a glove".
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Re: Brake shoes

Post by BLS »

"like a glove".
If you have standard drums and standard shoes they should be a perfect match. If the drum has been turned the shoes must be arced to match. Porterfield may do this, I did not ask since the shoes I ordered will go on new drums.
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Re: Brake shoes

Post by brian »

Two steps are required to confirm that the shoes are matched to the drum. Place the shoe in the drum and squeeze down one end and check the gap on the other end of the shoe. If this gap exceeds more than .020 to .030 some of the shoe will likely not hit the drum and reduce surface contact area. I prefer .010 clearance and beveled friction material on both ends of the shoe. A large end gap indicates the shoe is too small for the drum and is likely when the drum's been turned a couple of times. If the shoe does not rock back and forth, check the center of the shoe with a feeler gauge. Any clearance in the center of the shoe should be avoided and indicates the shoe is larger than the drum. Careful use of a belt sander and mask will allow for home remedies. Most arching machines have been made illegal for use in commercial shops but some careful sanding can reduce the issues.

As I mentioned before, it takes a lot of expensive equipment to bed in brakes to a very specific criteria and most of us don't have access to any of that equipment. But that doesn't mean that there are not benefits to our "informal" bedding. Virtually every shoe manufacturer recommends a bedding process be done. If you think the effort is a myth then don't do it.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
jphoenix
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Re: Brake shoes

Post by jphoenix »

joekarter wrote:
brian wrote:Just make sure the shoes fit the drums before installing them.
This is all very good information. Thank you all! From my point of view as a new FV driver and doing my first set of shoes on the vee it has been a big help.

Brian, can you expand your thought a little on the quote above. How is this acomplished (sorry to all of you who already know how to do this :oops: )? I would have thought that purchasing shoes from Porterfield made for FV racing would fit our drums "like a glove".
I'm glad you asked Troy, I'm having all the same questions. Just got the brakes bled tonight after replacing the rear brake lines - lotsa good info on this forum!
Jim Phoenix
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Re: Brake shoes

Post by jphoenix »

Looks like I'm in for a complete brake job, pulled the right front drum this morning after bleeding the brakes yesterday. I suspected the shoes were not adjusted properly because of two things: 1 - the front brakes would move quite a bit while bleeding them (I bled the fronts before the rears, so the pedal was free to move on the fronts only. After bleeding all of the air out, there was almost 2" of travel in the pedal and I could hear the shoes moving quite a ways inside the drum. And 2 - looking for the adjustment holes, I discover there are none :cry:

Image

So, not surprising when I remove the drum and find upper shoe worn badly on the leading side and the lower shoe worn in the center, but not on the ends as shown below. It appears these shoes are worn close to limit, but I'm not sure. In any case, I'll be ordering new shoes because I think I'm going to need new drums as well.

Image

Image

Image

The big question is where do I find new backing plates with adjustment holes in them, or do I simply drill adjustment holes into the existing backing plates?

The right front drum is about 231.4mm measured under the (significant) lip, I believe the limit is 232mm in the front - is that correct for an FV (that's what it says on the drum. I suspect, once turned, there won't be much left, so I'm looking for a recommendation on whether these drums should be replaced or if they have seasons of racing left, I simply have no idea. SR Racing has front and rear drums, but I see Richard Pare has drums available - are these the same? Is one preferred over the other?

Image

With my luck so far, the rears are probably toast since they have been doing most of the work.

I think the brakes are the last unknown on the car that I haven't completely disassembled, cleaned repaired and reassembled. Engine is back from Noble with new heads and pistons (one piston was cracked in half), rod and case bolts were stock, now it has ARP studs and bolts, new clutch and plate, plus a few thousand other little things - it's in and running nicely. Only the transmission hasn't been apart, but it was overhauled last season, so I hope it's OK. Still a couple of months left before school starts!
Jim Phoenix
2016 Red Mercury FV 44
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