Brake shoes

BLS
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Re: Brake shoes

Post by BLS »

Bob, good point. I had just thought of that and went out and compared my old shoes to the new ones. The old ones are the straight type on both ends (I have adjusters of both types), but it is easy to see the shoe itself is slightly larger. So, I'll grind a bit off and see how it looks.

Update: Measuring the shoe I find the web of the new shoe is 1/8+ wider than the web of the old shoe with each end sticking out that much more as well. My old shoes are original VW and the new ones are not. Maybe all shoes with the angled end for the adjuster were wider, maybe there is just some difference in manufacturers, I do not know.

Grinding the ends down a bit does the trick. It's just a pain as I'm not sure how much to take off and do not want to go to far, so I had to grind - assemble - adjust - take apart - repeat a couple times.

Thanks,
Barry
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Re: Brake shoes

Post by BLS »

I noticed something a bit disconcerting this evening. Since I have Mike's spindle stiffeners, and I have transferred the old bearings to new drums I had to set up the bearing end play again. No real problem since I learned the last time. Finished up the left front, put the grease cap on with a couple taps of the rubber mallet, and the wheel does not turn freely anymore. :shock: I checked after torqueing the nuts and it was OK. Take the grease cap off and loosen the nuts, still tight. Press the brake pedal and release, voila, it free's up. Hmm, tighten up the nuts. Still OK. Put on the grease cap. Binding again. Press and release brakes and it is OK. One thing to note, the Porterfield shoes and new drums are deadly quiet. There is very little noise when the shoe is touching. Now, the old shoes were the straight cut type, meaning the adjuster screw and shoe are straight across. The new shoes and adjustment screws are the angled type. The screw angle is correct with respect to the shoe. I did notice with these shoes and adjusters that the spring pressure is trying to pull them in one direction slightly (towards the wheel cylinder, the strongest spring). Apparently a good tap and they shift, touching the drum slightly. Pressing the brakes re-centers them. It seems to me that every bump is going to cause them to shift and create a bit of drag.

Anyone else experience this? I suppose I will take it apart and see if I can figure out a way to stop the shifting, but with the angled adjusters and a bit of lubrication at each point (adjuster and wheel cylinder contact), I'm thinking it is forced to move. Any idea's?
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Bob Posner
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Re: Brake shoes

Post by Bob Posner »

I installed my first set of Porterfields and had to grind a little to clear the drum,but experienced no unusual stuff such as you did,so I suspect it is not related to the shoes.
BLS
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Re: Brake shoes

Post by BLS »

Bob, I don't think it has anything to do with the Porterfields, but I do think it is the shoes and angle adjusters. Are you using the straight or angle shoes/adjusters?

It's easy to see what happens. With the drum off and the shoes centered, tapping on the spindle causes the shoes to slide on the angled adjuster in the direction of the wheel cylinder. The return spring is trying to pull the shoes together and only friction is keeping the shoes from moving. If the drum were in place they would stop when they touch the drum. It just lightly touches, the drag is small but it is there. I did grind the shoes slightly per my earlier posts and ground them to match the original angle. On both the unground shoe and ground shoe the angle really doesn't match the angle of the adjuster very closely. I typically grease these contact points lightly. With no grease the shoes do not move, the friction is enough to hold them in place.

I tested this with my old (straight) shoes and straight (no angle) adjusters. They do not move.
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Bob Posner
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Re: Brake shoes

Post by Bob Posner »

My angled shoes fit the adjusters evenly. Could be your issue?
BLS
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Re: Brake shoes

Post by BLS »

Bob, could be. I only have one set of angled adjusters, came with the car. They are definitely a different angle than the shoe. They also have a very wide slot compared to the straight adjusters. I'll have to see what else I can dig up.

Thanks for the help,
Barry
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Re: Brake shoes

Post by FV80 »

It's pretty easy to grind the shoe a tad to match the adjusters correctly. BTW - this is a VERY COMMON problem. It is also different from front to rear since the rear is generally offset 90 degrees from the front. I've had more trouble with the rears since the shoe is "vertical" and therefore tends to slide downward more easily. I've been thinking about rotating the rear backing plates to see if that helps.
Steve, FV80
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BLS
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Re: Brake shoes

Post by BLS »

Thanks Steve. I never used the angled adjusters/shoes before and just assumed they matched. I find the whole thing a bit odd, but I'm guessing on a bug it just didn't make much difference. In any event, I'll work on the ends of these and see if I can get them to quit sliding. Once I take off the grease they don't move so easily :shock:

I see what you mean about the rears. I have not done those. However, gravity would want to slide them down but the adjuster and spring squeezing would want to push them up. Maybe they balance out...

Thanks,
Barry
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brian
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Re: Brake shoes

Post by brian »

If the proper tie down springs and pins are used the orientation of the backing plate will not be an issue. The tapered adjusters, which must be used with tapered shoes, was designed to center the shoe within the drum and is considered superior to flat adjusters. Much of this discussion has taken place several times and could be searched.
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.
BLS
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Re: Brake shoes

Post by BLS »

Hello Brian,

I tried searching and could not come up with anything definitive... Depends upon how you search I suppose.

I think the only question I have left is: Is it normal that angled adjusters and angled shoes do not match? Or, do I have oddball shoes or adjusters or both? The angle of the adjuster and shoes are not even close. This causes the shoe to slide toward the wheel cylinder with the spring squeezing the shoes. Just tapping causes it to break loose of what little friction is holding it. Without lubrication it is better. I will grind the shoes to match the adjuster and am guessing that will solve the problem. I always had the straight adjusters and shoes and I'm beginning to think they're better... The other thing I find odd is the difference in the shoes. The web of the new shoes is about 3/16 wider than the old shoes. Per pair of shoes that is 3/8 greater diameter. The old shoes are original VW shoes, the new ones are not.

What I do have: the correct pins/springs, new drums, new shoes, new wheel cylinders, checked spindles for straightness, angle type adjusters. The first problem was the shoe being wider in the web. The second is the mismatch of the shoe angle and the adjuster angle causing the shoe two slide past "center" contacting the drum lightly.. The shoes are clearly angled, just not the same as the adjuster.

Anyway, I'll learn. Thanks for the help,
Barry
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Re: Brake shoes

Post by brian »

The angles are a bit different and the edges of the shoe tab are radiused and designed to move towards the wheel cylinder under rest. As the wheel cylinder is activated the show moves forward. Besides the apparent difference between front and rear, later model shoes 66/67 were a bit wider and are usually the style sold today. If the edge of the shoe does not rub on the drum, it's probably ok. I sometimes have to grind the outside edge of the front shoes to assure full clearance under heavy cornering.
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.
BLS
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Re: Brake shoes

Post by BLS »

My report of "wider" is misleading I think. By wider I was not referring to the shoe width or brake lining face width, I was referring to what I call the web, the part of the shoe that rests on the adjusters. It might be better to call it height. The height of the shoes were quite a bit more than the standard VW shoes I have, by about 3/16. Add the two shoes together and it is almost 3/8 greater in diameter, which is why the drum would not go on without grinding the "web" at the adjuster contact points. Also, the angle on the shoe contact point does not match the adjuster angle. It has been pointed out to me that it is possible the shoes were hand ground from straight shoes by someone prior to Porterfield getting them, and maybe not grinding them at the correct angle. It's possible. Without VW factory parts in hand I cannot be certain what it is supposed to look like.

In any event, with help from everyone, I now at least understand what I have and will get it to work properly.

I'm not trying to beat a dead horse here, just explain in case someone else has an issue. I appreciate all the help.

Barry
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Re: Brake shoes

Post by FV80 »

Barry,
Seems you've been working on this car for well over a year :lol: Any chance we'll see it on the track this year ?? Maybe Atlanta in a few weeks??

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Re: Brake shoes

Post by BLS »

I was hoping to get to the school in Sav. end of month but work is preventing that. So, Summit Point (end of March) I think or if not, then something with track days to get some time in the car. Atlanta is probably out as I think I will be out of the country.

But, yes this year, as soon as possible. Car has a few details left, paint, new belts, some seating work, nothing big. I still have to get the dang trailer working, rewire lights, new tires, and check/grease wheel brgs, a day or 2 on that. The darn global warming here is making work difficult...
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Re: Brake shoes

Post by BLS »

One last comment. I have looked very closely at the front brake shoes and how they work. I'll start with this comment - It looks like the VW engineers tried to "fix/improve" a crappy brake design with the angled adjusters. For our purposes, I don't think they did that.

The angled adjuster causes the shoe to slide toward the wheel cylinder. It does not "center" the shoe unless the stopping point happens to be centered. However, the stopping point changes as the shoe is adjusted. There are 3 contact points for the shoe, the adjuster, the wheel cylinder, and the backing plate in the very center of the shoe. With the angled adjusters, when pressure is placed on the shoe, it slides forward until it stops by contact of the shoe against a bump out in the backing plate that is very near the adjuster. As you adjust the shoe further out, the curvature of the backing plate bump allows the shoe to move further forward. With the wide width of the adjuster screw slot, the shoe can even ride up over the backing plate unless you have enough hold down spring force to keep it pulled in. The only thing that keeps the shoe from moving until it is stopped by the backing plate or the drum is friction, which increases with spring hold down force. This is what happens with the drum not on. With the drum on the shoe will slide until it hits the backing plate or the drum. My left side shoes were contacting the drum before the backing plate bump, which is what started me on this subject. There was just enough friction to hold them in place until I tapped on the dust cap, at which point the shoes break free and move until they touch the drum. Pressing the brake pedal centers them back up and the drum rotates freely again, until you tap it again.

Just for fun I installed my old shoes and straight adjusters. They do not try to move with spring pressure, they get centered only by the drum when activated.

I'm going to guess the purpose of the angle adjusters is to move the shoe as close as possible to the drum on the wheel cylinder side. On a Bug, I doubt the slight occasional drag would make much difference. Maybe, the backing plate design for the angle adjustment shoes is a different design. I don't have any to look at, but I don't think we can use those anyway. I doubt they are any different.

I do not see any way to really fix this. The only thing I can see that will help is to get the hold down spring pressure at the right amount. So, I am going to throw the pins out in favor of a screw that I can adjust the spring force with and try that.

Please feel free to chime in if I am in error or you have anything to add or you think this comment might be misleading to someone. My hope is it will be useful to someone working with the front brake system. I would imagine the same issues exist at the back but I have not checked it yet. At the moment I have straight shoes/adjusters in the back. Maybe everybody already knows all this and I'm just ignorant, which is pretty likely :oops:

EDIT: I forgot to mention, measuring the shoes I found there was some difference in the angled ends of the shoes. My friend Dietmar mentioned it was possible the shoes were hand ground by someone before Porterfield got them as cores. This would seem to be the case as from shortest to longest (in turns of the height or diameter of the shoe) there is more than 1/8 difference. The shapes are not all exactly the same either. The two I happened to pick for the left front that I started with were different than the other two, not having the correct angle. The second pair matched the adjuster angle very closely. Since they are all too tall anyway, I just had to grind the angles correctly.

Regards,
Barry
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Re: Brake shoes

Post by brian »

Don't forget this design is over 50 years old and I appreciate modern scorn. Even in the 1960's VW brakes were inferior to US systems that were designed for heavier cars. Most drums brakes from that time used dual wheel cylinders and floating automatic adjusters. But for a 2500 # car, they were fine and for our 850# cars, there more than capable of doing the job. Don't forget, we can thank the health concerns about asbestos for our issues with "organic" brake linings.

As the wheel cylinder expands it tends to shift the shoe towards the adjuster. When the adjuster is angled, this movement will force the shoe up increasing the contact with the drums. Hence the "centering" activity.

Thanks for the observation about the shoes themselves being a bit large. I have had conversations with Portherfield tech folks about the lining appearing to be too large for new drums. Now it appears their cores, which appear to be new and not OEM recycles, are too large.

As I mentioned before, and you've discovered, it's very critical to use the right length pins on the tie down springs. I know of one competitor that does exactly what you mentioned and uses small bolts with nylock nuts to set the tension of tie downs. The tension should be firm but still allow the shoes to shift back and forth. Out of habit, I strike the shoe back and forth to confirm it will move properly just before I reinstall the drum.
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 satterley_sr »

Anyone have trouble installing the Porterfield front shoes? My backs went on just fine, the fronts seem to be too big. Tried the angled adjusters, straight adjusters no go. Do they need to be radiused? Drums turned? I put my carbotechs back on and they fit fine.
BLS
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Re: Brake shoes

Post by BLS »

Anyone have trouble installing the Porterfield front shoes?
Yes, the shoes are simply too large. You will need to grind a bit of the metal off to get them to fit. I, and you, are not the only ones to have the problem. Apparently Porterfield's supplier for the shoe itself is supplying them oversized.

Barry
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Re: Brake shoes

Post by fvracer27 »

I know of at least 4 cars including mine will zero problems with them. Work like a charm and stop as good if not better than the CT over priced shoes.

Make sure the adjuster is in all the way and the adjust spring is not holding it out. The shoes should also take angled adjusters I do not think the sell straight adjuster shoes.
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Re: Brake shoes

Post by satterley_sr »

Barry

Can you tell me more about what you had to grind on the shoes.

Dave
BLS
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Re: Brake shoes

Post by BLS »

Dave,

The part of the shoe that fits in the adjuster, the two ends. I believe if you compare them to your old shoes you'll see what I mean, they will be just a bit longer. Perhaps if you have turned drums they will fit (although they would then need to be arched to fit the drum), but with a new drum mine would not fit. An original VW shoe would fit and was just a bit shorter. I did not complain to Porterfield since it was easy to fix. If you read my earlier posts it might explain it as well. I was not the only one with the problem as I heard from at least two others with the same issue.

Oh, one more thing, I asked for and received the angled shoes. They would not fit as described. I ended up grinding them flat anyway for the straight adjusters as I found the straight adjusters to be better.

Regards,
Barry
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Re: Brake shoes

Post by satterley_sr »

Thanks Barry, I'll give it a try. I spent over two hours messing with these things so I think I'll leave the carbotechs on until next time.

Dave
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Re: Brake shoes

Post by jpetillo »

I got the Porterfields last year and put them in new VW NOS drums and they fit fine - angled adjusters. Perfect arch as well. Maybe they're sourcing their cores from a different vendor now, or the shoe material is thicker.
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Re: Brake shoes

Post by jphoenix »

jpetillo wrote:I got the Porterfields last year and put them in new VW NOS drums and they fit fine - angled adjusters. Perfect arch as well. Maybe they're sourcing their cores from a different vendor now, or the shoe material is thicker.
I had the same experience, they fit perfectly. I've flipped them twice now and they show little wear after 7 race weekends (19 hours on the hour meter) - no complaints. I'm not using them very hard (still learning to brake later and harder) but they haven't faded at all, even in Spokane on a warm day.
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Re: Brake shoes

Post by Vorscha99 »

Here is the scoop on Vee shoes. I am not sure exactly which year VW switched from straight slot to angled slot adjusters, but it must have been around 1965.
The straight slot adjuster has a narrow groove, as well as, the wheel cylinder. The backing plate only has one contact point at the pin. This has defined the position of the shoe with three points in space.
Your backing plate needs to be flat in either case or the shoe will be angled at rest, requiring more clicks backed off, so they don't drag.
The angled slot system uses a backing plate with three contact points, the wide groove wheel cylinder and the wide grooved angle adjuster. The backing plate locates the shoe, and the shoe will float in the wheel cylinder and adjuster.
The return springs will pull the shoes against the angled adjuster and force the shoe towards the wheel cylinder which causes drag but gives quicker response in a street car.
These two systems can't be mixed.
I never have drag with the straight slot and Mike at Carbotech has both versions. The XP8 compound is the closest to the old "Green" compound. I just wish that the Kelate material was still available. The new "Greens" are not that material. The old Greens had to be warm to work, but man would they stop! I just threw a set of Porterfield shoes in the trash.
Remember, brakes just slow you down!
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