Front Brake Lining Material

[prelit]

Hi guys,

 

I've just fitted a Gremica 125mm front hub to a Bantam to try to improve the braking power over the previously fitted Montesa 110mm hub.

The hub had very little wear, max dia was measured at 125.5mm and surface was free of any damage, I used a new NOS brake plate and cam assembly with oversized shoes arched to to fit the hub. The lining material was recommended by Villiers Services to be the best for trials. I also opened the brake plate spindle hole 0.020" to allow the plate to centralise with the brake on before tightening the spindle.

Now what I expected was a significant improvement in braking power but in fact the braking is no better!

New wheel bearings.

New cable. Domino levers.

 

Now I've only been up and down the road dragging the brake on but I expected more. I quickly dropped the wheel out and looked at the linings, it looked as if the contact area was good judging by the shine on the shoes as the material was matt after machining down to size. So I chalked the linings and repeated, sure enough the contact area was good with 100% contact. A few more trips up and down the road dragging the brake on to try and bed in resulted in no better performance. I was also alarmed at how cool the hub was too the touch.

 

The lining material is a grey colour, very soft and when machined produced a fine dust. It machined real easy and I just had to keep the tool dressed to produce a nice finish. The hub surface has been bead blasted.

 

Anyone else used this lining material?

Is there any better material available?

I have the NOS shoes that came on the brake plate, these obviously aren't arched to the Hub Dia. but maybe they will be better. They look a more course lining and are brown.

Any other comments?

 

Thanks,

 

Prelit.

[bashplate]

I've not tried this stuff....but some one told me to try fork lift brake material. no idea what colour it is or if it works, but might be worth a look.

 

[2stroke4stroke]

The stuff I was recommended was for use in underwater cranes - action is similar to putting a bar through the spokes.

[bobber job]

Did a quick search based on the above two posts came up with these places, might just have suitable lining material.   This is a subject i need to look into brakes on some of our bikes are poor  finding an effective material would be good.

http://www.saftek.co.uk/contactus.html

 

http://www.bcafrictionmaterials.com.au/products-brake-relining/woven-roll-lining

 

[timdog]

Did Villiers services do the re lining or recommend some material. I have two bikes with shoes relined by them using their trials compound, bultaco chrome hubs, a cub hub and ajs stormer hubs. They are all v good for drum brakes and can stop dead on a fairly steep hill. The lining was a beige colour

[prelit]

Hi Guys,

 

Thanks for the replies,

 

The latest is if I chalk the linings the first few applications are really good, nose wheelies no problem, good feel, just what I wanted. However, this is short lived.

I spoken to Villiers Services who have said that from time to time they do get a hub that don't work with this material for no reason. They recommended to bed the shoes in more and try and transfer the compound onto the drum.

Alternatively they have a woven material that they have good results with. However, this material not easy to machine if you have the shoes done oversize. It is possible if you know what your doing. This material is a beige colour. It quite course with metal particles embedded in it.

I've used this material in the past without arching to the drum on the Montesa hub, although the braking power was better I felt they lacked feel and were grabby.

Someone mentioned he used to wet the hub prior to a trial and this helps calm the grabby feel. 

 

I'm going to try the NOS lining next, I will shoes currently fitted lined with oversize woven material and machine back to dia.if the results are still poor.

I will report back.

 

Thanks again,

 

Prelit.

[prelit]

Hi Guys,

 

Brake with NOS lining are slightly better despite not been bedded in. However even with chalk on they don't bite like the first few applications with the chalk on the Villiers Services supplied lining. No where near 100% contact at present.

 

Timdog, are the beige lining you've had success with woven? These have metal (brass wire?) embedded in them. If so were they arched to fit the hub dia. by machining down from oversize before fitting? If not did they bed in quickly?

I believe the grey material one's supplied are what are used in fork trucks.

 

Cheers,

 

Prelit.

[pschrauber]

Just to make sure:

What cables did you mount?

There are cables around where the wire is OK but the cable hose which is basically a metal spiral with a plastic coating at the outside.

When you engage the lever most of it's energy is used by pressing the metal spiral together instead of engaging the brake.

My personal favorite for cable are:

- Swiss Hortz cables or

- Venhill cables with thick wire.

I never had problems with NOS brake shoes and also in my experience they work best just a tiny bit better then anything you get made from today probably because they have still as best inside? (I use a mask when working to my brakes as the dust ... can be very unhealthy).

[still trying]

A small machining hint;

I use either a plastic coke bottle with a small hole in it, or an old cleaner spray bottle and squirt water on the cutter/lining to keep dust down, as the particles can hang in the air for long periods. Still use a mask as well.

[prelit]

Hi Guys, 

 

Thanks for the tips,

The brake cable is a self made new (Venhill). I went up a size in core wire. The outer cable has been kept as short as possible and the abutment point made stiff. I tried to fine a length of pre-stretched inner but couldn't obtain any. So I don't think the I have too much energy lost to flex./compression.

I did extend the operating arm with 2 extra clevis points. plus 10mm & 20mm. I've tried the standard length and the plus 20mm and it makes little difference. Obviously the plus 20mm point gives a mechanical advantage the expense of a mushy feel.

I was told if I try to machine the woven material to use brake cleaner to keep the tool cool and use a high speed.

 

 

Thanks,

 

Prelit

[b40rt]

What brake plate are you using ? If it's a Fantic 300 it has different shoes from most other grimace brake plates.

[woody]

I've used the beige woven linings, had them done by both Villiers Services and another brake specialist in Blackheath (Midland Brake Linings I think)

 

I had them oversize and I've been able to turn them down no problem and I'm no engineer - don't even know what tool or tip, or whatever they're called, I've used, I've used several different ones as I've done about 20 pairs of these over the years. If I can machine them, then anyone who can use a lathe can.

 

95% of the time they work  fine and stop well even when wet but on a couple of bikes they don't bite so well - one happens to be a Grimeca hub although the other Grimeca is fine.

 

I've never bothered with oversizing the brake plate hole as I just don't understand how that's supposed to work. If the shoes are machined to the hub whilst in a slightly open position, surely that isn't necessary anyway?  I've found off the shelf shoes pretty ineffective and the linings are that thin they can't be machined to enable full contact as they go over the cam if they are

 

 

EDIT:  Just seen your last post.  Not sure what you call high speed but I think I used about 800rpm which I think is on the slow side?  Didn't use brake cleaner or anything to keep them cool and only had one snag moment in all I've done. Lots of brown dust though...

Edited August 11, 2016 by woody

[prelit]

Again thanks for the responses,

 

B40rt, The back plate is Fantic but not the 300 floating cam type which have different shoes as you say.

 

I'm going to send the shoes back and have the done in over size woven material and try to machine them back to hub dia.

In the meantime I going to make up a cable with pre stretched 2.5mm stainless wire core if I can obtain some. This can't do any harm.

 

Woody, I guess the surface speed at 800rpm is quite high at a 125mm dia.

 

The standard Venhill universal front brake / clutch kit uses a 2mm inner cable, does anyone know what the standard Fantic / SWM etc inner cable dia was? Currently my cable is 2.5mm but the 'rope' type rather than the 'wire' type. I believe the rope type to offer more flex but also will be prone to more stretch.

 

Cheers guys,

 

Prelit.

[feetupfun]

This is a fascinating subject. I am greatly enjoying reading about people's experiences.

My 2c worth at this point is that the flatness and surface finish of the hub surface is a critical factor with new linings. Because of what you found with your chalk test I'm wondering if maybe the bead blasted finish on the hub surface cannot hold enough friction material

[prelit]

Ok guys some feed back and thanks for all the interest.

 

I made up a 2.5mm 'wire' cable rather than 'rope' however it was galvanized rather than stainless which I believe is slightly stronger but does have the advantage of been easy to solder with normal flux etc. It also wasn't pre-stretched.

This made a good improvement to the feel at the lever but didn't noticeable give me any extra power or bite. I was thinking at one stage of trying 3mm wire but now l don't think it will offer much more improvement, Anyone using 2mm core currently may benefit from going up a size, just make sure it's wire not rope.

 

So I carried on with the NOS shoes and slowly sanded down the high spots. I must have chalked the shoes 10 times and this got me close to full contact. The cam has to more more than ideal to take up the clearance but it would have to do as the lining weren't oversize to start with.

I then cleaned the hub and shoes with brake cleaner and gently tried to bed in rather than the normal dragging the brake whilst you just ride round. So up to speed and brake fairly hard down to near stand still and repeat several times. Allow to cool and repeat the process again. 

So rather than 'glazing' the shoes this bedding 'should' if you believe the theory transfer some friction material to the drum surface. 

 

Well the result was encouraging, although the brake at present isn't as good as I hoped for it is a vast improvement over the Montesa hub and a vast improvement over the first installation. Slow speed nose wheelies to position the back wheel are now possible.

I'm still going to try the woven material arched to the hub, I hoping the grabby feel will help rather than hinder.

But first I may re try the shoes Villiers Services did just to see if the bedding procedure was a fluke or not.

 

I will keep you informed.

 

Thanks guys,

 

Prelit.