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Brake Shoe Lining Materials
#11
(30-10-2018, 08:17 PM)Steve Jones Wrote: So, lets get this right. What you're after is 'someone' to carry out an independent test of brake materials. Off the top of my head that's standard 1" and  standard 1.25",  with soft grey material, hard grey material, soft woven material, hard woven material, green gripper, kevlar base and anything else anybody can come up with. Repeat for semi Girling, full Girling, hydraulic with early drums, hydraulic with semi Girling drums, hydraulic with full Girling drums, coupled brakes, uncoupled brakes, fully compensated brakes etc. etc etc. Perhaps when that's been done another 'someone' could do the same to decide what oil to use.

Sorry mate, these are Austin Sevens, not Formula 1 cars.

Steve
No I didn't mean that, but I think that it's just one of the ways the forum is set up that we are all terribly positive about what we like, but don't give reasoned explanations as to why we got to that way of thinking... perhaps partially as we don't want to offend anyone who might sell such a thing that we personally have moved away from or rejected.

As to Formula 1, I would have though that a good few of you involved in Austin 7 competition are using as rigorous a personal method of assessment of your performances and running efficiency, but just at a more common-sensical level? And all that stuff helps us lesser mortals when we are trying to obsess about absolute efficiency in our own petty and trivial ways. Rolleyes
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#12
(30-10-2018, 09:33 AM)Matt_Harnden Wrote: Hi,

I want to maximise the braking on my 7 special for normal road use. One of the items I want to improve and replace are the brake shoe linings.

What experiences have people had with different lining materials?

I’m torn between changing the linings myself (which I have done before) or having them replaced by a company such as Saftek.

Other posts have suggested that the Saftek ‘Green Gripper’ is the way to go - has anyone any experience of this material? Is it worth the small additional cost?

Thanks.

Matt
Back to your question Matt.

I always use Saftek green gripper it is outstandingly good as Steve Jones suggests.
It does not cost more.
My view is that it is not worth messing about fitting the linings yourself Saftek do it so well.
On the alloy shoes I have mine both bonded and riveted. On the steel shoes bonded only.

Clearly the brakes will only work well if all the mechanical aspects are spot on.

A new member of our group (Peter Chaplin) has just done the brakes on his PD tourer, he asked me to test the car as he is new to Austin Sevens. The brakes on his car are really fantastic - Saftek liners and Peter did a brilliant job on the mechanics.
Cannot be beaten in my opinion !

It's a no brainer.
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#13
Hi all,
Nick is spot, on before worrying about the type of material all the Mechanical parts must be setup properly ie remove any play in linkages between pedal and shoes, also that the drums are in good condition with the linings having the same radius as the drums.

Colin
NZ
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#14
I stuck some wet and dry to the inside of an old drum and used that to sand the shoes and linings to make sure the radius was correct as Colin mentions. I seem to remember also filing a chamfer on the leading edge of the linings to prevent them catching.

Simon
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#15
We are very lucky to have access to almost all brake components, new, today. The new drums from Tony are a recent addition and well worth fitting in my experience.
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#16
+1 for Tony's drums
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#17
This  is another recurrent topic. These posts are likely to come up in Search so a summary may be of use to some....
 
Conventional modern lining materials are designed to not fade under very severe use, and to last forever, and to be power assisted. These linings are hopeless in an ordinary Seven. But likely to be applied by brake firms who do not do a lot of old car work.
 
Contemporary brake performance was poor (often abysmal. Some did not achieve 50%!) and even many of the older materials are dubious (I have NOS woven asbestos era Ferodo GG7 linings and roll of the same from 1960s and occasionally see in swapmeets; dunno how this is rated relatively now?)
 
The current specialised soft linings by most accounts seem a major improvement. Locked wheels are claimed. In the dry! A relative rating would certainly be interesting. Various methods of testing by applying to just one shoe can be devised.
 
Bedding is a problem with Sevens, especially with the low mileage. Unlike most other makes the shoes are not free to locate themselves in any way so even if ground to appropriate radius off the car unlikely to seat immediately. Fitting in place to the drum is about the only way of hastening bedding. (I hate to think how much asbestos I sniffed up fitting brake shoes years ago; something to be aware of esp with NOS). The ends of the shoes may need alteration. There have been numerous posts about devices for checking shoe location and for contouring.
 
There is a mod of the shoes to render them partially self locating but it is somewhat barbaric, and might lead to grabbing or rubbing problems. Certainly need to avoid the latter with a Seven!
 
For those new to the topic Seven brakes are not too small. Except perhaps the very last rod brake models, problems arise from limited leverage, little compensation, and lack of self servo effect. If the leading shoe starts to apply itself pressure from the cam reduces and the cam cannot follow up and maintain pressure because it is restricted by the trailing shoe which has no self operating effect and in consequence a relatively weak action. With hydraulic and full Girling sytems the expander follows up and maintains full pressure on the leading shoe.)
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#18
Just got the shoes off the car. The current brake lining material is a very dark brown colour and appears to be absolutely rock hard. The shoes are very shiny and there is very little dust.

I’ll report again once the new, softer material is used.

Matt


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#19
I got the shoes back from Saftek today with the Green Gripper linings. Looks much better than the very hard black material that was on there before. I’ve also had each end of the lining chamfered as recommended by this forum.

My only disappoint is that they have bonded the linings rather than riveting them to the shoe.

I will report back once the brakes are back together and I’ve done a test drive.


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#20
They may be bonded but just think of all that extra brake shoe area you get not having the rivets !!! (every little helps).
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