Balance bar brakes, problematic for builders?

[singlecoil]

A good many kit manufacturers deal with the problem of getting the front rear brake balance right by providing for the fitment of balance bar brakes with twin master cylinders.

However, this gives the amateur builder quite a headache, because he won't pass the IVA unless the bias is correctly adjusted AND the bar is rendered unadjustable in the future by the nuts welded and the bar welded along its length. So the builder is going to have to find a way of getting the brakes adjusted before the test (drive up and down the road outside your house trying wheel-locking stops?) and then getting it all welded (are you SURE it's right?) (have you got a welder?).

Manufacturers might say in their defence that they don't know what combination of discs/drums/calipers that builders are going to use, but do the panel not agree with me that they should research and test at least one combination of these items that will pass with a dual master cylinder, thus freeing the builder from this problem?

[craig7l]

or another option is for IVA stations to offer an hourly paid service for use of the rollers to set the brake bias road legal after you have bedded the brakes in.
Set and weld and then IVA test the very next day/week.

everyones a winner (but a pain in the arse)

[Sam_68]

singlecoil said:

...because he won't pass the IVA unless the bias is correctly adjusted AND the bar is rendered unadjustable in the future

Nothing is unadjustable in the future.

[singlecoil]

Sam_68 said:

singlecoil said:

...because he won't pass the IVA unless the bias is correctly adjusted AND the bar is rendered unadjustable in the future

Nothing is unadjustable in the future.

While that's very true, it doesn't really address the main issue

craig7l said:

or another option is for IVA stations to offer an hourly paid service for use of the rollers to set the brake bias road legal after you have bedded the brakes in.
Set and weld and then IVA test the very next day/week.

everyones a winner (but a pain in the arse)

It may well be that when IVA testing is privatised, that the people doing the tests may well offer to set the bias to the correct standard and then weld it up themselves (for a fee, of course).

Edited by singlecoil on Saturday 20th March 11:22

[Sam_68]

singlecoil said:

While that's very true, it doesn't really address the main issue

Well, the driving up and down the road doing emergency stops is certainly viable - the bias doesn't need to be that accurate, so long as the back locks predictably before the front - or you could get it tested on your local MOT rollers?

I would hope that as the test becomes established, competent manufacturers who supply kits with bias brake kits will be able to give measurements for the bias bar offset and/or (if they're clued up enough) sell you a fixed balance bar manufactured to the correct lengths that will permanently :cough: replace the adjustable item and thus allow you to take the IVA test in confidence.

[Paul Drawmer]

Sam_68 said:

... so long as the back locks predictably before the front...

Err, is that right?

[Milky Bar Kid]

Is anyone else still not overly happy with the idea of having to weld the whole bias bar? Is that really the only way the IVA inspectors will pass them?

Otherwise, until the brakes are bedded in, I don't see how you could really set the brakes up correctly. I know many builders fail the brake effort test due to weak braking effort caused by all new systems. Bar going to a track day or borrowing an old local airfield for the day I don't see a sensible way round it.

[craig7l]

Sam_68 said:

Well, the driving up and down the road doing emergency stops is certainly viable - the bias doesn't need to be that accurate, so long as the back locks predictably before the front - or you could get it tested on your local MOT rollers?

in the wet with a mid engine rear lock up first is always fun...

[Sam_68]

Paul Drawmer said:

Sam_68 said:

... so long as the back locks predictably before the front...

Err, is that right?

Doh! T'other way round, obviously, sorry!

Slight communication problem between brain and keyboard this morning!

[66Quinny66]

It shouldn't be too difficult to get right. Mine went through SVA and had the nut and roll pin solution but I left some (quite a reasonable amount of) adjustment in there. This range was determined by getting someone to watch as I braked in the wet yard at our workshop. As a result, it was tested at both extremes and passed at both of these. However, the tester still put it down as a fail as he wanted it properly locked off. I know that my car is not the same as everyone elses out there but the point I'm making is that I could have picked any point in between my two extremes (about 7 full threads on the bar) and secured it or, for IVA, welded it up.

[singlecoil]

Sam_68 said:

singlecoil said:

While that's very true, it doesn't really address the main issue

Well, the driving up and down the road doing emergency stops is certainly viable - the bias doesn't need to be that accurate, so long as the back locks predictably before the front - or you could get it tested on your local MOT rollers?

Well it's viable in the sense that you could adjust them that way and get a reasonable result, and better if you checked it again in the wet, but not so good from the legal point of view, especially if your neigbours are not all good friends.

[Sam_68]

Well, I guess if it bothers you, you shouldn't fit adjustable brake bias components?

I personally think that it's a ridiculous bit of nanny legislation, but there you go... we're stuck with it, so you either accept that you have to meet the challenge, or else you buy a kit (or braking components) that don't present you with that challenge in the first place.

I assume you're familiar with the 'fixed' balance bar arrangement that uses a flat bar with three holes in it - the outer two holes connect to the master cylinder clevises and the centre hole takes a clevis from the brake pedal? The relative distances between the holes dictate the brake bias. This sort of arrangement always used to be regarded as the 'poor man's alternative' to a fancy, adjustable bias system... you just make up different bars with different hole offsets to suit whatever bias you want according to conditions. As far as I can see, this would be perfectly legal under IVA; manufacturers could supply a bar pre-drilled to give a bias that is IVA-compliant with their pedal box arrangement and if you wanted to swap to an adjustable system afterwards it wouldn't be a big deal.

Like many bits of the SVA/IVA legislation (nut covers; I mean, WTF?!), it's a frustratingly nonsensical bit of bureaucracy, but I'd have thought we're all getting used to not being allowed to think for ourselves by now?

[singlecoil]

Sam_68 said:

Well, I guess if it bothers you, you shouldn't fit adjustable brake bias components?

If and when I get to be a kit car manufacturer, I will offer customers a choice, one particular set of brake components that have been found to have the correct brake balance and passing IVA when fitted, and the possibilty for them to fit a balance bar system and their own choice of brake parts if they are ready to cope with the attendant difficulties

My complaint is on behalf of customers who don't have the facilities to drive the vehicle and adjust the bar as needed, and then weld it up as required. Recently I came across a chaps who is building an expensive kit of highly reputable manufacture, and he didn't even know about the problems caused to him by the manufacturer opting for the simple (to them) solution of the adjustable balance bar. He knows by now, of course.

[King Herald]

Milky Bar Kid said:

Is anyone else still not overly happy with the idea of having to weld the whole bias bar? Is that really the only way the IVA inspectors will pass them?

Do they inspectors condone people welding hither and yon on brake or suspension components? I doubt it very much.

One easy way to test brakes is on gravel, rather than tarmac. Far less wear and tear and noise and smoke, but the results are the same. You just need a bystander to observe what the wheels do.

So, off to the local gravel quarry....

[kdempsie]

I can certainly see why this is a pain to render these items unadjustable but I think the benefit of having adjustable bias is worth it in the long run. As you progress through suspension set ups, in different weather, getting more and more in tune with the car the brake balance def needs adjusted. I changed the spring rates on my car, didn't initially alter the bias and couldn't understand why I was locking wheels all of a sudden. The penny finally dropped and the car feels much better now with adjusted bias.

I'm tempted on a Sylva J15 build at the moment and will go for bias bar braking if I decide to take the kit building plunge again. Initially when I built the first car I felt the way Singlecoil does, that it was an avoidable pain, but it really is a small detail in the grand scheme of the build and another little engineering challenge to solve. I reckon the way Sam68 has suggested with a fixed drilled bar would be a simple home solution that can be retrofited after the test (for racing of course). Or the Rally design bias bars are pretty cheap, destroying one for the test and changing it later would be pretty easy and not too financially painfull either.

[blueg33]

Sam_68 said:

Paul Drawmer said:

Sam_68 said:

... so long as the back locks predictably before the front...

Err, is that right?

Doh! T'other way round, obviously, sorry!

Slight communication problem between brain and keyboard this morning!

OP is now dead. How is your insurance cover?

[66Quinny66]

Sam_68 said:

(nut covers; I mean, WTF?!)

I found it more amusing that my exposed downpipe and cat were checked for sharp edges!

[singlecoil]

King Herald said:

Milky Bar Kid said:

Is anyone else still not overly happy with the idea of having to weld the whole bias bar? Is that really the only way the IVA inspectors will pass them?

Do they inspectors condone people welding hither and yon on brake or suspension components? I doubt it very much.

One easy way to test brakes is on gravel, rather than tarmac. Far less wear and tear and noise and smoke, but the results are the same. You just need a bystander to observe what the wheels do.

So, off to the local gravel quarry....

The welded requirement is actually in the IVA manual (section 09B).

I agree about the gravel, but look at what is involved for the average builder assembling his car int he garage attached to his house-

First he needs a trailer, and a car capable of towing it, and if he isn't old enough to have the right type of driving licence, to take a test to get the correct class of licence, or he needs someone else who has all these things, and the time to help, or to pay them for it.

Then he needs access to a suitable testing area, ideally gravel. Where's the average person going to get that? He needs access to someone's private property (and that includes supermarket carparks), he probably wouldn't even have the car unloaded before the BIB would be round.

But even if he does overcome these obstacles, he's still got to have that welding done. Most kit car builders don't have welding equipment and the skill to use it on hand.

I should say I am not complaining on my own behalf, as I have all these things, but it does seem to me that manufacturers who use balance bars are making it easy for themselves and hard for their customers. I wonder how many of them point out to their prospective buyers the difficulties they face?

[Sam_68]

blueg33 said:

OP is now dead. How is your insurance cover?

Natural selection, Your Honour. Anyone daft enough to believe everything they read on an internet forum...

66Quinny66 said:

Sam_68 said:

(nut covers; I mean, WTF?!)

I found it more amusing that my exposed downpipe and cat were checked for sharp edges!

They really ought to make allowances for self-cancelling risks, don't you think? You might cut yourself, but at least the wound would be cauterised in the process!