Alternatives to the Sierra caliper for Trackerjack brakes.

[GrahamFountain]

Considering what Jon and others have said about the importance of the LSV, I went and had a proper look at the description of the LSV in the ROM (section 70-25-00). Does anyone need the diagrams putting up here? From that description I see that initially and when there's enough load in the back or the car's on a big enough incline, the LSV lets the normal hydraulic pressure into the rear wheel cylinders. So, in that case, the front and rear brakes just have the brake balance ratio set by Triumph between them.

But when the linkage isn't pushing the LSVs piston up, the LSV limits the hydraulic pressure to the rear wheel cylinders to a fixed value. That will mean a fixed maximum brake effort from the rear wheels, however hard you press the pedal, and even if you have legs like Geoff Capes (is that showing my age?)

So does anybody have an idea what value the LSV fixes the rear brake effort at, with the rear brakes in tip-top condition, when there's no load in the back of the car (and it's not on an incline) so the linkage from the rear axle isn't pushing on the LSVs piston?

Graham

[sprint95m]

Considering what Jon and others have said about the importance of the LSV, I went and had a proper look at the description of the LSV in the ROM (section 70-25-00). Does anyone need the diagrams putting up here? From that description I see that initially and when there's enough load in the back or the car's on a big enough incline, the LSV lets the normal hydraulic pressure into the rear wheel cylinders. So, in that case, the front and rear brakes just have the brake balance ratio set by Triumph between them.

But when the linkage isn't pushing the LSVs piston up, the LSV limits the hydraulic pressure to the rear wheel cylinders to a fixed value. That will mean a fixed maximum brake effort from the rear wheels, however hard you press the pedal, and even if you have legs like Geoff Capes (is that showing my age?)

So does anybody have an idea what value the LSV fixes the rear brake effort at, with the rear brakes in tip-top condition, when there's no load in the back of the car (and it's not on an incline) so the linkage from the rear axle isn't pushing on the LSVs piston?

Graham

Back to basics, is an LSV is actually necessary?
Or to put it another way,
why did none of the other makers using the same front/back combination as a Sprint fit one?

In 1973, this brake combination was hardly state of the art, so to speak, Ford had used it on the Cortina mark 2
(which by that time had been some three years out of production).



Ian.

[GrahamFountain]

The TR7, at least, had a control valve that wouldn't let the rear cylinders get any hydraulic pressure until after the front brakes had taken up all the movement. It was also supposed to stop the rear wheels from locking first. But the CofG of the 7 won't change much from passengers in the rear; though there're a few who reckoned it handled better for a hundredweight of sand in the boot.

Graham

[trackerjack]

Considering what Jon and others have said about the importance of the LSV, I went and had a proper look at the description of the LSV in the ROM (section 70-25-00). Does anyone need the diagrams putting up here? From that description I see that initially and when there's enough load in the back or the car's on a big enough incline, the LSV lets the normal hydraulic pressure into the rear wheel cylinders. So, in that case, the front and rear brakes just have the brake balance ratio set by Triumph between them.

But when the linkage isn't pushing the LSVs piston up, the LSV limits the hydraulic pressure to the rear wheel cylinders to a fixed value. That will mean a fixed maximum brake effort from the rear wheels, however hard you press the pedal, and even if you have legs like Geoff Capes (is that showing my age?)

So does anybody have an idea what value the LSV fixes the rear brake effort at, with the rear brakes in tip-top condition, when there's no load in the back of the car (and it's not on an incline) so the linkage from the rear axle isn't pushing on the LSVs piston?

Graham

Back to basics, is an LSV is actually necessary?
Or to put it another way,
why did none of the other makers using the same front/back combination as a Sprint fit one?

In 1973, this brake combination was hardly state of the art, so to speak, Ford had used it on the Cortina mark 2
(which by that time had been some three years out of production).



Ian.

Probably because no other manufacturer made a car with huge rear brakes and teeny weeny saucer size front discs, also explains one reason that BL no longer exist.

[GrahamFountain]

teeny weeny saucer size front discs

Even for BL, the Sprint's front brakes seem a bit small. The TR7 front brakes give about 30 percent more effort for much the same weight of car. And the TR8 and TR7 Sprint front brakes give about 42 percent more, and would give about 22 percent more on the Sprint discs.

Graham

[Boost All The Dollys]

teeny weeny saucer size front discs

Even for BL, the Sprint's front brakes seem a bit small. The TR7 front brakes give about 30 percent more effort for much the same weight of car. And the TR8 and TR7 Sprint front brakes give about 42 percent more, and would give about 22 percent more on the Sprint discs.

Graham

Would the Tr7/8 brakes mount into the sprint uprights? Or are they completely different

[GrahamFountain]

I've got a set of TR8 callipers (actually, they're TR7 Sprint ones, but they're the same) in the shed. When I've finished doing the spuds, I'll go get and photo them, if it'll help.

Graham

[GrahamFountain]

That went horribly wrong. But here are a couple of photos. I've kept them as much out of sentiment as expecting to use them, so they were just taken off the car that had been professionally mistreated by BL and then did perhaps 150k miles after a resto, about 12 years ago and kept in a plastic bucket in the shed ever since. So don't complain if they look knackered.



Graham

[Carledo]

That went horribly wrong. But here are a couple of photos. I've kept them as much out of sentiment as expecting to use them, so they were just taken off the car that had been professionally mistreated by BL and then did perhaps 150k miles after a resto, about 12 years ago and kept in a plastic bucket in the shed ever since. So don't complain if they look knackered.



Graham

So these extremely rare calipers have bigger pistons and slightly bigger pads than a Sprint. Used against a Sprint disc they will give a 22% improvement (approx) over the originals. No one is even sure they will fit.
They will still have no effect on fade whatsoever, unless to make it even worse and are less than half as much better than A TJ conversion (from your own figures Graham) which DOES combat fade very effectively.

The factory's decision to use the milk bottle top discs and tiny calipers from the Sprint's 1300cc brethren is as flawed as the decision to use the massively oversize TR4 rears and was probably taken by the accountants and not the engineers. If you think this is unlikely, Google Ford Pinto!

Steve

[sprint95m]

Probably because no other manufacturer made a car with huge rear brakes and teeny weeny saucer size front discs, also explains one reason that BL no longer exist.

Ford, Rootes, Vauxhall all that the little front/big back brakes combination!
That was before the Sprint was introduced.





Ian.

[Carledo]

Probably because no other manufacturer made a car with huge rear brakes and teeny weeny saucer size front discs, also explains one reason that BL no longer exist.

Ford, Rootes, Vauxhall all that the little front/big back brakes combination!
That was before the Sprint was introduced.
Ian.

I've just had a thought about that, it seems to me that you can get a pretty big brake drum under a 13" wheel, but not such a big disc. In the end, the wheel is the limiting factor. In the 70s, even supercars (or what passed for them) didn't have vented discs so you can't blame BL for that!
So why DID all the major manufacturers of mainstream cars decide (almost simultaneously) that 13" wheels was the best way to go? This trend started in the late 50s and lasted till the early 80s (and longer on poverty spec motors) Now, even my daughter's el cheapo spec 2013 Corsa has 16" alloys over it's 9" discs!

Steve

[GrahamFountain]

Calling the TR8 discs "less than half as much better" is making a value judgment that I don't think can reasonably be supported.

I say that because there will be some value of upgrade in brake effort that is ideal for you, and probaly different for me. But it's still how far from and which side of that ideal that any brake upgrade takes you that determines how good it is, never some simplistic "biggest is best" approach.

I think, if you stop and look at the problem rationally, it should be clear that the value of the brake upgrade that's ideal for you will depend on how much you upgrade (or are going to upgrade) the tires by, so that you can actually stop in a shorter distance, and how much easier you want it to be to press the pedal to get the wheels to lock.

It should also be clear that if you upgrade the brakes by more than you upgrade the tires, the extra does not shorten the minimum distance or time you stop in; it just means you have to press the pedal less hard to do it. Actually, it's a fact (not a theory) that upgrading the front brakes without upgrading the tires increases the minimum stopping distance and time, not reduces them.

Me personally, I can see the advantage in upgrading the tires and the brakes to stop more quickly. And I can see how to work out what upgrade in brakes matches what upgrade in tires, how much is counteracting the reduction in the safety margin between actual and prefect balance, and thus how much of the upgrade is doing nothing other than just softening the pedal. I can also see the advantage in vented discs to postpone fade; though it's not one of my, undoubtedly, many problems. Maybe I can see why you might want to lose the load sensing valve; though, again, I don't want to. But what I don't actually see is the advantage in that softening of the pedal just so it's easier to lock the wheels.

Graham.

[Galileo]

Probably because no other manufacturer made a car with huge rear brakes and teeny weeny saucer size front discs, also explains one reason that BL no longer exist.

Ford, Rootes, Vauxhall all that the little front/big back brakes combination!
That was before the Sprint was introduced.

Ian.

Can't agree more, if you head over to forums belonging to other cars of the same vintage you will find people complaining about braking, and then usually coming up with some hybrid Ford Sierra/Wilwood caliper solution. Between the Sprint and my Fourtrak I'm so used to a heavy handed approach to braking that when I use a fleet car I need to unpeel my eyeballs from the windscreen the first time I brake...

[Carledo]

Graham, I took the "less than half as much improvement " from your own figures in another thread, where you worked out, with the same built in errors (if any), that the TJ conversion gives an improvement of approx 54% over stock Sprint brakes. If the TR8 calipers on Sprint discs gives 22%, I call that less than half.
Not to mention the fade factor, where, I would guess that bigger and better calipers would heat a tiny, wafer thin Sprint disc to fade point even quicker than the standard setup.
With premature fade being about 80% of what is wrong with the factory brakes, vented discs of some sort is an obvious priority, even the factory acknowledged this with the primitive vents and spaced calipers they used on the touring cars and rally cars. I think Ken Clark (or someone like him) produces a replica of this setup. It's mainly for homologation purposes for classic Touring car racing and very expensive, but it would give you what you seem to want, the same efficiency as standard but less fade.

I really cannot understand your insistence that the TJ conversion is "too good" when you have not experienced it for yourself and those who have, myself included, are completely convinced that it is "just right". I know what theory says, but any scientist worth the name will say theory is useless unless tested and proven in the real world. I guess tyres must have been improved over the years too, because the tyres I am currently using are OK but nothing particularly special.

This will be my last post on this subject, since we seem unable to agree on any level, but I will leave this parting thought. I hate the idea of the "emergency stop", to me it is an admission of incompetence, I obviously have not been paying attention and/or not reading the road far enough ahead if I have to make one.
Last week, for better or worse, the situation arose for the first time in more than 18 months since I installed my TJ kit. I was dawdling through my village, going from home to my workshop, my brain as close to being in neutral as it ever gets, when a Transit pickup in front of me stopped suddenly for no discernible reason, showing one faint and muddy stoplight in the process. By the time I had processed this, I was left with no alternative but to jam the anchors on. The front brakes locked, momentarily, but the rears didn't (no LSV but a PCV from a Cavalier on the rear brakes) and the car stopped in time and in a straight line. The lockup did not surprise me since I was doing 30MPH or less and I must have instinctively eased the pedal pressure when it did lock since I have no conscious memory of doing it. Overall, in these extreme circumstances, I am delighted with how the TJ kit worked.
I have today been driving a BMW Mini Cooper which was horribly overbraked, even looking hard at the pedal had my body trying to head for the windscreen! I know which brakes I prefer!

Steve

[trackerjack]

Just prowling through Ebay and found these which are perfect if doing my vented brake conversion.
http://www.ebay.co.uk/itm/ford-fiesta-S ... SwKOJYGMIU