Brake Balance Bar

[Colin Newbold]

see below (again)...its worth the wait!

[Colin Newbold]

I agree with Clive about the measurements he offers, all of which tally with the advice in the leaflet he posted. However, I agree with Andyg that there seems to be insufficent space between the clevis and the central tube for the swivel action to work (that said, Clive's never rear-ended me yet!!). Earlier today, I saw my mate Wil Arif (an accomplished professional race driver with a lot of mechanical nouse) and he said that the vast majority of race cars he sees with a brake balance bar are incorrectly set up.

On Wil's advice, and since these pictures were taken (the springs around each pushrod have since gone by the way - don't ask!), I fitted a 2" washer between each clevis and the central tube just in case the clevis got 'caught up' in the mouth of the tube.




The other mod I made to Gerry's box was as a result of the pivot rod (around which each pedal rotates) coming loose with diasastrous consequences, as those of you on the inaugural 289 Register weekend (Stratford on Avon) may well remember. The rod slipped out, rendering the clutch pedal inoperative. If it hadn't been for the efforts of Dougall and Brian, I would never have got home that day. On my pedal box, the rod was made of mild steel and had no splitpin hole. The net effect of this was that the rod went rusty and bent and eventually slipped out - none of which are desirable! The mod involves two stainless bolts coming in from either end to a threaded centre. The shanks of the bolts are not threaded, allowing each pedal to freely rotate. They are loctited in, and split pinned. In addition, the grease nipples on each pedal shaft ensure free and easy movement.

Colin

P.S. I'd be tempted to question the wisdom of a different size master cylinder on front/back. I eventually went down in size to 5/8 simply to get higher pressure at the wheel cylinders and therefore better brakes. I also have the rear brake line (braided stainless) running through the cockpit (under the carpet) so I could get a brake bias switch close to the handbrake to make final adjustments when out on track.

[andyg]

I have adjusted mine so the balance bar is square when the pedal is depressed. In the relaxed position, the bar also appears square - taking a measurement from the vertical face ofthe footbox to the centreline of the balance bar. On axle stands, front and back wheels appear to lock at the same time. Not sure if you will be able to set the brakes up this way however or whether I need to have it on rollers. As I have said earlier, my front calipers have a bigger demand for fluid (one of th pistons is larger) than Austin Princess, so if you have yours adjusted fully to front and it just works, maybe I dont have the adjustment required.

Andy

[Karl]

Re. Spinners
Clive, I hope somebody in the UK has something for me!
Karl

[clive]

Hi Karl,
Contact James Baxter, he had the same Halibrand spinner set up.



viewtopic.php?f=3&t=409&p=2763#p2763

[Slowjoe]

I also have problem understanding dual brake system.If it is supposed to be adjustable then why drill a hole and roll pin it,surely a locking nut would do.

[clive]

Hi Slowjoe and welcome to the forum.
The brake system is not intended to be adjustable. The reason for fitting the brake bias bar is to provide more effort to the front brakes on the Hawk as the usual Princess 4 pot calipers are not as efficient as the Jaguar rears. If there was no bias bar, then the rear brakes would lock before the front and therefore fail the SVA test.

Section 16.5 Item 5.1 Roller Brake Test of the SVA manual states:-
"A vehicle that incorporates an adjustment device that adjusts the front/rear braking ratio (Longitudinal brake distribution) must be tested in the "worst case" condition, ie maximum rear axle braking.
The vehicle presenter may be required to adjust any such device in order to comply with this condition prior to the brake performance test."

By drilling the nuts and fitting roll pins, this ensures that the bias bar is not "An adjustment device" as it is fixed in position.

[Roger King]

Section 16.5 Item 5.1 Roller Brake Test of the SVA manual states:-
"A vehicle that incorporates an adjustment device that adjusts the front/rear braking ratio (Longitudinal brake distribution) must be tested in the "worst case" condition, ie maximum rear axle braking.
The vehicle presenter may be required to adjust any such device in order to comply with this condition prior to the brake performance test."

By drilling the nuts and fitting roll pins, this ensures that the bias bar is not "An adjustment device" as it is fixed in position.

Unfortunately, it also means that if your brake efficiency front-to-rear is incorrect at test, you presumably will need to retest as if you are 'required to adjust any such device' you will have to remove and redo the drilled pin in the locknuts. Hardly a quick 'I'll do it now' job for the testing station day.

[SJ]

This might be a stupid question, but can the push rods be adjusted in-situ without bleeding the brakes?

[Karl]

Yes, they can. They have no direct connection with the master cylinder piston. You can even take them out.
Regards karl