Minispares adjustable brake bias valve

[66S]

Hi guys,
While bleeding the brakes on my '64 race car, I don't seem to be able to get much fluid through the rear and although I have screwed the adjuster in and out, it doesn't seem to much difference. The air came through no problems. Any idea on where one might start with an initial screw setting?

Thanks,
Al

[Spider]

You'd normally turn the screw right in to get the system bleed but if you are bleeding the system by pumping the fluid through with the brake pedal method, if you are getting up pressure and then opening the rear wheel cylinders, little or no fluid will come out as the valve will be locked off. Use less pressure or open the bleed nipples (one at a time) and run a hose off in to a jar, then pump the pedal down. Lock the nipple again before letting the pedal up again. Repeat both sides until all air is out

[66S]

Thanks Spider,
I reverse bled them for a start but I seemed to be getting some air in through the bleeder thread so finished them as you suggested. The pedal is good now but just wondered what position to set the screw to start with. Any tips there?

Al

[Smiffy]

If your looking to decrease the braking at the rear, you'll need to cut a couple of coils off the spring. Those valves as they come from spares, only allow you to increase the braking effort at the rear.

[WNX700H]

As you screw the adjuster in it will increase the rear line pressure before the valve shuts off , need to play around with wheel cylinder size start with smallest diameter wheel cylinder ( which will give the lowest force for a given line pressure ) you can then increase the pressure in the line by screwing in the adjuster.

Best way to set up the balance on a road / tarmac car is on dry tarmac so you get max weight transferance off the rear axle, with the aim of making sure you get front lock before rears and the vehicle remains stable ..... educated trial and error

[lexie467]

And and if that not helps try this. You need to be two when doing this. One operating the break pedal and the other person the bleeder screw.
As you havee installed a bias unit I presume you know what for! Screw the adjuster left turns till it feels lose. Than turn it right. When you feel it got contact with the spring inside the unit turn another full right turn. Pump slowly up the pressure. Hold the pedal. Open the bleeder. If the pedal not hit floor and you not can see any break fluid poring out just lift the pedal 10mm. Than you will hear a click when the spring releases the valve and just floor the pedal and hold it while locking the bleeder screw. Repeat that till the pedal is perfect.
Now IMPORTANT. The pedal operator must frequently keep the pedal when bleeding to the floor. The other person has to check fluid level in the master cylinder. If that get empty you have to start all over again as you will get air in the system while bleeding it.
To adjust the bias is very easy. If you are a medium strong man, fine. The pedal operator puts the breaks on. Grab the tyre that you have just fitted and ty to turn the wheel. If you can't try again but harder. If you can't turn it screw left 1/4 turn and repeat till you can. Remember you shall only be able to turn it when you rely try hard. And off course vise versa. Than you have to drive the Mini to get it to your perfection. Good Luck.

Tommy

[66S]

Another question please gents. I am finding the wingnut difficult to reach/turn the way I have mounted it. Will the wingsscrew come right out? If so, I can weld a nut to it and turn it more easily with a spanner. I thought it best to ask the question here before I start fiddling with the screw and lose my adjustment which has taken some time to fine tune (nearly there !!).

Regards
Al

[Vegard]

No, it's an Allen headed bolt bolted from the inside with the Wing nut welded on.

I'm normally a fan of mini spares products, but on this item....

http://bit.ly/1fG0fuG

[rich@minispares.com]

No, it's an Allen headed bolt bolted from the inside with the Wing nut welded on.

I'm normally a fan of mini spares products, but on this item....

http://bit.ly/1fG0fuG

you need to be careful buying those wildwood ones as the American ones are not unf, so you have to sort out adaptors etc - I worked on a race car that had one and it weeped fluid all the time, no matter what was done to the threads, the adaptors where just not long enough to accept a unf brake nut.


I would always favour a tilton turn knob type valve - particularly if its inside the car and you want to be able to adjust it.


the modified std ones are only any use if you want to adjust them once every blue moon - the one on my road car had been modified so it has a 3/8th unf bolt so its pretty easy to swing a spanner on it

[WNX700H]

You need to make sure the adjustable valve is a shut off type not a reducing valve. because the Mini has such a short wheelbase the valve needs to be a shut off type ie once you reach the cut off threshold in the valve no more pressure rise will occur in the rear line , only the fronts. The MS vale is a shut off type and you simply adjust the point at which it shuts off by adjusting the wing nut.

Need to play around with wheel cylinder diameter so suggest smallest wheel cylinder diameter with the adjustable valve so can adjust to get ideal utilisation of the rears without rear wheel lock up before the fronts.

The reducer type suitable for RWD or longer wheelbase fwd cars will still allow a pressure rise in the rears depending on what the ratio is in the valve itself , so a 2:1 ratio valve will only allow 0.5 bar rise rate in the rears after valve cut in for every 1 bar increase in the front circuit.

[Vegard]

No, it's an Allen headed bolt bolted from the inside with the Wing nut welded on.

I'm normally a fan of mini spares products, but on this item....

http://bit.ly/1fG0fuG

you need to be careful buying those wildwood ones as the American ones are not unf, so you have to sort out adaptors etc - I worked on a race car that had one and it weeped fluid all the time, no matter what was done to the threads, the adaptors where just not long enough to accept a unf brake nut.


I would always favour a tilton turn knob type valve - particularly if its inside the car and you want to be able to adjust it.


the modified std ones are only any use if you want to adjust them once every blue moon - the one on my road car had been modified so it has a 3/8th unf bolt so its pretty easy to swing a spanner on it

http://bit.ly/1gZmBUw

[66S]

Thanks for your input everyone. I am not quite ready to pull the pin in the MS valve just yet but it is looking like I can't get it adjusted to the absolute point I want. A hex head on the screw would make things a whole lot easier so I hope I can do something while the valve is still connected, save bleeding the brakes again. I like the idea of having a valve beside the driver's chair so that fine adjustments can be made on the run. Hmmmm, will investigate that one and maybe return to the standard bias valve at the rear.

Thanks again
Al

[steady eddie]

Thanks for your input everyone. I am not quite ready to pull the pin in the MS valve just yet but it is looking like I can't get it adjusted to the absolute point I want. A hex head on the screw would make things a whole lot easier so I hope I can do something while the valve is still connected, save bleeding the brakes again. I like the idea of having a valve beside the driver's chair so that fine adjustments can be made on the run. Hmmmm, will investigate that one and maybe return to the standard bias valve at the rear.

Thanks again
Al

Not sure how you are using the car but most regs state the bias valve should not be operable from the driving seat!

Eddie