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braking and master cylinders?
omega0684 - 23/2/06 at 10:03 PM

hi everybody, got a question about braking, why do some cars have single master cylinders and others have twin master cylinders( i assume one is for front and the other for rear) why is this beneficial to the braking of the car, can someone please explain this for me.

thanks Alex

tasmin289 - 23/2/06 at 10:14 PM

A twin master cylinder is effectively two independent braking systems built in one housing; so if you lose one circuit you still have braking to two wheels. With single line master cylinder, losing a circuit means no brakes at all.

omega0684 - 23/2/06 at 10:17 PM

r both master cylinders connected to the brake peddle then

Jon Ison - 23/2/06 at 10:19 PM

yup, in a lot of cases by a "bias bar" this way you can adjust the amount of braking too the front and rear independently.

flak monkey - 23/2/06 at 10:20 PM

With twin master cylinders you can adjust the bias from front to rear without too much hassle. You have one cylinder for the front the front and one for the rear.

If you have a single master cylinder you cant adjust the bias so easily. Just because you have one doesnt mean you lose breaking if it dies though.

Common mistake, tandem master cylinder is one unit with two different outputs (one front one rear or diagonal split). Twin master cylinders are two seperate units, one front, one rear and need a balance bar setup to work.

David

tasmin289 - 23/2/06 at 10:21 PM

Hi my post was slightly misleading. You mean 2 brake master cylinders side by side? If so; yes they are both connected to the pedal with a balance bar.

skydivepaul - 23/2/06 at 11:57 PM

quote:
Originally posted by tasmin289
Hi my post was slightly misleading. You mean 2 brake master cylinders side by side? If so; yes they are both connected to the pedal with a balance bar.


Yes thats right. Normally that sort of set up is reserved for racing use and the balance bar control is mounted in the cockpit for easy adjustment whilst driving. It is not needed for road use or even track day use unless you have the budget or inclination to have this sort of set up.

JAG - 24/2/06 at 09:12 AM

quote:

It is not needed for road use


To clarify - any vehicle with a driver adjustable brake bias system is actually illegal on British roads.

For SVA the balance/bias bar has to be locked and non-adjustable.

That's not to say some people don't change that after the SVA test.

omega0684 - 24/2/06 at 09:49 AM

yes i was reading the DAX build manual last night, and they say that you need to have a small spot weld to hold the bias bar in place for SVA.

one problem....i dont have a welder

Alex

JAG - 24/2/06 at 11:23 AM

Some people drill through one m/cyl' fixing and the adjuster rod and insert a roll pin. That does a similar job.

Mix - 24/2/06 at 11:41 AM

I wouldn't advocate drilling through the adjuster rod and push rod clevis, this will weaken the rod greatly in an area that experiences load under braking, far better to add a lock nut to each end of the adjuster and drill through these and the bar. This area of the bar experiences no load under braking.

Mick