Power Assist or Not

[Steven N]

I am at the crossroads of which way to go. I think back about no assist days and my leg is starting to bother me already.My car would be used almost exclusivly for pleasure driving very little chance of racing.Has anybody had the chance to experience both and relate such ?

 

Steven,

I had twin boosters in mine, I converted to no-assist.

If you really are a pleaseure driver, go for assist.
We in Europe use a lot single booster from Austin (GB). It is a lockheed unit. However you need 2 of these.

It all depends what (donor) brakes you have.
Also, you need to make sure you have enough vacuum, but I guess for pleasure driving your engine will generate enough.


Jukka

 

[Frank Catt]

The braking system on any vehicle must be considered as a whole, not as individual parts, to determine your needs. Start at the brake pedals,determine how much force you are putting to the master cylinder (pedal ratio,most systems have about 6-1), then the size (bore)of the master cylinders and the displacement needed to operate the calliper pistons. Consider whether the force required to operate the brakes needs additional assistance, most well designed systems should not need any! Secondly, if you are using multiple carbs or individual cylinder intakes (such as webers etc.)it is unlikely that you will get sufficient vacuum to operate two servos(boosters). Dont just fit boosters and hope its right,work it out first, its not that difficult.

 

[Guest]

Hello Frank,
your message is taken on board suffice it to say, I run Kinsler injection bodies (8*62mm) and take the vacuum tapping from the rear most body. No resevoir tank and the brakes work fine with twin servo's. I am looking to put a third servo to operate the clutch being an 'old man', my wooden leg is giving me problems. The brakes work just fine as demonstrated by Julian at Goodwood when he 'cooked' the fronts in 3 laps!

regards
Roy Smart

 

[Frank Catt]

Dear Roy, I accept that when you 75+ years old and driving a GTD40 with a wooden leg you need srevos, I have also in the past fitted servo (boost) to aid clutch operation, of course you still need one for the throttle to keep up with paul!. As Malcolm was saying in an earlier posting, too much boost for cars used for track work is not good,even dangerous, and I still believe that systems should be thought out thoroughly rather than be put together with unrelated bits. You experienced how heavy I brake (at Spa)but I would not like any system that would allow me to lock brakes,even in an emergency. By the way, your car is now in the paint shop. Frank

 

[Guest]

Frank, you surprise me! I thought you would appreciate that being able to lock brakes as a drivers option is actually a good thing for a car. If you can't lock the brakes then you are not getting the best possible braking. It is up to the driver to not lock them and feel the best braking friction between tyres and road surface possible. Also if you spin a car you may want to lock your tyres so your trajectory is a bit starighter than with unlocked wheels. A trick I use perhaps a bit too often!

On servos I think it a personal choice and depends on the rest of the set up ie pedal box and brake component sizes etc. There is a slight difference in feel that some people like and some don't.

I run servos and haven't found them hampering my braking performance or times yet!

Malcolm

 

[Frank Catt]

Malcolm, its a personal thing!I just do not like a car that readily locks brakes, because in an emergency, when panic sets in,thats just what happens, and then it all gets a whole lot worse. Frank