TheSamba.com :: View topic - 69 Bay window front disc brake conversion

Tue Feb 24, 2004 9:18 am

I am looking for info on what year and vehicle I need to get the parts off of to do a front disc brake swap. Do I need the spindles as well? I have looked at kits you can buy but they are so damn expensive. Thanks for your help.

Tue Feb 24, 2004 9:40 am

Start looking at 73-up (71-72 have discs as well but they are smaller so make it worth your while).

You need everything from the steering knuckle outward. Since your front beam has no mounting point for the brake booster you'll be doing without it.

Since all the ball joints are the same I know they will fit in your torsion arms but I don't know how this affects the geometry exactly. If you've got oversized balljoints for some reason then you'll need the torsion arms as well.

Tue Feb 24, 2004 9:51 am

so should I jus get the whole beam with all the parts when I find a donor vehicle? You mentioned a brake booster, how does it get it's power? Thanks for all the help.

Tue Feb 24, 2004 10:15 am

It gets it's power from the engine via vacuum and helps with braking. You need to locate a suitable source of vacuum and run the hoses from back from front if you want a nice pedal feel.

I don't really know what to recommend but having a spare beam isn't a bad idea anyway. Don't forget the brake pressure reducer: it keeps the drums on the rear from locking up as you apply the front discs.

Tue Feb 24, 2004 1:41 pm

mojolounge wrote: so should I jus get the whole beam with all the parts when I find a donor vehicle? You mentioned a brake booster, how does it get it's power? Thanks for all the help.

I recommend the whole beam and the booster. All you have to do is tap a hose off of your intake manifold and wala, power brakes

I did this on my old 70 bus and it was well worth the effort. Everyone thought it was a 71 and I didn't know what I was talking about.

Take the rear suspension from a donor too and convert the rear to match. You will also need the pressure reducer valve. It is a bit of work but you won't regret it when you no longer have to stand on the pedal to stop

Tue Feb 24, 2004 3:27 pm

If you do decide to install disk brakes from the knuckles out ( keeping your old beam) I strongly recommend that you do what is necessary to get a booster bracket welded on. Disk brake pistons have more pressure area than your wheel cylinders, they will be a bear to stomp on without a booster. The booster vacuum line must have a one-way valve to protect the booster from backfires and to maintain vacuum in the event of a stall. The proportioning pressure regulator is designed with the later rear wheel cylinder surface areas as well. Jeremyrockjock is right, do the whole deal and you will have well-engineered braking performance.
Colin

Tue Feb 24, 2004 3:41 pm

booster is not so important. obviously it is better, but i drove many buses with no booster and the braking is not so bad.
here in italy few buses (also later ones) have the booster and people do not tell that it is so bad without.

Tue Feb 24, 2004 3:52 pm

PEPPE wrote: booster is not so important. obviously it is better, but i drove many buses with no booster and the braking is not so bad.

The *drum* brake buses are fine without boosters. I drove a '69 loaded down to the bump stops without a problem without a booster. But the disk brake buses have a quarter of the swept area of shoes, the required pressure to stop a loaded vehicle are waaay higher.
Colin

Tue Feb 24, 2004 4:06 pm

You CAN tell a difference Booster /No booster, could'nt be that much to weld a bracket to hold a booster. I agree go w/ the later model set-up. Y ou can use adapters to keep the wide 5s up front though you kick them out about a 1/2 in. further than the rears.

Tue Feb 24, 2004 4:49 pm

If not having the booster is anything like pressing the brakes with the engine turned off I'll have to write off all those early models that lack one or get those big boots the East German female wrestlers used to have to wear in the old days to stop their cars.

Drum brakes have more surface area but isn't most of it wasted? I mean the brakes make greatest contact by the wheel cylinders only and the shoes tend to wear unevenly as proof.