I guess only wayne can get by with that line, eh?
Why do we have brake pressure regulators?
Is it because our brakes are disc up front and drum in the rear and they (disc vs drum) require a different pressure "signature"?
Or is a weight issue where most of the weight is in the rear of the bus (or truck or whatever) and we do not want the lighter rear to "lock up" when there is no weight back there?
Or is because the front brakes do most of the braking and we want to send more fluid pressure there for that reason? Possibly a "power brake thing?
Did cars with 4 wheel drum brakes use them? Cars with 4 wheel disc brakes use them? My first one that I can recall was my 71 Datsun PL-521 pick up (disc/drum) and my 77 Jeep J-20 Pick up (disc/drum)
I cannot remember if my splitties or non-fat beetles had them. I had a 72 gia and I never looked to see if it had a brake pressure regulator.
Just wondering.
Randy in Maine
Brake pressure regulator - Wayne's question of the week
- Randy in Maine
- IAC Addict!
- Location: Old Orchard Beach, Maine
- Status: Offline
- Amskeptic
- IAC "Help Desk"
- Status: Offline
Re: wayne's question of the week
The fluid pressure dynamics favor drum brakes. Drum brakes have this great leverage between the anchor and the wheel cylinder that disk pads do not. Because disk circuit pressures have to be higher and use more volume than drums, the master cylinder is more likely to lock up the rears on disk/drum than drum/drum. VW's lovely little system turned out to be elegant and extremely adaptable to the bus chassis because the VW bus has probably the greatest pitch under braking of any vehicle ever sold. The inertia style regulator is right at home in a bus when that chassis does the nose-drop, and it works extremely well on steep downhills too even when you are not braking like a maniac. Most every disk/drum set-up requires a regulator to synchronize brake application between the disk circuit and the drum circuit.Randy in Maine wrote: I guess only wayne can get by with that line, eh?
Why do we have brake pressure regulators?
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
- covelo
- Old School!
- Location: Fairfax, CA
- Status: Offline
Don't try the reverse: backing down a steep dirt track with bad traction. You touch the brake, the front locks up, and no steering. This is how we ended up having to be towed by a Nissan pickup in Covelo one rainy spring day.
‘80 Vanagon Westfalia - 54,400 miles
'91 Toyota Pickup (4WD long bed) - 199,960 miles
1987 Alfa Spider Veloce - 166,400 miles
2017 VW E-Golf - 5,600 miles
'91 Toyota Pickup (4WD long bed) - 199,960 miles
1987 Alfa Spider Veloce - 166,400 miles
2017 VW E-Golf - 5,600 miles
- Amskeptic
- IAC "Help Desk"
- Status: Offline
You are so correct, covelo. But you try to save yer ass in that circumstance by very aggressive stab-n-steer cadence braking. That is where you hit the brakes hard so the rears can slow you down, release to steer, hit the brakes hard, release to steer, hit the brakes hard, etc.covelo wrote:Don't try the reverse: backing down a steep dirt track with bad traction. You touch the brake, the front locks up, and no steering. This is how we ended up having to be towed by a Nissan pickup in Covelo one rainy spring day.
Try to avoid it though.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
- Gypsie
- rusty aircooled mekanich
- Location: Treadin' Lightly under the Clear Blue!
- Status: Offline
- Amskeptic
- IAC "Help Desk"
- Status: Offline
An excellent suggestion. Automatic transmission buses can stay in forward low while backing down also (see PV4 mag 1972-3 bus at Saddleback Hill)Gypsie wrote:Just wondering if a bit of parking brake would help balance the braking load in this backing down situation? I have used this method and wonder if there is any reason that I should not. I use this method for uphill starts as well.
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles