Bedford 466 bus

Hi all, what a champion forum. I have just purchased a 40ft smithfield built 466 bedford motorhome. The bus seems to go okay just a couple of questions, how long do you normally have to wait to build up air for the brakes on startup? The bus has a 5 speed and the gearing between 2nd and 3rd seems a little too far apart, are there any options for fitting a different gearbox? Appreciate any help forthcoming.

Bus-ted, welcome to the forum. The air should normally be up to 60-70 psi in about 30 seconds, with moderate RPM. At that pressure, if an air handbrake is fitted, it should be able to be released.

If the air is very slow to come up, you need to look at compressor replacement or overhaul. Either that, or you have numerous small leaks. Shut the engine off when the pressure is right up, and it should hold with very little drop for a couple of hours at least. If it sinks below 60 psi within 2 hrs, you need to start looking for where the air is going.

A lot of GM gearboxes have poor gear spacings. ACW Bedford are probably your best bet to have a discussion with, over replacement gearboxes. I understand the Commer 6 speed is a favoured replacement, but a good one could be hard to find.

www.acwbedford.com.au/

Cheers - Ron.

Hi Bus-Ted, the air being slow to build up could also be carbon build up in the pipe out of the compressor, or in the non return valve on the wet tank.
Instead of changing the gearbox, have you considered putting a 2 speed diff in.

the governor valve could be crook and the best way to find air leaks is real soapy water in a squirty bottle or some truck wash build up air and go squirting a hand full of small leaks can add up to a large air loss all the best don

Thanks all, the air does seemed to hold okay but i will check it after a few hours. Takes around 7 minutes to build up and the brake warning buzzer??? to go off. How do the two speed diffs work? Cheers.

7 mins is waa-aay too long to build up pressure. You need to give the air system some serious attention. Aussiehooker has brought up an item I forgot to mention .. the air governor.
This device freewheels the compressor when the pressure is right up, and it may be knackered.
They operate on the basis of actuating an unloader port in the compressor, once maximum system pressure is reached. This allows the compressor to just freewheel.
Once pressure falls below about 100 psi, the air governor should close the unloader port.
If the air governor is sticky or worn, it may not be functioning properly and may be keeping the unloader port partly opened.
They are not expensive to purchase, about $25-35 on average. I've bought new ones off eBay for as little as $6.

The suggestion of bigcams to check the outlet port on the pump for carbon buildup is also a wise and simple check.

Replacing an air governor .. www.tpub.com/content/constructiondumptru...-3805-254-34_415.htm

Bus-ted - Two speed diffs contain a planetary gearset in the diff carrier, that is locked or released by a sliding collar dog clutch. Locking the planetary gearset engages the high range .. unlocking it allows the planetary gearset to spin and give you a lower ratio of gearing. This effectively makes a 5 speed transmission into a 10 speed, as you can use the 2 speed diff in every gear. These diff speed changes are usually referred to, as high range and low range.

Eaton put up these videos, especially for you ..

Eaton 2-speed differential operation (part 1) ..

Eaton 2-speed differential operation (part 2) ..

Eaton 2 speed differential design and operation (in print) ..

Page 1 .. www.tpub.com/content/construction/14273/css/14273_190.htm

Page 2 .. www.tpub.com/content/construction/14273/css/14273_191.htm

Cheers - Ron.

being a bedford /english based powered chassis ..the air may take a long time to build up . . my old leyland was the same,when they drained the air tanks at the RTA yearly rego inspections the RTA examiners always joked saying it was going to take a long time to build up pressure . . 7 mins sounds about right . . also starting the motor then going inside to have a cuppa sounds about right ... another option to help your truck along would be to fit a turbo then the gap between the gears wouldnt feel so bad . . having said that what highway speed is the bus capable of at the moment ?

Kenny's right, what sort of compressor is on it? if it's just a little Clayton Dewander single cylinder thing, and it's got a few air tanks it could take a while. The valves in the compressor's make a big difference if they are worn as well, My Reo had no oil in the system, but used to take ages to pump up with a Tu-Flo 400 on it, turned out to be the valves.
Does the air system have any oil in it?

its probably more important that the beddy doesnt have any air leaks.. as it will take a long time to build up . . & of course if your going down a steep grade use your gearbox more than your brakes . . otherways you may not have much air left . . . a bit off topic but a lot of people fit a isuzu diesel . . more power,cheaper on fuel,parts readily avail and the isuzu air compressor works a lot quicker . . my old JCR with the little 6BD1 turbo(5.75litre) litre performs well enough & my tare weight is 8.5 tons . . so its no flyweight . . also the isuzu gearbox the ratios are spaced good