Bedford diff gears

Yes my calculations worked out to be very close to that there is 2 1/2 tonne of trailer and burnout car with tyres behind the bus i have hit 80kms a few times without the trailer but i will check the speedo with the gps thankyou for your help

"Yes its doing 2700 rpm just off the rev limiter"

That's a lot of noise next to your knee.

I think everything is as good as you are going to get. We are talking 50 year old machinery here.

During my brief interstate career my brand new Perkins Commer was among the faster trucks on the road competing as it was with English machinery, B Model Macks and 1418 Mercedes. With an average of 45mph and single axle trailer I was the passer not the passee. Only the few new Kenworths, overnighters and petrol Dodges were consistently passing me. Except for downhill runs I seldom saw 50mph(80kmh) on the speedo. It ran effortlessly at 2,600-2,800 rpm with 5 speed direct drive gearbox and split changing the two speed axle kept her singing perfectly in the sweet spot..

I don't think you are going to do much better from your posts. You have the oversize tyres which look to be as much as the old girl can handle with up-gearing. Messing with diffs and overdrives is only going to over-gear the Perkins and you will find the only time you can pull top gear is going downhill. You also only have 50mph suspension, steering and brakes so any major diff/gearbox/engine upgrade is feeding strawberries to pigs.

Seeing 80 kmh occasionally on the speedo as you have mentioned says to me that the drivers back in the day would be jostling to take the "nippy" Bedford leaving the Leyland turtle to someone else to drive for the day.

Lang

300 diesel, standard five speed and single speed rear axle - 80 kph flat strap, up hill and down hill almost . . . did see it manage the odd kilometre or two with a following wind. :lol:

Comfortable old bugga with the Mercedes buckets I put in there, but I wanted a wee bit more speed at that time in my life (note the hair was not white then). Damn, why am I working on my O Type now!?

You can overgear a bit with a two speed diff,without losing 10-15mph as happens when you are hit with a slight slope or a bit of headwind and have to change down a gear........With the same ratio ,a 2 speed diff makes a huge difference in point to point times anywhere a bit hilly.

11r22.5 (tubeless) is equivalent radius to 10.00 radial.
Those older 6BD1 and 6BG1 Isuzu motors were a popular conversion but may be getting rarer now. I think they revved to 3,000rpm so same gear ratios could be used. The last of the Isuzu non electronic engines is 6HE1 but they only go to 2,700
Could maybe wack in a Bedford 500/

You can overgear a bit with a two speed diff,

If looking at the 2 speed diff, just check the mounting point positions. The bus and truck chassis are different widths and the 2 speed usually doesn't fit.

Could maybe wack in a Bedford 500/

He wants to go faster!

JonD is right ...the bus axle is several inches wider than the truck axle.(maybe 4?)

Yes have found that to be the case i have found a solution fitting a 302 Cleveland v8 and let it rev to 3200 rpm at 100kms

Well there goes any planned retirement fund just keeping the fuel up to it :whistle: :whistle:

Depending on what you plan on doing is were I would start if it was mine

If I had the rest of my life to get there and enjoy the world rolling on by I would leave it as is, I dont think thats you're plan other wise you wouldn't be asking

If you want to get there today and just start and run and be able to afford the fuel bill, your V8 petrol wont be a option

I think you will be surprised just how gutless the 302 Cleveland is going to be for this type of work, I doubt it will even go as good as the Perkins despite what people say

So your options are closing in pretty quick,a Perkins Phaser that are nearly twice the power you have now or a 5.9 Cummins are probably the go and good overdrive box behind them, I think the best over drives, as in ratio are Allison, 0.6 -1
Leave the diff as is and I feel you will get the best of both worlds, drive ability and economy

Just some thoughts, I do have friends that fitted hotted up 351 Clevelands to a bus for going to drag strips interstate back in the late 80's and they were very dissapointed, they fitted Isuzu motors and a few other things to get the performance they were chasing

Im the dim dark recesses of my brain I feel many years ago on here someone went down this very path and found the same results as well

Swishman might remember who it was

Paul