Top speed calculation

[ratfink56]

Found a Blue Bird 27 pass. CUMMINS 8.3, Allison trans with serial number prefix 6510, 6.14 rear gears and 275/70-22.5 tires. Approx top speed? I found a calculator on line but it asks for the trans final gear ratio.
Allison trans site says it's a B300 but I can find no other info.
Bus is 4.5 hours away from me. As is where is with only an email address.

[Twigg]

Originally Posted by ratfink56

Found a Blue Bird 27 pass. CUMMINS 8.3, Allison trans with serial number prefix 6510, 6.14 rear gears and 275/70-22.5 tires. Approx top speed? I found a calculator on line but it asks for the trans final gear ratio.
Allison trans site says it's a B300 but I can find no other info.
Bus is 4.5 hours away from me. As is where is with only an email address.

The 6.14 is the final drive ratio.

You also need to look up the gear ratios in the transmission, then this is the best calculator I've found:

Gear Ratio Calculator

[ratfink56]

Thanks....

[brokedown]

6.14 is uuuuuuuuuuuuuuuuuuuuuge! If it doesn't have a serious overdrive you'll have bicycle riders honking at you for being too slow!

[Twigg]

Originally Posted by brokedown

6.14 is uuuuuuuuuuuuuuuuuuuuuge! If it doesn't have a serious overdrive you'll have bicycle riders honking at you for being too slow!

It is also an excellent ratio partnered with an MD3060, one I know Thomas and Allison will unlock 6th for.

In a trip bus, with a big engine and MD3060 that ratio is very close to "as good as it gets" with 6th unlocked.

Excellent cruising speed at reasonable revs, and good pulling power from low speeds.

I know this is not what the forum generally expects to hear, because ratios in the 4's are considered best for highway ... but with big tires and a 0.65 overdrive, 6.14 and 5.38 are great FD Ratios.

[Tango]

What RPM does that combo work at on the highway...say at 65?

[Twigg]

Originally Posted by Tango

What RPM does that combo work at on the highway...say at 65?

In my bus ... Cummins 8.3L, MD3060, 11R22.5 and FD 5.38

2000 rpm would be 65 mph in 6th gear

With 6.14 FD, 2000 rpm would be 61 mph and 2200 would be 67 mph

I can liberate more rpm from mine if I want to. Valve springs are good to 3400 rpm ... Currently it's governed to 2200 rpm, and simply shimming the springs would probably get another 400 rpm if I felt I needed it. I don't need it unless Thomas refuse to unlock the MD3060

[brokedown]

With that 6th gear it should be pretty good indeed, that 0.65 is a very nice overdrive!

[EastCoastCB]

Originally Posted by brokedown

With that 6th gear it should be pretty good indeed, that 0.65 is a very nice overdrive!

Chris' allison 1000 has a .61 6th gear!

[ratfink56]

Thank you all for the input. The bus is on ebay and located in Stillwater OK. As is, where is. The email link does not work. No way to contact anyone. No info as to whether it runs and/or drives. A real pig in a poke. Too far for me to go look. Anyone interested have at it.

[ratfink56]

OK finally got a reply from the city of Stillwater about this bus.

"
New message from: city-of-stillwater-ok (365)

Yes, a clear title. I started it and let it run for awhile just last week. It has keys but only for the doors since the bus doesn't actually have an ignition key."

Two days left on the auction with no bids. 2003 Blue Bird bus. EBAY