Mercedes-Benz

[BearZahn]

Hi all. Eric here from oz looking to see if i can get some advice reguarding a Mercedes-Benz 1981 03/05 school Bus only doing 75kmh on highway.

Eric

[G-CPTN]

1st ratio: 2.12:1, road speed: 35 km/h
2nd ratio: 1.35:1, road speed: 55 km/h
3rd ratio: 1:1, road speed: 75 km/h

http://en.wikipedia.org/wiki/Mercedes-Benz_O305

[BearZahn]

Thankyou for that.
The problum is i cant find out any info as to what has to be done to bring the road speed up to 100kph for highwas use I belive I have to get the diff ratio changed however I cant find anybody that has the knowledge to advise me as to parts and locations


Eric

[G-CPTN]

75 to 100 is a big jump.

You would need a different final-drive ratio of 4.4 instead of 5.9 if there ever was one available!
I see that Perth had O305 vehicles with 5.2 final drive but that would only increase top speed to 85 km/h.
This is a rear-engined vehicle, and I don't know the whether the transmission was integral or whether it utilised a prop-shaft to a 'standard' rear axle.

You might be lucky if MB built a similar layout vehicle for coach use (though this might have been achieved by an overdrive ratio in the main gearbox).

You would need an overdrive ratio of 0.75 to achieve 100 km/h.

Adelaide O-Bahn buses to were specially modified Mercedes-Benz O305 models. A fleet of 41 rigid and 51 articulated buses was purchased.
The chassis were bought from Germany and heavily modified at the Mitsubishi Motors plant in Tonsley.
The rigid buses had their power increased to 240 hp (177 kW) and the articulateds to 280 hp (207 kW); they were the first buses to travel at a speed of 100 km/h on suburban routes.

So you need to find someone involved with the Adelaide O305s and find out how they achieved the increase in road-speed.

You might also want to investigate the MB O307 suburban model (which might have had a higher top-speed) or the MB O407 (which had multi-ratio five and six-speed transmissions).

[BearZahn]

Top reply the infomation you have given me is just what ive been looking for. Now I have somewhere to head and can start doing some ringing around.
Once again thank you for your detailed information it helps me greatly.

Eric