Diff Change

[Kappy]

This may seem a little premature only having purchased my rig the other day and still haven'y taken possession.

But just curious I believe my rig has as the current owner puts it a "slow diff", even though it didn't feel that way on the freeway.

However should i wish to change to a highway diff, can members advise me how difficult a process it may be.

Rig is a 91 Mercedes Ex school bus,OH 1418 single axle, with a Volgren body. i was sitting on by the speedo at around 95-97 km/h and felt there was more.

Anyway just curious.

Thanks in advance.

Cheers
Kappy

[T1 Terry]

The taller the diff ratio, the further the gaps between the gears, so keep the ratio as low as practical. There really isn't a fuel saving above a certain point, if you already back off before the engine reaches the governors then I doubt a taller diff would help much, but if it's screaming for mercy and you still think you could walk faster then a diff change could be a serious consideration.

[BruceS]

If it was going over 56mph then it does have the highway diff already.
I'm not familiar with that bus set up but from memory it is rear engine. Does it have any tailshaft at all or is it 'close-coupled'?
I totally agree with Terry on this one. A lot of bus conversions are happy to sit on a steady speed like 85-90. Less rattles, broken plates & testicles tangled around kidneys!!!

[mikeg]

Kappy, is it front, mid or rear engined?

[Dot]

So does that mean our bus has a highway diff because I haven't felt my testicles anywhere near the kidneys

[Wilbor]

You're not feeling them properly then Dot, you need more practice

[Kappy]

Thanks guys for the input.

Rear engine and I haven't had real close look at the coupling, every thing just looked clean underneath.

As I said the speedo show 97 and about 2100rpm, but the owner said his GPS was 90, anyway all was smooth and cruisy so maybe 90 is cool.

I get the mobile home mindset is different to petrol head mindset,I'm sure I'll adapt.

Probably just fishen when I get her home I'll have a good look. Just a tad impatient and excited. lol

Cheers
Kappy

[supersparky]

You will know whether it needs a bigger diff or not by the time you drive it home. That is, assuming you will be doing some highway miles. After about 85kmh all you are achieving is excessive fuel consumption.
And you are right, it does take a while to de-petrol head yourself.

[Kappy]

Yes the run home is about 200 odd k's of highway running with up hill and down dale and flat bits.

I have already found it moves nicely through the gears.

For the petrol head boost I'll run the Hog.

Cheers

[jon_d]

2100 at 90 is a good place.... good torque, probably the best for fuel consumption. 100 will be about 2500