Can I change diff ratios without any fancy electrical changes ??

blind man

New member
Back in the market for new tyres and due to load rating, I can't get anything bigger to lower the horrendous gearing on my sprinter.
I don't carry much weight and it's mostly highway cruising but at 3500rpm at just 60mph (approx, we run in Klms in oz) it's revving way too hard for my liking and has done for last 3yrs that I've had it but I am sick of it, love the van but sick of the bloody,high revs.:bash:

So, can I swap the differential for a taller geared one as first is next to useless and 5th not long enough....:cry:

Any help on this before I end up selling it as,I can't take it any more.

I asked the local Merc van place,but the mechanic couldn't have given a ****.:thumbdown:

Please help me and my poor van ! :thumbup:

2005 308cdi MWB.
 

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blind man

New member
Remembered that I had asked this before about 3yrs ago...:bash:


I've read the other threads, sent the Italian company an email for a price on gear sets and a few emails to local diff places to see if they can do it and if they've had any drama with ecu's etc, mines a manual so unsure if that changes anything.:rolleyes:
 

lindenengineering

Well-known member
Hey Blind Man
G'day!

I think I need to ask do you know what ratio is in the rear at the moment?
There are some options worldwide but since you are in Auz its a good idea to establish what was put in the van on production and then see if the MB parts support has a taller ratio available right off the shelf.

There's is good reason for this especially if you bought the van second hand and specifically has the ratio been changed before you got it?

Now by giving your last "8" digits of the vin number to the bloke at MB parts counter you should be able to determine what should be the ACTUAL ratio in the van and then ask what taller options are available locally. That is the usual clean hands way of finding out what is in the van.
The other way, (well there several) but the most accurate is to remove the diff pan and count the teeth on both the pinion and crown wheel (ring gear) divide the one figure by the other and you have the ratio. In most instances the crown wheel flank will have some numbers etched onto it which will also confirm the ratio.

For info the other rough way is jack up ONE wheel, mark the tyre at say 12 o clock and get a mate to spin the prop shaft exactly ONE revolution. That will also give you the ratio amount the tyre and wheel rotates. Or do it "vickey verky" and get a mate to count the prop revolutions versus ONE tyre revolution!

The physical change is not difficult for a mechanic to do (if he knows diffs!!) the backlash figures are tighter than American/Asian and even older Brit (Pom) axles. That's because they normally use a different type of gear cutting machinery on production than Euro stuff.
Hope that helps
Cheers Dennis
 

sailquik

Well-known member
How many RPMs are you seeing @ your normal cruising speed? 3500 RPM @ 60 MPH (96.5 KPH) does sound rather odd.
Which engine do you have? 4 cylinder.....5 cylinder OM-647 2.7 liter?
You can probably change the rear differential ratio, but there also will probably be some re-programming of the ECU to adapt to the
new rear ratio.
And, if you are doing this for fuel economy, you could end up with worse fuel economy at the lower RPM.
Do you know what your rear differential ratio is now?
Can you send me a PM with your VIN # and I'll send you back you rear ratio.
Roger
 
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Cole

OUTLAW SPRINTER!!!
I'd be curious on this too.

There would have to be something calculating the transmission output speed vs the wheel speed sensors. Which, I can't see what you would do with that information:idunno:

Which means there shouldn't be anything other than the physical gears that need changed.


I'd like to change mine from 3:73s to a 4:11 or deeper. What were the factory options? Since I run tires 6" taller than stock I've got an effective ratio that is really steep(in the 2s probably) would like to get back to a more stock like ratio. ( but it does put along nicely on the freeway)
 

sailquik

Well-known member
Cole,
The standard ratios in NAS Sprinters (all of them 2002-2014) are:
3.727 :1
3.923 :1
4.182 :1
There are a couple of others that can be special ordered, but none lower than the 3.727 : 1 that I'm aware of.
Roger
 

Cole

OUTLAW SPRINTER!!!
Thanks.

I'd be happy with the 4:18. That would put me most of the way back to stock.

I'm not unhappy with the 3:73 but I know it could be better with just a little more rpm at times.
 

blind man

New member
Had my vin looked at, it seems the ratio is 5.282, that's rediculous as I thought.

Spoke to Stefano from the Italian place that does diff gears etc and it's $490 delivered for new 4.11 set.

I've just fitted 235/75/15 with 116 load index so that's helped a great deal but still needs done , so,I'll get onto it as soon as I've finished house renovations ($35,000 this month :() and a bit skint.

Reckons I won't have to do ecu stuff if it's manual, hope not.

Local gearbox place wants $800 to do the installation, I think that's really too much.
 

lindenengineering

Well-known member
Had my vin looked at, it seems the ratio is 5.282, that's rediculous as I thought.

Spoke to Stefano from the Italian place that does diff gears etc and it's $490 delivered for new 4.11 set.

I've just fitted 235/75/15 with 116 load index so that's helped a great deal but still needs done , so,I'll get onto it as soon as I've finished house renovations ($35,000 this month :() and a bit skint.

Reckons I won't have to do ecu stuff if it's manual, hope not.

Local gearbox place wants $800 to do the installation, I think that's really too much.



Nah mate the time/price quote is about right calling for 6.5 hours minimum labor time.
Lets just hope he doesn't have to spend too much time setting the assembly in the case since its done with selectable shims. Otherwise it will be bloody noisy and you won't like that scudding along to Brissy!:laughing:
All the best to you and have "blind" faith excuse the pun! :laughing:
Dennis
 

blind man

New member
Ah ok, I'll need to just accept that then, want it fixed as it's driving me nuts.


Next thing will be a set of Q7 wheels and tyres so it handles better(steers and turns actually) but they'll need centres bored out.
 

lindenengineering

Well-known member
Ah ok, I'll need to just accept that then, want it fixed as it's driving me nuts.


Next thing will be a set of Q7 wheels and tyres so it handles better(steers and turns actually) but they'll need centres bored out.



Crikey mate!
It will be candidate for the next Cars movie at Radiator Springs with those wheels on it! Maybe even a contender with that high ratio gear set at the Piston Cup races.:thumbup:

http://www.youtube.com/watch?v=_Xbh2ivT0gg

Dennis
 

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