W124 Diff Ratios??

[ADY1983]

Ok, most of you would have seen my engine swap post, i have been driving the car everyday for work although it is not really finished IMO .
Anyway the old 12Valve diff is still on the car with the 24V engine, apart from the fact the car still doesn't rev past 5000rpm , it seems slow...

Does anyone know the different ratios on the diffs and what effects this would have on the performance of the car?? A mechanic friend of mine who has been helping through the project, has said it wont make any difference, so your on your own to swap them ...

 

[MangoMan]

Hi Ady, all I can tell from looking at the russian site is that they do have different 'Diffs'; the 12v is a 1243502174 and the 24v a 1243508814. And they look quite different aswell. It also looks it's the same for the Saloons aswell. I have to say that my 24v 300 definately feels like it has longer gearing compared to my CE 12v. Which I'm not sure if it is just a feeling but my CE did feel quicker through the gears overall, but I don't know if this would equate to it actually being quicker.

Sorry I can't be of any more help there. Good Luck.

 

[Roger Jones]

Is this what you want?

From the MB tech data handbook -- rear axle assembly, ratio:

Chassis 124.050: 3.07 (four speed box)
Chassis 124.051 (24V): 3.27 (four speed), 3.69 (five speed)

Max revs for M104.980 (24V): 6400 with cat, 6300 without.

And while I'm here:

124.050: 0-100 kph 8.5 sec (auto, cat.), 136.7 mph (220 kph) max. speed
124.051: 0-100 kph 7.8 sec 4-speed, 7.7 sec 5-speed (auto, cat.), 144.1 mph (232 kph) max. speed

 

[ADY1983]

Cheers guys, we know they are definatly different then, anyone know how much a diff will effect acceleration and top end etc.??

I have always planned to swap them but its lack of time at the mo, i would like to do it before the Bridgewood meet...

How long do they usally take to change?

 

[Ian B Walker]

How long do they usually take to change?

About 3 hours if you are lucky. The half shaft to diff bolts can be rather troublesome depending on the bolt configuration. The later bolts are torex while the older ones are 12 point internals. I have found that the Torex ones do cause a problem if you slip, usually ends up having to grind them off.

 

[aka$h]

i would like to do it before the Bridgewood meet...

Im hoping to swap the transmission and diff for the 5sp versions by then. Not sure Ill manage to finish the job tho, might end up bringing the diesel instead

 

[Dieselman]

Given the ratios of 3.07 and 3.27 that's about 7% difference in ratio so accelleration will be slower with the higher ratio diff (3.07).
However it's worth noting that the original ratios might be rather short anyway and the higher ratio will make the gearbox hold the lowe gears for longer which may actually help accelleration.

Until you sort the lack of revs (and presumably power) then there is nothing to compare to.

Interesting that you say your mechanic friend says it won't make any difference, years ago I watched someone upgrade a Ford Escort engine. I said that the caar would be no faster as the gear ratios were the original ones, to which the mechanic replied that it wouldn't make any difference. doh..

 

[Dieselman]

About 3 hours if you are lucky. The half shaft to diff bolts can be rather troublesome depending on the bolt configuration. The later bolts are torex while the older ones are 12 point internals. I have found that the Torex ones do cause a problem if you slip, usually ends up having to grind them off.

Three hours to drop the diff, change the seals and refit.
About an hour to change only.

To avoid rounding off the torx bolts use a short extension on the socket to clear the CV joint. If undoing by hand add a longer extension after the ratchet handle to hold steady with your other hand.
The bolts round off due to the socket not being on square to the bolt head.

 

[ADY1983]

Thanks for all the replys..

Below is some info on the 12v and 24v it might help, i have also used a 12v gearbox so that might have caused a problem too??

These are the two cars from the VIN check...
Couldn't find the diff ratios though...

300 CE
Chassis - 1240502A692035
Engine - 103983 22 107215
Transmission - 722320 03 060428
Order - 0 8 537 23893
Approx. year - 1988
Cab 00097



300 E-24
Chassis - 1240312B742117
Engine - 104980 22 037990
Transmission - 722359 03 697496
Order - 0 2 537 42680
Approx. year - not defined
Cab 00084

 

[aka$h]

Ive just spent some time looking through some .pdf files and the gear ratio's are the same, so the box wont be an issue.
im a little puzzled with the diff ratio's, I dont think it will make much difference because, e320 coupe uses a 3.07 with a 4sp box or a 3.69 with a 5sp (auto).
However the 300ce-24 uses a 3.27 with a 4sp and a 3.69 with a 5sp (auto).
Id have thought if the 5sp box uses the same diff the 4sp would have too.

 

[Dieselman]

Ive just spent some time looking through some .pdf files and the gear ratio's are the same, so the box wont be an issue.
im a little puzzled with the diff ratio's, I dont think it will make much difference because, e320 coupe uses a 3.07 with a 4sp box or a 3.69 with a 5sp (auto).
However the 300ce-24 uses a 3.27 with a 4sp and a 3.69 with a 5sp (auto).
Id have thought if the 5sp box uses the same diff the 4sp would have too.

I think MB selected the different differential ratios to give the same total gear ratios for the 4 speed and five speed.