Mercedes AL3 and HL7 available axle ratios..


Hi all. Anyone have any Mercedes contacts? I'm chasing info on what axle ratio's are available for the axles under our Mercedes 1222a. I have an AL3 front axle (current ratio 1= 4,300 as stamped on plate)), and a HL7 rear hub reduction axle (current ratio 000=4,333). The gearbox is a 6 speed G4/95 - 6/9,0 direct drive 1:1 in 6th, and the truck is sat on 315/80 R22.5's. With the V6 engine just off the red line at 2100 RPM, I have a top speed of 95kmh. I'm looking for another 10-15 kmh... I can get a 3.7 ratio for the rear HL7 I believe, but not sure on the front...

Any suggestions? Cheers in advance.


Gotta Be Nuts
A while back I contacted Atkinson Vos about their "speed upgrade" for our trucks (the example truck is a 1617). They got back to me and they were able to source new ring/pinion for the front and rear axles on our truck. Parts alone were going to run about 5k pounds and we were only going to gain a few MPH top speed. I decided to hold off and see how we felt. On a slightly different track (but still on the idea of higher top speed), there is a guy in Germany that is adapting a Mercedes transmission off one of the 2WD highway trucks (same guy that we are getting the upgraded Atego turbo from). These transmissions had an over drive and 6 speeds. Now his conversion is for an LN2/OM366 so it would be different than yours but I wonder if there was a 2WD highway version of your truck/engine combo that would have an overdrive? I know I am watching what he is doing very closely, though I think it will end up being more work than I am ready to tackle.


Many years ago I read of folks shoe morning a Claas overdrive unit into Unimogs on the OM352a engine.

This could be worth exploring


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Won’t work; specifically designed for Unimog which has transmission divorced from clutch housing with driveshaft connection. And the OM501 has at least double the torque of OM352.
Think about ZF 9 spd with 0.75 9th and 9.48 1st. You will maintain low 1st gear but rpms in top gear will decrease 25% at same speed.
MB doesn’t make overdrive 9 speed.
Or even MB 12 or 16 speed.
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nick disjunkt

The G85-6 on the later Atego 18 tonners has a 0.7 overdrive in 6th gear. With a divorced transfer case I can't see it being a huge job to swap over to the newer gearbox provided the bellhousing is the same pattern. The hydraulic shifter mechanism on the G85-6 should give some flexibility with the positioning of the gearstick. They are very common in Europe, but I've no idea if they were used on Aus merc trucks


Thanks Nick. Thant's good info! Funnily enough I looked at one on a pallet the other day... The price tag of $8000 the fella threw at me put me off a bit, but at least I now have some options... I've also since found out that the 4x4 Atego 1629 runs an AL3 front axle with a 3.909 ratio... If I can get this ratio in the HL7, then I'm on to something... :)