Mercedes AL3 and HL7 available axle ratios..

[Sitec]

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.

 

[VerMonsterRV]

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.

 

[Neil]

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

This could be worth exploring

Neil

 

[charlieaarons]

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.

 

[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

 

[Sitec]

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...

 

[Cois]

Good day Sitec. Just wandering if you resolved your ratio issue.

I have recently purchased a 1999 Econoliner 1617 4x4 (OM366A). The diff rations is 48:7 (6.86) which is really low in my opinion. I managed to source available ring/pin parts:

If I have my calcs correct, at the 3.917 ratio, this will place me in the 1600 - 2000rpm range at speeds of 80 - 100km/h. My truck has the 5-speed G3/60 gearbox (not sure about the ratio's - please share if you know) and the transfer box I have no idea about.

So I'm wondering if you did die axle upgrade or the gearbox upgrade?

 

[Sitec]

Good day Sitec. Just wandering if you resolved your ratio issue.

I have recently purchased a 1999 Econoliner 1617 4x4 (OM366A). The diff rations is 48:7 (6.86) which is really low in my opinion. I managed to source available ring/pin parts:
View attachment 669984
If I have my calcs correct, at the 3.917 ratio, this will place me in the 1600 - 2000rpm range at speeds of 80 - 100km/h. My truck has the 5-speed G3/60 gearbox (not sure about the ratio's - please share if you know) and the transfer box I have no idea about.

So I'm wondering if you did die axle upgrade or the gearbox upgrade?

Hello Cois.

I have not done any more on finding higher ratios. I thought I'd get the build finished, and then once we have taken a few trips, then look to power and diff upgrades if needed. A few have said that most of the time they are only cruising around at around 90kmh so don't need to go fast... Watch this space!