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Most of this stuff is Viton or silicone from the factory and should last a very long time in service. Barring some kind of fluid contamination, etc. The exception being the CTIS seals which are exposed to potential contamination from the wet tank (fed directly from it). This manifests as gear oil from the hub being present at the CTIS banjo bolt threads on the supply lug stud.
If you are changing entire differentials - first off what is the goal? Are you aware of ECO hubs? If you are considering going from 3.90 to 3.07 you should seriously consider the ECO hubs instead.
Did you get any feedback on the best place to get the seals without them being overpriced?I’m at a similar position, I completely rebuilt the hubs last winter and now have to replace front axle housing outer seals. So this time when I have it apart I’m considering the front axle sleeve bushings, axle U- joints, pinion seal….
I had 3.07s installed by the original shop (bad choice), Not much benefit in driveline speed reduction with 3.07s, which is a big factor in these trucks. However, The ECO hubs Half the driveline speed, putting the engine into the peak torque band for all gears/speeds allowable on US highways (80 across Utah). I'm reinstalling the old 3.90 diffs back in there (with Detroit lockers) now that I have ECO. If you already have 3.90s it's short sighted IMO to not goto ECO unless you're only off roading. The heat and noise reduction is significant. As @GeneralDisorder has stated many times, the extension of life by halving the driveline speed and reducing engine rpm to only peak rpm range is huge. For example, My driveshaft u-joints are shot with only 14k miles with the original gearing. That's 4 items at $125 each. IMO, as a non professional mechanic, running a 6 cylinder diesel at max 2400 rpm sustained, just to do 60-65mph on highway driving is a special category of obtuse. (And 3.07s only give you 71mph at max rpm)We have looked at ECO Hubs - but are not really convinced. Why would that be better than replacing the diffs? Apart from saving time? Am I simply leaving out components?
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Have you read the thread on them?We have looked at ECO Hubs - but are not really convinced. Why would that be better than replacing the diffs? Apart from saving time? Am I simply leaving out components?
Define "overpriced"?Did you get any feedback on the best place to get the seals without them being overpriced?
Have you read the thread on them?
When you say you are "not really convinced" - convinced of what exactly?
What questions and concerns do you still have after reading the entire thread?
FWIW - In my opinion 3.07's and 3.90's with the factory reductions are a waste of time unless you are running a quarry truck or something that NEVER sees over 40 mph (65 kph).
You will destroy the drivetrain 5x to 10x faster with the 2:1 final drives. The military's expected lifespan of these truck is 35,000 miles. And the drivelines still had problems even with that low expectation.
Define "overpriced"?
Big rigs are not cheap to run. Specialized Army big rigs are even more expensive to run. Lots of parts not shared by over the road trucks. Any Meritor/Rockwell/Axle-Tech dealer can order the parts. Being you are in Germany it's difficult to recommend anything that is US based since I don't know if they ship internationally. Many parts for these trucks have export controls also and the manufacturers won't ship them outside the US. Neihoff for example - the charging system manufacturer - requires an EUC to sell military part numbers to the civilian market.
And there is a LOT of parts for which they are effectively NO sources outside the military. For those your only hope is used or surplus which is all in the US.
No and I haven’t had time to dig into it yet.Did you get any feedback on the best place to get the seals without them being overpriced?
It's not so much a matter of speed. You will realize much better fuel economy if you stick to 50 mph. My fuel economy test showed an improvement of 3 mpg at 55 mph with ECO hubs over the original 3.90 differentials.In Germany / Europe we have a maximum speed limit of 50 mph - so changing the maximum speed to 80mph does not bring the success that it does in the USA.
I'm sure Mike could make you a set without the name on them and I suspect that no one would notice or have any idea that you have changed the final drive. These types of modifications aren't considered in the US. There's no one looking at or caring about what final drive a private owner has in their truck. In the US that would be ridiculous besides being unenforceable. There's basically no one in the US vehicle licensing ecosystem that would even know what a hub reduction planetary IS let alone whether or not your imported European truck would or would not be equipped with them. I doubt there's anyone at TÜV that knows either. Don't volunteer any information and if you get questions - proclaim ignorance, promise answers, and find another inspector.In addition, all modifications to the vehicle must be approved by TÜV. If you change a diff now, this is inconspicuous/not visible. When changing to ECO hubs, questions will arise that are difficult or impossible to answer. Or are there official approvals from the truck manufacturers for the ECO hubs?
Even with the reduction from 7.80 to 6.14 your driveline speeds will still be quite high. Concerningly high for the u-joints, and the C6 thrust bearing in the transfer case. Everything in the truck is happier, quieter, and cooler with the ECO hubs. Again - please read through the entire ECO hub thread.As we have already bought the 3.07s, we will now install them. The aim, as I said, is to reduce the revs at 50mpg and still be prepared for rough terrain in Africa (that's where we're heading). In Africa, even 50mph will be very rare - the speed in Europe applies to highways. A maximum speed of 38mph is allowed off these highways. This is where we will be driving most of the time.
Of course we are keeping the ECO hubs in mind - but we are already on the way to 3.07s. Thank you for all the information you share with us.
OK, I´ll read the entire thread and we can talk to each other afterIt's not so much a matter of speed. You will realize much better fuel economy if you stick to 50 mph. My fuel economy test showed an improvement of 3 mpg at 55 mph with ECO hubs over the originaly 3.90 differentials.
I'm sure Mike could make you a set without the name on them and I suspect that no one would notice or have any idea that you have changed the final drive. These types of modifications aren't considered in the US. There's no one looking at or caring about what final drive a private owner has in their truck. In the US that would be ridiculous besides being unenforceable. There's basically no one in the US vehicle licensing ecosystem that would even know what a hub reduction planetary IS let alone whether or not your imported European truck would or would not be equipped with them. I doubt there's anyone at TÜV that knows either. Don't volunteer any information and if you get questions - proclaim ignorance, promise answers, and find another inspector.
Even with the reduction from 7.80 to 6.14 your driveline speeds will still be quite high. Concerningly high for the u-joints, and the C6 thrust bearing in the transfer case. Everything in the truck is happier, quieter, and cooler with the ECO hubs. Again - please read through the entire ECO hub thread.
And with the ECO hubs and 3.90's you would get close to 10 mpg. That's a LOT of money over time. They pay for themselves.After a total of 12 months and 23,000 miles with 3.07 gears, average speed of 50-60 mph, never faster than 60 no matter terrain or road I get a consistent 6.5 mpg.
Well - there are plenty of parts trucks out there and more arriving in the market every day. LOTS of these trucks still going through DLA. Many of them now with the 4x4 high-pinion rear axle which would be a better choice all around even if you stick with the 3.07's because it addresses at least one of the design flaws and allows the u-joints to run inside their design envelope and thus dramatically increase their lifespan.I changed gears almost 7 years ago. Way before eco hubs. If I had a choice today I would probably go eco hubs but I don’t have my old gears to reverse it and install eco hubs.