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single axle with lift axle in front or rear

kevin, i've been listening to your show & recently u talked about a single axle with a tag aka life axle in front or the rear. i'm wondering where would be best to put the lift axle, in the front or the rear? 2nd i'm curious as to on snow/ice how will this affect the driving on snow or ice with chains if needed?

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I switched to single drive with a tag about year ago it does affect your winter driving. I run the northwest most of the time loaded most of time at 78,000 plus I am running a locker rearend on the front as the drive axle and I did have more trouble than I did with the twin screw. If I hadn't been able to dump the air on the tag and lock in the locker I'd would have had to chain probably 70% more than I did with the twin screw in the winter. And that doesn't even consider the excessive tear wear on the drive axle only.

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ok i understand what ur saying & appreciate it; but how much extra wear does it put on the drive axle alone? which tires would be best for this combination, super singles or duals?

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brandnewma I tried the Super Singles twice now depending on much weight you run might make a difference. I am always 78,000 plus and run a lot mountains. Super Singles X One XDA Energy I got 53,000 miles out of a set. Right now I went to Duals to try and it looks like I am ending up with about 90,000 miles out of XZA 3 plus. I will be trying a different brand of tire real soon to see if they'll do any better. On the tag axle those tires might dry rot before they wear out. They were on the trailer for about 60,000 miles at first then I moved them up to tag axle when I installed the tag axle have 200,000 miles on them now and out of 13/32 tread they'll still have 7/32 left. Anything else let me know.

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53,000 out of super singles? i'm getting almost 275,000 now out of duals on this truck i have now. something is wrong

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No there's nothing wrong alignment is perfect tires wear nice and even. That's why I said The weight and mountains are big factor your putting all the torque and horsepower to 1 axle instead of 2 and I run 1275 miles each direction and out of that 1275 miles there's probably 25 to 30 percent of it climbing hills and 50 percent of it 2 lane highway thru some towns. I've talked to other drivers that's done the single drive with tag axle and same type of operation and 90,000 miles out of set of duals is typical.

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ok, what about on normal terrain?

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That I couldn't say but you aren't going to get that kind of mileage out those tires running a single drive with a tag axle that your getting now that's for sure.

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almost seems like i'm better off just sticking with dual rear ends & maybe going with super singles

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I converted to a single rear axle with a forward liftable axle two years ago and I love it. My advice would be to leave your rear axle and remove the forward drive axle and replace with a liftable axle. It cost a little more to do it this way, however this is the better option. You need to have an equalizing valve installed that keeps equal pressure between your drive axle and your lift axle. I use a Williams equalizing valve. Some people do not install this valve and just have a constant setting on their lift axle. With a constant pressure setting the lift axle will at times actually pick up much more weight than the drive axle which leads to spinning out or loss of traction. The equalizing valve adjusts momentarily on the fly so your weight distribution is always equal at all times.

I run northeast, tankers and van trailer. With tankers I'm 80,000 one way and empty the other. With van trailer I'm around 75,000 almost all the time. I converted to super singles, (Michelin XDA energy for the drive axle and Michelin XTA for the lift axle) and on my first set I got 110,000 out of the drives and it looks like I'm going to get just over 300,000 out of the lift axle if the wear stays true. I drive on snow and ice quite a bit and really don't have much trouble. Sometimes if I get into deep snow, like in a parking lot, I will spin out or loose traction and I usually just hit the button for the lift axle and that drops all the weight on the drive. Usually that will get you going enough to start moving again then I return the lift axle to the downward position. I don't have a full locker in my rear axle and I've got along without it for the last two winters. If you can install a full locker I would recommend it, you will double your traction in a slippery situation. I believe that a good conversion, (meaning rear drive axle with full locker, forward liftable axle, and equalizing valve) is actually a much better setup than duel axle with power divider. Hope this helps.

Update

Yes, I've heard of that. On our conversions the only way to adjust weight is on the valve itself, which is located outside the cab between the frame rails, usually mounted on a cross member. There is a screw on the bottom that can be turned in or out to adjust weight difference between the two axles. Although it may be better to have more weight on the drive, I agree that probably your best bet is to keep it equal.

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What r the pros and cons of forward lift or rear lift axle?

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My dad just bought a 2014 T660 last fall with the rear tag single drive option(the one from Dana with convertible rear axle housing that allows a relatively easy conversion back to 6x4).

He hates it.

He has had traction issues everywhere. I've told him that KW must have something set up wrong with the leveling valve because he has even spun out backing into a dock at our perfectly flat terminal, on nothing more than a wet pavement(NO ICE), with about 30,000 in the box. That just can't be right, the rear axle is doing far too much lifting IMO. If KW can't get it straightened out for him soon he will be converting it to a 6x4 (at a big loss).

I plan to try the single drive with a front liftable on my next truck, but the rear tag idea seems awful sketchy to me.

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I agree with Rick Williams 100%.I also did the conversion on my 99 volvo with the williams valve. Im getting about the same mileage on tire wear as Rick is.I love this setup i pull a tank so im empty 50%,it works great.With the forward lift axle you need the proportion valve because the air bags on the lift axle have more air pressure in them but have less weight on them,The bags are closer to the axle than my volvo bags,so if it had the same pressure the lift would have alot less weight on it.When the system was new I axled it out many times and adjusted the lift so it has about 1000 pounds less than the drive when loaded.I think that helps traction a lot.Mel I think part of your tire wear is equal weight on both axles and mountains,its probably spinning a little going up hill.I also have all the Pittsburgh Power add ons, so im able to put big power on my single open and micro blued rear.So far its holding up great,2.5 years now.In my set up I gained on fuel mileage also i lost 600 pounds on the conversion. i went with the Rowe truck setup,they are great to people to work with.I also think i have better traction empty in snow because the single axle weighs 13 or 14000 empty so more weight than a twin screw.

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Rick out where I run your setup would be illegal because CA requires that you plumb your tag into the same load leveling valve as the drive axle so that the weight on the 2 axles are about same weight and there is a few other states that split the weight on your tandems as well and there can't be that kinda difference in weight. Since this post I went back to a tandem drive axle and I prefer this setup much better than the single drive axle.

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I'm not sure if your talking to me or Rick Goodman. I also had Rowe truck equipment convert my truck. I can tell you that it is legal. The tag is plumbed into the same load leveling valve as the drive axle. There is also an equalizing valve plumbed between the two axles to keep exact same weights between the tag and drive axle. Some people do the conversion and do not install this extra equalizing valve, this is where you run into trouble. Imagine a speed bump on the road. Your tag axle rolls up on the speed bump. If you don't have the equalizing valve it will lift your drive right off the ground and you loose traction. The leveling valve is slower to adjust but the equalizing valve adjust in a split second. There is an adjustment on the equalizing valve where you can put more weight on the drives and less on the tag. I have mine adjusted so it's equal but it does better if you leave a little more on the drive. If you are running in a state that requires equal weights then you just have to set it up so its equal. For me I don't base anything on CA. I don't agree with their policies and I won't go there. I'm doing just fine without CA. I also realize that this isn't an option for everyone. What is the allowable difference between the two axles in CA? I'm usually within a couple hundred pounds. I used to spin out way more with a twin screw than I ever do with my new setup. If people are having traction and spin out problems with this conversion they have done the conversion wrong.

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CA is not the only state. Mi gave me a ticket for 800 lbs difference on a tandem and I know WA gave my dad a ticket for having a way of adjusting the air in the suspension from the cab of the truck is has to be outside of the cab

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What did you guys see as far as a fuel mileage gain by converting to a single drive axle? If your wearing out tires in the 100,000 mile range you would have to gain a minimum of 2 tenths just to break even. I have a new glider on order with fitzgeralds and its speced as a 6x2 but I might reconsider after reading all these reports. My Xone Xda energy's lasted around 250,000 on a 6x4. I just put the new Xone Line Energys on a few months ago and they are supposed to last much longer. This all comes down to a cost benefit stand point.

Update

http://nacfe.org/wp-content/uploads/2010...

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I gained 6 tenths off the conversion. It cost around $6,000 for the conversion. My last drives lasted 110,000 miles however my lift axle is going to get over 300,000. When you average these two it is 205,000 miles. That's close to your 250k. I would only recommend this conversion after you have already done everything else to improve fuel mileage. I'm happy with mine and it works for me.

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I am specing out a new truck for Canada, will be going from Vancouver, BC to Winnipeg, MB. About 600 miles of mountains one way.Just spoke to people at Meritor, they said one diff can't handle 90,000 lbs????!!!! And I see so many people here pulling 80k+ with one. I am looking at ordering a Volvo 670 (high rise cab) with D13 and IShift (AMT). Would you recommend a different setup? and why? What other fuel saving options can I get?

All input is appreciated.

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