Single Screw Rear End

[WIMFClay]

Good afternoon folks, first time posting here.

After reading through some posts about fuel economy, I would like opinions/ experience from others on a related subject.

To preface this, I mainly haul grain to the same end user about 155 miles each way. 153 of those miles are highway/interstate. Always bounce back empty. Do not haul anything out during the winter months the trucks stay parked.

Who here has a single screw with a lift axle in front to make it tandem when loaded? My dad had always wanted to try one but they are quite rare and as far as I last knew they aren't even offered from paccar. That being said I would not mind converting an existing tandem axle tractor into a single drive axle with a lift axle in the front. I believe everyone uses 46k rear for the extra durability.

My questions are:
Is it worth the work?
What is the max hp/tq for a single axle and is the diff the weak link or lack of traction?
Is it noticeable power increase?
What kind of fuel savings could someone expect from less friction of only one differential and two less tires on the ground when empty (assuming super singles)
How much does it affect the light weight?
What lift axle did you go with and rough cost?

I am not concerned about traction whatsoever because we do not haul during the winter and 90% of the miles are the same exact trip. I am interested to hear from people that have experience building/driving a setup like this. I do think it would be "cool" to bounce back on 6 tires instead of 8 (lift axle on trailer). Plus being a day cab I would think the ride quality may improve by lengthening the wheel base when empty.

[hookliftpete]

I run a single axle pete straight truck with a lift, it definitely makes a difference to not have a full tandem as far as fuel goes, however, it puts more strain on the axle shafts, as all the torque is on one wheel set rather than 2, have broken two axle shafts when pulling out heavy, not sure if this may be an issue for you.

[Rawze]

Better fuel economy when loaded light ... but quite a bit more tire wear on the back axle due to the drop axle not providing power to the road. - Most people I have spoken to say that Its a trade-off. Typically, the fuel efficiency gains are not that good after having to replace back tires more than 2x as often = are not enough long term savings to justify converting one over, nor hardly pays for the faster wearing tires most of the time.

just my thoughts any ways.

[WIMFClay]

(05-02-2026 )Rawze Wrote:  Better fuel economy when loaded light ... but quite a bit more tire wear on the back axle due to the drop axle not providing power to the road. - Most people I have spoken to say that Its a trade-off. Typically, the fuel efficiency gains are not that good after having to replace back tires more than 2x as often = are not enough long term savings to justify converting one over, nor hardly pays for the faster wearing tires most of the time.

just my thoughts any ways.

Thanks for your input. We are either max gross and then some, or empty. I am no expert on how differentials work but I was under the impression if the power divider isn't locked in, the power is going to go to one axle anyhow. If it is one set of tires per axle at all times then I can certaintly see how that would wear tires 2x as fast.