Adding diff lock to a truck without it

[ButchB]

I just bought a mack anthem daycab about a month ago. I was told when I bought it that it had full locking rears. I was a little overwhelmed when I picked the truck up and did not catch the fact that it actually does not have locking rears. It does have a power divider lockout but that's it. I haul logs and really need to be able to lock everything together coming in and out of the woods. How hard would it be to add locking rears now? Thanks

[kt_Engineer]

Do you have Mack axles or Meritor/Dana axles? Changing out to diff. locks will need you to swap out carriers built with diff. lock function (diff. fork, clutch, splined diff. halves - not something you can drill and add to your current carriers) along with axle shafts. Then you will need to add solenoids and have air lines to diff. carriers to activate them. On other end you will need lines to in-cab switch to activate diff. locks. Not a easy job.

[Rob]

Is there any chance Detroit Locker/No Spin differentials could be fitted:

https://www.eaton.com/us/en-us/catalog/differentials/nospin-locking-differential.html

These can be however "brutal" when running Bobtail but they sure will not slip under most any conditions. I've had six in various trucks and they do the job reliably.

[R.E.D]

I woulda thought the anthem somewhat light duty  speced for log hauling , but if you have Mack axles inter wheel and inter Axle lock was an option I believe. 

[ButchB]

When I bought the truck the salesmen knew I was gonna use it for hauling logs but insisted it would be fine. It has Meritor rears. Weird thing is it has a gold bulldog so to me it should have mack rears. I called Meritor and asked about adding a diff lock and he said I couldn't unless I swapped the rears. Considering the gear ratio is 2.47 it might not be a bad idea. 

[kt_Engineer]

On 1/16/2020 at 7:14 PM, ButchB said:

When I bought the truck the salesmen knew I was gonna use it for hauling logs but insisted it would be fine. It has Meritor rears. Weird thing is it has a gold bulldog so to me it should have mack rears. I called Meritor and asked about adding a diff lock and he said I couldn't unless I swapped the rears. Considering the gear ratio is 2.47 it might not be a bad idea. 

Wow...2.47 ratio for logging? Meritor 14x (2.47 is ratio available only in this series. Meritor 160 series tandem has 3.07 as fastest ratio) is a linehaul axle and recommended as an highway only axle typically pulling 80,000 lbs (and depending on grades upto 125,000 lbs in some cases). If you are using a really deep starting transmission gear ratio for off-highway use expect the axle to break soon (thru-shaft, diff. halves etc).

Mack does NOT sell Gold Bulldog with Meritor diff's. Looks like someone swapped out Silver Bulldog ornament with Gold. Does it have T300 manual transmission or mDrive AMT?

[ButchB]

mdrive. i'm swapping it out for a new pinnacle ch. new truck has 3.25 gears, 24.5's, diff lock, and the ability to turn off atc. I hope it does better in the woods than the anthem did.

[kt_Engineer]

1 hour ago, ButchB said:

mdrive. i'm swapping it out for a new pinnacle ch. new truck has 3.25 gears, 24.5's, diff lock, and the ability to turn off atc. I hope it does better in the woods than the anthem did.

3.25 ratio is available in Meritor 14x as well as Mack axle CRD150/151 series. Generally, I would consider this a bit fast for something going into woods and recommend something closer to 3.79 or 3.98. The reason for this is the amount of input torque into axle (in loose sand, packed dirt etc) is much higher than when driving on freeway and faster ratio only makes in worse (hence my previous comment of 2.47 ratio). The increased torque stresses out internal components. If you are stuck in mud and wheels are slipping be careful about using Rockfree or powerlaunch feature. Improper use of these features along with wheel-hop with diff. lock engaged will cause tremendous torque spike to go through system and break axle-shafts, diff. halves, thru-shafts and worst case gears and bearings.

[Lmackattack]

Im not very current on all of the offerings at mack (volvo) but a ratio of 2.47 is way to fast for logging. This sales man sounds like he was selling you a truck he had in stock and needed to move or was just clueless on how to spec a truck for on/off road use. And please take no offense but you should have noticed that highway spec gearing on the agreed build sheet. Im shocked the salesman had the balls to sell you on that..  the M drive has a 14.94 first gear compare that to the old 2 stick 6 speed that has a 14.10 first gear in Lo-Lo with the popular 4.17 rear gear ratio .   These new salesmen seam dead set at selling fuel saving packages. they push this new Low RPM on road spec to everyone. Many of these guys dont understand the need for stability in the off road at max weight limits.  the 3.25 will be better but I agree with KT that its still a fast gear for the off road but the M drive may make use of it? I know if it was manual trans it would be hard on the clutch if staring out in soft sand. the locking rear diff is a nice addition to a truck used in the off road. I thought macks auto power divider was the best until I drove a truck with the locking rear option. the truck I drive now has power divider lock and rear rear diff lock. thing can drive thru anything as long as my front axle dont sink in. it amazed me how much better a truck was with the diff lock option

[ButchB]

Thanks guys. I agree the salesman was just looking for a sale at any cost, and I was dumb enough to fall for it. The manager (Leon McClain) at Mack of Charlotte took the truck back and got me in a new pinnacle CH. I couldn't be happier with the service and the truck from this dealer.