haulin-gas

Well, it's heading into the frame shop in the morning. Hopefully they'll finally find out what's wrong with this thing once and for all!

Thanks to everybody for your ideas. At this time they are no closer to finding a cure, or the cause for that matter. I have been assured that the engineers at Mack are working on the problem, but they are being very tight lipped about the whole thing. Wouldn't want word of this getting out to the FMVSS or Transport Canada, eh!

Makes me feel a whole lot better knowing that after I lose control and roll it that the engineers have got my back!

I'm sure MACK checked it, but I'm just curious, has anyone ever checked to see if the chassis rails to cross members all bolted or riveted to correct specs? I did a few D-500 Dodges in the 80's that wandered all over the road. We found the chassis rails were moving because there was a miniscule bit of movement between the rails and the cross members. We found the rivets compressed did not expand completely "tight" in the holes. The rivet diameter was a few ten thousands smaller than the holes. We set the chassis up on a chassis machine to "square" it and re fastened the cross members. Just a thought. Paul

Interesting point. I just did my weekly crawl thru and noticed that the crossmember just behind the transmission is showing signs of rust between where the gussets are riveted to the crossmember. Can't turn the rivets with a vise-grip, but they could be tight and just wandering around in slightly oversize holes. Along with all the other issues on this p.o.s. I think it's time to have a little discussion with the dealer. Best place for this truck is parked against their fence, far away from a public road!

My experience is our customers are suprised how good the trucks pull. We even have MP7's pulling 80,000 and no complaints. Yours may not have been spec correctly for the application. Have seen people by trucks from other dealers and not happy with the way the truck pulled due to it is not spec correctly for the application.

CHU, MP8-505C, T318LR, S40's @3.98 with 24.5 rubber. Speced by Mack for pulling 140,000# up to 8% grades. Top end power is ok, but it's the 1760 torque that causes the lack of bottom end holding power. Our company trucks have 550 Cummaparts with 2050 torque. Top 4 gears I can keep ahead of them but below that they're around me and gone.

Have seen a few new trucks get dropped while being undecked after transport .

This one was the pull truck so that wasn't the cause. My last Pete came up piggy backed and they had to replace the front springs. It had the air ride steer axle in it and the rear sections behind the air bags were both snapped off when the set her on the ground.

Changing a TRW box on a 2014 CXU today. We have no problems out of the Sheppard M series on the new trucks. One of our death wobble/tire wear problem CXU's had its steering box changed when it was a month old.

So, is it possible to switch from a TRW box to a Sheppard without any modifications? One thing we have noticed on this P.O.S. is that the left steer axle spring is somewhat sagged compared to the right, and has been since I took delivery. Any thoughts as to this affecting the wandering issue? Mack parts guy says there are 2 different springs that are used in the CHU. On has a higher load rateing than the other and he thinks it may be possible that the factory screwed up and mismatched the springs on the assembly line.

In my notes here, My DSM said to make sure the caster is 3 to 3.5 degrees before installing the bronze bushings and steering stabilizer. This axle has been around and not changed since around 2005. Really dont know why we are getting all the complaints of "death wobble" and tire wear. Dont know what has changed lately. We also have some bad cab shake complaints on the full flaring day cabs whne following a van trailer. I have test drove and verified the cab shake on a new day cab and it was scary! mack does have a fix for that issue.

Beginning to wonder if there's an issue with the steering boxes. Two of us have had the boxes changed before 50k miles and within that time they both needed to have the sector shaft play adjusted. Before they changed my original steering box, it went from nice and snug to over 1/4 turn of free play in the steering wheel, followed by the shaft seal letting go.

Did TRW start assembling their boxes in a 3rd world country lately?

There are some new top secret bronze bottom king pin bushings that just came out. The dealers DSM should be contacted and get the new bushings installed. Part # 4103-7421416557. This is for the FXL sealed hub style axle.

Thanks for the info. Just talked to the service manager, since mine is in the dealership with the tranny out for the second time in 3 weeks, and he asked me how the hell I found out about the bushings since they only heard about it this week.

Too funny.

wheeler73, these are the "after alignment" readings. And yes, the suspension check has been done as per the bullitin on the twin Y

wheeler73, these are the readings from the last alignment check. Steer axle- Left side Camber= -0.3 deg Caster=3.8 deg Toe= 0.03 deg

Right side Camber= +0.3 deg Caster=4.6 deg Toe=0.04 deg

As I mentioned earlier, the alignment has been checked twice by 2 different reputable shops.

wheeler73, if you mean dampening cylinder kit, one of the guys I mentioned has had that installed at the dealership and it didn't make any difference at all.

Drives line up perfect. Thrust angles are dead on. It's got the new Twin Y suspension on the back and Mack 14200 steer axle. I know of 2 other owners of the same model having the same problem. One has Hendrickson and the other has NeWay suspension.

Loaded, empty, bobtailing seems to be no difference. Tried 5th wheel in various positions and it makes no difference. Steer axle weighs 5400-5600 kgs (11900-12300#) all the time, depending on fuel level.

I'm the very disappointed owner of a 2014 CHU that wanders all over the road like a coyote chasing gophers from ditch to ditch. Have had alignment checked twice at 2 different shops and they both say it's good. Steering box has been replaced under warranty and it didn't help at all. Got rid of the factory Bridgestone steer tires and replaced with Michelins which improved it slightly, but still darts side to side at the slightest rut or twist in the road.

Oh yeah, forgot to mention it only has 80,000km on it. Anybody have any ideas, cause the dealership sure don't?