We recently purchased this truck to work on and off our ranch. It’s rated 46000 GWV, 13’ bed, Tandem axles, CAT C7 engine, Air spring suspension, 10speed transmission. I have some questions about it. 1) When driving down the road empty (never carried a load yet) it makes a “thrumming” sound. The frequency of the sound changes with the speed of the vehicle. The tires are in fair shape, tread depth is around 5/32”. My brother thinks it’s because the tires don’t have all the exact air pressure. The pressure ranges between 85-95 psi in the different tires. Is this the problem, is something else wrong, or it’s just the way these trucks sound? 2) When shifting and I double clutch, it is very hard to get it go into the next gear, particularly downshifting. The road and engine speed has to be perfect before I can get it in gear. I actually find it easier to clutch to neutral and then push it into the next gear (without grinding) when the engine syncs up to the road speed. I help on the ranch on weekends so I am new to double clutching, but all the videos that I have watched on double clutching, this issue doesn’t seem to be an issue. I want to make sure that it’s me and not the transmission that needs work. Thanks
Can't help you with the sound, is it possibly just tire noise. Do you have traction type tires? And where is the noise coming from, front, back, etc? As for shifting no matter which way you do it you have to get road speed, engine rpms synchronized. So that means when downshifting tapping on the accelerator to get engine rpms up. The only times I use the clutch is when starting, stopping, and to break torque when shifting on a steep hill with a heavy load. And some transmissions are just what I call notchy, a little more difficult to shift. We have a 1989 Peterbuilt dump with Detroit 60 series 475hp and 13 speed, and a 2006 KW dump truck with Cat 475 and 18 speed, and a 1976 International boom truck with 290 Cummins and 10 speed. The Peterbilt tranny was replaced with a rebuilt a few years back and was notchy before and after. But the KW tranny is smooth as butter, have never driven a tranny this smooth and have driven a lot of other heavy trucks in my life even 5 and 4's back in the old days. Forgot to add: Do you have a air dump valve in that truck to dump the air out of the air bags? If it doesn't add one. It is better when you are dumping a load to get the air out of the suspension, the truck will be more stable and won't be as likely to tip over. Also make sure you are fairly level when dumping.
I believe they are traction tires, they are for on/off road work. The front tires are the straight groves designed for long haul. The noise sounds like it's coming from the back. There is a dump valve for the air suspension.
The noise could be from flat spots on the tires? Have you inspected them all the way around. I drove for several years. Only used the clutch for starting or stopping. I never could shift the truck with a clutch and had driven several trucks. JJ
Check your driveline for play, I had a drone in my 99 turned out being the spline shaft between the drives! Took to a machine shop and welded an new spline in for half the cost!
noise Lots of good advise, I agree with all of them. If that info doesnt work, jack up both rear axles and put it in gear and see if you hear the noise in the rear axle, then lock the front diff in and see if you hear it then. This would most likely prove whether the bearings are OK in the rears. You can also check the driveline this way. Could be a bad ujoint Shifting, on some trucks, it really takes a lot of practice, with the truck. Most trucks I have run across, that had bad/hard shifting problems, had bad synchronizes, or it took a shift kit (installed with tranny installed) is there a lot of slop in the shifter? I would check the truck out good and find that noise, it may not be nothing but a bad tire, but it could be more serious than that. Keep us posted
Thanks for all the info. I'll keep you posted to what I find out, might be a while posting again, but I won't forget.
Be sure that your wheels have stopped turning before you engage the lock or you could do some damage.Ron G
Is the humm your hearing with a little vibration ? if it is you might have your air spring adjusted a little too high ,this makes the noise and vibration at the transmission ,is reflected through the drive shaft . Can you post what kind of truck and model ,if it is dump, flat or what else , if it was a road tractor converted to a dump ,this could be the culprit ,if this is the case is easy to fix , just adjust the ride hight valve, you could do it your self in a few minutes. I hope this is it. Good luck.
you might have a bad u-joint. i dont think it will be the tire psi. One tire could be seperating or one of your brake drums could be egg shaped causeing it to rub. jack it up and spin the tires and check them good as for shifting it is just you. dont dubble clutch it unless you are pulling a hill loaded push the clutch in, put it in neutral let the clutch out then put it in gear. do this untill you get better then dont use the clutch at all
I find shifting those small cats soooooo much easier with no clutch.
2109 Stang – there is some vibration with the noise. It is a dump truck conversion, from what I don’t remember what the seller told me. I’ll check the air springs. I have the manual from Peterbilt (from their website) that describes how to adjust the air springs. I got the truck (almost) stuck on the ranch this weekend after the rain (central Texas). I can confirm that the differential lock does work, both axles where spinning through the grass while my brother watched. The tires have almost no tread on them so driving through grass makes it very slick. I have some new retreads that came with the truck so I’m going to swap those out. If it is a separating tread then this should resolve it. :update I did notice one bad thing on the truck, one of the dump rails is cracked through the center of the rail for about 5 feet. It looks pretty bad. The question is (without anyone seeing it) can the rail be welded or does it have to be replaced? Thanks.
I would replace it, and maybe Double frame the thing, i bet it was a raod tractor before it was a dumptruck.
Are you talking about the truck frame rail? From your post I am thinking it is a frame rail on the dump box.
Yes it is the frame rail on the dump box. This truck is not used on a daily basis and not for comercial use. Do you think replacing the rail is still necessary? How would welding hold up? What do you think the cost would be to replace the rail?
Can we get some pics of the rail, maybe fish plate it and you would be good to go.
Here is a picture of the rail, 3 pictures down the rail.
I've never seen anything like that to that extreme. How old is the body, any idea? Is the manufacturer ID tag still on the body? If so, I think I'd contact them and let them know of your problem that sure looks like a design flaw to me. What is on the back side of that rail? From the way the cracks are formed I'm thinking something back there contributed to your problem.
I've welded frame rails successfully in the past. Replacing the rail would cost more than the trucks probably worth.
This is the left rail. The right rail has only a small seperation at one joint. I don't know how old the bed is. The biggest crack is where the support post is. You can see this in picture 2, with the post at the bottom of the picture. What is the odds of the dump bed sitting on the post (bed being up) and them them trying to load it. It seems that someone would be out of their mind to do this, but is it possible? Also how dangerous is it to leave the truck in this shape and how soon should it be fixed? The rail looks a little twisted also. Sounds like what this best approach is weld a backing plate on the back side of the rail. I'm planning to take the truck into the Peterbilt shop, is this the best place to take it for this kind of work?
i'd check into getting a new box
In my experience the truck shops are very exspensive. Their hourly rate will probably be much higher than a small welding shop. Check out the rates first. The truck shops up here have heavy duty mechanics who can weld but usually not a dedicated welder. Better to find someone who welds every day for a living in my opinion.
dump body I have messed/redone a bunch of dump trucks and bodies, I have never seen a crack like this and I have seen some bad dump bodies. I keep trying to see what is to the left of the last pictures, that could explain some things. It appears to be a subframe dump body, a bunch of people uses this to keep from double framing the chassis. Its not as good, but it does work. I would like to see a bunch more pictures, but I would contact a goooood welder and he can fix it. If it has a twisted frame, it should be fixed then. If this is a air ride truck, you better dump the air bags before you raise the bed and try to dump on level ground. Lets see some more pictures of the bed and truck.
more pictures are on their way. What is fish plate welding and how is it done? The welder that I have in mind builds big steel buildings and I am guessing that he may not know what fish plate welding is and I certainly don't know.
I think it looks worse than it is. I would gouge it out good weld it up and fish plate it. If you dont gouge it out to the start of the crack and reweld it, it will keep on breaking. If it cracks again you have other problems. Something is out of wack
I have never seen welds cracked like these ,don't take it to the dealership ,too expensive and you'll be surprised of their poor workmanship in most cases ,find a local welding shop ,remember thats what they do everyday metallurgic is their thing . Can you take a picture of the air springs on level ground both axles from the back ,usually in the front differential the springs are lower than the rear, I've got a curiosity . I'm not en expert but I've had trucks with this suspension ,in fact I just replaced the suspension on my T800 with a Peterbilt short air spring susp ,and I'm very happy with the result ,this is my third truck with this susp and I have encouraged a few friends to do the same ,when they have driven my trucks empty and loaded I don't have to say any more . I wish you luck with this truck , hope you can fix the frame rail soon and don't get caught by DOT with those cracks.
Not too worried about DOT it's a farm truck and sitting on the ranch right now until we figure how to fix this issue. Bad thing about this whole issue the truck is not a money maker. We bought it to help us haul stuff on and off the ranch so all it can do is cost us money with no way to recoupe our expenses so mimimizing the cost of repair is esential.
First 3 pictures are on the inside of the rail. Next 2 are the back of the truck the air bags are not inflated.
I wanted to see the air springs photos inflated ,to see if I can judge the ride hight ,in case they were too high ,I'm still thinking on your noise and vibration . I notice that the ride hight valve is on a level position even when deflated ,so just thinking out loud your ride hight might be to low which will cause the same noise and vibration as if it was too high ,the noise that I'm talking about comes from the drive shaft angle being to steep or too low and making your shifting the transmission a little harder ,the gears will stick when trying to go from one gear to another and you will have to physically push the stick a little harder to engage the next gear . so ,can you take another picture of the springs inflated like your last two ? but a better close up on the second from last .
body repair As I have stated that I have repaired a bunch of dump beds, from what I can see this is fatigued metal and its not a problem for a good welder to repair. This looks like eyebeam shaped metal, so just cut a piece of flatbar (maybe 1/2") and about 12" longer on each end (longer than the crack) this is what I call a fishplate and I would do both sides of the eyebeam, where the crack is. I am not a engineer, but this kind of repair has worked in the past on other things. Make sure the metal fits tight, inside the eyebeam before welding. Make sure this eyebeam is straight, before adding a repair, take a straight edge and lay it under the eyebeam frame. If its bent you need to address this first. Now the noise, HUMMMMM not a lot of info to go on, I could list many ideas. As stated it maybe your airbags pumping up and down, Im assuming you have a air bag leveling valve??? Get your Vin number and call the dealer and ask them what the height of the air bag should be, you may have to play with this height until you get it to ride good, it was a road tractor, so the specs will be different for a dump truck. Again make sure you dump the air bags, before you raise the bed. Im sure all the air ride dump trucks I have owned had a equalizer bar, joining the two rear air bags. You can get them from any salvage shops I would still say, make sure its not a rear end noise, wheel bearing, tires-looks like you need some tires. Make sure you buy heavy lug thread, not highway thread, if you are going to be off road mostly. I had a bad ujoint and it was making a funny noise, it was hard to track down, but I finally found the bad one. Post pictures of the truck, showing the bed Post pictures of the air bags inflated, on level ground Good Luck
Lastest Pictures Got back up to the ranch to do some work and all it is doing is raining. I would complain and ask for it to stop raining, but we've had a drought in central Texas for over two years so let it rain. At some point I hope to be able to do some work. Anyways I was asked to post some pictures with the air bags inflated so here they are. Also I'll be doing a lot of driving off road so I'm getting off road tires put on the truck (G177 tread). I took a load of trash to the land fill and surprisingly did not get stuck, but it sure made me nervous when the operator kept telling me to back up. I was thinking "you going to pull me out of this mud?"
truck Nice looking truck Tires, what I call the deep lug tread, will pull better off road, but when the lugs of any tire gets clogged up with mud or clay, they all are kind of useless. Air bags, it does appear you have a adjuster for the air bags (last picture) As stated before, you need a air bag leveling bar. It runs from one air bag to the other air bag (bags in last picture) It looks like one bag is higher than the other in last picture. Park the truck on level ground, (a level parking lot works good) measure from the ground to the bottom of the chassis, close to each air bag. the back air bags should be adjusted where they are about the same. The front air bags should be the same level then, if not something is wrong somewhere. Now to the height of the air bags, I always called the truck manufacture and got this measurement, remember this measurement was not for a dump truck and the manufacture should be able to tell you what it should be for a dump truck. The height is important, so as you dont have too much pressure or not enough pressure. IMPORTANT "ALWAYS EMPTY AIR BAGS, BEFORE RAISING BED" try to be on level ground when raising bed. Dont jerk the truck when pulling out from the load, just pull ahead easy Good luck just be careful
Ranch it looks to me like they did a sloppy job with that suspension ,from what I can see the bag on the driver side is offset to the inside more than the other ,also the best way to know the height of your bags is to put a level on the frame and make sure is level ,if not make the adjustment from suspension valve . I can seat here and give you all kinds of ideas ,but if I'm not looking at the truck is not going to help. A guy that I know built his Ford/Sterlin tractor to a dump few years a go with the original air ride and every since his being twicking and working on that set up ,every shop that he goes to wants to try something different ,adding things to make it stronger, I keep telling him that suspension is strong enough ,that he only needs minor adjustment ,but he keeps going to the people that knows ,the people that deal with this stuff every day (according to him) ,finally his son find out that I've being advising the father for a long time. Well thusrday we were working together and when we got done ,the kid asked me what would you do to correct my swaying problem? ,this was at two in the morning ,we took the truck to a gas station where it was lighted and I showed him what adjustments he needed to make ,now I told him I wouldn't warranteed that it was going to fix it ,because all the ad ons on that suspension but to give it a try ,it was going to be 30 minutes ,well today the kid called me and told me that I could have save them thousands of $ if his dad would of listen to me four or five years a go ,problem fixed .
The truck is on level ground, but not perfectly level. I'll have to find some concrete to park the truck on so I can measure it. Then I'll see about getting the bags adjusted. I took the truck to town and I have more information on the trumbing of the tires. Also the steering wheel is vibrating. When I go down hill and take my foot of the pedel the vibration increases. Going uphill and speed up the vibration decreases. So I am guessing this is a front wheel balance issue.
truck Does your front tires have any excessive wear, cupping out (like on the sides) Did you ever check the driveline, for worn UJoints? I have had the drive shafts put out of time, causing vibrations, If the tires are not worn bad, I have had good luck using Equal tire balance beads. Most big tire shops has this, or they can spin balance them. You might want to have the front end checked out, king pins, tie rod ends, alignment. Now I dont have hills in my area, but Im thinking (could be wrong) when you are going up hill and increasing speed, the driveline is under a load/strain. You let off the strain, the driveline wear, timing, etc vibration, might show up more. Double check the back air bag mounting, something doesn't look right. Does the wear on the back tandems seem even wear, or are some of them wearing on the sides more? If so you might need a all wheel alignment, to set all the wheels in the same direction/angle
Finally Repaired We I took my truck in for the state inspection and 3 weeks later and a bunch of money I got my truck back. I had it at the welding shop 3 times. Once to get the dump bed welded (there is new steel on the inside of the dump rail), once for cracked cross memeber that holds the rear of the truck together and once to repair the left rear air bag. The shop had to call Denver to find out what the ride height should be. Also see the shinny new air level valve, had that replaced also. There where a lot of air leaks that had to be repaired. Had to replace a leaking air valve and I also got new tires for the truck. This repair should last for the next 10 years at least. I think there were also a few other items the shop would have done, but I think they were tired of working on this truck. Also the vibration is gone now. I suspect because of the cracked crossmember the trucks rear end was vibration apart. It was more that I was epecting to pay but I know our truck is in really good shape now. The worse thing that could happen would be to break down on the road. A little (in this case a lot) of preventive care is worth it.