[Teal 95 KW]

If you're going forwards I wouldn't worry about your mudflaps dragging going down the road...I've dumped the air in my truck/trailer going down the road before to clear a bridge I wasn't sure about. You can always fold your flaps back and bungee them up...then you won't have to worry about anything

[allan5oh]

Originally Posted by SteveBooth

I thought about doing that but wasn't sure what would happen and if it's ok. I have a feeling my mud flaps will drag a lot if I do it though.

You DON'T want to go that low. Just a half inch maybe. At most an inch.

When your parked, hit the dump and quickly run outside, see how fast it dumps.

Every load is different of course, because of different weight.

Originally Posted by allan5oh

You DON'T want to go that low. Just a half inch maybe. At most an inch.

When your parked, hit the dump and quickly run outside, see how fast it dumps.

Every load is different of course, because of different weight.

I just went outside and dumped it and it went down about 2 inches and the mud flap was bent over. I'll probably try this when I head out of here empty. I'm right next to the highway and 75mph speed limit.

Not sure what this will prove though???? Hints?

[allan5oh]

I was talking more about how much time it takes to dump. If the whole thing takes 15 seconds to dump, don't dump it more then 5 seconds on the highway.

What you're doing is changing the driveshaft angles "on the fly". If they go away, you have too much air in your bags. You should check with western star(or freightliner) on how to check your ride height. It can be a little tricky. Doing the dump on the highway is the lazymans way.

You could also just look at your u-joints, especially the back driveshaft. Do they look totally straight or cocked just a bit? Now dump the air, look at the driveshafts again. That's how much ride height affects driveshaft angles, a lot on most trucks. Some more then others. With my volvo, it's crazy how much it affects it(hendricksen suspension). On a 8-bag kenworth, it doesn't affect it anywhere near as much. There's no trailing arms.

If this has already been looked at, disregard this message. It will self-destruct in 30 seconds.

Originally Posted by allan5oh

I was talking more about how much time it takes to dump. If the whole thing takes 15 seconds to dump, don't dump it more then 5 seconds on the highway.

What you're doing is changing the driveshaft angles "on the fly". If they go away, you have too much air in your bags. You should check with western star(or freightliner) on how to check your ride height. It can be a little tricky. Doing the dump on the highway is the lazymans way.

You could also just look at your u-joints, especially the back driveshaft. Do they look totally straight or cocked just a bit? Now dump the air, look at the driveshafts again. That's how much ride height affects driveshaft angles, a lot on most trucks. Some more then others. With my volvo, it's crazy how much it affects it(hendricksen suspension). On a 8-bag kenworth, it doesn't affect it anywhere near as much. There's no trailing arms.

If this has already been looked at, disregard this message. It will self-destruct in 30 seconds.

Ok, maybe I'll give it a try in a few and take her out for a spin down the road. All my U joints were just replaced and the drive shaft had new whatever you call those things welded on and then balanced.

[allan5oh]

OK did that make any difference having the driveshafts worked on?

If it's the ride height, I'll be severely disappointed in all the shops that worked on your truck trying to find the problem.

Originally Posted by allan5oh

OK did that make any difference having the driveshafts worked on?

If it's the ride height, I'll be severely disappointed in all the shops that worked on your truck trying to find the problem.

Nope, the driveshaft work made no difference at all other than all my U joints were broken so you could look at it as preventative maintenance.

I just got back from a ride down the highway and of course the problem would not happen. It takes like an hour or 100 miles for whatever to heat up then it starts. Ride height could be the problem I guess since they are made out of rubber which would be prone to heating up and characteristics changing.

I did dump my air 2 times and at least the truck didn't fly off the road or anything else strange.

How do they check ride height?

[allan5oh]

It's a bit of a process.

On my truck, the ride height is the heights between the middle of the axle, and the bottom of the frame rail.

You need to measure:

A = The distance from the bottom of the frame rail to the ground
B = The distance from the middle of the axle(I take the chrome axle cover off, there's a little point in the middle) to the ground

A - B = C, your ride height

Since different tires vary how high your vehicle is, you need to eliminate the tire height, and that's what we do by taking B from A.

I know for volvos, there are 4 different ride heights, depending on which axles you have, and a few other factors. Your ride height is supposed to be within 1/4" to maintain proper driveshaft angles.

If your u-joints were in bad shape, odds are that your ride height might be off.

[allan5oh]

I'll tell you what, from what you've said it definitely is *NOT* tires. Tires do the opposite, they'll vibrate when cold, when they're warm they're OK.

I've heard out of balance drive tires causing a vibration, but steer tires is much more common.

Next time, try dumping the air for a few seconds until it just STARTS to vibrate. If it's the same vibration, then your ride height is off.

Another thing, for some reason different loads will affect u-joint vibration. I've never figured this out, because the ride height should always be the same. I found the worst driveshaft vibration was when I had an empty trailer. Wouldn't happen bobtailing or with a full trailer.

When I'm bob tailing it happens even worse and at lower speeds. I really don't know if it's coming from the front or rear. It's not really a vibration either it's more like a bounce or shake and the frequency increases with speed. I can set the cruise at 75 and it's going to beat the band then all of a sudden it goes away for seconds or minutes. It never happens when the truck is cold and takes a while to start doing it.

I will try dumping the air when I leave here and the truck heats up and let you know. I have a feeling my best bet right now will be putting a camera on the truck and filming each axle and the rear end so I can at least isolate the area.

It may be happening at lower speeds but it's just not noticeable.

It has to be rubber related because it only happens after things heat up.

It can't be the tires or it would happen at a certain speed and would not come and go.

As soon as I get some video I'll post it.

I have a feeling I'll be dead heading out of here tomorrow and heading East where things are a little better.


Say what? Nap time? Ok, I'm coming.....Zzzz