Driving on washboard.

marchesi · 12-18-2008, 09:02 AM

This might be a dumb post but it's worth a try... What is the secret of driving on washboard? My theory was to drive at the magic speed that seems to stop the rattling. Depending on the size of washboard I have gone up to 60 MPH. However, recently I blew my shocks (not sure that was the reason however). Are there any tricks to reduce the effects, both on the rig and on the bones?

scatter · 12-18-2008, 09:19 AM

As far as I'm concerned, it's all about tire size and tire pressure. Not worth changing your tire size just for that, but the larger the tire and the smaller the rim diamerer the more rubber you have to flex and the better the ride. That being the case, I drop my pressure till I have a good bulge in the sidewalls. Then vary the speed till the ride is less worse. I've done a lot of talking with the major tire companies, and their only concern with doing that is heat buildup from sidewall flex. The lower the pressure, the lower you need to keep your speed. Just get out once in a while and put your hand on the sidewalls. Warm is fine. If it starts to burn your hand, that's too much heat. You also increase the chance of sidewall damage on offending road objects and rolling the tire off the rim. But, in many years of reducing pressure (I usually end up with 20-23 psi on the SMB) I've never hurt a sidewall or rolled a tire.
Just my methods - use at your own risk

adventureduo · 12-18-2008, 10:18 AM

I would echo Scatters advice almost exactly. One thing i would also mention about airing down and covering miles .. is always keep an eye out for something that may be in the road or crossing. If you have to make a quick move at any reasonable speed while aired down you'll be all over the road and quite possibly roll the rig.

That being said, in certain situations i've done 60mph on wash board with a trailer and other times 25 without. Just depends how far you can see ahead and if you know the road. There's always a risk.

jage · 12-18-2008, 10:22 AM

Don't fret that the shocks are blown. I'm pretty sure the SMB conversion is too much for the shocks they put on.

Also inspect your cabinets, etc. The vibrations, whether doing the magic speed or not, like to back out all those screws that haven't been glued in... lost my shelf in Death Valley coming back from Racetrack that way.

marchesi · 12-18-2008, 10:44 AM

I agree with you about the shocks. When I had them replaced I was told the same thing...

j.whitbread · 12-18-2008, 10:58 AM

It's frustrating isn't it.

4x4 pick up trucks don't rattle nearly like vans with the same tires but the bed and cab are separate. I think it's a combination of the van body and sitting almost directly over the front wheels.

I think better springs like Deaver would help. I air down and marvel at how the thing stays together.

jage · 12-18-2008, 11:32 AM

If anyone wants to fund a trip to DV in January I'll be glad to go back and give a pre/post Deaver spring evaluation of the road to racetrack!

**daveb** · 12-18-2008, 01:52 PM

Quote:

Originally Posted by marchesi

What is the secret of driving on washboard? ?

I always disconnect the front sway bar which helps a bit.

Usually I just air down and slow down. you have to be careful when airing down. My van comes in at 12K and I have E rated tires but I still slow way down at low pressures. Sliding sideways off the road can get you in a bind.
DaveB

yvrr · 12-18-2008, 03:38 PM

I have generally found that 35 psi and 35 mph tends to work. We have a Hella TMS and I turn it off when airing down. But I stop occasionally and turn it back on to check tire temperatures. Fortunately, many of the wash boards are created by vehicles with smaller tires and our larger tires can sometimes ride the top of the "waves"...

marek · 12-18-2008, 04:23 PM

The basic principles of washboard driving have been mentioned, but I can't emphasize enough the importance of shocks. Having really good (expensive) shocks makes a huge difference. The difference is not just in the speed at which you can travel, but also in your ability to stop.

With soft tires, you effectively skip across the bumps and at certain speeds, this feels smooth. Stopping is now the trouble. Good shocks (and good springs) will allow the suspension to better absorb the bumps and will keep the chassis more stable. This keeps your tires on the ground and gives you better stopping and cornering ability.