TheSamba.com :: View topic

Fri Sep 19, 2008 9:45 am

I'm new on here so please forgive any mistakes. Also I should mention I'm not the most experienced mechanic, I know a little but I'm 19 and this bus was my first car.

It's a '78 Bay with an automatic transmission, stock suspension, and the 2000cc motor. A daily driver that gets about 50 miles a day.

The vibration is worse at high speeds (65-70mph) but can be heard quietly at 35mph. It also seems to be while the vehicle is under a load: I put it in neutral while going downhill and it disappeared. It is also seems to go away while accelerating. The vibration is coming from the passenger side rear wheel, at least I think it is. The drive axle on that side has fallen off at the wheel side twice now(I know, once is understandable but twice is just dumb, I should have been checking it).
I replaced the wheel bearings hoping that was the cause but it didn't change anything. I had some extra cash so I bought two complete drive axles and still nothing. The bus has new tires and shocks all around. I should also mention that while replacing the bearings I noticed some considerable wear on the stub axle so I replaced that too.

Thank you for your time and help, it will be much appreciated.

Fri Sep 19, 2008 10:10 am

Any change if you put the rear tires on the front?

Fri Sep 19, 2008 10:36 am

no, I tried it and no change. When I had new tires put on(about 800 miles ago) my tire shop sad the rims were fine and everything balanced out.

I should add that the vibration has been there since I started driving the bus about 4 years ago. It was my fathers before it was mine and I believe he complained about a vibration when he drove it but it didn't see a lot of use so he didn't fix it.

Fri Sep 19, 2008 10:57 am

Were the axles you used the correct automatic ones? If you used ones for a standard trans a CV could be over extended or over compressed.

Fri Sep 19, 2008 11:03 am

yeah, I measured them to make sure and they were the right length.

Fri Sep 19, 2008 11:11 am

Right length to replace the unknown ones already installed (and making the same noise) or right (2 different L&R) lengths for an auto bus?

Fri Sep 19, 2008 11:11 am

If the half shafts you bought were asian made, you may discover why they were so cheap.

For about $40 (for 4 "re-pack kits") and a day you can at least remove, clean, inspect , and re-lubricate the CV joints you have to see if they are indeed still servicable.

At least you will be able to rule them out if that is not the problem. Cheap and easy to do.

Be sure to torque them correctly and re-torque them again after about 100 miles.

Fri Sep 19, 2008 11:27 am

The axles I bought were EMPI brand, they were $150 each. I'm not sure what the overall opinion on EMPI brand is. Before I spent the $300 I tried the cheapest solution which you suggested and that was cleaning and repacking my old CV joints(I used black moly grease, that's what was recommended) but I saw no change. After that I tried the next cheapest which was wheel bearings.

Fri Sep 19, 2008 11:35 am

busdaddy wrote: Right length to replace the unknown ones already installed (and making the same noise) or right (2 different L&R) lengths for an auto bus?

Sorry. The correct lengths, I replaced both left and right and made sure the left one went on the left and the right one went to the right. There are two different lengths for an auto bus.

Fri Sep 19, 2008 1:50 pm

Could it be motor mounts?

Fri Sep 19, 2008 2:04 pm

Can't rule out engine mounts, but you would usually get more noise under power or decelerating, look at the front trans mount and pull the fan to see the rears.

How did you install the outer race for the wheel bearings? Hammer or press?

Fri Sep 19, 2008 2:34 pm

Sometimes at start up it idles a little rough and if i immediately put it in reverse, and sometimes in drive, it sounds like something is just pounding around underneath the car, it goes away after I pat the gas a time or two and it smooths out. I think its the transmission, how much play should it have? I can get under the bus and push the transmission up and drop it and almost recreate the sound. Is this just idling or could it be part of the vibration?

I used a hammer and a block of wood, its what I had but probably not what should have been used.

Fri Sep 19, 2008 2:46 pm

If the bearing install went bad you usually notice it in under 50 miles, you can feel the roughness spinning the wheel.

You shouldn't be able to lift the trans more than 1/8" without encountering some serious resistance from the mounts. If you can move yours up and drop it there's a good chance the mounts are loose or worn out. That could very well be your noise.

Fri Sep 19, 2008 3:04 pm

Ok, I thought it had quit a bit of play. Probably about a 1/2" or 3/4". Could that cause the vibration also? Its so rough that the CV joint bolts on the passenger side rear wheel back out periodically and must be torqued back down. Transmission mounts would defiantly make sense except that its isolated to that one side.

Fri Sep 19, 2008 4:18 pm

Loose mounts could cause the vibration, but probaly have little to do with the loose CV issue. Do you have the link plates that go under the bolts? (curved things with 2 holes), are you using a torque wrench to tighten them?

Fri Sep 19, 2008 4:24 pm

I have all three of the link plates in the axle that loosens up, I robed some from the drivers side because when the axle fell off I broke one and lost one. I figured it needed them more. I am using a torque wrench.

Fri Oct 30, 2009 7:09 am

So this thread was my first post. Since joining The Samba a little over a year ago I have been able to fix a ton of things on my Bus and greatly improve its overall performance. BUT, I still have this whole vibration/noise problem.

I'm considering driving my Bus down to Florida this Thanksgiving (from Kentucky). It will be the longest trip I have ever taken the Bus on and I'm just trying to think of everything that could possibly go wrong and this issue kind of scares me.

TheShane wrote: I should also mention that while replacing the bearings I noticed some considerable wear on the stub axle so I replaced that too.

What would cause this considerable wear on the stub axle? Seems like that's not one of those parts that you should ever really need to replace.

I noticed that the 46mm nut was loose (cotter pin still in) so I decided to torque it back down and I stripped the threads WAY before I was even close to the torque spec. If that means anything. Also one reason I replaced the axle.

I'm considering replacing the trans mounts but am not sure when I will get a chance or that they are even the cause. Seems logical for a clunk in reverse but maybe not for a decel vibration like I'm having.

Thanks, guys.

Fri Oct 30, 2009 7:48 am

When you replaced the axle, did it torque correctly? Have you re-checked it since? Any in-out movement when you jack that wheel up? You said you replaced bearings and races on that side is why I say that. In order to isolate your vibration you need to rule out other things by fix/repair. If you still have the slop in the transmission by all means replace those mounts. If it were me I would go as far as to remove the fan and inspect the motor mounts too. You are planning on a trip, let the trip in the bus be your adventure, not the adventure of repairing your bus along the way.

Fri Oct 30, 2009 8:20 am

... try raising the rear tires off of the ground and spin the wheels while you watch the drive flanges at the transaxle (against the transaxle case) to see if one of them bent when the CV flung off.