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On my more-or-less stock 1968 Vw Beetle...why is the steering wheel slipping (to a new position) in reference to the wheels...after installing (two) new TRW steering boxes?

I had the shop install a new adjustable beam and at the same time, a new TRW steering box. Immediately thereafter when I would turn the steering wheel at slow speeds (eg parallel parking, under heavy load), and then later drive, the steering wheel would have "slipped". I'd be going straight but the wheel would be 45 degrees to one way or the other. I found that if I stopped and turned it under heavy load the other direction I could get it to "slip" back to straight.

There was no problem with the steering before though. The problem occurred with first new TRW steering box. The shop said it was the steering box slipping internally. I had them install a second TRW (Brazilian). Still same problem.

There are dozens of suggestions on all of these forums, referenced below. But can someone answer what else could possibly be slipping for my following specific circumstances? Did I get two bad brand new TRW steering boxes? Is the shop incorrect in blaming the steering box, or is it entirely likely (historically probable) that it's the (two) new boxes?

Parts Name/Reference Image (albeit for 1961)
http://images.thesamba.com/vw/gallery/pix/461575.jpg

  1. The steering box, beam, pitman arm, and everything from the pitman arm out to the wheels was replaced.

  2. In 6 years of ownership, the original equipment never slipped before this upgrade.

  3. It slips, and stays, in both directions. In other words, it's not just a flex.

  4. Both wheels stay aligned afterward. No other unusual vibrations, shimmying, etc occur. (seems to rule out slipping at the wheel/ball joints).

  5. The shop has "thoroughly" checked that nothing is visibly slipping, like on the input shaft or on the output shaft/pitman arm.

  6. Inspection of the first "bad" steering box shows no fresh metal scraping on the shaft to suggest slipping over the splining (seems to rule out actual slipping at these junctions which otherwise seem the most likely).

The shop also seemed to think since the pitman arm installed doesn't have the steering stops that I was turning the wheels too far and going beyond the gear in the steering box, then coming back on a different thread. But this isn't what's happening because the problem occurs even with a very small turn of the wheel under higher load.

Thanks in advance for any ideas.

References:

Steering shaft slip (seems most likely?)
http://www.thesamba.com/vw/forum/viewtopic.php?t=595723

New steering box:
http://www.thesamba.com/vw/forum/viewtopic.php

Steering box slip?
http://www.thesamba.com/vw/forum/viewtopic.php

Steering box adjustment 67 bug
http://www.thesamba.com/vw/forum/viewtopic.php?t=609086

Steering wheel slipping on shaft
http://www.thesamba.com/vw/forum/viewtopic.php?p=6735090

TRW Steering Box
http://www.thesamba.com/vw/forum/viewtopic.php?t=243705

http://www.vw-resource.com/steering_box_adjustment.html

  • 1
    I cannot tell you for sure, but it would seem to me the most obvious place you are suggesting is where it's slipping at (the coupler between the steering shaft and the steering box). It will not be happening at or below the steering box, as this would most likely affect alignment and would be very obvious. There are only two places which I can think of where it would be slipping otherwise: where discussed or at the steering wheel itself. I'm pretty sure the wheel end of the shaft is splined. Leads us back to the coupler. – Pᴀᴜʟsᴛᴇʀ2 Oct 29 '15 at 0:43
  • Thanks, I appreciate your time, and confirmation of what I was thinking. – cloudsurfin Oct 30 '15 at 20:18
1

Looking at the picture you have in the first link, the shaft (#27 in the picture) where the coupler (#40) attaches has a notch in it.

enter image description here

Since the shaft is not splined, the notch would serve two purposes: 1) to ensure the steering shaft (red arrow) stays on the notched shaft (#27); 2) to ensure the shaft (red arrow) doesn't turn on the notched shaft (#27). Both of these things are accomplished by means of the bolt which goes through the #40. If this bolt is not big enough around (thick enough), it won't engage the notch correctly. If it isn't engaging the notch, it would allow the coupler and steering shaft to turn on #27.

Also, just thinking about it, you may be able to test where the slippage is occurring by cramping the steering. Run the steering all the way over to the stop (right or left, shouldn't matter), then crank on it a little more. You should be able to tell where the slippage is occurring.

If you still cannot tell, put reference marks anywhere there could be slippage. If you put straight lines on both sides of the possible slip area which start inline, when it does slip, you'll easily be able to tell the difference and know where the slip is occurring.

  • Awesome, thanks for the reply. That makes sense. I read somewhere that different years had different size bolts. I'll mark it as the answer unless I find out otherwise....but there's no way the steering box can "slip" internally, right? – cloudsurfin Oct 30 '15 at 20:16
  • Pictures of the real thing...good lead, thanks. karmannghiarepairs.blogspot.com/2012/04/… – cloudsurfin Oct 30 '15 at 20:35
  • @cloudsurfin - The slippage could be coming from either side of the rag joint. It looks like the steering box has almost the same type of joint on that side as the steering shaft has on the rag joint side. – Pᴀᴜʟsᴛᴇʀ2 Oct 30 '15 at 21:58
  • By "rag joint" do you mean the coupling disk (round rubber thing with four holes in it)? Now that I think about it, the joint with the red arrow didn't change. Are you saying there could be one on the lower side just like it? Because that one would have been replace when they replaced the steering box. I need to track down a real diagram for my year. Thanks again for the help! – cloudsurfin Nov 1 '15 at 1:44
  • Yes, the rag joint is the laminated rubber piece which goes between the steering box and the steering shaft (looks like it could be #26 in the diagram - number is cut off, lol). It's designed to take up some of the vibration which would other wise be transmitted up through the steering column. It looks like there is a coupler on both sides of it. Either side could be slipping. – Pᴀᴜʟsᴛᴇʀ2 Nov 1 '15 at 2:33
0

From the bottom up .....

  1. You could be slipping at the idler-arm to output shaft ... loose bolt.
  2. The steering box needs adjustment for the first 250 miles ... it's on top of the steering box, behind the little black door in the spare tire well.
  3. Your steering couplers, fore-and-aft of the dag-joint. The top ring-clamp can get spread-open, and unable to tighten enough.
  4. Inside your steering wheel shaft, at the joint under the clamp-ring. Sometimes it is smooth and needs to be dimpled with a skinny prik-punch ... to give the female internal something to get an initial bite on.
  5. And possibly .... your steering-box is not tightened enough to you torsion-tube.

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