Rear Torsion Bar Adjustment

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vwlover77
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Rear Torsion Bar Adjustment

Post by vwlover77 » Tue Jun 08, 2010 5:43 pm

I found this thread over on the "other forum" about the rear torsion bar adjustment (scroll down a ways to see the illustrated procedure).

http://www.thesamba.com/vw/forum/viewtopic.php?t=399837

Is it in fact necessary to disconnect the brake hoses and loosen the e-brake cables to move the bearing housing rearward?
Don

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78 Westy
71 Super Beetle Convertible Autostick

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Re: Rear Torsion Bar Adjustment

Post by Amskeptic » Tue Jun 08, 2010 6:31 pm

vwlover77 wrote:I found this thread over on the "other forum" about the rear torsion bar adjustment (scroll down a ways to see the illustrated procedure).

http://www.thesamba.com/vw/forum/viewtopic.php?t=399837

Is it in fact necessary to disconnect the brake hoses and loosen the e-brake cables to move the bearing housing rearward?
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Chloe - 1970 bus . . . . . . . . . . . 206,845 miles
Naranja - 1977 Westfalia . . . . . 112,885 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 1991 Lexus LS400 . . . 78,899 miles

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vwlover77
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Post by vwlover77 » Sat Jun 12, 2010 11:36 am

Well, the job is done!

I started with the driver's side. The bushings were so worn that the spring plate hub had worn a groove on the inside of the cover!

The Bentley claims a 20 degree target angle for the spring plate (Campmobile after chassis # xxx) , but as saggy as it was, it was still reading 22 degrees after frame rail compensation. So, I decided that 23 degrees was probably the correct target value and went one click clockwise on the inner spline and one click ccw on the outer spline.

Getting the spring plate back on the torsion bar was a struggle. The parking brake cable sheath made it hell to get the carrier and drum far enough back to be out of the way of the spring plate. (I had already removed the adjustment nuts from the cables at the front of the Bus.) Many attempts, a little muscle, and a lot of sweat later, it was on. Was I supposed to completely remove the parking brake cables from the rear brakes?

The passenger side measured 23 degrees after frame rail compensation, which validated my decision on the driver's side. I left the settings as they were and just installed the new bushings.

I'll post some photos of how it's sitting soon. I still think the driver's side is a tad low, but it might just be my imagination. Maybe I should have gone two clicks on each end.
Don

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Post by Amskeptic » Sun Jun 13, 2010 7:26 am

vwlover77 wrote: The parking brake cable sheath made it hell to get the carrier and drum far enough back to be out of the way of the spring plate. (I had already removed the adjustment nuts from the cables at the front of the Bus.) Was I supposed to completely remove the parking brake cables from the rear brakes?

The passenger side measured 23 degrees after frame rail compensation, which validated my decision on the driver's side. I left the settings as they were and just installed the new bushings.
I removed the cables on TrollFromDownBelow's bus, and it was a lot easier.

Do not start second-guessing the factory specifications too much. Why did your actual settings already prove that your Torsion Bars Were Not Sagging? Is it an aesthetic? Have you pored over factory literature, brochures, etc, to see how the Campmobiles actually sit? Apparently VW wanted the campers sitting a little lower to maintain some all important Center Of Gravity with poptop and interior fitments taken into consideration. Respect it. Enjoy your happier CV joints and boots with the lower axle angles.

I will say that the position of the wheel bearing housing and diagonal arm against the spring plate affects final ride height, and I use this small amount of leeway to correct from side to side. You jack the bus up until the spring plates just contact the lower stops. Then you go a smidge more until the tires just unload from the pavement by a millimeter. Loosen the four Big Bolts a bit. Pull down on the lower shock and diagonal arm if you do not want to change the camber and tighten one of the bolts to "tack". Then retighten all the rest. This rotates the diagonal arm in relation to the spring plate, which increases ride height by a very small amount.
If you want to remove a little camber, you just pull down on the diagonal arm and retighten. If you want to add negative camber, you release the jack until the tires just touch the ground, and a millimeter more, then tighten.
Colin
BobD - 1978 Bus . . . . . . . . . . . 112,660 miles
Chloe - 1970 bus . . . . . . . . . . . 206,845 miles
Naranja - 1977 Westfalia . . . . . 112,885 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 1991 Lexus LS400 . . . 78,899 miles

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vwlover77
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Post by vwlover77 » Sun Jun 13, 2010 4:12 pm

Colin, you may remember from our visit to Sean that the sag on the driver's side of my Bus had you wondering if perhaps my torsion bar had broken!

I'm not sure why the factory setting on mine seems to be correct at 23 degrees versus the Bentley spec of 20 degrees, but here are photos of the results. I believe the appropriate amount of unladen nose-high attitude has been preserved.

Image
Image
Don

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78 Westy
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"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Post by hambone » Mon Jun 14, 2010 7:33 am

How come the rear torsion bars don't need lubrication like the fronts? Something to do with front wheels turning left/right and grease flowing from the joints?
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Post by vwlover77 » Mon Jun 14, 2010 8:11 am

Aren't the front torsion bars a stack of individual "leaves" rubbing against each other as the "bars" twist? I think that's why they need to be lubricated. The rear bars are a round, one piece bar.
Don

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78 Westy
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"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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chitwnvw
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Post by chitwnvw » Mon Jun 14, 2010 10:24 am

Is there an exploded mechanical view anywhere? I'd like to try and get this straight in my head.

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vwlover77
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Post by vwlover77 » Tue Jun 15, 2010 9:48 am

Here's the setup in the rear. (This is for a Beetle, but close enough.)

Image

25: Torsion bar with adjustment splines on both ends
26 and 28: Rubber bushings
27: Spring plate (the bearing carrier and diagonal arm bolt onto the end of it)
29: Spring plate cover

The front suspension is the same conceptually, except there are two torsion "bars" per side, an upper and a lower one. They don't have the adjustment splines like the rear, though. And, the "bar" is actually a stack of rectanguler leaves, not a solid bar like the rear.

Image

Image
Don

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78 Westy
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"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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vwlover77
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Post by vwlover77 » Mon Aug 02, 2010 9:40 am

Well crap. Even after the adjustment, the driver's side of the bus is still definitely lower than the passenger side. It's very obvious when viewing the Bus from behind.

I'm thinking one of two things:

1. That my attempt to go one "click" at each end of the torsion bar did not work and I ended up putting it right back where it started (does not seem likely)

or

2. The torsion bar has weakened and is not as springy as it should be so that setting the plate to the proper angle when free does not result in a good laden height.

Is #2 a possibility? If so, should I replace the bar or just dial in some more angle?
Don

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78 Westy
71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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patayres
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Post by patayres » Tue Aug 03, 2010 4:08 pm

I'm not sure why the factory setting on mine seems to be correct at 23 degrees versus the Bentley spec of 20 degrees
Did you measure the diameter of your torsion bars when you made the adjustment? If you look at my thread on TheSamba you will see that my Westfalia-bound Kombi somehow left the Hanover factory with the lighter duty torsion bars, which call for a larger spring plate angle. It's possible your bus also has the lighter duty bars.
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vwlover77
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Post by vwlover77 » Tue Aug 03, 2010 7:29 pm

I did not check the bar diameter, but started with the driver's side and found its angle at around 22 degrees to start with. Saggy as it was, I figured 23 was the correct setting versus the Bentley spec of 20. The passenger side was already at 23 so I left it alone, and it appears to be fine on that side.
Don

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71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Post by Amskeptic » Wed Aug 04, 2010 9:23 pm

vwlover77 wrote:I did not check the bar diameter, but started with the driver's side and found its angle at around 22 degrees to start with. Saggy as it was, I figured 23 was the correct setting versus the Bentley spec of 20. The passenger side was already at 23 so I left it alone, and it appears to be fine on that side.
You have a Hail Mary adjustment. Jack the left rear tire off the ground by an inch. Loosen the four bolts sandwiching the spring plate between the diagonal arm and the wheel bearing housing. Pull the wheel bearing housing down In Relation To The Spring Plate. Do not let the diagonal arm follow if you can help it, or you will have camber issues (though if you have too much negative camber, why not let it come down a bit?).

Tighten the four bolts and see if it helped.
If you have to disassemble the whole mess, add a half a degree to the current left setting and let us know if that helped.
Colin
(make sure you are not being visually fooled like I was with my Dansk heat exchangers which made the muffler hang crooked making me think that the right rear was droopy)
BobD - 1978 Bus . . . . . . . . . . . 112,660 miles
Chloe - 1970 bus . . . . . . . . . . . 206,845 miles
Naranja - 1977 Westfalia . . . . . 112,885 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 1991 Lexus LS400 . . . 78,899 miles

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