Rear bump stop - clearance?

[type11969]

I have a 76 westy with a subaru conversion - aka more weight hanging off the back end. Needless to say, I had some sag issues. I just swapped both the inner and outer spring plate bushings, and confirmed that the plates were indexed at 23 degrees. I decided not to mess with re-indexing yet to see how much the bushing replacement impacting things. Ends up bushing placement alone bought me ~0.5" of lift on each side at the wheel arch. But, I'm still basically on the bump stops - pass side is barely touching/engaged (I can wiggle the stop around), driver's side has some clearance.

I plan to re-index, but I'm trying to figure out by how much. I'd like to get back to stock ride height. Roughly how much clearance should I try to achieve between the rubber bump stop and the metal stop itself?

Besides the suby swap, I do have a full tank of gas, but otherwise nothing in the bus (besides the camping interior).

Help appreciated, thanks!

-Chris
_________________
1969 VW Beetle - t4ed indeed
1971 Porsche 914 - jackstanded
1976 Westy - DD

[Wildthings]

The smallest adjustment you can make is 0° 40', so assuming I have the math right the minimum change in the height (H) is approximately

H = L x Sin(0°40')

or

H = L x 0.012

where L is the center to center length of the torsion arm. Two minimum adjustments would be about twice that.

Somewhere there are charts for this.

[type11969]

Thanks, I don't have any questions about the math, or what I need to do to get to whatever target - I'm more curious about the target itself. Ultimately I'd really like to know how much bump stop clearance I should have. I can't imagine that what I have right now is correct, but maybe. Or is 1" more appropriate? Just looking for a rough number.

Certainly happy to use some other measurement metric if there is something better

-Chris
_________________
1969 VW Beetle - t4ed indeed
1971 Porsche 914 - jackstanded
1976 Westy - DD

[aeromech]

Please also consider that after all these years the bars have taken a set. This means that when doing the adjustment add just a bit
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[type11969]

Yep, understood. But given that I'm running with more weight cantilevered over the rear (suby conversion), I'm going to need more than an adjustment to compensate for set. I'm just trying to figure out by how much. I'd rather only have to take apart/reassemble once more. I'm hopeful someone can share a dimension target for stock ride height - like bumpstop clearance or distance from the ground to the torsion tube, or?

-Chris
_________________
1969 VW Beetle - t4ed indeed
1971 Porsche 914 - jackstanded
1976 Westy - DD

[aeromech]

The Bentley gives the numbers. I’m just saying that those numbers are based on new torsion bars. Add a bit to compensate for age
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[Wildthings]

For my van the center of the rear wheels to the lips of the wheel well is about 11". Your van should look like it is sitting down in the back a bit when unloaded. Add two people up front and it will look much more level.

[type11969]

Right, Bentley gives the number for the spring plate angle for a stock bus. My spring plates currently measure at that angle without any adjustment, which means they really haven't taken a set (at least within the capabilities of my measurement equipment). But none of this really matters since my rear end is now heavier (ha ha). I need a new target. I know no one is going to be able to tell me the spring plate angle I should use with this added weight, but I can work through the geometry if someone can share a linear dimension off of a stock bus - like the bump stop gap or torsion tube to ground clearance or?

With some linear dimension at some distance from the torsion tube centerline, I can figure out the spline changes I need to achieve that dimension. Its the best option I have right now to try to avoid setting too high or too low.

Anyone have a few minutes to snap a pic of their rear bumpstop clearance in their non-saggy-rear-ended bus?

-Chris
_________________
1969 VW Beetle - t4ed indeed
1971 Porsche 914 - jackstanded
1976 Westy - DD

[germansupplyscott]

Do you have a way to measure the angle of the Bus with respect to level?

(the 'gap' between the rubber bumper and the stop is not important really. It is significant but it's not a way to measure anything)

You can then calculate the amount of adjustment you need to end up with a level stance. There is debate on whether this measurement should be done with a driver or driver and passenger seated in the Bus. If the Bus is level without the driver / passenger it will be *slightly* nose down with them, this is usually OK. If you are let's say 1.5 degrees low in the rear, then rotate the torsion arm 1.5 degrees in the opposite direction and that will get you close to level.

Count on doing this twice, it's expected to have to re-do even if you have good measuring and math.
_________________
SL

[type11969]

[type11969]

Measuring to the driprail at roughly the center of each wheel indicates that on the driver's side, the rear is slightly higher than the front (1/16") and on the pass side, the rear is basically level with the front. But I also think I read that the drip rail has a slope, so I'm not sure how reliable this measurement is.

I'm also thinking that I should probably drive for a bit with the new bushings to see how things settle before I try to re-index.

Any recommendations for locations to measure bus slope? I've read middle of the slider door opening on the pass side, what about the drivers side?

-Chris

[germansupplyscott]

The bottom edge of the rocker panel should be plum to the Bus however if the Bus has had any rocker work you don't know for sure.

In the repair manual the protractor tool is measuring off the frame. The factory tool is extremely accurate and fine in it's measurements, so much so that it's difficult to measure with any other method and be accurate enough. A laser measuring tool could work. The lower edge of the bulge in the middle of the body could be used.
_________________
SL

[aeromech]

Basically you take your best shot. See what happens. Then redo the job with a change to compensate for the first try.

Tip. Level the bus on stands before you start. I’ve used my iPhone to measure but now I have a digital protractor like we used at the airline to measure flight controls
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[aeromech]

[type11969]

Thanks, I was hoping to avoid iterations but maybe thats simply what I need to do.

I'd still love to see a pic of someone's non-saggy bump stop clearance - who wants to humor me?

-Chris
_________________
1969 VW Beetle - t4ed indeed
1971 Porsche 914 - jackstanded
1976 Westy - DD

[Wildthings]

[aeromech]

Leveling the bus takes just a few minutes and eliminates any potential math errors when measuring the angles.

As far as you looking at someone else’s bus I can’t see that to be much help since your weight is different. Using the most accurate tools available will only get you in the ballpark because of the years. You’ll need to “baby up on it”.
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[richparker]

[Wildthings]

[aeromech]

Better start selling those or it won’t matter because no one else has one
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound