Suspension Advice

A comment from the generally clueless (me). Do you have a pressure differential in the tires? I run 24 in the rear & 20 up front for this reason.
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will give that a try.  currently 32 all around

32 is WAY to hard. Vintage Speedsters recommends 22 front and rear. Some on here have gone a tad softer, some as low as 18 iirc) in the front and a little more firm in the back. At 32 in the front you'll get jostled around at every bump.

I remember also reading about using shims in the front to change the angle but that's a technical question for someone who knows what they're talking about.

They're called caster shims, Robert, and you put them under the bottom beam to increase the caster which is lost when lowering the front via torsion bars. Buy 2 thin sets or 1 thick set, Richard. Stock caster is somewhere around 2 1/2- 3 degrees, depending on how much the front came down the car may have none at all (or be negative) and for safe highway speeds (and slightly above)  aim for at least 4 degrees.

PS- stiffer front shocks will only make the front ride harder, and is not the answer; some stock oil shocks will do it, but because your car is lowered with the beam you may need to find some that are slightly shorter (I believe Aircooled.net has them). Get a front sway bar on it, and listen to the guys and lower tire pressures, with slightly softer in the front. Al

Castor angle is also very important for straight-line stability.  Ask me how I know.

ALB posted:

They're called caster shims, Robert, and you put them under the bottom beam to increase the caster which is lost when lowering the front via torsion bars. Buy 2 thin sets or 1 thick set, Richard. Stock caster is somewhere around 2 1/2- 3 degrees, depending on how much the front came down the car may have none at all (or be negative) and for safe highway speeds (and slightly above)  aim for at least 4 degrees.

PS- stiffer front shocks will only make the front ride harder, and is not the answer; some stock oil shocks will do it, but because your car is lowered with the beam you may need to find some that are slightly shorter (I believe Aircooled.net has them). Get a front sway bar on it, and listen to the guys and lower tire pressures, with slightly softer in the front. Al

See, I knew someone with more technical smarts would answer that question. But hey, at least I knew shims had something to do with it. LOL

Caster shims like they said above, but ALSO GET A STOCK VW SWAY BAR.  Do not get an after market stiffer/bigger sway bar.

And make sure both rear shocks are good and torsion set up in the rear is even.  If it wants to steer when you hit dips at 60mph, the rear could be the problem. 

Start at the front and then address any issues at the rear.

 

 

It took 6 degrees negative to get my car to act right over 60mph. It steers hard in parking lots lots now but I guess that's a trade off. I run 18 psi front and 22 in the rear. My car is higher in the rear to keep from draging on everything that's not level too.

Bruce

Thanks folks.  Many great ideas to try.  I did drop the pressures to 26/29 and could tell the difference.  Will play with lower pressures in stages.  Its hot here in Florida but with the fan on oil cooler keeping the oil temp around 180 and cylinder head temp at 200.  What's the trick to keeping these scat valve covers from leaking?  I've tried both rubber and cork.  Thanks again.

richard posted:

Thanks folks.  Many great ideas to try.  I did drop the pressures to 26/29 and could tell the difference.  Will play with lower pressures in stages.  Its hot here in Florida but with the fan on oil cooler keeping the oil temp around 180 and cylinder head temp at 200.  What's the trick to keeping these scat valve covers from leaking?  I've tried both rubber and cork.  Thanks again.

I think most of the guys are running stock valve covers for the most successful least amount of oil leakage.

OK, so 26-29 is STILL way too hard.  The car weighs slightly less than a stock VW (which ran 22-24) so run 24 front 26 rear, TOPS  (and even that is on the stiff side for what looks like 185 tires).

Richard wrote: "What's the trick to keeping these scat valve covers from leaking?  I've tried both rubber and cork."   As alluded by someone else......You can't get a SCAT cover to be leak free.  It's simply the fact that the covers aren't close to flat at the flange.  

Some of the CB Performance covers can be made to be sort-of leak free, at least for 2-3 days, and certainly the stock VW covers (NOT aftermarket, but real German VW covers) with the baling wire retainer seal up nicely.  Who's gonna be peeking under your car to look, anyway?  Distract them with the interior, or tires, or something else.

Just remember, when the VW was new, back in the '60's-70's, they were NEVER leak free, especially at the valve covers.  Hate to break it to ya, but you still have bigger fish to fry as you finish your car.

BTW:  That matt black paint is friggin' AWESOME!  If the engine leaks a little, just tell people it's the awesomeness leaking out.......

OK, seriously......On the valve covers, try using a CORK (brown) gasket, and thoroughly coat the gasket with automotive grease to get it moist.  don't drown it, but get all surfaces thoroughly wet.  Hang it up somewhere for an hour or so (I use my bench vice handle), then lightly wipe the excess grease off of it.  You want to give it time to absorb the grease and swell just a bit.  The black, composite gaskets will not absorb the grease and seem to be a bit more difficult to work with.

Then, install it as usual, but beware that it may have swollen a little bit and you'll have to be careful that it doesn't bunch as you install it 'cuz if it does, it will REALLY leak.

Tighten your SCAT cover bolts (make sure you use NEW bolt o-rings.....I make mine out of 5/16" ID fuel line so ask if you need making instructions)   I get them 1/4 turn tight from loose, and then keep tightening 1 to 1-/12 full turns and stop.  That usually does the trick.

Good luck.

Lane Anderson posted:

Castor angle is also very important for straight-line stability.  Ask me how I know.

How do you know?

Tire pressure:  22/26 is perfect for 185 tires.

 

Lest we forget.

This is from page 17 of the 1968 VW owner's manual. Yeah, those were skinny bias ply tires, but that was a stock, unlowered suspension, too. If anything, our springing is stiffer, with less travel.

I refused to believe this, and kept lowering front pressure bit by bit until I finally got down to about 18 psi. Only then did my teeth stop rattling and did the fronts stop skittering across every pebble in the road. We forget how light the front end is compared to modern cars. We also forget that a lot of the compliance in this suspension was designed to come from the flex in the tire sidewall. They didn't know what a 40-series tire was in 1968.

 

 

The only thing we have to remember is that radials react a little different to pressure, and 16 or 17 lbs for the front tires may be a little soft (no matter how light the front end is), so if you start with 20/24 lbs you know you're in the ballpark and can experiment from there.

I run 16-18 lbs front and 24-26 rear with 165/80/15 radials and one set of caster shims in a beam that's set to run about an inch or 1 1/2-inch lower than stock. It's an adjustable with full "up" travel (i.e. "stock setting") and all 12 small torsion leaves removed. Stock sway bar, rubber bushed. Caster is about 3 degrees positive. Front camber is about -.5 degree. Toe-in is stock, 3/16 or so. (Rear camber is about 1.5-2 degrees negative with nominal toe-out) The car tracks fine through 85 mph. I lose faith there though, not because of any wandering behavior, but because at that speed I suddenly remember what the hell I'm driving.

 

I run 18 & 28 with 175/70 tires.

Richard:  You inundated with info yet?

Here are the proper tire pressures for stock VW's from the "Rob and Dave" VW site for both Bias and Radial tires - a site I would trust and everything Rob says about tire pressure is right on.  Our cars are a tad lighter so it would be fine to drop both front and rear radial pressures by 1psi to lessen the teeth jarring going over road cracks and stuff:

http://www.vw-resource.com/tires.html#pressure

On the "Wandering a bit in the lane" thing.....

Playing with the tire pressure isn't going to fix this, because the car is following the crest of the lane and the crest moves around a bit from past traffic pounding the roadbed.  ALB mentioned half of the cure, and that is placing caster shims behind the lower torsion bar tube on the front beam.  When the car is lowered from the stock VW height, it throws the front end alignment out for lower caster because of how the suspension is designed.  On modern cars, no big deal - the alignment tech adjusts for this with eccentrics designed in to the front end suspension.  Just crank a bolt until the correct caster is reached.

On these cars, using front suspension design from the 1930's, Caster is adjusted mechanically by adding or removing shims (thin metal plates shaped as is the torsion tube).  

Also, if you got it aligned as a VW beetle sedan, rather than a Karmann Ghia, then it's farther out of where you need it to be (the Ghia was a lot closer to our Speedsters in a lot of ways, alignment being just one).  So for the second half of the equation, you're looking for 5 to 7 degrees negative caster in the front end, with the rest of the VW alignment specs remaining the same.  More caster means straighter tracking in lane, but more caster also means more steering effort at low speeds (like in a parking lot) so there is a trade-off.  Even at 7 degrees caster (which I'm running) it's not like steering a truck......more like a car without power steering, which it is.

It is important (at least to me) that you find an alignment tech with experience with old VW Beetle front end or 4-wheel alignments, especially since these are often older chassis cars which need TLC - for instance, to get my front end caster even, I needed 1-1/2 degrees more on one side than the other.  Much of what he'll need to do is no longer done on cars, and caster shims is a biggie.  Also, mechanically moving the rear wheel hubs to get proper rear toe-in or adding rear shims for rear Camber adjust will be pretty foreign to younger alignment techs as they've never seen such things.  For alignment specs, if you have a swing-arm car then use 1966-67 VW sedan or Ghia.  If you have an IRS car, then use the specs for a 1971 Trailing Arm front end, NOT a MacPherson strut front end (the alignments are different).

Oh!  and someone mentioned different caster shim thicknesses - Very true.....They come in two different thicknesses but, believe me, your alignment guy will not have any of them in stock and they're pretty cheap, so get 2-3 sets of thins and 2-3 sets of thicks and bring them with you when you get it aligned.  We ran out when doing my car and substituted a piece from the pole of a chain-link fence for a wicked thick shim and were in business.  Wish I had a photo of "Tony" who did my last alignment. Did a fabulous job with his Mohawk and tattoos and I was so pleased with the alignment that I dropped off a case of Micro-Brewed beer for him and the gang.

Find someone in your local VW club(s) and ask who those folks go to for alignments and then go there.  Same for a good engine guy, too.

Gordon- the Ghia had different alignment specs than the Beetle? I'm going to have to look that up...

IIRC, the Bentley manual had the Beetle Sedan AND Ghia both set at 3 degrees caster.

Hunter, the folks who provided the alignment racks, had the Sedan at 2 degrees and the Ghia at 4 degrees.  

I used to run my speedster at 4, but found it wandered a lot less between 5 and 7 degrees.  

My floor pan is a 72 Ghia and my book said 6 degrees. 6 degrees is working fine...Bruce

aircooled posted:

It took 6 degrees negative positive to get my car to act right over 60mph. It steers hard in parking lots lots now but I guess that's a trade off. I run 18 psi front and 22 in the rear. My car is higher in the rear to keep from draging on everything that's not level too.

Bruce

Fixed it for you.

Ps- As has been said, you need positive caster (more than stock for stability at freeway speeds and higher), and when you lower the front by any method involving the torsion bars (select a drop, beam adjusters, turning and welding the center section(s), removing torsion leaves) you change the angle of the trailing arms relative to the ground and reduce caster, as you're now steering more on the front of the tires. Shorter tires and offset spindles also reduce caster (although not nearly as much) as they tilt the top of the beam forward slightly (which reduces caster) as well, and the alignment will need to be checked.

Any time you change the ride height (front or rear) the alignment needs to be checked to be safe! As Gordon said, invest in at least a couple pairs of shims (and some longer bolts), as the shop will not have what you need. You can always sell what's leftover once it's done. 

Yoda out (for now, but back you know I will be!)

"You can always sell what's leftover once it's done. "

Or just keep them in your "just in case" bin full to overflowing with really useful stuff you'll probably never use again.  

Like me!

JEEZ.....Thanks Al....Can you imagine what 6 negative would be like to drive ? 

I was just thinking that some of you may think this caster stuff is over your head but it's one of the easiest to understand.  I hope this helps a little. Look at a bicycle. Also the "casters" on a movers trolley is another example.  Both are positive caster.      Viewed from the side, draw an imaginary line down thru the center-line of the the bicycle fork pivot and the trolley caster pivot mount to where it would touch the ground....mentally fix that point of contact on the ground. Now draw an imaginary line down from the wheel's center to the ground. It will be obvious that the point of contact with the ground for both the trolley pivot and the bicycle fork pivot are in front of the wheel's center-line contact with the ground...Hark, Hark !    Positive caster !

If the pivot line contacts the ground behind the center-line of the wheel's center it is Negative Caster.

Caster is a GOOD Thing  If you watch those "casters" on a movers trolley they always swivel around depending on what direction you wish to push it.  They always FOLLOW that direction of movement ! That is the effect of Positive Caster. Negative caster is what the trolley caster was in before it started to swivel around to follow the direction of movement. This is why we like to have positive caster (the wheel center-line is trailing behind the wheel pivot center-line (read ball joint/link-pin here). This tends to keep the wheels straight ahead while in a forward motion.          The weight of the car on top of those front wheels also helps to keep them in a straight ahead position as well. This is why a car with positive caster may be harder to steer while stopped or slowly rolling. You can actually see the effects of this while parked by turning the steering wheel from the center position to the right (or left) and watch the front of your car raise up slightly.  Technically, you are lifting the front of your car with the steering system.

Last example: When turning a corner, many of us almost let go of the steering wheel and allow the car to bring itself back to a straight-ahead position. This is the direct effect of positive caster with the help of the cars forward motion and the weight over the front wheels.....How's that for Steering Geometry 101 ?      Al...I think I got this right but correct me if I screwed up again please.........Bruce

Reminds me of when my dad would see a big girl on the back of a motorcycle. "Bet he had to turn the shocks up for her..."  I imagine passenger geometry factors in as well. "You're throwing off my caster b^tch!"

can you elaborate on this part of your setup some more:

 

"Currently: stock shocks; new stock steering box; lowered via torsion bar; new stock damper, ball joints and tie rod ends.  Shop alignment is "close" but could be better."

"Al...I think I got this right but correct me if I screwed up again please...

You explained it better than I could, Bruce.

To be more specific:  the front is lowered via adjusters added to the front beam.  The steering box is a trw replacement and i'm running 165/80r tires.   

Pretty much the same as my suspension, except for the wimpy tires   

I've lowered mine via AVIS adjusters (both top and bottom tube) and I'm running an adjusted TRW steering box.  With the wheels straight, I get about 1" - 1-1/4" movement back and forth at the top of the steering wheel.  

I've heard from some people that running drop spindles, rather than rotating the torsion bar anchors to re-set the chassis height, eliminates the potential for "bump steer", but I've not personally seen this - they're both about equal as far as I've driven both.

All good info, but it doesn't affect your alignment's "bump steer".  

Caster, caster, caster........  It will make it so much better, you'll think it's magic.  

I have a tire rumble around 70mph, so I typically run slightly over 75-ish mph, above the "rumble zone".  That "-ish" might include 80-ish, but it's a KPH tach, so how do I know?     At those speeds, my Speedster is pretty much rock-steady with around 6-1/2 degrees of Caster and around town the steering feels right - just like a car with no power steering (remember those? )

Caster, dude......   caster, caster........

i wholeheartedly agree with Gordon. 

i have air suspension so i can change the caster on the fly (think nose down / ass up and vise-versa) and i can reeeeealy feel the changes in caster.  it's honestly to the point of when i cruise on the highway, i change the caster to make it more stable (it doesn't take much).  

i bet you'll be surprised with the caster shims (which i also run BTW)

Oh, Great.....

Now I want air suspension, too.

 ^ I can't think of a single person who doesn't want a car just like Paul's. 

oh stop

 

(ok - keep going)

Paul your ride looks fantastic.