Is it better to use dropped spindles or just an adjustable beam?
Some have mentioned that the adj. beam will give a stiffer ride, but I believe that's something I'll do anyways, right? So does it really matter then? Or does the rides geometry really suffer? And it's still better to go dropped spindles and then stiffen it?
thanks
Rip
dropping
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TeamEvil
- Posts: 227
- Joined: Tue Dec 02, 2003 3:32 pm
Drop spindles are a much better way to go. You can use stock length shocks so the choice is much greater, the front end geometry can be put right again with a single set of caser shims, and the ride is just as it was with the stock spindles.
If you're stiffening the ride you should only do it through shock choice or aftermarket torsion bars. Buy the forged spindles (not welded). And remember to buy longer mounting bolts when you get the caster shims.
Luck,
TC
If you're stiffening the ride you should only do it through shock choice or aftermarket torsion bars. Buy the forged spindles (not welded). And remember to buy longer mounting bolts when you get the caster shims.
Luck,
TC
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TeamEvil
- Posts: 227
- Joined: Tue Dec 02, 2003 3:32 pm
That's a good question. It would seem to cause a an imbalance within a nicely build system, almost forcing one set of torsion leaves to fight against the other. You might want to check here:
http://www.speedsterowners.com/
A lot of the lowered beams in the Speedster replicas have a single adjuster (on the top) and work well. These guys are a lot of fun and know their stuff and include a whole group that autocross quite a bit.
Luck,
TC
http://www.speedsterowners.com/
A lot of the lowered beams in the Speedster replicas have a single adjuster (on the top) and work well. These guys are a lot of fun and know their stuff and include a whole group that autocross quite a bit.
Luck,
TC
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Theo
- Posts: 478
- Joined: Thu Feb 19, 2004 4:49 pm
Re: dropping
I plan on doing both. Having adjusters in both beams allows setting the 'preload' and can realy tighten up the front. For lowering the droped spindles are the ticket.
Theo
Theo
Rip wrote:Is it better to use dropped spindles or just an adjustable beam?
Some have mentioned that the adj. beam will give a stiffer ride, but I believe that's something I'll do anyways, right? So does it really matter then? Or does the rides geometry really suffer? And it's still better to go dropped spindles and then stiffen it?
thanks
Rip
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Theo
- Posts: 478
- Joined: Thu Feb 19, 2004 4:49 pm
I don't know if it true but it seems to reduce bounce. A stock ball joint beam has some preload. I added a little extra using the adjusters. I read about this on a Brazilian road race web site.
I tested it when the beam was removed and with no preload I could easily move the spindle up and down. With the preload it was noticably stiffer.
If the spring rate on torsion leafs is progressive it makes sense the preload would change things. It they are linear it would seem to cancel out.
Theo
I tested it when the beam was removed and with no preload I could easily move the spindle up and down. With the preload it was noticably stiffer.
If the spring rate on torsion leafs is progressive it makes sense the preload would change things. It they are linear it would seem to cancel out.
Theo
Bill K. wrote:So, a dual adjuster beam can be preloaded? Set the upper low and the lower high to increase the spring rate? Net height change = zero? Sounds interesting if true. Please explain.
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Marc
- Moderator
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- Joined: Thu May 23, 2002 12:01 am
Theo's correct, by mounting the springs at a slightly different angle you preload one against the other which yields a progressive effect because the action of each stack is non-linear. VW played around with this over the years, going from 4° to 6° to 2½° of preload on the kingpin frontends alone.
At stock ride height the trailing-arm suspension "steps" over obstacles easily, as any bump that pushes back also makes the control arm swing up. The more you lower the front end the less of this effect there is - when taken to extreme so that the rest angle of the control arms is up towards the spindle, the spindle must move forward to go up. The result is a less-compliant suspension.
Another concern when lowering without drop-spindles is the travel available in the tierod ends (particularly the LH side ones) and the ball joints. Simply reversing the LH tierod usually eliminates that concern, but you still want to check that they'll never be max'ed out before the suspension travel is since one might snap. Even if the ball joints don't break, when they do suddenly max out a lot of force remains in the system that has to go somewhere - where it goes is into the inner-upper control arm bushings, destroying them.
I've got both drop-spindles and Avis adjusters on my bug with a single set of caster shims (I bought longer bolts but found the stock-length ones adequate with only ~5/16" of shim). Combined, this'll let me bring the front down to where there's only about an inch between the bottom of the shock towers and the ground (the only time that might ever happen would be for a car show, I wouldn't think of driving it like that). I expect to leave the adjusters at approximately stock height and run stock-length shocks, but I do have a set of the 2" shorter Opel GT shocks handy if I decide to slam it further.
At stock ride height the trailing-arm suspension "steps" over obstacles easily, as any bump that pushes back also makes the control arm swing up. The more you lower the front end the less of this effect there is - when taken to extreme so that the rest angle of the control arms is up towards the spindle, the spindle must move forward to go up. The result is a less-compliant suspension.
Another concern when lowering without drop-spindles is the travel available in the tierod ends (particularly the LH side ones) and the ball joints. Simply reversing the LH tierod usually eliminates that concern, but you still want to check that they'll never be max'ed out before the suspension travel is since one might snap. Even if the ball joints don't break, when they do suddenly max out a lot of force remains in the system that has to go somewhere - where it goes is into the inner-upper control arm bushings, destroying them.
I've got both drop-spindles and Avis adjusters on my bug with a single set of caster shims (I bought longer bolts but found the stock-length ones adequate with only ~5/16" of shim). Combined, this'll let me bring the front down to where there's only about an inch between the bottom of the shock towers and the ground (the only time that might ever happen would be for a car show, I wouldn't think of driving it like that). I expect to leave the adjusters at approximately stock height and run stock-length shocks, but I do have a set of the 2" shorter Opel GT shocks handy if I decide to slam it further.