Dual Ride Height Adjusters?

[Matt Clark]

I've seen the dual ride height adjusters on a couple cars now, and the explanation I was given once of being able to independently adjust each side makes sense, but they also said it probably just makes whole setup more complicated for the average racer.

I guess I am curious as to what the rest of the FV world thinks of them. Are they worthwhile on a beam-type suspension? I have a beam I will be adding adjustment to, and am thinking about doing 2 on the top while I'm at it.

Also, of the 2 styles of adjusters, what do you recommend & why? I only have experience with the serrated/straight knurl, and I know it can't really be adjusted without disassembling the front end to relieve tension before breaking the adjuster loose. The other type looks to be easier to work with.

Thanks!

[Tiago Santos]

I would think it's more about increasing the spring rate than separate adjustment side to side

On some cars, it's hard to fit the adjuster in the center of the beam (interference with steering box, master cylinders, etc..) so this solves that problem..

I'm unsure about whether or not it would be a performance advantage.. Pros and cons, I guess!

[budawe]

To be done completely, the dual adjuster approach requires that the spring be cut into two separate sections. The idea is to be able to adjust corner weights. Frankly, with a zero roll rear end, I'm hard pressed to think this is needed since the cars tend to equalize themselves. The most I've ever seen in my cars is 5 to 10 lbs and that's more due to suspension friction rolling onto the scales than anything else.

I've used both styles and would prefer the serrated style to handle the weight of street cars but would go either way on a vee. The weight of the car holds the sliding assembly against the adjusting screws either way.

[sracing]

Brian is right. It is typically used for corner weighting. Not really needed on a zero roll vee unless you have something really wrong somewhere else. Also Tiago points out that it may be needed on those cars that have an interference issue in the center of the beam.

[Tiago Santos]

By using the two adjusters, with the same spring pack, you can increase the spring rate by 20% or so.. That could help with a couple of things, but it is a significant change to the setup..

I really think that would be the whole point of it, rather than corner weights. It's a vee, damn it, nothing in our cars is accurate to within 1/8" of an inch! And if it is at the start of the race, it won't be at the end anyway :P

[jpetillo]

I use dual adjusters solely because of interference. If your rear suspension is truly zero roll resistance, then the dual adjusters won't change the corner weights in any measurable way within the range of adjustability. John

[Bob Posner]

A few years ago Jess Heitman put Alan Harrington's Protoform P3 on the scales and found he could move upwards of 25# of corner weight around with the adjusters. Alan swore the handling improved.

[jpetillo]

That's because our cars are not truly zero roll resistance in the rear.

[Matt Clark]

Hmm. Interesting information guys. Thanks.

I knew being able to adjust them independently would allow different spring rates between the front wheels (that amount sounds debatable), but didn't think about separate springs or not. It makes sense that a cut spring is more independent, and I would assume a non-cut spring would add spring rate because there is less distance for the spring to twist in. Sounds like a good way to add rate without raising ride height?

Aside from clearance issues, it seems like it may help certain cars more than others. I don't think I will bother with it, but I could see where some simpler track layouts might show more of a difference. I'm thinking that Lime Rock or the Glen short course could benefit some.

[Mark Filip]

I don't think the rules allow you to cut the spring and make it independant side to side.

[jpetillo]

Mark, that's a good point to raise.

Matt, I wasn't certain what you meant, so let me add the following: The only reason you'd get a higher spring rate with two adjusters is because the adjusters are separated. So the distance from each adjuster to the end of the spring is shorter, giving the higher spring rate. Aside from that, the separate adjusters just change the ride height on each side, separately, but the adjusters do not adjust rates. Whether you cut the spring in the middle or not will probably have only a small effect on the final spring rate - the location of the adjuster will be main effect. I hope what I said makes sense. John

[Matt Clark]

Yea, that's pretty much what I meant, except I mis-spoke when I said about allowing different spring rates. I meant corner weights.... I had the right idea in my head, just used the wrong terms as I was reading & typing.

[BLS]

Since I just finished up a front beam with dual adjusters, a picture. I added the dual for two reasons. First, on a Citation it is difficult to have one in the center due to the steering gear location. Second, with a 3.5" spacing from the center, the front spring rate should increase about 20%. I liked a very stiff suspension when I last drove a car (30+ years ago), maybe I'll find I don't like it as much now...

[DaveB]

It is not hard to build a offset adjuster to install in a beam. Who says the adjusting mechanism needs to be in the center of the car, just the spring holding portion.

Dave

[Bob Posner]

Regarding the short dual spring length on the Citation,I'd suggest making up several spring packs of various leaf quantities. I found 6 leaves way too stiff and have 5 in now,and have a 4 leaf to try if needed. With the adjusters far out from the beam center the short springs really stiffen. Weld a small bolt to the end of the spring protruding through the turkey leg and the changing is easy - pull one out,shove one in,tighten grubs.

[jpetillo]

Yea, that's pretty much what I meant, except I mis-spoke when I said about allowing different spring rates. I meant corner weights.... I had the right idea in my head, just used the wrong terms as I was reading & typing.

That's what I figured.