gtred

It seems that once you lower the car, you're working only with the last few inches of shock travel; much of this travel is on the bump stops.

Is there any advantage to lowering the lower shock mount in the control arm? It could be done pretty easily. Or, is the car happiest running on the bump stops in a hard turn?

Joe Perez

iTrader: (8)

Well, I'd certainly like to see it done.

The more conventional approach has historically been to use dampers with a shorter body (thus lowering the lower contact surface of the bumpstop) or to use upper mounts which raise the upper contact surface of the bumpstop. For '90-'97 cars, the '99 and later style upper mounts provide a small amount of extra travel, and then there are more extreme upper mounts such as those made by ISC Racing and Flyin' Miata which provide so much clearance at the top that one must be careful to limit travel in order to prevent binding of the suspension.






I don't have a lower control arm sitting here in front of me, but I'm having a hard time visualizing how you would lower the point at which the bottom of the damper attaches to it.

rleete

iTrader: (21)

ISC tophats work well. Not as nicely finished as the FM ones, but much cheaper. Anyone who can weld (I can't) could probably make them fairly easily.

Braineack

iTrader: (62)

you car will be happiest in CA.

RyanRaduechel

iTrader: (10)

Another approach would be to do what I did. I drilled the spot welds and torched out the rubber (or whatever it is filled with) in my stock 90 upper mounts, flipped them over and welded them to the top. Added some extra travel and it was free.

gtred

Thunderhill and Laguna are my favorite tracks!

I have a mildly lowered 2004 and have Bilstien Sports, but am still pretty close to the end of the "non-bumpstop" travel. Combine that with 400/275 street springs + sticky tires and it's pretty well riding the bumpstops on every turn at the track.

It's taken my entire seasons racing budget just to the car up to safety spec + all the details to get the car past tech... (everything from window nets to tow hooks)... so my street suspension has gotta work for this summer.

It looks like I can either run the car at a higher ride height than would be optimum (for camber adj, etc), or, it looks like I could lower the position of the thru bolt carrier at the lower control arm to get maybe 1/2" more travel with pretty minimal cutting/welding. A little work, yes; but zero cost.

Would it help to use the NA trick on the upper hat as shown?

Oscar

iTrader: (2)

I can get new NB topmounts for $50 a set, why bother with redesigning the lower control arm?

RyanRaduechel

iTrader: (10)

Before going into the lower control arms, which sounds like a pain in the ***. The uppers can be modified very easily for more travel. Why reinvent the wheel for this? I am with Joe on this and would definitely like to see it done, and see it done easily.

gtred

Here's what I must not understand about the top mount repositioning. It seems to me that the modification to the top mount will lengthen the rod (thereby keeping it from bottoming out from with-in the shock, but not change the relationship to the shock body and the top mount. Since it is the shock body that contacts the bumpstop, it seems that the top shock mount mod would not help to give you more suspension travel unless it also moved the top spring perch upwards.

Forgive me if I am not understanding this right. I'm Scandinavian.

EDIT: I see it now, the entire shock body goes up inside the extended shock mount!

1st race is this weekend and I've still got so much to work out!

Braineack

iTrader: (62)

the shock body does not move whatsoever, the shaft moves up.

this moves the pistons from being near the very bottom of the shock at rest, upward, towards the middle of the shock. which means it has more compression travel.




in this picture the only change is adding the extended tophat, but notice how much more travel you get?



now look, the shock never moves, nor the body, just the shaft.

rleete

iTrader: (21)

Picture fail, brain.

Joe Perez

iTrader: (8)

How embarrassing for Brainey.

Let's try this again, only with less fail:


The shock body does not move whatsoever, the shaft moves up.

This moves the pistons from being near the very bottom of the shock at rest, upward, towards the middle of the shock. Which means it has more compression travel.




In this picture the only change is adding the extended tophat, but notice how much more travel you get?



Now look, the shock never moves, nor the body, just the shaft.

richyvrlimited

iTrader: (1)

Joe, you don't magically gain more travel.

You gain more compression travel at the expense of droop, there's never a free lunch

Joe Perez

iTrader: (8)

I was just re-posting what Brainey put up, only with working images.

The OP started into all of this by asking about the amount of "free" suspension travel available with the car at rest and the suspension in a partially-compressed state. For a given shock length, you can increase that amount by either moving the body of the shock downwards (as the OP originally suggested), or the mounting point of the rod (and with it, the bumpstop) upwards. Either method will gain compression travel at the expense of droop travel, and by the same amount.

Braineack

iTrader: (62)

i said travel as in bump travel. whatever semantics.