Front shocks ?

[veefan]

I saw this picture on the web, I'm assuming it's an FST. Most of the FST's I've seen either use a modified shock tower system or a rocker style shock system. I think this style was also used on the committee car. Is this a good or bad design??



although I'm pretty sure mounting an MSD behind your head in an open wheeled car in the rain might let you do the uncle fester trick...

[Bill Bonow]

John,

We had mounted the shocks like that on the Committee Car. I don't think it's the best geometry. As the suspesion goes into bump, the shock keeps moving closer to horizontal and the motion or travel speed keeps decreasing . The best bet is to mount them straight up and down (much like VW did). Very direct motion and simple.

When we converted Gomez, we had a much better understanding of how to actuate the front shocks. The photo below shows simple outboard shocks hidden behind the shock tower. Reasonably clean and the car seemed to handle very well. The best part was we used the front shocks directly off the FV!

[jsteeb]

Good....Bad.... ?

IMHO - I would avoid it. Think of it like this... A shock has to move for it to work. In this arrangement, it's going to move very little compared to the wheel.

When I was planning out my Lynks, this setup had a very poor motion ratio for the damper - which got worse as the wheel traveled through jounce. This means a given shock has much less control over the unsprung weight. You will need more damping, and may have a harder time feeling small adjustments - among other issues.

Having said all of that... Grattan, 2010... Doug Seim trounced all of us even after the mounting brackets on his front shocks failed. Go figure...

Cheers.
Jason

[jsteeb]

BB always beats me to the punch!

I installed the shocks on the Lynks in the same way Bill mentions above.

[Bill Bonow]

I always get nervous when I'm up against a GM suspension engineer! At least we said the same general thing, don't mount the shocks as seen in the upper photo

[jsteeb]

HAHAHA... I've learned a lot about FST's from reading your posts and chatting you up. A Camaro they are not.

Besides - I'm just a design guy man. The development guys are the real smarties. Maybe one day....

[veefan]

Thanks Bill and Jason, I didn't realize how clean the FST installation would be without the towers. I figured the geometry might get all out of whack with the shock mounted like that on an angle in the picture I posted. The inboard shock mounting looks trick and might offer better aero, but trying to that installation right and working correctly seems impossible for the average guy.

Jason, I've seen some of your in-car video, your setup works perfectly!

[Bill Bonow]

Everyone likes inboard pushrod actuated shocks. Plenty of "schwing" factor

However, I think the reality is that the simplicity of outboard is hard to beat in regards to ease of conversion (FV to FST). I think I would argue pretty hard that the aero benefts of inboard, "schwing", is minimal (at best).

Outboard front shocks can be built to look good and function very well

[Jim Nash]

I have to agree with Bill. The "schwing" factor is big, and I think the only real benefit of an inboard shock arrangement vs. a well done outboard set up is crash damage. If you've damaged an inboard shock, you've had a hell of a shunt.

Given the race results of Jason and Doug S., it's tough to diss an outboard set-up.

Jim

[Diamond Level Motorsports]

My vote will be for outboard. Now, just have to find the right shock for the job.......

[Garry Sharp]

Speaking of the right shock for the job, I am redoing the front shock system on the Citation basically just like the Gomez. The thing is, my shock towers were cut off on a curve that is the same as the beam tube. It looks great and all but the back side of the tower is actually LOWER than the beam. I would like to keep the upper mount at the most even with the upper tube. What this means I would need a very short shock. I have seen some setups like this in some pictures from Europe. I thought I saw a picture somewhere of the LOWER mount extended down to give more travel.

Thanks,
Garry

[rgu]

Gary I would build the base up from the upright. When you weld on the beam tube itself at this position you can screw up the roller bearing inside. I'd also use the shock mount kit made of laser cut parts that SR sells. It lets you mount the shock anywhere you want. (Besides I made the original form for this piece from masonite so I have a vested interest.)

Don't hang a mount down. I've seem these break off with disastrous results. Check out Doug Seim's video from Blackhawk for evidence

[veefan]

About the shocks... I have a few sets of vee shocks but most have long bodies and do not appear to offer enough travel with the towers cut off. Any recommendations ?? Also what is the typical valving for an FST?

[Bill Bonow]

Now, just have to find the right shock for the job.......

This goes along with John's question. Can't say that a standard has been established on size or valving. Many have used lots of variations. None of them have been terrible.

We've been using ARS in Indy for our shocks on the Evolution and been very happy. Nice guys, easy to work with. I'd like to come up with some basics for an outboard shock so that converters can simply order part number X shocks and be in the general ball park. Need to work on that.

[rgu]

ARS shocks are good. We use them but they are a bit pricey. The two guys that came out last year in conversion cars both used PRO shocks. They seemed fine and had enough travel. Besides they are pretty cheap. Call Jim at SR I think he carries them.