I know this matter has been brought up before, but all the threads on the topic seem to be pretty old, and I'm sure this is an issue that lots of teams face.

I'm looking into the shock absorbers for our 2009 FSAE car. Our 08 car (#83 at MIS) used Fox DHX3's which we had revalved with a custom shock curve courtesy of Push Industries. The shock was adjustable in rebound, and had sleeve bearings in the eyes.

We didn't have too much testing time with the car, but it behaved adequately at competition. With the exception being the left rear shock scooting off of the sleeve bearing and making friends with the bellcrank due to some misalignment.

The basic dilemma is this. The Fox's were hilariously cheap; I think in all it was <$1500 to get the shocks on our car after revalving. But this year I'd rather get something with sphericals in the eyes and more options to adjust it on the track, without bleeding money.

I've been looking into the Double Barrel, and it is somewhat expensive. But that is potential route #1. The other option is to sacrifice adjustability and go with quarter midget units.

I'm looking for input from anyone; teams that have used one or the other, teams in the same position I'm in now, design and cost judges who will grill me in a year's time. If you were the designer, would you save the money or go for the adjustability?

-Arjun Roy
Columbia University FSAE

We used Fox Vanilla RC's back in the day, and had them redone by Push. We liked them because they were cost effective, and worked. They were also pretty simple rebound/compression adjustable with no pro-pedal or any other stuff that would be fitting for a MTB but not racecar. When we were looking at Fox shocks again it seemed there was nothing that was just a R & C adjustable damper, and they had all sorts of extra crap on em. Push coulda taken that out, but then the price goes up and starts getting close to the more expensive dampers.

After that we tried the Risse Racing dampers.. and that was a disaster. They leaked as soon as you took them out of the box.. adjustment knobs would literally fall out when you were driving.. and it seemed like you could make lots of clicks of adjustment without any change to the feel of the car.

The Cane Creeks are pricey at $550 each (I think?) but they rock. The build quality is fantastic, they come dyno'd with plots for each damper, and have a very wide range of adjustment. When you make a few clicks of adjustment you notice it and can change how the car behaves.

Can't speak for anything else.

If you know very well what range of damping you want to be in, then you can get something with limited adjustability and make it work through motion ratio or what have you. If you don't know how many lbf/in/s you want all around, the big adjustability is nice!!

If you don't have linear pots and aren't going to be using data aq to set your dampers anyways, I would advocate making a spreadsheet with very accurate values for your spring rates (tire and suspension) and vehicle weight and weight distribution and specifying fixed valving Penske quarter midget dampers. They work very well and are inexpensive ($199) and are robust.

Naake (http://www.naake.com/) has treated us well and when you buy them they get valved to what you specify.

Matt

By far the cheapest available decent dampers in the 10" ish center to center distance range are penske quarter midget dampers. It ends up costing 250 per corner(200 a damper and 50 per spring). They have Aurora Com-5 bearings in each end and work with Eibach 5" free length springs. They also provide you with damper curves for your specific unit on request. They also have a full shim/rebuild kit for the whole deal. I believe we spent 2500 for absolutely everything including a nitrogen valve regulator and it all comes in a nice nice yellow organizer box. Contact Anita at http://www.indyms.com/ Also you arent sacrificing much in terms of major adjustability by going with them. You'll have to open them up and change the shim stack but if you do your homework right you shouldnt need to do it that often.

She is a very nice lady who is extremely responsive to your needs.

I vote against the Cane Creeks. They are way too stiff for a car with a decent motion ratio. If you can modify them, then they might work OK.

I do have to admit to get them to work we had to use a 1.7 MR or so.

Also I have a highly accurate model of those penske midget shocks in solidworks 07 that is a flexible assembly with the com-5 bearings in them and a "LimitDistance" contraint on it. Should probably get that uploaded to the CAD link. That and all sorts of stuff.

Thanks for all the helpful responses.

How easy is it to revalve the shocks yourself? And is it worth doing or feasible to do so when you do not have easy access to a shock dyno?

(If we did have easy and quick access to one, I'd have no qualms about getting three midgets for the price of each double barrel and play around with them like that.)

It's a pity the Vanillas were discontinued. With spherical bearings and some revalving work they'd have been ideal, I feel...

quote:

Originally posted by exFSAE:
I do have to admit to get them to work we had to use a 1.7 MR or so.

Was that for the Cane Creeks? We're yet to dyno ours...

Yes, that was for the CC's. All of ours came with dyno plots already done.. I had wanted something on the order of 8 lb/in/s I think at the wheel.. and the softest the CC would go was 25 lb/in/s. That's if I remember right.

That said, that MR worked real well for both damper rate and spring selection, and our suspension had pretty low mechanical hysteresis. Judges liked it.

So on a related note, anyone know anything about the Fox Podium X? It looks like a motocross shock, wonder how big it is...

It's especially interesting since there seems to be a 3-way adjustable version, but then it costs as much as the Double Barrel.

quote:

It's a pity the Vanillas were discontinued. With spherical bearings and some revalving work they'd have been ideal, I feel...

They were discontinued temporarily while the DHX line was phased in. Last season they started carrying the Vanilla equivalent as an entry level shock called the VAN R. It's the same frame, oil capacity etc., as the DHX line, but does not come with ProPedal or Bottom-out resistance, but is only low speed rebound adjustable.

Our Solar Car guys are using a pair of DHX 5.0's on the front of their car this year, and I gotta say that they are beautifully made. Our Risse's are cost effective, but they leaked out of the box too, and I second the observation that the adjustments didn't feel very different on the car. Motion ratios are something like 0.88:1.

The Delft guys had Risse J7's on their car at East this year, didn't really get a chance to talk with their guys what they had to do to them though. I am considering using the 7's and trying to re-do the valving in house, if for nothing other than the reasoning for using the Penske Q-midget dampers, you can buy 6 and mess with them for what you'd pay for an axle set of CC's.

Best,
Drew

We haven't used Fox Shocks in years so this might be a little out of date, but when we dyno'd the Fox Shocks we found that any 2 of them would produce significantly different characteristics. The advantage of the Cane Creeks was how consistent they were through out the entire range of adjustment. Also, Cane Creek has wonderful customer support. We had to send 1 of shocks back because it was leaking and it was returned to us within a week and didn't have a problem after that.

The Cane Creeks do have a huge range of adjustment, which is nice if you don't know how to design a suspension We put them on and only used a small portion of their range during testing because small adjustments made big differences.

Keep in mind that, for Design Competition, the team must have determined the requirement for damping forces. As with any element of design or construction, work 'contracted out' may result in a deduction of points.

Anyone planning/considering using the replacement for the Vanilla RC's , the Fox Shox VAN R's?

Side note: In regards to Risse shocks. They were really big on the mountain bike scene in the late 90's but then quickly died out within a few years because they were failing in competitions and picked up a bad rep. From my experience with them (on the mtn bike racing side) they we're crap compared to Marzocchi/Fox/RockShox

Hi all,


quote:
The Delft guys had Risse J7's on their car at East this year, didn't really get a chance to talk with their guys what they had to do to them though. I am considering using the 7's and trying to re-do the valving in house, if for nothing other than the reasoning for using the Penske Q-midget dampers, you can buy 6 and mess with them for what you'd pay for an axle set of CC's.


You're right, we used Jupiter 7R's on the DUT07 car competing in FSUK 2007 FSG 2007 and FSAE 2008. The DUT04 also had Risse shocks.
I'm sorry for the guys at Risse if they read this but here it goes:
- They were leaky as hell, Left Rear is completely depleted, the rest just runs out through all the adjuster knobs
- They feel extremely inconsistent wrt each others
- The adjuster knobs fall out, don't click some times or get stuck.
- The eyelets were machined incorrectly (too short) at first, however they did fix this for free.
- They are less expensive then DB's but price/quality is way worse.

I could go on but it wouldn't be good for the heart

Maybe we just had bad luck, but I've heard it from older team members too, and other teams. I'd suggest not using Risses at all.

The new DUT08 car has CC DB's, I could not attend too much of testing, but from what I heard no probs so far, and the build quality looks and feels great! They are expensive though.

Cheers,

Samo

We too have had some problems with our Risse shocks. Although, I personally would not be too quick to jump to conclusions about their quality due to our lack of experience. During design judging at FSAE VIR, our suspension judge jumped on the left rear of our car, and the right rear compressed more. Could be friction in our bellcranks, could be the shocks. We did notice that they had almost no pressure in them when we got home, though.

Just on a side note, we bought the 4 sets of springs to suit the Cane Creeks available from Motorsports Spares International, and they arrived here the other day.

From initial tests in our spring tester, the rates are pretty damn accurate and very close to their claimed rates.

Ridiculous value for money for a box of springs....

quote:

Originally posted by Chris Lane:
Just on a side note, we bought the 4 sets of springs to suit the Cane Creeks available from Motorsports Spares International, and they arrived here the other day.

From initial tests in our spring tester, the rates are pretty damn accurate and very close to their claimed rates.

Ridiculous value for money for a box of springs....

I am just curious as to how much you spent on those springs. We had custom spring made too and it was $230 for all 4.

We got the springs that come with the CC's stock.

4 full sets at 4 different rates = 16 springs

Let's just say that it cost us more to have them air freighted via FedEx here than the actual cost of the springs.

Dirt cheap.

I can say that our sixteen springs costs us less than you paid for four custom springs.