Shocks: price vs. capability

[FATMOUSE]

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

[FATMOUSE]

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 &lt;$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

[exFSAE]

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!!

[Matt N]

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

[rjwoods77]

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.

[flavorPacket]

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.

[exFSAE]

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

[rjwoods77]

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.

[FATMOUSE]

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...

[Chris Lane]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by exFSAE:
I do have to admit to get them to work we had to use a 1.7 MR or so. </div></BLOCKQUOTE>

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

[exFSAE]

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.

[FATMOUSE]

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.

[Drew Price]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">It's a pity the Vanillas were discontinued. With spherical bearings and some revalving work they'd have been ideal, I feel... </div></BLOCKQUOTE>

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

[John Grego]

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 http://fsae.com/groupee_common/emoticons/icon_wink.gif We put them on and only used a small portion of their range during testing because small adjustments made big differences.

[scholar]

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.

[Spearchucker]

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

[Samo Simonian]

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 http://fsae.com/groupee_common/emoticons/icon_wink.gif

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

[Matthew Bell]

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.

[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....

[Corey H]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">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.... </div></BLOCKQUOTE>

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.

[Chris Lane]

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.

[Drew Price]

Samo,

Thanks very much for the insight, I guess I was hoping you guys had a better experience with them than most.

We had two leaky ones when we got out J3's, and the press-fit bores on two of them were actually slip fits. That being said, they did fix everything for free, they were easy to get hold of to get them fixed, and they came back promptly.

This summer I am planning on taking at least one apart to see if there is anything that I can do to get the internals at least a little more reliable, if not more consistent. There is an old Vanilla RC of the solar car team's laying around that the new captains might let me take apart too. There could still be some value in using them basically for cores so that if you are going to try to make your own dampers you at least don't have to make the bodies, shafts, perches and ends. They may even be able to be converted to a solid-piston design like the Ohlins stuff.

Best,
Drew

[Steve O]

I have to say that despite previous posts I have posted in regards to praising Risse, saying that we've had no problems with them, I must not recommend these shocks to anyone unless they straighten out their act.

Before, I felt compelled to talk them up because of their FSAE sponsorships they do; however, this year has been nothing but a headache for us. We decided to get new Risse shocks because our old ones were, well, OLD. We decided to go with the same models but with the remote reservoirs, the J5R's. At 50% off I felt we couldn't go wrong. Was told the shocks would be shipped in 2 weeks. Two weeks later, as anticipated, I got a shipping notice from them but the shocks never showed up. Apparently the shocks got stolen from there pickup location, which I can't blame them for. After another 3 weeks another set was made and sent our way. Got them to find that only 2 of them worked properly the others when compressed by hand sprayed oil out next to the compression adjustment knob. I called them up they said alright send them back. I paid 30 bucks to overnight them...no, even partial, reimbursement. Got them back again about a week later, one worked, the other one did the same thing still. I called them up and this time they sounded frustrated with me and claimed that they tested it. I said well if you tested it you obviously were blind to the oil spraying out everywhere. Again paid to overnight, got it back another week later with the same problem, sent it out one more time. Got it back and FINALLY it wasn't leaking oil; however, the compression adjustment had zero effect on it and the pressure in it was good so we, now running low on testing time (nearly 9 weeks after originally ordering the shocks) opted to match the compression damping with the adjustable shock to the non adjustable one and deal with the slightly sub-par performance since the other one was stuck only slightly softer than the adjustable one.

Now, we thought everything was good, boy were we wrong. If anyone was watching our skidpad at the west competition I am sure you saw it happen. In the drivers second run halfway through the circle you can see the shock blow out and the driver almost loose control, he regained control and finished the run...excellent driving on his part. We didn't think anything of it at the time and just thought he was getting loose until just after I took it for a spin on the practice track and in a left hand corner I felt the car roll significantly more than it should the body ate the ground and my left rear tire lifted off the ground a couple of inches. We looked under the car and sure enough the front right shock was covered in oil. This was one of the shocks that we thought was good from the beginning... guess they don't ever get it right on the first try. Anyway, we were lucky to have a couple of 550 springs which were stiff enough to compensate for the blown out shock. The car actually handled quite well with the 550's in front and down a shock but that was just luck.

Alright, thats my rant, and that is why we too will be looking for a different shock this year. It is unfortunate because we like the damping characteristics of our Risse's when they work right.

Steve

[Matthew Bell]

So if we wanted to look at moving to the Cane Creeks, does anybody have any contact information? Also, wondering where people get custom springs made. Thanks for your help!

[flavorPacket]

If you search here you'll find tons of great spring suppliers. The cane creeks are sold through Motorsports Spares in Indy. The phone # is on here somewhere.

[dazz]

Anyone used Avalanche Racing suspension? Probably a bit on the expensive side, however they do have a reputation for excellent quality & performance.
Link:
http://www.avalanchedownhillracing.com/products.html

[Spearchucker]

Avalanche is expensive, but they are used by professional mtn bike riders that do 30+ ft drops. They are some of the toughest available, no doubt.

[Scalesy]

yea steve o is right, we had nothing but problems with the risse shocks this year. maybe a bad batch or something because it seemed like a repeat occurance...nice shocks otherwise though

[Matthew Bell]

For an update on our Risse Shocks. We found out the hard way, during design judging, that the shocks were not pressurized properly. Our judge jumped on the right rear of the car and the left rear shock compressed more. When we made it back to our shop, I pumped them up and the car did not exhibit this characteristic. Also, we just got back from an autocross weekend with the formula car. We used the weekend to test car setup and adjusted the rebound and compression. Although the adjustment knobs only had small effects, they did help settle the car some.

[bahous]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by exFSAE:
I do have to admit to get them to work we had to use a 1.7 MR or so. </div></BLOCKQUOTE>

How did you come to this conclusion? Have you been using CCs for a couple of years and every year you changed your motion ratio?

Also, what ride frequency are you trying to achieve with a MR of 1.7? With my calculations, I need a 200lbf/in spring to do that

[exFSAE]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">How did you come to this conclusion? Have you been using CCs for a couple of years and every year you changed your motion ratio?

Also, what ride frequency are you trying to achieve with a MR of 1.7? With my calculations, I need a 200lbf/in spring to do that </div></BLOCKQUOTE>

Ride frequency was not my main concern doing a racecar suspension.. particularly for a super smooth track at Ford MPG.

We had the car's handling the year before tuned about where we wanted with ~250 lb/in springs (~85 lb/in wheel rate). There was some question as to the front end bottoming out with hot tires under hard braking.. and we (stupidly) assumed stiffer springs would just mean better handling.. so we eventually settled on 320 lb/in springs for final setup. They were stamped 300 lb/in, but they were all 320+. It kept the front end from bottoming and the rear drivetrain from overextending.

The next year, the reason we kept the 1.7 MR was mostly to accommodate the high damping rates. We could have gone to State an hour north and have them help us bleed and revalve the CC's for a softer rate, but I didn't want to chance F'in up my new expensive dampers.

For the right compromise of roll, pitch, and ride damping with the ~100 lb/in wheelrate we were carrying over, I figured about the softest I'd want to be able to tune the dampers would be about 8 lb/in/s at the wheels. I think the softest damper setting on the stock CC was about 24 lb/in/s, so that necessitated the 1.7MR.

The really stiff roll rate also provided for some good kinematic control, given that the tires we were using.. their cornering stiffness would drop like a brick as you added camber. At least that's what the data said.