Dampers

[D J Yates]

I've got a few dampers on my shopping list:

Penske 7000 series (rebound adjustment only)
Penske 7800 (no adjustment)
Ohlins ST44 (rebound and compression)
Ohlins 36H (not sure about this one... possibly rebound damping)

Has anyone run any of these dampers and what were your expereinces? Although i have no expereince of revalving a damper, i was assured that with the right tools and some practice it could be done out the back of a van (i.e at comp) in under 30 mins. This, plus a single rebound adjustment (for fine tuning between autocross runs etc) sounds ideal.

If i had the budget, i'd like to try some 3 or 4 way adjustable dampers. But at what point does the law of diminsihing returns come into effect. For FSAE, even if you had the money, is this level of adjustment going to give you any advantage? For that matter, do i need any adjustment at all?

So far i haven't mentioned mountain bike shocks. We used them last year and had no major problems. However, i've always wanted to move away from them, more so after the coments of a design judge regarding damper development in FSAE. The lack of technical support and the price gap compared to race dampers makes me sceptical about the quality. Does anyone have personal experience rebuilding them? Is it possible to get a MB shock to work to the same standard as the above dampers without further investment?

[Wayne Gross]

We have ran Ohlins ST44 the past few years. These dampers are 2-way adjustable. We have had great luck with them since switching over from Fox Shox and love them. You definetely get what you pay for. The are incredibly adjustable, and we can rebuild/revalve them in about 10-15 minutes each, using the tools kit that Ohlins sends with them. We deal through Motorsports Spares, they hook us up pretty well and are some cool guys to deal with. Check out www.motorsportsspares.com (http://www.motorsportsspares.com) or give them a call and ask for either Greg Hazard or Scott Besst.

[jack]

i have seen University of Washington, Cornell, RMIT, and several schools from down-under with the Penske 7800 dampers. we will hopefully be using them next year. i have no experience, but i would say they are a good choice.

also, did anyone else get that thing in the mail from Risse? how about those?

[Denny Trimble]

I don't think Cornell uses the Penskes, I think they use Tanners or customized versions thereof.

We tried tanners at first last year, they're RC-car simple. Not in a good way http://fsae.com/groupee_common/emoticons/icon_smile.gif

If you go with the penskes, order the shim kit and find access to a shock dyno. They come set up for four different corners of a 1/4 midget car, so they'll need some internal work.

[Jarrod]

we got hold of th 1/4 midget penskes last year, i sat down with a set of instructions, a new shim kit, and an hour later had two revalved dampers to my settings without ever having pulled a damper apart before. After a little practice i am sure you could do four in half an hour. Getting the air out of the oil is the tricky bit. Make sure you can get access to a shock dyno too, so you can put a few settings in and see what effect they have. I can't comment on how they work on the car as we didn't run due to unrelated issues. The quality of all of the parts is excellent though. We paid the same for our penskes as we do for a Fox RC. (I think the fox shocks are a little more expensive over here)

[Schumi_Jr]

Can anyone tell me what type of damer the Penske 7800 is? Is it a mono-tube or twin-tube or some wacky-kind like the Tanners.

[D J Yates]

The 7800 is a monotube damper. They don't appear on the Penske site, but when i phoned the UK supplier they were suggested, apparently they're popular amongst FSAE teams. The only downside is that there's no adjustment, other than that they sound ideal.

The main problem i'm going to have is convincing the team to give me the cash. Currently, were paying £100 per Fox shock. So whatever i go for it's going to be a big increase in cost.

Where do you get your Dyno's from? There was an aritcal on Dyno's in Race Car Eng recently, which got me thinking about the machines the uni technicians are dismantling for scrapping - loads of old hyrdaulic parts hanging around.

Wayne, what's the open length and travel on the ST44?

I'm not familar with the 1/4 midget stuff. Is the 7800 smaller than the rest of the 7000 series? At over a foot open length, they're just way to long for our car.

[Schumi_Jr]

We're lucky enough to be sponsored by Dynamic Suspensions (F1/CART/IRL supplier) so we have access to their dynos and engineers.

[Wayne Gross]

D J, the ST44's install length is around 9.25", with a total stroke of around 2.5", making the open length around 10.5". These are pretty close estimates, I'd have to go out and measure them to get an exact. Check out the ST44 owner's manual here for more info: http://www.ohlins.com/car_manuals.shtml We do our dyno work either with Rahal Racing, or with a automotive suspension supplier that I co-op with.

[ben]

The Birmingham team are using the Penske's this year. I saw the dyno curves the other day and the repeatability is to die for.

We ran Fox last year and I regret it bitterly. Beg, borrow, steal, etc.

Ben

[D J Yates]

Ben, are you refering to the 7800 Penskes?

Has anyone had any luck using differnt dampers for the front and rear? I'm not sure i'll be able to raise the cash for 4 ST44 dampers, but was thinking maybe 2 ST44 at the front and 2 36P at the rear, or something equivelent.

[ben]

Not sure of the PN. They're the red ones without any external adjustment and no remote res.

Ben

[USC]

For those of you running Ohlins ST 44s: What size springs are you using and where did you get them (custom wound?)

[Wray]

Originally posted by jack:
also, did anyone else get that thing in the mail from Risse? how about those?

Would you mind elaborating on this? We never got any info from Risse. Are they offering a discount or something?

Thanks,
Wray

[jack]

we got a "promo" type thing in the mail from them, i don't think anyone asked for it specifically. i'm sure they would send you one for free if you called them.

it was just info on the dampers that work for fsae. the prices were about the same as the competition, $200-$250 a damper.

[Mike Cook]

Originally posted by USC:
For those of you running Ohlins ST 44s: What size springs are you using and where did you get them (custom wound?)

We run Road Magnet springs. The company is based out of Baltimore. Our particular springs have a 6 inch free length and are about 1.8in ID. They were wound to our specified spring rate, and measure in at about +- 1% of our custom values. (All within 99.8 and 102.2 lb/in). In addition they also powder coated the springs. They charged us 65$ per spring Mark is the president of the company, and an all out nice guy. He stayed late with us to one evening to show us around their facility. Be sure to let him know that Mike and university of Maryland sent you. Their webaddress is http://www.roadmagnet.com/ and their phone number is 410-686-9100.