Dampers

[ftc_elvis]

Just wondering what types of dampers people are using. I'm looking into Penske's 8760 series and was wondering if anyone else has run these.

[ftc_elvis]

Just wondering what types of dampers people are using. I'm looking into Penske's 8760 series and was wondering if anyone else has run these.

[Big Daddy]

I have heard they were really nice but the price is way up there compared to you typical Fox or Risse shock. Plus the bike shocks seem to do the trick I would just dyno them to make sure they all are about the same in damping.

"A woman is a lot like a beer, they look good, smell good, and you would run over your own mother to get one." Homer Simpson

Nobody is born with a steering wheel or a gear shift in his hand. It's something you choose to do or you don't.
Mario Andretti (1977)

[steve d.]

rear motorcycle dampers are a curiosity...

500lb springs, 22 way adjustment on both compression and rebound, and you can get stock 'busa ones on ebay all day long for 30 bucks...

I'm gonna try them on the D-mod car and see what happens. (1150 lbs)

sjd

[Mi_Ko]

Does anyone use Penske, Ohlins or Biltein? (Or any other high performance racing damper?) Are they worth the extra money in comparisement to FOX.

I have a very hard work to do - to find some good dampers. (Why hard? Because I can't get them in our country and because they have to be cheap!) What should I look for?

Can anyone recommend me some good dampers?

2002/03 University of MARIBOR - Team Member

[steve d.]

you want cheap or good?? Like I said, I'm experimenting with street motorcycle rears. I'm sure off road motorcycle rears might work well too...

Motorcycle rear dampers would work great on an SAE car. I'm sure there are motorcycles in Maribor?

The tradition was to run mountain bike shocks for a while.

You will never EVER find Ohlins cheap.

steve
Y2K cadillac LMP shock guy

[Akos]

Lot of people think there are magical dampers that will make a car handle.

Generally speaking, I'm talking about monotube dampers, all shocks can be made to work and are pretty much the same. There are some piston designs, thus some velocy/force profiles, that you can't find in some shock.

For Formula SAE usage you would be looking for a digresive/digresive profile, which is easy to do even with a simple piston profile, so this isn't the problem.

Usually what you pay for is consitency between ïdentically" valved units, as well as low sticktion with good racing shocks.

Usually if you take your standard mountain bike shock, and just rebuild it with quality shim stack material you get a pretty good set of balanced shocks. You can usually machine the piston profile a bit to add pre-load to the shim stack to make it adjustable even with a light stack. Most mountainbike shock come with too heavey of a stack especially on the rebound side (the RCR twin tubes don't even have a high speed rebound circuit).

Once you figure out what you actually need from your shocks, its quite easy to rebuild a mountain bike shock to do the job well.


I would stay away from motorcycle rear shocks. They normally run a fairly high motion ratio. It would be overdamped if you install them on a reasonable bell crank setup with 1:1 motion ratio.

Cheers,

Akos

[steve d.]

I'll be sure to post my findings when I get them run on a dyno.

How high is the motion ratio?? let's use an R1 as an example. run of the mill 1000 cc street bike.

the wheel pretty much moves 3 times the bellcrank pivot (hence the VERY stiff spring) The bell crank has a 1.4 to 1 ratio in favor of the damper/spring. it's fixed to the chassis on the pushrod side of the bellcrank if everything moves optimally, the rear wheel goes up an inch, the pivot goes up .3. The entire bellcrank wants to go up as well, but one end is fixed. so that .3 inches is multiplied by 1.4 to get .4 inches of shock travel on 1 inch of wheel travel. so 2.5 inches of wheel for an inch of shock travel....sounds about right. if it's a 500 lb spring, so a 200 lb rider will compress the suspension enough to put it pretty close to the middle of the shock range.

Everything get MUCH more complicated when things stop acting at really nice 90 degree angles...

Those rear shocks only have about 3 inches of travel in them. (actually 2 before they hit the bumpstop.)

it's all about learning right? Please aruge if I'm wrong http://fsae.com/groupee_common/emoticons/icon_wink.gif

take a look at this one...it's a pretty good side shot. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=35592&item=2440020005

sjd

[This message was edited by steve d. on November 04, 2003 at 09:10 PM.]

[This message was edited by steve d. on November 04, 2003 at 09:20 PM.]

[steve d.]

taking a quick run through with my numbers, I should be getting just over 1/2 an inch of shock travel to 1 inch of wheel movement. mostly due to the pushrod angle...that's at 1:1. if I go 1.4: 1 in favor of the shock I'll pick up an extra 1/8" of travel...

yeah yeah...then I'll have to play with the rates...

sjd

[clausen]

Looking forward to hearing about your dyno results steve d

Regards

Paul Clausen
Uni of Adelaide