Rally Suspension project

[Crazyswede]

Wonder if there is enough room/clearance on the lower A arm and hub/tire to run a second shock on the front of the A arm. **** Probably cheaper to spend a little more on a set of remote reservoir shocks

the hydraulic bump stops are what a lot of the desert race trucks and buggies run. They have a small amount of travel and are there to help soften the big hits that bottom out the suspension...help soften the last bit of travel instead of a complete solid on solid. I think they are pretty pricy.

https://www.fourwheeler.com/how-to/susp ... ump-stops/

[Rallyho]

At $200ish/shock, a single bigboy shock would be cheaper. Anyone know the compressed and extended length of oem fr a rr shocks?

[Rallyho]

https://www.summitracing.com/parts/bsn-25-187878

Something like this would almost be a direct fit for the rear and if the fr top mount gets moved up a bit, could add an inch of travel there. Unsure about the valving....380/60.

[Rallyho]

And, FWIW, ShockWarehouse claims that KYBs for C900's measure in at:

Front 14.25/9.25in
Rear 17.87/11.69in

[KPAero]

I'll need to remember to come back later with more details. But I've looked enough recently to say for sure that the bump is first limited by the tire hitting the wheel well and would be closely followed by the lower arm crunching into the body, and the droop is limited by the upper A-arm hitting the body. Axle has enough room to support more travel, and thanks to the good quality OEM joints, Id expect those would be fine as well.

Not sure I feel like the hydraulic bump stops are worth it. The springs I ran at NEFR were good to start, but I lost ~1" of ground clearance as my lower spring perch I made slowly collapsed over the weekend. They were an Eibach that were a little stiffer than an SPG spring I think. I can find the specs later...

[KPAero]

And those 5100 series Bilsteins worked well on the back of some Fiesters

[Crazyswede]

I think luke modified the metal under the upper a arm to allow for more droop. I also remember at one point he had limiting straps on the a arms...but I dot remember which iteration that was.

[Rallyho]

Yeah, we've blown through the sheet metal on one side and scabbed in some angle iron at one point. Has anyone cycled the suspension while watching the tripod move in the inner driver? Our inner driver failure in 2018 was a strange one...we hit a big embedded rock on the left side while landing a jump at the bottom of a compression. It's unclear if the tripod "bottomed" out in the driver, tore through the sheetmetal wrapper or what....

[Crazyswede]

I remember geoff had his driver side inner cv pop out of the inner driver during a rally cross years ago at Okemo. It was a combination of lots of power during a full lock turn and suspension compression. Needless to say it made a mess and made for a long afternoon and evening to get a tow and fix it etc.

The passenger side drive shaft is longer iirc and should follow a longer arc through the travel. Also neither side driveshaft matches the arcs of the A arms. The error is made up by the slippage in the tripod and the driver. Very likely those extreme tripod failures are due to stack up error of compression and turning that stock cars never see

[Rallyho]

Pascal, you wouldn't happen to know the spring rate and damper valving for them there Fiesters, wouldya?

[Rallyho]

ooooh, look what I found. Anyone want to take a crack a throwing some numbers in?
http://www.usrallyteam.com/content/tech ... ulator.xls

[Rallyho]

The plan for this weekend is to do some measuring on the car and a bit of headscratching. Hopefully can get some corner weights, shock lengths, spring rate calcs (still don't have a spring rate tool), full droop & compression and see when/if the tripods pull out of the inner drivers. I'll also try and get some angles of ball joints...not sure what the limits are there.

[Crazyswede]

You can make a spring rate tool pretty simply. Just need a lever, some weights or a strain gage and a ruler or measuring tape

[Rallyho]

...rummaging through kitchen junk drawer for a strain gauge...

[Crazyswede]

If you have some weights for a gym set you could hang them off a lever arm and just record the spring deflection.it’s crude but should be close enough.