Pull Rod w/ top mount steering?

[ReadySetGo]

Just wondering if anyone is planning on top mount steering with a pull rod set up. I want to implement this on the new car, but it seems like there are a lot of forces applied to the top of the upright. For example, in a counterclockwise skidpad test, the frontright upright would experience upward, and steering forces.

I know it can be done,but is it a viable solution to top mount steering. The reason for the design change is that our bottom mount steering has 3 links between steering wheel and rack!

So if anyone wants to share any pics or comments please do.

thanks in advance!

[ReadySetGo]

Just wondering if anyone is planning on top mount steering with a pull rod set up. I want to implement this on the new car, but it seems like there are a lot of forces applied to the top of the upright. For example, in a counterclockwise skidpad test, the frontright upright would experience upward, and steering forces.

I know it can be done,but is it a viable solution to top mount steering. The reason for the design change is that our bottom mount steering has 3 links between steering wheel and rack!

So if anyone wants to share any pics or comments please do.

thanks in advance!

[Denny Trimble]

We've done it, no problems! (http://students.washington.edu/dennyt/fsae/a-arm_failure/pages/DSCF0009.html)

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

[drivetrainUW-Platt]

Denny,
you guys need to find a better tubing bender, that one is doin a pretty crude job!!

[ReadySetGo]

R.I.P. poor A-arm.... http://fsae.com/groupee_common/emoticons/icon_confused.gif I think thats what I don't want to do. What was the cause of the failure?

[Denny Trimble]

This is from our '03 car last summer, see the link below. Basically the braking loads on the lower ball joint caused the a-arm tube to fail where the rodend threaded insert was welded into the tube. Then, the brake stopped the wheel, and the inertia twisted the whole thing up. Sweet! So, the lesson is, 5/8 x .035 4130 tubing (heat treated) with about a 2" moment arm from the applied force on the rodend, is not sufficient for ~150 hours of driving.

Here's the link (http://fsae.com/eve/forums?a=tpc&s=763607348&f=125607348&m=7226097154&r=7226097154#7226097154), the pictures have been moved but you can find them above.

[BeaverGuy]

We were just talking about that failure at tonights meeting. http://fsae.com/groupee_common/emoticons/icon_wink.gif We were explaining the redesign of the a-arm to upright interface to a sophmore.

[jack]

one of our old cars (V26) has that setup, and has many, many hours on it and it hasn't failed. its not particularly overbuilt either.

...come to think of it, our 2004 car has that too, and lots of other stuff failed, before that even had a chance...

[V2 - Italy]

Our 2004 car is pull actuated with steering on top.

Here some pics:
http://www.pcm.unifi.it/FORMULA_STUDENT/ITA/Race_04.htm

If you need more detailed pics let us know.

V2