Author Topic: Steering arms  (Read 330 times)

Online Paul New

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Steering arms
« on: July 19, 2018, 07:21:51 PM »
I am setting up a new front half on a car and I run 3 6 arms on my car but am looking at using a bellcrank on this one.  I have 2 6 arms for the spindles but am only able to find 5 C-C bell cranks is this going to make the steering a little to quick?

Offline dusterdave173

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Re: Steering arms
« Reply #1 on: July 19, 2018, 07:30:48 PM »
I watched videos of my first driving--I could see it was easier to slow down the steering than work on my instincts   A longer top arm did the trick--now I can drive it like a dirt tracker but it is so slow that it all works out
Another member here made one for me as we could not find what i wanted but I would call Neil & Parks they can do anything and it looks like jewelry
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Offline rooman

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Re: Steering arms
« Reply #2 on: July 23, 2018, 05:18:51 AM »
If you are connecting the drag link to the left spindle the length of the arms that connect to spindles to each other has absolutely no effect on the steering ratio but using a bell crank does make a difference. I have not built a car with a bell crank for a long time for a couple of reasons.
 First, although the wheels are generally pointed straight ahead on the track (or should be) and thus ackerman geometry is not an issue things get different when moving the car around the pits or the shop. A single tie rod is pretty simple while the fact that the bell crank swings in an arc makes the placement of the inner tie rod ends a little more complicated. Using a bell crank to steer to one wheel and then running a regular tie rod is a better idea and pretty much mandatory with front suspension.
 Second, there are just more parts in a bell crank set up. An extra pair of rod ends, the bell crank itself (including the pivot and its mount).
 At one time long ago when 30 plus degrees of caster was the norm the bell crank package helped as it makes it easier to rotate the spindle on the king pin compared with trying to push the spindle down on the end of the axle due to the big caster number. Don Long cars all steered with the drag link to the spindle and all big show funny cars are that way as well now (and they used to run bell cranks) and if it is good enough for them it works for me.

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Online Paul New

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Re: Steering arms
« Reply #3 on: July 23, 2018, 09:07:49 PM »
Thanks for the info The only reason I was thinking of going with the bellcrank is just how clean the drag link looks going down the frame of the car

Offline PSweeney

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Re: Steering arms
« Reply #4 on: July 27, 2018, 06:50:47 AM »
I have a bellcrank for that very reason, I don't like long links coming off the idler.   Mine is laser cut from 3/8" stainless, is bronze bushed on the pivot and rides on a machined boss welded in to the chassis, with nylon shims above and below clamped up with an ally top cap.  The machined boss and ally top cap have recessed grooves to accept the nylon shim. The whole piece is machined such that the preload is bang on.   We did try a roller thrust bearing but it felt notchy.  If I were doing it again, I'd bore the bellcrank to accept a sealed ball bearing.  Overkill but cheap and easy to do.

I spent a lot of time drawing because 6" looked goofy.  I came to the conclusion that it's not really worth worrying about.  I have 6" arms and I locate the drag links directly too the bellcrank dogbone.  You want separate holes in the forward facing end to separate the rod ends.  The gap between those holes has an affect on Ackerman as each wheel is articulating around a different arc and therefore is in a different angular position relative to the other.  Draw it out if you're unsure. 

Online Paul New

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Re: Steering arms
« Reply #5 on: July 27, 2018, 08:55:58 AM »
Thanks appreciate the help information