FE-FC Holden Discussion Forum

Technical Board => Modification Help => Topic started by: NES304 on May 13, 2012, 07:23:52 PM



Title: What's the right length steering arms
Post by: NES304 on May 13, 2012, 07:23:52 PM
So I am running a HR front end with VT commodore rotors and 15"B45 Simmons, the question I have been researching and can't come to a decision on is what steering arms to run. I have heard that steering will be WAY too light with power steering so I have opted for the manual steer rack already, also heard that HR arms still make it feel "light". Also researched the use of HQ ones which are shorter and even shorter again the LC Torana ones.
Any advise on which way I can go with steer arms would be appreciated.
Cheers


Title: Re: What's the right length steering arms
Post by: mcl1959 on May 15, 2012, 09:00:10 PM
IMHO the HR steering arms will be fine

Ken


Title: Re: What's the right length steering arms
Post by: NES304 on May 16, 2012, 06:55:39 AM
Thanks Ken


Title: Re: What's the right length steering arms
Post by: fe350chev on June 06, 2013, 09:52:53 PM
If one was to need to buy new arms anyway, which HQ ones would be the go, the short power steer ones? The would decrease mechanical advantage and make steering feel heavier perhaps?


Title: Re: What's the right length steering arms
Post by: FC427 on June 06, 2013, 11:02:54 PM
I posted a picture of the 6 different Holden steering arms and am sure it had the length as well ,,, a while back but don't ask me where  ??? ??? ??? ??? might be worth a search if your interested ........FC427......


Title: Re: What's the right length steering arms
Post by: Ole on June 07, 2013, 08:21:02 AM
NES I was using a rear mounted manual commodore rack as well and used HT steering arms. They are midway in length between HR & HQ and were just right for my application.

Regards Ole.


Title: Re: What's the right length steering arms
Post by: 87 velo on June 07, 2013, 11:00:03 AM
Anyone checking the toe out on turns? Using steering arms from models with a different wheel base may an effect on toe out on turns, probably more noticeable at low speeds on full lock.


Title: Re: What's the right length steering arms
Post by: fe350chev on June 07, 2013, 03:07:15 PM
Thanks Nes, and Velo you are right, but there are other little mods u need to make to get this setting  right.


Title: Re: What's the right length steering arms
Post by: FC427 on June 07, 2013, 05:41:42 PM
Anyone checking the toe out on turns? Using steering arms from models with a different wheel base may an effect on toe out on turns, probably more noticeable at low speeds on full lock.
Think you mean   Ackermann angle  will not be correct if tyre rod end is placed in the wrong location  by fitting the incorrect steering arm to the stub axle    .....FC427...... (http://www.urlaub-und-hobby.de/metallbaukasten/sonst/lenkung006.jpg)


Title: Re: What's the right length steering arms
Post by: fe350chev on June 07, 2013, 09:08:16 PM
Isnt that what shimming is for. Arent you both talking about the same thing in this case. In karting Ackerman gives you the "jacking" effect. No Ackerman and it feels like u are laden with bricks cos there is no differential to change rear end wheel speeds, so makes drag on engine because the back wheel wont lift off ground. If the steering geometry is not standard (from factory) and the correlational relationships of the geometry are changed like with using the hq arms (as with karting when you increase castor it makes the steering heavy on turns and increases the Ackerman effect causing the back wheel to come off the ground more like a diff effect), then the toe out on turns (or lack thereof) increases loads through the steering hub and king pins and knuckle, tyres etc because the inner tyre closest to the inside radius of the corner is having to travel more distance (or similar)  in relation to the right wheel, when in fact you want the opposite.

The picture of my sons racing kart might help u understand the tie rods on your rack better. See how it has adjustable points (3) along the steering arm (i think effectively like aftermarket holden spindles) with funny notches in the top 2 rack mounting points (call it a rack for this) of differing shapes. Most guys want standard ackerman so just use the standard holes at the back cos ackerman is built into the arm at the factory the same as say hr/hg curved steering arms that they are built with. HQ short steering arms are not the go in my opinion, even though I havent tried it, but I am researching for myself. They are too straight so no curve built in, which affects the relationship btw the ball joint to the steering axle turn point and subsequent tyre angles on full lock. When we kart race with lots of hard turns a certain way, say lots of turn hard left corners that are slow sharp corners, u can change to the second slots on the steering arms on the kart, and using the multiple position loopy groove, actually "fine tunes" your left hand side (for example) to turn in more than the standard 3 degrees for "true ackerman" (quite a universal formula) to a front steering setup that bites hard and toes on turns more dramatically and at a quicker point, creating a very pointy front end steering setup for hard left cornering at the expense or right hand turns, so if u gain 2 tenths on 5 left corners and loose a tenth on 2 right hand corners, its worth it.

(http://i1182.photobucket.com/albums/x448/fewithrb40/IMAG0579.jpg) ($2)
(http://i1182.photobucket.com/albums/x448/fewithrb40/IMAG0580.jpg) ($2)

HG are shorter, creating the same effect as moving the pivot point on the kart of the tie rods further forward, (. but there is a variance that someone might be able to point out somewhere in those models). Although HQ creates desirable heavier steering like when u put the HQ power steer ones in, because your reducing mechanical advantage...of course ;) HOWEVER, steering arms look the way they do in different models for a reason. The steering rack mounting point comes into play and if this is not set at the right position (forward or rear) then the only way to rectify this is to change your rack position or shim the mounting points in the steering knuckle/spindle assembly. The closest correct one (I believe) is HK-HG steering arms, but as Ken rightly points out, you are better to stick with HR ones than using HQ. Torana wont work either i believe. So I hope I am fairly correct for the best possible setup for your application, which is the same application I am embarking on.

The easiest way to check it, which is a good backyard method, is to open your garage door, measure get a cheap straight laser from bunnings, drive the car straight up the drive facing the garage walls, but needs to be a flat surface leaving room at front, perhaps with wheels on concrete edge, mark the centre of tyre with chalk on both sides and measure them from centre to centre. set up the 2 lazer sticks for straight ahead and tape them into a position facing the wall until you get an even measurement straight ahead. Once same distance of beams and physical tyre width same, mark with a straight edge with chalk on the ground where the beam is. then turn wheels as far to the left as possible marking the beams on the ground. Then turn lights on and get a large set square and measure the difference between the right one and the left one, aim for greater than 3 deg difference but less than 5. Doing it at the centre means that other mods wont matter in the result. BUT Its much easier to get a wheel aligner to do it  :D but who wants to keep paying for that. It sounds harder than it is but you need to be accurate with your line drawing.