Lightweight Steering Rack Support

[Guest salty_monk]

2.8 is about right as you say..... A fiesta looks like

 

 

That!! (That's the go faster model that myself & Drew thrashed round the track on a club day....) Your rack is off a slightly older one though... that's a 92.

 

They are basically small engined shopping trolley's so I would think that they probably have closer to 4 turns lock to lock.....

 

Dan

[Guest zoomzoom]

Hi Scotmac

I think you might have to add some sort of support to the rack mounting. My kit came without the supports and I fitted the rack without them and the mounting plate moves and twists when the rack is turned, so i ended making up a set and fitting them, much better now.

Any chance of some pictures of the extra work you did to the chassis as they would be of great help to us.

We are having a meeting of minds here soon about getting our cars through sva and I am very interested to see the work you have done

 

Marcus

[Guest ScotMac]

Hi Scotmac

I think you might have to add some sort of support to the rack mounting. My kit came without the supports and I fitted the rack without them and the mounting plate moves and twists when the rack is turned, so i ended making up a set and fitting them, much better now.

Any chance of some pictures of the extra work you did to the chassis as they would be of great help to us.

We are having a meeting of minds here soon about getting our cars through sva and I am very interested to see the work you have done

 

Marcus

 

Thanks Marcus.

 

Guess i'll be doing some measuring and heading out to aluminum supplier then!! And i was hoping i was done w/ the custom work (is that ever the case for a hood???? )

 

I actually have a quite a few photos of what i have done to the l/w. I will try to get them together and post it in a somewhat coherent manner. Since it slightly off topic, i'll look back to one of numerous l/w strengthening threads and post there what i have done to date.

[E.Hunt]

Hi Scotmac

I think you might have to add some sort of support to the rack mounting. My kit came without the supports and I fitted the rack without them and the mounting plate moves and twists when the rack is turned, so i ended making up a set and fitting them, much better now.

 

Marcus

 

Hi marcus

 

I also wrapped the rack with rubber under the U bolts as most tin tops have some sort of bushing used .

[Guest ScotMac]

BTW, this brings up another question. The obvious way to dial out bump steer is to move the rack up and down until it cleaned up, for the amount of suspension travel desired. For the LightWeighter's, how much bump steer do you see on the l/w? ie, is the RH positioning of the rack in a good spot to get rid of the bump steer? (i am assuming that the LHD and RHD will actually end up positioning it in about the same spot, due to the exercise i just went thru above).

 

Cheers, -sm

 

I have figured out the answer to the bump steer question. It appears that RH has done a pretty good job w/ the L/W steering geometry, at least for the LHD version in conjunction w/ my Raceleda uprights.

 

Two main things are important, in terms of the steering rack and suspension (sorry for the background...if you are well aware this, or think i am BS, ignore it!!!! ):

 

1. The rack tie rods inner pivot point must be on the line between the w-bone inner pivot points. ie, if you create a plane by utilizing the 4 inner wishbone pivot points, the plane must bisect the rack tie rods right at the tie rod inner pivot point.

 

2. In order to ensure no bump steer, two ratios must be made equal. Ratio #1 is the distance between lower balljoint pivot point and the steering arm vs. the distance between the upper balljoint pivot point and the steering arm. ie, the distances on the upright between the lower suspension pivot point and the steering arm and upper suspension pivot point and the steering arm. Ratio #2 is the analogous distances on the inner/chassis side of the front suspension. ie, the distance between the lower suspension inner pivot point and the steering tie rod vs. the distance between upper suspension inner pivot point and the steering tie rod. Sorry if that isn't clear (Nigel, can you help me out w/ one of your famous diagrams? ).

 

Well, the fiesta rack i have been talking about appears to meet point "1" above fairly well (lines up w/ the chassis side suspension line).

 

In terms of point "2" (the bump steer ratios), my upright side ratio appears to be about 1 3/4" to 7 1/4". ie, the steering arm is about 1 3/4" from the bottom pivot point and the distance between the ball joints is about 9" (9" - 1 3/4" = 7 1/4"). So, the steering arm is about 20% "up" from the bottom pivot point. The distance between the w-bone pivot points on the chassis side is about 8 1/4". So, that means that the rack tie rod needs to be about 1.6" (20% of 8 1/4") up from the bottom inner suspension pivot points. Again, RH did pretty well. It'll need a bit of tweaking, but RH is close enough that tweaking shouldn't be too hard. In fact, if you look at the big hole that RH cut in the side of the l/w chassis for passing the tie rods through, the center of it is about 2" up from the inner lower suspension pivots points....close to my 1.6".

 

What about the RHD L/Wers (ie, *everyone* else!!! )? How well does yours line up?

 

Cheers, -sm

[Guest zoomzoom]

Ok I'm up to my furry arms in alloy box section,5mm plate and enough bonding agent to glue wembley stadium together and you want me to start measuring distances?????????? (and in imperial)

 

 

Ok I'm off tomorrow and will do and let you know (I'm using the standard sierra uprights)

Guess you want it done at ride height and at about 1 degree camber? castor is at max allowed with the mushroom inserts.

 

regards Marcus

[Guest gdc]

marcus

 

let the bear do it and go to work

 

regards graham

 

ps you got box alloy ?

[Guest ScotMac]

Ok I'm up to my furry arms in alloy box section,5mm plate and enough bonding agent to glue wembley stadium together and you want me to start measuring distances?????????? (and in imperial)

 

 

Ok I'm off tomorrow and will do and let you know (I'm using the standard sierra uprights)

Guess you want it done at ride height and at about 1 degree camber? castor is at max allowed with the mushroom inserts.

 

regards Marcus

 

Hey Marcus, yes, every piece of my wardrobe (if you can call it that!) has atleast one spot of glue on it!!

 

Note, if point "1" is met, the ride height shouldn't matter. ie, since the tie rod pivot point is on the plane w/ the inner suspension pivot points, movement of the suspension up and down shouldn't matter. If point "1" is not met, then yes, all bets are off!!!

 

However, the mushroom insert *definitely* does matter! ie, the height of it will definitely impact the upright side of ratios for point "2". So, just do your measurements w/ it positioned where ever it will be finally positioned when the car is done. In fact, from the 2b guys, i believe it is supposed to be positioned as far outboard as possible. ie, straight out, instead of back to maximize the caster.

 

Cheers, -sm

[Guest gdc]

scott mac

god you can type fast

[Guest ScotMac]

scott mac

god you can type fast

 

By product of my job....when i am not working on the car!

 

BTW, what is w/ the huge ebay clearinghouse sale???

 

BTW2, in all those huge amount of sierra parts, do you have a steering collumn?

[Guest zoomzoom]

Ok will do,

Inserts will be all the way down in the uprights and set to produce max castor (I heard that there can be problems in self centering), but my first thought on the steering geo was that it look about right

 

Ok will do,

Inserts will be all the way down in the uprights and set to produce max castor (I heard that there can be problems in self centering), but my first thought on the steering geo was that it look about right

 

Ok will do,

Inserts will be all the way down in the uprights and set to produce max castor (I heard that there can be problems in self centering), but my first thought on the steering geo was that it look about right

[Guest gdc]

marcus

your rambling

 

a product of building a lightweight

 

regards graham

[Guest ScotMac]

Ok will do,

Inserts will be all the way down in the uprights and set to produce max castor (I heard that there can be problems in self centering), but my first thought on the steering geo was that it look about right

 

Ok will do,

Inserts will be all the way down in the uprights and set to produce max castor (I heard that there can be problems in self centering), but my first thought on the steering geo was that it look about right

 

Ok will do,

Inserts will be all the way down in the uprights and set to produce max castor (I heard that there can be problems in self centering), but my first thought on the steering geo was that it look about right

 

Sounds good marcus....and you also type very fast, though a bit repetitively!!!

 

[Guest zoomzoom]

Sorry breathed in too much glue

 

Want to add a pic but it wont let me

 

 

 

Oh now it has

[Guest ScotMac]

Sorry breathed in too much glue

 

Want to add a pic but it wont let me

Oh now it has

 

Hey Marcus, nice picture, including the bears!

 

You suspension looks good. However, your top w-bone upright side pivot point looks bit higher than mine, and your rack tie rod looks fairly high in the cutout hole...somehwere around the middle (2")....and your steering arm mount looks pretty low (like my raceleda one). The higher top bone will increase the ratio on the upright side (increases the distance above the steering arm), whereas the higher rack tie-rod will decrease the ratio on the chassis side (decrease the distance above the tie-rod). This will work against each other to create more bump steer.

 

You should verify what i am seeing w/ exact measements (could be my eyes or an optical illusion!!). If it is true, then you might want to think about dropping your rack mounting point a bit down, or lowering the mushroom/top balljoint mounting on the upright (probably not possible).

 

-Scot