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Adding some caster
ArAKern - 4/6/18 at 11:10 AM

Well just had a great day on Friday with Matt at Procomp setting up the suspension on my phoenix it was an uphill battle mainly due to some less than stella chassis design decisions. But Matt's skill prevailed and when the new front dampers arrive should be all set.

One thing that could not be sorted was the zero caster built into the design of the front upper rockers arms (sierra uprights)
one option discussed (and seen mentioned on here before) is to shorten the pivot tube and add a spacer to move it backwards but this would gain very little caster.
others would be move the mounting points or have new rockers arms made with some caster built in.

Has anyone else tried to add some caster and what was the solution?

Many thanks for you thoughts ideas

[Edited on 4/6/18 by ArAKern]


pekwah1 - 4/6/18 at 11:24 AM

Hi,

I have inbound suspension on my striker and had to do exactly this for IVA and "self-centring steering"

I moved my arms back approximately 1-2" which has made a fair difference and certainly worked for IVA.

How much do you think you would be able to move your arms? The alternatively i guess is moving the lower point forwards as well / instead.

Andy


ArAKern - 4/6/18 at 11:58 AM

Andy sorry to question did you mean 1/2" ie 0.5" or were you able to move it back 1 to 2"?
If I am lucky and grind a little weld I might be able to move it back by 11-12mm at most.
This might give me ~3.7deg of caster if my trig is correct.

Moving the lower points is not possible without additional chassis modification feel it would be easier to move the upper points.

luckily I had no self-centring issues on my IVA.

Giles


pekwah1 - 4/6/18 at 12:08 PM

Hi,

I meant either 1 or 2 inches.
It might even have been a bit more but can’t remember.

I’m not exactly and engineer or anything and have no idea how many degrees I now have, but made a difference.

I’m assuming your driver for wanting some caster is just a stability thing? Do you have problems at the moment with stability or handling?


flanders - 4/6/18 at 12:11 PM

Could you fit Rose joined wishbones?


ArAKern - 4/6/18 at 12:20 PM

Flanders I am open to any ideas
but not seen any wishbones that have caster adjustment that would fit a phoenix with in-board suspension.

obviously I could have custom items fabricated with a fixed amount of caster and I am sure you could fab up some trick suspension pick up points to add in adjustment.

Having not seen the later striker and raw phoenix cars I am not sure how they are achieving caster adjustment.
(I assume it is fixed)


ArAKern - 4/6/18 at 12:44 PM

This is what I have currently

inboard rocker arm
inboard rocker arm



This is one method of adding caster by cutting down the pivot tube allowing the top rocker arm to move it backwards
(caster is limited by the amount of tube you can remove in my case about 12mm)
also moving the suspension pick up points would also work may allow for more adjustment

rocker arm edit
rocker arm edit



I do not have skills to design and fabricate a fully adjustable top rocker arm


pekwah1 - 4/6/18 at 02:54 PM

I have the same rocker arms on the striker, I simply took a hacksaw to the rear sides of the arm and then packed out with washers either side, in fact I’ve done this on the two strikers I’ve owned, it’s worked a treat!

I’ll take a photo if you want


ArAKern - 4/6/18 at 03:07 PM

Andy, A Photo would be great
Do the strikers arms have more available pivot tube length to cut that the 12mm I have on mine?

If could get 1 - 2" like you did that would give me all the caster I would ever need may be worth trying to source some striker arms if they are different.


pekwah1 - 4/6/18 at 03:20 PM

They use the same ones, but there’s a few different designs depending on what age. You can buy brand new ones from raw which are built with adjustment (they’re narrower and just pack out with washers).

I think I had that design on my first striker and just cut through a small amount of the larger part as well to give me slightly more if that makes sense