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Too much Caster on LX

Started by _hyjinx_ , Oct 16 2018 12:51 PM

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#1 _hyjinx_

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Posted 16 October 2018 - 12:51 PM

Hi all

I have had an LX SS hatch, since 1990 that has, what I think, is a UC front sub-frame with aluminium mount steering rack.

 

I have HZ brake stubs with WB discs and aluminium calipers.

 

My question is, I have about 2.5 degrees of I think negative Caster (the one that makes the steering heavier).

 

This was done years ago when I used to race the car and now I'm driving it on the street more often I wanted to reduce the caster back to RTS specs to make the steering 'lighter', for want of a better word.

 

The car also used to run -5 degrees camber, great for the track but wanted less for the street.

 

Prior to being adjusted for racing the wheel alignment was standard RTS with -1.5 degrees negative camber.

 

I had the car wheel aligned by a reputable place and we got -1 degree camber but couldn't get less that 2.5 degrees of caster.

 

The wheel alignment guy suggested I get 3mm ground off the mating surface of the upper pivot arm to allow for more adjustment.

 

I know the front sub-frame has most likely sagged but over 15 years the camber/caster measurement hasn't changed except for what's been done recently.

 

Surely there is a better way to lower the caster than grinding the upper pivot arms?

 

thanks in advance

Hans


#2 76lxhatch

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Posted 16 October 2018 - 01:37 PM

I don't think you'd get (or want) 2.5 degrees negative so you probably mean positive.

There is always a compromise between camber and caster on these front ends, but its normally the other way round - i.e. you can't get enough positive caster without too much negative camber. If you can't get less than 2.5 degrees I'd suggest that something has been modified to achieve this. Are there offset bushings in upper or lower arms? Have the mounting holes for the uppers been moved?

However, it shouldn't be heavy at your current settings either and it would be nicer to keep as is - I had up to 5 degrees with manual steering and 255 front tyres and it was fine (now +6.5 with power steer and a few tweaks). Check the steering column bearings and intermediate uni joints are in good nick, as well as the rack itself.

If you really must reduce the caster and can't find the issue, swapping the UC upper arms out for some LH/LX ones would do the trick.
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