givemethebighammer
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| posted on 23/6/06 at 11:35 AM |
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Wheel spacers and scrub radius
I have been looking at my tiger from suspension setup with a view to reducing the amount of understeer the car currently has. I have managed to get a
little more caster with some adjustments which should help. My next move will be to increase the scrub radius by fitting some wheel spacers. The
question is how wide to go ? I'll be buying hubcentric spacers so they'll be £40 plus so buying several sets to try is not really an
option. I fitted longer wheel studs when I built the car so a spacer up to 20mm will fit without problems. So how much difference does 5mm, 10mm 15mm
etc make ?
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britishtrident
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| posted on 23/6/06 at 03:34 PM |
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Increasing the scrub radius isn't a good idea, it won't bring impending doom but a large scrub radius is best avoided among other things
it causes excessive steering kick back which is best avoided especially if you intend to fit a quick rack or a small dia steering wheel.
Also how many times to I have to say it hub centric spacers just aren't required.
Generally if the car is understeering soften the front roll stiffness, although having look over a few Tiger front suspensions it might be an idea to
see what happens to the front toe angles when the steering is turned --- as toe-in on turns will cause poor turn in and understeer.
[Edited on 23/6/06 by britishtrident]
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givemethebighammer
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| posted on 23/6/06 at 03:55 PM |
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quote:
Originally posted by britishtrident
Increasing the scrub radius isn't a good idea, it won't bring impending doom but a large scrub radius is best avoided among other things
it causes excessive steering kick back which is best avoided especially if you intend to fit a quick rack or a small dia steering wheel.
[Edited on 23/6/06 by britishtrident]
I thought this however I think the understeer may be partly due to a wide (sierra width) rear track and a narrower front track. I want to avoid the
spacers and I am trying other things first. Reading around the subject it seems that increasing the caster and scrub radius help with understeer
issues. I'm going to set the camber to about 0.75 degrees and the toe to straight or 1mm toe in them measure the change in toe through the
movement of the steering. It may be that I have too much toe in at the moment and too little caster.
ps I have a quick rack and a 300mm steering wheel so maybe increasing the scrub radius is not such a good idea.
thanks
[Edited on 23/6/06 by givemethebighammer]
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leto
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| posted on 23/6/06 at 10:42 PM |
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On the other hand, a lot of people are driving around with cortina uprights on similar cars. So scrub radius of 70-100 mm are not in anyway uncommon.
Not that I would recommend it .
“I'm gonna ride around in style
I'm gonna drive everybody wild
'Cause I'll have the only one there is a round”. (J. Cash)
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TangoMan
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| posted on 24/6/06 at 10:54 AM |
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Stiffen up the rear
Another way to assist with understeer is to stiffen up the rear.
This will prompt oversteer and will help to get a better balance.
If you want to test the wider scrub radius, try to borrow some wheel with greater offset before spending money on spacers. If you are using Sierra
offset, try Peugeto/Citroen offset as this will give you around 12mm extra.
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