in sorting out n/s camber by adjusting lower transverse arm (has an adjustable inboard rose joint) this has thrown the tracking out.
Two questions.
1. To adjust tracking toe in/out can the steering rack end be turned after loosening the lock nut on the track rod end, or should the track rod end be disconnected and turned in or out? Hawk Herald rack.
2. Adjust castor is the solely by adjusting the bottom leading link (adjustable rose jointed)??
Hi Tim, there should be an outer track rod with an adaptor between it and the steering arm with a locknut on it, slacken this off, vice grips on the steering arm and spanner on the adjuster and screw the steering arm in or out as necessary.
Castor is adjusted on the leading link by lengthening or shortening in. I wound as much on as I could get but you have to watch that this doesn't drag the wheel so far forward in the arch that it fouls on the bodywork. The only caveat really is the inner mount on the lower wishbone, if it's rubber it's going to be under a little more strain and won't last forever. If it's rose jointed then no issues!
Craig has mentioned tyre pressures, i run towards the lower end with 225*50*15 on the front, back end has no camber with 345*35*15s.
Guy
So a bit of an update.
Using the parallel tub and straight edge of the rear wheel and some school boy trig I found OSR had 1 deg toe in and the NSR (in the photo!!) had zero!
So a bit of a fiddle on the nice adjustable trailing arms I got c0.4 degree toe in one both rear wheels.
Set the tyre pressure to 18 front 22 rear ground clearance front of tub (which is essentially a flat plate) 160mm, rear of tub 169mm so not pointing up!
Went for my 20 mile check run and the rear felt really planted, but am still not getting a stable front end at speed in a straight line. Steering and cornering so far feel fine but not exploring that. It needs constant input on the steering at ehem speeds in a straight line (like it is tram-lining all the time), not as bad as previously, so more toe in or less, and more caster (I am near the limit of the geometry already at around 5 degrees). I did not notice any bump steer problems.
Any chassis experts out there??
If I read your post correctly then 0.4 degrees per side is too much toe in IMHO, as stated in an earlier post rear toe wants to be in the region of 20 minutes total (10 minutes-1/6th of a degree per side)
The front of the chassis I would suggest to be 20 to 25mm lower than the rear of the chassis, normally measured at the front of the floorpan to the rearmost cross member.
I think you will always get some tramlining as the rear track of a GP4 is wider than the front track so the rear wheels will always follow a different section of the road. the wider the rear tyre the more I think it will show itself, I see you have the 295 TB15's though which shouldn't be too bad.
Constant movement of the steering wheel can be either bump steer or rear end tramlining, if you are happy that you have no bump steer then I would think that you are correct in the assumption that the rear is causing the issue.
Where are you with negative camber now?
Last edited by Strat Fan; 17-12-2015 at 18:33.
"You can lead a horse to water, but a pencil must be lead"
Stan Laurel
do you have any play in your front suspension ball joints and track rod ends?
Absolutely none. They are less than 5k miles old and were jiggled comprehensively by my MOT guy last week. Apart from the bottom suspension joint and track rod ends it is mostly rose jointed and quite quiet....But that would be a good place to look if the car had miles on it. There is no play in the steering either.Originally Posted by strat24v
Rear camber on group 4 tyres i run 0 deg due to width of tyre, one thing to check on the front end does the steering rack have any tight spots when jacked up with the weight of the wheels. On my Hawk the steering rack platforms had distorted due to welding and was putting a bow effect on the rack body when the clamps were tightend, I over came this by maching the inside of the clamps to a width of 3mm
Regards Ken
Update and back to chassis tweaking. Just went out again for another bit of excitement. Car is rock steady at speed but very sensitive to steering input with minimal self centering. I tried going up to 20 psi on the fronts which gave a v small improvement in self centering but not much off line. Under dynamic steering it feels great / just fine etc etc.
I have not stiction in the the steering and no wear. I also have upgraded rose jointed 131 uprights so dont think that geometery is at fault. I am coming round to the fact I am running Michelin race tyres TB15 215's on the front that have a very flat and sticky profile so will follow were they are point more than an ordinary tyre.
131? They should be 132 items.
What's your bump steer like?
Do you have a split alloy column bearing fitted?
Last edited by strat24v; 20-12-2015 at 15:39.
Typo yes 132! Bump steer how does one check this on the road? I hit a few bumps both cornering and straight at c70mph and the car was quite well behaved.
re column bearing are you referring to the top of the steering column?
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