geometry and spring setup

R

R called Jay

Member
Just wondering how you are adjusting toe on the rear?

Is there a mod you can buy or do i need to diy something?

With regards to tyre pressures, i use a temp gun and use that as how to adjust pressures once hot. Most manufacturers state recommended tyre temps.

But that does mean that I start with the fronts pressures lower than the rears as they create more heat than the rears.

Not saying its the right way to go about it as i've not found a setup i'm completely happy with yet.
 
stumo

stumo

Active Member
rear toe is adjustable on the car.,...you don't need to buy anything. look at the inner rear bottom pivot bolt......it's on an eccentric...
 
R

R called Jay

Member
Well thats something that I've not noticed during owning a pulsar for 9 years!

Cheers, was only setting things up last night and had 1deg toe in at the rear that i wanted to remove.
 
gtirx2

gtirx2

Active Member
What are your guys front negative camber settings like on the front?
Are they adjusted evenly,as in pushed back the same distance each side with the coarse camber mod.
Or is there always one side that you have to adjust more to achive the same camber each side?
Mine seems to have a lot more neg camber on the passenger side even before the coarse camber mod,around -0.8 to -1degrees more?
I have measured the chassis about a millon times know and changed every part and i still cant seem to fined the problem yet.
Also what makes me wonder if they are a bit different side to side is on the standard spare shocks i put on i also noticed that someone had done the coarse camber mod just on the passenger shock and not on the drivers shock.Just like i have to do to get the correct camber side to side?
Also how much would you guys expect the camber to change just from lowering the car to around 325mm at the front?
Mine on the passenger side is around -1.6degree and -0.7 on the drivers?
Maybe i am looking at the wrong side?
 
Trip

Trip

New Member
Took the car for wheel alignment and we did not manage to dial in more negative camber.

The rear camber is done via camber bolts and the front have adjustable top mounts with castor mod.


FRONT Left , Right
Castor: +3.36 , +1.91
Camber: -0.71, -1.51
Toe: +0.1, +0.08

REAR Left, Right
Camber: -0.72, -0.63
Toe: 0.016, 0.016


My worry is that the front are not equal to each other(left and right) even though the top mounts are set the same.

What options do i have to get equal on both sides and put in more negative camber ?
 
gtirx2

gtirx2

Active Member
Trip said:
Took the car for wheel alignment and we did not manage to dial in more negative camber.

The rear camber is done via camber bolts and the front have adjustable top mounts with castor mod.


FRONT Left , Right
Castor: +3.36 , +1.91
Camber: -0.71, -1.51
Toe: +0.1, +0.08

REAR Left, Right
Camber: -0.72, -0.63
Toe: 0.016, 0.016


My worry is that the front are not equal to each other(left and right) even though the top mounts are set the same.

What options do i have to get equal on both sides and put in more negative camber ?
Click to expand...
My camber is basicly the same as yours but the other way around,but without the castor mod.
I have still not found what is causing mine yet, but looking at your results i would guess that the uneven castor is the cause of the different camber results.
Also on mine when the wheels are in the air the left side is around 0 camber and 1.6 neg on the ground where as my right side is 2 pos in the air and 0.7 on the ground,so one side has almost 1 degree more of a camber change though out the full travel of the suspension?
I am pretty sure its got to be different caster angles causing it?
I will be checking my back wishbone bush for play and see if i can solve it but so far i have had no luck and i have measured everything.
Also with the varying cambers i think it puts the measurement between the front and back wheels out when you set the front toe,so one side will measure longer front to back than the other side?
 
Trip

Trip

New Member
update:

I followed Jim's advise and went for the camber mod. :) Managed to put -2.5 Deg of camber. I widened the extra hole on the turret a little as per Bobby's advise and i managed to get castor equal on both sides +2.3. Castor is probably still on the low side but it will do for now.

I had a problem with the spherical bearing thread part, on increasing the camber i had to toe out the wheel too but the threaded part of the bearing was hitting the tie rod. I had to saw off part of the thread piece to make it shorter to get 0.5 total toe.



I have raised the car from the back to get the difference 20mm front/back, i have adjusted the rear damping to hardest (16clicks) and front to 6 clicks.



On the whole the car improved a lot. But on WOT on 2nd gear, I have still a slight understeer with 0 oversteer. What i noticed is even though i have 2.5deg camber, i am still getting more rubbing on the outer part of the tyre, much more then the inner side.

 
T

Tim

New Member
What pressure are you running in the tyres, could they be rolling as you change direction?

Are you u sing an R Rated tyre or Slick?
 
Trip

Trip

New Member
Tim said:
What pressure are you running in the tyres, could they be rolling as you change direction?

Are you u sing an R Rated tyre or Slick?
Click to expand...
Tyre pressure was OK. I was running 225/45R16 Toyo R888 GG, Front 28psi and rear 26psi cold
 
campbellju

campbellju

Moderators
Staff member
Trip said:
to make it shorter to get 0.5 total toe.
Click to expand...
What are these units and is it in or out? 0.5degs its too much. If its toe out then that explains why your outside of the tyre is wearing so fast.

Your damper settings may be causing you problems as you have a lot of rear bias.

How setting is your Rear ARB? Going to the stiffest setting might help but you will need to reduce your rear damping.

There is a limit to what you can do with a 4/3 spring setup. If you are only getting understeer under WOT its not bad given the tyres are the same, the power is split 50/50 and the mass is at the front there is only so much you can do.
 
Trip

Trip

New Member
campbellju said:
What are these units and is it in or out? 0.5degs its too much. If its toe out then that explains why your outside of the tyre is wearing so fast.

Your damper settings may be causing you problems as you have a lot of rear bias.

How setting is your Rear ARB? Going to the stiffest setting might help but you will need to reduce your rear damping.

There is a limit to what you can do with a 4/3 spring setup. If you are only getting understeer under WOT its not bad given the tyres are the same, the power is split 50/50 and the mass is at the front there is only so much you can do.
Click to expand...
Hmm my mistake (typo),

Toe is -0deg 05min each side with total toe of -0deg 10min

Camber is -02deg29min = (-2.5deg) each side

I have set the rears to full hard (last click clockwise) and -10 clicks from hard on the front. So there is a difference of 10clicks between front and rear. The fronts springs are 8kg and rears are 7kg, although they seem too hard for the weight of the car, i didn't feel the car rigid.

The ARB is full hard too meaning the link is connected to the inside hole.



Car in action




As you are said Jim, these cars are front biased and there isn't much one can do. For the next race i have a tight slow U turn (round a small roundabout) i need to tackle and a little oversteer on exit would really help turn in faster (as long as i find power to exit it). If you wanna see it, here it is http://www.youtube.com/watch?v=VKO42SODQ3M


Much appreciated Thank you
 
campbellju

campbellju

Moderators
Staff member
The 8/7 springs I think Fubar uses on track and he seems to do alright. I run 5/4 which is less front biased than yours so I'd leave the springs where they are. I commute in my car so its at the limit of what's practical for rubbish UK B-roads.

From a setup perspective, a trick I did recently was switch my poly bushes on the Front ARB mounts to OEM bushes. It sounds counter intuitive but it really helps to get the car to bite in on corner entry and has made my car feel "fun" again. I've not tested it on a racetrack yet but on the road I prefer the feel. It may not work for you but the Nissan bushes are cheap and they take no time to change.

Aside from that its down to dampers with more front rebound compared to the back, start with less at the rear. Tyre pressures as has been said in the past and how you drive the car and set it up into a corner. There are better drivers than me out there so I won't embarrass myself on the last point.
 
campbellju

campbellju

Moderators
Staff member
P.S. count your clicks from the soft end not the hard end. Past a point the dampers are just hard and extra clicks won't have a significant effect. You might also find the dampers don't have identical number of clicks but the biggest effect is in the first 10 clicks.
 
campbellju

campbellju

Moderators
Staff member
Trip, I was thinking on my drive to work this morning a little bit of toe out at the rear might help to get your car to rotate. Try 5 mins total toe out as a starter if you've not already done it.
 
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