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PollyMobiles Rebuild

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pollyp

pollyp

Club Member
Ok my plan to corner balance tday in daylight is ruined cos I have to goto a family new years gather, so won't have any daylight footage of the balancing when I do it later tonight :/
 
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pollyp

pollyp

Club Member
Corner Balancing the BC V1 Coilovers 01/01/2014

It's now 4pm in the dark so don't have any video footage but this is how it went.

First with the car in the garage, I mark out where the tyres are with ducktape

DSC08917.JPG


placed the rotary laser in the middle, levelled the bubble, place the first digital scale at the highest end which is the rear left corner

DSC08918.JPG


I place a canister cap at the highest corner of the digital scale, mark where the laser level is.
now I adjust the digital scales screw-on feet till all 4 corners hit that mark on the cap meaning it's flat & level.

DSC08919.JPG
DSC08920.JPG


I adjust the other 4 scales till they're all flat and level to the laser line.

DSC08922.JPG


moved the scales out the way, drove the car in at the same spot, jacked it up and placed it on the scales.

DSC08923.JPG
DSC08924.JPG


Test 1
so the first test of the car in its initial state.

fuel half full
no driver/passenger ballast (wanna see if the car weight is near the scales limit, and will have a passenger on the track so the body weight on both sides prob evens out)
no dumbell ballast yet
unbalanced coilovers
uneven tyre pressures

(weight / ride height)
FR 283.5kg / 117mm
RR 182.9kg / 100mm
RL 165.5kg / 108mm
FL 271.9kg / 116mm

Screenshot_2014-01-01-23-15-52.png
Screenshot_2014-01-01-23-16-21.png


The crossweights ok, it's very RH heavy, front ride heights are 10mm too high and I forgot to pump up all the tyres to the same warm pressure of 3bars so this reading doesn't count.
What I wanted to find out is if the front end is within the scales max 300kg limit, it's quite close so definately won't be adding the 75kg driver/passenger sandbag weights

Test 2
all tyres pumped up to the same warm pressure of 3bars
front preload reduced by 10mm

(weight / ride height)
FR 287kg / 104mm
RR 173.3kg / 104mm
RL 168.9kg / 104mm
FL 266.6kg / 104mm

Screenshot_2014-01-01-23-17-01.png
Screenshot_2014-01-01-23-17-33.png


ride height from rim to arch of all 4 corners are equal
the FL/RR crossweight needs increasing and the red center of load dot tells me I need to apply ballast towards the FL corner whilst maintaining the same ride height.

Test 3
I added the old 4 x 7.5kg dumbell ballast block back into the passenger footwell



(weight / ride height)
FR 295.6kg / 101mm
RR 170.7kg / 104mm
RL 178kg / 103mm
FL 281kg / 101mm

Screenshot_2014-01-02-00-26-52.png
Screenshot_2014-01-02-00-26-58.png


the passenger ballast almost equalises the center of load, lowered the front height by 3mm but the FL/RR crossweight still and FL corner still needs more load

Test 4
I increase the FL preload by 1mm to push the wheel harder onto the scales and to increase the FL/RR crossweight

(weight / ride height)
FR 293.3kg / 100mm
RR 173.4kg / 101mm
RL 174.7kg / 105mm
FL 284.8kg / 105mm

Screenshot_2014-01-01-23-18-08.png
Screenshot_2014-01-01-23-18-21.png


cross weight is getting better but LH ride height needs reducing

Test 5
Let's fit the remaining 7.5kg ballast in the FL of the engine bay to further increase load at that corner and lower the LH ride height



(weight / ride height)
FR 296.2kg / 100mm
RR 171.7kg / 101mm
RL 175.3kg / 104mm
FL 290.3kg / 102mm

Screenshot_2014-01-01-23-19-01.png
Screenshot_2014-01-01-23-19-09.png


much better. I cannot add any more weight to FL cos the digital scales are near maxed out and all the ride heights except the RL are equal.
next move is to reduce the FR/RL crossweight by reducing the RL preload which would also lower that ride height.

Test 6
Reduced the RL preload

(weight / ride height)
FR 294.6kg / 100mm
RR 174.5kg / 103mm
RL 173.5kg / 103mm
FL 292kg / 100mm

front strut lower mounts are both 180mm (where the lock ring meets the lower mount) from the top of the damper body.
front preload (measured from the alloy spring seat to the top of the damper body) are 102/104mm (left/right).
rear preload (from very top of the alloy preload ring to the top of the screw base) are 36/35mm (left/right)

Screenshot_2014-01-01-23-20-44.png
Screenshot_2014-01-01-23-20-58.png


well that's bout as close as I'll get.

Next lets check the tyres sidewall height vs pressure vs scale load.
the tread depth are a big influence on the sidewall height so the depths are
FR 6.75 6.75 6.50mm
RR 5.25 5.00 5.25mm
RL 4.50 4.50 4.50mm
FL 6.25 6.50 6.00mm

Test 7
so with equal tyre pressures the readings are

(weight / tyre pressure / rim to floor)
FR 294.7kg / 3 bars / 71mm
RR 174.2kg / 3 bars / 71mm
RL 173.6kg / 3 bars / 69mm
FL 292kg / 3 bars / 68mm

Screenshot_2014-01-01-23-23-54.png
Screenshot_2014-01-01-23-24-08.png


the FR/RL crossweight needs reducing without altering the preload which'll alter the ride heights and can't exceed the tyres 3 bar max pressure so lets reduce the FR pressure to lower the FR/RL crossweight.

Test 8
reduced FR pressure.

(weight / tyre pressure / rim to floor)
FR 294.4kg / 2.9 bars / 72mm
RR 174.7kg / 3 bars / 70mm
RL 173.3kg / 3 bars / 69mm
FL 292.4kg / 3 bars / 68mm

Screenshot_2014-01-01-23-24-39.png
Screenshot_2014-01-01-23-24-53.png


its interesting to see how much effect a small change in tyre pressure has on the tyres load. just 0.1bars affected the load by 0.5kg

well there you have it, that's pretty much bang on 50/50 :cool: and I'm completely exhausted from this back breaking work

here's an interesting imprint of how much contact patch there is between the tyres n road

DSC08925.JPG


FL / FR

DSC08930.JPG
DSC08926.JPG


RL / RR

DSC08929.JPG
DSC08928.JPG


last step is to tighten up everything, refit the rear spring covers, laser align the wheels and it's ready
 
OP
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pollyp

pollyp

Club Member
drove down the road briefly to warm it up.
after refreshing the rear calipers the brake pedal has a lot of travel before biting, prob needs more bleeding.
laser level up the 4 ball bearing platforms on the garage.
parked car in n placed on the platform.

starting to rain hard and soak the garage :(
front static camber set to 2deg.
FR wheel straightened.
FL tie rod thread quite seized, really should've overhauled the threads before I began the alignment, it's close enough to straight so I'll leave it for now.
it's late, dark, cold and my clothes all drenched n miserable from laying on the wet pooling garage floor :(
late slower n bed

next is anchor the passenger ballast, fit the swaybars, bleed the brakes
 
OP
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pollyp

pollyp

Club Member
You have an interesting way of corner weighting a car but I'm glad you have had a go at it :)

Any further with the app?
thx, it's a constant learning r&d process. have an idea, research, prep, try it out, test, review and repeat.
we'll find how it handles in the next trackday.

the last screenshots posted was how the app looked and have added that front/rear left/right bias value you suggested and was useful.
I'll be refining the graphics next week at work before it's ready to be released on the app store :)
still lots to be refined n added but it's a start
 
thx, it's a constant learning r&d process. have an idea, research, prep, try it out, test, review and repeat.
we'll find how it handles in the next trackday.

the last screenshots posted was how the app looked and have added that front/rear left/right bias value you suggested and was useful.
I'll be refining the graphics next week at work before it's ready to be released on the app store :)
still lots to be refined n added but it's a start
Trial and error is the only way to get results :) Its good to see different approaches to the same task

I noticed you'd added it in. Helped me keep up with each of your tests :) you see axle bias as well as overall corner and cross weight percentages

Another little idea... would it be possible to add in a ballast on the app? For example driver weight? As you couldn't exceed the scales but it could help adjustments? Just a thought :)
 
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pollyp

pollyp

Club Member
Trial and error is the only way to get results :) Its good to see different approaches to the same task

I noticed you'd added it in. Helped me keep up with each of your tests :) you see axle bias as well as overall corner and cross weight percentages

Another little idea... would it be possible to add in a ballast on the app? For example driver weight? As you couldn't exceed the scales but it could help adjustments? Just a thought :)
indeed I can add the amount and bias of ballast to the load distribution.
in terms of accuracy, telling the app where u estimated that extra weight would be and how it actually affects the load readouts could be different but for estimation of where to place additional ballast on top of the drivers weight, it'll be handy.
 
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pollyp

pollyp

Club Member
tday bled the rear calipers and a tiny bit of air came out. test drove and yep it feels alot better now.

also time to overhaul the steering rod threads

DSC08931.JPG


loosened the locknut but the tierod end was totally seized onto the steering thread :/

had to clamp the rod tight and required alot of brute force to slowly unscrew the end

DSC08932.JPG


there's ur problem, the thread had dried n rusted seized

DSC08934.JPG


retapped

DSC08935.JPG


and regreased

DSC08936.JPG


such a crucial adjustable component but left exposed to all the elements and made to seize?
think it's a good idea to cover the threads like my coilover covers.

just the front swaybar to fit and realignment
 
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pollyp

pollyp

Club Member
so this morning all the cold tyres started out as 3bars,
the turbos cold start seems too rich 9afr and too low rpm, had to hold the throttle briefly till she clears the oil out of her cylinders.
once O2 was warm and we're cruising, afr is fine.


fuelled up and drove to the country to test the balance


driving back home from the country


so alignment wise, the car travels straight when the steering is straight but she drifts to the left on all sorts of roads.
all brakes feel the same temp so no extreme binding.
after the first initial driving, the warmed tyres were 3.10 3.10 3.10 3.20bar (fr, rr, rl, fl)
reduced their warm temps down to 3bars
tonight the cold tyres are now 2.85 2.95 2.95 2.85bar (fr, rr, rl, fl)
so the brakes, tyre pressure, tyre heights and alignment all seem equal n straight, need to investigate why it pulls.

suspension wise, I know I haven't driven her for awhile and it's only been on normal damp dirty cold public roads but the handling feels so much more stable, smoother and sticks like glue.
the rear end with the full damper travel no longer crashes over big bumps.

engine wise, after fitting the turbo, the piston tops have dried up back to slightly damp from the positive pressure and after tdays driving, the level has gone from full to 4/5th.
compression has gone from 12 to 11bars now prob due to the reduced oil pool in the cylinders.

once the slight pulling is sorted, she'll be spot on
 

Enuo

Glorified Electrician
You need to test on a perfectly flat road, road camber tends to pull you left. Some alignment places actually set the steering to pull the car slightly to the right to counter this.
 
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pollyp

pollyp

Club Member
looking at some readings I think one of the causes is tread depth.
even though the pressures, wheel alignment and corner balance may be equal, I noticed the RH tyres are 0.5 - 0.75mm thicker than the LH.

I'll swap the tyres left to right to check if thats true.
then I'll check the calipers for any uneven binding
 
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pollyp

pollyp

Club Member
Its because left/right balance is equal so it'll pull left whatever you do
yea the front wheels are dead straight with zero toe but 2deg camber both sides.
drive on the other side of a calm road to test if it's the road camber?
 
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pollyp

pollyp

Club Member
ah just realised from the corner balancing that most of the tyres were 3.0 bar while the FR tyre was 2.9bar (prob due to the thicker tread) but tday after the initial drive I forgot I matched all the tyres to 3bars (so the FR will be slightly higher) which may have contributed to the pull.

so in the morning I'll reduce the FR tyre by 0.1bar
 
To be perfectly honest I'd leave tyres on each axle the same. That's affecting contact patch and ideally needs to be the same across an axle
You'll find out what I mean on a hard corner on track :)
 
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pollyp

pollyp

Club Member
ideally if all the treads were the same depth yes, but here my right treads over 0.5mm thicker than the left (cos of the road camber and turning right on roundbouts more often than left) hence I had to deflate the FR tyre to balance the scale.

if only I could diagonally rotate the tyres or left to right but these are directional.
reading one website bout alignment, one remedy would be to reduce the FR negative camber to be more upright making it drift more to the right and counteracting the camber of the leftward sloping roads.
 
I've never worried about tread depth in relation to corner weighting to unless its of a great difference 8mm and 2mm for example. Getting the heights all the same is not the priority.
Having unequal tyre pressures has a larger effect on handling than spring preload. Hence keeping them the same over one axle.
Having a 50/50 balance but then uneven tyre pressure conteracts the weight balance you've set up

To my knowledge tyre pressures are always considered a separate entity to corner weighting
 
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pollyp

pollyp

Club Member
suppose I should've just reduced the FR preload rather than the pressure. we'll try once again soon.

this morning lowered the FR down to 2.9bars and still pulls so gonna swap wheels over in abit.

also been looking at trackdays and the cheapest & nearest one I've decided to goto is Elvington Airfield in Yorkshire Jan 19th Sunday £99 open-pit all day.
anyone wanna join?


holy moly just googled the track and it was where hammond had his massive crash :eek:
 
Its a bit soon for me or I'd go with you

As a basic rule of thumb, ballast and preload are static weight balance
Height is cross weight :)
 
suppose I should've just reduced the FR preload rather than the pressure. we'll try once again soon.

this morning lowered the FR down to 2.9bars and still pulls so gonna swap wheels over in abit.

also been looking at trackdays and the cheapest & nearest one I've decided to goto is Elvington Airfield in Yorkshire Jan 19th Sunday £99 open-pit all day.
anyone wanna join?


holy moly just googled the track and it was where hammond had his massive crash :eek:
Can I join ? Also can I bring any car up ?


Sent from my iPhone using Tapatalk
 
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pollyp

pollyp

Club Member
I believe any spectators can come along.
If organisers allow, I think extra passengers can register on the day at £5 plus £20 helmet
 
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pollyp

pollyp

Club Member
here's footage of what to expect on a driving experience day at that track.

edit: boy I'd luv to drive an mp4-12c or especially a P1, my dream car cos I've sketched such a car years ago and mclaren has made it real :p


I find they usually run driving experience sessions seperate to public enthiusiast trackdays, most likely for maintaining a safe controlled environment (supervised by trained experts) and insurance (less chance for some banger driven recklessly from smashing into a million £ supercar)

for the dedicated public trackdays like what I booked, here's another example footage

 
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pollyp

pollyp

Club Member
hmm I figure the track will wear these brakes in no time so better order summore.

getting harder to track down a pair of black diamond predator FT pads for a GTIR.
either £81 from motorspeed.com
http://www.motorspeed.com/Nissan-Su...nd-High-Perform/brand/18/product/680/veh/2507

or £47 from needforspeed.co.uk
http://www.needforspeed.co.uk/pages/sbv_pl.asp?Vehicle=NSSUN01&PartType=BRB03

or £34 from demontweeks on ebay, but dunno if they're just "fast road" or "fast track"
price seems to suggest they're just Fast Road, lower working temps.
http://www.ebay.co.uk/itm/Black-Dia...t-Pad-Set-Sunny-GTI-R-N14-92-93-/190859706690
 
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pollyp

pollyp

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driving back home she still pulls left, so initially thought bout swapping the current tyres left to right but then thought what about the spare set of rota's I have with t1r's?

measured them and they're both equally 6mm :) whereas currently the fronts are 0.5 - 0.75mm offset and rears 0.5mm offset.

DSC08938.JPG


pumped the spare set to 3bars, fitted onto the front and tested on the motorway and OH YEAH it now travels laser straight :cool:
so satisfying when it no longer pulls and don't have to correct the steering all the time.

so there you have it, twas the difference in tread depth which caused the steering to drift over like a cone cup
 
Motorways have less camber than single carriageways?
Still struggling to see how 0.5mm of tread depth can cause a car to pull :confused:

To add an explanation to my comment.
When you corner weighted the car it was a 50/50 l/r balance static with no driver.
Adding driver weight, will pull your balance over to the right, would suggest to me pulling to the right if anything? And assuming its a factor, cancel out out the tread depth difference?

Not me telling you you're wrong just seems inconsistent with your setup
 
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pollyp

pollyp

Club Member
You'll have to start rotating the tyres more frequently eh
can only safely rotate em back to front cos they're directional tyres.

actually my next debate is which set of tyres to run on the track soon?
I have:
1 x toyo @ 6.75mm
3 x toyo @ 6mm
1 x toyo @ 5mm
1 x toyo @ 4.5mm
1 x bridgestone @ 4mm
1 x avon @ 2.5mm

have 2 strategies:
1. run with the good set of equal treaded 6mm toyos to get the most out of the balanced setup on this track,
which'll ruin/shred the good toyo set and if they're totally worn, end up using the mixed uneven tyres for the road.

or 2. run on track initially with the worn avon/bridgest at the back, 6.75mm toyo at the loaded FL (FL wears the fastest) and 4.5mm toyo at the FR.

the balance definately won't be right initially cos of the mix match so will have to deal with it but will allow me to quickly wear through them (get rid of the bad batch quick) so that afterwards the worn set can be upgraded for some better 595RS-R for the next trackday.
now once the bad batch had worn out by the afternoon, I could then fit the good equal set of 6mm toyos to fully utilise the balanced suspension and then drive home on the good set of tyres.

I think on a dry track it'll have to be option 2 cos the main primary objective of this trackday is to find if the extreme heat of a trackday resolves the forged pistons oil issue and may as well make use of the bad set of tyres for that purpose, then once that engine diagnosis test is done and the bad tyres are finished, fit the good set and enjoy the ride:cool:

then for the next trackday it'll be running fresh set of 595's

but if it rains then it'll be option 1, running the thickest best tyres in the wet cos unequally worn mixmatched tyres in the rain doesn't sound safe.
 
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pollyp

pollyp

Club Member
Motorways have less camber than single carriageways?
Still struggling to see how 0.5mm of tread depth can cause a car to pull :confused:

To add an explanation to my comment.
When you corner weighted the car it was a 50/50 l/r balance static with no driver.
Adding driver weight, will pull your balance over to the right, would suggest to me pulling to the right if anything? And assuming its a factor, cancel out out the tread depth difference?

Not me telling you you're wrong just seems inconsistent with your setup
think its a dual carriageway.
yeah kinda puzzling, woulda thought too that the drivers weight alone would pull it right and if I had carried a passenger it would've pulled left even more.

both right treads were actually 0.5 - 0.75mm higher than the left (I had this sorta problem before and testing swapping left to right would pull the other way)
but the result of fitting an equal pair of tyres has fixed the pull

well after this tyre alteration, I'm gonna have to rebalance it all over again aren't I eh
 
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