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PollyMobiles Rebuild

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pollyp

pollyp

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just went for a drive and the steering shake is kinda still there :(

with warm engine, retested compression with new gauge and its reading 10.4 10.4 10.6 10.6 bar
pistons still kinda looking damp but think all the signs are improving?

ok so with a 8:1 ratio that's 84% of the stock 9.5:1
the stock compression should be 11-14bar while the forged pistons should be bout 9.3 - 11.79 bar

so seems the pressures are on bar ( no pun :p )
 

r-reg-sr

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these track rod ends ware out quick ? maybe just enough for wobble? always ready to fling idea's at you :)
 
You can probably work it out easily Paul but I've a compression comp calculator I can email you bud. It's interesting to have a play around with :)
 
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pollyp

pollyp

Club Member
went to national tyres to balance all 4 wheels for £26 and the 70mph vibrations now fixed :D guy said they were all slightly off balance.
 
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pollyp

pollyp

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least there's no more shaking.
that initial £10 front wheel balance from last month was a waste.
always makes me nervous when some else works on my car.
can hear em scrape the wheel centre hole along the balance machines threaded shaft :/ or jacking from the rear sill, which tends to annoyingly bend the sill lip abit, or tighten the nuts beyond 108Nm.
 
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pollyp

pollyp

Club Member
Corner Balance & Align Wheels

Now that the good set of wheels are balanced & no longer shake, I noticed that the steering has been off-centre and the inner front tread has been wearing rapidly recently, thought it was from the 2deg camber and unbalanced coilover? (cos this suspension was last balanced in Jan with the uneven bad set of tyres)

So now is a good time to balance the suspension for these tyres and realign the steering.

first set all tyres to 3bars and checked tread depths are:
FR 4.75 5.50 5.25
RR 5.00 5.00 5.00
RL 4.25 4.00 4.25
FL 4.75 5.25 5.25
pretty much equal left/right but scrubbed inside tread.

painted 4 spots on the garage where each pad will be placed

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laser levelled the platform scales

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POV of balancing the coilovers


Beforehand the scales read

1.jpg


I increased the FL preload to raise the height & shift crossweight over to the FL/RR and result in this

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Add drivers weight to the RH and it'll be as close as it'll do.
Next I swap the front scales with my ball bearing pads to laser align the wheels


Initially the front wheels had massive amount of toe-out (haven't touched the alignment since Jan), no wonder it was wrecking the front inner shoulder.
Realigned it and now it tracks down the motorway dead straight :cool: hopefully stop it from shredding fast.
 
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pollyp

pollyp

Club Member
I thought bc coilovers had separate height and preload adjustment on the front?
It wasthe increased preload to increase height that confused me..

imo kind of (assuming during static height that the springs still compress and the dampers are sitting within their working travel and not topped out or droop limited).
the upper ring affects where the spring sits relative to the (shock body/bumpstop/hub)
while the lower ring affects where the (spring/shock body/bumpstop) sits relative to the hub.

raising just the upper ring or raising the (upper ring/shock/bumpstop) assembly up from the lower hub will both end up pushing & compressing that spring up harder against the chassis to raise that diagonal cross weight = increased corner load & corner ride height.

difference between adjusting via the upper or lower ring is how much bump travel is available plus how far away from the arch the tyre would be when the shock body hits the bumpstop, prob explained bout this in my first corner balance post.

the lower ring has been adjusted so that when I hit bumpstop, the hub just about prevents the tyre from striking the arch. this gives me maximum working bump travel between the static ride height & bottom out.
if I raise the lower ring to lower ride height/reduce crossweight, the wheel will strike the arch before bumpstop.
if I drop the lower ring to raise that ride height/crossweight, I'd be sacrificing precious bump travel, comfort and traction in order to prevent the wheels striking the arch.

I adjust via the upper ring to affect only the corner load & ride height without the drawbacks above.
 
The upper rings are for preload only... They are to compress or captivate the springs whilst the car is at full droop. The weight of the car will settle the shock in the optimum position.. this is where and how spring rate and/or length is chosen.. but springs should always be captive assuming you will reach full droop. In cases of much stronger springs where they may not compress to the correct height.. that's where the helpers come in and compress sufficiently to put the spring in the correct position. But are there to retain captive springs at full droop

The lower rings are for height only.. As the springs are captive and shocks in optimum travel position due to rate, you can adjust height seprately from preload. So that you dont overly add preload to a single spring adjusting crossweights. The idea being to get preload to 0 to get full use of the spring and are measured from the thread on the coilover not the arch to wheel as no car is considered "dead square"

In corner weighting you never adjust 1 corner you always adjust all 4 in smaller measurements.. Example being your need to crossweight shift from FL to RR... If the adjustment was 10mm
You'd lower FR and RL 2.5mm each. This lowers your crossweight "pivot point" so your subsequent adjustment has greater effect.. meaning less adjustment is necessary now 2.5mm instead of 10mm. Adjusting preload 10mm on 1 corner now gives that one corner 10mm more bump travel in your case than the other 3 corners. Meaning your cornering characteristics will change dramtically. For example, you'll now have to push harder in right turns that left because you'll need more weight transfer to compress the pre-loaded spring

To try and have a car perfectly even in height is scandalous is nye on impossible and deviates from the objective of 50:50 balance and in optimum travel location, otherwise you just wind them up to the same point on each side. This is why there are so many springs rates and sizes available and so much adjustability within a coilover unit :) to even out the small gaps in travel you use adjustable anti roll bar links to pull harder one side or release tension from another side to control travel

It gets even more complicated than that in reality. As you start to add more complexity to the setup, anti-roll bars, knife length, castor angle, SAI, Camber and Toe will all contribute to handling and refining it... but never contribute other than component mass to cornerweighting. I never did finish my corner weighting guide. Only the process to corner weight the car for less than £10 although I did add some details to it. I'll do a full adjustment guide when I get the opportunity :)
 
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pollyp

pollyp

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hiya haven't posted cos been too busy n tired with work.

indeed trying to explain suspension stuff is complicated, think I need to model my chassis & suspension in 3D one day to help visualise the geometry involved.
hmm just realised that I forgot to unhook the swaybar during balancing but meh, its only being used on road for the moment so tis a minor thing.

the wheels bump travel, from the target static ride height you chose to just before the tyre hits the arch, is a fixed distance.
imo the purpose of the lower ring is to adjust the available "bump travel" at static ride height so that when the damper hits the bumpstop, it "stops" the wheel from hitting the arch.
once the lower ring is set, imo you leave it alone.
you don't use the lower ring for height adjustment cos as explained before, it will alter where the wheel is when you hit bumpstop.
raising the lower ring too high and it'll rub the arch. too low and you lose bump travel so the damper keeps hitting the bumpstop.

the upper ring is where I believe you set the preload against the chassis weight & ballast, which then affects corner ride height & corner load.
starting with a spring set at zero preload @ full droop:
if the height was slightly too low, we can just raise the upper ring afew turns to increase preload & ride height abit.
if it was wayy too low and can't apply anymore preload by hand, we can fit a harder spring.
if its too high at zero preload, we can either fit a softer spring or increase the corner ballast or drop the upper ring below zero droop (so the chassis & spring sits lower) and fit a short low-springrate helper/assister spring to take up the slack during full droop.

I usually finetune the preload via the front struts only cos the rear springs are an absolute PITA to access and cba :p

tis true that the tops of the wheel arches are not perfectly level to each other. measuring between the upper/lower spring perch and getting the left/right distances equal while also achieving 50/50 scale crossweight is prob a better way than via wheel arch but abit more difficult.

I just need it to be near enough and not after perfection cos tbh I don't think I can tell the tiny difference amongst the other issues such as binding swaybars, damper seal friction, +/- 1kg digital scale inaccuracy, slightly uneven chassis cos of that hidden botched front end, chassis flex, uneven tread wear, varying passenger weight, uneven fuel tank weight distribution cos of fuel sloshing to one side during cornering, etc.

with so many variables imaginable, I just get it 95% near as I can and just drive it for fun and not 10th/sec racing. I don't have the patience or resources to be "that" detailed for the last 5% if it makes any difference tbh.
 
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pollyp

pollyp

Club Member
took afew more compression readings with the gauges new valve and it's now giving a stable reading of 10.5 10.5 10.5 10.6bar

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also logging more dipstick readings and notice how consistantly steep the level drops every time I refill it. so seems it still burns oil at the same astraunomical rate :/

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I removed the "100% full" readings from this graph since I could've over filled it slightly. but looking at the overall steepness of the line, there's been no change from the 1L/300m burn rate, even after two trackdays.

oil2.PNG
 
The lower rings are built and designed purposely for the adjustment of ride height they are never fixed :) or if you like to move the unsprung mass to or from the sprung mass.

Adjusting the upper preload rings to adjust height is like using the budget coilovers where you go into "minus" preload to lower the car.
Where you'd run out of preload by hand you'd fit a longer spring not a harder one. Rate changes handling characteristics. Length is depicted by setup. It does affect travel etc but in this case it doesn't matter :)
Again with the opposite you'd fit a shorter spring. But if we use shorter mains we need longer helpers with a softer rate so the load when compressed is the same to maintain the sane handling.
Between 0-5mm of preload is usually recommended as a start point to work with

Agree on the rear that doesn't look fun to adjust :p

You'll have to come over this way one day. It'll be easier to show you using all my fancy contraptions. And all the calculations I have to make to create a base setup and what happens when we vary these settings
 
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pollyp

pollyp

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the way I see it, the difference between a partial threaded coilover and full-threaded coilover is the adjustable hub.

on a partial coilover, the position of the hub relative to the top of the damper body where the bumpstop meets is a fixed distance pre-calculated by the manufacturer to prevent a certain wheel/tyre combo of a certain max size from fouling the body when i hits the bumpstop.

this fixed distance defines the compromise between preventing wheel damage and available bump travel for a specific wheel & tyre size, arch gap, ride height.
if you fit a smaller rolling radius than what the manufacturer predetermined (ie fit a 13" low profile on a setup meant for 15" mid profile), the arch gap would be too big (with the same spring at zero preload), so to reduce the gap back towards the target gap you need to either lower the upper ring beyond zero preload and fit helper spring to replace the slack or fit softer springs, but this reduction in damper shaft height moves it closer to the fixed bumpstop, which as a result compromises bump travel and give a really bouncy ride.

if the rolling radius was severely below the intended design, it may never reach the target arch gap cos the dampers would be resting on the bumpstop (u may as well just have a solid suspension).
the threaded upper ring along with the springs are used to adjust preload and static ride height of the corner.

on a fully threaded coilover, the hub can be adjusted seperately from the damper body to define the best balance between preventing wheel damage & max bump travel for the "actual" wheel/tyre fitted rather than a guessed one-size-fits-all.
the threaded upper ring still works the same as on a partial threaded coilover to define preload & static ride height.

my conclusion is a partial threaded coilover works fine if you stick to the coilover manufacturers recommended wheel/tyre size but if you run beyond the intended spec with bigger/smaller rolling radius and want the bumpstops to prevent wheel damage and utilise all the available bump travel for some comfort for the target arch gap (unless you want zero arch gap = zero bump travel = shattered spine), then a fully threaded coilover is recommended to give full control.

the BC springs have a standardised length and sell assister springs to help reduce ride height if it's too high on a specific spring rate.

if the rear spring adjuster was at the top or built into the damper strut then I'd be more likely to tweak them. tis where enuo's rear spring adjuster prototype comes in :)

found this wiki on the suspension basics I found interesting
http://www.trackpedia.com/wiki/Suspension

I would luv to pop over to urs one day, could take all day (weather, hunger, tea and ability to speak permitting) :cool:
I think one of us will need to bring a white board to JAE for our tech discussion classroom lol :p
 
If you flipped your thoughts over so upper ring to lower ring and vice versa you'd be there :p there's different height "zones" that a particular springs can give you. If you're having to relinquish preload to below zero then your spring is too short. Which is usually the case where larger than designed wheels are concerned. Leaving preload at a set amount, or increasing where necessary and using your lower rings to vary height prevent the problem below (assuming correct springs are used)

but this reduction in damper shaft height moves it closer to the fixed bumpstop, which as a result compromises bump travel and give a really bouncy ride

All springs are designed for the control of sprung mass and as such the coilover is designed to give control over the way that mass is distributed and controlled. Unsprung mass, such as the hub, is controlled by damping primarily. Height is a personal opinion thing too, but can still be balanced whilst higher up but if you set it so that you just touch your bumpstops at max cornering speed/ lateral g-force then that's the correct amount of bump travel. But is only found by measuring with data logging potentiometers and a bit beyond our balancing :p

I could keep writing really long replies but until you see it, it'll be difficult to understand what I mean. At the moment you're using you coilovers in a part threaded manner :)
I'll try do a guide to see if it'll help with a few pics and figures :) all this is avoiding springs rate, compression speed vs force, unsprung mass, damping, alignment etc etc. Corner balancing is only our base setup

He got that design spot on and as I've said before that's the best design I've seen to date

We'll arrange something one day I'm sure. Have a small weekend trek with an event to follow afterwards. That way I wont forget as you can remind me :p

You bring the white board, I'll bring the pens :D
 
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pollyp

pollyp

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If you flipped your thoughts over so upper ring to lower ring and vice versa you'd be there :p there's different height "zones" that a particular springs can give you. If you're having to relinquish preload to below zero then your spring is too short. Which is usually the case where larger than designed wheels are concerned. Leaving preload at a set amount, or increasing where necessary and using your lower rings to vary height prevent the problem below (assuming correct springs are used)

All springs are designed for the control of sprung mass and as such the coilover is designed to give control over the way that mass is distributed and controlled. Unsprung mass, such as the hub, is controlled by damping primarily. Height is a personal opinion thing too, but can still be balanced whilst higher up but if you set it so that you just touch your bumpstops at max cornering speed/ lateral g-force then that's the correct amount of bump travel. But is only found by measuring with data logging potentiometers and a bit beyond our balancing :p

I could keep writing really long replies but until you see it, it'll be difficult to understand what I mean. At the moment you're using you coilovers in a part threaded manner :)
I'll try do a guide to see if it'll help with a few pics and figures :) all this is avoiding springs rate, compression speed vs force, unsprung mass, damping, alignment etc etc. Corner balancing is only our base setup

He got that design spot on and as I've said before that's the best design I've seen to date

We'll arrange something one day I'm sure. Have a small weekend trek with an event to follow afterwards. That way I wont forget as you can remind me :p

You bring the white board, I'll bring the pens :D

this is heavy duty stuff doc.
so much variables to understand n decide.

who's design?

i'll bring an A4 pad cos prob won't have room for big whiteboard n luggage n 4ppl on way home.

yup we need a practical once we meet, give u a prod to remind, but first VVV
 
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pollyp

pollyp

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was gonna take the rear hubs off to fit longer studs n wheel spacers but caliper bolts are seized n rounded :(

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but then prodding around discovered a weak hole behind the sill :rolleyes:

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prodded even more and this! happens:eek:

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ah crap:oops: half the sills back end is rotted, more cost is gonna strain my finance on zero income

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prod the other side

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not as bad but still needs good bit of welding

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rear left calipers leaking

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ah crap need to waste more money:oops:
wish I could afford a MIG
 
this is heavy duty stuff doc.
so much variables to understand n decide.

who's design?

i'll bring an A4 pad cos prob won't have room for big whiteboard n luggage n 4ppl on way home.

yup we need a practical once we meet, give u a prod to remind, but first VVV
It is. I try to explain it so much I confuse myself :p

Enuo's design :)

4 people :O

Shame you're not closer I'd have your sills welded up in no time :)
 
Ouch man! I hope you will sort these problems out. In the future, you will need to get a good micra shell. Did you put waxoil after you bought this micra?


Sent from my iPhone using Tapatalk
 
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pollyp

pollyp

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It is. I try to explain it so much I confuse myself :p

Enuo's design :)

4 people :O

Shame you're not closer I'd have your sills welded up in no time :)

ah yes andy's, I'll have to work it out with him one day on how to match it with my rear springs.

its my m8s stag do, they're popping over on weekend via train, stay over n mess about and I drive em home.

ur in Louth yea? that's bout 3hrs away. hey how bout next weekend I pop down for a chat/suspension lesson while we patch up katherine?
 
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pollyp

pollyp

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Ouch man! I hope you will sort these problems out. In the future, you will need to get a good micra shell. Did you put waxoil after you bought this micra?

looks like it's just that rear arch hidden section and not the visible outer sill or inner sill so seems an easy patch job. indeed I'd like to get a good minimal rust non-sunroof shell to do another swap stuff over job but I dare say if any such thing exist these days, would be super lucky.

I tried the waxoil spray stuff through the floor holes when I was doing the major swap over but tbh doubt it was much help on sills that were already rotting. once it rusts its hard to stop.
now with that rust hole exposed, I could perhaps pop a spray tube along the sill and spray it all.
 
ah yes andy's, I'll have to work it out with him one day on how to match it with my rear springs.

its my m8s stag do, they're popping over on weekend via train, stay over n mess about and I drive em home.

ur in Louth yea? that's bout 3hrs away. hey how bout next weekend I pop down for a chat/suspension lesson while we patch up katherine?
Yea its a good method well worth replicating

I certainly am. I'm only 5mile from cadwell :D
If you're up for it I'll be here. We can get it fixed up :)
 
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pollyp

pollyp

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Yea its a good method well worth replicating

I certainly am. I'm only 5mile from cadwell :D
If you're up for it I'll be here. We can get it fixed up :)

shweet, that's a date :D i'll give ya a prod the day before to remind :p (that sounded abit wrong lol)
 
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pollyp

pollyp

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this sill ain't getting any better. this section was patched n fillered over afew yrs ago and the filler didn't help by trapping moisture

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and poof it crumbles away

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I cut out as much rot away and geez half the rear sill is gone, u ok with rebuilding this Andy? shall I try to make cardboard templates or shall we do it there?

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left sill kinda ok but prob needs the usual cut, cardboard template, weld new piece. the floor edge would also need patching. gonna be alot of work.

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pollyp

pollyp

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all tools packed n ready to go, just missing the kitchen sink.
the ducktape keeping the drizzle off the hole nicely.
 
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