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kyepan

How Not To Modify Your 205's Suspension...

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B1ack_Mi16
The height of the front inner wishbone point would be very nice if you could get it!

 

Or just measure the wishbone angle when car is sat level.

 

Heights will differ a little bit depending on what tires it's sat on.

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Cameron

True.. but the wishbone angle is more likely to be inaccurate, it takes a very small fluctuation in angle to give a large fluctuation in height. Maybe measuring the inner wishbone point height and the tyre rolling radius would be better?

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kyepan

even arch to wheel clearance would be a good relative indicator to standard.

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martyn180
even arch to wheel clearance would be a good relative indicator to standard.

 

Checked mine yesterday funnily enough, as put new springs on.

Front 25"/Rear 24" from the floor, vertical through the centre of the wheel to the bottom of the wheel arch moulding.

on .1 9 gti Speedlines, with 185/55 15

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kyepan
Checked mine yesterday funnily enough, as put new springs on.

Front 25"/Rear 24" from the floor, vertical through the centre of the wheel to the bottom of the wheel arch moulding.

on .1 9 gti Speedlines, with 185/55 15

thank ye very kindly!

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welshpug

I took these wonderful pictures last night but forgot to measure the ride height :)

 

 

 

4675576043_8de609f492.jpg

 

4676193808_f0ab47f73c.jpg

 

 

but I do have this from the rally build book;

 

ptschallenge205309rideheight.jpg

 

 

I have no idea how they arrived at those figures, but they are lower than standard by about 25-30mm IIRC.

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engine killer

Dear all,

 

After seeing Graham's post regarding sleeving the hub http://forum.205gtidrivers.com/index.php?s...21487&st=10 , I am now thinking to fabricate an extension to the clamp (balljoint pickup) to reduce the roll couple.

 

The top side will be a solid round cylinder shape with diameter of 18mm (and boring the clamp to 18mm is necessary) and the bottom side will be same dimension/shape as the hub's clamp. The top side will be welded to the original clamp.

 

This will move the clampinng point roughly 25mm lower.

 

But it seems like when the car's center of gravity is lowered by say 25mm, the roll center will be lowered by much more than 25mm. I can hardly get access to a proper hoist to measure all the required measurement, so, how much shall be lowered?

 

Most importantly, do you guys think it is workable? Anything I have to take into consideration when fabricating the extension?

 

For the bump steer issue, I think I will do something similar to those aftermarket kits as they are already safe to run provened.

 

Any comment and suggestion are mostly welcomed.

 

Thanks

post-4860-1278399305_thumb.jpg

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Cameron

Personally, I wouldn't do it. Using rod ends in bending is bad enough, but using a spacer to lower the mounting point is going to put some very large bending moments into the spacer. If you then beef up the spacer it will be the hub that has to cope with the huge forces and you may well have problems with that ovalling.

 

Also you may be lowering the roll centre slightly, but that doesn't necessarily mean you'll see a matching reduction in load transfer, since that is made up of moments about both the roll centre and at ground level. You will reduce it somewhat but the results will more than likely be less than you'd expect, and could well mean it isn't worth the effort in the first place.

 

The largest benefit you'll get in my opinion would be greater camber compensation as you'll be returning the wishbone towards it's normal angle, but I reckon the gains in negative camber won't be sufficient to overcome the tendency towards positive camber change with roll that is inherent in the 205's McPherson strut design. Again you may find that the benefits are too small to notice, and / or aren't worth the hassle of designing your product to overcome my first point. You may find that you get more than adequate results by simply increasing the static camber, providing you don't go to any silly extremes.

Edited by Cameron

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engine killer

Thanks for your valuable advice Cameron.

 

In the past few days I have been surfing the internet regarding the "bump steer kit" and "roll centre adjuster".

 

Both roll centre adjuster and bump steer kits from different brands are more or less the same.

 

For Whiteline, they are more on having a much taller balljoint instead of adding spacer.

 

For the bump steer kit, I may have a go and try. The bolt going through the rod-end will be much thicker since I have to bore the hole on the hub to same diameter, hope this will strenghten a bit.

 

And the roll centre..... since there aren't many 205 in Hong Kong and I surely won't spare my money on a new pair of hub (if the trial one failed), so unless I am lucky enough to get a cheap second hand hub, otherwise no go/try.

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kyepan
but I do have this from the rally build book;

ptschallenge205309rideheight.jpg

 

I have no idea how they arrived at those figures, but they are lower than standard by about 25-30mm IIRC.

 

hey welshpug,

i'm going to measure and reset the height of the coilovers at the front today, when you say arrived at those figures... which ones are standard in your eyes?

looking at other posts i've just answered my question yet again

332-325 = standard front height.

 

thanks again (and for the advice about the valve springs)

 

Justin.

Edited by kyepan

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welshpug

They're straight from the rally build book (inc the hand written ones!) Minimum ride heights for the challenge and GPA or N cars in various guises, I'm sure I have the 309 ones somewhere too.

 

I'm afraid I never got round to measuring the height of a "standard" car.

Edited by welshpug

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kyepan
They're straight from the rally build book (inc the hand written ones!) Minimum ride heights for the challenge and GPA or N cars in various guises, I'm sure I have the 309 ones somewhere too.

 

I'm afraid I never got round to measuring the height of a "standard" car.

mine tally very closely to the specs quoted above, will have a look at a couple of photos of a standard car and see if i can guess the height.

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welshpug

actually I do have a standard 309 now, I can can see how close the figures are there, I do remember the figures being lower than standard but not drastically.

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kyepan
actually I do have a standard 309 now, I can can see how close the figures are there, I do remember the figures being lower than standard but not drastically.

had another good hunt about for the standard figures last night! still no joy :)

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welshpug

right, standard 5 door 309 Goodwood (aka gti with leathers)

 

 

(front struts known o.e, rebuilt rear beam at a guestimate ride height)

 

front arch 360 mm, front jacking point on worn 195-50's, 19.5cm.

 

rear arch 320 mm, rear jacking point on worn 195-50's 21.5cm.

 

So a 20mm rake front to rear, 40mm difference the other way in the wheelarches, which tallies in with the minimum heights front to rear of the rally build book, which would be 35mm lower than standard, but quite significantly higher on spring rates (and run underbody protection!)

 

 

It handles great even on 8 year old s*ite tyres :(

Edited by welshpug

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lukesaddy

my last car (106) was lowered 50mm at the front and 100mm at the rear and the back end had no suspension travel and slipped and slid when cornering (even with T1-r's)

 

the front used to turn in well though.

 

whats the best amount to lower a 205 1900 gti ?

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welshpug
slipped and slid when cornering (even with T1-r's)

 

:)

 

 

 

whats the best amount to lower a 205 1900 gti ?

 

 

not at all :P

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lukesaddy

ideal,

 

just out of curiosity (i know its not related) but whats the OEM tyre size on 15" speedlines ?

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oli-pug
ideal,

 

just out of curiosity (i know its not related) but whats the OEM tyre size on 15" speedlines ?

 

185/55

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lukesaddy

thanks a lot mate :huh:

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kyepan

an update, soon with photos to follow.

 

In brief - raised front 30mm... not a massive deal of difference, except it rode the bumps more prodigiously.

 

reset the rear anti roll bar so it was not causing the right side to dip, and gave it a quarter turn of toe in on the left.

 

difference, not as sharp on the turn in, but directional stability, and more importantly predictability went up a great deal.

 

Next, rear raising to standard, and find the clunk (think it's the right track rod end bolt that's not seated.

 

J

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welshpug

having the front higher than than back will dull turn in, fingers crossed raising the rear will restore it :P

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kyepan

Prior to raising

4852474351_5db8e1d9e7.jpg

 

Post raising.

4852474825_47153855f6.jpg

 

raising amount, from the rusty bit up.

4852474587_e95ffd4004.jpg

 

on it's feet

4853095948_3787228f47.jpg

erm.. may have washed it, polished the wheels and put stuff on the trim... also popped the dent out of the door

 

as compared to a golf

4853096170_805175b407.jpg

Ball.

 

 

as compared to .. no wait, this is a harris hawk, and he's in my work car park with bob.. harris hawks hate pigoens

4852475711_2cb6d18fcb.jpg

:D

 

Cheers

 

J

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kyepan

So have done some more testing today, track rod end was fine, where the clunk is coming from I'm not sure.

 

Secondly - the car is still pulling across the road under ... hard acceleration if it hits gets near the crown of the road, or diving to the left if it hits a pot hole, however the steering wheel turns too in both instances, so this just seems to be torque steer and the wheel going into a bump.

 

Need to sort the tracking better.. will do that soon.

 

Where it's not so good is into long period dips at 60mph plus, at this point because it's not hitting the bump stops in the compression, it's really building up energy and kangerooing off them.. Quite un-nerving..especially over motorway bridges where you get the change in road surface combined with a crest.. perhaps a touch more damping is needed.

 

Also the right rear bump stop is gone, so, this cannot be helping, especially if it hits the bumpstop on one side, and the other keeps going, at this point it would think it's rolling and the ARB would load up, then unload afterwards

 

The car also feels more alive under breaking, would not say there is much more dive, but modulation of the pedal is easier if the fronts do get a bit closer to the limit, perhaps again because it's not running on the stops all the time.

 

The neutral dynamic of the set up is still there, so in flat level cornering lift and the back gently goes, apply power and it bites, subjectivly the grip seems more accessible.

 

The LSD itself is now more noticable, you can point the wheels a bit more and just plant your foot mid to late corner and it goes where you point it, i will assume the negative camber is now working properly.. but i could be wrong.

 

 

Next tracking

 

Then test

 

Stiffen shocks slightly for the longer period bumps.

 

Then test

 

Bumpstop.

 

Then test

 

Raise the rear.

 

and we can see from there

 

A foot note about shocks, i can now see why shocks that are adjustable for both fast and slow bumps are a great idea, when ever i get a setting that works for longer duration stuff, it's too stiff for the minor surface changes and crashy on the little stuff. Pay your money... get your dampers.

 

J

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kyepan

Another update, so the car has been run for about three weeks with the back low and the front high, in summary it's much less likely to spit you into a hedge.

 

Did stiffen the shocks by two clicks, so am on 18/40 on both front and rear, this did sort the longer bumps to a certain extent, but at the rear it still bounced out of time with the front.

 

Paul helped me raise the rear, which took us an astonishingly short 1 hour, and that's from jacking it up to putting it down.

 

Will make sure that a couple of pictures and actual measurements are up soon, but the initial evidence suggests, it is not only very planted, but now much smoother to drive, Riding bumps well.

 

The specific test over the motorway bridge seems to work even better with the rear up, it now glides over it.

 

We still need to look into tracking, but what ever it's set to is clearly working well, as you can steer, apply power, and the diff drags you in that direction. Much easier to drive than before.

 

Cheers

J

 

Will report back with some figures for the actual ride heights, but as a driver, i have bags more confidence in placing the car and it staying there. The steering feel has changed somewhat, perhaps more linear.

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