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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Tue Oct 24, 2017 9:25 pm 
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pauly wrote:
If I remember correctly Chris at CG set my car up an inch lower than factory settings on the KW's, the wishbones were parallel to the ground on his rig. I'm confident he knew what he was doing. He rechecked all settings again after a spirited test drive.


I can't remember what the wishbone angle looked like when the car was totally stock in 2012, but when the 3.5 year project was completed in 2016
the ride heights were set to equalise the corner weights @ 260kg each.

I'd say this ride height was approx 40-45mm less than a stock 924S and the bones & steering tie rod were at about 12 degrees from flat.

Image

Settings are one thing, but if any car is lowered from stock the angle will of changed and will make the ball joint end of the bone rise in a quicker arc
(motion) than it did do and hence the body roll will be more than stock and the Roll centre point will of changed for the worst.

Image

Image

There's nothing you can do with any of the Geo to correct this unless the stub axles are modified and the 2 points lowered or shorter body struts are used.

Image

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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Tue Oct 24, 2017 11:05 pm 
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Very pretty. Though as per usual you've conveniently ignored that my wishbones are still parallel to the ground. Goodbye.


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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Wed Oct 25, 2017 9:55 am 
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pauly wrote:
Very pretty. Though as per usual you've conveniently ignored that my wishbones are still parallel to the ground. Goodbye.



No nothing missed here sorry,

If they were flat in standard form your 25mm drop in ride height will of changed the angle to a different one (EG Not flat any more)

Image

There is no way you can change this from any alignment & geometry change of settings so unless they were not flat to begin with ? (for some reason)
or are the K/W struts a shorter body and /or a shorter piston rod / stroke than stock struts do you know?

The later 944 inc S2 & Turbo use a wider wishbone which I think would make the angle change more than the shorter (924s / early 944 version?)

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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Wed Oct 25, 2017 10:04 am 
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A lot of the Racers use the early Steel wishbones modified and box welded for strength which have a bolt on ball pin arrangement.

Longer Ball stem length versions can then be fitted to correct the geometry like these....

Image

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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Wed Oct 25, 2017 11:43 am 
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If you lower the car and tilt the wishbones up that will simulate a loaded case while the car is actually static.
If you then apply the normal load the suspension arm outer connection will travel further up.
But who is dumb enough to lower their car by replacing the springs with a shorter same rate spring allowing for the same amount of suspension travel? Surely one would think that the sills will touch the ground under cornering.

Now...I see some extensive body roll happening on the factory cars under hard cornering, especially the 944 turbos and the early 924s. Surely the center of roll is "not right" during cornering, right?

Obviously if you lower the car but do not limit the suspension travel by the amount you lowered the car, the outer ball joint will travel higher...but if you do stiffen the suspension, the ball joint will NOT travel higher than factory designed.

Of course you loose suspension travel and that can mean less grip but the point is you will not roll the car if you lower it and limit the upwards suspension travel by increasing the spring rates and upgrading the sway bars.

There is obviously a limit of lowering the car vs suspension travel limit..meaning if you lower it too much you will need zero suspension travel not to go outside of what the factory allowed to happen with the original setup. But what the factory considered OK for heavy cornering is quite a lot...because the cars were designed to go on really rough roads as well so there is maybe 3 times the amount of suspension travel needed today for most applications of the 924/944.

So...bottom line, as long as you don't push the wheel more than the factory into the arch under load you're fine..at least for street driving as these are ultimately street cars...not race cars.


Image

Image

Image

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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Wed Oct 25, 2017 6:01 pm 
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Quote:
morghen
If you lower the car and tilt the wishbones up that will simulate a loaded case while the car is actually static.
If you then apply the normal load the suspension arm outer connection will travel further up.

If you lower a car the negative performance loss that the suspension lower arm's angle has changed does not simulate that it's loaded,
but instead that it's pivot point (Roll centre - see drawings on previous posts) has been changed to a position that it's angle and the arc
that this arm now moves (from it's resting position) is no longer optimum as designed and set by Porsche, hence the arm produces more Roll than standard.




Quote:
morghen
But who is dumb enough to lower their car by replacing the springs with a shorter same rate spring allowing for the same amount of suspension travel? Surely one would think that the sills will touch the ground under cornering.

All lowered spring kits produced and sold have increased spring rates, I'm not aware of anyone that makes lowered springs that are the same spring
rates as any OE Porsche transaxle?



Quote:
morghen
Now...I see some extensive body roll happening on the factory cars under hard cornering, especially the 944 turbos and the early 924s. Surely the center of roll is "not right" during cornering, right?

The Roll centre "is right" as Porsche have calculated and intended on stock cars. It only get worst (as does the bumpsteer) and creates an incorrect angle
and (roll centre pivot position) when the car is lowered.



Quote:
morghen
Obviously if you lower the car but do not limit the suspension travel by the amount you lowered the car, the outer ball joint will travel higher...but if you do stiffen the suspension, the ball joint will NOT travel higher than factory designed. Of course you loose suspension travel and that can mean less grip but the point is you will not roll the car if you lower it and limit the upwards suspension travel by increasing the spring rates and upgrading the sway bars.

If you lower the car the ball Joint end of the wishbone is raised, the only way to stop this is with shorter dampers or raise the top mount and fit it above the turrets
and also fit modified stub axle extensions to connect the 2 pivot points (wishbone & tie rod) lower down.


Quote:
morghen
There is obviously a limit of lowering the car vs suspension travel limit..meaning if you lower it too much you will need zero suspension travel not to go outside of what the factory allowed to happen with the original setup. But what the factory considered OK for heavy cornering is quite a lot...because the cars were designed to go on really rough roads as well so there is maybe 3 times the amount of suspension travel needed today for most applications of the 924/944.

You can lower a car as much as possible as long as the mechanical parts can be modified and corrected, any car designed to cope with all road conditions
can still have the same amount of travel with modified components but with a lower ride height to reduce the centre of gravity and increase cornering G forces.


Quote:
morghen
So...bottom line, as long as you don't push the wheel more than the factory into the arch under load you're fine..at least for street driving as these are ultimately street cars...not race cars.

The bottom line is no aftermarket suspension company (selling shocks and springs) will advertise or inform any prospective buyer that their car will handle worst unless major changes are made! In reality most stiff lower suspension kits are so much stiffer than standard set ups and more often than not people tend to replace worn
original suspension for stiffer then the difference becomes so much more stiffer than it's this that to most feels like a big improvement.
However others are more sensitive, skilled and aware that there is something adverse and they will want to rectify this and improve it. Racers will put up with far more uncomfortable and adverse characteristics than the average road user.

A very high percentage of people fitting lowered springs and / or Dampers are looking for a "look" just in the same way as fitting "Wheel Spacers" and bigger diameter wheels and narrow sidewall tyres etc.. It's an Industry led by "persuading" buyers this is the way to go for Race performance on the road but it's not that clear cut.

Many lowered and especially incorrectly fitted offset wheeled cars are far more unsafe and difficult to control than standard cars.

Fitting all of the above parts to correct the Roll centre and eradicate the Bump steer on project 924srr27L has greatly improved the safety and cornering abilities
on public roads. You can have a lowered car that's works perfect, but most people are not fussed about the handling only the look. Most of these people are not "drivers"
but more into the show and polishing scene etc..

I know of many racers that are either not aware of this issue or like a few others for some reason are not convinced or understand it.

It's a huge benefit that is possible to be had if people are such inclined, but it's not something that is easily obtainable or cheap to remedy as not that many solutions
are currently available to buy worldwide.


R

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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Wed Oct 25, 2017 9:47 pm 
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I love this discussion. Car suspension is always a compromise unless it's a fully committed race car then it's lap time regardless, (unless it make the car undrivable for the person that drives it)
The balance of controllablity (handling) and corner speed varies from circuit to circuit and bend to bend. In the real world we want a car that is predictable and doesn't bite us back if we get it wrong ref. lift off oversteer on old 911s. Driving style varies, some prefer a tail happy car whilst others hate to get in an opposite lock situation. Some can drive anything. Some are so insensitive they don't notice = slow.
We are fortunate in having cars that handle better than most, it's when you start playing with it that you can cock the whole thing up. One alteration here affects something elsewhere and often negates the original intention. Even F1 seem to get a bit lost sometimes.
924srr27l has done his homework and the outcome is laudable.

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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Wed Oct 25, 2017 10:52 pm 
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Endoman wrote:
I love this discussion. Car suspension is always a compromise unless it's a fully committed race car then it's lap time regardless, (unless it make the car undrivable for the person that drives it)
The balance of controllablity (handling) and corner speed varies from circuit to circuit and bend to bend. In the real world we want a car that is predictable and doesn't bite us back if we get it wrong ref. lift off oversteer on old 911s. Driving style varies, some prefer a tail happy car whilst others hate to get in an opposite lock situation. Some can drive anything. Some are so insensitive they don't notice = slow.
We are fortunate in having cars that handle better than most, it's when you start playing with it that you can cock the whole thing up. One alteration here affects something elsewhere and often negates the original intention. Even F1 seem to get a bit lost sometimes.
924srr27l has done his homework and the outcome is laudable.


Thankyou,

Yes I love it too.... and for sure it's (Suspension settings) a compromise for road because they are so varied (tarmac quality, cambers and bumps) and the weather conditions. I've had a very difficult job to sort the car because most of the "off the shelf" components are semi track based and far too hard for a 1 ton car.
Hence the only way was to have dampers made but even then I've currently found the best damper settings are front 15 from 40 clicks and the rear 12 from 50 which just show how soft they work best on the road for me and how much stiffer they will go should I want more for trackdays etc...

Yes F1 are at least lucky these days that everything is measured, monitored and this usually means they can find any issues far quicker
than the 1970's when they didn't have computers and sensors plugged in them so like me and my testing, research and modifications I can only go by the seat of the pants feel.

I've no computer technology installed (Yet) but I'm very confident with my knowledge of knowing what feels better or worst from a reasonable amount of National Racing success over 2 decades also various careers in road & race tuning, shock absorber management, technical presentations, driving instruction in the USA and F1 & WRC roles etc.. all help understand and decide what is working and what's not.

But it's a subject like many which has plenty of scope to never stop learning more and more.

R

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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Thu Oct 26, 2017 1:34 am 
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Endoman wrote:
924srr27l has done his homework.



I hope half term is over soon....


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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Thu Oct 26, 2017 9:46 am 
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Elephant Racing do list a fair amount of components for the Transaxle cars, and if anyone was to make more in regard
to wishbones for lowered car's they would probably be the company to make them but as ever the 911 has more available...

https://www.elephantracing.com/porsche/991/adjustable-control-arms-and-links-for-991/

R

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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Thu Oct 26, 2017 4:49 pm 
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Given up posting on PCGB ??? Wonder why

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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Thu Oct 26, 2017 6:59 pm 
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Waylander wrote:
Given up posting on PCGB ??? Wonder why


Not at all, regular updates have been posted on project 924srr27l throughout October, as have several other posts been contributed to.
I only post on subjects I'm interested in learning about, unlike a few selective others.

Maybe I should join the 968 forum, is it any good ?


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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Thu Oct 26, 2017 8:10 pm 
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Be my guest, we only discuss 968’s

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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Thu Oct 26, 2017 8:57 pm 
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Waylander wrote:
Be my guest, we only discuss 968’s



Excellent, same chassis as a 924, a 944 S2 engine with a different head and plastic skirts on the front and rear....

I wonder how close the 944 S3 tag was set for production ? I guess a facelift and new number was always going to sell better than the same model
with an updated prefix but even then they were so expensive and struggled to sell. Good job the marketing dept. came up with the idea to reduce the price by a fair chunk, add some bucket seats and add the CS moniker..........the rest is history and now ironically the more expensive Coupe is worth less than the cheaper CS was to buy at the time!

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 Post subject: Re: What did you do to your 924/944/968 today?
PostPosted: Sun Oct 29, 2017 10:07 am 
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+1 on the 968 forum :D

For today, my 968 wouldn't start :( almost no tacho movement at all at first.... Then a slight cough to start, then some tacho movement around 800rpm but no sign of life... Sparks or fuel just need to find which one :lol:

Found a rear footwell of water as well yesterday :evil: damn sunroof drains - it's leaking between the pipe work and the body.... Out with the strimmer line and silicone sealant then... Either that or a length of hose pipe to replace the aged plastic. Wish me luck :wink:

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