How low can you go..?!

appletonn · Sep 11, 2009

Having covered almost 1000 miles now in the last 4 weeks, whilst running the engine in, I've come to the conclusion that the RS ride height is too low for both the typical bumpy B road and the standard 964 front suspension - by standard, i mean steering arms and uprights, no sexy 993 RS uprights etc.

Spoke to Chris Franklin at Centre Gravity this week and he advised that really you don't want to go lower than RS + 5mm, and preferably + 10mm, even on KWs.

The car feels slightly too 'muscle bound' if that makes any sense and still doesn't quite flow with the road as well as it could.

I am seriously tempted to book a session with him, as I've read only positive things about people's experiences and the vast improvements to their cars' feel and handling following a session with him.

He charges £250 plus VAT, but that could well be the best £250 I'll spend on my car.

I think the remap will have to wait, as I want the handling and feel to be right more than a few extra horses.

Dave Wilkinson · Sep 11, 2009

Nick,

When Chris set my C4 up we came to the same conclusion. Down at the RS level the standard cars tend to suffer from bump steer due to the angle at which the steering arms settle. In an ideal world, the steering arms should be level to the ground with the car in it's neutral state. When it's lowered beyond it's designed height, the steering arms will slope upwards from the rack to the hub, such that upward movement of the wheel (say, over a bump) will cause the effective steering arm length (due to the radius of the arc of the suspension) to shorten slightly, giving a non-intentional steering input to the hub.

We settled on RS + 7mm for mine and it seems to work OK. If you've not been to Chris before, make sure you take your travel pills in preparation for the test drive!!! I'll say no more!!

Regards

Dave

appletonn · Sep 11, 2009

ORIGINAL: Dave Wilkinson

Nick,

When Chris set my C4 up we came to the same conclusion. Down at the RS level the standard cars tend to suffer from bump steer due to the angle at which the steering arms settle. In an ideal world, the steering arms should be level to the ground with the car in it's neutral state. When it's lowered beyond it's designed height, the steering arms will slope upwards from the rack to the hub, such that upward movement of the wheel (say, over a bump) will cause the effective steering arm length (due to the radius of the arc of the suspension) to shorten slightly, giving a non-intentional steering input to the hub.

We settled on RS + 7mm for mine and it seems to work OK. If you've not been to Chris before, make sure you take your travel pills in preparation for the test drive!!! I'll say no more!!

Regards

Dave

Hmmm, I've read various reports about the test route and the famous roundabouts, so I'll take the right pills with me!

It's not necessarily that I'm experiencing bump steer especially, but more that the car just feels too restricted in its movements, can't really put it any better than that!

I know it's a drastically different driving experience from my old 944 turbo, but it just doesn't yet feel as good as i know it could be.

Booked in with Chris for 3rd week in October, so hopefully should be on top form in time for Curborough![

]

graham harvey · Sep 11, 2009

Hi Nick,

Can you confirm that the £250 price is correct? If so, i'll book. I thought it was nearer £500. I've just KW3's fitted along with front/rear wishbone and anti roll abr bushes replaced to powerflex items. The difference was amazing, however I am a little unsure, now it's all settled, if it needs a little 'tinkering' with.

Steve Brookes · Sep 11, 2009

I know Chris quite well now, even though he's yet to do any adjustments for me. Chris thinks my car (being at RS ride height) is too low - cheeky sod got under my car and measured it without my permission! [

] I agree to differ with Chris and always have some good banter with him about it.

What I think you have to remember is that there is NO perfect compromise for road and track. For me the RS specs give it the track biased settings that I want. Saying that I think the road manners are extremely good and probably more friendly than a true RS because KW3s are no where near as stiff as RS springs and shocks. I get a little bump steer when the petrol tank is full which gets less noticeable as fuel gets used up (Nb. height should never be set on a 911 if the fuel is low). But apart from that I think the car flows beautifully on the road. Especially through fast bends. However, I'm comparing to a car that was obviously badly set up on tired suspension to one on new suspension and geo.

BTW while you're there invite Chris and Jane along to Curborough to say hello...it's not far from them and there will be plenty of potential customers for them to chat to. [

]

appletonn · Sep 11, 2009

ORIGINAL: graham harvey

Hi Nick,

Can you confirm that the £250 price is correct? If so, i'll book. I thought it was nearer £500. I've just KW3's fitted along with front/rear wishbone and anti roll abr bushes replaced to powerflex items. The difference was amazing, however I am a little unsure, now it's all settled, if it needs a little 'tinkering' with.

Well, i thought nearer to £500 too, but he quoted me £250 plus VAT.

appletonn · Sep 11, 2009

ORIGINAL: Steve Brookes

I know Chris quite well now, even though he's yet to do any adjustments for me. Chris thinks my car (being at RS ride height) is too low - cheeky sod got under my car and measured it without my permission! [] I agree to differ with Chris and always have some good banter with him about it.

What I think you have to remember is that there is NO perfect compromise for road and track. For me the RS specs give it the track biased settings that I want. Saying that I think the road manners are extremely good and probably more friendly than a true RS because KW3s are no where near as stiff as RS springs and shocks. I get a little bump steer when the petrol tank is full which gets less noticeable as fuel gets used up (Nb. height should never be set on a 911 if the fuel is low). But apart from that I think the car flows beautifully on the road. Especially through fast bends. However, I'm comparing to a car that was obviously badly set up on tired suspension to one on new suspension and geo.

BTW while you're there invite Chris and Jane along to Curborough to say hello...it's not far from them and there will be plenty of potential customers for them to chat to. []

Absolutely Steve, but I think the RS alignment with slightly raised ride height (5-10mm is not much) but retaining the slight downward rake will allow the dampers to work better whilst still retaining the 'iron fist' damping control.

I think that slight increase in height will allow me to tighten up the rebound settings slightly too.

Steve Brookes · Sep 11, 2009

Nick, I agree that such small adjustments will make it better for road use and still pretty handy on the track. I get the impression that as soon as the phrase 'going on track' is mentioned to Danny you will get the nearly full fat track set up. A set up that he would put on if he were to use the car on track himself (I believe he's pretty handy behind the wheel). I guess when you picked the car up he mentioned things like, "you'll get some wheel rub on lock but that's to be expected when it's set up for the track". As I say Danny's set up feels spot on to me but I'm coming from a poor set up and you're coming from a well setup, totally different car.

Chris will mostly charge by the hour. With your new and recently geo'd suspension everything will come undone easily (I'm guessing this will also apply to Graham's car). Hence he can keep the price down to £250. It's the ones that haven't been adjusted for 5, 10 or 15 years that take the most time. And I agree that you'll get full value for money out of Chris [

]. It will then be interesting to trade passenger rides at Curborough [

]

p.s. Well done on getting a free swap with John Boggiano's RS door cards..you lucky.....!

polar964 · Sep 11, 2009

It will be the best £250 you've ever spent on your car. You may well pay £250, but you'll have had well more than that in time, commitment and attention to detail. Chris doesn't do, near enough or just about, he gets it right. I'm sure you won't be disappointed

appletonn · Sep 12, 2009

ORIGINAL: Steve Brookes

p.s. Well done on getting a free swap with John Boggiano's RS door cards..you lucky.....!

Yes, can't quite believe it myself!![

]

appletonn · Sep 29, 2009

James, from my conversation with Chris, he will set the car up to suit its intended purpose. I want mine for fast road/occasional track work so he has suggested that RS height is slightly too low for our bumpy B roads and may indeed stop the dampers working properly as there is not enough damper stroke.

From what I know of his work, he sets the car up to his advised spec and then test drives it until he is happy with its responses at speed.

Looking forward to it!

appletonn · Sep 29, 2009

ORIGINAL: slider

Nick, I meant the other specs other than just chassis height. Lowering is all very well but caster angles, toe angles and camber angles have a big effect on how the car feels as it enters transitions and exits the corner. As you know the P car chassis' are very adjustable, I am in the middle of trying to set mine up for the quite bumpy roads now encountered in NZ and have just found that a simple change of just 1.7mm of toe on the rear has had a quite dramatic effect on straight line stability (plus) and corner exit oversteer (also plus unfortunately). Rather than spend a month twiddling I hoped an expert chassis man might be able to give some guidance. Do you think he would divulge.?
Kind regards
james

Well I asked him over the phone about a good starting point for the bump and rebound settings on my KW set up and he was happy to give me his advised settings, so I'm sure he would do the same for the camber and toe etc.

Dave Wilkinson · Sep 29, 2009

James,

As Nick has said, Chris is extremely flexible in that he will use his huge experience and knowledge to set the car up for whatever your intended use is likely to be.

The way he works is to measure the existing setup and, based on that and the observed tyre wear patterns, he'll conclude why the car currently handles the way it does. Then, he will make a decision on each of the adjustable parameters as to what needs to change how and do it. The secret, if there is one, is to know precisiely how each adjustment, in combination with the others impacts the handling. This is where Chris excels. Pretty much any spanner monkey can adjust the geometry but it takes great skill and expertise to know the effects of each adjustment.

Knowing how accomodating Chris is I'm sure he would be only too willing to give you some advice either by phone or, probably preferably via e-mail. He is on info@centergravity.co.uk.

Regards

Dave