Lowering an SC
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bones
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Lewis bearing in mind that SCs were hand finished and body tolerances less rigid than current Porsches you should generally be able to fit wider rims to an SC and lower it without hitting anything. I have 17" 7.5' fr & 9" rears on mine with no problems. Ride height is currently standard. I plan to lower it soon but I can't go too low as I have a front splitter fitted. Lowering the front is quick and easy about 30 mins. Lowering the rear is much more comlicated and involves about 2 hours (optimistacally) work. Plus you need a lift to do this work or some high axle stands. Read up on this as much as possible beforehand.
I have lowered my car by about 30mm with no problems at all. You need to get the tracking re set at the front. On the rear if you have the adjustable arms, you can with luck re set the height with out removing the trailing arms. As bones said the rear can be tricky especially if you have to remove the spring plates and reset the torsion bars as you will need to reset the whole rear suspension geometry which only Porsche specialists are up to. This can take up to 8 hours labour with a corner balance as well. Is it worth all the trouble and expense?you bet the car wil handle so much better especially if you get the pro alignment afterwards
Bruce
83 sc
Bruce
83 sc
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Bones
So what are the standard settings (Height and geometry)?
At last (after a saga) I have the new correct Sport shocks fitted, new A Arm bushes, front sway arm bushes, Turbo Tie Rods and strut brace. The geometory was set yesterday to be "standard" road height, however I feel that the front height is on the high side. Hence the question what is standard?
See you at Brans Hatch.
Cheers
SobeUK
So what are the standard settings (Height and geometry)?
At last (after a saga) I have the new correct Sport shocks fitted, new A Arm bushes, front sway arm bushes, Turbo Tie Rods and strut brace. The geometory was set yesterday to be "standard" road height, however I feel that the front height is on the high side. Hence the question what is standard?
See you at Brans Hatch.
Cheers
SobeUK
bones
New member
I'm interested to know how you fitted A-arm bushes, what bushes did you put back in there?
Standard ride height is measured in different ways, for the factory way of setting the ride height you have to take a variety of measurements to achieve the correct ride height, some folks dont use this method (I would) and just measure from the floor to the top of the wheel arch. The front height is 105mm above the centre of the torsion bar and is easy to do. The rear height has the wheel centre 16mm below the the centre of the torsion bar cross tube. Setting the rear ride height is an 'involving' process! A 1º change in torsion bar inclination amounts to 7-9mm change in ride height. On a standard SC you can afford to lower it about 4cm or so but remember the whole car has about a 1º inclination upwards rear to front, I don't know how this is measured or if it's a visual trick. You can buy fully adjustable rear spring plates including the torsion bar bushes for about £200.00
http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_SUSprf_pg24.htm#item
Standard ride height is measured in different ways, for the factory way of setting the ride height you have to take a variety of measurements to achieve the correct ride height, some folks dont use this method (I would) and just measure from the floor to the top of the wheel arch. The front height is 105mm above the centre of the torsion bar and is easy to do. The rear height has the wheel centre 16mm below the the centre of the torsion bar cross tube. Setting the rear ride height is an 'involving' process! A 1º change in torsion bar inclination amounts to 7-9mm change in ride height. On a standard SC you can afford to lower it about 4cm or so but remember the whole car has about a 1º inclination upwards rear to front, I don't know how this is measured or if it's a visual trick. You can buy fully adjustable rear spring plates including the torsion bar bushes for about £200.00
http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_SUSprf_pg24.htm#item
There was an article in January 2004 issue of "911 & Porsche World" covering this subject, with pics.
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You can get A-Arm bushes from Type911 (£48 for a set of four). I had Xavier Autos fit them while he was fitting the new struts etc. They are also available in the USA from Pelican.
Took the car for a spin on Sunday and wow what a difference. She is like a different car now since the Turbo Tie Rods, A Arm bushes, Sway Bar bushes and struts.
The road height deffinatly looks a bit high. Will have to measure it some time. The current height will have to do for the festival.
See you there[
]
SobeUK
Took the car for a spin on Sunday and wow what a difference. She is like a different car now since the Turbo Tie Rods, A Arm bushes, Sway Bar bushes and struts.
The road height deffinatly looks a bit high. Will have to measure it some time. The current height will have to do for the festival.
See you there[
]SobeUK
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New member
I think you mean that the rake is one degree nose down rather than the way you describe it, which is nose up.
I am curious as to what the mixed reports are on lowering. What have you heard Lewis? There are a couple of things to be mindful of. Most obvious is clearance. Speed humps and steep driveways become an issue and require extreme caution, very low approach speeds and a diagonal angle of attack - but I have all of about 100mm of front clearance which is lower than most people go. You can run out of shock travel if you go really low and don't trim the rubber bump stops. You can also increase bumpsteer if you don't raise the steering rack with rack spacers - but in my experience you have to go pretty low before it is a problem. Final issue I can think of is the possiblility of wheel clearance issues, but you would need big wheels and tyres and to be very low.
Ultimately it is a question of personal aesthetic preference. IMHO, lowering by say 20mm has no real downside and looks great. Lowering much more than that becomes a little more difficult but is still no big problem. I would not recommend the Sway-a-way adjustable spring plates because they have plastic bushings that will squeak and drive you crazy (ask me how I know). Go to a race shop who are used to lowering, indexing torsion bars and corner balancing cars. They will do it quickly and will save you money. I would replace the rear spring plate bushings with Neatrix rubber bushings while the spring plates are off. This is a job that 99% of SCs and older cars would benefit from. It is the key location point for the rear wheels and the old rubber bushings wear a lot. It makes a huge difference to toe and camber control. If you want a nice fast road upgrade put a set of turbo 26mm torsion bars in there while you are at it.
Richard
bones
New member
Of course I do! [
] Even replacing the old torsion bars with new standard ones will make a noticeable improvement to the handling as they are probably shot by now if the car has any appreciable mileage on it. A common choice for SC torsion bar upgrade is 21(22)fr & 26(27)r. If you are doing a complete suspension refurbishment remember to renew the drop links, the anti roll bar fastenings and bushes and the trailing arm bushes.Hi,
In the end, I went for a 20mm lowering all round.
I took my car to Tuthills to be corner weighted and lowered.
Francis advised that the kind of gains you get from a moderate lowering is basically aesthetics only, as there are far better mods for handling - i.e. tyres.
I had to admit that the main reason for lowering was for a more purposeful stance and it does look a lot better, even with just the 20mm lowering. Having the car corner weighted made loads of difference to the handling, it now feels a lot more 'chuckable'.
When lowering my car, the 1% of rake was maintained. However, the gap from the top of the tyre to the wheel arch appears larger on the front than the rear - Francis advised this is because of the height of the wheel arch - the actually body of the car does maintain the 1% rake.
At Lemans this year, I was talking to a guy who also had an SC (sorry, I've forgotten your name if you're reading this) and his had been lowered quite a bit further than mine and he reported no problems fouling speed bumps etc - It also looked very good like that. So basically, I think I will take mine a bit further, but not before a full underseal, new front pads etc etc....
Incidentally, to lower my car I don't think they even had to touch the torsion bars, they just used the factory adjustment bolts.
Hope that helps.
Lewis.
In the end, I went for a 20mm lowering all round.
I took my car to Tuthills to be corner weighted and lowered.
Francis advised that the kind of gains you get from a moderate lowering is basically aesthetics only, as there are far better mods for handling - i.e. tyres.
I had to admit that the main reason for lowering was for a more purposeful stance and it does look a lot better, even with just the 20mm lowering. Having the car corner weighted made loads of difference to the handling, it now feels a lot more 'chuckable'.
When lowering my car, the 1% of rake was maintained. However, the gap from the top of the tyre to the wheel arch appears larger on the front than the rear - Francis advised this is because of the height of the wheel arch - the actually body of the car does maintain the 1% rake.
At Lemans this year, I was talking to a guy who also had an SC (sorry, I've forgotten your name if you're reading this) and his had been lowered quite a bit further than mine and he reported no problems fouling speed bumps etc - It also looked very good like that. So basically, I think I will take mine a bit further, but not before a full underseal, new front pads etc etc....
Incidentally, to lower my car I don't think they even had to touch the torsion bars, they just used the factory adjustment bolts.
Hope that helps.
Lewis.
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I think this is really conservative on the rear sizes and will give you too much understeer. The spring rate increases to the 4th power of the diameter (or so I am told) so you can work out the relative stiffness if you have the original spring rates (search on Pelican will reveal them), but the common resizings are IMHO, 21/27, 22/28 and 22/29. These are all pretty close to maintaining the factory bias (ie., safe understeer on anything other than warp speed corners). I run 22/29 (with a bigger 22mm rear sway bay set full hard) and would describe it as "neutral". From what I read lately, more people are running bigger and bigger rear torsion bars, such as 22/30 even up to 22/33. If I did it again, I would go at least 22/30 and set the rear sway bar a little softer. At the other, less extreme, end of the scale, shops like Ninemeister refer to a "fast road" upgrade where they leave the 18.8mm bars up front and put Turbo 26mm bars in the rear - this is the Turbo set-up but without the extra weight in the back. The common point being that most people are tending to stiffen the rear a little more than the front to get rid of a little understeer, whereas IMHO your 21/26 and 22/27 examples will increase understeer.
When I was involved in setting up a club race car - a very light 2.4E - we stuck with std torsion bars but used sway bars to stiffen the rear - 22/19mm rear/front. Bigger torsion bars would have been better but we were poor and this proved good enough to win its class 2 years in a row and an overall club championship. For 911s, "loose is fast".
HTH
Richard
bones
New member
Hear what your saying Richard but I believe you track your car and I'm advising for road use with a bit of a bias towards where I do most of my quickish driving, which is B-roads, also my car is lighter and I wouldn't want to advise people to turn their road cars into Karts unless they asked for that. Afetr a lot of research and conversation with your pal Steve Winter (excellent chap at Jaz Porsche), Francis Tuthill and others , the set you are suggestig is probably very good for the track but probably too hard for the rough roads we have now. Perhaps a compromise could be achieved by putting the bars on you suggest whilst revalving the shocks for a softer rebound (Bilstein Sports fitted to all 'Sportpack SCs have these as standard). Personally for a road car I'd stick with what I suggested bearing in mind the standard torsion bar sizes for SCs are
24.1mm r, 18.8mm fr.
Anti-roll bars are 20mm fr, 18r.
I'd consider changes to the anti-roll bars after revalving, changing the torsion bars and re-aligning, by the way I believe these were the figures I quoted which are similar to yours for the softest stiffening upgrade, these are 'ball park figures' for a road car as most SC owners can easily handle the current understeer situation. The final set up should be matched to how the dampers are valved.
21(22)fr & 26(27)r.
24.1mm r, 18.8mm fr.
Anti-roll bars are 20mm fr, 18r.
I'd consider changes to the anti-roll bars after revalving, changing the torsion bars and re-aligning, by the way I believe these were the figures I quoted which are similar to yours for the softest stiffening upgrade, these are 'ball park figures' for a road car as most SC owners can easily handle the current understeer situation. The final set up should be matched to how the dampers are valved.
21(22)fr & 26(27)r.
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I hear what you are saying about keeping road cars soft but you are going to more understeer than OE. I have never heard of a car with 21/26 - ever. You can't just add 2mm or 3mm to the standard bar sizes and expect the balance to stay the same. You will in reality be adding much more stiffness to the front than the rear. The usual fast road uprade is 18.8/26 (ask Ninemeister about their project car) and the next step would be 21/27 or 22/28. If yo want a 100% road car then stop at step one or keep the OE bars and just get a nice set of shocks.
If Steve and Tuthill are saying 21/26 or 22/27, they are wrong (bold call, I know), but I think I understand why they are saying it. The thing about all these stiffer set-ups is that you get the work done and bang on a set of good modern tyres like SO2s and they all feel great on the road where 99.9% of the time you are not at the limits of the car. It is only on a track with long high speed corners that you really feel the balance of the car. In slow corners you can make a car understeer or oversteer depending on how you drive it. So, I guess it doesn't matter all that much for a road car. They are telling you about set-ups that have worked pretty well but are thinking of what is optimum.
What I would suggest is that the conventional wisdom has moved on. The Club Racing scene in the US is much more competitive than here and the cars are much more developed. What I have observed in the last year is a trend towards softer front and harder rear ends. Why? because this provides a *better* balance than OE - backed up by faster lap times. This is the logic I applied to my car but I didn't have the guts to follow thru and stick really big t-bars in the rear. I would never recommend a set-up with more inherent understeer than OE - which is what 21/26 or 22/27 will acheive. Maintain that OE balance if you want to be very conservative, or go a little closer to neutral by stiffening the rear if you want to make the car handle better.
I have recommended on the 3.2 forum an even simpler upgrade which would be my preference for a 100% road car, which would be std t-bars with new shocks and a bigger adjustable 22mm rear sway bar, plus 7/8x16 wheels. This is how I ran my own car for about 3 years before deciding to dive into the track car thing. Probably the best handling 911 for the road that I have ever driven was a 911E with OE 18.8/24mm t-bars, 19/22mm sways and Koni Red shocks - very supple ride, great balance, and just stiff enough in the rear to make it fun.
I get what you are syaing about road cars - my car is borderline stiff for B roads - not so stiff that it skips rather than slides but not as comfortable as standard set-up.
HTH
Richard
If Steve and Tuthill are saying 21/26 or 22/27, they are wrong (bold call, I know), but I think I understand why they are saying it. The thing about all these stiffer set-ups is that you get the work done and bang on a set of good modern tyres like SO2s and they all feel great on the road where 99.9% of the time you are not at the limits of the car. It is only on a track with long high speed corners that you really feel the balance of the car. In slow corners you can make a car understeer or oversteer depending on how you drive it. So, I guess it doesn't matter all that much for a road car. They are telling you about set-ups that have worked pretty well but are thinking of what is optimum.
What I would suggest is that the conventional wisdom has moved on. The Club Racing scene in the US is much more competitive than here and the cars are much more developed. What I have observed in the last year is a trend towards softer front and harder rear ends. Why? because this provides a *better* balance than OE - backed up by faster lap times. This is the logic I applied to my car but I didn't have the guts to follow thru and stick really big t-bars in the rear. I would never recommend a set-up with more inherent understeer than OE - which is what 21/26 or 22/27 will acheive. Maintain that OE balance if you want to be very conservative, or go a little closer to neutral by stiffening the rear if you want to make the car handle better.
I have recommended on the 3.2 forum an even simpler upgrade which would be my preference for a 100% road car, which would be std t-bars with new shocks and a bigger adjustable 22mm rear sway bar, plus 7/8x16 wheels. This is how I ran my own car for about 3 years before deciding to dive into the track car thing. Probably the best handling 911 for the road that I have ever driven was a 911E with OE 18.8/24mm t-bars, 19/22mm sways and Koni Red shocks - very supple ride, great balance, and just stiff enough in the rear to make it fun.
I get what you are syaing about road cars - my car is borderline stiff for B roads - not so stiff that it skips rather than slides but not as comfortable as standard set-up.
HTH
Richard
Hi Bruce,
Yes, that was me - apologies for not remembering your name, I think all the sun and beer had altered my brain a little!
We had a great run back, following a lovely 356: here's a couple of vids:
Big movie (46mb)
Small movie (7mb)
Back onto subject, how much has your SC been lowered by Bruce, because I thought it looked just right at that height.
Lewis.
Yes, that was me - apologies for not remembering your name, I think all the sun and beer had altered my brain a little!
We had a great run back, following a lovely 356: here's a couple of vids:
Big movie (46mb)
Small movie (7mb)
Back onto subject, how much has your SC been lowered by Bruce, because I thought it looked just right at that height.
Lewis.
Hi Lewis
yes Le Mans was really hot this year, it was really horid having to drink more beer more often to keep cool!!
My car is lowered so that the top of the rear tyres are level with the outer wheel arch and the fronts you can just slide a finger between the tyre arch. Not very scientific way to describe it but it ended at this height after a visit to Tuthills last winter.I have some pictures I could post or E mail if required, do you know how to shrink jpeg files so that they will upload to this site, I will down load the lemans videos overnight
regards
Bruce
yes Le Mans was really hot this year, it was really horid having to drink more beer more often to keep cool!!
My car is lowered so that the top of the rear tyres are level with the outer wheel arch and the fronts you can just slide a finger between the tyre arch. Not very scientific way to describe it but it ended at this height after a visit to Tuthills last winter.I have some pictures I could post or E mail if required, do you know how to shrink jpeg files so that they will upload to this site, I will down load the lemans videos overnight
regards
Bruce
Bruce,
Are you going to Lemans again? I think we are going to book up for the same campsite as last year.
I am looking to lower my car a bit more, but I am not sure how far to go. I thought yours looked great and would like to do the same. I was wondering if you could do me a favour and measure the ground clearance at the front and back of the car for me? I think that would be a more reliable measure than the clearance between the top of the tyre and the wing - what do you think?
I'd really appreciate it if you could and i'll sort you out a few beers at lemans in return!!
Cheers,
Lewis.
Are you going to Lemans again? I think we are going to book up for the same campsite as last year.
I am looking to lower my car a bit more, but I am not sure how far to go. I thought yours looked great and would like to do the same. I was wondering if you could do me a favour and measure the ground clearance at the front and back of the car for me? I think that would be a more reliable measure than the clearance between the top of the tyre and the wing - what do you think?
I'd really appreciate it if you could and i'll sort you out a few beers at lemans in return!!
Cheers,
Lewis.
Hi Lewis
I hope all is well with you and the car,
Unfortunatly Le mans for me is off this year as I am working abroad for a year, but as compensation a trip to the ring is being planned for August[]
I am not sure exactly what spec my car is lowered to but I just checked your earlier post and I see that Tuthills did your lowering. Guess what my car has been with them for the last two months and I pick it up tomorrow. I will ask one of the chaps there to tell me exactly what the ride height is set too as they have done quite a few suspension mods this winter, I'll post the results back here.
Here is a picture of the car from lemans last year just before the Porsche curves
http://i33.photobucket.com/albums/d76/bruceb1964/lemans2005005.jpg
Enjoy the cold beers at the sarthe, cheers
I hope all is well with you and the car,
Unfortunatly Le mans for me is off this year as I am working abroad for a year, but as compensation a trip to the ring is being planned for August[
] I am not sure exactly what spec my car is lowered to but I just checked your earlier post and I see that Tuthills did your lowering. Guess what my car has been with them for the last two months and I pick it up tomorrow. I will ask one of the chaps there to tell me exactly what the ride height is set too as they have done quite a few suspension mods this winter, I'll post the results back here.
Here is a picture of the car from lemans last year just before the Porsche curves
http://i33.photobucket.com/albums/d76/bruceb1964/lemans2005005.jpg
Enjoy the cold beers at the sarthe, cheers
Hi Lewis
This lowering thing is not a science but I have been advised as follows
1) set the rear suspension to the desired ride height
2) set the front suspension height such that there is a 1 degree rake when measured on the top of the sill (ie lower.)
My car has the 16" fuchs with rear 225/50 tyres. The top of the rear wheel is set to be level with the outer arch. Tuthills have set the front height using 1 deg rake.
I set my rear ride height some years ago to what I thought looked low but not overly so. Despite various geomety changes and new torsion bars I have never or knowingly had the car lowered further. It seems a good compromise at these settings without any problems with speed bumps
regards
This lowering thing is not a science but I have been advised as follows
1) set the rear suspension to the desired ride height
2) set the front suspension height such that there is a 1 degree rake when measured on the top of the sill (ie lower.)
My car has the 16" fuchs with rear 225/50 tyres. The top of the rear wheel is set to be level with the outer arch. Tuthills have set the front height using 1 deg rake.
I set my rear ride height some years ago to what I thought looked low but not overly so. Despite various geomety changes and new torsion bars I have never or knowingly had the car lowered further. It seems a good compromise at these settings without any problems with speed bumps
regards
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