Increasing Negative Cambers
02-24-2015, 10:39 PM
#31
I just had my track alignment done. I went with -2.3 all the way around. The problem my guys ran into was the thread length on the toe links. I was not willing to push the thread engagement to what I felt was an unsafe number. As far as I know no one makes toe links yet with a longer shaft.
02-25-2015, 12:25 AM
#32
I am at about 5 threads of engagement now and wasn't willing to go further for safety concerns.
02-25-2015, 02:03 AM
#33
As an update, I was advised to stick with the Porsche Motorsport shims, and stay away from the Tarett shims because the material is too soft.
Also, there was an issue with measurement of camber on my car, and turns out they can get about -1.6 F, not -1.4. They still say they can get -2.3 R without shims.
If my track event this weekend isn't cancelled, I may just try -1.6 F and R for now, if I can't get shims in time, then adjust after this event based on the tire wear (assuming the tires make it through the event!).
Also, there was an issue with measurement of camber on my car, and turns out they can get about -1.6 F, not -1.4. They still say they can get -2.3 R without shims.
If my track event this weekend isn't cancelled, I may just try -1.6 F and R for now, if I can't get shims in time, then adjust after this event based on the tire wear (assuming the tires make it through the event!).
02-27-2015, 08:36 AM
#34
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doba, thanks for guidance on rear toe adjustment points. I found the eccentric for rear toe very high within rear suspension.. Didn't yet adjust but it appears it is actually the inboard mounting point for the motor which controls the rear adjustable toe-will be difficult to get to with wheels on the car which is the normal situation when doing the alignment. Ugh.
02-27-2015, 09:20 AM
#35
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I don't know what the material is. The advice came from a shop whose owner is a pro racer, racing mainly 911 cup cars. The owner also has a 991 GT3.
Also, FWIW, I put a Tarett front sway bar and drop links in my 997. Soon after, one of the bolts connecting the drop link to the sway bar broke while I was on track, causing snap oversteer. Fortunately, it wasn't a high speed turn and I was able to catch it, but if it happened two turns prior I could have been in big trouble. We wound up replacing all of the bolts with higher-grade bolts. So I've generally lost some confidence in the quality of Tarett products, and am not likely to buy from them again.
Also, FWIW, I put a Tarett front sway bar and drop links in my 997. Soon after, one of the bolts connecting the drop link to the sway bar broke while I was on track, causing snap oversteer. Fortunately, it wasn't a high speed turn and I was able to catch it, but if it happened two turns prior I could have been in big trouble. We wound up replacing all of the bolts with higher-grade bolts. So I've generally lost some confidence in the quality of Tarett products, and am not likely to buy from them again.
02-27-2015, 09:43 AM
#36
100 lbs = .1 dgree
Based on what you said I'd say you weigh about 170 lbs
02-27-2015, 10:05 AM
#37
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Thanks Mike. I was going to step in and clear that point up.
It will vary on individual cars and alignment equipment. With my car we achieved a maximum of -2.15' at the front using the factory gear without upsetting castor. Rear max out was -1.55'. I dont believe he top mounts are rotatable and if so would alter castor? castor is really important on the 991 GT3 as there isnt alot of room under there to push the wheel forward or back without fouling the guard liner on hard lock.
I was told using Porsche Motorsport shims on the LCAs was the way to do this properly so I bought the shims. They are no cheap for what they are.
I understand that 10mm shims total = -1.0 camber approx.
My car sees far more road miles than track miles (assumes average of 7-8 full track days a year). I do not think I need to go out to -2.7 front and -2.5 rear like the more dedicated track guys here as the MPSC2 are very expensive in NZ (3200 usd a set) and tyre wear becomes the issue for the sake of maybe less than 0.5s on our short tracks here....
It will vary on individual cars and alignment equipment. With my car we achieved a maximum of -2.15' at the front using the factory gear without upsetting castor. Rear max out was -1.55'. I dont believe he top mounts are rotatable and if so would alter castor? castor is really important on the 991 GT3 as there isnt alot of room under there to push the wheel forward or back without fouling the guard liner on hard lock.
I was told using Porsche Motorsport shims on the LCAs was the way to do this properly so I bought the shims. They are no cheap for what they are.
I understand that 10mm shims total = -1.0 camber approx.
My car sees far more road miles than track miles (assumes average of 7-8 full track days a year). I do not think I need to go out to -2.7 front and -2.5 rear like the more dedicated track guys here as the MPSC2 are very expensive in NZ (3200 usd a set) and tyre wear becomes the issue for the sake of maybe less than 0.5s on our short tracks here....
I'm going to drive my car on the road most of the time but am signed up to drive it in appox. 5-7 track event's this season. Would you share with me your thoughts on what I should set my camber on my fronts and rears?
Thank you,
Jerry
02-27-2015, 10:40 AM
#38
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You are probably in the same camp as me. I will drive the car around 6000 miles in a year. Half of those will be "touring" around 1000 will be track (lets say 8 days a year) and 2000 will be fast back rooad sunday morning "canyon runs".
I chose just t use teh factory alignment (although I have bought the shims should I wish to make the car more track oriented in the future). I have gone for -2.15 F and -1.55 R (my geo spec sheet is on another thread on this forum with a few other members who also posted theirs). My overall tyre wear with these settings is pretty good - the outside wears more on the track days but he inside wears more on the road. Having now completed 6000 miles including 3.5 track days the insides are around 1-2mm more worn than the outsides but UI have 2 full track days coming up after another 1000 touring miles and then the tyres will finally be deal (7500 miles not bad!). I expect when they die wear will be pretty even (although our track wears one side faster than the other due to its turns - but thats a seperate matter).
My advise would be to start with similar settings to me. I have kept toe and castor all the same as factory as is recommended. Sure you will sacrifice a few tenth on the track but it will take you a while in this car to get good enough to notice and the upside is youll get plenty more miles from the tyres on the street....all IMO of course :-)
02-27-2015, 11:02 AM
#39
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FWIW, since I changed my cambers from -1.5 to -2.0, the car feels a bit different on the road. The effect, if any, is subtle, and I could very well be imagining it (!), so take with a grain of salt, but the car seems to feel slightly more aggressive: sharper steering response and slightly firmer ride. Grip seems to also be a hair lower, maybe because -2.0 is a bit too much camber on the road, since the car isn't being leaned on nearly as hard as on the track, and the car doesn't roll much anyway. So I'd suggest not taking the cambers past about -2.0 for a car mainly driven on the road. Even the factory -1.5 may be fine for a car tracked a few times a year but mainly driven on the road.
02-27-2015, 11:36 AM
#40
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Hi Jerry.
You are probably in the same camp as me. I will drive the car around 6000 miles in a year. Half of those will be "touring" around 1000 will be track (lets say 8 days a year) and 2000 will be fast back rooad sunday morning "canyon runs".
I chose just t use teh factory alignment (although I have bought the shims should I wish to make the car more track oriented in the future). I have gone for -2.15 F and -1.55 R (my geo spec sheet is on another thread on this forum with a few other members who also posted theirs). My overall tyre wear with these settings is pretty good - the outside wears more on the track days but he inside wears more on the road. Having now completed 6000 miles including 3.5 track days the insides are around 1-2mm more worn than the outsides but UI have 2 full track days coming up after another 1000 touring miles and then the tyres will finally be deal (7500 miles not bad!). I expect when they die wear will be pretty even (although our track wears one side faster than the other due to its turns - but thats a seperate matter).
My advise would be to start with similar settings to me. I have kept toe and castor all the same as factory as is recommended. Sure you will sacrifice a few tenth on the track but it will take you a while in this car to get good enough to notice and the upside is youll get plenty more miles from the tyres on the street....all IMO of course :-)
You are probably in the same camp as me. I will drive the car around 6000 miles in a year. Half of those will be "touring" around 1000 will be track (lets say 8 days a year) and 2000 will be fast back rooad sunday morning "canyon runs".
I chose just t use teh factory alignment (although I have bought the shims should I wish to make the car more track oriented in the future). I have gone for -2.15 F and -1.55 R (my geo spec sheet is on another thread on this forum with a few other members who also posted theirs). My overall tyre wear with these settings is pretty good - the outside wears more on the track days but he inside wears more on the road. Having now completed 6000 miles including 3.5 track days the insides are around 1-2mm more worn than the outsides but UI have 2 full track days coming up after another 1000 touring miles and then the tyres will finally be deal (7500 miles not bad!). I expect when they die wear will be pretty even (although our track wears one side faster than the other due to its turns - but thats a seperate matter).
My advise would be to start with similar settings to me. I have kept toe and castor all the same as factory as is recommended. Sure you will sacrifice a few tenth on the track but it will take you a while in this car to get good enough to notice and the upside is youll get plenty more miles from the tyres on the street....all IMO of course :-)
Heading to my first DE on April 7-8th at VIR can't wait. I'm so sick of all the snow we have been having here in Massachusetts!!
Come on Spring!!
Jerry
02-27-2015, 06:36 PM
#41
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Hi Jerry.
You are probably in the same camp as me. I will drive the car around 6000 miles in a year. Half of those will be "touring" around 1000 will be track (lets say 8 days a year) and 2000 will be fast back rooad sunday morning "canyon runs".
I chose just t use teh factory alignment (although I have bought the shims should I wish to make the car more track oriented in the future). I have gone for -2.15 F and -1.55 R (my geo spec sheet is on another thread on this forum with a few other members who also posted theirs). My overall tyre wear with these settings is pretty good - the outside wears more on the track days but he inside wears more on the road. Having now completed 6000 miles including 3.5 track days the insides are around 1-2mm more worn than the outsides but UI have 2 full track days coming up after another 1000 touring miles and then the tyres will finally be deal (7500 miles not bad!). I expect when they die wear will be pretty even (although our track wears one side faster than the other due to its turns - but thats a seperate matter).
My advise would be to start with similar settings to me. I have kept toe and castor all the same as factory as is recommended. Sure you will sacrifice a few tenth on the track but it will take you a while in this car to get good enough to notice and the upside is youll get plenty more miles from the tyres on the street....all IMO of course :-)
You are probably in the same camp as me. I will drive the car around 6000 miles in a year. Half of those will be "touring" around 1000 will be track (lets say 8 days a year) and 2000 will be fast back rooad sunday morning "canyon runs".
I chose just t use teh factory alignment (although I have bought the shims should I wish to make the car more track oriented in the future). I have gone for -2.15 F and -1.55 R (my geo spec sheet is on another thread on this forum with a few other members who also posted theirs). My overall tyre wear with these settings is pretty good - the outside wears more on the track days but he inside wears more on the road. Having now completed 6000 miles including 3.5 track days the insides are around 1-2mm more worn than the outsides but UI have 2 full track days coming up after another 1000 touring miles and then the tyres will finally be deal (7500 miles not bad!). I expect when they die wear will be pretty even (although our track wears one side faster than the other due to its turns - but thats a seperate matter).
My advise would be to start with similar settings to me. I have kept toe and castor all the same as factory as is recommended. Sure you will sacrifice a few tenth on the track but it will take you a while in this car to get good enough to notice and the upside is youll get plenty more miles from the tyres on the street....all IMO of course :-)
FWIW, since I changed my cambers from -1.5 to -2.0, the car feels a bit different on the road. The effect, if any, is subtle, and I could very well be imagining it (!), so take with a grain of salt, but the car seems to feel slightly more aggressive: sharper steering response and slightly firmer ride. Grip seems to also be a hair lower, maybe because -2.0 is a bit too much camber on the road, since the car isn't being leaned on nearly as hard as on the track, and the car doesn't roll much anyway. So I'd suggest not taking the cambers past about -2.0 for a car mainly driven on the road. Even the factory -1.5 may be fine for a car tracked a few times a year but mainly driven on the road.
One downside of added negative camber for the street for me has been that the car is more prone to over-sensitivity to road conditions; for example, greater tramlining on freeway grooves. I don't know whether it's the active filtering in the EM steering of the GT3, but even that hasn't been noticeable where it definitely was with my earlier 911's with similar camber settings.
Last edited by Mike in CA; 02-27-2015 at 07:32 PM.
10-12-2017, 04:50 PM
#42
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I am just beginning to explore the world of increased camber on 991 GT3. But I wanted to share some info. I have a 2014 GT3 and I asked my dealer service mgr to give me the maximum negative camber he could get. That turned out to be -2.36 in front. Based on some very old personal experience with an early 70s 911 GTU, on which I did my own alignment, I asked him to add .15 degrees to that and set the rear to -2.52. I don’t know if there’s more to be had on the rear. I will find out since I just read that there might be a problem with shims in the rear because of the RWS. The car is only used at the track except when I have to drive it to the dealer or to get gas. I have a friend who just bought a 2016 and matched my camber. He says he knows another guy who uses pretty much the same camber. So I don’t understand the comments about a maximum, of -1.5 front or rear. I have had a lot of 911s and find it hard to believe that kind of manufacturing variation. Unless it was a running manufacturing change. Based on the wear patterns front and rear, I probably need at least another degree. Any comments or advise would be appreciated.
10-14-2017, 10:51 AM
#43
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I am just beginning to explore the world of increased camber on 991 GT3. But I wanted to share some info. I have a 2014 GT3 and I asked my dealer service mgr to give me the maximum negative camber he could get. That turned out to be -2.36 in front. Based on some very old personal experience with an early 70s 911 GTU, on which I did my own alignment, I asked him to add .15 degrees to that and set the rear to -2.52. I don’t know if there’s more to be had on the rear. I will find out since I just read that there might be a problem with shims in the rear because of the RWS. The car is only used at the track except when I have to drive it to the dealer or to get gas. I have a friend who just bought a 2016 and matched my camber. He says he knows another guy who uses pretty much the same camber. So I don’t understand the comments about a maximum, of -1.5 front or rear. I have had a lot of 911s and find it hard to believe that kind of manufacturing variation. Unless it was a running manufacturing change. Based on the wear patterns front and rear, I probably need at least another degree. Any comments or advise would be appreciated.
10-15-2017, 12:26 AM
#44
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Thanks for your reply. I let my mechanic talk me into changing my camber to factory spec which was -1.5. I very quickly chewed up 2 sets of tires with poor handling compared to the original -2.0 that was on the car when I bought it. I then had it restored to the original, -2.0. Tire wear was less and handling improved, but as expected, tire wear was on the outer 1/3 of the tires, front and rear. I then had camber changed to the numbers I mentioned: 2.36f and 2.52r. Handling improved further and wear was more distributed but still on the outside one half. Remember that 90% or more of miles are track only. Does your comment mean that there is some disadvantage to increased camber, other than street driving wear on the inside corner? And yes I am presently using MPSC2, or occasionally Tropheo R. I have many thousands of track miles mostly in racing in the 70s and 80s, but I am getting back into things after a hiatus of about 25 yrs. so your advice is greatly appreciated by an old man!
Dave
Dave
10-15-2017, 09:03 PM
#45
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Thanks for your reply. I let my mechanic talk me into changing my camber to factory spec which was -1.5. I very quickly chewed up 2 sets of tires with poor handling compared to the original -2.0 that was on the car when I bought it. I then had it restored to the original, -2.0. Tire wear was less and handling improved, but as expected, tire wear was on the outer 1/3 of the tires, front and rear. I then had camber changed to the numbers I mentioned: 2.36f and 2.52r. Handling improved further and wear was more distributed but still on the outside one half. Remember that 90% or more of miles are track only. Does your comment mean that there is some disadvantage to increased camber, other than street driving wear on the inside corner? And yes I am presently using MPSC2, or occasionally Tropheo R. I have many thousands of track miles mostly in racing in the 70s and 80s, but I am getting back into things after a hiatus of about 25 yrs. so your advice is greatly appreciated by an old man!
Dave
Dave
Lots of people have tried increasing camber and otherwise messing with alignment, with no real improvement in grip, lap time, or tire wear, and sometimes have made those things worse. The exception is that I've heard of couple cases where people have greatly increased camber (over 3 degrees) and otherwise changed the alignment, with apparently some increase in pace, but then the car is significantly worse on the road.