Parr or JZM - Guidance Sought Please
Discussion
housemaster said:
jeremyc said:
I have a Parr 'fast road' geometry setup on my Mk1 and can thoroughly recommend both them and the improvements to handling. 
Jeremy, where are the changes most obvious. Turn in, dialling out understeer, reducing tram lining, better handling over the bumps??
The car is a little lower, so that may be a consideration if you have regular clearance problems. Oh, and my rear tyre wear has been perfectly even across the whole width - having changed them earlier this week I was admiring the great impression of perfectly smooth slicks the old tyres were doing.
I guess I am not expecting to remove the tramlining or fidgeting over the bumps, that as they say is the nature of the beast and I love it more for it, but I do want to remove that vague feeling at initial turn in and dial out as much of that initial understeer as possible. I will provide a full update report after the work is done!
Edited by housemaster on Friday 8th December 17:28
housemaster said:
I guess I am not expecting to remove the tramlining or fidgeting over the bumps, that as they say is the nature of the beast and I love it more for it, but I do want to remove that vague feeling at initial turn in and dial out as much of that initial understeer as possible. I will provide a full update report after the work is done!
Edited by housemaster on Friday 8th December 17:28
HM, In comparison with the MK1 the MK2 is rock steady when it comes to tramlining and fidgiting over bumps !
What is really noticeable on the MK1 as previously mentioned, is how sharp the initial bite is on turn in when compared to the MK2 I drove.
Steve R , can this be dialled out to the degree that the MK2 can be made to feel like the older car ?
I thought Porsche had possibly realised this was an "issue" on the later car and had addressed it by modifying the hubs/uprights on the GT3 RS ?
HM, when are you booked in at JZM ?
slippydiff said:
housemaster said:
I guess I am not expecting to remove the tramlining or fidgeting over the bumps, that as they say is the nature of the beast and I love it more for it, but I do want to remove that vague feeling at initial turn in and dial out as much of that initial understeer as possible. I will provide a full update report after the work is done!
Edited by housemaster on Friday 8th December 17:28
HM, In comparison with the MK1 the MK2 is rock steady when it comes to tramlining and fidgiting over bumps !
What is really noticeable on the MK1 as previously mentioned, is how sharp the initial bite is on turn in when compared to the MK2 I drove.
Steve R , can this be dialled out to the degree that the MK2 can be made to feel like the older car ?
I thought Porsche had possibly realised this was an "issue" on the later car and had addressed it by modifying the hubs/uprights on the GT3 RS ?
HM, when are you booked in at JZM ?
Monday 18th, I plan to spend the day there and observe, pop down for a coffee if your about!
Steve
Edited by housemaster on Friday 8th December 18:10
steve rance said:
They are both good. Parr ultimately has more motorsport knowledge than JZM (Parr are Porsche UK's works motorsport team so they should do) and will set up a car specifically to suit your requirements if you ask them, rather than giving you an either or tyre of choice.
Steve, Jonas and the guys at JZM have over 60+ years experience in Porsches and motorsport racing so I suspect they do know a thing or two about motorsport - even if Parr are the current Carrera Cup tech support.
I have never known JZM to give an "either or" choice as you suggest. Over the past year, for example, they started me out on a fairly gradual fast road setup, and I've probably had about 3-4 geos since then each time making the setup slightly more aggressive to complement my improving driving skills over the same time frame. This has allowed the car to be optimised for my driving ability at any point in time in a progressive manner. I know for a fact that JZM work directly with Manthey to share their knowledge and also glean knowledge from the most successful German Porsche racing team... and I think Manthey have *slightly* more knowledge than Parr.
It's not a surprise that JZM are the official Manthey outfit in the UK. In fact, the fact that Parr have lots of experience with the current Carrera Cup cars is probably why some of their "fast road" setups have been reported to not work quite as well as the Manthey/JZM setups on the road. Parr setups may work well on various tracks, but I'm not 100% convinced that Parr has as much on-road experience of getting GT3s to work on road. You are certainly a good driver, but I actually wonder if your skill has been honed around a setup where your own driving skills have adapted to work around the compromises of your setup. ie, would you be even quicker if you drove for a JZM/Manthey team?
I don't want to knock Parr, but in defence of JZM I do think your comments are a tad unfair - especially considering you advertise Parr corporate plates at all trackdays. I should add that I am a very happy customer of JZM and have been astounded by their ability to set up my car based on my feedback to help me improve to be a better driver. The car is a tool/aid, not a benchmark for me to attain.
Cheers
Edited by polarexpress on Saturday 9th December 01:12
slippydiff said:
housemaster said:
I guess I am not expecting to remove the tramlining or fidgeting over the bumps, that as they say is the nature of the beast and I love it more for it, but I do want to remove that vague feeling at initial turn in and dial out as much of that initial understeer as possible. I will provide a full update report after the work is done!
Edited by housemaster on Friday 8th December 17:28
HM, In comparison with the MK1 the MK2 is rock steady when it comes to tramlining and fidgiting over bumps !
What is really noticeable on the MK1 as previously mentioned, is how sharp the initial bite is on turn in when compared to the MK2 I drove.
Steve R , can this be dialled out to the degree that the MK2 can be made to feel like the older car ?
I thought Porsche had possibly realised this was an "issue" on the later car and had addressed it by modifying the hubs/uprights on the GT3 RS ?
HM, when are you booked in at JZM ?
Not driven a mark 1, but if you want to make the front of a mk2/RS pointy and evil just dial in some toe out at the front. Mine had this on and was a nightmare - either it got knocked out or whoever geo'd it got the toe the wrong way. Made the car a camber seeking missile.
Anyway this stuff is an iterative process whoever you go with, so don't expect to get the perfect setup for whatever you want first time as its unlikely to happen and your requirements will probably change over time too.
DanH said:
Not driven a mark 1, but if you want to make the front of a mk2/RS pointy and evil just dial in some toe out at the front. Mine had this on and was a nightmare - either it got knocked out or whoever geo'd it got the toe the wrong way. Made the car a camber seeking missile.
Anyway this stuff is an iterative process whoever you go with, so don't expect to get the perfect setup for whatever you want first time as its unlikely to happen and your requirements will probably change over time too.
Dan, Anyway this stuff is an iterative process whoever you go with, so don't expect to get the perfect setup for whatever you want first time as its unlikely to happen and your requirements will probably change over time too.
I think that you are talking about opposite effects.
With too much static front toe-out, yes, the car will follow grooves in the road. Think of the tyre going over a surface that is suddenly uneven lengthwise, in which case the tyre wants, as always, to take the path of least resistance. As the toe is pointing outwards, the tyres rolls in the direction of the toe - into the groove.
However, that will tend to make the car understeer when you have lock on. I would call this the opposite to "pointy", although perhaps you meant the word differently.
With front toe-out, in a bend as weight builds on the laden outside tyre, the fact that it is pointing out tends to draw the car in that direction, much as it does when following a groove.
Increasing front toe-out (within limits) would tend to diminish a car's turn-in, although it would be safer than toe-in.
This stuff starts to matter with bump steer. Some guys like bump toe-in, because it is more stable under braking, especially split-surface braking.
Other guys will tell you that it is too easy for a car with bump toe-in to snap into oversteer when you have some lock on.
DanH said:
slippydiff said:
housemaster said:
I guess I am not expecting to remove the tramlining or fidgeting over the bumps, that as they say is the nature of the beast and I love it more for it, but I do want to remove that vague feeling at initial turn in and dial out as much of that initial understeer as possible. I will provide a full update report after the work is done!
Edited by housemaster on Friday 8th December 17:28
HM, In comparison with the MK1 the MK2 is rock steady when it comes to tramlining and fidgiting over bumps !
What is really noticeable on the MK1 as previously mentioned, is how sharp the initial bite is on turn in when compared to the MK2 I drove.
Steve R , can this be dialled out to the degree that the MK2 can be made to feel like the older car ?
I thought Porsche had possibly realised this was an "issue" on the later car and had addressed it by modifying the hubs/uprights on the GT3 RS ?
HM, when are you booked in at JZM ?
Not driven a mark 1, but if you want to make the front of a mk2/RS pointy and evil just dial in some toe out at the front. Mine had this on and was a nightmare - either it got knocked out or whoever geo'd it got the toe the wrong way. Made the car a camber seeking missile.
Anyway this stuff is an iterative process whoever you go with, so don't expect to get the perfect setup for whatever you want first time as its unlikely to happen and your requirements will probably change over time too.
Sorry Dan,
Perhaps I'm guilty of using the wrong word here , but by "pointy" I meant a crisp measured turn in. Not darty as I suspect you thought I meant.
The MK1 doesn't seem to suffer the large amount of initial turn in understeer that the MK2 car has. (I haven't driven an RS so I'm in no position to make any constructive observations on them)
I did however read on Rennlist IIRC that the RS front uprights were engineered by Porsche to remove the large amount of understeer present in the "standard" MK2 car.
My car, as set up by JZM has a small amount of what I call stabilizing understeer (which prevents the darty feel it had prior to JZM adjusting it). After you've driven through that initial phase and loaded up the front tyres you are left with a clear concise turn in/ and front end grip.
The same stabilizing understeer was present on the MK2 GT3 I drove, but to a greater degree, thus the initial understeer required a far larger application of steering lock to find consistent front end grip during that initial turn in phase.
At lower speeds that's not a problem, but at higher speeds I found it required a "leap of faith" that felt unnatural and totally at odds with the usual 911 chassis balance.
I know most of us on here don't normally give a monkeys for what the journos say in the specialist Porsche press, they have however made comments about the steering of the MK2 GT3 lacking the precision of the earlier car, and from my experience that seems a a fair and accurate summation.
Edited by slippydiff on Saturday 9th December 01:19
Edited by slippydiff on Saturday 9th December 01:20
flemke said:
DanH said:
Not driven a mark 1, but if you want to make the front of a mk2/RS pointy and evil just dial in some toe out at the front. Mine had this on and was a nightmare - either it got knocked out or whoever geo'd it got the toe the wrong way. Made the car a camber seeking missile.
Anyway this stuff is an iterative process whoever you go with, so don't expect to get the perfect setup for whatever you want first time as its unlikely to happen and your requirements will probably change over time too.
Dan, Anyway this stuff is an iterative process whoever you go with, so don't expect to get the perfect setup for whatever you want first time as its unlikely to happen and your requirements will probably change over time too.
I think that you are talking about opposite effects.
With too much static front toe-out, yes, the car will follow grooves in the road. Think of the tyre going over a surface that is suddenly uneven lengthwise, in which case the tyre wants, as always, to take the path of least resistance. As the toe is pointing outwards, the tyres rolls in the direction of the toe - into the groove.
However, that will tend to make the car understeer when you have lock on. I would call this the opposite to "pointy", although perhaps you meant the word differently.
With front toe-out, in a bend as weight builds on the laden outside tyre, the fact that it is pointing out tends to draw the car in that direction, much as it does when following a groove.
Increasing front toe-out (within limits) would tend to diminish a car's turn-in, although it would be safer than toe-in.
This stuff starts to matter with bump steer. Some guys like bump toe-in, because it is more stable under braking, especially split-surface braking.
Other guys will tell you that it is too easy for a car with bump toe-in to snap into oversteer when you have some lock on.
That'll teach me to talk about geometry
Anyway the car was vile before, but much nicer now that they've dialed in some toe-in. It used to want to throw me into oncoming traffic or a ditch when I hit a bump, and I ended up convinced that they were all like that, little did I know... (I pretty much expected the understeer given it is a 911) In a freak co-incidence, my front toe out was precisely the inverse of what it should have been. I wonder how bad a hangover the person had when doing my geo the first time round
Edited by DanH on Saturday 9th December 01:32
slippydiff said:
DanH said:
slippydiff said:
housemaster said:
I guess I am not expecting to remove the tramlining or fidgeting over the bumps, that as they say is the nature of the beast and I love it more for it, but I do want to remove that vague feeling at initial turn in and dial out as much of that initial understeer as possible. I will provide a full update report after the work is done!
Edited by housemaster on Friday 8th December 17:28
HM, In comparison with the MK1 the MK2 is rock steady when it comes to tramlining and fidgiting over bumps !
What is really noticeable on the MK1 as previously mentioned, is how sharp the initial bite is on turn in when compared to the MK2 I drove.
Steve R , can this be dialled out to the degree that the MK2 can be made to feel like the older car ?
I thought Porsche had possibly realised this was an "issue" on the later car and had addressed it by modifying the hubs/uprights on the GT3 RS ?
HM, when are you booked in at JZM ?
Not driven a mark 1, but if you want to make the front of a mk2/RS pointy and evil just dial in some toe out at the front. Mine had this on and was a nightmare - either it got knocked out or whoever geo'd it got the toe the wrong way. Made the car a camber seeking missile.
Anyway this stuff is an iterative process whoever you go with, so don't expect to get the perfect setup for whatever you want first time as its unlikely to happen and your requirements will probably change over time too.
Sorry Dan,
Perhaps I'm guilty of using the wrong word here , but by "pointy" I meant a crisp measured turn in. Not darty as I suspect you thought I meant.
The MK1 doesn't seem to suffer the large amount of initial turn in understeer that the MK2 car has. (I haven't driven an RS so I'm in no position to make any constructive observations on them)
I did however read on Rennlist IIRC that the RS front uprights were engineered by Porsche to remove the large amount of understeer present in the "standard" MK2 car.
My car, as set up by JZM has a small amount of what I call stabilizing understeer (which prevents the darty feel it had prior to JZM adjusting it). After you've driven through that initial phase and loaded up the front tyres you are left with a clear concise turn in/ and front end grip.
The same stabilizing understeer was present on the MK2 GT3 I drove, but to a greater degree, thus the initial understeer required a far larger application of steering lock to find consistent front end grip during that initial turn in phase.
At lower speeds that's not a problem, but at higher speeds I found it required a "leap of faith" that felt unnatural and totally at odds with the usual 911 chassis balance.
I know most of us on here don't normally give a monkeys for what the journos say in the specialist Porsche press, they have however made comments about the steering of the MK2 GT3 lacking the precision of the earlier car, and from my experience that seems a a fair and accurate summation.
Edited by slippydiff on Saturday 9th December 01:19
Edited by slippydiff on Saturday 9th December 01:20
I'm not knowledgeable enough to draw any conclusions, although I believe the mods to the uprights on the RS served two purposes. Firstly to maintain better suspension geometry when the car is setup at extremely low ride heights - this minimises bump steer although there is some debate as to how low the car needs to be to benefit. Additionally they did work to allow massive amounts of camber which again is probably only really applicable on race cars. The parts are also meant to be hollow and cast from mag which is obviously lighter and more exciting when boring your friends at the pub
I have always run the 911 and rally car with 0 toe for three reasons,
reduces rotational effects caused by wheel locking and hitting puddles,
aids transition from understeer to oversteer, easier to balance and quicker to react.
Its possible to drive it on the road in a straight line.
I know some rally drivers run quite a bit of toe out to optimise point two.
reduces rotational effects caused by wheel locking and hitting puddles,
aids transition from understeer to oversteer, easier to balance and quicker to react.
Its possible to drive it on the road in a straight line.
I know some rally drivers run quite a bit of toe out to optimise point two.
polarexpress said:
steve rance said:
They are both good. Parr ultimately has more motorsport knowledge than JZM (Parr are Porsche UK's works motorsport team so they should do) and will set up a car specifically to suit your requirements if you ask them, rather than giving you an either or tyre of choice.
Steve, Jonas and the guys at JZM have over 60+ years experience in Porsches and motorsport racing so I suspect they do know a thing or two about motorsport - even if Parr are the current Carrera Cup tech support.
I have never known JZM to give an "either or" choice as you suggest. Over the past year, for example, they started me out on a fairly gradual fast road setup, and I've probably had about 3-4 geos since then each time making the setup slightly more aggressive to complement my improving driving skills over the same time frame. This has allowed the car to be optimised for my driving ability at any point in time in a progressive manner. I know for a fact that JZM work directly with Manthey to share their knowledge and also glean knowledge from the most successful German Porsche racing team... and I think Manthey have *slightly* more knowledge than Parr.
It's not a surprise that JZM are the official Manthey outfit in the UK. In fact, the fact that Parr have lots of experience with the current Carrera Cup cars is probably why some of their "fast road" setups have been reported to not work quite as well as the Manthey/JZM setups on the road. Parr setups may work well on various tracks, but I'm not 100% convinced that Parr has as much on-road experience of getting GT3s to work on road. You are certainly a good driver, but I actually wonder if your skill has been honed around a setup where your own driving skills have adapted to work around the compromises of your setup. ie, would you be even quicker if you drove for a JZM/Manthey team?
I don't want to knock Parr, but in defence of JZM I do think your comments are a tad unfair - especially considering you advertise Parr corporate plates at all trackdays. I should add that I am a very happy customer of JZM and have been astounded by their ability to set up my car based on my feedback to help me improve to be a better driver. The car is a tool/aid, not a benchmark for me to attain.
Cheers
Edited by polarexpress on Saturday 9th December 01:12
I have a great deal of respect for Steve and the JZM team. In my opinion, Parr and JZM are the best Porsche tuners in the country. If you took offense at my comments, I am sorry. They were honest, pragmatic and based around my personal experiences of diving many different GT3's set up by Parr, JZM and others. Certainly, the more extreme track set ups that Parr offer are based around my prefences. I have not compromised my driving style to accomodate them. There will always be customers who are not entirely happy with the set up that they have been given by a tuner, but it is very rare that I hear a complaint about the work of either Parr or JZM. That in itself says it all.
Steve R
steve rance said:
I have a great deal of respect for Steve and the JZM team. In my opinion, Parr and JZM are the best Porsche tuners in the country. If you took offense at my comments, I am sorry. They were honest, pragmatic and based around my personal experiences of diving many different GT3's set up by Parr, JZM and others. Certainly, the more extreme track set ups that Parr offer are based around my prefences. I have not compromised my driving style to accomodate them. There will always be customers who are not entirely happy with the set up that they have been given by a tuner, but it is very rare that I hear a complaint about the work of either Parr or JZM. That in itself says it all.
Steve R
Oh, no offence taken Steve. I just thought I'd offer my experience, contrary to yours, that JZM do offer a custom approach towards tuning - not just either/or options. Their experience also extends to motorsport - I am sure JZM are equally capable of offering extreme setups, but it's probably that few of their customers request it with most preferring a car that is still driveable on the road. I guess it's down to the most effective setup for the given driver and car... whether extreme or not is somewhat irrelevant.
Housemaster
Didn't intend to criticise your pedalling abilities, seen too many posts about people with deep pockets looking to go faster when the weakest link is the driver. My MK1 has the Parr Stage 1 setup and I like it. Have done 5+ trackdays this year and the lack of understeer suits me. Will have to improve my pedalling abilities before I debate the finer points of suspension adjustment.
regards
Michael
Didn't intend to criticise your pedalling abilities, seen too many posts about people with deep pockets looking to go faster when the weakest link is the driver. My MK1 has the Parr Stage 1 setup and I like it. Have done 5+ trackdays this year and the lack of understeer suits me. Will have to improve my pedalling abilities before I debate the finer points of suspension adjustment.
regards
Michael
batman69 said:
Housemaster
Didn't intend to criticise your pedalling abilities, seen too many posts about people with deep pockets looking to go faster when the weakest link is the driver. My MK1 has the Parr Stage 1 setup and I like it. Have done 5+ trackdays this year and the lack of understeer suits me. Will have to improve my pedalling abilities before I debate the finer points of suspension adjustment.
regards
Michael
Didn't intend to criticise your pedalling abilities, seen too many posts about people with deep pockets looking to go faster when the weakest link is the driver. My MK1 has the Parr Stage 1 setup and I like it. Have done 5+ trackdays this year and the lack of understeer suits me. Will have to improve my pedalling abilities before I debate the finer points of suspension adjustment.
regards
Michael
No worries Michael, I do have very deep pockets, but the problem is there is just fluff at the bottom of them!
My ambition has always been to refine my car in small and simple stages to eradicate some of the less appealing traits. I bought the GT3 for its purity and driver satisfaction with the aim of doing lots of 'hoons' and some track work. My ego is pretty much in check so I am not looking to be the quickest out there, though I know the basics of making a car go quickly and have done quite a bit of track work in the distant past.
I plan to start small and understand how that impacts my car and then progress from there. At the end of the day I am not looking to pull sub 8 minute laps of the Ring in my car for the simple reason I can't afford to. The GT3 is mainly a road car with some track work planned, and I don't see that changing anytime soon, so my focus is making it the best possible road car I can with an eye to some track work. It will always be a comprimise though one I am very happy with!
housemaster said:
Forgive my ignorance, but explain rolling the rims?
On a std car, if you feel under the wheel arches, you will feel a return lip of the outer wing point out perpendicular to the wing, i.e. run parallel with the top of the tyre. This may only be 5-7mm for example.
When the arches are 'rolled', this return edge is rolled back to be flush with the outer wing, i.e. folded back on itself up inside the wing. This allows a lower ride height to be achevied, as the tyres are less likely to touch the return edge of the wing. If you run your finger round the inner wing wheel arch of a 964RS you will see there is no protruding return edge. It takes nothing away from the car at all, and I suspect would be missed in 99% of all 'inspections' done on cars being bought/sold. It only sugests that the car has probably been run with lower than std ride height. On some occasions there are tiny signs where the rolling has taken place, but often this isn't really visible until you're up really close.
A full description of Ackermann angles and bumpsteer (set after you've decided upon the correct Ackermann effect you want to run) can be found in Allan Staniforth's 'Competition Car Suspension' book. Well worth a read.
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