944 Front Springs
06-07-2005, 05:04 PM
#1
Three Wheelin'
Thread Starter
944 Front Springs
This thread is aimed mostly at Geo, but I thought I would post it to everyone, in case someone else has a good idea on the subject.
Geo told me a month or so ago that he was putting 600 lb springs on the front of his ITS 944. The stated reason was that the heavier springs kept movement of the suspension to a minimum and minimize the chance of breaking the already weak 944 ball joint. Geo, if I got any of this wrong, please let me know, as I am stating this from memory. (My memory is kinda short sometimes)
Anyway, I was talking to Jim Pasha last week, and he said that you should only use a max of 350 lb springs on a 944 for ITS racing, and I would assume this would apply to Class I PCA cars. As some of you know, Jim writes for Excellence, and knows the 944 well, and helped engineer a winning ITS 944 in Calif, some years ago. He said the reason for the ball joint failure is the extreme angle of the a arm when you lower the 944. He states that there is no reason to lower the 944 1 1/2 to 2 inches, as many of us do. He said it is better to have lighter springs and heavier sway bars, and only slightly lower the cars.
So, Geo, I was wondering what you thought of that advice. Please, don't anyone think I am putting Jim down, I'm not, I respect his opinion as much or more than anyone's, especially about 944's and Boxsters. I just like to get as many opinions as I can on a subject. Anyone else please feel free to add your thoughts. By the way, my car has 450 lb springs, and has a ride height of 5 1/4 inches at the front rocker panel. With a 28 mm sway bar.
Thanks
Bill Seifert
1987 944S Race Car
Geo told me a month or so ago that he was putting 600 lb springs on the front of his ITS 944. The stated reason was that the heavier springs kept movement of the suspension to a minimum and minimize the chance of breaking the already weak 944 ball joint. Geo, if I got any of this wrong, please let me know, as I am stating this from memory. (My memory is kinda short sometimes)
Anyway, I was talking to Jim Pasha last week, and he said that you should only use a max of 350 lb springs on a 944 for ITS racing, and I would assume this would apply to Class I PCA cars. As some of you know, Jim writes for Excellence, and knows the 944 well, and helped engineer a winning ITS 944 in Calif, some years ago. He said the reason for the ball joint failure is the extreme angle of the a arm when you lower the 944. He states that there is no reason to lower the 944 1 1/2 to 2 inches, as many of us do. He said it is better to have lighter springs and heavier sway bars, and only slightly lower the cars.
So, Geo, I was wondering what you thought of that advice. Please, don't anyone think I am putting Jim down, I'm not, I respect his opinion as much or more than anyone's, especially about 944's and Boxsters. I just like to get as many opinions as I can on a subject. Anyone else please feel free to add your thoughts. By the way, my car has 450 lb springs, and has a ride height of 5 1/4 inches at the front rocker panel. With a 28 mm sway bar.
Thanks
Bill Seifert
1987 944S Race Car
06-07-2005, 05:53 PM
#2
Race Director
Wow. I know Jim knows Porsche's and especially 944s and it's pretty brash to go against his advice, but I wouldn't take his advice on this matter for a second.
There are several things going on here. One is the old argument about soft springs/hard bars vs hard springs/soft bars. That's yet another holy war.
I will absolutely, positively, without a doubt, 100% disagree with him about the cause of the balljoint failure. If they can fail because of binding, it's a design flaw, not a function of lowering. In fact, the problem with them failing through lowering is too soft a spring. But keep in mind, if they can bind, even a stock ride height car can bind.
Think about this for a minute. Take out the springs and install struts with the body drilled out so there is no fluid and the rod moves easily. If the balljoint can bind a the top of the travel, it can bind at the top of the travel. Period.
Not lowering is one possible work-around to try to keep it from happening. The other is to install very stiff springs (especially if lowered). The net goal is the same - keep the control arm from reaching the highest point of travel where the balljoints bind. This is pretty simple monkey work. It's not even engineering.
BTW, Jon Milledge STRONGLY recommends running an ITS car at the minimum allowed height. Take that for what it's worth.
I will stand by my opinion. It's purely opinion as I'm still (grrrr...) building my car (although work has begun again finally). So, no, I don't have on-track experience with this car, but on the subject of balljoint bind anyway, it doesn't matter. As for the relative rates, it's my opinion based upon current best practices by professional racers in near-stock production-based racing. I'm not changing my mind on this one. In fact, I think I bought my t-bars (32mm) too small. I may end up with 34mm on the car before the first event with 650 lbs springs or more.
BTW, I'm not putting Jim down. I simply disagree with him and am stating why. I certainly don't have his experience with the car, but sometimes it's necessary not to do what all the other kids are doing. I know a lot of people who have been using significantly higher spring rates than they ever have to very good effect.
Also, one of the other reasons for using high spring rates is not only to keep the balljoints from binding, but to minimize suspension travel because with that much lowering you get into a nasty part of the camber curve usually and too much movement makes for hinky handling. The downside with a 944 of course is the rear t-bars are not something you generally want to try to change between sessions, so whatever you pick you're stuck with. Just pray it doesn't rain.
There are several things going on here. One is the old argument about soft springs/hard bars vs hard springs/soft bars. That's yet another holy war.
I will absolutely, positively, without a doubt, 100% disagree with him about the cause of the balljoint failure. If they can fail because of binding, it's a design flaw, not a function of lowering. In fact, the problem with them failing through lowering is too soft a spring. But keep in mind, if they can bind, even a stock ride height car can bind.
Think about this for a minute. Take out the springs and install struts with the body drilled out so there is no fluid and the rod moves easily. If the balljoint can bind a the top of the travel, it can bind at the top of the travel. Period.
Not lowering is one possible work-around to try to keep it from happening. The other is to install very stiff springs (especially if lowered). The net goal is the same - keep the control arm from reaching the highest point of travel where the balljoints bind. This is pretty simple monkey work. It's not even engineering.
BTW, Jon Milledge STRONGLY recommends running an ITS car at the minimum allowed height. Take that for what it's worth.
I will stand by my opinion. It's purely opinion as I'm still (grrrr...) building my car (although work has begun again finally). So, no, I don't have on-track experience with this car, but on the subject of balljoint bind anyway, it doesn't matter. As for the relative rates, it's my opinion based upon current best practices by professional racers in near-stock production-based racing. I'm not changing my mind on this one. In fact, I think I bought my t-bars (32mm) too small. I may end up with 34mm on the car before the first event with 650 lbs springs or more.
BTW, I'm not putting Jim down. I simply disagree with him and am stating why. I certainly don't have his experience with the car, but sometimes it's necessary not to do what all the other kids are doing. I know a lot of people who have been using significantly higher spring rates than they ever have to very good effect.
Also, one of the other reasons for using high spring rates is not only to keep the balljoints from binding, but to minimize suspension travel because with that much lowering you get into a nasty part of the camber curve usually and too much movement makes for hinky handling. The downside with a 944 of course is the rear t-bars are not something you generally want to try to change between sessions, so whatever you pick you're stuck with. Just pray it doesn't rain.
06-07-2005, 06:58 PM
#3
Three Wheelin'
Thread Starter
Geo,
I tend to agree with you. A friend went from 400lb springs to 550's, both with a 28mm Weltmeister sway bar. His car leans less with the 550's. I guess the ball joints will always be a problem, I have even heard of them breaking with Fabcar arms. With my old car, I changed the ball joints every year or so, but with the alum arms, that isn't possible. To other people, please chime in, I would love to get other opinions.
Thanks,
Bill
I tend to agree with you. A friend went from 400lb springs to 550's, both with a 28mm Weltmeister sway bar. His car leans less with the 550's. I guess the ball joints will always be a problem, I have even heard of them breaking with Fabcar arms. With my old car, I changed the ball joints every year or so, but with the alum arms, that isn't possible. To other people, please chime in, I would love to get other opinions.
Thanks,
Bill
06-07-2005, 07:30 PM
#4
Race Director
I totally agree that the balljoints will always be a problem on the 944. It is just plain and simple a design flaw that allows the balljoints to bind within the range of motion of the control arms. I suppose there may be a solution create a stop for the control arm somehow before it gets to the point of binding the balljoints, but it's entirely possible that would bring other problems. Nothing like your spring rates suddently becoming infinite in the middle of a corner.
I am not familiar enough with the Charlie Arms or Fabcar Arms (I've just admired the workmanship) to know for certain, but I'd guess they would HAVE to have the same basic problem and solve it through either an alternate balljoint with greater range of motion, or a spherical bearing with greater range of motion and a tapered pin to seat in the upright.
BTW, leaning, in and of itself is not bad. The delay in taking a set while the body moves creates something of a lack of responsiveness, but the steady state cornering is not necessarily compromised (because total load transfer is the same regardless).
Back to the balljoints, anything that could cause the control arm to reach the top of its range of travel (or however far it takes) to cause the balljoint to bind is BAD. This could be springs that are too soft, swaybars that are too soft, excessive lowering, or simply using the curbs (or any combination).
Something you might want to consider Bill is doing some non-destructive testing on the control arms. You cannot magnaflux them as aluminum is non-magnetic, but there are methods of testing aluminum similar to magnafluxing. This would at least give you some peace of mind concerning the condition of your control arms at whatever schedule you choose to test them (assuming you decide to actually do this). I have zero idea of the cost. I'm sure someone here does though.
I am not familiar enough with the Charlie Arms or Fabcar Arms (I've just admired the workmanship) to know for certain, but I'd guess they would HAVE to have the same basic problem and solve it through either an alternate balljoint with greater range of motion, or a spherical bearing with greater range of motion and a tapered pin to seat in the upright.
BTW, leaning, in and of itself is not bad. The delay in taking a set while the body moves creates something of a lack of responsiveness, but the steady state cornering is not necessarily compromised (because total load transfer is the same regardless).
Back to the balljoints, anything that could cause the control arm to reach the top of its range of travel (or however far it takes) to cause the balljoint to bind is BAD. This could be springs that are too soft, swaybars that are too soft, excessive lowering, or simply using the curbs (or any combination).
Something you might want to consider Bill is doing some non-destructive testing on the control arms. You cannot magnaflux them as aluminum is non-magnetic, but there are methods of testing aluminum similar to magnafluxing. This would at least give you some peace of mind concerning the condition of your control arms at whatever schedule you choose to test them (assuming you decide to actually do this). I have zero idea of the cost. I'm sure someone here does though.
06-07-2005, 07:33 PM
#5
Race Director
Oh, and as far as changing the balljoints in the aluminum arms, with rules changed to allow non-OEM replacement parts (that serve the same function as the OEM parts), I would think one of the aftermarket balljoint kits should be legal as long as they are not extra long pin (which would help to correct bump steer). You may want to look into the options currently available for replacing those balljoints.
06-07-2005, 07:38 PM
#6
Race Director
On my 944-spec car I run 350 lbs springs and 30 mm t-bars. We can run any front spring, but are limited by rules to the commonly avalible 30 mm t-bars. Our sway bars are free but most folks run either a combo of stock sway bars from turbo units to 968 M030 or Weltmeisters.
I run weltmeisters because I can adjust them.
I like to set-up so my springs are the bulk of my suspension and sway bars are for tuning the balance.
Now given my rules you can see why I use 30 mm rear bars. As for why I run 350 lbs fronts.
I figured that 30 mm bars are about 330 lbs/in wheel rate. A stock 944 suspension is pretty well balanced even though it is quite soft. So my aim was for a stock type balance between front and rear spring rates. So with 23.3 mm stock t-bar at 128 lbs or so I figured 350 would be good match for 30 mm-tbars.
I have found this to be the case and my car is one of faster one in the class. I did run previous set-up with 350;s and 28 mm t-bars, but found it had too much understeer in general. I could get ok balance by adjusting the sway bars, but it was band aiding the real issue of too soft a rear spring.
There are however some 944 spec guys that run from 250 lbs front spring to 450 lbs fronts. Mostly with 30 mm rear bars. These cars can be fast too. It appears there is no "right" set-up. When change the spring balance other things like sway bars and alignment play a strong role as well as driver preference.
Note that most spec cars are 2600-2570 lbs with driver. We have had 2 or 3 ball joint failures. While this may seem high this given all the cars (some 40+ prepared cars), alot of events per car, and most of these were the factory original units on old beat cars.
I run my car very low. I believe it is may be .5 to 1" under SCCA IT spec. I personally noticed much less body roll and more control after lowering the car that final 1/2 to 1". I have never had a ball joint failure, but do run stock steel arms with newish ball joints.
I run weltmeisters because I can adjust them.
I like to set-up so my springs are the bulk of my suspension and sway bars are for tuning the balance.
Now given my rules you can see why I use 30 mm rear bars. As for why I run 350 lbs fronts.
I figured that 30 mm bars are about 330 lbs/in wheel rate. A stock 944 suspension is pretty well balanced even though it is quite soft. So my aim was for a stock type balance between front and rear spring rates. So with 23.3 mm stock t-bar at 128 lbs or so I figured 350 would be good match for 30 mm-tbars.
I have found this to be the case and my car is one of faster one in the class. I did run previous set-up with 350;s and 28 mm t-bars, but found it had too much understeer in general. I could get ok balance by adjusting the sway bars, but it was band aiding the real issue of too soft a rear spring.
There are however some 944 spec guys that run from 250 lbs front spring to 450 lbs fronts. Mostly with 30 mm rear bars. These cars can be fast too. It appears there is no "right" set-up. When change the spring balance other things like sway bars and alignment play a strong role as well as driver preference.
Note that most spec cars are 2600-2570 lbs with driver. We have had 2 or 3 ball joint failures. While this may seem high this given all the cars (some 40+ prepared cars), alot of events per car, and most of these were the factory original units on old beat cars.
I run my car very low. I believe it is may be .5 to 1" under SCCA IT spec. I personally noticed much less body roll and more control after lowering the car that final 1/2 to 1". I have never had a ball joint failure, but do run stock steel arms with newish ball joints.
06-07-2005, 07:49 PM
#7
Drifting
If you want to inspect your aluminum arms you can do a dye penetrant inspection. The kits are available from Grainger, I like the red dye pen with the white activator, cracks show up very easily. The flourescent dyes (for use with a blacklight) are a little harder to see "in the field".
I was under the impression that the early steel arms were a bolt-on to later 944's, if this is the case it may be cheaper in the long run to change to the steel arms with replaceable joints. Replacement steel arms are dirt cheap.
I was under the impression that the early steel arms were a bolt-on to later 944's, if this is the case it may be cheaper in the long run to change to the steel arms with replaceable joints. Replacement steel arms are dirt cheap.
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06-07-2005, 08:00 PM
#8
Drifting
wow. 350# is a street/track compromise (i.e. DE) spring for a 951.
I can't imagine it would be a good race spring for a 944.
In fact we currently run 500# on our 2275lb. 944 lightweight...
I can't imagine it would be a good race spring for a 944.
In fact we currently run 500# on our 2275lb. 944 lightweight...
06-07-2005, 09:23 PM
#9
Race Director
Originally Posted by Cory M
I was under the impression that the early steel arms were a bolt-on to later 944's, if this is the case it may be cheaper in the long run to change to the steel arms with replaceable joints. Replacement steel arms are dirt cheap.
Personally, I think I'd do the NDT on a regular basis and investigate the aftermarket balljoint solutions. That, of course, is in addition to using a very high front spring rate.
06-07-2005, 09:40 PM
#11
Three Wheelin'
Thread Starter
Cory M, As Geo says steel arms are illegal for me in SCCA, but even if they were not, I believe they are shorter than the 87 up alum arms. I think you can put steel on a 1985 1/2 and 86, but they won't fit on a late car.
Keith, how the holy heck do you get a 944 to 2275 lbs? Nort Northam was going to go SCCA EP racing, even bought a fuel cell, but could not get the car to SCCA EP weight. He races HSR now.
M758, about what would a 32 mm torsion bar be in spring rate?
Thanks everyone,
Bill
Keith, how the holy heck do you get a 944 to 2275 lbs? Nort Northam was going to go SCCA EP racing, even bought a fuel cell, but could not get the car to SCCA EP weight. He races HSR now.
M758, about what would a 32 mm torsion bar be in spring rate?
Thanks everyone,
Bill
06-07-2005, 09:52 PM
#12
Race Director
Bill, check out Tech-Session (BTW, Skip has been awfully quiet the last year):
http://www.tech-session.com/kb/index...x_v2&id=22&c=4
This should give you some good info.
I might be interested in talking with Nort. If something doesn't happen to give the 944 a reasonable chance in IT I may go EP racing (but not in the near-term). I've been thinking that it might make a good EP car.
http://www.tech-session.com/kb/index...x_v2&id=22&c=4
This should give you some good info.
I might be interested in talking with Nort. If something doesn't happen to give the 944 a reasonable chance in IT I may go EP racing (but not in the near-term). I've been thinking that it might make a good EP car.
06-07-2005, 10:31 PM
#13
Addict
Rennlist Member
Rennlist Member
Hey;
I'm with Geo. Oh my God... I really said that!
350lb springs would be a real flopper. Soft springs with stiff bars will snap alloy arms at the sway bar mount! If you never let the angle of the arm reach the danger zone, it won't bind the ball joint. You can either keep the car high and soft, or spring it stiff. The stiffer you spring, the lower you can go. My car is at 25" at the fender lip. Not overly low, but the arms are still past parallel.
I personally would not have alloy arms on my 944. They a stinking POS right from the git go. The steel arms and early joints are MUCH more reliable, but as Bill did say, they are about 1" shorter than 87> alloy arms.
Fabcar uses a longer ball joint pin. This lowers the arm when you think about it, eh? It buys you back some of your arm travel before the joint binds. I myself have built my own control arms. The first version is a straight arm. If I ever get the time, the second set will have the ball joint mount plate angled at, say... 5 degrees to free up more pin travel.
I run 500F/450R full coilover for DE at 2500 & change. Car corners HARD. Next up is solid bushings... again, once I can find the time to get them installed!
I'm with Geo. Oh my God... I really said that!
350lb springs would be a real flopper. Soft springs with stiff bars will snap alloy arms at the sway bar mount! If you never let the angle of the arm reach the danger zone, it won't bind the ball joint. You can either keep the car high and soft, or spring it stiff. The stiffer you spring, the lower you can go. My car is at 25" at the fender lip. Not overly low, but the arms are still past parallel.
I personally would not have alloy arms on my 944. They a stinking POS right from the git go. The steel arms and early joints are MUCH more reliable, but as Bill did say, they are about 1" shorter than 87> alloy arms.
Fabcar uses a longer ball joint pin. This lowers the arm when you think about it, eh? It buys you back some of your arm travel before the joint binds. I myself have built my own control arms. The first version is a straight arm. If I ever get the time, the second set will have the ball joint mount plate angled at, say... 5 degrees to free up more pin travel.
I run 500F/450R full coilover for DE at 2500 & change. Car corners HARD. Next up is solid bushings... again, once I can find the time to get them installed!
06-07-2005, 11:25 PM
#14
Race Director
Originally Posted by RedlineMan
Hey;
I'm with Geo. Oh my God... I really said that!
I'm with Geo. Oh my God... I really said that!
Originally Posted by RedlineMan
Fabcar uses a longer ball joint pin. This lowers the arm when you think about it, eh? It buys you back some of your arm travel before the joint binds.
06-08-2005, 12:46 AM
#15
Drifting
Originally Posted by Bill L Seifert
Keith, how the holy heck do you get a 944 to 2275 lbs?
Bill
Bill
fiberglass hood and lexan are next.