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924ssr27l, if you were not happy with the answers supplied then take your own measurements and calculate to your satisfaction. This might be a good time for you to help the community.
It's nothing to do with not being happy with the answers, it's more how have they been achieved ?
Why was the one axle shown not squared and the other was and why would a different angled version (924) and wishbone length be declared as making "no effect" by Mikeaudiogeek then he contradicts his comment with "the main effect is the angle of the strut " !!
Of course I won't be relying or do rely on these comments on a forum, but Sometimes unqualified people do understand the principles and it's interesting to discuss and also learn from them, but a lot of the time this info comes from what people have read and pass on which doesn't actually mean they understand 100% themselves.
When further deeper questions are asked, but they are Ignored (In my case for days) and Not replied to this further confirms the originator of the comments only knows some information but not 100%
If something is quoted wrong it doesn't help anybody or a community does it?.
MAGK944 Please stop highjacking this thread, the op has his answer, bought the parts and has probably fitted them and is enjoying his car.
The OP Noahs944 has asked several questions throughout this thread in regard to lowering his car, asking about
- do strut lengths need to be shortened?
- match ability on front & rear spring rates
- Alignment
furthered with "what is your suggestion as an anti-bumpsteer device?"
and a good attempt to answer my query regarding some figures and calculations quotes with " Rotational Leverage, no? " to which nobody replied.
Others members brought up and discussed Delrin and Poly bushes and
corner weighting also came up when you declared
"MAGK944
Coilovers and corner balancing on a daily driver is not required and really a waste of time and money"
I see a bit of a pattern when you've told the OP: "I'm sure you will do as you wish but imo there was nothing wrong with your original plan apart fitting new bushes and upping to 28 bars at the back like v2 suggested"
As you also told me: "I gave you advise earlier in this thread and I said you would probably ignore it and do youir own thing anyway, which you did."
So unless I'm mistaken? I would of thought Noahs944 would of been able to reveal his own frustrations to me if HE felt I or anyone else was as you put it "Hijacking his thread" ?
This may be the case, but I don't want to hear it from you, or your comments on nobody is taking your advice and doing there own thing anyway!
Start you own thread about the "exacting figures" you seem to need to perform what is, at best, a guesstimate anyway.
Accurate Figures and explanations will assist on this thread and all threads nicely ? there's no need to label this thread as non accurate and suggest open another one if accuracy is required?
I gave you advise earlier in this thread and I said you would probably ignore it and do youir own thing anyway, which you did.
I'm not sure exactly what you refer ? or how it is you know what I'm doing or have done? to quantify I've done my own thing ....on what?
In truth each car will have slightly different figures anyway depending on wheel offset, ride height, camber, weight, etc.,
Sure, but there must be stock figures for the 924 and later 944 / 968
The 2 main wishbone types / lengths.
Does a stock car and a 30mm lowered car have different Motion ratio figures ? Do different Camber settings change the motion ratio ?
(This is the type of questions I'm interesting to know how this happens & works)
Now lets add the fact that coil spings are made to a nominal number and an acceptable tollerance standard of +/-10%.
I'm using Hypeco OBD coils which have a guaranteed 2% tolerance
Angle Correction Factor (ACF). For the 944 its around 15 degrees at the front
Ok, is this the early or late cars?
Finally consider that all your static balancing and calculations mean very little in real life, they are a basic starting point at best, nothing more so dont get too caught up in it.
I'm not looking for a balanced setup, the current springs on the car now are not the same front & rear rates.
The best suspension advise I have seen on this forum is from Chris White .
Ok, interesting info for me, I'm sure also to many others (inc the OP), otherwise I could be churlish and suggest your hijacking his thread !
The first piece of advice is to ditch the T bars. unfortunately the way Porsche chose to use them in the 944 makes them a problem. There is no easy adjustment for height and its very time consuming to change the bars for different spring rates. Corner balancing a 944 with T bars is a very time consuming effort…and not much fun!
He's obviously experienced some ball ache here with the T bars,
However I have quick change Elephant Racing T Bars which can be whipped out and re-indexed or replaced quickly, the spring plate also has minor ride height adjustments, so I'm not so anti T bars as it's not a pain to change and adjust these.
All I wanted in this thread were some explanations and if they are not pinned down to one number but a range so be it.
Front & Rear 924 / early 944 v Late 944 / 968
Ok You've seen .92 to .96 for the front, thanks and the rear is .42
But now you've also mentioned other things can change these figures and I'm curious to understand how & why they do this (Camber, ? ride height etc..)
Please stop highjacking this thread, the op has his answer, bought the parts and has probably fitted them and is enjoying his car. Start you own thread about the "exacting figures" you seem to need to perform what is, at best, a guesstimate anyway.
You have been given good figures by others here to use for your calculations, so use them or do your own measurements. I gave you advise earlier in this thread and I said you would probably ignore it and do youir own thing anyway, which you did.
In truth each car will have slightly different figures anyway depending on wheel offset, ride height, camber, weight, etc., therefore the only way to figure your "number" is to measure your car. However, in parctise it will not make any differnce when you do measure your car and use your figures. For example I've seen figures from 0.92 to 0.96 quoted for the front MR and guess what, they are all correct, so pick one or do your own specific meaurements. If you calculate your own number it still is relatively meaningless as there are tollerences in effect beyond your control. I shall demonstrate, lets see how it works out with 250lb spings using two extreme MR's:
250*(0.92^2) = 212 WR
250*(0.96^2) = 230 WR
Now lets add the fact that coil spings are made to a nominal number and an acceptable tollerance standard of +/-10%. So the first calculation for wheel rate could be anywhere between:
For 250 nominal springs: 225*(0.92^2) = 190 and 275*(0.92^2) = 232
I think you can see where I am going here. However, iof you really want to calculate your own number for MR, it is relatively easy. The number is simply the cosine of the angle of your strut , its otherwise know as the Angle Correction Factor (ACF). For the 944 its around 15 degrees at the front and what do you know, cos15 = 0.96
Finally consider that all your static balancing and calculations mean very little in real life, they are a basic starting point at best, nothing more so dont get too caught up in it. Dynamically, the way you drive and how you like the car to handle will affect things much, much more. Its a personal thing.
Appologies to everyone reading for the long post, I will continue to bore you...
The best suspension advise I have seen on this forum is from Chris White a few years ago. I keep all of these posts and take notice of them. I am posting it here for everyone to take note of as it a good a place as any for some expert advise:
Chris White , 11-03-2012 09:59 AM Time to debunk another old ‘myth’…. Choosing the ‘best’ spring rate is not a math calculation to get the same rate for the front and rear. People get caught up in the ‘perfect 50/50’ balance concept. In reality it just doesn’t matter that much. In fact for the best grip you want a rear bias for braking and acceleration – people that like to poke fun at 911’s for their heavy rear bias don’t understand that under barking with a lot of weight transfer the 911’s end up with a nice balance and those of use with static 50/50 balance end up very nose heavy. Look at classic racing 911s –close to the same rotor and caliper size front and rear. Then when its time to accelerate the 911 transfers lots of weight back to the driving wheels….and the rest of us have to deal with tire spin! In a track situation a well driven 944 should only have an actual 50/50 weight distribution when it is parked. If you are driving well you should be either accelerating or braking – not coasting. SO, in reality you need to select the best spring rate for suspension control for each end of the car and then use sway bars and other technics to balance the car. There is some grey area here, you can ‘t go way overboard with different rates front to rear. Most well set up club racers end up with full coil overs running 6-800 front and 600 rear. 600 in the rear seems to give the best balance of stiffness to reduce roll and suppleness to absorb road surface variations. The front spring rate is more determined by driver style and preference. I have seen fronts set up at 600 – 1200 that give good performance. If you do the math you can see that this is far from the ‘balanced’ approach that the typical equal effective rate would dictate. As for street set ups – the nice balance I have found is a closer to equal than the track set up. 350/550 spring rate feels good to me – but that really depends on the condition of the roads in your area. 350/550 over expansion joints is obnoxious. On smooth paved roads its nice. A good piece on news is that springs are relatively cheap – try a couple out and see what works for you.
Chris White , 11-07-2012 09:50 AM The first piece of advice is to ditch the T bars. The torsion bars are a nice theoretical solution since they do not add any unsprung weight to the suspension; unfortunately the way Porsche chose to use them in the 944 makes them a problem. There is no easy adjustment for height and its very time consuming to change the bars for different spring rates. Corner balancing a 944 with T bars is a very time consuming effort…and not much fun! The problem with the ‘helper’ spring concept is that it can only raise the rear of the car (unless you reindex the torsion bars). You also will end up with an interesting situation where you have a dynamic difference in spring rates from one side to the other. When cornering you are compressing the Torsion bar and helper spring on the outside wheel but on the inside you are relaxing only the torsion bar (the helper spring will be rattling around on the shock with no effect on the suspension). Its not a huge problem, but it does make the sway bar deal with multiple effective spring rates. If you ditch the torsion bar you can change the rear springs in under 30 minutes, and that is pretty handy compared to half a day to swap or reindex torsion bars! Another thing to keep in mind when looking at spring rates that have been used by other people, especially track people; the main reason you see production cars use high spring rates for track use is to limit the movement of the suspension. The more you allow your suspension to deflect the great the camber and toe may change. On cars with not well developed stock suspensions the change in camber can be quite significant and the best way to control it is by using very stiff springs so that the suspension will not move from the static position. If you look at a picture of a 944 cornering hard on a track you can see that the inside front wheel has horrible negative camber and is usually scrubbing the inside shoulder of the tire. Look at the pictures to see this in action (the Garnet Red car is a picture of my street car from 10 years ago running the 350/550 combo with 2.5 degrees of negative camber and weltmeister sways – it still shows inside front bad habits! My advice would be to keep the 400 fronts, ditch the Tbar and go with 600 rear coil overs.
attachments
Chris White , 11-07-2012 10:35 AM
You may be able to calculate the best ‘theoretical’ spring rate…but that does not equate to the best spring rate in the ‘real’ world. I know that some of the readers get all bent out of shape when I say that, but the ‘real’ world has to take into account track conditions, weather conditions, driver style and other intangibles that are not in the theoretical world. If there existed a track that was as smooth as a pool table with absolutely no imperfections I would set a 944 up with very high spring rates. The 944 is a street production car and as such has a suspension that displays unwanted (for the track) characteristics through its range of movement. If the track is very rough (like Bridgehampton before it closed) you need a much softer spring rate to avoid skipping down the track! Braking into the heal of the boot at Watkins Glen does not work well with a very stiff suspension – and it can’t be fixed by just tweaking the shocks! Dry vs rain….big difference in spring rates. Driver style – smooth vs overly aggressive, trail braker vs hard turn in…. Tires – brand new Hoosiers or 30 heat cycle Victoracers. Suspension components – solid vs rubber bushings. Way, way too many factors in the ‘real’ world to be able to calculate the one best spring rate. You can calculate a good starting point but that’s about it – or you can see what has been working for other successful drivers/teams and start with that set up and fine tune it to your needs.
Slow progress but this was today. After reading clark's garage description of torsion bar upgrade method... the "how to" guide. I was very disappointed. Wanted to sell the 28mm T-bones & perform a delete then go to a coil over set up.
Instead of following the Clark's method of installing then removing, then installing, then removing, and possibly repeat; I did what seems most logical to me. The KISS method. Perhaps this is flawed thinking, if so, please speak up & save me some troubles.
Before removing the side plates from the assembly I scribed the angle of the side plate.
Then followed the side plate's projection until the intersection of the x-y axis represents the wheel base & ride height while on the bench with no load or tension... Measured 6.25" ride height reference with the 22mm T-bars. moved the new HD T-bars until the measurement was 5" (lowering the ride height by 1.25" which is the same as my coil springs up front.
I repeated this, on the other side, both being identical. Then the plan is to set the eccentric bolts to the middle - neutral position and from the rest the car on the ground and fine tune with the eccentric. Then once ride height is good, get a proper alignment.
with a larger rear bar, the weight of the car will settle the rear less. ie static height would be higher if you indexed at the same angle. you might go 4.75" or a 1.5" drop then fiddle with the eccentric.
some 911 guys have some fuzzy math videos or look at the angle change in the 968 wsm which shows a 5 degree swing from usa specs(14*) to club sport (9*). that's from memory so don't hold me to it))
Yep, they now seat on a couple of aluminium thick washers that act as end stops.
With the thicker T-bars they will settle less so unless you're lucky to get it right on the first try you will have to do the same thing every one of us did, take off, adjust, reinstall...repeat..until exhausted and annoyed but ride height is on point.
Slow progress but this was today. After reading clark's garage description of torsion bar upgrade method... the "how to" guide. I was very disappointed. Wanted to sell the 28mm T-bones & perform a delete then go to a coil over set up.
Instead of following the Clark's method of installing then removing, then installing, then removing, and possibly repeat; I did what seems most logical to me. The KISS method. Perhaps this is flawed thinking, if so, please speak up & save me some troubles.
Before removing the side plates from the assembly I scribed the angle of the side plate.
Then followed the side plate's projection until the intersection of the x-y axis represents the wheel base & ride height while on the bench with no load or tension... Measured 6.25" ride height reference with the 22mm T-bars. moved the new HD T-bars until the measurement was 5" (lowering the ride height by 1.25" which is the same as my coil springs up front.
I repeated this, on the other side, both being identical. Then the plan is to set the eccentric bolts to the middle - neutral position and from the rest the car on the ground and fine tune with the eccentric. Then once ride height is good, get a proper alignment.
Is it going to work?
Uh, needless to say, I have a differing opinion than a lot of what was quoted on this page.
But anyway,
Measure back about three inches from the outer end of the spline receiver. True your mark around the circumference.
Remove a total of 3/8" including the amount of the width of whatever blade you cut with.
Weld on a 3/16 plate on each half.
Drill two (or more) holes on the inner plate and tap threads.
Drill two holes in the outer plate and elongate them.
Fab up a thread adjuster with a bolt and welded nut.
The other two bolts lock your adjustment.
T
Last edited by 951and944S; 08-28-2017 at 09:28 AM.
Before removing the side plates from the assembly I scribed the angle of the side plate.
Then followed the side plate's projection until the intersection of the x-y axis represents the wheel base & ride height while on the bench with no load or tension... Measured 6.25" ride height reference with the 22mm T-bars. moved the new HD T-bars until the measurement was 5" (lowering the ride height by 1.25" which is the same as my coil springs up front.
What you need to know is what that angle is when the suspension is loaded.
The difference between that angle and the unloaded angle will be half that with the 28mm bar. You then have to account for that "half amount" with your unloaded position with the new bar. That will get you close(r).
That sounds similar to what we did. I think I measured from the bolt that holds the top of the banana arm to the eccentric bolt on the spring plate (before disassembly) to get a rough idea of where I wanted to be when I put it back together. Scribe line works as well but keep in mind that your 'resting' position will be higher than original because the car will sag less as you drop the weight back onto the wheels. On ours, the difference between 23.5mm bars and 28mm bars was about 1/2".
We made the mistake of not setting our eccentrics to the middle before indexing our torsion bars. We were able to even out the small difference with the adjustment we had left but we are now maxed out in adjustment, so if we want to lower the car by a small amount all around we can't. We are running around 5" overall ride height with driver and a full tank of fuel.
Originally Posted by morghen
reinstall...repeat..until exhausted and annoyed but ride height is on point.
Uh, needless to say, I have a differing opinion than a lot of what was quoted on this page.
But anyway,
Measure back about three inches from the outer end of the spline receiver. True your mark around the circumference.
Remove a total of 3/8" including the amount of the width of whatever blade you cut with.
Weld on a 3/16 plate on each half.
Drill two (or more) holes on the inner plate and tap threads.
Drill two holes in the outer plate and elongate them.
Fab up a thread adjuster with a bolt and welded nut.
The other two bolts lock your adjustment.
T
Interesting T,
Is this as a method of adjusting height?
Thank you all for your responses, I appreciate the intel!
Last night I removed all traces of park brake. This will reduce unsprung weight. I will later make a lock for my hydraulic handbrake once that is plumbed in.
Painted the tube. One day, far from now... my 944 will be pristine underneath and above. It will take years of driving in the rain to get rid of the mud and dirt accumulation. Luckily I really enjoy driving in the rain.
I welded the ends of the tubes back on. I don't think the slide hammer technique for pulling t-bars is in the cards for me. I tried drilling and tapping my torsion bars. My drill bits wouldn't cut it!
01-26-2017, 04:48 PM
