V2Rocket

the L/R is stamped into the end of the bar...you'd be grinding for a while to get rid of it

V2Rocket

my understanding is that depending on ride height, the steering tie rod can sit at a different angle (between crossmember and spindle) than the control arm.

(imagine this is turned 90* as it would be on the car)
stock ride height the control arm and tie rod look like: ||
at lowered ride height the ctrl arm and tie rod look like: |\ or /|

what happens here, is that when the wheel hits a bump and starts to travel up (compressing spring), the control arm and tie rod also move but will now travel in different arcs of motion. the control arm can only move up or down but the steering tie rod has left-right motion too...so a bump can make the steering wheel "bump" right or left.

i ran for maybe 8 or 9 years with the 1.25" weltmeister lowering springs and there was bump steer, but it's not terrible and you get used to it.

Noahs944

Ordered a new set of 28mm torsion bars, thanks to Spencer's suggestion... and now considering converting the struts to coil overs to help corner balancing & ride height. Not sure if I should go 250, 275 or 300 lb/inch coils up front... Googled bump steer solutions, but not sure on the best solution... please someone speak up if you know of solutions.

MAGK944

You were on the right track for a daily driver but now you have moved away from your original plan. Those 250 Welts with a 1.25in drop up front and a set of 28 torsion bars and same drop at the rear will do you well for a daily driver. You do not have to worry about correcting the a-arm angle or bump steer, they are minimally affected.

Coilovers and corner balancing on a daily driver is not required and really a waste of time and money. If you fit front coilovers only, set and then adjust them again lower than the Welts you planed on buying, you may not have sufficient height adjustment at the rear to easily level the car, unless you reindex the bars. Reindexing the bars is a pain, you really don't want to be in that position more than once on a daily driver. On anything much lower than the Welts you will also risk serious damage to your a-arms and you don't want those failing on the highway.

If you go low on these cars you need to think about a-arms that can take longer ball joint pins and that will keep the a-arms parallel to the road. At that point bump steer become an issue and you will be looking at methods for keeping your tie-rods parallel also.

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.

Noahs944

Great feedback MAGK944. Thanks!

Braymond

Hello Noahs944. What is your use case here? Are you just street driving and looking to improve the handling of your car or do you have some track time in your plan.

I just acquired a 944S recently and I've been scouring this forum for info about updating the suspension too. I am planning to set my car up for auto cross, DE, and maybe a SP3 or Chump eventually.

Keep us posted on your results.

Bill

924srr27l

http://www.elephantracing.com/suspen...4bumpsteer.htm


R

924srr27l

Hi, I don't agree with this, more so especially if every corner has been changed, modified, lowered and everything needs setting up etc..
(4 wheel alignment, Geo & ride heights)


Corner weighting near 555lb's on each corner (on y car) has in two words made the chassis "Incredibly Balanced" and if as many on here the car is being designed and modified for hard street use and not just trips to the Mall, then it does benefit having a well set up chassis besides many members also do track days also.


Of course it's dependant on how fussy and particular people are, and again there's a fair amount of members here that go to great lengths to extract as much performance as possible.






My arms are not parallel at all but higher at the ball joint end, does somebody make a specific kit for the stock aluminium A arms, or is it a new complete arm?



R

MistaX

Completely disagree. Spending money to upgrade a suspension but not spend a tiny bit more to actually get it working 100% right? You're changing everything on the car. Balance it. If your side to side weights are off the car will take lefts better than rights, or vice versa, and they can be far off pretty easily.

MAGK944

Coilovers and corner balancing on a daily driver is not required and really a waste of time and money.

Like I said, you will do your own thing regardless of what my experience has taught me or what others more experienced than me will advise you to do.

Do you really think that after perfectly corner balancing the car, taking into account the weight of the driver and half a tank of gas, you are going to notice any difference using the car as a daily driver on a public road? Maybe on 1% of your daily driving you can push it a bit around some twisties and even then you will be nowhere near what you push these cars on a track.

...and herein lies the problem. Like I said those 250lb and 1.25in lower Welts do a great job on a daily driver matched with 28mm torsion bars, new bushes and uprated arb's. Here is someone much more experienced than me telling you the same thing <Clarks Garage> and v2 on this thread basically said the same. Also Weltmeister must have done their development and research back in the late 80's and determined that any lower than 1.25in would probably compromise the control arms. In truth you can go a little lower but they must have built in a safety margin, very wise! So, you want to go even lower and fit yourself some coilovers on your daily driver. What will happen is your control arms will not be parallel to the road like Porsche recommends in all their 944 technical manuals and this will cause undue stress to your control arm ball socket and they will fail.

So you fit longer control arm ball joint pins or different control arms to correct this, there are a few solutions out there. You will now notice your steering feels off and that is because your steering tie-rods are now not level. So you fit some sort of bump steer correction, again there are a few solutions out there.

Now that you have something that is at least as safe as stock, when the car left the factory. Start experimenting with different spring rates. Don't forget that when you fit different poundage springs you will have to account for the length of those springs to maintain the adjustment range on your coilover dampers, so get your calculator out. You will also have to reindex those torsion bars and corner balance again. Repeat the whole process again and again until it is just perfect, trust me you will always find fault and feel the need to tweek.

So well done, you are now good to go on your racecar inspired daily driver and have the maintenence requirements of a track car to prove it. Have fun on your drive to work!

...or take the best and simplest solution offered to you by many more experienced than me on this forum. GL


A solution from one company for early steel arms:
<longer control arm pins>
<bump steer correction>

thomasmryan

Being cheap, I set my ride height such that I can still use my existing floor jacks. (-20mm up front and -30mm in the rear with 10 gallons of go juice)

Noahs944

Thanks mate. Those look well built.
-----
Magk944,
I think you understand the situation well.
Regarding the coil over conversion (seen here http://www.ground-control-store.com/...p/II=77/CA=219) I wasn't going for this with the intention of making it lower than 1.25" but just having another means of tweaking rather than the TBars.

Your argument is sound and to be fair to the stock 944, I think it handles great on the streets, but way soft for Autocross... the 250 lb/inch will easily be an improvement.

JustinL

Noah, if you don't have the front springs yet, we have a spare set we can sell you for a good price.

924srr27l

GL


Thanks for the Ball joint and Bump steer links,

Sorry is all of the above directed at me and my car, or the OP? or both ?


R

MAGK944

Just me ranting on, apologies if it seemed directed at anyone, not meant that way.

OP simply wanted some basic suspension upgrade advise for a daily driver that escalated to coilovers, high spring rates, geometry correction, all of which was confusing the issue and way beyond what the op asked for. I just wanted to bring everything back to earth and explain what was best for the question asked.

btw the work you are doing on your car is quite awesome!