924Board.org

[ptheskil]

AFAIK (you bored of me doing this yet) the web address needs to end in ".jpg" to post the image inline with your message. I usually just post a link. BTW, when I follow your link I get page not found.
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1981 931 series2 Euro spec

[musicalannette]

AGGGGHHHHH!!! .JPG BFYC FLWA with mostly swearing at the computer! Thanks for the tip!

Right!! you need to check distances of A = B and when you manage to get this the same by adding shims you then need to make sure the rack is level C = D to the same datum. As you can see the left hand side (looking from the driving position) is smaller than the right.







You might find it easier to use the crossmember mounting points as a datum.












These two values need to be the same, thus you need to shim the Left Hand Side.






This works well with his type of crossmember, I am not sure the crossmembers with angled bracketts at 45 degrees have the same problem? The guy with the 45 deg. angled crossmember says he doesn't have bumpsteer so maybee they sorted it for that type.



MAKE SURE THAT THE RACK IS ALSO ALIGNED WITH THIS DATUM.

To do this check out the first picture for measurments C and D.




As you can see this is a fix that can be done for washers!!!! or with four washers!!!








While your at it, it makes good sense to add a jubilee clip to the steering rack as one gaiter is only held on by a small amount of friction in it's locating slot (very poor), its a bit of a fiddle as the moulded rubber isn't ment to have a clip, but I think it's worth it.




When I have a free day I will do a new post with caster camber guage manufactuer and usage for about £15. Not 4 wheel laser aligned I know, but handy if your messing around trying to find and dial out this kind of rubbish.
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

[ideola]

Ummm. 931 has same rack as 924. Not sure what you meant by that comment up there...
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erstwhile owner of just about every 924 variant ever made

[musicalannette]

Sorry, I have edited the post above, what i am trying to say is, if you have to move the rack up or down to make the distances C and D the same, it is possible using the existing holes and mounting points on the 924 2.0. If you look at the guys 931 photo's, as he rightly pointed out, the rack has different mounting plates on the crossmember, which means the crossmember IS different. He says there is no bumpsteer, I believe him, so I would assume the two holes for the track control arms are drilled at the same distance from chassis rails.
I am unsure what a 944 crossmember looks like, someone has said they are cast aluminium on later vehicles? I'm sure if you had a few cars to verify this shim value on you could buy some plate mild steel to correct this value without the need to measure the distances A and B, but you would still need to measure the rack distances C and D. Of course it is best if you can get the rack centralised and the inner ball joints at the correct point on the rack as per the Haynes manual. If you have the tracking correct with these other two correct, you don't get bumpsteer. Even if you don't get the steering rack at it's central position and get the tracking right and have the steering rods the same lengths, the amounts of bumpsteer it has will be massively reduced. To the extent most people probably won't notice it. Most cars are not perfect. Even from the factory.
I must admit Dodge had it right with the Viper set-up in their factory, where they check the alignment whilst moving the suspension up and down.
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

[ideola]

Hmmm...this might only be an issue then on pre-78 models, because according to PET, the cross member for 1979-onward 924 NA and 931 are all the same, part # 477.407.321.G. The 1978-prior is the same number but different suffix: 477.407.321.J.

Now, I have never owned a 924 earlier than '79, and I can personally attest that I have swapped cross members between NA and 931 cars with absolutely no issue whatsoever...
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erstwhile owner of just about every 924 variant ever made

[musicalannette]

Ermmmm.... that is interesting. I have a 1983 2.0 non LUX!

I am only going on what I can gleen from the guy with the 931 from Essex.
Do you remember if the mouting points were vertical or at 45 degrees?

I will also take a couple of quick photo's to show the whole assembly is off to left!! Again, I have no doubt my car hasn't been in an accident as the elctroplating is still in place. I DO wonder, if the part numbers are the same, that for either the 45 deg mounting and the vertical mounting crossmember that there is no distinction as far as porsche is concerned. I DO know the holes for the track control arms are drilled slightly off on my car. If that type of crossmember is Jig machined then all of that type will have the same problem. It IS Right Hand Drive. ther is only one guy from Canada to confirm the side alignment as a problem (his is Left Hand Drive).

As I said, I will take a few photo's tomorrow to show what i mean about the assembly being off to the left, It's a really quick and easy check without getting tools out or even having to bend down. Only hope I can figure the photo uploading out!!

If ANYONE who reads this and checks there car would please post "age" and "type" of car with comments "same" or "not the same" and a comment of "45deg" or "vertical" for the crossmember, it might help others to decide if they have the same problem. It will be really clear after the next set of photo's. Just in a rush and forgot to take them today!
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

[!tom]

78 924 vertical, has been in a crash in the front, which may explain the rubbing problem.
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78 924 NA
5-lug

[musicalannette]

If you take the flat of your hand to the top of the arch at both sides of the car at the front and measure to the sidewall of the tyre, I found the Left hand side tyre to be nearer my hand than the right.

Left Hand Side



Again from above.






And now the Right Hand Side.



And again from above.




As you can see there is clearly a problem here!!! the crossmember has NO natural movement in its holes and slots drilled in it to allow for this error!! I cannot say that other slightly differently designed crossmembers are the same. But it's a quick check. How many people are off to there car to have a look now!![/url]
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

[musicalannette]

Hi,

I saw a 924s in the car park of a local supermarket at the weekend and had a quick check with my hand against the tyre, it has the same discrepancy with the wheel closer to my hand on the left compared to the right. I had some decent clothes on and my better half was none too happy about not getting the shopping done so I did not get down to check the crossmember type howerver, just thought you might be interested.
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

[musicalannette]

I have just seen a thread on here, where a guy is rebuilding his 924 turbo (931) and the rack mounting is the vertical on the crossmember, his was an '81.

So I would guess that Porsche or Audi (depending on how or who setup the production line) had the crossmember sub-contracted out for delivery to the factory, and maybee some 924's an turbo's have the the rack mounting at 45 deg, some have the upright mounting, I am taking an educated guess that there are no part number distinction between the two, but one sub-contractor had slightly different drawings to the other, and one contractor and a jig problem(the one who made my crossmember with upright mountings).

They should have had them built at the rear wiper motor factory to avoid problems.

Anyone who has stripped a rear wiper motor will know i'm having a bit of a joke here, if the stickers inside are still intact.
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

[musicalannette]

I have also bee reading a few other posts where guys who lower there suspension are apparently getting bumpsteer, if all your suspension joints are in the right place, things are symetrical, and the toe-in is adjusted correctly, then this should not happen. What will happen though, is the static toe-in will be greater than originally palnned.

Let me explain, firstly, bumpsteer occurs when the the suspension or steering joints are not symetrical or if they are not same lentgh, it becomes really bad if both faults are there.

When the car rises and fall on it's suspension the toe-in thrust vectors are not the same left to right and the car wants to go left or right over a crest and the other way in a dip. CONSISTANTLY. If it does not always go the same way in a dip or crest then its not bumpsteer. The best way to check is in a straight line over dips and crests holding the wheel perfectly straight checking where the car goes as you drive over them.

Now with the standard 924, the way porsche has set it up, is to make the steering arms parrallel to the road with the suspension at rest, at that point porsche has the toe-in at more or less at 0, if you compress or relax the suspension, the horizontal distance between the steering ball joints (between the inner rack ball and the track rod end) reduces and the toe-in goes up.

Now, if you lower the car and try to set up the tracking (set it to more or less 0 at rest), the steering arm is no longer at it's longest horizontal length, so when it compresses the toe-in will go up (fine) but when it relaxes the toe-in drops (below 0 to a positive value, which is bad), and once you have toe-in past 0, the car will have poor stability and will probably want track off in one direction or the other.

This is not bumpsteer.

Luckily there is an easy fix, if you set up your tracking when the car has it's steering arms horizontal (like Porsche intended), by jacking the car up WHILST setting up the tracking, the toe-in will never drop below 0. It will mean your car has more toe-in forces while running straight and level and it will probably scrub front tyres a bit more quickly than intended, but if your steering doesn't have any manufacturing faults and everying is symetrical as it should be, you won't have any bumpsteer either. Hope this helps identify any problems you may have from lowereing the car. If you lower the car, with the car suspension at rest, the toe-in value must be higher to avoid Toe-out whe you go over a crest.

Don't confuse instability with bumpsteer.

If there is room, you might be able to raise the steering rack a little on the crossmember to reduce these errors, but again the rack must be measured against the car chassis as a datum to avoid any asymetrical pivots, and if you cannot raise the rack until the steering arms are parallel to the ground, you will still have to jack the car until you steering arms are both parallel to the ground WHILST setting up the tracking to the correct spec. Every mm you can raise the rack until the arm are parallel with the ground will reduce the excess toe-in from having lowered the car.

Hope this helps.
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....