Lowered 944s and shattered ball joints

[John Sims]

As you will note from the Brands Hatch News thread, we now have experience of someone on the forum shearing a lower ball joint. This is possibility is more likely in lowered cars driven enthusiastically.

The problem is that, under braking, the suspension compresses such that it goes beyond the travel of the ball joint. []

Many, myself included, have considered that the only way of avoiding this is to fit exotic lower wishbones, Charlie Bars or the like. Wonderful, only I don't have £1,000+ for such exotica, particularly after coughing up for Big Blacks and new struts (and cameras and lenses).

However, I discussed this with Gerald Web at GWR (07960 031 060). GWR are principally a race team who also do Porsche servicing and track day support - advert on the PCGB wall calender that you all threw in the bin. They have raced 944's in the past and seem to know what they are talking about.

I had an idea, that wouldn't cost me £1,000, and ran it past Gerald. Apparently they have a proven solution which wasn't 1,000,000 miles away from my thoughts. Obviously it would be unfair to discus this solution directly on the forum but if you would like to give Gerald a ring I am sure he can book you in for the modification. He is only 6 miles away from me so you could also drop in for a coffee.

Tell Gerald I sent you...I might get a couple of quid off Beaky's next bill. []

 

[Diver944]

Sounds interesting John, I look forward to seeing it in action when we all go to Donington on 4th April

 

[sawood12]

Can anyone advise just how low the car has to be before it starts to cause a problem? For example my car is running on standard and unmolested suspension at the moment but it does look quite low - maybe the old suspension is sagging. Therefore how do I know if i'm anywhere near the danger zone, especially on track where the car is leaning over considerably? Also when I upgrade to KW the car will be lowered and again how do I know if i'm in the danger zone?

Alternatively if this solution you are referring to on this thread is relatively inexpensive the it might be worth getting it done in conjunction with the suspension upgrade as a precaution.

 

[John Sims]

I don't know but I would think this is a reasonable indication:-

http://www.pcaucr.org/site/page.jsp?pageid=222

It would think it very sensible to have the suspension modified at the time of any revision, particularly if that revision included lowering the font of the car.

I don't believe the modification should be very expensive, but should at least be cheaper than smashing the car up.

 

[Hilux]

`kin `ell [&:]

Promax rang me today to sat that the KW V3 kit is on the car as are the Weltmeister ARB`s [8D] (Update to follow)

I dont intend lowering the car by much (if at all) but I assume if the rear torsion bar is re-indexed (which it has been) its due to a different ride height OR due to different spring heights in relation to the new suspension (may be one and the same[8|])

Fen

What do you think as you have a similar set up?

I will post this to Andy and Roger for their comment also.

 

[sawood12]

Fen mentions a 35mm drop (see link below, 2nd note from the bottom). I think this is a pretty significant drop looking at how low my car currently sits and I personally think it sits us squarely in the danger zone based upon Peter's opinion that he didn't think his car was significantly lowered.

http://www.porscheclubgbforum.com/tm.asp?m=252907&mpage=4

 

[Big Dave]

Paul
The 944,s have to be re-indexed at the rear to account for the springs on the KW,s.
If it wasnt lowered in this way your car would look like a mk2 cortina with a jack up kit fitted...[8|][8|][8|][:'(][:'(][:'(]

Once the stuff is on the car youl need to tell the promax boys what finished height you want it B4 they re-alighn it, otherwise as soon as you start messing about with the ride heights afterwards it will mess the alighnment up...Trust me ive been there.. 3 alighnments later...!!!!!!!£££££££££££

 

[333pg333]

Yes you will need to lower the car through re-indexing but that's fine. They look and handle much better this way too. This does, however bring the ball joints into question and while you're in there the hubs have been failing too under duress but this is more a 'while you're down there' option. Going to the link that John posted shows Markus' solution which would be a little easier than the Charlies or RacersEdge ones that I have, in that you won't have to tap the spindle to accept the bigger and longer pin. Markus seems very thorough and highly experienced with Porsches in correspondence I've had with him (I'm getting his total clutch,pp, flywheel setup) and I would not hesitate to recommend him if you are looking at one of his products. I have no affiliation with any vendor either. []

 

[John Sims]

I understand the GWR modification is fairly extensive, and race proven, but isn't necessarily going to be easily within the budget of skinflint 944 owners. If you want the best, you have to pay for it.

However, I have also been considering other alternatives. As I understand the ball joint shears primarily when you try to twist it beyond its limit of travel; so you could reduce the possibility of failure by reducing the amount the suspension compresses. It occurs to me that the cheapest solution is to install bump stops on the dampers. These are available from Demon Tweeks, among others, at about £20 a set. It may take several on top of each other to limit travel to a safe level, and I doubt they would last more than 12 months, but they must be worth considering.

AFAIA There is no bump stop on 944 front suspension, aside the springs fully compressing and the ball joint snagging, so IMHO some form of bump stop can't be a bad thing. Note that conical springs will compress further than cylindrical springs as well.

Please discus. []

 

[Diver944]

ORIGINAL: John Sims

Please discus. []

I think I'll just pay someone to do it for me [8|]

I never realised there were no bump stops on the standard shocks though.

 

[John Sims]

ORIGINAL: Diver944

......I never realised there were no bump stops on the standard shocks though.

[&o] That'll be part number 951 343 527 00 then........I'll get my coat.

But [8|] If there is a bump stop then a second bump stop will last longer [] and this means only one extra will be required. [].

In fairness to GWR a bump stop would only limit the travel where as GWR control and accommodate the travel.

 

[Hilux]

Paul
The 944,s have to be re-indexed at the rear to account for the springs on the KW,s.

Thats what I thought.

My 951 is lowered and the TB re-indexed accordingly however note that the KW has built in bump stops and much stiffer springs both of which drastically limit the travel. The Weltmeister ARB`s also prevent excess travel all of which are why I have gone down this route although the original post did alarm me somewhat even though there are cars with all of the above running around.

I discussed with Andy at Promax who stated that they had never seen a broken ball joint. Worn ones yes but never a failure. He also confirmed that the KW V3 operates within the required travel limits even when lowered and it is not an issue.

Apparently it is extreme nose dive/squatting under braking in and out of corners etc that loads the suspension more than the design allows when the cars are lowered but without restricting the travel accordingly.

Apparently early non turbo cars have a different part ref for the lower arms/ball joints so this `could` be part of the issue. It may be that the car in question is lowered, doesnt have Mo30, possibly has alternate suspension (possibly without bump stops) and probably/maybe still has the older arm/balljoint?

Also to be noted is the fact that Mo30 is fully adjustable and can be adjusted considerably lower than the normal ride height so Porsche wouldnt have equipped the Mo30 cars with adjustable suspension that took the cars past their design parameters?

Discuss.................[]

 

[Hilux]

Mind you I`ve just found this

Interesting that the W/meister bars are an additional issue (apparently)

I have to say that it appears that the catastrophic failures seem to be lowered cars that are ragged rigid regularly IYKWIM

Promax always inspect arms/balljoints and I`m told mine are as good as new.

 

[edh]

Peter's car is a Lux (sort of), with Leda suspension - I've noticed it certainly rolls more than mine ( 250 turbo on Leda/Eibach ) & I guess dives more as well.

I don't think you want to be hitting bump stops during braking or cornering, wouldn't that make the car unstable?

Hartech claim to have never had a failure with their rebuilt wishbones - maybe they are a cheaper and reliable option?

 

[ross255]

Just get the ball joints replaced with these,

http://www.rennbay.com/geometry-correction-ball-joint-kit-p-36.html

Being longer balljoints, they stop the arm going to such an angle. Easy solution that would well enough for 99% of people.
Oh except for people trying to sell you £1000 arms, then I am sure they would tell you how bad and unsafe they are.

 

[sawood12]

According to the link in Hilux's note it seems that the failure mechanism is well understood and can be spotted prior to failure by two indentations in the rim of the socket in the control arm. Is it not therefore possible to take a dremmel to the control arm and simply grind indentations into the rim to provide clearance for the pin? As long as the ground indentations are are a smooth arc with a good final surface finish there shouldn't be any cracking issues post mod.

It's also worth noting that the indentations are at the front and rear of the socket which confirms the previous comment about it actually being the action of diving under braking and rising under accelleration that causes the problem rather than body roll, in which case the indentations would be outboard and inboard.

Just been pricing up the total cost of the KW installation and it has put the frightners up me!! I'll be watching with interest how John gets on with his Koni set up - although I still don't think i'll get away without re-indexing the rear TB's especially since i've made up my mind I want to replace them so I may as well go the whole hog.

 

[Hilux]

Oh except for people trying to sell you £1000 arms, then I am sure they would tell you how bad and unsafe they are.

I`m inclined to agree.

The solution? Reduce the suspension travel when lowering your car.

I don't think you want to be hitting bump stops during braking or cornering, wouldn't that make the car unstable?

Absolutely......however they are there as protection so as to prevent the geometry operating outside the design envelope but if you are hitting them regularly then firmer springs and possibly harder damper settings are the answer as your suspension travel is to long.

Peter's car is a Lux (sort of), with Leda suspension - I've noticed it certainly rolls more than mine ( 250 turbo on Leda/Eibach ) & I guess dives more as well.

Also a bigger/heavier engine?

 

[Hilux]

Just been pricing up the total cost of the KW installation and it has put the frightners up me!!

I`m not overly flush BUT I looked at aftermarket options (I personally dont like Koni`s) and the main option was to have my Mo30 rebuilt for circa £400 requiring new springs (35mm lowered type) required if yours are still the originals for circa £250?? (roughly £650 so far) then you`ll still need to reindex the TB so add £600 in parts plus labour for what is still an admirable set up but is still a soft road option.

The Ledas are circa £800 and you`ll still need to reindex the TB.

I chose the KW`s following UK/USA recommendations. They are inherantly reliable, completely rebuildable, fully and easily adjustable, non corroding and will transfer from car to car as required. They also have a residual value if sold on which is why I consider them v good value LONG TERM. I also consider that a knowledgeable purchaser (should I sell the car) will pay a small premium for my set up. If not I take it all off, lower the Mo30 and its no issue (It was especially a no-brainer when I drove, albeit briefly, Fens car where I was gobsmacked at how it completely transformed the feel and poise and balance of the car)

Thats my reasoning anyway as to why I saved and took the plunge.

I had it all fitted which will save a DIYer £500-£600 ish BUT even then it will have to go to a specialist to be set up properly which will cost £250+?? anyway as it needs to be driven and fine tuned and not just a static corner weight/laser set up (which is all that some specialists do)

I felt that going down another route I would be well over £1000 for the original set up anyway (albeit refurbished or brand new) and circa £1800 when you take into account that in my opinion you `should` fit 968 castor mounts at this stage, it will need professional setting up and the reindexing will possibly require new rear supports.

Note: I may have miscalculated a few bits but its no going back now..........[&:]

 

[John Sims]

ORIGINAL: Hilux

I don't think you want to be hitting bump stops during braking or cornering, wouldn't that make the car unstable?

Absolutely......however they are there as protection so as to prevent the geometry operating outside the design envelope but if you are hitting them regularly then firmer springs and possibly harder damper settings are the answer as your suspension travel is to long.

My view entirely. Bump stops do have some give but, the idea is the car bottoms on the bump stop, not at a point where it is wracking the ball joint. You only need to control/stop the travel to a point just short of ball joint full travel. The suspension isn't going to compress any further than ball joint full travel without breaking the ball joint any way. The bump stop should be the last point of movement before you break something.

Obviously on a car with standard ride height it shouldn't be an issue, unless you brake or corner with sufficient enthusiasm to fully compress the suspension. If the suspension is soft and saggy, through age, this could perhaps happen.

On a lowered car, obviously, there is less travel to play with. But, on the plus side, the springs are likely to be newer and stiffer so perhaps less likely to fully compress.

Either way, cars compress their suspension on cornering and braking as the weight transfers through driver in put. You can only transfer as much weight as tyre traction will allow. This being the case the odds are, if the car reaches its bump stops at all, it will settle onto them rather than crash violently down as perhaps others might be suggesting.

I was wrong earlier in saying 944s don't have bump stops. I subsequently confirmed that they do. [&o] All I am suggesting is there may be merit in in renewing and perhaps extending, that bump stop facility slightly as perhaps the original design didn't offer quite enough retardation if you were compressing the suspension to its full extent regularly. Equally, polymer technology has moved forward in 20 years and it could be that modern bump stops will give more progressive retardation.

 

[John Sims]

ORIGINAL: ross255

Just get the ball joints replaced with these,

http://www.rennbay.com/geometry-correction-ball-joint-kit-p-36.html

Being longer balljoints, they stop the arm going to such an angle. Easy solution that would well enough for 99% of people.
Oh except for people trying to sell you £1000 arms, then I am sure they would tell you how bad and unsafe they are.

I like the look of these, especially as I have a pair of redundant wishbones with u/s ball joints lurking in my shed.

I think I might have to have a set of these and rebuild the wishbones any way.

You still need bump stops though, because your suspension has to stop compressing some where. []

Edited 'cos I have just ordered some. You will no doubt get to hear how I get on. []