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Lowered 944s and shattered ball joints

ORIGINAL: Hilux
Just been pricing up the total cost of the KW installation and it has put the frightners up me!!
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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..........[&:]
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I agree and this is where I got to with my analysis. I have just underestimated the work involved in re-indexing the TB's and the fact that in all liklihood it will require the replacement of the rear TB tube mounts at near as damn it £100 each, so i've underestimated the total cost. I have decided I definately want to replace my rear TB's so even if I were to replace with standard the cost of the TB replacement would still be incurred. I don't see the point in refreshing the front shocks and springs and only the rear shocks. I've definately set my heart on KW's and in my head i'm 99.9% sold on them despite the cost but i'm still keeping my options open until the point I take the plunge!!

Also on the basis i'm planning on doing more track-days fitting standard is out of the question.

Back onto topic, where can you get your control arm ball-joints rebuilt? I thought there are only a handful of places that would take the plunge as it's a pretty delicate operation.
 
I've never liked the standard setup with its ability to bind and bend/shear the pin. It was something I was never very comfortable with on my car, going with the "it's never happened to anyone" reasoning to allow me to drive the car rather than being too scared.

Likewise I'm not overly comfortable with any of the refurb kits - I don't know specifically of any problems, but it's too important a component to kludge and that's sort of how I view the self-fit kits. The engineered solutions by Hartech and Gilmours' I'd be more comfortable with, but they don't avoid the inherent binding problem of the original design.

In terms of aftermarket arms at $1,500 a pair they are comparable price wise with new Porsche arms, which doesn't sound too bad to me. Add to that the fact they replace the bushes in the crossmember with Rose joints (a big plus for me, but not for everyone) and that they change the geometry so that not only don't they bind but they also maintain a correct wishbone to horizontal angle on a lowered car to keep the suspension working correctly with a lower ride height. I still intend to get some.
 
ORIGINAL: Fen
.....In terms of aftermarket arms at $1,500 a pair they are comparable price wise with new Porsche arms, which doesn't sound too bad to me. Add to that the fact they replace the bushes in the crossmember with Rose joints (a big plus for me, but not for everyone) and that they change the geometry so that not only don't they bind but they also maintain a correct wishbone to horizontal angle on a lowered car to keep the suspension working correctly with a lower ride height. I still intend to get some.
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Given an unrestricted budget I would go for after market arms but, regrettably, that isn't the case.

To go back to the Rennbay kit, I am now starting to scratch my head and would welcome your thoughts:-

The kit includes an extended ball joint pin. If the pin is 20mm longer and your spring/strut 20mm shorter, isn't that one and the same - you just have 20mm less suspension travel. Where is the advantage in that? I must be missing something here?
 
The way I see it the only way you can solve this problem is by increasing the diameter of the ball to give you the range of movement required. I can't see how lengthening the pin is going to improve the situation at all. You can't insert a larger diameter ball into the standard arms as you would have to increase the diameter of the socket in the arm and would probably thin the walls of the socket too much. Like Fen says, the only way to solve the problem is to upgrade the arms. The question that is in my mind is under what conditions does the ball joint's motion extend into the danger zone? If it is only during extreme track use then people who only use their cars on track occationally and do not drive their cars to the absolute limits while on track might be perfectly fine.
 
ORIGINAL: sawood12

........The question that is in my mind is under what conditions does the ball joint's motion extend into the danger zone? If it is only during extreme track use then people who only use their cars on track occationally and do not drive their cars to the absolute limits while on track might be perfectly fine.
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I believe this to be the case otherwise ball joints would have been shearing all over the place since 1986.

However, if the car is lowered the possibility/probability of the car bottoming and entering that danger zone is increased.

I further believe that Porsche aren't stupid and if your front bump stops are in good condition these will/should prevent the car from reaching that point of danger.

I am given to wonder if Peters ball joint may have failed because his KWs weren't calibrated to accommodate the correct bump stop position and, as a result, allowed suspension travel beyond that which the ball joint could accommodate.
 
John
As far as im aware Peters car is on LEDA,S.????
Are you having a "senior" moment.[:D][:D][:D][:D][:D]

If they are KW.s ,then they come as a package , incl the poly bump stops + correctly calibrated springs....

Peter.
What spring rates are you using Pete.???
As a few posts ago somebody mentioned your car seemed to roll somewhat...????
How old were the ball joints / wishbones.???
I hope the "incident" didnt cause too much damage.??££££££££
 
Right! I've been in correspondence with Travis at Rennbay and the mod does work.

Not quite the way he explained it but here we go:-

You lower the car by reducing the spring length - say 20mm. As a result the end of the wishbone is 20mm higher relative to the bottom of the car and the wishbone assumes a different angle to the ground.

If you then put that 20mm back under the axle the car is still 20mm lower than standard but the overall length of the strut is still the same so the lower wishbone is still in its original position, is still at the correct angle relative to the ground.

Now how does this help stop ball joint binding? Well.

Say the original strut binds at 8" compression but the bump stop stops it at 7½". On the new system, because the car, is lowered 1" you now only have 6½" of travel before the bump stop. But, because the ball joint is at the same angle that it was originally, the ball joint still has 8" of travel. [:)]

It works, it is simple but brilliant, I love it.
 
ORIGINAL: Big Dave UK

John
As far as im aware Peters car is on LEDA,S.????
Are you having a "senior" moment.[:D][:D][:D][:D][:D].....
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Yes, but you see where I am coming from.

TBH I do see Leda as a bit of a cottage industry, so wouldn't be surprised if they hadn't done that calculation in respect of limiting travel.

I would expect KW to get it right.
 
John
Have you ordered a kit.??
If so which one. The 19mm or just a extended 17mm one.???
I might be interested in a kit aswell....Save on postage etc..????[;)][;)][;)]
 
I have ordered mine already. I went for the 17mm diameter, geometry correction kit but with solid bearings over polymer bearings as standard.

If it does what it says on the tin I think it should be a good upgrade for lowered cars.

Even if, ultimately, what it says in dollars is what you pay in pounds it seems reasonable.
 
Hi Dave,

The spring rates are 300 for the fronts with 150 rear helpers.
I am considering uprating these, they are a great compromise but I fancy going a bit further even if it is at the expense of road manners.

I don't think my car rolled much, at least it felt fine inside and looking at the pics on Rick's site I think they show that too. The car was slightly lower than standard but nowhere near most modified cars. This was because the torsion bars were left alone when the suspension was fitted, the rear had sagged a little so the helpers bought that back up nicely.

The wishbone on that side was old, I'm not sure when or if it was changed, I cannot spot it in my records. The other side was changed fairly late last year after some play was found (and given that most circuits are clockwise it is understandable that this has the harder life. The one that failed did not have any play and given the expense I decided to hold off replacing it till this year when the car was due a full alignment and a few more tweaks. In hindsight this was a very stupid false economy.

When it failed I was running the dampers at their max setting, the brakes were biting very hard (I think I was very close to the tyres max deceleration for the first time that day) but the nose did not feel like it was dipping heavily.
 
Peter,

What camber and caster angles were you running?

How much lower than stock is your ride height?

 
I was just about to try to explain things as you did John - the point of the longer pin is to restore the correct wishbone angle which has all sorts of benefits around getting the suspension to work as designed but at a lower overall setting.

I'll be interested to see how the Rennbay ones go. Someone (I think from Titanic) has had high wear rates with their original geomtry ones on a standard car as I recall; the guy with the S that has an S2 front who's name I forget.
 
Further comment from Travis @ Rennbay:-

You are not just correcting the binding issue on the ball joint but you are correcting the
suspensions geometry. Since the control arm moves in an arc and not a
vertical line, the further up it goes the more it pulls the wheel in towards
the car. This is a progressive motion, meaning, the further it moves from
center line the more it pulls in per mm of movement. By having it start
(standard pins) in an already elevated position you are having much more
pull in during suspension compression. By making the control arm flat again
(GCK pins) it makes the pull in ratio the least that it can be.

BTW, the more the wheel pulls in the more positive camber the wheel is
given. This is called the "camber curve."

Anyway, just some more insight to the kit. I am sure it will work great for
you.
 
ORIGINAL: John Sims



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. [:eek:]
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Hi John,

I rebuilt my N/S control arm with the standard kit some time ago, the parts are very good quality and Travis is easily contactable should any installation issues arise. One thing is to make sure that when you insert the bushes into the control arm ball joint pocket, is to ensure that they are sitting squarely otherwise the ball pin will push the bush out of the pocket.

Regards

Dave K.
 
ORIGINAL: John Sims

Right! I've been in correspondence with Travis at Rennbay and the mod does work.

Not quite the way he explained it but here we go:-

You lower the car by reducing the spring length - say 20mm. As a result the end of the wishbone is 20mm higher relative to the bottom of the car and the wishbone assumes a different angle to the ground.

If you then put that 20mm back under the axle the car is still 20mm lower than standard but the overall length of the strut is still the same so the lower wishbone is still in its original position, is still at the correct angle relative to the ground.

Now how does this help stop ball joint binding? Well.

Say the original strut binds at 8" compression but the bump stop stops it at 7½". On the new system, because the car, is lowered 1" you now only have 6½" of travel before the bump stop. But, because the ball joint is at the same angle that it was originally, the ball joint still has 8" of travel. [:)]

It works, it is simple but brilliant, I love it.
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Well that explains it then, i'm sold 101% I love these simple solutions to apparently tricky problems. So how do you determine whether to go for the 17mm or the 19mm extention?
 
I think you might find the 17mm or 19mm refers to the diameter not the extension.

Ball joint shafts are 17mm as standard.
 
ORIGINAL: sawood12


Well that explains it then, i'm sold 101% I love these simple solutions to apparently tricky problems. So how do you determine whether to go for the 17mm or the 19mm extention?
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I think Travis recommends the 19mm for track applications as it has a stronger tensile strength, however you need to modify to hub to accept the thicker shaft.

Regards

Dave K. (Home after a 2 hour drive to cover 30 miles :(, who needs traction control !)




 
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