[williamoss]

My 95, 968 M030 Limited Slip 968 That I bought from Pete (RS barn). I mention that fact as Pete did many modifications to the brakes suspension etc. But my problem is my front end feels loose. My tire pressures are all set to factory specs. My tires are all good with good tread. I have had a 4 wheel alignment. But when I drive on the highway at speeds of 50-80 mph it feels loose or jumpy. I will be driving along and all of a sudden the front end will move either left or right without me turning the wheels. Any idea of the possible problem?

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[mbardeen]

I can't say for certain as I don't have my 968 (yet), but I believe this is fairly well known issue with the car. Evidently it's especially prevelant on off-camber surfaces, where the car follows the surface regardless of what the driver is doing. Top Gear (the old one) did a review of the 968 where Clarkson complains of the problem.



Maybe those in the know will have a better answer than I.

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[flash]

tramlining is a problem with these cars. it is exacerbated by many things.



i would look at the age of the tires. as tires age they get hard. when that happens they tend to tramline more. it can start as early as 3 years. anything over 6 years needs to be replaced.



bushings are a real problem, especially caster blocks. if there are any fluid leaks, and the bushings are rubber, they can easily become swollen or damaged and result in a lot of steering issues.



the steering shaft u-joint is a known failure item.



tie rod ends tend to create problems like this.



too much toe will absolutely cause this. the car will constantly be trying to turn, and you will constantly be correcting. i see a lot of alignments that have incorrect settings. frequently this is because the rack has not been properly calibrated prior to use.



the less common causes could be worn ball joints, worn steering rack, worn steering rack bushing, yada yada

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[mdss]

The fact you say the front feels loose sounds like you are saying its light??

If so you may have seen my thread on vague steering at speed i am in the process of getting a new steering pump as when the pump has problems it has been suggested it can suddenly start feeling odd. In my case it can be fine at 70mph then suddenly it will become light or at low speed it is very heavy. I have no leaks from the rack etc.



I may be describing something totally different but thought i would give my 2 cents



I will report back once i have changed the pump.

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[bombfactory]

I have this issue as well - inconsistent steering weight/feel. I have replaced everything except the ps pump - resealed it, but haven't replaced it. I seriously hope this is the problem because there's nothing else left to replace!



My advice: Don't do what I did, replace the pump first!

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[rxter]

Yep - same problem. Feels light in the loafers at legal highway speeds. If you move to a less aggressive castor setting (more or less castor I don't recall) the tires will track better for you. If you do that you lose feel on high speed corners though so your choice.



When I notice this skating around on the freeway I correct it by using the right foot adjustment.

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[DaveN]

You live in OR, kinda like the roads of BC - Loggers! My car jumps at the oddest times but it's the tramlining from the logging trucks creating wells in the road surface with those million 18 wheels. Find a spot where your car does the funky dance, do a U turn and re-drive the same piece and see if it occurs at the same place in he road.

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[Langley968]

I have to agree with what Flash posted:



"I would look at the age of the tires. as tires age they get hard. when that happens they tend to tramline more. it can start as early as 3 years. anything over 6 years needs to be replaced"



When I bought my 968 two years ago, it had 5-6 year old Bridgestones and the tramlining was "scary" on the I-5 when I picked it up in Seattle. As soon as I changed the tires, the tramlining was gone. The tires I have now have a softer sidewall but there is no "light/vague" feeling up front any longer!

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[AJG]

Ah, we don't make roads anymore like the good old Romans! A particular stretch of road in Aberdeen which is heavily used has a dip in the middle of the lane. This has a scary effect on the steering. Its like someone yanks the steering away from your intended line, its almost unstoppable! Ergo, other road imperfections will have an effect on our babies from time to time. I believe there could be some truth in the aging tyre theory becuase I notice it more this year and my front tyres are down to about 4/5mm are are now about three years old, Just have a good bevy when you're finished driving, nothing like Dutch courage.

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[968Syncro]

[quote name='flash' timestamp='1323725001' post='119052']

the steering shaft u-joint is a known failure item.

[/quote]

Yup, same problem, tried a world class alignment, didn't help. But then I know I need new front tires -- at the alignment shop, that is exactly what they said, older worn tires can amplify the problem.



Flash, on the other hand, note the quote above. Can you please elaborate on this the u-joint problem? How could we diagnose a "failed" steering shaft u-joint? I assume it isn't a critical failure (breakage), but some type of wear or less tight u-joint. How difficult to replace? The reason I ask is I once had a "tight spot" in the steering; when the wheel was in a certain position, say 10 o'clock, it took more force to get it past that point, it was tight in both turn directions, and always at the same angle of the wheel. Therefore I suspected a u-joint problem, perhaps dirt. It went away over a year ago, long gone, it isn't present anymore, but I wonder...



Thanks!

Roland

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[flash]

the steering shaft has a u-joint where the angle changes. if that fails, you lose steering. when it starts to wear, there is slop there, and you get steering issues.



you can test the joint by merely putting your hand on it and rotating the steering wheel a bit and see if there is any play there.



"flat spots" are usually rack related, and are worn gears in that assembly. you drive the most in the middle, and consequently wear that spot on the gears first.

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[968Syncro]

Oh yeah, duh, of course the "flat spot" (always in the same place) could have been the rack. It wasn't a flat spot, but a binding, almost like dirt or crud in the gears, or a tight bearing or something like that. It started when I had the rack replaced, so there should have been no reason to suspect the u-joint would have gone bad at that exact time, but of course good reason to suspect the problem was in the rack. BTW, it was a ZIMs rack, the shop suggested one that was about $1,200 or so, refused the autozone rack, so we settled on the medium ground of ZIMs. I've had no other problem in the last 2 years. OK, I'll stop hijacking the thread here.

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[flash]

"flat spot" may not be the right term to use, but what i meant was a spot in the middle where the steering felt different than over the rest of the rack. it could be resistant if the gears weren't meshing right, or just vague if they were worn badly.

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[bombfactory]

rxtr - Yes, caster could also be contributing to the problem. My current alignment has about 1/2" more caster on the right as on the left. Too much difference I suppose could be screwing with things. I did notice an improvement in feel and grip when I recently installed a full set of Michelin Pilot PS2's, but the too-heavy steering weight in low to medium speed corners has remained.



968Syncro - An 'AutoZone rack' is a rebuilt genuine ZF rack, just purchased through AutoZone. I have one on my car now. The price is so low that you can't help but be suspicious, but it's legit. No leaks after a few thousand miles now.

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[mdss]

Hi



so just a quick update the pump will be fitted next week fingers crossed for me and bomb factory as if this solves it bombfactory will also have the solution to his problem also.

will let you know once it fitted

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[bombfactory]

If this works it will be a merry Christmas indeed!

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[williamoss]

OK I had the suspension looked at and all the parts under the car are 100% OK, i.e. the struts, power steering linkage, the tie rod ends, camber/castor blocks etc. I just called my alignment shop who suggested that if the tires are wearing evenly, which they are, the car may may not out of alignment, but it may be a tire pressure issue. He suggested to raise the pressure from 36 lbs (the recommended pressure) to 5% less than the maximum pressure on the side of the tires. If this does not work then he suggested I do an alignment.



What do you all think of this idea.

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[flash]

i think it's a horrible idea. that much pressure will do all sorts of undesirable things.



what were the alignment specs from the printout? these cars are extremely touchy about caster and toe set



how old are the tires? after 3 years tires start really getting hard and can start to do odd things. after 6 years they should be tossed.

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[bombfactory]

Fully agree with Flash on aging tires. My car had front tires dated 2006 when I bought it, so they were six-plus years old when I recently replaced them. And while the old ones looked fine and had plenty of tread on them with no unusual wear, they had absolutely no grip, which was immediately evident once they were gone.



My steering feel and response has improved, but the low and medium speed heavy steering weight is still there, though with a proper alignment still to go, I'm getting closer.



Pumping up the tires til they're rock hard will indeed lighten up the steering - I tried it - but the ride becomes too punishing (with my 18's anyway).

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[williamoss]

Tires are now just 2 yrs 3 months old. Pumped the pressure up to 45 lbs, max is 50 and the steering is better.

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