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picking your brains guys,,

PSH said:
Morning all

I have had an issue on the car for some time now that in recent months has been getting worse and I'm stumped as to which of a number of things that it could be.

- The symptom is basically a very rough ride which is very dependent on the road surface.
- A perfectly flat new road and it's hardly noticeable if at all, add a slight worsening of the surface and the car feels like it's going over tiny cobble stones, the worse the surface the worse the effect.
- The ride feels far too rough, more so than anything that I've experienced before
- I have no noise, but rumbling/vibration not coming from any one spot, it's the whole car...

Look forward to reading your views
Pete



It can only be suspension, and not wheels or anything else.

Buckled wheels on the front usually give steering wheel kickback and vibes, on the rear they vibrate the front seats & chassis
Some Tyres especially with worn down tread blocks can give off lot of road noise on rough surfaces, but not vibrations coming from the
whole car?

It can only be worn / broken Springs and dampers, if wheel bearings are good etc..

R
 
Thanks, Roger, I will do a thorough check on everything once the car's up on the ramp....this has stumped me a little, I've had worn bearings, broken suspension components etc, etc,,,this is a feeling that I've not experienced in the car before...I've never had a broken spring, well not on a MacPherson strut so will look close at that..as I said there is no handling issue that I have noticed and two days ago I was driving at very and I mean very high speed at full acceleration...I didn't notice anything during that mad few seconds....

cheers

Pete
 
The difference in wheels & Tyres can be fairly substantial, I chop and change all the time and the audible difference from an 8x16 set with 215/50/16
R888 Toyos to a 6x16 set with 205/55/16 is a massive reduction in road noise and chassis & Suspension vibrations. Just like a top mount change from rubber to solid or a bush change from Rubber to Poly etc...the difference can be enough to annoy and ruin the driving experience.

I've seen many tyres over the years become "Noisy" mostly stemmed from incorrect Geo, or a buckled wheel which wears the tread irregular or sometimes
perished rubber that's gone hard because it's many years old and / or lack of use etc..
I've also had one shock absorber fail that seemed ok on a "bounce test", but having had vibrations through the steering wheel and then removed
the insert from the strut housing to find no resistance ! a replacement cured the issue.

R
 
Pete, I have a set of early offset teledials I could lend you if you wanted to rule out tyre/wheel issues. Would need to sort out a transfer spot though. I'm West of London (Farnham).
 
PhilKent said:
Pete, I have a set of early offset teledials I could lend you if you wanted to rule out tyre/wheel issues. Would need to sort out a transfer spot though. I'm West of London (Farnham).



Hi Phil
That's kind of you sir and a possible solution for testing to remove the tyres as a possible cause..I suspect that they are the main cause...they are Bridgestone SO2's which I recall my son advising against due to road noise and wet weather abilities when compared to the now de-funked Goodyear F1's previously fitted. Perhaps Bridgestone's go off much quicker than the Goodyear's and being a harder ride, to begin with, is just getting harsher than I'm used too...add the un-even wear on the front right doesn't help the situation either. I need to use the car this Sunday as it's my daughter's wedding and my son can't look at the car before hand so I'll probably let some air out of the tyres just for this day. If the car feels better it's another sign that it's the tyre's/wheels at fault. If I'm still stumped after my son's taken a look and re-balanced the wheels I'll be in touch to see if we can make a date to meet. If I can find the money and no sign of damage under the car I may just bite the bullet and buy a new set anyway, the car needs new tyres so it wouldn't be a false economy.

cheers

Pete
 
Bridgestone S02's are Directional which is a Noisy design that is being stopped, asymmetrical designs are becoming the norm now.
They also have a very stiff sidewall and are the worst to fit and remove, they are prone to going hard and perishing in time, If they
are over 5 years old there's a good chance this is what's giving you a non compliant harsh ride especially on poor surfaces.

Go for Goodyear F1 Assy' or Michelin Pilot sport's both have a much softer sidewall and will transform the ride quality.

R
 
I have just tried reducing the tyre pressures by 6psi all round, there is a noticeable improvement, I've only driven around town a short distance so far... I'll see how it is tomorrow when I deliver my daughter's wedding dress ready for the weekend, that's a motorway trip and one particular part has been very rough of late so I should get a good idea if the ride has indeed improved...fingers crossed..

Pete
 
Hi Pete,

this sounds promising. Hopefully turns out to be something around wheels and tyres as discussed before and doesn't go into top mounts/suspension ect, although I'm sure you are at a point that I would be by now that I'd just want to know where it's coming from so you could corrrect it!

my previous set of tyres where in fact the same as yours, Bridgestone SO2's and to be honest I didn't like them at all and they were up to now the only waste of money I've ever spent on any of my 944's.

its crazy but I remember spending just shy of £1000 fitted and I loved the look of the tread apart from where it blended into the side wall and the depth of the grip looked like I had alignment wear from new. I had a MOT booked in the very next day and used a different garage as I normally use my friends as I used to work there but this time his not station was ful booked. Anyhow the mot technician wanted to fail it due to tyre wear on the limit as I said above , and we were arguing that they were brand new and he didn't believe me so I showed him the reciept and he still didn't believe me so I decided to leave and book into my mates place.

i found them ok for dry grip at first but found they quickly followed the roads camber quite badly and wore uneaven within 6 months of casual driving. After the winter bringing the car back out the next time I had it in the ramp I found that the rubber had all gone hard and was full of splits/ cracks so I bit the bullet wanting to be safe becuase of the quickness of the car to order a new set of continental sports 3 and they are fantastic and I highly recomend them better road trip and quieter than the Bridgestones.

Im hooked on this brand now. On my non aspersted 944 I have always liked Michelin pilot sports very soft and low noise as Roger said and very grippy, but never used them on my turbo as yet.

Look forward to hearing any further info into what you find ??

Atb
Daniel
 
Thanks for the info Daniel and Roger....sorry Roger I hadn't noticed your reply before...probably due to using the phone....Daniel you have described my experience with the SO2's....I should have listened to my son at the time and avoid them. Roger...I have always prefered directional patterns..it's more a cosmetic thing than performance or ride...I don't really push the car hard enough around the twisties to notice a difference. Daniel...you did the right thing taking your car to another MOT station...the guy was an idiot...you can have a 1/3 bald and as long as the tread is over 1.6mm the tyre is legal...you may get an advisory if too bad though. My tyres are only 2 years old but they do look worn and feel hard...added to the front right which is getting close to being ilegal due to the past tracking issue..

Pete
 
a little more R&D... the motorway trip today was better but not by a lot... I have been trying to analysis when I get the 'rumble' and when not. The only time when it's gone altogether is under very heavy load..ie during fast acceleration spouts. If accelerating normally, cruising of on over run I can feel the vibration, the worse the road surface the worse the feedback through the chassis. I can not feel it through the steering, nor, from what I can tell, through the seat? it's very much an all over feeling, like being lightly shaken in a tin can. I may be able to feel it slightly through the pedals but this could just be my mind playing tricks. Putting aside the tyres which I know aren't helping and bearings, both wheels and torque as there is zero noise associated with this, I am thinking gearbox mount or perhaps CV's. Now I've had a CV joint fail before with the customary 'clink, clink' that increases with road speed so had discounted these but the fact that the rumble goes completely on full load is making me question whether there is play in the CV joints which of course is gone when fully loaded? I threw the car around some tight high-speed bands today, much higher than said corner is rated for and the car was solid, no movement or upset moments at all. There is zero tram lining that I have noticed too.
I'm thinking that I will take an extra close look at the CV's once up on the ramp, gearbox mount too..
I'll update what I discover when I can...
cheers

Pete
 
Hey Pete,,
Pretty sure you will get it sorted,,
A mystery soon solved,,,
I couldn't believe I hit high speeds with an alternator belt that was like two tiny strips of black string lol and a 3 inch screw embedded in one of my back tyres,,,,
Our cars are bullet proof,,,,
All the best,,,,,jasonp
 
Thanks for that Jason...

A small but important update...my son has just been home to unload his gear from holiday and get ready for the wedding tomorrow, he took a very quick look at the tyres, in fact from a distance he could see a difference in colour around the centre circumference...he pointed it out to me but alas I struggle to see dark things due to laser surgery. He then got me to run my hand around the circumference of the centre portion, remember these are directional tyres so have a defined centre, well let's just say that it was like running my hand over the Himalayas....there is a noticeable number of high spots like castellations and the tyre is rock hard. He has said all along that it's the tyres, I have been leaning that way myself in recent days as stated earlier, I'm now nearly convinced that it's the tyres and the tyres only....I will try to get a new set asap, my son is going to check availability and price next week for me....

fingers crossed

Pete
 
I was very surprised once before at the dramatic effects tyres could have - I put two new tyres on the front - I think they were Dunlops - and the rears were still OK at the time. The car suddenly drove like a reliant robin, and really did not feel safe at all. I went back, and had them checked, all OK, but nothing else had changed. Dunlop came back and said it could be a front/rear mismatch, and so change the rears - I wasn't particularly happy at the idea of buying another pair of tyres, of a type that had turned my car into something I just didn't want to drive, especially seeing as the existing ones were no where near worn out. In the end they agreed that if it didn't cure the problem, they would refund all four tyres, so I had little to loose. Sure enough, it solved the problem entirely.
 
Thanks, Tref, yours and other's experiences is giving me hope of getting the old girl back to fighting trim without costing me an arm and a leg, something I most certainly cannot afford these days.

cheers

Pete
 
It's looking very Promusing pete, we shall find out ones she has new shoes!

and at least it's something the car and you need anyway as I used to find the grip iffy in the wet once they developed hard spots ( which should never happen with a tyre this expensive and let's face it it's one of the top most expensive out there. And I forgot to mension, they said when they ordered mine that they have to be a porsche rubber and not the use Usual so2 s and I said are you referring to the speed rating, and he said no they will have to be speacial Lu ordered from porsche approved rubber or they would not be insured to fit them on any porsche?

I thought he he was having me on but he pretty much sent me away to buy elsewhere so I ordered them feeling robbed but happy they would be the best, but ended up the worst tyres and the most expensive I ever purchased.

Fingers crossed mate
 
Not sure yet ....will see what make my son can get a good deal on.....been testing the car more tonight mainly due to having to drive 70 miles fot last minute wedding stuff....althougj i would love it to just be tyres it feels more to me...when accelerating hard out of corners it feels to rough for just tyres....could be gearbox mount or cv too...i can feel the vibration through the gear knob, or at least o think that can....i'll be hsppy to get it on the ramp.....it's a shame as on tap this thing takes off like a missle...
 
Morning Pete!

I was having a think last night after reading your last post, and thought I'd mension the things I would check just incase any would be something you might not?

before I had it on the ramp I would:

• open the Bonnet and inspect the x4 top mount suspension bolts are tight to spec.

• Inspect Both engine mounts (splits ect) and check bolt tightness is in speck.

• at rear check top suspension nut and bolt are tight and in spec.

•on ramp•

•. check front cross member bolts are tight and in torque spec

• Check x4 front bell house bolts are tight and in spec

•. Check rear torque tube to bell house bolts are tight and in spec

•. Check rear torque bracket to body are tight and in spec

• check gearbox mounts are tight and in spec and condition if rubber.

•. Check the spline sleeve inside gearbox service hole that connects torque tube spline to gearbox spline is tight and in spec

•. Check control rear sway arm bolts and any movements up and down with a bar.

•. Check lower rear suspension to sway arm bolts are tight and inspect rubber that bolt goes through and try away bar up and down for any wear movement

•. check drive shaft bolts all round are are tight and in spec

•. Check calliper bolts are tight all round check with bar for any movement in hub to sway arms ect

•. Check all antiroll bar bushes ect for play and condition

•. Check exhaust bracket bolts to body are tight and in spec

•. Check all wishbone ball joint/bushes and bolts for tightness/condition and play with bar

•. Check wheel bearings all round for any up down left right play with wheel on first, then with bar if possible when just lifted off ground with king bar under tryre with bar on floor

•. Check steering rack bolts to chassis are tight

Check all exhaust bolts including downpipes to engine are tight / wastegate brackets also

•. Check radiator is tight on its brackets and play, also if possible give everythin a wiggle that could possibly knock on body in engine bay.


feeeeeeew......... Im sure theres more but these are the things that I personally would take an hour or so to go through once on a ramp. After that it's things like front top mounts which I'm not sure would cause a rumble throughout the cabin more of a intermitten bang on certain roads and bumps I would have thought through experience.

Then suspebsion springs cracked ect but possibly same as above on them?


all the best
daniel



 
Hi Daniel

Many thanks for the detailed check list. .I'll use it to hopefully stop me missing something....sorry for late reply....I'm away at my daughters wedding and only just found a few minutes to reply...

Cheers

Pete
 

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