The story so far. Used to get a little judder at around 90mph on P6000s. Got the wheel balances checked. All were OK. This mild judder didn’t bother me much since I don’t drive at 90mph (very often).
Since the P6000s were nearly out of tread, I fitted new Rainexperts all round. Balanced etc. Now much heavier shake, now between 60-70mph and mild shake between 30-35 and 90ish.
Could it be, with the Rainexperts having a softer side wall, that the original 90mph shake is now emphasised at 60mph, being a subharmonic of 90mph?
Just wondering what the correct sequence of fault finding diagnosis would be to locate the problem? I don’t want to waste time and cash replacing suspension parts unnessasarily. (I would just replace all bushes, springs, ball joints and shocks just to experience “as new” handling, but I can’t afford it)
As far as I know the spring and shock set up is standard and probably as old as the car.
Any suggestions, (or hands on help from anyone in the Watford area), would be very much appreciated.
Hi Tony, so what’s it like at 180mph only joking (!!) but I think the tyre thing is a red herring and it may be the same problem or just getting worse. Tyre balancing machines are very good and it’s unlikely you’d have 2 sets that were bad. So a bent wheel possibly, certainly worth swapping them around. Then the propshaft balance or a UJ on the way out, worth getting it on a ramp and having a good tug.
We have a judder over 50mph on our Vectra 2T. Had a broken rear spring sorted, but judder persisted. Turns out to be slight buckle on inner rim of wheel on side of broken spring, which probably happened on same pot hole impact (not that I know exactly when it happened).
Irmscher 19" GT-Stars - expensive and not easy to find a replacement so hoping I can get it it sorted, but just wondered if a damaged wheel could be your problem. You can see a slight flat spot on th rim and wobble on my wheel when you spin it free, very little but enough to cause the judder at speed. !"£$%^& Pot Holes!
Just a thought also, if you have aftermarket wheels be sure the spigot hole is the correct size, and the inserts are fitted if they use them, as they ensure the wheel is bolted up true.
Any damage on the rims would be spotted when new tyres where fitted unless the fitter has a white stick !!As above check driveshaft ,possible track rod end or balljoint play,misaligned
Thats interesting, my scuttle shake got much worse after I fitted Rain Experts. I hadn’t tied the two events together until you mentioned it. Food for thought.
They are the standard 14 inch Eunos 7 spoke, but its the first time I’ve used them, so definitely I’ll check them for run out and roundness. Also roundness of the new tyres can be checked at the same time, as I’ve heard of out of round tyres in the past.
Something I’m going to try tomorrow which could eliminate or not the tyres soft sidewall issue, is to put a higher pressure in them, say 30 or 32 (just for test purposes) to stiffen the sidewalls and see if the speed at which the shake occures changes. I don’t expect the tyres are the fault but just amplify the problem at different speeds.
Began some checks today. All wheels and tyres appear to be running true with no ‘run out’ or bent rims on the outside or inside. The tyres are not out of round. The springs as far as I can tell are not broken. Gave all wheels a good shake in the vertical and horizontal planes and couldn’t detect any play in the bearings. Couldn’t find any play in the steering.
Need to get under the car to check for driveshaft play, as suggested, and to get a crow bar on the wishbone bushes (although Simplyred, in another post, advises that worn bushes didn’t cause any shake in his case).
Any other suggestions, or if any knowledgable member in the Herts, Bucks, Beds area can give any hands on help in locating this problem, I would be very grateful.
Were the wheels balanced dynamically? Is there a knock on weight on the inner rim and stick on weights inside the wheel near the spokes, or knock on weights on the inner and outer rims?
Knock on weights on the inner rim and stick on near the spokes. I remember the the guy adding the weights, then spinning them up a second time and adding more. I assume it was dynamically. I watched them being spun on a machine, but having said that, I had a SAAB wheel which couldn’t have stick on weights because of lack of caliper clearence, so they balanced that statically by flicking a switch on the same machine and using knock on weights on the inner rim only. Unfortunately I don’t know enough about wheel balancing machines to know if all the settings are right by watching them. I know they have to be set to the wheel size but thats about all.
Trawled around some Miata forums and they talk about scuttle shake between 60 and 70mph. Apparently a well known occurance. Only some cars get it and some cars get it only with certain combinations of wheels and tyres.
Their way of dealing with it, apart from experimenting with different makes of tyres, ( a luxury I can’t afford) is to get the wheels “road force” balanced on a Hunter GSP9700 advanced wheel balancing machine, to less than 15lbs. Who’s got one of them!!?? This reduces the effect and sometimes eliminates it.
Since as good a wheel balance as possible is recommended, I decided to get a second opinion on the back street company who fitted and balanced the Rainexperts originally.
I happened to be in Maldon and went to Supertyres who host North Thames Region tech days, which I’ve previously attended.
They found the fronts to be 20gms out of balance, and weights on opposite sides of the circumference!
Just as an aside I asked Martin to do a full alignment on their new Hunter Hawkeye. He had previously set it up for “standard road” about 2 years and 11k miles ago on their previous Hawkeye. Suprisingly all the angles were still in spec!
So. The bottom line. On the way home the skake was greatly reduced and about half the time was not detectable. I can live with that.
Lesson: I bought cheap (wheel fitting and balancing) so I bought twice.
The Rainexperts have only done about 1K miles so they may stiffen up a bit. I didn’t get the problem with 5 year old P6000s which must have been quite hard in comparison. They used to make a lot of road noise, which the Rainexperts don’t. I’ve read that Rainexperts are a little soft on the sidewalls and I’ve noticed that the steering is a tad less sharp. Nothing to do with alignment since this was OK.
Thank you eveyrone for your suggestions. I’d be interested to know if anyone else has had similar experiences.