Question regarding wheel weights and vibration

[speed freak]

Tell me about it! Its really weird and its intermittent so its not there all the time or not bad all the time. Some days it will do it others it wont. Im concerned about the alignment and thought it may be a cause, what part of the alignment could cause this? (camber/toe/castor)

It has been there since I bought the car, got new tires etc then I got coilovers fitted and everything was nice and smooth firm but much smoother then the old suspension, thought it could have been worn shocks. Drove around like that for one full week without an alignment then went back to mx5 plus so they could check ride height and check to see if all was tight still, everything checked out. While I was up there I got a wheel alignment done. When I was driving around for the week after the installation I couldn't feel any vibration or shake or wobble but after the new alignment its back.

I got 1 deg negative camber on front 1.5ish deg negative camber on rear, 1.6mm total toe in front and rear and just over 7 deg castor in the front. That is my latest alignment and it drives nice but it vibrates again after this was done. Im getting another done soon to run some more camber for track so Ill get them to check everything under the car check the balance check the wheels check the driveshafts and get a new alignment.

This might make me sound stupid but I think the steering wheel might have been shaking a little on the way home or I could feel a shake through the steering wheel if that make sense. It was really weird but I could only feel it for a little while? Also whatever is causing this must be on the passenger side of the car as I had a fire extinguisher fitted on the floor bolted to the front of the passenger seat and it never used to rattle when all was smooth but again after the alignment now it rattles and it does my head in on mountain runs and country drives etc.

[speed freak]

tire pressures are set to 36 psi cold as these are the factory 16" wheels. To me this doesn't seem too high or low for the wheel/tire size but should I try a lower pressure? If they have too much pressure maybe on certain angles on the road they get 'un-balanced' and get a wobble or shake as the tire fights to stay in contact with the road? Bumps can set the vibration/shake off with the car. I have no idea though Im just throwing ideas out there.

[JBT]

Drop the pressures to 28 and see if it changes anything. You can always pump them up again. I just don't understand why people want to run such high pressures in MX-5s for normal (non track) use.

[Magpie]

Speed Freak when I am home next I will make some time to do some tyre temps to get your pressures right, it will just take a few runs at 110 on the freeway for about 10 mins to get the tyres warmed up.

[speed freak]

Drop the pressures to 28 and see if it changes anything. You can always pump them up again. I just don't understand why people want to run such high pressures in MX-5s for normal (non track) use.

Ill try that this week when I get a chance, like you said I can always pump them up again. Im just going off the wheel and tire size and this size you would normally run around 36 or even higher but maybe its not needed in an mx5. Jason at mx5 plus said to run 36 too.

Speed Freak when I am home next I will make some time to do some tyre temps to get your pressures right, it will just take a few runs at 110 on the freeway for about 10 mins to get the tyres warmed up.

Thanks Mark I appreciate that.

Also to everyone that has posted suggestion and helped out some way thanks heaps I do really appreciate it I just need to find some time to try a few more of them and hopefully knock this problem on the head for good.

[manga_blue]

I flatspotted the fronts at Winton once and didn't realise that I'd done it. After that I'd keep getting all these strange little rumblings that only seemed to come up at certain speeds, on certain surfaces and at certain temps. Mania had the car for a week and couldn't find anything. We replaced all the wheel bearings and checked every CV/uni joint.

Finally I coasted it down the main street of Orange with the engine off. The main street of Orange had just been done with fresh hotmix and it was billiard smooth with a slope just good enough to let you pick up speed. At around 15kmh I began to feel every slight bump from the flat spots. Turned out I had 2 medium ones on one tyre and 3 or 4 smaller ones on the other. What was happening was that every now and then they'd get in some sort of sync and beat out a tattoo.

You've got the same signs, but mine is an NA with no ABS. Yours is an NB8B and that should never happen if the ABS is working properly.

Anyway, have you tried a micro-examination of tread depths? Flat spots usually crop up near the inside shoulders of the fronts because the suspension is under heavy load with the wheels splayed out when the tyres let go. Occasionally you'll get a small wear patch on the outside shoulder of a rear if you locked a little while trail braking. The best way is to take each wheel off and roll it along very slowly in the sunlight.

[speed freak]

Ill do that, thanks for your post. Ill have a good look at the tyres this weekend, will remove all 4 again and have a really good look. I have done one track day since the coilovers were fitted but I don't think the issue is any worse then it was prior to this. I have never locked a wheel and never pulled the handbrake while driving so I doubt a flatspot could be it unless a small bulge or flatspot formed over time with hard cornering?

I think you have got it right though, it seems like the car only picks up the vibration/shake at certain speeds. 60 km/h its pretty much always there, at 70 km/h not so much probably why I didn't feel much yesterday only in the 60 zones. Then it must be around 80 km/h it comes back as on my mountain drives the limit is 80 and I almost always feel it vibrate, I mean the roads aren't brilliant but its more then just poor road surface. Highway speeds sometimes you feel it sometimes you don't.

Anyway I lowered tyre pressures to 30 psi hot on the way home today which should be about 28 psi cold. Went to do it this morning but someone beat me to the pump so couldn't stick around or Id be late for work, then went to do it at the servo across from work this arvo but a fuel tanker was parked in the way so I left. Ill check them again on my weekend when they are cold though.

[speed freak]

When my car was in getting its new wheel alignment done on Friday I told them about the vibration and I got them to check over the car. He checked driveshafts and the tailshaft (visually and moved them etc), all bushes, tyres, wheels, hubs, plus probably more I cant think right now haha.

He said everything looked and felt in good condition apart from the wheels. Apparently all the wheels aren't that great but only one was out of round, the passenger side rear. Which was the passenger side front before I swapped them around. So its possible and looking like the wheels might be the culprit.

Still haven't been successful on my 2 attempts at trying a different set of wheels. Either had tyres that wouldn't inflate (completely flat on nb8b wheels) or the wheels very slightly touched the brakes (15" wheels over nb8b brakes).
Might just have to save my pennies and buy my self a set of 16" RPF1's for Christmas ;)

[project.r.racing]

swap you spare for the dodgy wheel and trial?

pretty safe bet that is suspension place found 1 dodgy wheel and no suspension faults. then that is you issue.

[speed freak]

swap you spare for the dodgy wheel and trial?

pretty safe bet that is suspension place found 1 dodgy wheel and no suspension faults. then that is you issue.

???

Are you saying its odd they say its one dodgy wheel and didn't find any faults with the suspension?

I will try the spare, but not too sure how that will go, when the other owner had the car the boot must have got wet as half of the spare wheel is rusted and its left rust marks on the boot floor. See how it goes though.

Its had coilovers fitted recently so that rules out shocks/springs. Bushes looked ok and with tail shaft and driveshafts he only visually checked them, didn't remove and inspect but found issues with the wheels.

[the pirate]

Hey Speed Freak, time for my "Two bob's" worth. This is from "Lateral Thinkers Anonymous". Get your rear discs checked for warpage and get them machined. It COULD be the problem. The vibration could come from the pads rubbing on either or both discs until they "knock off" then don't vibrate anymore. If the vibe is still there then service the rear calipers. Good luck.
Alan.

[speed freak]

Hey Speed Freak, time for my "Two bob's" worth. This is from "Lateral Thinkers Anonymous". Get your rear discs checked for warpage and get them machined. It COULD be the problem. The vibration could come from the pads rubbing on either or both discs until they "knock off" then don't vibrate anymore. If the vibe is still there then service the rear calipers. Good luck.
Alan.

Thanks mate.

I had thought of the rotors as Iv warped brake discs before on the track haha

Iv had all rotors and pads replaced when I bought it but when I got the coilovers fitted that next week the vibration went away, then got a new alignment done then went to the track the next day then it returned. I had another track day yesterday and driving home from work today it was barely there at all so Ill see how it goes but Ill still try out the spare wheel where the bad wheel is.

[zero00]

I can't see that it is one of the wheels SF, you moved the rears to the front and vice versa a few weeks up here in my drive

Totally left field I'm getting the feeling it's the tailshaft slightly, just slightly out of balance. There are businesses that do tailshaft balancing. If the car had been dríven over a small gutter and scraped the TS this could have created a small problem

Food for thought

[JBT]

Zero00, I think it would be a bit hard to scrape the tail shaft given that it is surrounded by the PPF.



I'm putting all my bets on it being wheels and/or tyres. I've seen a car (same model MX-5) with the drive shafts replaced and it still did this. Things in common with SF's car were RE002 tyres and the standard 16" wheels. As I recall, all the tyres on that other car I saw were slightly out of round.

[zero00]

Oh dear! I never let mine run over me to see under there!

OK, I'm going back to my knitted tyre warmers and tuck her back into bed in the garage!

Thanks JBT