Questions for the mechanically minded

Wivvix · Postby **Wivvix** » Fri Dec 19, 2008 1:27 am

Time for another update.

Today I left the mx5 with Tim @ West Racing to ascertain what was the cause of vibration.

Apparently the wheel hub face on the rear right corner has .004" runout. The rear left had .001" runout. Tim does not believe it to be the likely cause of vibration.

On the list of suggested "things to check" are removal of half shafts, cv joints serviced/replaced, and right flange straightened or replaced.

Which of these would you guys recommend I look at if any? How much should servicing/replacing CV joints cost? I have been given an estimate of $300 per side (rear) incl labor.

I'm not inclined to think it's CV's, because there's absolutely no noise coming from them, there isn't any clunk when accelerating or decelerating, and the shudder doesn't progressively get worse with speed, it's on from around 50-60kph then off til around 110kph.

Is there someone in Perth who I can take my mx5 to, and really trust to not just take my wallet for a ride? I don't mind travelling, even if it's just for someone who's very experienced with mx5's to come for a spin and see what i'm on about.

Cheers

Postby **mx52nv** » Fri Dec 19, 2008 1:56 am

Wivvix wrote:Is there someone in Perth who I can take my mx5 to, and really trust to not just take my wallet for a ride? I don't mind travelling, even if it's just for someone who's very experienced with mx5's to come for a spin and see what i'm on about.

You just missed our forum gathering mate - any chance of you coming along to the next Sunday club cruise in January?

Wivvix · Postby **Wivvix** » Fri Dec 19, 2008 2:59 pm

mx52nv wrote:
Wivvix wrote:Is there someone in Perth who I can take my mx5 to, and really trust to not just take my wallet for a ride? I don't mind travelling, even if it's just for someone who's very experienced with mx5's to come for a spin and see what i'm on about.

You just missed our forum gathering mate - any chance of you coming along to the next Sunday club cruise in January?

Unfortunately not as I work Sundays.

Postby **mx52nv** » Fri Dec 19, 2008 3:07 pm

What about the next January meet up for the forum guys?
You tell me what day and time in the 3rd week of Jan '09 suits you :mrgreen:

I'll work it into that

Mr Morlock · Postby **Mr Morlock** » Fri Dec 19, 2008 3:27 pm

You did mention that the car has been vibrating from when you bought it. If you fitted replacement wheels and tyres afterwards then I doubt this is the problem. I would have thought driveline engineers might be the best bet. I guess they would look for misalignment of the chassis / driveline perhaps from an accident or excessive wear in driveshaft or half axles. I must confess to not really following the comment about CV joints and was labouring under impression that these are found on front wheel drive cars. Hope you nail it soon.

Wivvix · Postby **Wivvix** » Fri Dec 19, 2008 7:21 pm

mx52nv wrote:What about the next January meet up for the forum guys?
You tell me what day and time in the 3rd week of Jan '09 suits you
I'll work it into that

Monday 12th to Wed 15th I have off work. I can probably make the January meet up with the forum guys, as long as it doesn't run on a Sunday :wink:

Mr Morlock wrote:You did mention that the car has been vibrating from when you bought it. If you fitted replacement wheels and tyres afterwards then I doubt this is the problem. I would have thought driveline engineers might be the best bet. I guess they would look for misalignment of the chassis / driveline perhaps from an accident or excessive wear in driveshaft or half axles. I must confess to not really following the comment about CV joints and was labouring under impression that these are found on front wheel drive cars. Hope you nail it soon.

The thing is, when I looked at the car I wasn't really testing for vibrations throughout all speeds. I was mainly looking for the 60mph shimmy. It only vibrates from around 110kph onwards, and I didn't go that high when I tested it, as it wasn't anywhere near the freeway. I don't recollect there being any vibration between 50-60kph. The problem is, the tyres let go on a corner the day I bought it. Fishtailed 180 and smacked a curb on the rear right corner. Haven't had a vibration free drive since, not in my car anyways! :lol:

Replacing the wheels/tyres ought to have eliminated that as a possibility anyway. I think you're probably on the money with driveline engineers, but i'm hesitant to because I know it'll cost me $200-300 just to get some sort of diagnosis, and then another $300-500+ for work to be done.

From what Tim said, there are two half shafts and four CV joints, two per side. I know very little about CV joints, so I haven't the faintest idea whether this is accurate or not.

Mr Morlock · Postby **Mr Morlock** » Fri Dec 19, 2008 8:49 pm

Wivvix you mentioned smacking the kerb. There might be a connection with that event so a careful check of components ( alignment/ bent wishbone etc) on that side would be something to check. I reckon you will just have to take it to a competent shop. You still have a say on what you are prepared to spend and the good guys will not work on an open cheque basis. Good luck

Wivvix · Postby **Wivvix** » Sun Dec 21, 2008 9:36 pm

A friend and I were discussing this issue the other day. He has a 91 mx5.

Driving with the roof down results in what appears to be a complete absence of vibration.

Could this be due to an overly stiff chassis? I'm somewhat perplexed by this variable. Removing the soft top makes the car less aerodynamic, but improves ride quality?

I'm going to get another opinion tomorrow regarding tyre balance and roundness, and depending on the outcome, I may be getting a re-alignment done by somebody competent (previously done by bob-jane immediately after smacking kerb).

Can anyone recommend some wheel alignment specs? I want it to handle well on normal roads and maybe do a little track, not too worried about the life of the tyres.

Cheers

Alex · Postby **Alex** » Mon Dec 22, 2008 1:19 am

viewtopic.php?f=76&t=15398

Wivvix · Postby **Wivvix** » Tue Dec 23, 2008 2:36 pm

Well today was another somewhat interesting day for the vibration chronicles.

On the advice of my mechanic (does the vast majority of work on my cars), I took the mx5 to an ian diffen tyre centre to get them to check out the tyres and balance.

Balance was perfect, literally, but.... 3 of the tyres are out of round. First checked were the front tyres, and immediately upon discovering the first instance of out-of-roundness they fetched me to show me. Then they discovered both rear tyres were even worse.....

So long story short, looks like it could be tyres after all. Alignment will go ahead as planned with wheels world, and we'll be looking at the tyres closely tomorrow.

Is it true that when tyres are cold they can appear to have flat spots?

Cheers for the link Alex.

Wivvix · Postby **Wivvix** » Wed Dec 24, 2008 6:22 pm

Back from Wheelsworld today. Nothing "interesting" to report unfortunately. Wheels world checked the tyres again and said they were "fine".
Perhaps the tyres had been sitting on cold concrete for too long, and made the tyres appear out of round when they weren't really?

Anyway alignment done. Rear LHS toe was out by quite a lot, and cambers were fixed up. Handles quite a lot better, feels much more neutral on the road.

As far as vibration is concerned, I guess i'm back to committing $$ to get things looked at/serviced/replaced. I think Veem engineering will be the next on the list, get them to pull the driveshaft out and check that all over for me.

tbro · Postby **tbro** » Wed Dec 24, 2008 7:01 pm

You have a pm

Terry

Postby **Okibi** » Sun Jan 04, 2009 5:46 pm

Yup, a different set of tyres would help discount an out of round tyre.

Wivvix · Postby **Wivvix** » Wed Jan 07, 2009 8:22 pm

Ahh. Another week, another chunk of pay out the window, and more time without a car.

I'm beginning to get a hang of this public transport thing. The train is quick, reliable, and only costs $1.40 to go from here to canning vale. Such a shame its so god-awfully boring.

The mx5 went into Veem engineering at 9:30am on Monday 5th January. Within half an hour, the guys had the driveshaft on the bench and were showing me the "culprit" of the vibration. Two universal joints in the driveshaft were apparently "on their way out and partially seized". Glad that they were so adamant it was the cause of vibration, I gave them the thumbs up to replace the driveshaft, because "they were sure". :roll:

Today (wed arvo) I picked up the mx5. Upon arriving at Veem and greeting John, I wasn't met with the jubilation I expected of someone who'd tracked down and defeated, what was fairly well established as the source of much aggrovation..... that's because they hadn't. Apparently the driveshaft and uni's have been replaced. John and I went for a drive, but much to my dismay that god forsaken vibration is still there, its not quite as bad, but ITS MOVED. Now you can even feel it at 60-63km/hr?!? Furthermore, the car feels very different..... i'm not sure if it's a good thing yet.

On Monday i'll be taking the mx5 back so they can have an actual mechanical engineer go for a drive and have a poke around. John was fairly receptive to my anger as we took it for a spin, partially because it'd taken 2 days on top of what he originally said to get the work done, and because they were so adamant it was universal joints, and not half-shafts like i'd suggested. I've not had to pay for anything yet, but inevitably I suppose i'll be handing them my plastic and never see that money again.

I'm getting close to the end of my tether with this car. Soon i'll be looking at cars again, and depending on what's available, pass this mx5 along for someone else to deal with. If anyone knows an engineer/mechanic who is looking for an mx5, this might be right up their alley. :wink:

Tezzax5 · Postby **Tezzax5** » Sat Jan 10, 2009 9:03 am

Get Someone to have a closer look at the wheel bearings.
They need to be pulled out and cleaned and physically inspected

A roller that is starting to collapse can (Catch on the cage). If it is well greased there won't be any noise.
The failure wil only show when it has a load placed on it....eg-: the weight of the car.

I had VW super beetle that i threw a motza of money at but it came back the same shimmie....Till i did the bearings..

Just something else to have a look at...