I've owned three 914's over the last 25 years and all have had the same issue. At some speed between 60 and 70 mph I get the kind of shake you'd get from an unbalanced wheel. Even after having the wheels balanced I always get it and I've had every kind of wheel and tire combination (steel and alloy wheels of every kind, Yoko's, Bridgestones, Michelins, and Vredestein tires, you name it.) I've talked to a few other owners and they report a similar thing.

Is it possible there's an unbalanced half shaft causing the problem or some other thing like an out of round wheel I haven't discovered? Why can't I get the tires to act balanced?

The easy fix so far is to either drive lots faster or lots slower but I'd rather not have the problem.

I've also had the alignment checked and at least on my current car all's well except the right wheel camber (or maybe they said caster). They can't get it into spec. The shock mount looks like it's all the way forward and maybe that's part of that problem.

ideas?

Same tires on all of the cars ? Bent rims ? Suspension problems ? Is it a front end shake ? Is it violent or just a little ? Is there any consistant with what and when it startes ? Other than the realitive speed ?

I have noticed the same thing in both of my cars in the past, but not in any of the other cars that I have driven that were not mine.

I've had this problem too. One thing I did in the past is to have the wheels/tires balanced on the car. But thats time consuming and the places I found did it by trial and error. If they got it right, wow, smooth as silk.

I bought mich mxv4 for one of 914's recently and now that one is vibration free, so I'm surprised to hear of your bad experience with them. But if you park your car for weeks or months ar a time that can lead to flat spots. Also might want to jack up your front end and spin the wheels to see if the tires are out of round, and check for play in the bearings and suspension. good luck, I know it is annoying. It seems like the 914 is susceptable to this, but its not normal and can be fixed.

I had the same thing and it was the tightness of the hub nut. Not quite tight enough.

A few years back when I had my first 914 I experienced a vibration also.
Here's a thread from a few years back exlpaning what I did to make the drive smooth at all speeds.

Smooooooth Ride

.....b

Hmm, never thought of the hub nut. I'll have to check that.

And yes, it's any kind of wheel or brand of tire I've owned.

It seems to be mostly on the rear wheels even after they've been rotated. The steering wheel doesn't shake but the whole car gets the shakes once it starts to shudder. I hate that kind of ride.

the rubber portions on the stock tie rods going bad? might as well upgrade to turbo tie rods. Just a guess.

first, what kind of wheel do you have.
the aftermarket wheels, rivieras,etc... have not been machined with the center hole perfect.

This leads to a wheel that can be balanced on todays machines (they use the center hole) and it will appear balanced..nope.

I went through this with a superbeetle...these cars are the most sensitive cars to tire balance I have ever seen.

Find a place that has the correct adapter to put you wheels on the machine on a four lug adapter...this way the wheels are balanced on the lugs, versus the hub.

this is the right way...I found the only store around here that has one...it took alot of phone calls...

Rich

I have the same problem of unbalanced wheels even after having the wheels balanced. On my 71 I found the issue to be the lack of a centering ring on the hubs. The wheel could be tightened down in any number of positions that are not exactly in the direct center of the hub.

I ended up getting a pointer (basically a pencil in a portable vice) and for each wheel, spinning the wheel to see if the wheel is centered on the hub. If not centered, loosen the lugs, re-center and repeat until perfectly centered.

The wheels that I refer to which are so difficult to get perfectly centered on my 71, give me no problems on my 74 with front hubs with centering rings.

Spoke

One thing that really helps with non-hubcentric wheels is to torque down the lugs with the wheels -off- the ground. Then you're centering the wheels on the lugs, where they -should- be centered. Not to say that they always are, or that this always works, but I've found it to be quite helpfull...

-Josh2

Years ago, there was a guy that I got to know from auto-x that managed/ran a very respected tire store in the area. Since he ran a Tiger, and I, a 914/4, we were hardly in the same class ! He maintained, and after experiencing the difference, I had to agree, that balancing the wheels after the tires had been mounted on the rims and AFTER the set was installed on the car, was critical. After his shop finished high speed balancing the tires on the 914, the high end smoothness and stability were much improved. It was kinda scary, though, watching f & r tires spinning at high RPM as the car sat motionless.

Unfortunately, that tire service regiment has subsequently elluded me, and I sometimes find myself at somewhere between 60-80, and depending on the road surface, with some annoying steering wheel vibration.

I have the OEM wheels (Mahles) on the current car and they were rotated recently and rebalanced. But no matter what, the rear tires always seem to have the annoying shudder at speeds between 60 and 70. below that it's nice and smooth and above that and it's really pure fun. It did this even before the recent rotate/balance.

I still need to check the hub centricity, though, in case that's mounted incorrectly. I thought of an out of round tire but that would make the shudder travel with the mounting location and that's not what I experience.

Oops, wrong, they're Fuchs.

Very interesting reading.. I'm having the same problem John is having and now I have several things to check. And here I was just going to go the an alignment and balance.

Thanks you guys!

Doug

hmm.. there is extensive stuff on this at miata.net, if you want to bastardize yourself to actually go to that site

But basically, clean out your wheels (make sure there's no dirt in there) get 'em rebalanced, and if that doesn't work, have your tires heat-cycled (cause they could be oval instead of circular.)

If all that doesn't work, maybe look into how true your wheels are...

good luck!

I've found my 914 to be very sensitive to front wheel balancing. Doesn't seem sensitive at all to the rear balancing.

For the front wheels, I've found it helpful to experiment with the position that the wheel is bolted on to with respect to the hub. Paint a mark on your front rotor by one of the studs, and mount the wheel so that the valve stem is lined up with that same stud. Drive the car - if you get the vibration, then remove the passenger side wheel and reinstall it in a different position (make a note of the position). Drive the car again and note if it is better or worse. Now change the position of the drivers side wheel. Keep rotating them around until the vibration is gone, and make a note of how the wheels are mounted so that you can remount them in the same position every time.

This has worked for me.

And like Josh said, tighten the wheels as much as possible off the ground. Rears can be torqued off the ground. Front's can't, but get them as tight as possible, and then torque them after you have lowered the car gingerly.

Demick