I've had a problem for a while where, between about 65 and 80 the car has a pretty severe wobble. The steering wheel will shake pretty bad and is almost enough to rattle your teeth on a long drive.

I took the car in to NTB to have it aligned and the wheels balanced, and it didn't do a thing to help.

Knowing that most places don't know beans about most older cars, let alone the 914, I checked the before and after numbers on the TOE, CASTER and CAMBER against my trusty Haynes manual. Since the numbers NTB gave me look like they are in fractional degrees and the numbers in the Haynes Manual seem to be in Minutes, I don't necessarily know if what they did was "in bounds".

The guy did tell me that one of the rear "trailing arm?" bushings was bad and needed replaced. Could that cause the wobble.

Here is what they are...

BEFORE

CAMBER: LF -0.5° RF -0.3° LR -0.9° RR -1.2°
CASTER: LF 5.4° RF 5.8°
TOE: LF -0.23° RF -0.15° LR 0.08° RR -0.23°
TOTAL TOE: Front -0.37° Rear -0.16°
STEER AHEAD: -0.04°
THRUST ANGLE: 0.16°

AFTER

CAMBER: LF -0.3° RF -0.2° LR -0.6° RR -0.7°
CASTER: LF 5.4° RF 5.8°
TOE: LF -0.17° RF -0.12° LR 0.18° RR -0.23°
TOTAL TOE: Front -0.29° Rear -0.05°
STEER AHEAD: -0.02°
THRUST ANGLE: 0.20°


HAYNES MANUAL

FRONT
Toe: +20' ±10' at kerb weight
Camber: 0 ± 20'
Max Camber diff Side to side: 20'
Castor Angle : 6° ± 30'

REAR
Toe: 0° ± 15' (each wheel)
Camber: -30' ± 20'
Max Camber diff Side to side: 20'


If all this looks good, then I don't know what to do next... I'm stumped.

Doug

Check for out of balance tires or out of round wheels. I would bet you find it there.

Also check your steering bushing in the column, they wear out and get sloppy too.

Get your wheels Lug centric balanced.

Was this going on before your off-road adventure?

how are your tie rods and ball joints?

What is the condition of your wheel bearings?

I have the same problem at right around 60/70 and it comes & goes. I have double checked everything, maybe some day it will just fix it self.

Reason I ask is that my Super Beetle had that, turned out to be worn tie rod ends. I am of the belief that you should replace all that stuff at the same time

I have been fighting the exact same thing for the past week. I did find the front wheel bearing with too much play and took care of that . This helped alot. I have Bilstein front coil overs and installed the Torington bearings between the spring and the pearch. Since then I have had this steeing wheel shake. I'm beginning to wondoer if with the coil overs and no bearing if that was like a built in stabilizer with the coil wrap up created without the bearings. Next step I'm going to have the front tires balanced on the car.

Yes!

same thing on my wheels--they arent hub centric, most of them (including my Riveras--apparently a poor choice in wheels, but they look nice) arent hub centric.

Yeah, this is a long standing problem. Fortunately (or maybe unfortunately) it doesn't seem that "Trail Testing" my 914 changed the wobble at all.

Thanks to all of you for the ideas... I'll have to get some help giving the car the once over for all of these things. I'm not sure how to attack some of them.

I've heard the one about "lug centric balance" before, but when I talked to others who were far more 914 literate than I, they seemed to think that this completely depends on the wheels you have, and some said it didn't matter at all.

Doug -

Based on what Clay and I saw with the suspension console on the passenger side,
you will continue to have problems of some sort until the console is replaced...
Just my .02....

Best -
Thom

Doug: You know that it will "smooth out" at over 90mph..........there's your answer!

Check your wheels for the balance weights. Get the ones with the least amount of weight in the front. I think I heard anything more than 4-6 OZ of weight is an indicator of a bent rim. Again, the ones with the most weights on the rear.

I LOVE this place.

I read the WHOLE question, and it seem pretty obvious that the wheels are balanced, the toe is ok...so...LOOK ABOVE and take a guess what it MIGHT be...

Please, jack up the car and get the rear passenger wheel off the ground.
Put a jack stand under the engine mount bar on the passenger side rear to hold the wheel up in the air, yet the suspension is free and unloaded.

Now, grab the tire...wiggle it.
If it wiggles AT ALL you need to look and see why its wiggling.
these cars have had the rear suspension console rip right off the car, rust out, bushings get worn etc...
It will vibrate at high speed, and then, with all the vibration...break off while you are driving 75mph...
Check both sides of the car, in the rear.

Please look at the part the tire shop told you to look at...it was good advise.

Rich

Yep- Rich is wild-ass speculatin'.

The "bad rear suspension bushing" is whats got ya. Look carefully at the trailing arm "ear" and above it- especially on the inside under the cooling tin- I bet there is separation of some kind.

Wouldn't a bad rear suspension bushing cause your ass to shake instead of the steering wheel? Seems like there might be two problems here.

Don't know if this will help or not. But my 'regular" mechanic balanced out a wheel I knew was slightly bent (side to side run out) on my in-laws' Explorer. He took the tire off, spin balanced the wheel only, reinstalled the tire again and rebalanced it. It only took like 3 oz to re-balance it where before it took like 8+ oz. It also rides alot nicer now.

I agree with several opinions here.

A vibration in the rear can indeed cause the steering wheel to shake (these are little cars).

Lug centric wheels that are balanced hub centrically may not be balanced when centered on the lugs. (get them lug centrically balanced).

Loose or worn suspension points can allow vibrations. (rear bushings, front bushings, tie rods, ball joints, wheel bearings)

Ok! Then why can I go for up two miles or better before the shaking comes back? If I change my speed I can see it come and go! Starts at around 65 mph and i can make it go away at around 70/75. I am all over the map on this. I have had EVERY THING checked out. At 60 mph I am good all day!

I'm guessing that it is a resonant frequency. It could be axle shafts or anything rotational as well.

Is it definitely speed and not RPM related? If so, it is something that rotates that is out of balance.

There is no MAGIC.

If it is there, it can be found. You just haven't discovered the source yet.

what kind of tires do you have? How old are they?
Some possible causes might include a seperated belt inside one of your tires...sometimes caused by fatigue, impact, overload/underinflation or manufacturers defect (it happens to the best of them)...

Also one or more of your wheels might be "oor" (out of round) this happens too....and can be balanced out on a balancer...but it's still oor (you can balance a square)and will vibrate.

Balancers also have degrees (settings for) accuracy. most shops are not too detail oriented and rely on tire technology to make up the shortfall...hence the difference between a top line tire (Michelin/Bridgestone) and lesser products. Kumho, Falkin, Hankook etc...

vibration means anomoly in the rotating mass or attaching structure...bushings, bearings, worn suspension/steering parts, cracked or broken mounts, worn shocks are all good places to look as well as the afformentioned wheel/tire assembly.

Try swap wheels with another teener and see if the problem goes away...if so replace wheels one at a time. If not look elsewhere...

bottom line, if it's still there you haven't looked everywhere. I do this every day with 18 wheel trucks/trailers...it's sometimes teadous and frustrating, but, it's not rocket science (scince I can do it).

Since it only occurs at a specific speed, I'm convinced that it is balance in a rotating mass. And not in the suspension or tie-rods.

I have experienced a wheel shake problem that is speed specific and it has always been solved by balancing or re-balancing the wheels. Glued on weights can fall off. But they are the only way to achieve good balance, and the weights sometimes need to be on both the inside and the outside of the wheel to achieve good balance. Even a flat spotted tire can cause an unbelievable amount of vibration.

So, if not the wheels then check the brake rotors (one with a chunk out of it?), or it is a wheel bearing that is loose. I would check the front bearings for looseness first. We had a rear wheel bearing that had eaten up the outer surface of the outer hub and it only shook when the brakes were applied, and then it shook very violently.

I really think it is a wheel/tire.

Thanks again everyone for the things to check. Now I just need to get someone that is more mechanically minded than I to help troubleshoot these issues.

CLAY????

Hi,
So, have the rear suspension checked.

If you have Porsche wheels, that is fuchs, mahle, pedrinis, or stock steel wheels, balancing should be ok.
I have tried fuchs and steel PORSCHE wheels and they can be balanced from the hub, and work fine. They engineered the wheel truely centered on the hub, and the lugs.

The riviera's are only centered on the lugs, and I found a few that show 1/2 inch out of round when balanced on the center hub.

I think if the wheels are stock, you should be ok, and the problem is in your suspension and alignment.

Doug,
I had the same vibration, and I completely rebuilt the front end.
I still had the vibration.
I jacked up the rear for a different reason, and I bumped into the tire...it wiggled..
I had an ovaled out hole in the suspension console, a simple fix really...

Please look closely at the entire suspension...if you do it soon, the NTB alignment can be redone for no cost.

Rich

I have to echo on the wieghts thing. I tell the tech to make sure he sets the machine to account for both sides of the wheel. or better said, I want lead on the inside and outside of the wheel. this is after I explain lug centric to them and point to the pin adapter on the side of the machine. 75% of the time I get this stupid look from the guy and the comment them wieghts ain't goona look good on the outside.
So what!!!! it won't shake all over no matter how fast I go. That's about the time they ask what kinda car is this for?

Either you do what I ask or I'll go somwhere else.

I was smart and paid a little extra to get a 6 month balance and alignment guarantee. I can take it back in any time in the next 6 months and get it re-aligned and balanced.

Doug

I had similar symptoms, mine turned out to be one bent Fuchs wheel.

Guys...

Doug's car has a tinworm infestation in the outboard side of the Right rear suspension console. I suspect that the alignment is changing, or something is moving around in there, causing the vibration.

Doug...

Your car is in line to be looked at, after I finish my transmission rebuild and reinstall.......