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-   -   Front end shake (http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/80374-front-end-shake.html)

John2kx 09-11-2002 04:43 PM

Front end shake
 
I've got a shake that occurs only at 60 miles per hour. Any slower or faster and it goes away. Actually it starts at 58 mph, is at its worse at exactly 60 and stops at 62 mph. I've been 100+ with no shake but will not do that again until this problem is resolved.

Did a search prior to this post and saw where someone experienced a similar problem but his shake never seemed to go away with increase in speed........he also had shake around corners which I do not have. I am using stock length lugs.

I've checked the following:

Front lugs are tight, balance was performed by one of the top shops in my area and weights are still in place (2.0L Fuchs). Ball joints appear tight and wheel bearings have no play. About the only thing I don't have a feel for are the front shocks/inserts. Not sure about their age but have done a front fender squash test. Both feel the same but not sure what normal is supposed to be. The front end goes down and then back up again smoothly with pressure on fender. No extra bounce is noticed during the rebound.

The shake appears to be on the front left (drivers side) but could be on both sides........I can see the drivers fender shake a little when vibration occures.

Any ideas?

mike95125 09-11-2002 06:01 PM

Not sure if your type of wheels are centered on the hub automatically or if ya got to monkey with it, but its worth a check. My wheels dont center and I get a wobble. The hub on my girlfriends car was warped and caused a similar situation as the wheel (seemingly seated correctly) wobbled back and fort when driven due to the hub being irregular.

Zeke 09-11-2002 07:36 PM

Rotate the tires and see if that changes things. Or install the spare on the suspect corner. A lot of times it's the tires as they wear down and take a bad wear pattern that you might not be able to see. Also check run out of tire. You could have an out-of-round rim, tire or both.

Brad Roberts 09-12-2002 12:10 AM

Hey John,

New struts are stripped and heading to the powder coater.

Anyway... check to see if the shock is tight in the strut.

This requires removing the top nut and pulling the dust cover down and off. There will be a large nut looking "thing" that will probably be loose. These hold the shock in the strut. Bilsteins use a different holding device and require a special tool.

Good luck.

B

psu914 09-12-2002 03:08 PM

my 73 has a bad steering wheel shake between 65 and 75, the car doesn't shake just the wheel. If I speed up or slow down it goes away, also goes away in hard turns. if any one can tell me why I would appriciate it.

John2kx 09-12-2002 03:21 PM

Pulled the drivers side strut apart just a few minutes ago and checked the "nut looking thing" you mentioned Brad. It was tight but I gave it just a little more to ensure it was socked home. It also looks like the insert is fairly fresh (shaft, nut and threads look like new metal). Insert had about a 3" tall bump stop in place. I did buy the car from a autocrosser and he concentrated his efforts on things that made the car stop and go.

Put everything together and dropped car back down on ground. Pulled in and out at top of tire and "did" hear a clicking sound......one pull, one click. Ball joint looks new as well as tie rod. I have yet to pull the rotor apart to check bearings but can feel no play in rotor or any resistance or abnormal noises when rotating wheel. Since the drivers side appears to be where the source of vibration is coming from, it is the corner I'm concentrating on. I did check for play on the pass. side but can not hear the clicking noise heard on drivers side.

I don't really know a method of checking the ball joint for failure but it appears to look ok.......no play visable when pulling on lower stut assembly......any other checks I can do here?

The PO is very mechanically inclined and everything I've inspected or taken apart on this car looks like it was assembled per the manuals/factory.....no shortcuts have been found anywhere in the car.

A NASCAR buddy I spoke with today bets money it is tire balance and suggested swapping front and rear tires. This will be my next move (on drivers side) short of taking anything else apart unless.

One thing I've failed to mention but some of you already know. This vibration was not present when last driven and powered by a 2.0L engine. I just completed installation of a v8 conversion and do carry additional weight in front of car due to radiator and optima battery moved to this location. The front has also been lowered a good inch or so. This was done by PO. A bump steer kit has also been installed. Again, the lowering and bump steer kit were installed by PO and vibration was not present prior to conversion. 200lb. springs provided by Renegade and Bilstiens have been installed as part of the conversion.

Ideas/suggestions?

philinjax 09-13-2002 07:13 AM

John,
The clicking sound may be a slightly loose axle nut, probably should check it to insure it is within spec.
I think the wheel/tire balace, or out of round, is the likely cause of the vibration.
Good luck at it.
Phil

John2kx 09-13-2002 12:51 PM

Zeke/Phil,

You guys guessed it. It was out of round tires. After checking every component in the front end, rotating all tires, removal and inspection of front stuts, wheel bearings and so forth, the cause was actually the easiest thing to check.

After performing all the above and still have a mild shake at 60 mph (swapping front and rear wheels/tires did reduce amount of vibration), I lifted each tire and spun by hand. The wheels are true but the tires are out of round by a estimated 1/8 to 3/16 of a inch.

A switch to my beater wheels/tires confirmed this to be the cause.

Thanks for all the suggestions. Wish I would have checked the easy stuff first but I look at it as a learning lesson. At least now I know how all this stuff comes apart.

John

Bruce Allert 09-13-2002 01:27 PM

I'm having the same problem. Switched front to rear but shakes worse at different speeds. Mike mentioned the wheels not centering themselves. How can you center the wheels? It looks like that would be a trial & error application.
bruce


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