Still shaking after alignment
 

I had the car aligned yesterday after I moved the 7” fuchs (with 225/50) from the rear to front and put the new (to me) 8” fuchs (with 245/45) on the rear. I also had turbo tie rods installed at the same time. Question, the car still shakes, albeit slightly, but enough to be annoying. It seems to only shake at certain speeds and for the money I paid I don’t want any shaking. Is this “normal”? Does the installation of the turbo tie rods translate more “movement” into the steering some way? Not possible right? It’s for stability (cornering) not steering correct?

The car ran VERY smooth beforehand and is somewhat un-enjoyable at this time. I will be calling later today to take the car back but wanted to see if anyone had any ideas/thoughts before I do. Note, I used a Porsche shop and not a general alignment shop. TIA. SmileWavy


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Wayne C.
83 SC

did you have the the rim's balanced? Where can you feel the shaking? through the wheel or your seat?

Luke, the shop said they would balance the rims...I did not specifcally ask afterwards :rolleyes: , dumb, I know.

The shaking is coming through the wheel. Can a out-of-balanced rear wheel cause the problem?

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Wayne C.
83 SC

Are the tires still new or in new condition? Maybe your rear alignment was set different from the front i.e. camber therefore yoru tires are not worn evenly.

Examine the current wear on the tires and then re-balance everything. Unless you have some existing wear that has been caused by a past out-of-balance situation this will probably clear it up.

Flat spot on the used tires you moved to the front. Probably not enough to feel when they were on the rear but the front is more sensitive.

Best,
Grady

.....or a broken/slipped radial belt. This has happened to me a couple of times.

I've been finding that switching rear / front tires usually introduces problems. Tires develop characteristics for the particular corner they're on. When "rotating" these idiosyncrasies can work against the charateristics of the new location.

I hate to say it but check for a bent rim. Jack up the car and spin the wheel with a pointer right next to the rim. If there is runout that'll do it. Ask me how I know this.

Alex

if its only at certain speeds then its more than likely a wheel/balance/tyres issue.

how are your wheel bearings? ball joints?

Had a friend with a 944 that had shaking even after several balance jobs. Turned out that the tire was slightly out of round. Took new tires to solve the problem. Can still balance, but shakes because it is somewhat oval rather than round. Suggest you take it to a "good" tire/alignment shop. Not one of the chain tire stores.

Wow...thanks for all the suggestions. I'll check the ones that I can before taking it back to the shop. Maybe I will put the 205/50s (6" fuchs) back on and see what happens since the problem did not exists when I had them on...gonna be upset if it's a bent rim :( . Thanks again.

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Wayne C.
83 SC

Do you have wheel locks on the wheels? if so are they steel or alloy? If not nevermind. I used to have steel ones on my fuchs when I bought the car. If I did not put them in the exact same spot each time it get the shakes. Since I whent to just alloy lugs, never a problem again. Just a thought.

yep, out of balance, probably, possible causes are numerous, most likely tires, wheels, lugnuts... probably in that order

FWIW, alignment can't cause vibration. To vibrate, something has to be loose, out of balance, or out of round.

An extreme toe in or toe out can indeed cause shaking as the tires hop or squirm sideways as they roll foreward. I doubt this is the case here though. If the tire /wheel assembly is running true ie runout at the tread barely perceptable then I would seek out a tire shop with a road force balancer This type equipment can match a heavy spot in a tire opposite a heavy spot on a wheel. I have seen this type balancer work wonders on a car that had a slight shake and a particularily sensitive driver(Me)

also, make sure there's no debris between the rotor hat and the rim. could be a bit of crap there and isn't allowing the rim to seat nice and flat to the hub. maybe take a stainless steel brush and run it over the surfaces of the hub and the rim.

Wayne,

Hopefully it's just out of balance, when the 7's I bought were sent to Al Reed for polishing he said one was out just a tick, I told him they were for the rear and he said not to worry. Did you ever have the 7's checked before you installed on the front for trueness ?

Are you going to Cal Festival of speed Sat. ? I was thinking of leaving around 6-6:30 from here, I got the go ahead tonight to go.

I just checked the description of the work completed...no wheel balance, hopefully that is the problem.

Also, below are the results of the setup:

Front Left Front Right
Camber -0.3 -1.1
Caster 5.2 5.6
Toe .14 .13

Front Cross Camber 0.7
Front Cross Caster -0.4
Total Toe .26

Not sure what it all means (well, I kinda do) but assume it's ok.

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Wayne C.
83 SC

Yikes, I would want that front caster to be more the same, closer to -1 on both sides, not -.3 and -1.1. They can do better than that, and if they can't then go someplace else.

And the total toe seems pretty high too. You have 1/4", but 1/8", 1/16", or even 1/32" is often recommended.

Also, what are the numbers in the rear like? Caster and Camber should be close to equal left to right. Think about the car visually, if the tires on one side of the car were leaning in at the top, but the tires on the other side of the car were straight up or leaning out at the top do you think you would get optimal grip in left and right hand corners?

Rick, no I did not check the 7s...they said they would, I am taking the car back today and will have them check it. I think I am going Cal Festival of Speed, would like to, wife says ok, I'll PM.

masraum, thanks for the feedback, I'll talk to them about that.

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Wayne C.
83 SC

The camber should be close to the same side to side .I prefer something like neg.3/4 deg.. The caster should be up about 6 deg.pos . The toe in if measured in inches is excessive and should be closer to zero (1/16 " toe in) The stagger setup is often used to compensate for the normal crown of a road. More camber ,less caster side to side .I prefer to set up more equally for predictable handling on all roads and live with a slight drift down the crown of a crowned road. If you do indeed have 1/4" toe that can cause slight shaking on it,s own but the readings you posted may be in degrees. Talk to the alignment tech for an explanation.

Thought I would provide a follow-up to my small problem. After two weeks of driving the car I could not take the shaking any longer. I removed the front tires and took them to Discount Tires to have them check the balance...ended up they were WAY out of balance (even though the p-shop said they balanced them). Turns out when the p-shop balanced the tires they left the old weights on them and just added new weights as needed...a HUGE no-no. Got the tires, put them on...now the car drives smooth as butter...it's like I have new car.

Moral of my story...let tire guys work on tires...not general mechanics.

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Wayne C.
83 SC

Glad to hear problem solved Wayne, I've had Discount do all my cars and trucks for the last 10 years with no problems.

Glad you got it solved - it definately is not normal or something that you should live with.

Although I remember in the 80s, BMWs had a problem with shimmy at certain speeds (usually right around 50 mphs). The dealers would try to say it was normal "road feel!"

When diagnosing, perform the most obvious first. You were on the right track regarding installing the old 6" Fuchs to see if the new wheels/tires were the problem.

Does the Pcar shop have their own dynamic balancing machine or did they sublet this out (usually the case)? Even with old weights in place, the "tech" guy on the balancer could have added enough opposing weight to balance the tire. If they sent it out to their balance shop, maybe they overlooked balancing this one tire. OTOH, you said balancing wasn't on the repair order. Not sure what to make of this.

I agree. The L/R front camber is not close enough. LF and RF camber should be the same. If that's the max. adjustment, they should have told you something was amiss. Maybe a bent strut (didn't mean to alarm you) or they forgot to adjust one side... the same side as the out-of-balance tire. If so, sounds like the shop is a little loosey-goosey with details.

Sherwood