Vibration turning left, not right
 

1999 Boxster. Just replaced the engine from EBay. Never would have guessed but it’s running great. Now that it can be driven there is a heavy vibration when turning the wheel left but smooth as butter turning right.

To put a finer point on it:
I believe this is a vibration from the front end. So I replaced all 4 tires, both front wheel bearings, upper and lower tie rods, coffins support and fork.

The vibration did not go away!

The only thing left I could change is the actual hydraulic steering mechanism and the anti-roll bush’s. And have brakes resurfaced in case they are warped.
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So what is the vibration?
No vibration sitting still regardless of RPM.
Some vibration when going slow.
Going straight there is minor vibration.
The ever so slightest turn of the wheel right and it all goes smooth as butter.
Turn further left and you can find a point of resonance where everything shakes, even your seat.
Further left and it calms back down but is still present.

I have noticed that the steering wheel is turned a bit to the right to go “straight” but I think that is mostly due to my crude install of the tie rods.

——
So here is my plan:
1. Front brake rotors are getting reconditioned tomorrow (Friday) though I think they look almost new. Did seem to drag a little through part of a rotation.
2. I am going to loosen all the suspension parts I installed and re tighten them under load (did not do it previously. Tightened them in the lift. And bc I replaced the engine the super long rear forks were removed too)
3. Then I’m going to get the alignment done

Then I will pray and go for a test drive….

After that I’m not sure what else to troubleshoot or try and in what order.

Could it be the back end transmission motor mounts? (Front motor mount is new)

Could it be something else?

All suggestions welcome!

Erik
1999 Boxster Base
67k mi chassis
101k on the engine
Texas

Since you have vibration on the front axle while turning left, I would bet on the right side wheel bearing..

You can check the bearings by raising the front wheels off the floor and rotate the wheel by hand and also checking for play between 6 and 12 and also between 3 and 9.

PS: If the vibration is on the rear axle, then check the same way. Please note that a bad bearing also 'rumbles' when you load it, and you can also check it going downhill with the engine off, veering to the right, then to the left, a bad bearing you will hear it rumble

Great suggestion. Rolling downhill and engine off. That should rule out engine mounts!

I started by replacing front wheel bearings then everything up front except for the shocks. So that is why I’m starting to suspect the back end.

!!! Update!!!

Rolling downhill and engine off. No vibration when turning.
Rolling downhill with engine idling. Little bit of Vibration.

When I raise the RPMs I get vibration when turning left.


So at this point I’m now thinking something is either loose (a bolt) or the transmission mounts need to be replaced.

I’m going to re check torques for all of the bolts between transmission and motor first.
Then check the mounting bolts.

Bummed I spent a lot of time getting to this point but that advice was amazingly useful.

Thank you @Gilles!

Good candidate is also engine mount. If (when) that is done, ethe engine-transmisson setup moves fairly well in the car..

So here is another update:
- changed our transmission mounts
- changed engine mount
- changed the front ball joints and supports
- full alignment completed

Realized that maybe the vibration was actually coming from the back.
- changed out both left and right axels (CV)

The sound seems to be a bit less but unchanged.


So now I’m going to start looking at the power steering pump.
…


The craziest thing is that there is no vibration if I turn off the car and glide at any speed and go straight or steer.


So the vibration is for sure from the engine in some way.

I now think it is either the power steering pump or steering but no way to easily verify….

Do I just replace it to find out?!


Erik

The "craziest" thing is that you just keep throwing money at it... in an effort to "find out".

Or, in the wise alternative, you could pay a pro to diagnose it. With all the parts you've thrown on it I suspect it wouldn't take long for a pro to arrive at a diagnosis.

You do have a car set up for the next 50,000 miles, though.

Good luck? :cheers:

I agree I could hire a pro, but what is the fun in that? I dove into this car head first to learn. And I often learn more from my failure than my success.

I’m here on the forums for mentorship and education. I’m hopeful for some suggestions on root causing this vibration.

And setting up the car for the next 50k mi is absolutely the secondary goal.

When I picked up my 98 I was all over it... replace this/that looking for a fix. That car has instilled in me a greateer sense of patience and, now, when something goes wrong... I'm trying to avoid throwing money at it instead trying to diagnose then fix.

I'm really interested in what is causing your vibration and when next you throw a part on it that stops the vibration I hope you report. Good luck. :cheers:

Solved!!!

Front engine mount was the issue.

Be sure you install in the correct orientation and use the soft rubber stops. I now understand they actually keep the two pieces of the mount from over flexing and rubbing.

I’m happy with everything I replaced chasing this this down because the car is smooth and I sure appreciate it a lot more now!!