Vibration after changing motor mounts, drivers side CV axle and Trans fluid change

[ErikG]

Hello all,

The title says it all really, well most of it. I have a 3.0 6spd. Last weekend I changed the motor mounts, the old ones were a little sloppy. I had a CV boot that had been cracked since i bought it so i replaced the whole axle. And then i changed out the transmission oil, and rear diff oil. Both filled with royal purple GL4/5 compatible synthetic oil.

Now i have a vibration that i feel through the car, not so much in the steering wheel. From what i can tell its coming from the drivers side, but i cant tell if its the front or back. It seems to be there mostly when i am coasting and becomes noticeable from 30 up to 80. If i accelerate at all it goes away and if i brake just a tad harder than i normally would, it also goes away. If there is a dip in the road it becomes noticeably worse in all situations; coasting, accelerating or braking. It also feels like it is higher frequency than what a tire issue would be. There are no noises that i can hear associated with the vibration.

Could this have vibration have been there before and now the new motor mounts are transmitting that vib into the car?

My plan is to put the old CV back in temporarily to see if its the axle. I have rechecked the oil levels and all is good there. I have also tried to tweak the motor mounts. When i installed them, i tightened them in with the car in the air and the suspension at full droop. When i reread the tutu, i noticed that i should have had the cars weight on the suspension so i loosened everything and put blocks under the tires and re-tightened. The vib was unchanged.

Any thoughts on the matter?
Thanks in advance,
-Erik

[rocket1420]

Do you have the motor mounts rotated correctly? There is a guide "nub" that must go into one of the slots. Are you also sure you put them in the right hole?

Which brand axle did you install?

[Luxus Panzer]

Also...did you leave the bottom bolts loose on the motor mounts...loosen the snub mount bracket...let it idle..rev it... Then tighten everything. Do this and I bet your vibration goes away.

[VAGlover]

What kind of axle did you replace yours with? It's very common to have vibration from cheap chain store axles. My best recommendation is to learn how to reboot the old axle. It can be hard your first time but gets easier with each attempt.

[shurur9]

I Thought axles are supposed to be replaced in pairs, as most aftermarket axles are solid and OEM are hollow...???

+1 on rebooting or even rebuilding your own.
YouTube

[A4SoftWalker]

There is no advantage to swapping axles in pairs.
I've done it before but only as preventive maintenance.
Last weekend I swapped out an OEM axle with an RAxles replacement.
Our axles are solid not hollow. They won't last long if hollow seeing the force and torque they live through. A sway bar might survive being hollow but those are usually MORE expensive due to more costly materials.

Any company that would take that heavy metal axle of ours and make it hollow without in increase in quality and thus price would go out of business with the failures that are sure to follow.

With regards to the op vibration issue there is some previous issue with using Royal Purple lubricants in our transmissions and differentials. They are considered rather thin.
Anyone using them with success can chime in but I have tried them and I agree with what others have posted on here in the past.

Ive used Royal Purple oil mixed with Amsoil for years in my engine.

[shurur9]

There is no advantage to swapping axles in pairs.
I've done it before but only as preventive maintenance.
Last weekend I swapped out an OEM axle with an RAxles replacement.
Our axles are solid not hollow. They won't last long if hollow seeing the force and torque they live through. A sway bar might survive being hollow but those are usually MORE expensive due to more costly materials.

Any company that would take that heavy metal axle of ours and make it hollow without in increase in quality and thus price would go out of business with the failures that are sure to follow.

With regards to the op vibration issue there is some previous issue with using Royal Purple lubricants in our transmissions and differentials. They are considered rather thin.
Anyone using them with success can chime in but I have tried them and I agree with what others have posted on here in the past.

Ive used Royal Purple oil mixed with Amsoil for years in my engine.

OK well..the OEM axles on the B5 2.7 are hollow and harmonically balanced.
My 3.0 has hollow axles with audi OEM part labels still on them.
Raxles supposedly use OEM shafts..got it in an email.

so... if one axle is solid and one is oem hollow you will lose your harmonic balance.
If you replace in pairs chances are that it might be ok.
I have a link, that I must dig up, where a poster replies that this mismatch or replacing one or both, even, with cheap axles can cause this problem.

Maybe the 1.8 is different.
Dunno.

After researching, for me it would be Raxles or OEM...or save $$$$ learning to rebuild your own with any good used Audi axle off of ebay for the CV parts.
German (Austrian...) bearings and German QC.

youtube is your friend.

OEM boots can be had for "cheap" on ebay or www.autohausaz.com

88888888888888888888888888888888888888888888888888 888888
Aside and a bit of fun: I worked with an Austrian Stanford grad engineer who had friends who were designers at Audi.
He once told me with a gleam in his eyes:

"No..you must understand that the Audi and BMW are not German cars; they are Bavaria Austrian. We only allow the Germans to help us build our cars, because they are useful to us."

[ErikG]

Hey all thanks for the input. I had a busy weekend and wasnt able to check on here. Barely had a chance to swap back axles.

In short it was the cv axle. That is what i get for going with the chain store. I had an opportunity to change the axle and sourced it from the first place i could. Lesson Learned.

@rocket and Luxus, yeah i made sure everything was in the right orientation when installing the mounts. At first i had one that was not in the right orientation and i couldnt get the mount bracket to sit right. The daya after i did the mount and axle change, i was rereading the tutorial for the mounts and found out i had not left them loose, nor did i have the weight of the car on the wheels so i loosened everything revved it and retightened and it was still there..

I will more than likely get a rebuild kit and replace the boots.

@A4Softwalker: Overall i am happy with the royal purple. i will look into fortifying it with the AMS oil. What AMS oil do you use and what is the ratio of RP to AMS?

@ shurur that is an interesting point about the harmonic balancing, and it being possible that by replacing both makes it less likely to have harmonic issues. This vibration felt like a harmonic vibration because it was really bad a 35-45 and then bad again at 65-70 and above.

@All: I will look into the boot replacement this week. Thanks for all the advice. I love this place!

-Erik

[Jwalker000]

I have a similar issue my son's '02 a4 1.8 FWD with Vibration. After replacing both axles with FEQ and 034 motor mounts, snub and Trans mount from ECS all was good for a few 100 miles. Then there was an idle vibration... The idle is smooth on a cold start then after 45 seconds or so when the idle drops a bit (800-820rpm) it will vibrate, rev it to 900+ and it goes away a bit. However, on acceleration... No matter what speed, there's a heavy vibration almost like your driving over very rough road... The mounts and snub are fine and installed properly as noted on the forums. When mashing the gas to get to speed, the car vibrates, I let off the gas to cruising speed and give slight throttle its all good... A little more throttle and it vibrates. I feel it most in the steering but the whole car shudders. It has good power so I don't think it's a misfire. There's no vibration on deceleration. I did get a P0300 , P0303 once last week but that hasn't come back. I ordered genuine coil packs and plugs from ECS just to rule them out. The car has 191.7k on it and it runs great, no oil leaks etc....
At 170k I replaced the Turbo, axles, radiator, complete suspension kit including shocks, complete 034 pcv system, ECS timing belt kit, Changed the trans fluid and external filter all from ECS etc..... The CVT is holding strong, lol... unless.... It's the Trans going out and making the vibrations.. There is a slight whine while driving/accelerating but I think that's normal, right? So, does this sound like the FEQ axles are the culprit? What else should I look into? Oh, there is left to right slop on each side of the axles.. Like 1/8 to 1/4" , it clanks easily by hand.. Sorry for the long wind but I thought i'd give some history on the car.

[shurur9]

I never used my FEQ shafts from ECS.
The range of the outer joints was limited and the shaft bearings kept slipping out of the inner axle cages as I attempted to install/compress them.
That is, the inner joints would not let me compress them as I installed them without the bearings slipping out of the inner joint cage.
Also, The FEQ shafts appeared to be solid.

I never sent them back to ECS; although they graciously offered to take them back several years after I had purchased them.
I just stole the boots from the FEQ shafts to "rebuild," i.e re-grease, my original shafts.
I kept one FEQ shaft as a Hammer to pound out my front wheel bearings; so now it is a tool for me.

I couldn't even remove the outer CV on one of the FEQ shafts at all; it bend my jig that I had bought.
That one went in the trash.

I think you are on the right track in suspecting the FEQ shafts.

You can buy OEM used joints or complete shafts and new boots and clamps on Ebay.
I repacked my joints with green grease. Any synthetic high temperature grease will do.
The Austrians and Germans have been making quality Bearings at least since WW2; I trust that.

Wor$t case there is Raxles....should you have deep enough pockets.

Others who are more knowledgeable about the CVT may have other thoughts....

Please follow up within this thread when you find the solution to your problem.
And thank you for analytically finding this thread to post in.
It is duly noted.

[rocket1420]

I have a similar issue my son's '02 a4 1.8 FWD with Vibration. After replacing both axles with FEQ and 034 motor mounts, snub and Trans mount from ECS all was good for a few 100 miles. Then there was an idle vibration... The idle is smooth on a cold start then after 45 seconds or so when the idle drops a bit (800-820rpm) it will vibrate, rev it to 900+ and it goes away a bit. However, on acceleration... No matter what speed, there's a heavy vibration almost like your driving over very rough road... The mounts and snub are fine and installed properly as noted on the forums. When mashing the gas to get to speed, the car vibrates, I let off the gas to cruising speed and give slight throttle its all good... A little more throttle and it vibrates. I feel it most in the steering but the whole car shudders. It has good power so I don't think it's a misfire. There's no vibration on deceleration. I did get a P0300 , P0303 once last week but that hasn't come back. I ordered genuine coil packs and plugs from ECS just to rule them out. The car has 191.7k on it and it runs great, no oil leaks etc....
At 170k I replaced the Turbo, axles, radiator, complete suspension kit including shocks, complete 034 pcv system, ECS timing belt kit, Changed the trans fluid and external filter all from ECS etc..... The CVT is holding strong, lol... unless.... It's the Trans going out and making the vibrations.. There is a slight whine while driving/accelerating but I think that's normal, right? So, does this sound like the FEQ axles are the culprit? What else should I look into? Oh, there is left to right slop on each side of the axles.. Like 1/8 to 1/4" , it clanks easily by hand.. Sorry for the long wind but I thought i'd give some history on the car.

That last part is obviously tie rod ends. Get them changed ASAP or someone is going to go for a ride when one of them breaks. They are really easy to change on these cars. This could cause your vibration on acceleration because the tie rods are what holds the toe in place. If they can't do that, the alignment changes and things go wonky. Check your front tires as this can cause terrible uneven wear.