Shimmying while accelerating in high gears (AWD Manual) T5

[MadeInJapan]

Background: So, I have a '07 S40 T5 with AWD manual transmission 18 inch OZ wheels. It's been lowered 30cm with Heico coilovers and rear suspension, and the ECU is upgraded with Elevate Tune- stage 1 (other Elevate stuff like intake manifold, BOV, etc). It's been a super fun car!! I'm approaching 80K miles and my second oil change since buying the car from it's 3rd owner...original owner bought it as a service man in Germany- thus the Heico upgrades at the factory there.
Tires on the car are some that are not very common (and not great)... I was hoping to make it to the end of 2017 with this set...
Lots of pot holes and bumps here, even so places on what are otherwise smooth surfaces on the interstate...some I've hit recently (really hard) even though I've tried to avoid them. The car does not like them and the driver's side wheel was cracked this past winter from a bad pot-hole and had to be welded and repaired. After that all was good, the wheel that was re-mounted balanced right up and the car drove smoothly.

Now, this past weekend, I drove about 60 miles down the interstate to go see the solar eclipse and on the way there I started noticing a slight shimmy when I was accelerating in 6th gear (at about 75-80).
As I drove it the next day I thought whatever was going on went away and all was fine (a quirk?)... not so fast. However, over the next few days the shimmy from the front of the car while accelerating has gotten worse...first it was in 6th gear, then in 5th and now even in 4th and 3rd gears, especially when accelerating hard. When I let off the gas at high speeds now and hit the brakes, I feel a slight shimmy in the steering wheel too... if just coasting, all is smooth. I really sense that the issue is from the front right tire area. What went through my head were- an axle baring that is starting to go, power transfer to the rear wheels that isn't working out very smoothly (for some reason), a low tire on that side or an axle shaft that is starting to go. Let me clarify that right after I got the car (at about 70K miles), I had it into my local mechanic who said the CV boot on that front right side was torn and so he re-booted that axle with an actual Volvo boot (not a half-boot)...things were fine and smooth after that for over a year.

Today during my lunch hour I stopped to get gas and when I checked the tire pressure I noticed that the right front tire was at 24 psi while the driver's was at 35... hmm...problem solved? Not so fast... After making sure air was at 36 psi in both front tires, the vibration seems to be more pronounced than ever... This is however as you accelerate and not while coasting or maintaining a speed. Coming home from work was no fun driving this car anymore (you have to accelerate up a hill to get to my house). After pulling into my garage I checked the tires... all looked fine- but the inner part of the tire is hard to see. When I shined a light into the inner portion of the right front tire, I see that there is excessive wear just on the inside edge of that right front tire. I'm thinking at this point that I hit a pot hole rather hard maybe a week or so ago and got the tire out of balance and all of this shimming is the result of that...Or, could it be that indeed an axle is starting to go?

I plan on rotating that tire to the rear tomorrow and see if it makes a difference. I'm probably in for an alignment (just had one a few months ago) and balancing and most likely new tires sooner than I thought.

I know I'm thinking out loud here but if anyone has any insights- if this sounds familiar or whatever, I'd like to hear your thoughts. My experience with Volvo's is that things hardly ever happen in solo and that it's usually more than one problem that occurs simultaneously... but so far with this S40, I have been very fortunate. I've had absolutely no quirky issues like I've had with other Volvo's I've owned.

Thanks for any response to my posting!
-MIJ

[MadeInJapan]

Tires rotated and balanced.
3 issues noted... I had hit something and knocked the car out of alignment...right tire was unbalanced (lost a weight?)...front tires's inner tread was pretty much gone to the point that the tire in question has the band starting to show through.

I need new tires and an alignment. Considering buying 17" factory wheels and getting away from 18's although the OZ wheels look really nice....they just don't handle these TN roads well at all.

[MadeInJapan]

Put on 4 new tires all around... most of the problem is gone but I can still feel a little shimmy... I have learned from reading that lower front control arms are a weak link in our suspension and at 80K miles, it's a surprise they have lasted this long. There is a C30 and S70 (mid-year 2006 change for S40/V50's) OEM sports control arms (heavy duty) that are actually cheaper than the regular lower arms. I have ordered these from Tascaparts.com along with the torque to yield (TTY) rear bolts that must be replaced when you replace the arms. I plan on doing the work myself as soon as I get the parts in and then take the car for an alignment. I would have ordered from FCPEuro (actually my favorite parts place) but they stopped price-matching, although they do guarantee any part for life. Cost savings from Tasca was about $50 for the order I placed this morning.

[MadeInJapan]

Well, I have learned from being under the car that the inner cv boot is oozing on the passenger side. So, this is the source of my vibration. I have also learned that GKN is the OEM maker of our axles. Apparently Autozone has a replacement (Duralast Gold) that they claim is made by GKN. I have put $193 and some change down for this axle to be picked up tomorrow. If it doesn't cut muster then, back to Autozone it goes and I'll be ordering the close to $500 axle from Tascaparts or volvopartscounter.com I have had to order the axle seal and larger carrier ring seal for that particular axle (for MM66 Manual transmission) also to get the job done at a price of close to $50 just for the seals as I don't want to cheap out on aftermarket parts here and possibly have problems later. So all told, I'm out over a grand to fix this vibration that impacts my acceleration. Of course, I needed tires so I'm happy to get them but the other issues, I really could have done without.

[MadeInJapan]

I know no one is responding to this thread but that's okay- maybe it will help someone down the line.
So the Duralast Gold came with a number across the axel on a sticker. When I googled it a Chinese company came up for this axle so this is not a GKN at all. Still, the build looks good. I may put it in anyway and drive around while I get the OEM axle out of my car rebuilt... at least there was no core charge like there is on so many of rebuilt parts. Of course, the Chinese axle may prove to be okay- but people who post about out Volvo axles don't think so. We'll see. I'll have my indy mechanic look at it next week and we'll decide.

[jimmy57]

The front CV joint on rear driveshaft is a very common source for vibes like you describe. The front CV axle might be all of it but if not then drop that shaft and pack the front joint. The proximity to the catalytic converter bakes the grease and it gets gummy. If the CV joint there needs attention you won't be able to move the shaft fore-aft.

[MadeInJapan]

Thanks for the head's up, jimmy57- it's going to my indy mechanic tomorrow or the next (wherever the seals come it)- so I'll mention that to him and I'm sure he'll check it out too. I assumed it was the inner passenger CV because I could see the oozing from that boot. it too is very close the engine and could bake inside when things heated up enough with less grease in it than there should be. But like you said, it could be more than the front axle joint... I would hate to think of the price for repairs on the shaft joint you mention.

[MadeInJapan]

All parts finally got here this weekend. What I ordered on priority were the seals for the front axle which includes a larger one due to the support in the middle of the car. I also have new control arms going in. I'm leaving it at my indy mechanic tomorrow. Sure- I can do the work but I trust him more to do full diagnostics and I'm going to have him look at the prop shaft boot on the front as well. Hopefully that isn't the issue here... In the meantime I changed out rotors and brake pads on my S70 today.

[MadeInJapan]

Took my S40 into my indy mechanic Monday eve for him to get onto it this week and I picked it up yesterday after work.
The good news is, the axle fit and the lower control arms had some play in them - more than they should, especially the right one and so they were changed out.
The front CV on the prop shaft was fine!
No more vibrations!!
Getting an alignment tomorrow.
Will know if I'm in need of the adjustable rear control arms. I'll start a new thread regarding them.
-MIJ

[MadeInJapan]

Yesterday it was the alignment. I was surprised that my rear was in spec and so no need for the adjustable camber arms.
My front however is out (-1.75) pretty even on both sides. There is no adjustment here- you can't use camber bolts as the front struts (in my case- coilovers) fit into a spindle. The only possible solution is a slotted upper camber plate that will allow movement inward and out ward changing the geometry of the front camber by about 1% at the most. There just isn't much room up top. Anyway, was wanting to ask members here if they have done this? If so, were you able to buy such a plate or did you make your own? Right now, the alignment specialist has my front tires set at about 1 degree toe-in to compensate for tire-wear created by the negative camber. This is okay although not ideal. If he had left the toe-in alone, I would get better cornering and control on the front but would also chew through tires on the inside edge.