SwedeSpeed - Volvo Performance Forum banner
1 - 20 of 21 Posts

·
Registered
Joined
·
3,265 Posts
Discussion Starter · #1 · (Edited)
Picked up a 2008 Sport last month and it’s a real joy to drive.

One thing I notice though is a slight “knock” below the floorboard when applying power and when coming to a stop. Kind of slight, only hear and feel it when the drivetrain is loaded or unloaded.

Have gone through all the motor mounts and they look good as do the CV boots on both sides. No issue with end links or suspension, everything below seems solid.

It appears that the “knock” appears to be coming from the driveshaft to angle gear. When I get under the car and rotate the driveline, I get around 10 degrees of rotational play and can hear/feel the driveline contacting something at both ends of the play, towards the front of the car. Pretty sure this is where my ‘knock” is coming from.

Not hearing or feeling anything other than the “knock” and it drives just fine. It may indeed be something not to worry about but I was hoping someone might be able to get up under theirs and let me know if they see anything similar. Specifically driveline play and contact at either end of the play.

On my 2005, I don’t get any real movement of the driveline but everything is different (pretty sure they got rid of the spline when moving to the TF-80 6 speed, don’t see it in the parts breakdown).

Someone check and let me know when time permits?

Thanks
 

·
Registered
Joined
·
1,199 Posts
Hm that's low miles for a failure. But the torque of the v8 does stress components more than the other engines.. Does the output wobble up and down or anything, or its just spinning the 10 degrees straight?
 

·
Registered
Joined
·
3,265 Posts
Discussion Starter · #6 ·
No up/down or side/side, just rotational. And subframe bushings are fine, just checked them and did IPD poly inserts.
 

·
Registered
Joined
·
2,026 Posts
I just don't see how you would "feel" that through the floor. have you checked the heat shield above the front muffler?

wait.. know what? are all of the bolts installed on your belly pan? I had one missing once and it felt like i had a control arm going loose.
 

·
Registered
Joined
·
3,265 Posts
Discussion Starter · #8 ·
All bolts are good, it's the application of power and release of power that causes the "knock". Can't say I feel it per se under the floorboards, it's not abrupt or anything like that. But it's a noticeable sound by me.

Again, if someone has time and can get up under a cooled down car (so ya don't burn your hand reaching up around the exhaust to grab the driveline), I would appreciate it if I could get feedback on the driveline rotational play and whether you can feel anything when you get to the ends of the play.

This is my second XC90 although it's my first TF-80SC/V8. I'm WAY tuned to what my other vehicle does, both "sound and feel". This one does something different.

Thanks
 

·
Registered
Joined
·
3,265 Posts
Discussion Starter · #10 ·
Mine is tight, no movement but it's a 2.5 04 so I don't know if that's helpful.
Not really, but I certainly appreciate the effort. My 2.5 '05 is tight as well.
 

·
Registered
Joined
·
3,265 Posts
Discussion Starter · #11 · (Edited)
Took it to the dealer, driveline play is more or less normal (?).

Problem determined to be axle "ping", tech applied compound to the axle/hub interfaces, put everything back and the "knock" on load and unload is now (pretty much) gone.
 

·
Registered
Joined
·
14 Posts
Any chance you could post a pic of where exactly they applied the compound (which is what, grease?)? Is any disassembly required? I have this same issue on our 07 Sport under the circumstances you described. That little knock drives me crazy. Neither wife nor mechanic even hear it.
 

·
Registered
Joined
·
572 Posts
Any chance you could post a pic of where exactly they applied the compound (which is what, grease?)? Is any disassembly required? I have this same issue on our 07 Sport under the circumstances you described. That little knock drives me crazy. Neither wife nor mechanic even hear it.
It's the front axle splines, where it slides into the front wheel bearings/hubs. We slide them out, apply the adhesive, then just slide the axle back in. Let it set up, & it takes up all the play between the splines. No more noise.
 

·
Registered
Joined
·
672 Posts
I think I might have the same issue. The noise you have described sounds similar. My indy mechanic checked it out, and said the following, "Found the LF axle pops in direction change. Check both front axle bolts and wheel bolts - all tight. Needs axle replacement to correct complain." thebracko - is that enough for you to say this sounds like a similar issue?

I'm certainly interested in giving the compound a go, sounds far more economical than replacing the axle.
 

·
Registered
Joined
·
3,265 Posts
Discussion Starter · #15 ·
To be honest, in my particular case I think the "fix" made things a little less noticeable but I feel the same load and unload "mechanical contact" under the car. It's not a "knock" per se. I took the work in stride (under a Volvo dealer used vehicle warranty) as a goodwill gesture and it seems like it did indeed makes things more quiet.

As a point of information, here's another link on the subject: http://forums.swedespeed.com/showthread.php?137368-Axle-ping-DYI-how-to-redo, a Loctite component is noted but I have also read about using a Teflon pipe compound. Think it's anything that locks, fills, or cushions the space between the splines in the axle and in the hub. Few iterations of SEMS screws that hold the axle in the hub over the years as well so appears as though some thought has been made about the problem (which certainly still persists today).

As a more final note, I never got any answer on the original question of driveline rotational play and the metallic contact at either end. Am still interested in anyone who might be able to check this. I remain inclined to think this is at least still part of my "issue". Thanks
 

·
Registered
Joined
·
572 Posts
I think I might have the same issue. The noise you have described sounds similar. My indy mechanic checked it out, and said the following, "Found the LF axle pops in direction change. Check both front axle bolts and wheel bolts - all tight. Needs axle replacement to correct complain." thebracko - is that enough for you to say this sounds like a similar issue?

I'm certainly interested in giving the compound a go, sounds far more economical than replacing the axle. How do I respectfully ask the mechanic to try this or at minimum explore this? I only deal with the service writer(s) who aren't the most responsive when I lead off with, "So I read this thing on the boards, and...".
Yeah, you certainly don't need a new axle for this. The loctite or Teflon paste should do the trick. Regardless, it's just a noise and is not a safety or reliability concern at all.
 

·
Registered
Joined
·
572 Posts
Cool good to know. Is there a service bulletin or official guidance from Volvo on this repair? Or is this something you have discovered/developed on your own?
There may have been an old tech bulletin 12-15 years ago, but it's just common knowledge among Volvo tech's these days.
 

·
Registered
Joined
·
672 Posts
Had the car at the dealer yesterday. Their tech said the noise was coming from the brake pads shifting slightly. They blamed it on the pads being akebono and not OEM. I didn't inform them of the previous diagnosis as I wanted a non bias opinion. I'm having trouble finding it, but I remember reading a thread about the brake pads making noise, but I remember there being a remedy and not just a response of, "oh it's not OEM".
 
1 - 20 of 21 Posts
Top