Driveline damage, Post tranny
06-25-2010, 08:31 AM
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Driveline damage, Post tranny
title about sums it up. I have aquired a wonderful rotational/grinding type noise from the rear of the car. here's how...
Few days ago i was driving into Holland, leaving a highway fuel station i was forced into a curb by a clueless Aston Martin driver. I'll skip trying to explain the nitty gritty as that isnt the point anyway.
Point is, i hit a ~5" curb on the drivers side. Hit front and rear wheels nearly squarely, so there is no body damage no curb hopping etc... rashed up the OE wheels which i dont care about, and whacked the alignment.
*** see my next generation artistic portrayal. note how i've drawn how i caught the curb squarely, but at a glancing angle, not perpendicular into the curb.
The next day i got the car on the lift, the alignment equipment was out of calibration so i couldnt correct that yet. But otherwise there was no visible damage of any kind other than the curb rash on the face of the wheels. The sound I am developing was not reproduced by free spinning the wheel on the lift. The sound is also very odd in frequency/speed of the rotating/grinding... it is obviously tied in frequency to wheel RPM not engine/tranny. But the frequency is significantly slower than wheel/hub rotation speed.
I figure the 2 most obvious things are the hub and the rear end itself. The sound, although not an obviously noticable one, most definately comes from the rear of the car(axle area). Although i think it's probably hub/diff related, the speed of the sound and the fact i was unable to reproduce it by spinning the wheel/hub makes me want to see if anyone else has other ideas to look out for, or how i can test the diff sinc e it doesnt work the same when spinning wheels in the air as it does on the road...?
Few days ago i was driving into Holland, leaving a highway fuel station i was forced into a curb by a clueless Aston Martin driver. I'll skip trying to explain the nitty gritty as that isnt the point anyway.
Point is, i hit a ~5" curb on the drivers side. Hit front and rear wheels nearly squarely, so there is no body damage no curb hopping etc... rashed up the OE wheels which i dont care about, and whacked the alignment.
*** see my next generation artistic portrayal. note how i've drawn how i caught the curb squarely, but at a glancing angle, not perpendicular into the curb.
The next day i got the car on the lift, the alignment equipment was out of calibration so i couldnt correct that yet. But otherwise there was no visible damage of any kind other than the curb rash on the face of the wheels. The sound I am developing was not reproduced by free spinning the wheel on the lift. The sound is also very odd in frequency/speed of the rotating/grinding... it is obviously tied in frequency to wheel RPM not engine/tranny. But the frequency is significantly slower than wheel/hub rotation speed.
I figure the 2 most obvious things are the hub and the rear end itself. The sound, although not an obviously noticable one, most definately comes from the rear of the car(axle area). Although i think it's probably hub/diff related, the speed of the sound and the fact i was unable to reproduce it by spinning the wheel/hub makes me want to see if anyone else has other ideas to look out for, or how i can test the diff sinc e it doesnt work the same when spinning wheels in the air as it does on the road...?
06-25-2010, 12:00 PM
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yeah thats the obvious one.... and i think i simply cant roll the wheels on a lift and replicate because i cant spin em fast enough, or because theres virtually no load on the bearing comparatively..
just thought i'd throw it out to see if there were any other thoughts. that hub is getting replaced and i'm gonna peak at the diff all as soon as its viable for my schedule
just thought i'd throw it out to see if there were any other thoughts. that hub is getting replaced and i'm gonna peak at the diff all as soon as its viable for my schedule
06-25-2010, 12:04 PM
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oh, i also kinda threw this out here just to see if anyone would comment on the Aston Martin....
fwiw thats the 3rd such car that has almost plowed through me... the others were a Ferrari California and some older model... 355/Testarosa looking. i see a LOT of nice cars out here. havent seen a Veyron, but pretty much anything else i think i've seen around
fwiw thats the 3rd such car that has almost plowed through me... the others were a Ferrari California and some older model... 355/Testarosa looking. i see a LOT of nice cars out here. havent seen a Veyron, but pretty much anything else i think i've seen around
06-25-2010, 01:14 PM
#5
I think I see the problem; your rear right wheel is significantly smaller than the others! 
But seriously, I didn't see this covered, but maybe you have a bent wheel? Try balancing the two that got whacked? I know that doesn't necessarily account for the grinding noise, but could it be influencing the bearing?
But seriously, I didn't see this covered, but maybe you have a bent wheel? Try balancing the two that got whacked? I know that doesn't necessarily account for the grinding noise, but could it be influencing the bearing?
06-25-2010, 01:19 PM
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I think I see the problem; your rear right wheel is significantly smaller than the others!
But seriously, I didn't see this covered, but maybe you have a bent wheel? Try balancing the two that got whacked? I know that doesn't necessarily account for the grinding noise, but could it be influencing the bearing?
But seriously, I didn't see this covered, but maybe you have a bent wheel? Try balancing the two that got whacked? I know that doesn't necessarily account for the grinding noise, but could it be influencing the bearing?
wheels arent bent, still balanced. bent was my initial big fear till i got em on the machine
06-25-2010, 02:53 PM
#8
How about the ujoints on your rear half shaft are fractured. It's amazing how long a u joint can go busted, but it's gotta be u joint inside or outside on the half shaft. It could also be the wheel bearing or rear diffeferential bearing.
Next time let the Aston Martin hit you; Oh, I see you're not in California so you actually try to drive responsibly!
Next time let the Aston Martin hit you; Oh, I see you're not in California so you actually try to drive responsibly!
06-25-2010, 03:57 PM
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How about the ujoints on your rear half shaft are fractured. It's amazing how long a u joint can go busted, but it's gotta be u joint inside or outside on the half shaft. It could also be the wheel bearing or rear diffeferential bearing.
Next time let the Aston Martin hit you; Oh, I see you're not in California so you actually try to drive responsibly!
Next time let the Aston Martin hit you; Oh, I see you're not in California so you actually try to drive responsibly!
this is my first solo incident of any damage, i've been tagged in the parking lot before though. but i've been in more than a couple off road excursions avoiding collisions. and out here in the areas i like to go drive, more often than not its those type of vehicles* that are the worst dangers on the road
*Aston Martin, Ferrari, Porsche high ends, Lambo, Maseratti, etc...
theres a Gallardo here in Mons that tears it up once in a while but ive never seen that one wreckless
06-25-2010, 04:07 PM
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i didnt do this when it was up because i was under the impression that without being under a "load" the diff wouldnt operate properly anyway, perhaps enough to verify a symptom, but not enough to rule one out
thanks for mentioning it though, i'll give it a go also
06-25-2010, 04:13 PM
#12
When I had to get a wheel hub bearing replaced I was also unable to reproduce the noise on the lift. There was just not enough load being put on on the walls of the hub-bearing contact point. It sounded like I was driving with mud tires on. I replaced that whole hub and the sound was gone.
* I'm using 'load' in terms of weight, not drivetrain load
* I'm using 'load' in terms of weight, not drivetrain load
06-25-2010, 04:19 PM
#13
Use a chassis Dyno instead
I wouldn't recommend wearing a neck tie when you crawl under there ...
You do own a mechanics stethoscope don't you? It can assist with pinpointing specific noises you might not pick up on otherwise.
.
I wouldn't recommend wearing a neck tie when you crawl under there ...
You do own a mechanics stethoscope don't you? It can assist with pinpointing specific noises you might not pick up on otherwise.
.
Last edited by TeamRX8; 06-25-2010 at 04:22 PM.
06-25-2010, 04:41 PM
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almost, i'm up to here in chocolate, waffles, and the best beer in the world!! Germans can keep their schnitzel 
though i do like kraut...
and hey, whats to be sorry for? I'm in the middle of SpaFrancorchamps, Nuremburgring, Hockenheim, Zandvoort, and half a dozen other tracks in single day trip distance
oh and the best ***** F'ing fries you've ever had in your life!
though i do like kraut...and hey, whats to be sorry for? I'm in the middle of SpaFrancorchamps, Nuremburgring, Hockenheim, Zandvoort, and half a dozen other tracks in single day trip distance
oh and the best ***** F'ing fries you've ever had in your life!
06-25-2010, 05:34 PM
#19
Ok then, you suck 
pulling the hub and changing the bearing is a lot of fun, trust me on this one .... you will be much better off getting a good used upright/hub assembly because for all you know the upright is tweaked too.
.
pulling the hub and changing the bearing is a lot of fun, trust me on this one .... you will be much better off getting a good used upright/hub assembly because for all you know the upright is tweaked too.
.
Last edited by TeamRX8; 06-25-2010 at 05:38 PM.
06-26-2010, 04:40 PM
#24
I know you say the noise is from the rear but if you haven't taken the front wheel off and checked the front bearing you should . I spent months trying to diagnose a sound I could have sworn (along with several other people) was from the rear and it turned out to be the front bearing.
06-26-2010, 05:04 PM
#25
Not a day goes by that I don't think about Brugge.
Wheel bearings move around their race at a fraction of wheel rotation speed. That is why the sound is off.
That said, there are a bunch of things to check with regards to something simply making contact when the suspension is loaded.