Metal hammering sound? (Solved: U-Joint)

[jiggersplat]

More frequently than not lately, I have been hearing a metal hammering sound when pulling away from a stop or slowing to a stop. It may be occuring at other times, but the wind and road noise is drowning it out. The sound is most noticeable backing out of my driveway and coming to a stop while the car is in reverse. It's definately metallic sounding and does not appear to be the exhaust as far as I can tell. Anyone else experienced this?

[Ilya]

Is it possible to get a quick video clip from your phone and share it on one of the filesharing sites?

[jiggersplat]

I'll see if I can grab one next time I'm in the car.

[jiggersplat]

Here is a clip

https://youtu.be/9rI-TqYAdmA

I got it up on a lift this morning. The front u-joint on the front drive shaft has failed.

[Ilya]

That would do it, and I believe we've had a few of those posts over the years. I updated the thread title.

[cruzad3r]

what exactly is the front u joint? any pix?

[TDot]

what exactly is the front u joint? any pix?

Its the thing that holds on to the wheel components and makes it spin. Google it for a pic.

My question is how did you figure it out, or are you a mechanic? What indications make it apparent when you look at it or shift it around that it is failing?

[jiggersplat]

U-Joints are "universal joints". They basically allow you to have a "bend" in a drive shaft. If you have a wobble socket adapter, that's a u-joint, or if you've ever seen the driveshaft of a box truck, you'll see a big u-joint in the middle of it.



I had it up on a lift. You can grab the drive shaft with your hand and feel that it has slack in it when you twist it. and you can hear it bang. A good U-joint should not have any slack in it or stiff spots.

[FlawleZ]

The question is is this a replaceable part or do you have to purchase a new driveshaft? Nissan has has a history of not always making their driveshafts and ujoints serviceable without replacing the whole assembly.

[jiggersplat]

This one, at least according to the the parts fiche is not replaceable. However, if you search for the drive shaft part number you'll find a couple places listing just the U-joint.

The drive shaft part number I found is 37200-CL70A. It seems to be interchangeable with a couple different years of G35, FX and EX's.

Here is the U-joint I bought... figured it was worth a shot @ $22. Don't know if it will actually fit or not.

http://www.amazon.com/37200Cl70A-Univer ... B00DMA7U3U

I also ordered the DORMAN 938320 driveshaft which is not shown to be compatible with the M35/M45 but is compatible with G35 models that use the same part. It also specifically states that it has a replaceable u-joint so if it happens again I'm not buying a whole driveshaft. $325 or so from partsgeek.com and 30 day returns if I get lucky and can replace the U-joint.

[JacksonMann23]

I just had my driveshaft replaced last week. Had the same sound on my 06 M35x but it was MUCH louder. Ordered the driveshaft from RockAuto and a driveshaft seal and paid 170 to have it installed. Dealer wanted around 700 for it. From what I was told once that U-joint goes out you have to replace the whole driveshaft.

[jiggersplat]

Was the seal necessary or did you just do it at the same time since you had the driveshaft out?

[jiggersplat]

For the record, my shop was not able to replace the u-joint with the one purchased from the Amazon link, and ended up replacing the whole shaft.