Scott, I've been working on my fiance's 2005 Mitsubishi Endeavor automatic AWD with 195K miles. The vehicle is in remarkably good condition and has minimal rust despite the mileage and living in the Northeast. I've replaced the front tie rods, links, and bearing hubs, and flushed the auto trans, with each repair successfully correcting different issues. When I first drove it I noticed that when pressing the gas pedal while coasting the car makes a thumping noise suggesting something loose in the drivetrain. So I pushed on the driveshaft and felt it move sideways suggesting the carrier bearings (2 of them on this assembly) need to be replaced. When I shop for parts such as the u-joints and the carrier bearings I can't find anything. Instead, listed for sale is the entire driveshaft assembly. Searching the forums I find that most people suggest the entire assembly needs to be replaced. My question is: How do professional mechanics determine if a particular part in an assembly can be repaired, or if the entire assembly needs to be replaced? Is it worth it for me to try and rebuild the drive shaft or am I going to need special shop tools such as presses, torches, etc? Thanks for what you do.
Do you have a shop near you which repairs/rebuilds driveshafts?
Thanks for your suggestion. I was looking to pay zero labor and DIY it. However, I'm sure I can find a shop and get a quote. This is an unpopular vehicle though and rebuilding the original drive shaft by a shop may not be worth it.
So what is worn, the carrier bearings, u joints or both? U joints usually take most of the wear in a drive shaft and I would not hesitate to replace those if they are the problem. The easy and expensive alternative is to replace the entire driveshaft as an assembly.
I took a closer look at this assembly and nothing is broken off or any torn rubber. The u-joints feel held together well. The trans-axle housing does leak a little oil/fluid around the drive shaft port seal, probably normal for an old car. I noticed the center supports/carrier bearings are bolted to the chassis with rubber bushings. The bolts are firmly in place although they probably have never been re-torqued. However, there appears to be a lot of play on the carrier bracket pivoting on those mounting bolts, curiously more on one of the carriers than on the other. This, combined with the play in the carrier bearing rubber bushing I noticed earlier could be causing the whole thing to wobble like a pool noodle, much more than what is supposed to when new. Replacing the mounting bushings could be an inexpensive alternative to replacing the whole assembly.
I’m not a mechanic, but the mechanics I go to usually go with the cheaper and time efficient option for the customer. I’m not sure about u-joints and driveshafts. But I’ll use struts for example.
It is more cost effective and time effective overall to just bolt on and off the an old and new strut, than to decouple the shock absorber from the spring, compress the spring, attach the new shock, and reinstall the strut.
Same goes with boots on axles. They will replace the entire axle, rather than just the boot. Because it takes just as much time and money to do the boot alone than the entire axle.
That is, unless specifically requested by the customer, it seems replacing the entire assembly rather than the tiny part, is more time and cost effective on most parts for professional mechanics running a business.
If replacing the tiny part is more time and cost effective, I would bet they would go that route too. At least with my trusted mechanics.
Granted all mechanics are different, and this is just my anecdotal experience with the non-dealer mechanics I have gone to.
Going to the dealer on the other hand, they will usually give the more expensive option, and options adjacent to the actual thing that needs to be fixed.
With your specific problem, price out the labor and parts cost for doing the whole assembly, versus doing just the small part. Go with the cheaper option, assuming the quality is there both ways.
I appreciate you taking the time to comment. While I'm familiar with the impracticality of oneself rebuilding things such as struts, half-shafts, transmissions, and differentials I was surprised by the lack of parts for this drive shaft assembly. After watching a few videos of u-joint replacements and even one dude hammering out the two ends of a shaft from the carrier bearing I was so convinced it could be done on my driveway that I ordered a cheap u-joint removal kit from The Rainforest. But then I couldn't find the parts (I'm keeping the tools though). I am trying to save my emergency fund for when a major repair that is beyond my abilities is needed. I'll continue to swap parts myself until I have to get rid of it. I would like to know what others think is possible despite today's rebuilt-part-swap economy.