Brand new miata drive shaft u joint ?? Kitten inside...
 

Hi everybody...I can imagine than some of us have already changed a drive shaft, right ? :D

Brand new or refurbished one, could you just check on the vid below if the 4th axis which doesn't move freely could be an issue, considering that it is a BRAND NEW one...



Mandatory kitten picture, here is 2 wrenches for about 783gr so 1.3lbs :

https://www.miataturbo.net/attachmen...ine=1465241251

That's the weight needed to move the "hard" u joint :



Thanks a lot for your feedback/advice...

It's a little sticky. As long as there is no metal grinding, it's fine. It will loosen up in short order.

That's perfectly fine. It'll free up with use.

Yep, that's fine. Just changed one a few minutes ago.

Thanks mates, so the u joint involved is normally not worn...just for my information, can I do anything to loosen it a little ??

Then i'll tell you why I worry about that : with this driveshaft fitted, I had directly some vibration from the rear end at 65/70MPH, increasing but i didn't go a lot faster...
I checked the ppf height, still vibrating, 4 wheel bearings are new, I changed 4 tires and precise balance, still vibrating etc etc. FYI my car has a full 6 point cage, quite stiff.

Then, I only removed this brand new drive shaft (only drive about 30/40 miles with, very quick "test" above 65mph), put back my "old but finally fine" OEM one (which has finally 4 u joint axis ok, free without hard point etc) and the vibration disappear directly, even at 100mph !

When swapping back the OEM driveshaft, I didn't touch anything else, anything.


What is your conclusion ?? :likecat:

I'd be pretty surprised if an OEM shaft was out of balance, but stranger things have happened.

Take it to a place that makes or shortens them and ask them to check balance. It's a quick fix if it's out.

the shaft which occur vibration, with lazy u joint, in video, is not an OEM :o

Well there's your problem right there

Wanna say that its a bad balance from the supplier itself, on a new, supposed to be balanced, shaft ? ^^

Well it's not really a common problem at all, we've never even heard it on OEM shafts...so....

It is not an oem...unfortunately.

Did the balance process check only the shaft with ujoint in line so without "working" alternatively finally, or is it free/show also a ujoint failure/misalignement ?! Its an unusual issue so i try to diagnostic a little more...

You can also try clocking the shaft relative to the pinion flange. Four possible orientations. FSM states that OEM DS has index which should be aligned with casting mark on pinion flange.

Nice try, but FYI Emilio, the "OEM shaft which has to be marked to match the diff accordingly to the workshop manual" has been fitted at least 5 times on 3 different diff than the original one, on random position every time and never vib'. So thats hard to justify all of this vibration of the other one supposed to be perfectly balanced by that...maybe that could minimise it, especially if the diff has also a little bad round, but you also know that this diff has been refurbished brand new with every bearing new etc. I dont want to destroy it because of any wrong balanced load, even its hard vibration or a little less.

Try clocking it anyway like he said. If that doesn't solve your problem, turn that shaft into an art project and get an oem shaft.
Does it have a little weight tack welded to it somewhere?

the vibration issue is now solved with the old OEM one, which doesnt occur any vibration, either with random clock on random diff :bigtu:

The issue with this shimmy driveshaft is that the supplier is over atlantic (so huge shipping cost for and back and for, plus import fees etc) AND much less commercial/accomodating than i could have imagined...so I try to investigate by myself, in order to avoid an other bad surprise. If repair can done easily, i'll manage in a local way, better for everyone ;-)

I'll not use a 500$ drive shaft (yeap, incl. shipping and import...even more if considering repair or shipping back to supplier) as an art piece, i already have a sandblasted PPF for that ! :naughty:
Yeap, its a 5 yard joke for a useless drive shaft and will cost even more with shipping back (under my charge !!) or repair it locally...

I'm not an import/export specialist, but if the supplier finally refund me, i'll have paid for the local VAT (with custom fees) when import, but never get back that (because he want the part as a warranty return, value 0) ?!

So why did you get a $500 drive shaft while your OEM shaft was working fine again?

Because i refurbished the whole drivetrain during the winter after a diff bearing issue and wasn't sure that the OEM driveshaft was still in good shape, just correct or starting to worn.

I cannot manage every upgrade on my car by myself, especially when I need a correct lift etc to swap the drivetrain, so the workshop did itself.

I know that this OEM driveshaft has previously took 10 years of 13psi boost and hard tracked so I was expecting to avoid any later failure by putting some money on a well balanced new shaft with fresh u joint...but that was the opposite finally :crx:

That's the problem between preventive and currative maintenance, wait for the failure and dont drive the car for a while, or anticipate what can fail and refresh all that can be when it's possible to do/regroup with failure repair !

I am having the same issue with my non-oem driveshaft I just installed.

I noticed in the FSM it mentions clocking the stock driveshaft so that the sticker is aligned with the casting mark, I'll try clocking this one in other orientations as well. I may try re-checking the PPF alignment as well.

If I can't figure it out, I'll just drop the stock one back in for the time being. It has a couple gritty spots in the u-joints, but doesn't have the vibration issue.

Edit: since my non-oem driveshaft has zerks for grease, I'll try adding some grease just in case that was forgotten by the manufacturer, but I personally don't think this will help.

argh...is that a serviceable and balanced driveshaft from a known supplier ?

i forgot to answer to Monk, yes there are some weight but only on gearbox end, nothing on diff end...what about your non OEM balanced driveshaft weight ?!