Cruiserdrew
On the way there
I can't explain it, but look at the next virgin 80 that comes into your shop. They are 90 degrees out of phase from the factory.
Since the flanges cannot be parallel, normal driveshaft geometry does not apply anyway.
Driveline phase question (real time) (1 Viewer)
- Thread starter EricE
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
I can't explain it, but look at the next virgin 80 that comes into your shop. They are 90 degrees out of phase from the factory.
Since the flanges cannot be parallel, normal driveshaft geometry does not apply anyway.
- Joined
- Jul 20, 2004
- Threads
- 274
- Messages
- 23,205
- Location
- Chandler, AZ
- Website
- www.tontorecreationalliance.org
Agree that it is a unique setup, have never seen it on another rig, but so is the broken back thing. Have never seen an explanation for it, started 3yrs into production, without any other geometry change, so maybe just something that they found to be beneficial in testing?
On lifted rigs, some of us have found that changing to in-phase sometimes reduces or eliminates vibration. Have run stock rigs both ways, without detectable change, so
.
Mark W
Yep, I really don't really care that much I guess.
I wonder if there is any factory documentation of this to be found anywhere? Actual mention of it or explanation or instructions, rather than just the picture which does seem to indicate it.
Mark...
Mark...
The broken-back explanation is purely speculation on my part as to why the front driveshaft is out of phase. Both of mine were as indicated in the manual. Mark, have you actually laid eyes on your front driveshafts lately? Any of them stock height?
Mark W
Yep, I really don't really care that much I guess.
I looked at all 6 of my '80s today. 4 at the shop (3 FJs and 1FZJ) and 2 (Both FZJs ) at the house.
One of the FJZs (My wife's) sits on 2 inch OME, the rest of these are currently at stock height.
All of these shafts are phased with the ends aligned. I knew they were, but I doubled checked to be sure.
Had a couple of buddies out in their FZJs , but they are both lifted high with double carden front shafts.
Mark...
One of the FJZs (My wife's) sits on 2 inch OME, the rest of these are currently at stock height.
All of these shafts are phased with the ends aligned. I knew they were, but I doubled checked to be sure.
Had a couple of buddies out in their FZJs , but they are both lifted high with double carden front shafts.
Mark...
Last edited:
Weird, just checked the wife's and it's 90 out. Mine is a DC now, but it was 90 out.
All I know is that I had a bad vibration yesterday. Removed the driveshaft and placed it out of phase. Vibration gone...
Mark W
Yep, I really don't really care that much I guess.
In the time since I posted the above comment I have Changed to installing all the front shafts in the '80 series with the ujoints 90 degrees from each other. 7 and a half years comes out to a LOT of '80s through the shop. While my memory tells me the fully aligned worked just fine... my current experience tells me that 90 off does too. Since that is how the manuals do in fact show it, I have not felt any need to check and see if my memory is correct or not.
Mark...
Mark...
hamishpotter
SILVER Star
I have been chasing some stubborn vibes in my truck. I have also switched shafts a few times. I had not given this any thought.
this is helpful and may be a lead for me, so thank you
this is helpful and may be a lead for me, so thank you
Changed them to out of phase...
I just swapped out my factory out of phase front shaft with a rebuilt, in phase factory front driveshaft. No noticeable change in drive feels. Old one had lots of slip yoke play. I’m at 2.5” lift with 2* caster using rubber bushings.
- Joined
- Jan 12, 2008
- Threads
- 291
- Messages
- 3,493
- Location
- West MI near GVSU
- Website
- www.mcdesignsoffroad.com
I’m guessing Mr. ‘Yota hired a temp agency engineer who didn’t know about the phasing thing and simply drew representations of the shaft on paper-no one caught it and it was printed.
The simple physics of two u-joints in a shaft will not cancel out the vibes as Mark described previously. If the shaft is not flexing it won’t hurt, but the more the joints are flexed, the more the shaft between the joints accelerates and decelerates within each revolution.
The phasing of the driving and driven ends cancels this out.
This is why we use DC joints for the large angles. The joints inside cancel each other out through the H-housing, and then the other third joint at the diff must be relatively un-flexed during high speed operation-so with the pinion pointed at the driveshaft.
The simple physics of two u-joints in a shaft will not cancel out the vibes as Mark described previously. If the shaft is not flexing it won’t hurt, but the more the joints are flexed, the more the shaft between the joints accelerates and decelerates within each revolution.
The phasing of the driving and driven ends cancels this out.
This is why we use DC joints for the large angles. The joints inside cancel each other out through the H-housing, and then the other third joint at the diff must be relatively un-flexed during high speed operation-so with the pinion pointed at the driveshaft.
I had the front DS re-built a few months ago due to drive line noise and old u-joints. When the front was out the noise stopped all together. Re-installed per the FSM and the vibration/noise was reduced significantly. I do however still have some vibration when going about 60mph + and the torque goes from loading and unloading power. There's a small window where the noise/vibration happens. Yesterday i pulled the rear as its in need of re-building as well. Today ill drop it off at the DS shop to have it re-built. I have not driven the vehicle with the rear out to see if the noise is concentrated in the front...
