So far, it's been as much fun as this election....

 

Paying close attention here.... I have the same slight vibration, with just about the same symptoms, so I'll be interested in what you find....

T,

 

Fear not, I'll keep the thread plugged in til we have a solution.

 

Trying to be methodical and following advice in the thread -- went back and returned everything I could to how things were before the swap. Now that I had a way to feel more secure about accurate angle measurements, I started over. Was pretty sure I might need a bit more engine height to make things work. During the swap, I lowered the front of the car 3/8" for aesthetic reasons. I put the front coil overs back where they were before - 3 turns up in the front which gives a bit more engine height relative to the pinion. Then put the driveshaft in. Disconnected the rear torque arms and put screw jack under pinion. Disconnected tranny mount and put screw jack under tranny. Then played with angle finder. Ended up as pics show -- DS set at zero basis, see out of focus picture "0.0". Equal and opposite - about as close as I could get - 1.7 vs. 1.8. Tricky because the tranny mount compresses and sags a bit (cantilever) when it's weighted, so I had to guess at how much extra shim to use so it would end up where I wanted it - but apparently first shot, I guessed pretty closely. Also took rear reluctor off and removed the teeth I'd tacked to the slip yoke. You can see them in the picture.

Went for a drive. Still vibrating although I believe it's a bit less intense at the same speed. Next is to index rear flange - rotate it and bolt it up 90 degrees at a time until I'm all the way around -- see if that does anything. If not, then take DS to DS shop to check it out.

 

Well - interesting visits at a reputable local DS shop today, and an enlightening conversation with Frank at this shop who are about 45 minutes away -- http://www.driveshaftshop.com/ Seems we may have multiple things going on contributing to my symptoms. Rather than wait til "the end" -- figured I'd keep info coming as I digest it.

The DS repair shop immediately noticed wear on the slip yoke (input shaft) and was concerned enough about the wear and the tailshaft housing bushing interaction that they strongly suggested both be replaced. In fact, they wouldn't even balance it with my slip yoke because of it's condition. Pretty reasonable price to replace the slip yoke and rebalance --- and the DS needed weight on both ends, particularly on the pinion end. And then I remembered - when I put the Ford 8.8" rearend in the car 6-7 years ago, I had to change the pinion yoke to match the flange on the Ford (vs. the Dana 30 unit originally in the car). I did that -- and never even thought about the need to rebalance the DS! Brain fart - guess I got so excited about the new rearend, it just got right past me.

So - new slip yoke and balanced shaft. I'll get it in tomorrow and see what we have after a drive.

However, Frank at http://www.driveshaftshop.com/ gave me more food for thought. He told me the T5's are notorious for rear tail housing bushing wear (twice now in the same day) and also questioned me about how far the slip yoke inserts into the tranny. I didn't have a measurement handy, but when I took a look at the old slip yoke, it appears that a proper engagement would require a DS that's 3/4"-1" longer than the one I have. Story of my life.....

The obvious question to me -- why no problems before? Why no vibration when I put the Ford rearend in with the different pinion yoke? Why no problems up until the swap? Frank's best guess -- a combination of things. 1) Problems like this occur gradually - and gradual problems aren't as noticed over a long period of time. Translation -- perhaps it wasn't as smooth as I remembered it. 2) The LS engine is MUCH smoother/quieter than the old 5.0L -- the 5.0L NVH was masking some of the drivetrain NVH. 3) Poly mounts (engine/tranny) seem fine with the new, smoother engine. In fact, MUCH smoother/quieter than the 5.0L with rubber OEM mounts. However, the poly tranny mount in particular is terrible for transmitting NVH into the structure of the car; likely that the OEM rubber mount that I had in with the 5.0L was 'managing' some of what I'm feeling/hearing now.

So, I likely will end up replacing the tailshaft bushing and have Frank and the folks at The Driveshaft Shop build me a new driveshaft that's the proper length. And a switch to aluminum would damp even more of the NVH created by this 4'-rotating-shaft-tuning-fork hanging off the back of the tranny.

Hopefully this all helps others --- especially if they can get ahead of the symptom with their initial decisions. Stay tuned.

 

I hear c/f shafts absorb even more! ;-)

 

So they say!

 

MICHEAL YOUNT 2016 "Make Driveshafts Vibrate Again"

 

C'mon Doug - spell the author's name correctly. You had one job -- just to copy it....LOL! And good call - as I recall, you mentioned the bushing on one of your first posts, after we ruled out tires....

 

Curious to know what Frank recommended for engagement into the trans. I have heard bottom out the yoke, then pull it back 3/4 to 1".....did he have any thoughts? Mine is a 4L60E...

In addition, what are his thoughts on driveshaft angle. I see by your pictures that both are down angles. I was always under the impression that opposing angles was best, i.e., 1-3 down on pinion, 1-3 up on tail shaft....but no more than 4...on either..

T,

 

Mine aren't both down -- engine/tranny down at the back, pinion is up; pinion and output shaft are parallel. Frank would like to see not much more than an inch between seal lip and the perpendicular face of the yoke. I've got about 1.25" there. If your seal has a dust boot as mine does, careful not to mix that up with the actual seal, which sits just about even with the back of the tranny case.

 

Cool....no dust boot, just seal, will check distance but I think I'm good.....

What are his thoughts on max/min on the respective angles?

Thanks for the feedback..

T,

 

When I told him I was parallel and 1.7/1.8 his comment was "that's just about text-book perfect". On my 1.25" clearance based on a .75"-1" ideal he said, '...well it's not terrible...', implied he wouldn't change it just for that if it seems to be working. He did suggest I move away from the poly mount if harshness is still an issue.

Edit - of course, all of this was additive to - be sure the driveshaft is straight, balanced and can manage rpm without going critical.

 

Note on driveshaft re-install -- that new slip yoke is a MUCH tighter fit in the bushing than the old one was. Test drive -- S-M-O-O-T-H as a gravy sandwich, at least relatively speaking. Clearer than ever that I have a world class problem - now I've got an engine that's so much smoother/quieter than the old Ford lump, I'm cursed with hearing lots of other stuff courtesy of poly bushings in the suspension too. Who'd've thunk? Well, I reckon it was predictable.

Now --- I am going to work a bit of rubber into the shim-xmem-polymnt sandwich and see what that does. And won't go long without getting my hands on the tool that allows me to change the tailshaft bush without removing the housing....pain in the **** because of how the tranny fits my funky shaped tranny tunnel. And get my DBW cruise control in -- and it'll be done with everything working as it did before - with a lot more power/refinement.

Thanks for the help everyone.

 

now you need a turbo

 

Ah - truckdoug, you have a bad case of PPD - possessive pronoun dyslexia. You've confused what you want with what I want.