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Propshaft noises and vibrations
12-05-2012, 02:52 AM
Post: #11
Re: Propshaft noises and vibrations
Syncro ALH TDI, at idle, on the dashboard in between ashtray and instrument cluster.
[Image: 78123BE7-9A8D-48AE-A97D-E9A2BFCFD515-135...2E097A.jpg]


Here is a Stock WBX, at idle, just to the right of the engine decklid.
[Image: E73FBFDF-1703-4C1B-A839-9F73F430CE30-135...8A04B6.jpg]


[quote="Jon_slider"]my latest iPhone and Android app is called iseismometer

Here is the screenshot of my 85 2wd Westy @ 65mph, iPhone on the dash, on driver side of ashtray.

[Image: DA7B7491-7E46-46FD-B797-067445E8D1DA-429...7ACAFE.jpg]


And here's phone on dash, at idle and stopped
[Image: B08BAABD-EFB9-40C7-B1F9-3A5E8751C77B-429...10967F.jpg]


I started a thread here, that contains more discussion and screenshots
[Link]http://www.thesamba.com/vw/forum/viewtopic.php?t=532850[/link]

here is hans j's ALH TDi iseismometer screenshot, with his phone on body below the rear cushion, to right of decklid, at idle
[Image: 0E0037CF-7B17-43C6-813A-D094ABCFFB52-570...F6C74C.jpg]

note his Z axis, thats the up down factor

compare to my 2.1 WBX, also seismometer screen shot, phone also to right of decklid at idle
[Image: D01D02E7-5032-4646-BA85-E418FFB05A98-261...BACE8C.jpg]

see how little Z axis the WBX bounces
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12-05-2012, 12:46 PM
Post: #12
Re: Propshaft noises and vibrations
Thanks to Ian and Jon for your interest in this and informative reponses.

Jon, I cant see the pics you loaded but maybe my server not good signal currenlty, i will try later to view what you sent.

I have in the interim downloaded lots of tutorials on drive shafts, UJ's and angles, how to calc working angles etc etc etc. I didn't realise that it is such a science. One particular one has spreadsheets desined to calculate best angles and positions for any vehicle but one needs to be able to measure all the inputs quite accurately first. It seems good enough reason for a few new toys to do this :lol: I will get this right for fun and the process of learning if nothing else, i will keep you informed how i go.

Another thought is to put a cv joint on one side and perhaps eliminate all the hassle as suggetion by the copied and pasted blog. I do see that CV joints give way less problems. Obviously that would have to be made very well in the first place, but it is a consideration and not the first time I've heard it mentioned as an option.

Syncro, Sailing, Subaru, Scuba Diving, Surf, Sun, South Africa...
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12-05-2012, 06:03 PM
Post: #13
Re: Propshaft noises and vibrations
I have never seen a driveshaft with a CV joint. I do have a driveshaft with a Cardan joint, its just 2 Ujoints together, at one end, and a single Ujoint at the other, with a slip yoke.

the problem with these enhanced shafts is the added bulk and weight, of the rotating extra joints

IF you have one of the original driveshafts with rubber guibo, and your shaft makes pinging noises when you start from a standstill, it may have a bad bushing, plus it will vibrate inordinately. After you get your angles the same front and rear, consider swapping in a known good driveshaft as a test.

good luck getting to vibe free operation

---
Im editing to add the picture links with bogus code, so others can copy them, as the forum may or may not be showing these pics on your system. They do show on mine.

here is hans j's ALH TDi iseismometer screenshot, with his phone on body below the rear cushion, to right of decklid, at idle
[link]http://i6.photobucket.com/albums/y207/hans_j/phone/0E0037CF-7B17-43C6-813A-D094ABCFFB52-570-000000399FF6C74C.jpg[/link]
note his Z axis, thats the up down factor

compare to my 2.1 WBX, also seismometer screen shot, phone also to right of decklid at idle
[link]http://i974.photobucket.com/albums/ae228/jon_slider/D01D02E7-5032-4646-BA85-E418FFB05A98-2617-00000298C4BACE8C.jpg[/link]
see how little Z axis the WBX bounces
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12-10-2012, 04:20 AM
Post: #14
Re: Propshaft noises and vibrations
Jon,

what we call a u-joint on the stock propshaft is a cardan joint. 2 u-joints/cardan joints back to back (ie no shaft between them) make a double cardan and act as a constant velocity (cv) joint. What we often call a cv joint in our vans, the ones found on the driveshafts and made up of those balls, grooves, and cage Smile is also called a Rzeppa joint.

yours pedantically Smile

alistair

'86 syncro
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01-09-2013, 06:48 PM
Post: #15
Re: Propshaft noises and vibrations
Propshaft vibrations solved!

At last,after 4 weeks of solid groveling under the bus with lasers and strings and all sorts of other things, got to a point where I realised that if the stuff wasn't aligned now it was never gonna be :!: Including moving the actual engine on its mounting around to get it all straight, not just at the tranny and diff ends.
Also working angles at 2.76 degrees rear and 2.75 degrees front. Slightly shallower than VW original as the 2.6 motor lies a bit flatter. Still had a slight vibe at 50kms and 120km/h, so eventually went back to prop balancing.

This shaft has had inner bushes replaced and there is absolutely no play in the bushes. Also new German UJ's fitted by Stuarts guy. Balancing machine initially showed that it seemed to be in an acceptable specs but perhaps with bit of run out along the shaft plus the slight out of balance that may add up to be causing it.

So Shaft straightened (apparantly) to under 1mm run out across entire length and rebalanced two more times and suddenly ...got it :!: Big Grin :!: . No vibrations at all at any speed up to 140km/h.

Only thing now (as i need something to tinker with to be happy) is that there is quite a bit of noise feedback through shaft under deceleration, definately no vibration though, (unless this is a very high frequency vibration that makes the sound) which the boxer motors didnt seem to have :? . Maybe the roughness of the 5 cylinder does it? The diesels must make a racket then? Perhaps i'm too spoiled by also driving modern cars?

The other last funny thing is that from 120km/h upward I actually get what i can only describe as a "low whistling sound". Not unpleasant but i've never experiences that before? Perhaps the shallow working angles on prop causes it, which may be why VW went a bit steeper? Not really an issue as one doesn't drive these machines over 120kms really anyway....

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01-13-2013, 10:17 PM
Post: #16
Re: Propshaft noises and vibrations
Congrats on your success!

Only on these kind of forums can you get away with the statement "I envy those shallow U-joint angles" Smile

I have been revisiting the subject recently, I just published a blog post where I ramble on....


cheers

alistair

'86 syncro
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01-14-2013, 11:11 AM
Post: #17
Re: Propshaft noises and vibrations
Hi Alistair,

Please post url where you revisted and "rambled on" about UJ things as mentioned on your previous post, i would like to have a look.

Thanks

john

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01-14-2013, 06:00 PM
Post: #18
Re: Propshaft noises and vibrations
Oops, I thought I had posted the URL. Here it is, direct link to blog entry:

http://shufti.wordpress.com/2013/01/13/v...nts-again/

alistair

'86 syncro
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01-15-2013, 09:22 AM
Post: #19
Re: Propshaft noises and vibrations
Thanks Alistair, I have had a brief read and will study closely later plus the spicer info that you link to. I need to recheck some things, my last post i mentioned totally vibe free but wierd harsh noises on decelaration, so ofcourse I started fiddling again. Now have quietened things down but have got a faint vibration again that the 45km/h mark when under load only.

I made these changes by realigning the engine mountings at the back as i discovered using the laser across 4 points, ie the front diff mount, front diff flange, tranny flange and rear endmost seam of gearbox (only centre point that I could find and rely on for now as I have a 2.6 5 cyl engine) that the back of the engine was out of true slightly. Having the conversion means i dont have original engine mounting positions. It was out very slightly but upon straightening it the whole prop "sound" quietened down dramatically.

Why these things seem to be supersensitive i dont know, years ago i imported a new prop from Germany aus, when one still could, and i just bolted it on and off i went, no problems. I did still have the original 2.1 then so perhaps that made a difference. I think any conversion means having to really get the set up right again from scratch, which would have been done via factory years ago when VW first did the syncro.

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01-18-2013, 10:34 PM
Post: #20
Re: Propshaft noises and vibrations
congratulations on your progress and persistence

I want to highlight some aspects of Alistair's excellent writeup. It also has the best pictures on the topic of Syncro driveline angles that I have found anywhere on the net, reposted here for easy reference
[Image: proshaft-angle-1.jpg]

[Image: proshaft-angle-2.jpg]

[Image: proshaft-angle-3.jpg]


note Alistair does all his flange and propshaft angle measurements with his propshaft NOT parallel with the horizon, and uses the propshaft angle to adjust the measured angles of the flanges. The flange angles need to ultimately be measured relative to the propshaft angle, not the horizon. A Syncro parked on level ground will not sit with the propshaft level with the horizon, so you will always need to know the propshaft angle and adjust the flange measurements by the prop angle.

With some electronic angle tools, such as on iPhone, you can calibrate the tool so it uses the propshaft angle as Zero degrees, then the readings the device takes on the flange angles can be read directly, without adjusting. Just remember to re-zero your iphone clinometer app after you finish, so it goes back to true horizon level.

> I made these changes by realigning the engine mountings at the back as i discovered using the laser across 4 points, ie the front diff mount, front diff flange, tranny flange and rear endmost seam of gearbox (only centre point that I could find and rely on for now as I have a 2.6 5 cyl engine) that the back of the engine was out of true slightly.

Wow! Im impressed with the amount of work you are doing. Are your engine mounts moveable? glad its working out. Im beginning to hope you have a tire out of balance, it seems youve gone over the top on driveline alignment.

I am very concerned about lateral misalignment on my 5 cyl Tdi Syncro, but have no easy way to move the motor laterally.

Alistair's writeup goes on to address compound angles
"The above sketches show angles in a vertical plane, but you can imagine that the same thing could be going on if you could look down from above. The transmission and front diff. could be laterally mis-aligned. What is interesting, is the combined effect of both lateral and vertical misalignment."

I had some preliminary discussion about the impact of 1 degree of lateral offset on the vertical angle of the flange. It appears that each degree of offset laterally, increases the angle by 1/10th of the square of the offset degrees. so 1 degree lateral offset, raises the vertical flange measurement by .1 degrees as a compound angle. Similarly a 2 degree lateral offset, would increase the flange angle by .4 degrees.

> there is quite a bit of noise feedback through shaft under deceleration
> the back of the engine was out of true slightly.

I would be very curious to know how much lateral adjustment in inches at the back of the motor, or in degrees at the transaxle flange, was involved when you were able to eliminate the droning? noise on deceleration, by centering your motor.

It is great to read a thread like this, and to hear that some people have had success in eliminating vibrations by jiggling things around :-)
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