TheSamba.com :: View topic - Syncro Vibration and at the end of my rope

Fri May 22, 2015 12:51 pm

Hello Sambas
I realize this subject has been beaten to death and Im not trying to ignore previous postings...trust me I have read every one of them in detail...

I have reached out to one or two of you on this issue but I thought I'd try a broader approach since I am still at ground zero in figuring this out..
Figuring what out you say..? Let me give you the back story

I have a '90 syncro Westy that we bought about 4 years ago. It was a one owner rig with typical wear.. it needed a few small items but was in decent shape short of cleaning...lots of cleaning. Prior to picking it up from the PO he insisted the the drivers/left front axle be replaced...the boot was ripped so I thought "cool, bonus..he wants to replace the whole thing" ...more later on that. Also I had the front wheel bearings redone since it was 1/2 torn apart.

About 18 months ago I heard the tell tale "ping" during shifting of Ujoints going bad in the prop shaft. Pulled it out and it was shot...I elected to replace the shaft with a slip yolk via my local shop here in Seattle. After getting the new shaft put in I had the vibration right away at 34-50mph, the issue that seems all to common in these posts. My mech replaced it with a different new shaft..same thing..made my cabinets rattle like mad at 35. I had already purchased a GoWesty decoupler so we decided to have that installed...no difference. It made pretty much same vibes decoupled or coupled.
At that time we discovered the front diff had a little slop in the final drive and I was certain the VC needed a rebuild too so we pulled it and rebuilt the whole thing via AA transaxle. Reinstalled in with no change in the vibes. We swapped that diff with a different differential...nothing. In fact after driving it around for 50-60 miles it corrupted the seal in the front diff and it started leaking... so fixed that. I then redid all the bushings with new poly ones, new front diff poly bushings, steering rack and transmission bushings as well...in that time I put new CLK rims, tires (yup balanced), springs, OME shocks, bigger brakes kit, new rear wheel bearings and I took out the shaft and had it checked and balanced 2 different times AND tried an OEM shaft out of a different syncro...I still vibrate. A Lot!...as in I cannot see anything in the rear-view mirrors over 50 mph ...forgot to mention we checked the flange angles and shaft angle...I dont recall the numbers now but they were sub 4º
My last attempt was to replace the front axles with Lobro ones since the "new" one I spoke of at the start of this was a Chinese Empi ... That seemed to change things slightly in that the speed range for the vibration changed to 45mph on up.
Also of note the vibes are nearly non existent with the shaft out...maybe a slight vibration but I am so hypersensitive now I cant say for sure.
I planned on fixing/replacing most of these items anyhow (we plan on keeping the rig for a while) but I cannot for the life of me figure how a simple shaft swap led to a seemingly incurable vibration. We are all at a loss...I am at a year and half of fixing and not really driving my buddy....
What can I look at next? The only thing left really in my mind is a tranny rebuild....?? :shock:
Thanks guys

Fri May 22, 2015 2:02 pm

Have you tried the laser level method of checking the angles? That seems like it would be the most accurate.

Some aftermarket shafts don't self center. You have to adjust them through trial and error. I think the stock ones ride in a groove and can't get off center. Maybe it isn't that if you also tried an OEM shaft and it still did it. Or maybe the OEM shaft is unbalanced and the aftermarket one wasn't centered, or is also unbalanced.

Fri May 22, 2015 2:17 pm

I had a similar experience with my Syncro. It took some time, but I finally got the vibration to cease.

I would remove the propshaft and go take your van out for a drive. See if it makes your vibration issue go away.

If it goes away then you should only be looking at flange angles, propshaft balance, and a straight alignment between the front and rear flanges. If it is still there, when driving without a driveshaft, you are looking at the cv joints, half shafts, tires/wheels, etc. This simple step will really help.

Mine ended up being the flange angles were to unequal. Also you want to make sure the front diff and transaxle are lined up. Either a laser or plumb string to line up the ribs on the housings. I ended up using a string line from the engine mount to the front bumper to get a straight line and then re-positioned the motor mounts, transaxle mounts, and front diff mounts to line up the ribs. I really took some time here to get everything lined up.

You can also loosen the (3)three front diff bolts and see if your vibrations calm down.

This is a very frustrating thing to get worked out, but it is worth it for the longevity of your now very expensive transaxle. Lots of vibrations with a hot tranny will lead to an early failure and a loss of green from your wallet.

Good luck!

Edit: I also need to note that I have an early KEP EJ22 Subaru conversion.

Fri May 22, 2015 2:36 pm

The fact that changing the cheap front axle made a difference would make me want to take a closer look there. Could the flange on that stubaxle be damaged or out of wack? You tried it once with the prop shaft off and where not sure if the vibration was there, how about the reverse? Prop shaft on and coupled and the front axles off. Might help further isolate the source.

Hans

Fri May 22, 2015 4:55 pm

I have a little time this week-end. I'll mess with the angles again and remeasure them and try some shimming if necessary.
From what I am seeing here, both the front diff and the rear tranny need to be at the exact same angles ?. Say 3º down each...am I aiming to have the shaft at close to zeroº or barely 1º ?
I dont have the laser tool to align front/back ..Jael I am not sure I understood the plumbline method you described. You tied off to the engine mount and eyeballed it in relation to the trans axle housing ribs..just measured the gap in the line/housing relation?
Hdenter I am pretty sure the axles are good now...I put complete rebuilt/new Lobros in from VanCafe...stubs should be great. Is it possible the wheel bearing was pressed in crooked? I am not certain the shop that did that work from the PO new what the hell they were doing....paperwork showed 6 hrs of labor!!??!!

Thanx all for the input...I'll keep updating as I go.

Fri May 22, 2015 5:00 pm

Here is a pic (pre springs and wheels) .....feeling sentimental about my ride I guess...

Fri May 22, 2015 5:46 pm

Have you tried the Van Cafe method of aligning the front diff.

if that fails, move on to shimming the front diff..

the goal is to have the front and rear angles match, within 1 degree

the first thing you can modify is the two bolts at the back of the front diff can be shimmed, to reduce angle.

see the shims in middle of this pic

Changing the angle at the back is more complicated, just try to make the front one match it as a first step

regarding the prop shaft, you want the angle it creates with the flange

the angle of the flange relative to the prop shaft, not relative to the horizon

example

+4/0/-4 is

4 front flange aims downward towards rear of the vehicle, relative to horizon, 0 prop relative to horizon, -4 rear relative to horizon, flange aims downward towards front of vehicle

but
+3+1-5 is also CORRECT, flange angles relative to horizon still, but adjusted for the propshaft rising upwards towards the front by 1 degree.

that increases the angle to the front flange, and decreases the angle to the rear flange, relative to the horizon.

Did I confuse you? Or bore you to tears by stating the obvious :-)

to avoid getting the math wrong, for the propshaft angle, you can either calibrate your angle reader to the propshaft as its zero angle setpoint, or you can jack up the rear of the van until the propshaft is at zero degrees relative to the horizon

again sorry for being so basic, I dont know what your angle measurement device or experience is..

good luck, bad vibes suck
you can kill it.. its your propshaft if as you said, it goes away when you remove it

and yes, youre now hypersensitive and feeling lots of other things, axles, even tire pressure.. breathe :-)

Fri May 22, 2015 11:02 pm

Some great advice here. I had a freshly rebuilt original drive shaft that turned my Syncro into a shaker from completely smooth. Brought it to the driveline shop here in Post Falls, ID on Seltice Way. He used a jig he created for another multiple Syncro owner to align and balance it and instant smooth goodness.

I agree with the comment wondering about the half shaft making a difference. Hmmm...

I am puzzled that a smooth driveshaft from another Syncro that is known good did not smooth yours out. Between that, and the half shaft comment, I'd recheck the front wheel bearing issue. The front wheel bearings on the Syncro are completely different from the 2WD and I would consider leaving the driveshaft alone for now and revisiting that work. Sucks, because those are expensive seals and bearings, but the special nature of that work being done by a hack shop makes me wonder what you will find in there. A mashed bearing race (these are pressed in, not shade tree bearing types like the 2WDs), a crooked bearing, a race not pressed in all the way home. All on the possibles list.

Revisit driving without the drive shaft in to confirm in your own mind if the issue remains. If so, open up those front bearings.

Sat May 23, 2015 6:10 am

In 15 years of eliminating vibes from Syncro vans, I have not "shimmed" a single mount.

Process of elimination is how the OP will find what is out of whack.
It is a very long process and notes should be taken.

Wish I was closer, I would put it on a hoist and find the issue.

If the van has the original transmission, it is time for a proper rebuild with upgrades.

Sat May 23, 2015 8:20 am

Have you tried another set of tires yet? Just swap all four from a smooth van.

Sat May 23, 2015 9:26 am

Everything round should be spun balanced by a professional.

Sat May 23, 2015 10:21 am

What is it about the T3 Syncro driveline design that contributes to vibrations? I've been a longtime member on MB and Audi sites, and don't remember ever hearing of problems with their shafts...ever. A center slip yoke with bearing support seems like one crucial difference that folks might consider as a design upgrade. I've driven exactly one Syncro, and it had a nasty vibration that I've not revisited and resolved

Sat May 23, 2015 10:28 am

This post is timely indeed.

I just rebuilt my trans with the works: new alum case, etc.

Same slip yoke drive shaft went back in. I have some vibration only in 2nd between 3-4k rpm. It's only in that gear and in that powerband and only with prop shaft is engaged/coupled. It's not noticeable in 2wd when decoupled.
In addition, I may have slightly more vibration at highway speeds in 2wd and not when coupled at highway speeds. Although that could be me overly paranoid :).

Would that be a prop shaft balance issue? Or perhaps the front diff and trans not perfectly aligned? I did try the van cafe method of loosening the front bolts. I haven't measure angles yet.

Would it be worth my while to remove the prop shaft all together?
The issue didn't exist before trans rebuild.

Sat May 23, 2015 10:32 am

Zeitgeist 13 wrote: What is it about the T3 Syncro driveline design that contributes to vibrations? I've been a longtime member on MB and Audi sites, and don't remember ever hearing of problems with their shafts...ever. A center slip yoke with bearing support seems like one crucial difference that folks might consider as a design upgrade. I've driven exactly one Syncro, and it had a nasty vibration that I've not revisited and resolved

Quattro Syncro has the center bearing carrier mounted with a two piece driveshaft from the donor vehicle.
Smooth as silk and the flange angles would raise a few eyebrows for sure.

Sat May 23, 2015 10:34 am

Certain decouplers have been known to allow for slight vibes when decoupled.

Mon May 25, 2015 4:33 pm

Been a few days with no progress....I really gotta get rid of this "job" thing as it wrecks all my free time to do things I want to do!

So finally got a couple hours to mess with the angles and tale a good look under there today. Borrowed my friends angle level that has a digital read out. I jacked up the van and put it at dead level zero via the frame..inside floor and front/rear bumpers. I figured 4 points at zero I cant be too far away from perfect flat.
The rear flange off the tranny is 2.4º down and the front transaxle was 4.1º down.
Also I made my own rig/jig/thing out of some left over metal pipe cap. It fit over the flange perfectly...drilled a hole in the end and put a nice laser pointer in there...tadaaa! A cheap-O alignment tool.
Everything looked pretty good....maybe a tad off but only say 2 mm left pointing front to rear.
I know Insyncro says never shim things up but I going to try it and see what changes it produces if any...
More to follow
LeeB

Mon May 25, 2015 5:18 pm

Here is my experience with my ex-syncro, i went to the syncro yahoo group and copied my message... In march 12, 2009! Wow! Time flys!

Quote: Since there's all these messages getting around, I felt it was time to share my experience with some syncronuts, and hopefully some of you will make a better diagnostic before spending all that hard earned cash. Keep in mind that I did get help from this list, and from the french syncro list from Quebec

http://cf.groups.yahoo.com/group/VW_SYNCRO_QUEBEC/

to try to get it fixed, to no avail (some of you might remember my postings)... Read on... Sorry for those who don't like long postings, but I cannot find another way to make it shorter, as english is actually my third language. Feel free to write me back if something is not clear.

Sorry for coming in the threat late, as I check my emails 1 to 4 days later, depending of work... I wanted to write this a while back, but still did not get around to do the final step (the final laser alignment).

My actual "gauge" to mesure vibration is the center rear view mirror while driving. It's the first thing that I notice vibrating, even before feeling it in my pants (from the seat, or steering). So I always keep a very close eye on it. When it vibrates just a little, I can see tru the center rear view mirror, the rear window starting to "double vision" very little. When there is a lot of vibrations, well it's like I can see the double vision vibrating so wide that I cannot recognise any car in the mirror. The rear side mirrors also vibrates a lot when there is severe vibrations, or what I call severe, it is actually hard to say over the net and to not actually see it in person.

My vibrations always comes between 60 km/h to 80 km/h (approx 40 to 50 MPH). And for some reason you can feel a very little vibration at 40 km/h (25 MPH?) when accelerating only, not decelerating... Go figure... When I tried to stay at 40 km/h (25MPH?) I hardly can keep that little vibration spot on. When there is very little vibrations at the 60-80 km/h mark, I cannot feel the 40 km/h one.

I actually did a lot of tests, thanks to an extremely friendly vw shop near my house and it's owner Uwe, a german mechanic (of course!). And they deserve the credit: "Les moteurs Carrera", in Laval, a suburb north of the Montreal city, in Quebec, Canada (ph: 450-669-3240).

In this shop, we did losts of tests, road tests with driveshaft on, without driveshaft, tests on the lift with the wheels off the ground with the motor running and wheels at speed, with driveshaft on and out, with wheels, and with out the wheels also (believe it or not I had one wheel not properly balanced and we though we found the cure, but no, the driveshaft did vibrate less afterwarths, so it was part of the problem). We also did tests with a metal "stetoscope". It is something that actually some mechanics use to feel vibrations from worn out bearings. My bearing at the nose cone of the transmission did make lots of noise there, but it was not a problem as we found out later (transmission mount)... Another friendly mechanic shop, VAPS vw shop in the south suburb of Montreal (450-346-0457) lend me their vibration free driveshaft for testings. I am lucky to have these two good shops around here. That driveshaft also vibrated on my f*&?% syncro!!!... I was mad... But I did find my solution at the end. And no it was not pushing the syncro down a cliff (well, for lack of cliffs in the area... hummm, this syncro got lucky). It is not possible for me to remember all the little details of these tests, so don't expect a full on diagnostic with all the different tests, sorry.

So here is my "short" story:

1- Driveshaft vibrations problem part 1: get new u-joints and a new rubber mount then get driveshaft balanced, still vibrates. They later told me they can only balance without the flanges at each end of the driveshaft?? So they balanced the tube only basically, at the u-joints, with no flanges. Great...

2- Driveshaft vibrations problems part 2: go to a second driveshaft shop, get it balanced again but with both flanges on: still vibrates, but less. This means it had to be balanced all together. It's here we started all the tests... We even made a homemade laser alignment tool, made the appropriate alignment and we managed to diminish the vibrations, but not eliminate it. And after some luck I had the driveshaft on the syncro, I put my hands around the rubber donut, and with my weight pulling down, I FELT A SLIGHT MOVEMENT AT THE RUBBER DONUGHT!!! Arrrgh... It was very little, but it was enough to trow out the balancing. With the help of a machinist, we found out the inner bronze bushing was badly worn out, and the only way to fix it was to separate the tube from the u-joint flange at the weld, replace the inner and outer bronze bushing with precision machining, re-weld the tube and u-joint flange back together. Then rebalance for a 3rd time, Yes you read right.

3- Driveshaft vibrations problem part 3: get driveshaft balanced again, after machining - Still vibrates!!! But to a minimum acceptable somewhat. I cannot believe it! Anyway I don't want to go on with what was going tru my head, lets just go to the fix. This is when I contacted VAPS VW shop and ask if they had an extra vibration free driveshaft and made tests with it, and found it's still vibrating. From here I knew there was a problem elsewhere than the driveshaft and decided to change the rubber mounts at the nose of the transmission, and for the viscous coupling. I bought 10 new rubber mounts. It's at this point that I also found that one of the transmission mounts was not holding because the bolts threat were worn out, we tap the hole in the frame at the next size threat and bigger bolts and fixed that problem.

THE FINAL SOLUTION: Change all 10 rubber mounts (around 25$ each from VW). 4 at the transmission, and 6 at the viscous coupling. The rubber mounts are difficult to "diagnose" as it is not apparent to see if they lost their usefulness. Unfortunately, the big plastic washers that goes around the rubber mounts desintegrated as soon the old rubber mounts came off. Bought new big plastic washers. Result: Yes there is a god indeed, NO MORE VIBRATIONS!!! And that is without making the final laser alignment of the flanges.

So the moral of the story, learn from me and save your cash.

1- Do the "inner bronze bushing test" before alignement because no driveshaft balancing shop can find out if the inner bushing is ok with the driveshaft out of the van, you need your weight to find out. Unless it is soo loose that it is that easy to diagnose. It is hard to exercice the equivalent of your weight to feel the gap if the inner bushing is loose, by just holding the flange with your hands. And it is impossible to mesure the inner bronze bushing from the outside. Remember, there is two bronze bushings to hold the "male" flange part. The tube part is the female (you will understand when you'll remove the rubber mount). The outside bronze bushing one is easy to mesure and replace, but the inner one you have to "open" the driveshaft (separate the tube from the u-joint flange at the weld), replace the inner bronze bushing, then weld it back together. If I knew it from the begining, I would have bought a brand new driveshaft instead. Cheaper, believe me.

One more thing about driveshaft alignment shops, their equipement is made to rotate at approx a maximum of 1000 RPM, and the driveshaft vibrations for the syncro starts at approx 2500 RPM (for the 60-80 km/h or 40-50 MPH). They are limited with what they can do. To most of the shops, if it does not vibrate at those speeds it is ok. That is just the limit for them. High speed balancing is very rare, as I did not find one in montreal, it was actually somewhere in the south of the US that makes high speed alignment for BMW or something, and they were asking for an outraging price.

2- After balancing the driveshaft, if there is still vibrations, just change the damned rubber mounts for the transmission and viscous coupling. they are 120,000 miles used / 20 years old anyway. Make sure all mounts are secure to the chassis. Check if your tires were balanced recently (another cause of vibrations).

3- Then use the laser alignment tool if you really need it. I still did not do the final alignment, and still no vibrations (since Christmas 2008), and it is out of alignment by a couple inches!!! Those new rubber mounts really work! I am not saying that the laser alignment tool does not work. Remember I said I always keep and eye on the center rear view mirror? I just noticed this week a very very very small double vision in the mirror between 60 to 80 km/h. I will make that alignment pretty soon.

Good luck (I hope better than me)

Mon May 25, 2015 5:31 pm

The above post shows why shimming isn't the answer.
If you have compressed mounts that need replacing, shimming is not fixing the lack of durometer.

Yes the mounts are expensive, and not all are created equally.
I have a few sets of mounts..cost effective ones...that are not the right size for this application.
The mounts I use all have come from VW or Powerflex.

When the flange angles are off...the first place I start looking is at the mounts.

Mon May 25, 2015 6:34 pm

I replaced the mounts, both trans-axle and transmission with powerflex. Ya no kidding they are pricey, but I'll never have to redo them again.
The rear mounts were not in too bad of shape but the fronts were pretty mushed and were holding the diff at an off angle/slant...still didnt fix my vibration at all though.
I dont think the shims are the answer either...I am going to try them to see if things change at all for better or worse. Just going down the road of deduction I guess

Tue May 26, 2015 5:49 am

insyncro wrote: Zeitgeist 13 wrote: What is it about the T3 Syncro driveline design that contributes to vibrations? I've been a longtime member on MB and Audi sites, and don't remember ever hearing of problems with their shafts...ever. A center slip yoke with bearing support seems like one crucial difference that folks might consider as a design upgrade. I've driven exactly one Syncro, and it had a nasty vibration that I've not revisited and resolved

Quattro Syncro has the center bearing carrier mounted with a two piece driveshaft from the donor vehicle.
Smooth as silk and the flange angles would raise a few eyebrows for sure.

Zeit'- I've wondered about this same question many times. Almost every syncro van I've driven has had some degree of that typical syncro buzz vibration at a given speed. I've had probably hundreds of Audi quattros and 4mot Passats in a out of my shop from when they were nearly new to 300K+ miles on them and I've only had to service the drive shaft on exactly one of them. The rest have always been vibration free.
My Quattrosyncro van, as Dylan has mentioned, not only has some strange looking flange angles, but also the engine/trans is shifted to one side about 1 3/4" while the front diff is centered in the van. I didn't use a laser or any fancy tools to line up the driveshaft center mount and the driveshaft was a used one with over 220k miles on it yet it has not a bit of vibration at any speed.

Andrew-