rear end noise? Differential?

[pjstock]

My 1995 T4 Transporter Syncro was making horrible rear end noises.

we suspected the hanger bearings on the driveshaft but after a very long search and wait, once replaced, that was not the issue. The noise was back.

(I've been running it as a 2WD with the driveshaft removed all summer. The noise went away when the syncro DS was removed.)

so my dear Mechanic suspects the rear differential but he doesn't know VWs like this and so we have parted ways.

Before I speak to other mechanics, I thought I would ask here if anyone has any ideas.

I've been told the rear differential still spins even with the DS removed. but with the DS in place there is extra load on it and so that might result in the noise that isn't evident when the DS is removed.

WHY WOULD THAT BE - that the noise Only recurs when the DS is installed.??

I have been told to look for a rear differential rebuild kit but those are not popping up anywhere.

should I be trying to find just the bearings?
any suggestions of what I should be looking for and where?

Peter

[TDCTDI]

Remove the axles between the differential & the stub axles, if it still makes noise, you need wheel bearings.

Actually, I tried to walk you through this before. If the rear differential doesn’t make noise with the drive shaft out then it’s not the differential. Disassemble, inspect, grease, & reassemble the CV joints on the REMOVED driveshaft.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[pjstock]

thank you.
so you are saying ignore the differential. The noise MUST still be coming from the driveshaft, just not from the hanger bearings?

I must have misunderstood you before about CVs. (I thought they were part of the axles, near the wheels.)

do I understand there are CVs in the driveshaft? (and forgive me - I am just trying to be go between between you all and a bunch of mechanics who don't seem interested in learning about these things, these era vans.)

if that is correct (I am looking at the CVs of the driveshaft itself) what are they? A and B in the attached photo?

[TDCTDI]

Yes, A, B, & possibly C (Maybe even D.) are CV (constant velocity) joints. Each of these joints are comprised of an inner race, an outer race, six ball bearings & a retaining cage. They are very simple yet fit together in a specific order to work properly. They are lubricated with a special grease that needs to be replaced occasionally & the joints themselves can wear if the grease is allowed to dry up or, in the case of thes joints, they have a tendency to “index” due to the fact that they don’t typically get used like they’re designed to due to fact that they’re in a fixed position. When this “indexing” happens, the CV joint will lock in position under load & cause the driveshaft to “rumble”, vibrate, or even knock depending on the severity of misalignment.

Here’s what they look like, I have marked the inner & outer races & cage for ease of reassembly.

And here’s what some minor pitting looks like on an outer race.

If, when you get yours apart, you find that the CVs are worn or pitted excessively, I have found that VW seem to only use one particular CV joint in all of their center driveshaft applications which happens to be a common, easily accessible part.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[TDCTDI]

While any one of them could be the culprit, look at the one that might be closest to the exhaust system as this tends to dry out the grease the fastest.

The grease tends to get runny as it breaks down or it can get a waxy consistency as it dries out. If you decide to service them yourself, just be aware that the proper molybdenum based grease has a high lead content & will permanently stain anything it comes in contact with.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.