3B Diff output flanges vertical play

[gmac78]

Yeh I guess the last resort is to send the prop away for refurbishing and balancing, even although it already has a new UJ & centre bearing, perhaps I'd be better off replacing the CV joints then sending away for balancing. Does anyone have the correct part number for these CV's, I've read somewhere they are Ford Scorpio rear inner CV's, not sure if that's correct though?

The thing is with this vibration it just kind off started one day out of the blue when I hadn't even been working on the car, so I'm guessing my propshaft was fine up to that point as hadn't noticed any excess vibes. Or perhaps it was slightly out of aline from the previous centre bearing fitment and it got worse over time prematurely wearing the CV joints? I'm just not sure!!

[Bowie69]

Ah, different situation here, I have three new joints and a new bearing on mine!

I have a spare prop, tempted to swap it in to rule it in/out.

Joints are specced in the propshaft rebuild thread on here.

[Bowie69]

These are the boots:

https://www.ebay.co.uk/itm/GKN-Race-....m46890.l49286

Joints are an SKF number:

https://www.ebay.co.uk/itm/Joint-Kit....m46890.l49286

Don't think mine came with boots, I forget now....

[gmac78]

Nice one, cheers for the links. What speeds are you noticing the vibration at? I've noticed over the last few days of testing that I get a vibration around 25-45 and then around 90-100. The higher speed vibration goes completely I think depending on what position I have the propshaft installed on either gearbox or diff flanges. With the prop installed in the least vibration position the 90-100mph vibration is gone, but the lower speed vibration is still there. No matter what position I try the prop flanges in I can't get rid off it. This may very well be because the two halves of the prop or not in the exact position they should. It a lot of work to alter this on a trial and error basis. However part of me wants to keep trying for experimental purposes.

[Bowie69]

25-35 mph, don't often get to 90 round here

Think I'll first try moving the centre bearing, see if that helps, then swap the prop out with a hope that it cures it.

[s2driveruk]

Just thinking about this some more, i guess
1. Are you sure the differential to driveshaft cups are tight? They have a single stretch bolt that is not torqued higher than 6-8nm from memory
2. The only other things could be a failing roller bearing, one each side or maybe a failure of a shim/washer which is allowing some movement but there would be evidence of that if you drained the oil i expect.
3. Have you fitted the cork gaskets incorrectly and they are causing the prop not to sit flush with the diff cup and that is causing a vibration.

here is the family album with the exploded view...2 & 3 are the taper bearings and skf do them.
https://audi.7zap.com/en/rdw/audi+co.../525-525030/#3

[gmac78]

Good shout with these suggestions, here are my observations-

1. I did tighten the driveshaft cups, not using a torque wrench but adequately tight, however reused the old bolts. The vibration was present using the old diff as well as new so don't think the issue lies here.

2. The vibration was the same using both diffs so don't think there was anything internally wrong with the original

3. On fitting the new inner CV joints I did notice that the face that mates against the cups did not have a raised lip/recess on it like the old ones where the gasket would locate, so in theory one could tighten the CV up squashing one side of the gasket more than the other. Due to the lip/recess on the originals this was not possible as the gasket sat in a slight groove if you like. This thought did cross my mind but because I was aware of the lack of recess on the new CV's so I nipped them up square before tightening and then tightened in stages so hopefully sitting even. Again this vibration was present before any of the these components were touched.

One thing that sprung to mind last night whilst pondering over this in bed, was when I first started to look at this last week I noticed that one of the propshaft UJ cups had come slightly loose and was allowing some movement in the UJ (They're held in by circlips on the 3B) I tapped this up snug again but perhaps the UJ is not sitting central in the yokes. Also I had the UJ apart twice since then as clocked the propshafts 180 deg so possible the vibration is coming from there.

In the past when fitting these UJ's I've simply snugged up the cups either side and refitted the circlips and had no vibrations issues. I'll need to double check if it's sitting central in the yoke. I've seen other people using coins to measure how much the UJ cups are recessed by, however my thinking was when they become tight in the yoke that is them located, perhaps I need to pay more attention to if they are actually sitting even on both sides??

Hmmmm.........

[SteveH]

Just my tuppence worth. I bought a new centre bearing and CV's and sent my prop off to be shortened and balanced.The propshaft company called me when they had the items and told me that the CV's were wrong and my original items would be better than fitting the new ones. After a bit of digging they located the correct CV's and I opted to have them supply and fit. These were £80 a pop rather than £30 each. I can take a note of the numbers from them if that helps? I also have the Ford Scorpio joint and it's too large to fit the gearbox output flange. The incorrect CV's fitted but were a little loose on the splines. I would have thought they were fine and they are mentioned on lots of threads on here.

[SteveH]

Oh and my car never had issues with vibration until I changed the exhaust and other items like engine mounts. Could it be something other than your prop?