Shudder vibration like noise on overrun....

[Defendozer]

Hi all,

My 300tdi 110 has developed an awful shudder/vibration when backing of the throttle or slowing down etc, it sort of feels like its just underneath the seats somewhere although its hard to tell exactly..
I removed the rear propshaft and went for a quick spin which if anything made it worse, I then removed the front prop and went out again which made it all but disappear so I'm thinking it has got to be something forward of the front output on the TC.
So what could cause it? All the uni's are in good condition. Only thing I can think of is that it has caster correction bushes fitted which I only put in because I happened to be given them by a mate although it does have a mild lift fitted (40mm) so I thought they wouldn't hurt. Oh and the front prop is out of phase by 45 degrees which is the manual spec I believe?..
What do you think?

Cheers

[Loubrey]

Certainly don't need the caster correction bushes for a less than 50mm lift. As good a place to start as any looking for the shutter, unlikely as it might be.

You sure your front diff is 100%...? Defenders are famous for noise transmission and problems are very often nowhere near where you think the sound comes from. You're certain to get more advice, but symptoms sound very much like diff lash gone wrong, especially if the shudder is very prominent through the steering.

Cheers,

Lou

[Defendozer]

Certainly don't need the caster correction bushes for a less than 50mm lift. As good a place to start as any looking for the shutter, unlikely as it might be.

You sure your front diff is 100%...? Defenders are famous for noise transmission and problems are very often nowhere near where you think the sound comes from. You're certain to get more advice, but symptoms sound very much like diff lash gone wrong, especially if the shudder is very prominent through the steering.

Cheers,

Lou

Thanks Loubrey, just so happens I have new poly radius arm bushes here that came with a bush kit so I'll fit them and see what happens.

I'm not sure at all if the front diff is 100%.. And actually that reminds me, there is quite bad backlash when depressing the clutch to change gears so maybe it is the diff would you say?

And its not really through the steering at all more a grinding vibration I guess you could say that definitely seems to be in the transmission and somewhere at the front end based on my diagnostics so far.

[wrinklearthur]

Are you heading to Hobart anytime soon?

If you swing by into my place and as a fellow 300 TDi Defender owner we can compare notes and we should be able to find the source of that problem.

[Defendozer]

Thanks for the offer mate that would be great, just so happens I will be making a few trips down to Hobart over the next couple of months for meetings, not sure exactly when yet but would it work if I send you a pm a couple of weeks ahead to let you know?...

In the mean time I will get to fitting the radius arm bushes to see if they make any difference...

[Defendozer]

So I've been doing some research and it got me pondering.. If the front diff has some problem that is causing the shuddering, could it also be the cause of backlash? Reason I ask is that I was reading in another thread that a worn centre diff can cause excessive backlash, is that possible? The TC is leaking in the usual spot between it and the gearbox so need to pull it off at some stage anyway and I was just thinking if the CD is possibly the cause of "some" backlash it might be worthwhile rebuilding or replacing...

[DazzaTD5]

Yes a worn centre diff will cause back lash quite badly, the wear will be in the shims behind the side gears. New shims and two new selective thrust washers will fix that. The other big item that causes back lash is worn axle splines / drive flanges.

This is also the biggest cause of back lash on new puma engine Defenders, apart from the gearbox clunk / rattle which is a faulty clutch assembly. This can occur from that 70K onwards.

Regards
Daz

P.S the vibration:
is there excessive play on the front output flange on the transfer case? (yes there will be some play).
Any play in the diff flange?
Are you sure the front prop shaft is good?

[Defendozer]

Front prop shaft is relatively new (150k roughly from memory), the splines still have the blue coating on them and have very little play so shouldn't be an issue I would think.. Uni's are ok as well.

Yes there is free play in both flangers however I'm not certain what is considered as "to much" so I'll take the prop off again after work and see if I can roughly measure how much they are turning and report back.

[GoldCloverLeaf]

Putting castor correction bushes in with minimal lift could be causing the vibration as it increases the operating angle of the propshaft at the transfer case end.

When i put castor corrected arms in, i had to upgrade to a double cardon front prop as the angle was too great, causing a vibration...

I would try replacing with normal bushes and see how it goes.

[Defendozer]

Cheers mate thanks for the tip, I've already got new bushes ready to go so come the weekend that'll be the first job on my list to do.
I'll give her a run and see what happens..