What is it about this Vibration Thing?

I originally joined the UK 300ZX forum because I found a recent thread about trying to cure a vibration which appeared to be down to the propshaft.

Many hours in front of the PC and hours under the car later (this is a lie - I may be able to find letters on a keyboard but am grossly incompetent with mechanical and electrical trickery. I leave that to others!) it became clear that:

1) everyone gets this vibration sooner or later
2) many forum posters have a lot of experience with this
3) you don't necessarily need to replace the whole (v expensive) kit and kaboodle to stop (as Senna said) your beautiful 300ZX feeling like a 320bhp washing machine.

Disclaimer: I am not technically qualified so if you take any action based on this information, you do so at your own risk. I accept no responsibility for the authenticity or validity of the items or articles linked from on this website.

The story starts here...

I bought my 1989 300ZX TT 2+2 in August 1999.

At the very beginning, I noticed an intermittent vibration which appeared to be related to road speed. Not engine speed, road speed. It felt like there was a lump on one of the tyres.

drrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr and so on.

OK, I thought, new set of tyres, balance the wheels - that'll sort it.

Hmmm - bit better but nothing to write home about.

At the time, I had all my servicing done by the excellent Slough-based Nelson Mandela, so simply told them to fix the vibes.

They tried several times quoting heat shield vibrations amongst other stuff then hit a blank wall. They contacted Nissan Japan for advice and were told "change the prop shaft". Given that this was estimated (at the time) at £750 + VAT + labour, I thought ****. Let's try something else before doing that!

The Z-Club mag ran a letter from someone who had a similar sounding problem on a late 1991 UK Silver 300ZX TT. He pinpointed the problem to the UJs on the propshaft.

April 2001
I toddled off to the supplier mentioned in the letter with the result that:

Remove and Replace Prop, Supply / Fit UJs and Balance £195
Labour £85
VAT £49
Total £329

He'd forgotten I was coming so that got everything off to a good start. The vibe got better (less pronounced) but no major change.

Hmmm - what next?

I asked Mr Mandela to speak to Mr XXXXX to find out what had been done - no satisfactory response from either so put to one side for a bit.

February 2002
Register on www.300zx.co.uk - things are looking up. They seem to be able to talk professional b***ocks and have a larf at the same time.

Find the first relevant thread http://www.300zx.co.uk/forums/ubbforum/Forum6/HTML/000227.html

There are pages on pages of good stuff from a lot of good people. Some of the ones I understood (vaguely) are included:

Cookie first posted with a story about a bad centre bearing and clicking front u/j being cured by a 1 piece propshaft.
antleeds posts about his garage advice on tyre noise, his vibe starts at about 38 mph
Timmy_Turbo says his does it from cold but stops after a warm-up
Jack is the first to flag up the gearbox rear mount (partial solution for me)
Spinning has wise words of wisdom m8 - especially about why not to replace standard 2-piece with custom 1-piece

February 2002 and a bit
Colin did a test drive then put the car up on stands
Centre bearing is out of alignment
Propshaft not rotating in the centre

Cos recommends might be wheel-based

March 2002
Jack has more good recommends to track down cure
antleeds has yet more wise words about 2 piece vs 1 piece shafts - and has good reports about a place in Bradford
I followed the forum suggestions: wheels off check, prod the gearbox mount etc.

Colin from V-Tech had discussed this with a prop-shaft place from Luton and they, too, said to do the gearbox mount first.

So I ordered one from www.japarts.co.uk £48.31 + VAT from J-land.

Warning: it looks easy to get to but if you miss the turn there is no easy way to get back without a guided tour of Hendon or somewhere. And when you get there, nowhere to park either (well there is, but it is very crowded indeed.) My advice? I wish I had taken their offer of next day delivery but that would have cancelled out the saving made on this one small part. OTOH I would have had 2 hours of my life back!

Fri 22 March 2002
Colin came round and fitted the new one. Couple of hours, tops.

There is a marked (positive) difference but still not perfect. The idea is to have a few days trundling around to quantify the improvement and then decide what to do next.

29 March 2002
Right then. While under the car, Colin noticed a hole in the rear exhaust so I now have a little organising to do. If the rear bit of the exhaust needs dropping, then might as well do the centre bearing and maybe prop at same time.

Well, off to the Forum meet in Solihull on Saturday (good excuse for a long blast) so let's see what the boys have to say.

What Next?
as far as I can tell from the excellent advice in this forum, the checklist looks like:

wheels off check done Mar 02
rear gearbox mount (Jack) done Mar 02
centre bearing to do
propshaft do I trust the previous one or do it again to be on the safe side?
dunno yet - watch this space!

In view of his happy experience, I am very tempted to follow antleeds to those chaps in Bradford....