knockin and juddering

Post by **shakey** » 22 Jun 2008, 15:25

Hi, been a while since my last post(or cry for help).My (westy 2.1 syncro with rear diff only) bus has a slight knocking(almost bell like) happening when i pull away in first especially if i am not giving the bus enough welly(dosen't happen all the time) and have noticed that after a reasonably long drive the bus feels like there is a handbrake on when you are parking or turning in full steering lock(got some juddering then too and engine stalled).
The tyres are good and pressure ok and the bus drives good on journeys.
Is this prop shaft or VC problems? or both?
Also is it normal to get a slight crunch when engaging 1st gear, again this dosen't happen all the time but i've heard this is common on syncros.

Thanks all

Post by **Russel** » 22 Jun 2008, 15:36

Bothe!

Post by **shakey** » 22 Jun 2008, 15:45

So its time for a visit to the garage, is this a big job?, i know its tough to say but is this gonna be expensive.

Post by **Mudlark** » 22 Jun 2008, 21:41

Rebuilt prop: take it off send it to somewhere up North (ask Aidan) and get it refurbished, gets sent back to you all made good and refit it. Not a difficult job; cost about £300 inclusive.

VC, do it while the props off; refurbed unit from anyone who has one costs about £450/£500; or get Aidan to fit a decoupler for you and keep your tight VC in; or get a new VC from Bernd Jeagar/other german dealer for about 750 Euros plus carriage. Again a job you can do yourself even if you aint that good with spanners; I should know I have done both

So at least £800 but its money well spent on any good syncro, will transform your driving pleasure and is likely to be recouped if you sell your van any time soon.

Post by **timtheenchanter** » 23 Jun 2008, 18:35

[quote="Mudlark"]or get a new VC from Bernd Jeagar/other german dealer for about 750 Euros plus carriage. Again a job you can do yourself even if you aint that good with spanners; I should know I have done both

An its still going strong.

Post by **shakey** » 23 Jun 2008, 20:29

Thanks for your replies. Thinking about the decoupler route. Any ideas how much to supply and fit?

Post by **Mudlark** » 23 Jun 2008, 23:35

Talk to Aidan about the decoupler, cant remeber what the total price was, but its not a cheap option.

Hi Tim; good to hear from you, hope all is well and that you are enjoying your van ?

Post by **HarryMann** » 24 Jun 2008, 10:01

Also is it normal to get a slight crunch when engaging 1st gear, again this dosen't happen all the time but i've heard this is common on syncros?

Nope, but into 2nd when cold, Yes. Change g/box oil can help to something more expensive. If its when you're changing down from 2nd , then that's a gearchange best left un-made if you can avoid it, if not, get the revs spot on first and change down slowly and methodically. See Wiki

Loud bell-ringing mode (rattling) propshaft as you pull away and revs drop (circa 1200~1400 rpm)... They do it!
Very often even with a perfect prop, in fact you can change props all day - can be worse on diesels. However, do take it off and throughly check the UJs for smoothness and lack of wear.

This bell-ringing is very different to driveline vibration that can shake the vehicle at a given road-speed, usually between 38 and 45 mph. This loud low speed rattling, which you can reproduce remarkably well by tapping the propshaft with a spanner right in the middle is not usually associated with worn UJs or balance problems - its just an organ-pipe resonance, excited by the power pulses from the engine. Its often ascribed to the sliding bushings in the prop and polybush plugs have been proposed as a fix - but results controversial! Aidan's propshaft bush article

A juddery clutch doesn't help either, but if its a 'rattler' then it'll do it whenever the engine is lugged down at those rpm.
Its not unknown to try turning the prop around, after you've checked it. Sound damping sheet material can be bonded on but has to be done very accurately and thoroughly fixed.

As far as road speed dependent driveline shake is concerned: Read carefully before spending a lot of money...
http://www.syncro.org/DriveShaft.htm

New GKN props can be had for £200 delivered. They're not the same as VW ones, but are made to measure (1277mm); they can also rattle just like VW ones.

The amount of drag when on full-lock is a matter of judgement and degree - don't expect none with a new VC, there will be some, Syncros have a very tight lock. Try to avoid the need for the last few degrees of lock on tarmac and never apply much power when near full-lock.

Post by **peasant** » 24 Jun 2008, 18:56

However, a cold VC should pass the following test:

From driving straight ahead, put the steering on full lock and drive into a circle in 1st gear on idle only.

If the engine stalls, the VC is definetly too tight.

Post by **HarryMann** » 24 Jun 2008, 19:25

What engine...?

What surface... ?

I am really cautious about condemning £500's worth of kit on any one test - if all else is OK... especially in this financial climate

Post by **shakey** » 25 Jun 2008, 08:45

Thanks for the comprehensive reply Harryman. I can put up with driveshaft knockin as long as i know its not damaging the gearbox etc. I think i will be going down the decoupler route and then treating the gearbox to an oil change.

Post by **HarryMann** » 25 Jun 2008, 11:18

I can put up with driveshaft knockin

Am working on this myself, but let's call it 'rattling' for now, knocking gives a slightly wrong impression (that's it's worn) when it's just getting a bit excited.
My GKN prop has got perfect UJs and no play whatsoever in the slider splines, though you could remove yours and at least check everything and thoroughly grease up the bushes.

Unfortunately it seems the SA Prop Polybush part is not available anymore, and Aidan says that 'it was only a partial solution'

Post by **syncroand101** » 25 Jun 2008, 12:21

Just had my Prop "re-UJ'd" and balanced by GKN at Leek for about £105 inc VAT and delivery.

Damn good value if you ask me.

Post by **HarryMann** » 25 Jun 2008, 12:24

'tis good value!

Now completey free of any trace of vibration under full power at 40~50 mph then Jake?

Post by **syncroand101** » 25 Jun 2008, 12:30

Yep. Doesn't ring either!

If I could afford a set of road tyres tt might actually be a peaceful ride