Everyone's under their van's today!!

Post by **jlk55** » 25 Mar 2006, 19:23

Saw on the forum, Ray has been busy today under his van. Your not the only one with the same problem Ray. When we got our single cab afew weeks ago, Jake came over and told us the rear diffs needed doing, and we have been soaking the unit ever since.
The day started lovely, spent the morning rubbing down our beetle ready to spray, then back at lunch to await Jake again, who once again was kind enough to come down and sort out the problem for us.
After our bacon sani's, we were all ready to get going, then of course, the heavens open up!!!
I know Jake was swimming tonight, but he was almost doing that under the van, he got so soaked !
We're slowly getting there thanks to Jake, appreciate it a lot, and thanks Claire for letting him out to play!
This guy really is a credit to the club.
John and Kate

Post by **futbus** » 25 Mar 2006, 22:22

I`ve been under mine today sorting a completely knackered turbo, but all sorted now apart from minor oil leak to look at during the week. Have to get some new oil return and supply hose for the turbo.

Still to do the brakes before next weekend as off the Coney Farm to learn what these vans can do.

What ever your upto just remember to have fun even when you want to throw in the towel, all the effort is worth it.

Post by **syncroandy** » 25 Mar 2006, 23:35

Yup, me too. Had the propshaft off to swap the worn bronze bush for a poly bush (from Gordon). No more ringing !

Post by **Ray** » 26 Mar 2006, 10:47

Andy I am still trying to get a prop poly bush but no success, where did you get yours from?
Ray
2,1 dj syncro
#0094

Post by **HarryMann** » 26 Mar 2006, 14:48

Aidan says it hasn't entirely stopped his ringing..

Have to get some new oil return and supply hose for the turbo.

Simon B has these in stock.

Post by **syncroandy** » 27 Mar 2006, 07:52

The polybush has reduced, but not stopped, the propshaft ringing. The slight vibe I had at 2400rpm in 2nd is still there too... Next thing to try is swap the shaft for a lower-mileage one and see if that sorts it, though TBH is not the highest priority.

Post by **Diamond Hell** » 27 Mar 2006, 08:12

The propshaft 'ring' is surely a characteristic of the Syncro and a nice reminder that you're driving a proper 4WD van.... or is someone going to tell me that every time the prop 'rings' something gets closer to breaking?

Post by **Hacksawbob** » 27 Mar 2006, 10:07

every time the prop 'rings'

God kills another kitten!

Post by **Diamond Hell** » 27 Mar 2006, 10:35

I didn't want to use that analogy, Bob, but couldn't think of anything better to replace it really....

Post by **andysimpson** » 27 Mar 2006, 20:56

If you want to get rid of the ringing and vibration get GKN to make you a propshaft with a damping tube, i can't remember the exact name. I have one and it is excellent. GKN seem very helpfull and the prices and good.

Post by **airhead** » 27 Mar 2006, 21:08

Ive never heard my prop doing this. Is it only on higher mileage vans?

I was under my van today too actually, just removing a battery tray to relocate it. The bolts holding it in place went out to the other side of the van. I hate working under the van. Bloody uncomfortable and dirt constantly falling in my eyes. Even with goggles theres always a clump that seems to find its way into your eye.

Post by **andysimpson** » 27 Mar 2006, 21:35

airhead wrote:Ive never heard my prop doing this. Is it only on higher mileage vans?

I was under my van today too actually, just removing a battery tray to relocate it. The bolts holding it in place went out to the other side of the van. I hate working under the van. Bloody uncomfortable and dirt constantly falling in my eyes. Even with goggles theres always a clump that seems to find its way into your eye.

I think alot of it is engine vibrations being amplified, some engines are smoother than others. Mine had a slight noise/vibration when i had a waterboxer, i changed to a 5 cylinder and had a really bad engine vibe at 3000rpm in any gear, if prop as removed there was no vibration. The GKN prop sorted it.

Post by **HarryMann** » 27 Mar 2006, 21:58

Bloody uncomfortable and dirt constantly falling in my eyes. Even with goggles theres always a clump that seems to find its way into your eye.

Get a full-face perspex strimmr style mask, about £12-£15, you need one anyway when grinding and wire brushing with an angle girnder, goggles are no good then.

think alot of it is engine vibrations being amplified

Andy, I bought a GKN prop, 24 hour delivery and only £175, but they didn't offer me a damper tube, dang! Great service, agree..

also agree it is the engine basic harmonics that act as a trigger, and I suspect, play in the diff backlash (who hasn't a sloppy diff

) and gears.
I'm about to try detuning it using self-adhenisve bitumastic patches

And the slightest play in an inner rear CVJ turns slight prop vibration into quite noticeable, looking at a damper attaching to front off-side of transaxle, a lug there looks quite inviting and about in the right spot.

Post by **airhead** » 27 Mar 2006, 23:56

SO why is the centre shaft so thick in a syncro? I mean its massive! Seems to me to be overkill.

Post by **HarryMann** » 28 Mar 2006, 01:36

Noo, Noo, not at all.

Its a thin-walled tube, and they're always like that to resist whirling yet add lightness! Don't forget the prop is going at pinion speed (engine speed with a 1:1 top gear) - not diff speed like the rear driveshafts, and is long and so prone to whirling.
The torque it has to carry is almost not a design consideration, the critical case being stiffness to raise the whirling speed above its highest in service speed (6,000 rpm?)
It also has to be made extremely accurately (concentricity mainly), to keep that whirling instabilty above design speed, as well as reduce vibration (two different criteria, but interrelated) e.g. if it were made badly off-centre, but balanced accurately, it might not vibrate, but its whirling speed would be brought down a lot, and if it did start whirling, you'd soon know about it

Bending stiffness goes up something like 3rd or 4th power of diameter, so you really score with diameter for stiffness, but a thin wall for lightness...* the rear drivshafts are short enough between the CVJs for whirling not to be a design consideration (propensity to whirl goes up with square of length). Double the length, the whirling speed can be 1/4. All well enough understood by design engineers, its where NVH comes in that can be a bit of a delicate matching up job. I'm sure they all came out the factory without prop vibrations, but over half shake a bit now, and some a lot. They obvisouly had constraints that they had to work around, and managed it - just about. A good example would be the famous swaying brdge across to the Tate gallery that had to be closed for a big engineering fixup - those sort of complex motions can catch designers out, without full dynamic testing, which seemed to occur very quickly in the final article

though I think if they had they a few aviation aerolasticity bods about, it would have been foreseen (wish I'd gone down that one day it was open and swaying like that, no strength danger, just a natural mode got excited

* so ally props, which some tout as performance replacements, are anything but, as ally is about 1/3 the stiffness, meaning that shaft has to be even larger diameter and thicker walled for damage resistance too.