Strange Rattle noise...possibly prop area?

[sonic23]

This should maybe on Tech Q&A, but thought I'd throw it to the Syncro crowd first. I seem to still be having a strange pinging/rattle noise when I'm driving along. This started to occur about 6 weeks ago, and I have had to change the clutch about 2 weeks ago as a result of the friction plate disintegrating at Syncro P.

It occurs mostly at around 20-30 miles per hour, and more so when the foot is off the acclerator, though it also does occur when starting to accelerate.

I have done the usual non invasive tests for wheel bearings, CV joints and prop and everything seems to be fine.
I can't see anything lose, or fouling the prop.

The best way to describe the noise is like a roulette ball bouncing around on the wheel....though more metalic......It's very very hard to tell where it is coming from, though to me it sounds like it is middle to rear. I thought perhaps it might be a stone in the protection bars....but I've given them a good bang and can't hear anything moving.

So, I went out Today and tried to record the sound on the mobile, so apologies for the following poor quality clip on You Tube. I was basically in 3rd gear, decelerating, then put the foot back down on the accelerator. Times to listen for are 6-10 sec perdiod, it's very very faint rattle. Then much more noticeable as a rattle between 12-14 secs. Two single pings - one at 22 and one at 23, then another noticeable rattle between 31-32 secs.

http://www.youtube.com/watch?v=KhhcGfjRHEU

I'm a little mistified as to what this noise could be....any suggestions would be appreciated!

cheers,
Rich

[HarryMann]

Doesn't sound like propshaft to me, but then is the recording anything like the real sound -to you?

[sonic23]

Hi Clive - yes the rattle/ping in the clip is very much what I'm hearing. Quite distinct really. Especially the two pings at 22s and 23s..
Rich

[toomanytoys]

No loose bolts on prop and cv joints etc?

[jed the spread]

Give your back box a thud with the palm of your hand and see if its that maybe.

jed

[Mudlark]

Lots of connected pieces that resonate together throughout your drivetrain; I'd take the prop off and see if the noise goes away.

[sonic23]

Ahhhh.....Jed......you might be onto something.
I've just gone out and given it a good thump, and there is something definitely rattling in the back box.
On the side where it connects to the header, I can hear something inside it........a little like a ball bearing in a tin can.

I'll have to get someone else to drive it and then go lie in the back to see if i can confirm it as being the back box....I'd be happy if it was.

cheers folks.
Rich

[HarryMann]

I can hear something inside it........a little like a ball bearing in a tin can.

Could it perhaps be a ball bearing left in a tin can hidden in a locker somewhere, typical trick played on rookie Syncropendeees

Then, Mark has a good idea if not, eliminate the propshaft and drivetrain play - take it off.

[sonic23]

He he......so that's what you were doing under the van Clive.
I'll have a go at it this coming weekend and get back with the results!

Rich

[silverbullet]

I was hunting a strange, intermittent squeak which I thought I had traced to the Fan cowling - the top leg has fatigue fractured It turned out that it wasn't that at all.
When doing a headlamp swap to H4's, I found that one of the top outer retaining clips on the SA grille has cracked and gone walkabout. The pin was chafing on the lamp fitting and chattering according to crosswinds, road speed and surface etc.

[keeno]

Sounds suspiciously like the propshaft bearing behind the rubber donut. I had a very similar noise on my diesel syncro and was particularly present at low speed acceleration, mainly in second gear. It got so bad it sounded like a bell ringing at certain low speeds/frequencies. I replaced my bearing (a pig of a job - had to machine my own bush as I couldn't find one for sale anywhere...) and the noise disappeared. Bingo!

[HarryMann]

Sounds suspiciously like the propshaft bearing behind the rubber donut. I had a very similar noise on my diesel syncro and was particularly present at low speed acceleration, mainly in second gear. It got so bad it sounded like a bell ringing at certain low speeds/frequencies. I replaced my bearing (a pig of a job - had to machine my own bush as I couldn't find one for sale anywhere...) and the noise disappeared. Bingo!

Interesting... fancy machining any more up, thats a very common sound, esp on diesels

Aidan perhaps tried the SA nylon ones, quite a while ago now...

[keeno]

The problem with making bushes is that I am
pretty sure that 'one size won't fit all' as there was considerable wear on the male shaf that slides in to the bush. I had to resize that shaft and make a bush to suit. Maybe mine was a bit extreme in the wear department, but as it's the only one I have done, I can only speak from this experience. My advice would be to take the prop to a machine shop and have them make a bush and resize the shaft. That would be a gauranteed fix as opposed to a 'maybe' fix. You don't want to do the job twice as it's a swine!

[sonic23]

I got the prop off Today at lunch and took it for a drive.........The noise has gone.

So I've had a closer examination of the prop, and the UVJoint closest to the engine (so it's not the one next to the Rubber Donut, which is up front), is only moving in one axis. For example, it can be swiveled up and down, but not left and right. Tapping it with a Rubber hammer, in the stuck axis, will move it, but it is extremely stiff. Further, on closer inspection it looks like that the stiff joint has started to come apart, so I don't think it's a matter of lube!

Right....so do I get the whole prop refurb'd and if so where?
Or has anyone had a go with Syncrospares new props?

cheers
Rich

[Mudlark]

If I ever wanted another prop done i would go back to Chards in Bristol. They did one for my old Tri Star from scratch but it was not cheap. It was done in two parts with a sliding spline and a rubber cushion sleeve inserted to add a bit of give.

Otherwise there is a company up in the midlands that Aidan will remember the name of that will refurb the original for you quite reasonably I think.

If i recall correctly Chards workshop is open saturday mornings so it may be worth you popping in with it to discuss?