Time for a gearbox rebuild

['The Gaffer']

After all the work replacing the diff, propshaft and driveshafts on my Toniq, I still have a noise that I'm not happy with. Both Dave from Phil Jones Engine Developments came out to inspect their diff rebuild, and Nigel from Chards came out to inspect his prop work. Neither found any problems with their work even after some very fine tuning. A credit to both companies for the support they gave.

What now appears to be happening is the noise is coming from the gearbox but being transferred down the prop and into the diff mount making the chassis act like a sound box

How such a small sound can be amplified so much is still a mystery, but it is the same sound. Play both vids at the same time and you can hear the pattern.


Sound starts here (Prop has been removed in this video)

Amplified here

Ah well, more money to spend

[Furore Phil]

How can the sound travel down the prop ? it's made to move with sliding couplings, or at least rubber ones, so you shouldn't get much in the way of sound transfer.

It doesn't sound very repetative, more random, but that could be due to the idle. What happens to the sound when you rev ? Does it dissapear when you press the clutch ?

You can gurantee it's something simple. Have you checked the glove box for marbles 

Had a weird pop that used to appear in an old car of mine. allways appeared 5-10 mins after setting off. Turned out to be from a plastic bottle of water on the back seat ! as the car warmed up the air was expanding in the bottle and popping out a dent in it's side !

['The Gaffer']

I wish I could have a definitive answer Phil, just for my own sanity if nothing else.

There simply is nothing else to check, and believe me a lot of people have tried to trace this noise.

The prop is in effect a hollow tube that will carry sound, how its so loud at the other end is still mind boggling, but apparently is very possible

If not in gear no problem at all.

[Bulldog Bri]

I had a nosiy tappet on an old car many years ago and the way the mechanic found which one it was, was to put the end of a screwdriver on each in turn while the engine was running and the handle end to his ear (thumb over the end just to protect his ear a bit) and he could hear very clearly which one was making the nosie. Just wondering if this technique could be used here...

['The Gaffer']

I had a nosiy tappet on an old car many years ago and the way the mechanic found which one it was, was to put the end of a screwdriver on each in turn while the engine was running and the handle end to his ear (thumb over the end just to protect his ear a bit) and he could hear very clearly which one was making the nosie. Just wondering if this technique could be used here...

Bri, I have guys going over every inch of the car with proper mechanics stethoscopes. It's a really hard noise to track and considering I've now fitted two diffs and the same noise is present, the prop joints and bearings are smooth and tight, it doesn't really leave much .

It has been suggested that maybe the lay shaft is clattering in the gearbox.

[Furore Phil]

err dumb suggestion probably.... but have you been removing rivets by drilling them out ? could it possibly be debris in one of the tubes bouncing around ?

Guess it's one of those problems where everyone and his brother has a suggestion.

['The Gaffer']

err dumb suggestion probably.... but have you been removing rivets by drilling them out ? could it possibly be debris in one of the tubes bouncing around ?

Guess it's one of those problems where everyone and his brother has a suggestion.

Nice idea Phil but no rivets drilled, apart from that the noise is just too loud. You forgot to mention the brothers dog too

[gingerpaul]

I'd be surprised if that was gearbox related, although that's not to say it isn't.

Are your engine mounts and diff mounts ok? Are the bolts tight? Have the bushes / mounts perished / broken / come away?

Is the water pump impeller in one piece and still attached to the shaft?

Is everything relating to the clutch tight / properly located?

Is the anything in the transmission tunnel rubbing on the prop shaft / ujs?

Do you have a reverse box? If so are the mounts ok on that?

['The Gaffer']

I'd be surprised if that was gearbox related, although that's not to say it isn't.

Are your engine mounts and diff mounts ok? Are the bolts tight? Have the bushes / mounts perished / broken / come away?Diff mounts and centre bearing mounts are good, engine mount bushes are a little perished but no sound coming from them.

Is the water pump impeller in one piece and still attached to the shaft? Interesting, havent checked that, will take a look with a Fireblade mechanic soon

Is everything relating to the clutch tight / properly located? That has not been checked yet, really need a mechanic with Fireblade experience.

Is the anything in the transmission tunnel rubbing on the prop shaft / ujs? All is clear

Do you have a reverse box? If so are the mounts ok on that? No reverse box

This sound is really a mystery but stethoscopes are pointing towards the gearbox

[gingerpaul]

Does it only make those noises in gear? What about when it's in neutral? What happens in and out of gear with the clutch disengaged?

['The Gaffer']

Does it only make those noises in gear? What about when it's in neutral? What happens in and out of gear with the clutch disengaged?

Noise is only there when in gear (Any gear) if clutch is pressed in noise disappears which thinking about it rules out the water pump too.

Intensity does vary with revs though, louder at times especially at lower revs.

[gingerpaul]

Aha, ok. What happens if you disconnect the propshaft from the end of the gearbox?

['The Gaffer']

Aha, ok. What happens if you disconnect the propshaft from the end of the gearbox?

The top video is with the propshaft removed, sorry I should have mentioned that. The wheel you see spinning is the prop adaptor plate.

[gingerpaul]

I see. I'm not very clued up on bike engines.   

You're running out of options then! What about the big end and crank bolts? If one of those was lose would that cause that noise? I'd have thought that clatter would be a lot louder if it was.

The revised list then:

-gearbox
-clutch
-big end and crank being lose somewhere

Hmm.... 

['The Gaffer']

OK stop the press..

I have had a long chat with Andy at AB Performance (Bike engine racing guru) today and it appears the noises I am hearing are quite normal for a bike engined car with the wheels off the ground

Apparently, because of the nature of the bike 'dog type' gearbox there is naturally a lot of backlash, and as the prop and wheels are acting like a flywheel, the gears are always slightly out of sync with the prop. This highlights the slack as the engine is not running at a perfect steady speed - so the whole transmission cant run in perfect sync.

This causes the backlash to 'slap' from one side to the other causing the noise. (This is taken up by the chain on a bike so no noises)

Here is the backlash that is never taken up unless the engine is under load.

It is also very common for the noise to travel and get amplified by the prop and chassis acting like a soundbox. Before I even had the chance to describe the sound, he said "Like hitting the diff and prop with a hammer?quot; and "Sounding like a bell clanging?quot;

I even showed him my youtube vids which he confirmed as being quite normal.

He did suggest I got some kind of cushdrive on the prop to absorb some of the clunks etc. This has already been done and I have opted for a tube over tube prop (One tube over the other seperated by rubber that the power is transfered through more smoothly)

So bottom line, nothing to worry about it seems but thanks for the suggestions guys.

[Richard]

That has to be a good outcome !

[gingerpaul]

How about that! Well I think it's fair to say I wouldn't have thought of that. Good news!

[Hairy Santa]

WOW that is some backlash, thats why it sounded like layshaft chatter, are you sure that much is normal

do you have a manual on the engine and box, could I have a look at it if you have

Glad you have found the cause - just have to work on how to muffle it a bit now then

Got the solution in one, convert to chain drive with a large sprung rubbing tensioner -- now that would cure it    or even put a V8 lump and box in - ye thats the way to go

All the best

Pete

['The Gaffer']

WOW that is some backlash, thats why it sounded like layshaft chatter, are you sure that much is normal

do you have a manual on the engine and box, could I have a look at it if you have

Glad you have found the cause - just have to work on how to muffle it a bit now then

Got the solution in one, convert to chain drive with a large sprung rubbing tensioner -- now that would cure it    or even put a V8 lump and box in - ye thats the way to go

All the best

Pete

Yep that is the amount of backlash typical of this engine, I dont have a manual but have been busy trying to download one from somewhere.

My new tube in tube prop should help quite a bit when its built.

Be a pretty long chain and I'm not sure I'd like that trashing around next to my legs

[Hairy Santa]

Yep that is the amount of backlash typical of this engine, I dont have a manual but have been busy trying to download one from somewhere.

My new tube in tube prop should help quite a bit when its built.

Be a pretty long chain and I'm not sure I'd like that trashing around next to my legs

wouldn't be my legs I'd be worried about


that bloke on Penine sands back in the 20-30s thought it was alright until it took his head off - from memory the car was named Babes

['The Gaffer']

Yeah that was nasty 1927 Godfrey Parry-Thomas in Babs. He was half decapitated by a flailing chain


Hope my car is a little more technically advanced

[gingerpaul]

Yeah that was nasty 1927 Godfrey Parry-Thomas in Babs. He was half decapitated by a flailing chain


Hope my car is a little more technically advanced

I saw that car go round Goodwood a couple of years ago. They had dug it up and restored it.