Noise under load

[Padster]

Dear all a request for your ideas on a niose under load problem.

My friend and I bought a 1961 2 door last autumn. No MOT 61k one owner, and their handyman, whose garden it had been laid up in for 6yrs in a tent. Trailered away. It started drove into our garage in kangaroo fashion, the pedals had fused with corrosion.

Much, much TLC later it emerged. Front and rear suspension off new rear axle casing, corrosion had the first. Poly bushes all round. New brakes, wheel cylinders, lines and master cylinder fitted. New hoses and water pump, carb serviced. A little bit of welding not masses. The gearbox has been out new mounts fitted nothing untoward seen cleaned up and replaced. It is a 1098 box on the original 948 engine. The clutch diameter was measured and we think its a 948.

Passed MOT with much appreciative interest from mechanic. Weve done 350 miles she pulls well. Changes gear fine doesnt jump out of gear.

BUT under load there is a loud intrusive grrrrrrrr that comes and goes almost as the car rises and falls worse when warm. There is some vibration through the floor that accompanies it. Sounds to me like its coming from the box but could be engine.

So my friend has had the gearbox out this week stripped to component parts appears in good condition. Hes seen a few before so knows what condition looks like. Sump off bearing shells off all lokks fine.

He we are going to put it back together stumped as to the noise.

PS Middle of June we are setting off in her on a 5500 mile european rally 23 countries in 23 days with 17 other vehicles,so we could do with this sorting. "http://www.windy500.co.uk/" . Any suggestions? Thanks

[frame][/frame]

[simmitc]

Initial thoughts: Exhaust knocking on the body? Does it have a standard air filter, and is the housing complete - missing bits can give a throaty roar. Is the gearbox steady cable just slightly slack - it should NOT be taught, just meant to stop the box sliding forward under heavy braking. The new engine mounts currently available tend to be harder than they should be, and therefore transmit more vibration.

[beero]

"loud intrusive grrrrrrrr that comes and goes almost as the car rises and falls"

Do you mean it varies as you go up and down on an uneven road? If so it could be the uj's on the propshaft.

[bmcecosse]

Sure it's not pinking (or even detonation) under load? Retard the timing to see if it goes away... But the other suggestions are all possible too.

[Padster]

Thanks all.
Its not the exhaust altogether too mechanical a sound a grrrr....rrrrr....rind. We will ensure gearbox steady is slack as it goes back in. We discussed the idea of it being down too harder new gearbox mounts. Thought it may influence vibration but not the grrrrrr unless they are slightly the wrong size.

Not pinking again far too mechanical.

UJs sound an interesting suggestion. They were looked over when box and axle were out. It can still make noise on the flatest roads. But yes I mean the rise and fall of an uneven road surface can influence the intensity of the grrrrrr.

[DAVIDMCCULLOUGH]

For a long time I had what I thought was a noisey gearbox, had the box out and done up only for the noise to be the same. Turned out the diff was the issue, noises can be referred on a car quite easily. What about posting up a link to you tube with a recording of the noise?

[Padster]

UJ's were greased up and look fine. As she needed a new rear axle casing over the winter internals of dif have been out and TLC applied. Unfortunately we dont know what it sounded like when laid up 6 yrs ago.

Its going to take few days and a delivery of gaskets to reassamble box and sump so if its still there next week then a recording we will make. Thanks

[simmitc]

Jack up each wheel in turn and spin it to see if you get any noise. With all four wheels on the ground, bounce each corner and check for the noise. Chock the fron wheels, jack the rear ones off the ground and run the engine in gear, listen for the noise. Am I understanding correctly that the noise does not occur if revved in neutral? Sorry, lots of questions, just trying to narrow down where to look...

[Padster]

I like the idea of running in gear with rear wheels off the ground listenning for the noise. Hadnt considered that.

The noise doesnt appear when rolling in neutral. Thanks

[JOWETTJAVELIN]

Perhaps it was laid up because of this noise? Can the last owner shed any light on the situation?

[IslipMinor]

If it's a 1098 gearbox with a 948 clutch, the 948 clutch is much thinner than the 1098, which means that the clutch release arm has to swivel forward much more and can bring the carbon thrust in contact with the gearbox primary (input) shaft - especially when disengaging the clutch. The 1098 gearbox front cover is different to the 948 (the pivot point is further away from the flywheel) and cannot be simply swapped and the hole pattern is different.

[Padster]

The layup was due to first owner being too old and gave her to the handyman gardenner who didnt drive her.

Ok Richard. Are you saying its not a 948 clutch because if it was it wouldnt work with a 1098 box or if it is still the 948 clutch it can work but is likely to be making the noise? Clutch action was Ok.

[mogbob]

" UJ's were greased up and looked fine "

Did you try rotating the UJs, hand held either side, twisting in opposite directions whilst the car was safely up on axle stands, feeling for any slack / movement ?
UJ noise is normally a pronounced " clonk" ,on take up of the power to the diff, than a " grrrr " but elmination of any contributary causes helps you to get to the route of the problem.
Bob

[Padster]

Should anyone ever be interested the noise was.....................big end bearings. Though the main bearings were fine big end bearings had warn through to the brass. Now replaced. For the first time when driving we can hear a healthy gearbox wine and hold a conversation. Theres a small grumble under load, but guess its the crank shaft that will have been running for a while with knackered bearings.

So June 14th we are off to Europe 5500miles in 23 days different country everyday. Whoopee [frame][/frame]

[bmcecosse]

Earlier you said 'sump off bearing shells all lokks (sic) fine'...... so how can we hope to help you with wrong information like that......??? New big end shells on a crank that is worn/was rattling (grinding you describe!) will barely last 500 miles - you will be mad to attempt 5500 miles like that........ I strongly urge you to fit an exchange crankshaft and a new oil pump, and an oil pressure gauge before you go anywhere...... I have also never seen worn big end shells, where at least the centre main shells (and crank centre main bearing) were not also badly worn...... Seriously - it would be crazy to take this engine on any sort of run as it stands now.

[irmscher]

i wouldn't take the car 50 miles if you want to do that kind of miles change the engine or rebuild the one you have good luck

[Padster]

Mmmm we thought about the crank aspect. Rest of bearings really were not bad, but renewed. Fitted a Smiths oil pressure guage when reassembled and are monitoring. If she needs a crank and ancillaries then so be it.

[ASL642]

Also check the oil in the diff.

[bmcecosse]

What's the oil pressure at 40 mph in top gear after a good long/hard run in the car?

[katy]

Did you check the clearance on the big end bearings after you replaced them?