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MG Midget and Sprite Technical - Where's that whine?!?!

Hey all,

I have been going round in circles in my head trying to work out which part of the transmission is whining at me!!

So it's a whine, noticeable around 40mph and above. Considerably louder when power is applied through transmission, depressing clutch reduces noise considerably and instantly but so does letting off the accelerator. Pitch changes relative to revs I believe rather than gears.

Please bear in mind this is a modified 1500 midget with performance exhaust and twin 40's so it's not a quiet atmosphere inside with a hard top on, therefore it is quite difficult to hear any whines off power distinctly enough to pinpoint it.

The conclusion I keep coming back to is that its the diff, but am I completely wrong and it's clearly the gearbox? (a type 9 by the way), or obviously a wheel bearing? I'm sure of the UJ's as they were new on the 5 speed propshaft that has now done less than 1000 miles.

As always any help apreciated

Dave
D Prince

Dave -

I've been getting a bit of a whine from my diff for years; as you described, it occurs under acceleration, and comes and goes at a certain rev range.

Come to think of it, I don't remember hearing it for a while. Hmmm...

-:G:-
Gryf Ketcherside

Hi Gryf

I'd like to say this was one of those normal midget clunks, whirs, creaks and pops that lets you know everythings going nicely, unfortunately it's more of a scream at higher revs which is enough to put you off any "spirited" driving at all!!

Dave
D Prince

leak in the intake system somewhere? as in air is being sucked in ... maybe a loose or damaged vacume line/vacume port. after all it only does it under load...so I wouldnt think its a gear box or diff.

any problems with over heating

Prop
Prop

Dave

I'd check/top-up gearbox and back axle with correct grade of oil (change if not sure) and then have another listen.

A
Anthony Cutler

Dave: Do you recall what type of gear oil you placed in the type 9 gearbox? there seems to be some varying opinions on the subject. On the other hand, it's difficult to imagine even the wrong gear oil would cause problems with less than 1,000 miles on the box. I'm assuming it was a recon box...

R
Richard 1979 1500

If it whines less in 4th gear then its the layshaft.
"THE" type 9 oil to use is Comma SX75W-90 semi synth.
Tim
Tim Dalton


Sounds very much like the whine I was getting- only when I was on the throttle, and only above about 40mph. I Couldn't decide if it was from the Diff or gearbox but decided to try diff first. When I took it out to investigate, one of the the phenolic washers behind the sun gears had completely crumbled, and the other was very thin.

It's a fair bit of work to replace them - by the time you've removed the diff, get the crosspin out, replace the washers and put it all back together - but they only cost a couple of quid, and it cured my problem. I replaced the shell washers behind the planet gears at the same time.

Hope you get it sorted soon,
Mark
MarkH1

I get a lot of whining - but it seems to come mostly from the passenger seat!
Chris H (1970 Midget 1275)

That's interesting, Chris.

I get a lot of whining in the TypeR, but less in the Midget; I think the extra back-ground noise-level in the Midget helps in this respect.

A
Anthony Cutler

Hi Prop

No issues with overheating (any more!! A different engine and a lot of £££'s ago for that but let's not go there!)Intake system seems free of air leaks, a spray of carb cleaner isn't making the engine pick up when sprayed around suspect areas.

Both diff and gearbox have correct weight oils to correct levels, only refilled approx 4 weeks ago and still at correct level.

I changed the rear bearings just in case but to no effect on the whine. I did however notice quite a lot of lash when changing the direction of rotation of the wheel when changing the bearings, I know that there should be some movement here but it does seem to be excessive!

I guess unless anyone knows of any other tests I guess it's just replace and see, just 3.7 diffs and type 9's in good condition aren't cheap :(

Any help always well received.

Dave
D Prince

This thread was discussed between 22/06/2009 and 24/06/2009

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