Strange vibration problem

Sep 18, 2012 14 Replies

In preparation for possibly taking the Alfa 75 to Austria in a couple of weeks, I've been running around in it this week to iron out any issues (it has been in my lockup for 12 months unused).



I've come across a really odd problem - the car is fine when driving around and if I apply the brakes for short periods - but when I'm in traffic, using the brakes a lot more, I then get a vibration in the drive train when we start moving again.



This then wears off once I've done a few hundred meters and is particularly noticable when I come off the throttle.



I have absolutely no idea why this would happen, as the brakes don't appear to be binding (I can push the car around without too much effort).



As they're inboard rear discs, they're a PITA to get to, but obviously this is a bit of an issue - and my mechanic is on holiday.



I plan to empty a large dose of brake cleaner onto the rear callipers tomorrow - so that'll hopefully clear things up - but does anyone have any idea what might be going on?


Just doused them and took it for a run - a few miles urban, a few miles dual carriage way and roundabouts.

Can't replicate the issue, but it does feel like the brakes were dragging and they've been freed off.

I'll drive it to Birmingham and back over the next couple of days to see what happens.

If that doesn't fix it, we're taking the MX5 on holiday with us.

Oh, Arse.

It appears to be an issue with the clutch - it came back this morning, but I'd barely used the brakes at all.

For those who don't know, the clutch is at the back, in front of the gearbox / diff, so it's hard to make a diagnosis when it could be either clutch or brake related.

Very, very odd.

Wouldn't have thought so - the box has been out and rebuilt less than

15k miles ago.

I suspect it's a prop. bearing somewhere - there's a central bearing to support the prop. which sometimes gives up the ghost - although it does feel like it's coming from further back.

This issue sounds like what we used to call [1] clutch judder. The prime causes of it were oil on the clutch plate, os a shagged engine or gearbox mounting.

Steve

[1] OK, I'm showing my age again, and maybe they still call it that, I'm out of touch nowadays. You don't hear about it much lately though.

Doubt it's the clutch - but it seems you're probably right about the mount, as someone else says the same.

Hopefully it's something my mechanic can sort in an afternoon.

lighter fluid and a match will fix it.

Genius. Setting fire to an increasingly rare car, and the last 'real' Alfa Romeo model, just to fix a broken mount...

yebbut it will improve the value of the other 99 that are left.

Could be lack of use, some of the friction plate stuck to the plain plate and ripped out.

I moved a stack of Bantam clutch plates in the shed last week. All the corks were loose.

[...]

Soak 'em in oil overnight; they will be fine!

First clutch I ever dismantled was a Bantam one - in 1961...

Chris

They won't be fine. They are later type with wafers of veneer thin cork segments bonded on both sides a plain plate. Not the genuine vintage [1] slice of cork pushed though a punched hole. Having de-bonded they are done for. Superglue?

[1] Was pre 1959 when I was racing it in the 80's. They didn't want to take bikes from the Classic races. Now they have moved on and have races for the Bantam racing club's TZ125's hidden in a BSA Bantam crankcase.

Try a truck brake reliners.

Just get some new ones. Surflex £32.40

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Or I'm now all set for 4 plate metal to metal in a 3 plate basket, just need some slits to let the oil in, I have a 9 spring plate.
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Bet I could get 5 plates in a 4 plate basket.

I also have a MZ basket bolted to a Bantam clutch hub. Just need a round tuit and a small alloy saucepan welded on the outer cover. Though it's a bit big and heavy, may need some holes drilling in the basket fingers.

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