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hippie dave

M20 Manual Gearbox stuck fast!

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Good afternoon, long time no post, hope we are all well.

 

I am attempting to replace the clutch on my 520i (5 speed, RHD, 1986.), as I suspect the release bearing is on its way out. 

I have removed absolutely everything necessary including prop, gearbox crossmember, linkage, hydraulics, and starter motor. 

I have dropped the back of the box down, and removed absolutely all the fastenings (lower plate, three 19mm-head bolts on dowels, two 17mm bolts and entire starter motor). 

With assistance, I have released the box from the three dowels and attempted to lever it off. 

It is just not budging. It'll lever about  6-8mm or so on a pair of crowbars, and doesn't appear to be being held by anything solid- i.e. there is a bit of "spring" to it.

It would appear to be held by the main shaft somehow. 

I fear that the release bearing has collapsed and is holding it in a circlip-like fashion. I don't mind breaking the bearing, but the possibility of collateral damage (or even having it crash down off the stands) from the required level of force is a concern. 

Has anyone come across this problem on an M20 car before and was this indeed it?

The bearing is completely inaccessible until engine and box are split. How the hell does one get around this problem without cutting into the bellhousing? 

 

Answers on a postcard (before I push this effing thing into the thames). 

Thanks all,

David

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Input shaft rusted/seized into the spigot bearing? I can see a 17mm bell housing bolt still fitted as well. I may well be that the release bearing has seized and chewed into the pressure plate - that's caused by a clutch hose that is blocked and acting as a one way valve. 

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A very annoying situation but one I've come across a few times. 

 

Are you sure all the bolts around the bell housing have been removed and are all intact? 

 

As stated above, It's possible that the release bearing is catching up on the gearbox input shaft nose cone or locked to the cover diaphragm spring for some reason. It is also possible that the spigot bearing has seized on the end of input shaft, Which I think more likely. If the latter you'll need to try to open the gap between engine and box as wide as possible to get a cranked spanner or 1/4 drive socket and unwind/remove the pressure plate bolts, not easy but possible if hex head bolts but if torx or allen style, much more difficult. 

 

Be sure there are no cover plates or sensors jamming the gearbox from removing easily. 

 

If it is the release bearing friction welded to the cover, then it's time to get medieval with it. It looks like the clutch arm locating arrangement is the usual spring type so I'd release that fixed end retaining clip to allow more movement to lever/wriggle the gearbox out.

 

I'd agree on the supporting of the car. Some added insurance would be very wise.

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1 hour ago, FIVE-OH said:

Are you sure all the bolts around the bell housing have been removed and are all intact? 

 Absolutely. 

Sorry that second picture is a bit misleading: I just replaced two of the bolts before before taking the picture- as I thought it would be unwise to leave it unsupported for potentially days on end.

I suspected the release bearing was on its way out, hence the clutch change. I was getting a moderately serious vibration through the clutch pedal when I pressed it, and it really did not like pulling away from a standstill- the biting point was somewhat vague.

It's on 107k, I've owned it since 60k and never had it open, thus I fully expect its on its original clutch. 

 

1 hour ago, FIVE-OH said:

It looks like the clutch arm locating arrangement is the usual spring type so I'd release that fixed end retaining clip to allow more movement to lever/wriggle the gearbox out.

Have released it, hasn't made a difference unfortunately. 

 

19 hours ago, Sir Anthony Regents-Park said:

clutch hose that is blocked and acting as a one way valve. 

Thanks for the info- I will be sure to check that out before re-assembly. 

 

Thanks for the suggestions Gents, I will try and get the pressure plate bolts out as they are hex's, and look just about accessible. Will report back. Cheers, David

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On 20/07/2021 at 16:46, hippie dave said:

(lower plate, three 19mm-head bolts on dowels, two 17mm bolts and entire starter motor). 

 

Four. 

 

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