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MG MGB Technical - Starter motor and engine removal

I am preparing my 1980 UK spec MGB for engine/gearbox removal in order to change the clutch.
With most of the hardware removed now, the starter is still in-situ.
It looks a very tight fit with the steering column so close.
What is best practice re: engine removal...should I remove the starter first or is it less of a problem to leave it in place? Indeed is it essential to remove it first?
Any hints/tips appreciated.
ph barton

If you're only replacing the clutch, do you really need to remove the gearbox, or are you doing other transmission work?

For clutch work I would just remove the engine. It's a lot less work.
Dave O'Neill 2

Ditto engine only just for clutch or engine work, much easier then messing with the gearbox crossmember, propshaft, speedo cable, gear lever etc.

Starter removal is straight-forward, I've done it by removing the distributor and removing it from above on CB and RB both with the inverted oil filter. Hanging filter may need to be removed but that shouldn't apply to a 1980.

The biggest problem I had on the RB was the engine mounts. The steering rack needs to be removed to access the chassis mount nut that side, it can be done without but is not worth it. On the RB both nuts were a real struggle being seized to the studs despite copious releasing fluid, someone on a rope pulling on the spanner, and eventually drilling through the edge of the mount and the chassis bracket and inserting a pin to stop the rubber twisting and absorbing all the spanner movement.

After that it's easy! Remove all the bellhousing bolts except the bottom two, lift the engine until the bellhousing touches the tunnel, support the bell-housing there, then undo the bottom two bolts and pull the engine back off the gearbox.

Check the alignment of the release bearing to the first-motion shaft. Mine was way out of line and had caused failure of both graphite and 'roller' bearing release bearings in my ownership, annoying when the friction plate isn't half worn.
paulh4

Thanks, I've had a problem with engaging reverse. Nine times out of ten the gearstick won't travel far enough left to go into gear. I have to ease the car forward a few inches then put into reverse. Always goes in the second time.
On a couple of occasions when slowing down as I disengage the o/d in 4th it slips out of gear.
Any suggestions on these faults?
Also can you advise on which wires to detach from the gearbox when removing engine/gearbox together? (1980 car}
I have removed the two wires connected to the gearstick o/d switch. What other wiring, if anything, needs to be detached to allow the g/box to come out unhindered?
Nothing looks very accessible under there! Any tips??
ph barton

I'll say up front it's unlikely to be anything to do with the clutch. If it was it would grind moving it towards reverse as there is no synchro, and moving it would do nothing other than having released and re-operated the clutch.

Baulking at 1st and reverse is not unusual, especially on BMC gearboxes, although to be fair I've never had a gearbox of any manufacture that I could guarantee getting 1st and reverse first time every time. Nowhere near as bad as nine times out of ten for me though.

When it happens I nudge it towards 2nd then it usually goes in, if not 1st then 2nd, and if not then neutral, clutch up and down, then I think it's fair to say it always goes in. Never need to roll it, which is only moving things much like clutch up and down.

But as bad as that, and the jumping out of gear, points to a gearbox rebuild being needed, in which case you would fit a new clutch kit as well anyway unless it's on;y just been changed.

If removing the engine and gearbox together you do have to remove the gear-lever so those wires would need to be disconnected if not already done. Others are where the three wires from the gearbox sub-harness join the main harness by the bulkhead, then the sub-harness comes out with the gearbox, it can stay on the gearbox switches until the gearbox is out.
paulh4

Number one check for me is always simple basic stuff (that often gets overlooked) would be the oil level in the gearbox and the state of the oil.

The gearbox oil is a service change every 2 years or 24k-miles whichever is the soonest. Many cars have gearbox (and rear axle) oil is this many years, or decades, old. Especially if engine oil is used in the gearbox it doesn't last fully functioning forever.

I would always prefer to do a hot thorough oil change on gearbox, engine and rear axle. I'd also want to do a flush/clean but if the engine is out you can't run the car for the hot oil drain so that will have to wait and you'll be on what most do which is a lot less thorough just cold drain.

I'd do all this before removing engine or gearbox or leave until after engine and gearbox go back in so as to get the oil and muck hot and stirred up ready for more thorough draining.

See below.

AS Paul has put to engage reverse you need all engine revs to have fully dropped and even then give it a second or two to settle and clutch pedal fully down, same for first. Having the choke out of course increases the revs so more allowance required.

For the overdrive again the oil will be important, and not taking your foot off the accelerator when engaging OR DISENGAGING o/d, the o/d needs load not coasting, both ways.

Again for o/d oil change and cleaning of filters can do wonders - but not repair parts.

After drain I'd look to see if anything needs doing on gear lever bush and plate.



Nigel Atkins

Oil level is important of course, even more so for correct OD operation, but as the jumping-out problem occurs when _disengaging_ OD it's more likely to be worn detents in the main gearbox. My V8 never actually jumped out of gear but decelerating in 4th I could feel the gear lever moving forwards a bit to move backwards a bit when accelerating again - not due to gearbox movement. Moving forward was enough to disengage OD, which is on 4th only on that gearbox, to engage again when accelerating, which made for rather jerky progress. When taking the leather and rubber gaiters off I was surprised just how much lighter that made the gear change. The pressure from the rubber one is trying to pull it out of gear all the time.
paulh4

Sorry I misread that as slipping out of overdrive rather than 4th gear.

As Paul has put the rubber gear lever grommet/gaiter can cause a lot of hassle by being over tight. If it is a replacement modern made part then like most modern made rubber parts they are always to be suspected.

Again checking if the rubber gear lever gaiter/grommet is causing issues is very easy and free, just unscrew the fixings to it and test drive.

Also consider the clutch hydraulics in clutch problems, again bleeding or changing the clutch fluid is often forgotten about for very many years so now would be a good time to deal with this fully.
Nigel Atkins

Clutch problems cause grinding when trying to select reverse with the MGB gearbox.
paulh4

True clutch problems cause grinding when selecting but which part of the clutch system and other things can cause the same not related to the clutch as such or directly.

ph listed a few different issues, the limited gear lever movement doesn't suggest that is clutch related nor the slipping out of 4th.

There could be, as often happens, more than one thing contributing to the issue resolving just one might not fully sort things.

As you know I much prefer to address the easy basic service/maintenance or repairs first as you can't successfully progress without dealing the basics first and they'll need to be addressed later anyway.

Two items we don't know about in this thread are ph's experience and knowledge of owning and driving his car and the car itself.

My wife's modern has times when I have to rock it or go to first before I can get it into reverse, now that could be me and the way I operate the controls or the gearbox as it is or a combination of me and the gearbox (but it's not the clutch).

ph seemed committed to replacing the clutch so I think it's even more important to also follow the other advice you and I have given to get a good result from that work.
Nigel Atkins

Guys,

Am i right to assume , that when just removing the engine (rather than the engine & gearbox), that you need to take out the four bolts holding the gearbox cross member to the chassis rails & then support the rear of the gear box as well as the front when raising it to the top of the transmission tunnel to enable the gear box to pivot so that the engine can be pulled away from the gear box? (I have used the method of removing the four bolts to enable me to lower the gearbox to gain access to the overdrive switch on the top of the gear box when i rewired the gearbox harness).

Cheers,

Charles
Charles9

There should be enough flexibility in the gearbox to allow you to raise the engine, then support the bellhousing while separating the two.
Dave O'Neill 2

Ditto - more than enough flexibility in the mount rubbers. The front of the gearbox will be hanging from the engine until you have lifted the engine so the bell-housing is at the top of the tunnel, then the bell-housing is supported on a jack to just take the weight, and the two bottom bell-housing bolts can be removed and the engine pulled forwards.

It's important that the hoist and the jack are taking close to equal weight or when the bolts/nuts are slackened the tilt relative to each other which risks bending the first-motion shaft. Sounds horrendous but just keep an eye on the gap between the two as you start slackening and make sure it is equal all the way round.
paulh4

Thanks Guys,
I thought that would probably be OK - not planning (& hopefully don't need to pull the engine out just yet), but take the point that if the gearbox & overdrive are OK , then preferable to just take out the engine when clutch changing or dealing with specific engine related issues.I've read Paul's notes on his site which describe how it was done in a single garage with limited headroom which are very helpful ,but just needed clarification as to the gear box mount bolts. (A lot safer leaving them in situ)!
Cheers,
Charles
Charles9

Update:-
Removed engine and gearbox together with no issues. Clutch was very oily, mainly on gearbox side. Evidence of significant leakage of oil through front gearbox seal. Also evidence of slight oil seepage from rear crankshaft oil seal ( a shadow of oil stain below seal on backplate) Car was juddering badly on moving away once warmed up.
Will probably get an exchange g/box. Any experiences of Heathrow Transmissions out there?
Stripping down engine now....please see my problem with removing tappets on separate thread. Thanks all.
ph barton

"Car was juddering badly on moving away once warmed up." - Now you say! That could be clutch! 😉
Nigel Atkins

On the gearbox issue
If it was leaking oil from the front and also jumping out of 4th then there is the possibility that the front bearing has collapsed or worn badly worn allowing the front shaft to move about enough to flick it out of gear-it doesn't take much.
You mentioned getting an exchange box, all good but you will also need to have a good look at or replace the spigot bearing in the back of the crankshaft as this will probably be badly worn if the shaft has been flapping about

willy
William Revit

PH-
Willy is correct in warning you about excessive wear of the crankshaft spigot pilot bushing. A working clearance gap of approximately 0.003" (0.08mm) between the crankshaft spigot pilot bushing and the pilot shaft section of the input shaft/first motion shaft is correct.
Stephen Strange

This thread was discussed between 18/03/2021 and 10/04/2021

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