Gearbox cross member alignment

[Steve_k]

While doing the drivers floor pan I noticed a couple of bolts missing on the gearbox cover. I thought maybe the threads need a tap running through the the holes or maybe a broken bolt to drill out. what I found is the cross member is not lining up with the chassis holes it looks like the gear box mounts are not right and all twisted.

Any ideas is something been fitted wrong at some point ?

Thanks in adavance

20180826_160537.jpg (94.38 KiB) Viewed 1413 times

[philthehill]

I cannot see anything really untoward.
Your gearbox rubber mount shown is detaching away from the mount steel plate that attaches to the cross member and needs to be replaced.
The bottom two holes of the cross member are slotted so some alignment adjustment may be found there.
The misalignment of the holes is not unusual especially with a car that has had underside welding.
Use a tapered bar in the chassis rail/cross member holes to get the alignment right.
You can adjust the top ends of the crossmember holding the captive nuts by closing or opening the ends of the crossmember to suit.

[Steve_k]

Thanks Phil

I can bar the holes inline without any problems and make the cover screws fit, all the engine and gearbox the mounts will be getting replaced the one in the photo hasn't separated yet. The rubber mounts are under quite a lot of strain its like the gearbox is too far back but it is not the clutch linkage shaft is straight and square as it should be

The chassis rails are original very solid and never been welded so the misalignment of the gearbox cross member must be something fitted wrong or how they are from the factory.

Thanks

[myoldjalopy]

This reminds me of a similar problem I had with a Minor a long time ago when replacing the engine and gearbox. So long ago I can't exactly remember......but it was a struggle to fit the gearbox back properly and IIRC it was something like 'someone' (not me!) had either put the gearbox cross member on back to front (if that's possible?) or had put the gearbox mounting brackets on the wrong sides (they are handed) and had just jammed everything back in under tension............something not easily spotted at first but easily rectified once the cause was identified.

[johngrigg]

The cross member,or at least mine, is helpfully stamped 'front', notwithstanding which I have tried to install it back to front on a couple of occasions........which is impossible, if anyone has achieved this they deserve congratulations for perserverence and brute strength

[philthehill]

Having just examined a standard crossmember in excellent condition with no distortion or twisting I still cannot see much wrong with your crossmember.
The holes for the captive nuts are 3" apart with some slight fore and aft movement of the nut in the cage.
The bottom of the cross member rubber mount has a two pronged tang which fits either side of the tag at the bottom of the rubber mount seat.
As regards the distortion/loading of the rubber gearbox mount - it has to be remembered that the total weight of the engine and gearbox is only supported at four points two of which are the gearbox mounts.
I would suggest that you disassemble the mount assemblies, replace both of the gearbox rubber mounts (they do need replacing soonest) ensuring that the gearbox mounts are the correct ones and they are fitted correctly especially the inner rubber mount special fitments.
Fit all back together but do not fully tighten until the weight is on the rubber mounts and then see how it relates to the chassis rail.
Phil

[simmitc]

Was the car level when you took the photo? If the front was raised even slightly then the weight of the engine and box will start to push backwards. The front engine mounts also have adjustment, so when fitting new gearbox mounts, slacken the front mounts a little and let everything settle on a level car before final tightening. Also fit all cross-member bolts before tightening the mounts (you can leave the gear box cover off, just locate the top bolts to ensure that the cross-member is correctly aligned).

You should also ensure that the engine steady bar is slack when settling the engine and box on new mounts; and then adjust it correctly - some people make it much too tight which can then twist and pull back the engine, as well as introducing vibration.

For reference, as well as having "Front" stamped on the cross-member, you also have the attachment point for the gearbox steady cable that has to go at the rear, so it is quite clear which way round it goes.

[Steve_k]

Hi thanks everyone for the advice, the car is level and on axle stands on the garage. I will do as suggested strip the cross members and mounts off clean everything up fit new rubbers then when refitting slacken the front engine mounts stabliser on the head see if it lines up better.

[philthehill]

As regards the embossed 'FRONT' on the cross member.
The engine steady wire was not originally a factory fitted item only from Car No: 264013
The engine steady wire was originally fitted as an retro after market mod see BMC Wksp Man Section: AA36 and Fig: AA28 for details.
Once the engine steady wire was fitted the embossed 'FRONT' became irrelevant as the steady wire bracket was always attached to the N/S/Rear face of the cross member in line with the steady wire bracket fitted to the gearbox
Before the engine steady wire was incorporated it was important to get the cross member the right way round as the right way was not always apparent - so the need for the embossed 'FRONT'.
As an aside:-
When BMC fitted the steady wire front bracket they should have increased the size of the studs in the rear of the gearbox to 5/16" and used UNC threads where they fit into the gearbox but BMC decided to use what was already in place which was 1/4" UNF.
Increasing the size of the studs with UNC threads fitted into the gearbox is a worthwhile modification which I have undertaken many times and can highly recommend.

[myoldjalopy]

OK, thanks to those pointing out that the problem I recall was not likely to have been the crossmember being fitted wrongly. Therefore, it must have been the mounting brackets fitted the wrong way round. Sorry I couldn't remember exactly - but it was nearly 30 years ago!
So, Steve, just make sure yours are fitted the right way round.