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MG MGB Technical - Engine Gearbox mating

I have been trying all day to get the engine back into the car. It will not mate up to the gearbox. I used the clutch alignment tool but it will not close the last one and a half inches. I am wondering if it could be the spigot bush as this was replaced but the alignment tool went through OK when fitting the clutch. The new clutch plate fitted the gearbox shaft without binding so I am stumped. Any tips would be helpful.
Trev
Trevor Harvey

Could be that the splines are not aligned with the clutch disk.

Try putting the transmission in gear, and turn the rear drive flange while pushing the transmission and engine together.
Daniel Wong

It needs a perfect alignment and takes much patience, especially if you're unassisted.

Working alone, I've had success by "squaring" the engine/ gearbox, keep a bit of pressure between them, then gently nudge/jiggle/rotate the crankshaft nut.

As Daniel suggested, but working the engine instead of the driveshaft.

Much patience, but eventually it will slide home. I think it's a matter of luck too. One time it took an entire day to get it, another time only 10 minutes.

Philip Collura

Is the distance apart the same looking in from above as it appears from beneath? I've found that a simple jack under the front of the transmission often helps align the transmission and engine in the same horizontal plane. Don't know what year your B is, but most require some elevation to the transmission because with first insertion of the shafts, the engine is at the wrong angle to the transmission plane in order to clear the height of the front crossmember. Hope that makes sense. Also, if alignment appears to be correct (same gap distance all the way around) try turning the end of the crankshaft a little to align the splines. I've done this a few times and know the frustration. What's amazing is that when you get it just right it slides into place perfectly with no effort at all. There are some colloquial expressions that we use here in the U.S. that can be used, but I don't remember which ones worked the best. Couldn't post them here anyway.
Rick Penland

I've always done MG engine/gearbox as a unit so don't know all the difficulties when the gearbox is in the car. But I've done this on American cars.

First, cut the heads off bolt that will fit into the block (leave enough so you can remove them. Then try to use these to guide you the units together. This should take care of the up/down and side to side misalignment. Then you can work to eliminate the angular misalignment by rocking things around. I've had good success on this with American cars where there is a bit more room. Once you make the fit, remove the guidebolts and replace them with the correct ones.

After getting by engine/gearbox together in the shop I found I had a rubbing noise in the gearbox when I turned the engine over by hand. I had to loosen all gearbox to engine bolts a bit and move things around to relieve a bind.

Eventually you'll get it.

Regards,
Bob McCoy
New Hampshire USA
Robert McCoy

There have been a couple of comprehensive threads on this recently. Notably a number of people including myself have pointed out that the plastic "alignment tool" are near worthless and especially deceptive for amateurs. Even a proper input shaft or other machined tool needs to be used correctly.
Try looking up these earlier threads, but you are likely to have to pull it back out and reset the clutch alignment.
Since you are UK, call up Chris Betson, who squirrels away dead inputs for use/sale as real alignment tools.

FRM
FR Millmore

When I did my first clutch replacement on a B, I discovered that a length of steel conduit - as used in electrical installations - fitted perfectly through the clutch plate and into the spigot bearing.

From what you have said, you have alraedy tried the clutch plate on the input shaft splines. I once had a similar problem to you, in that the engine just would not mate to the gearbox. When I eventually removed the clutch plate, I found that it wouldn't actually go onto the splines at all.
Dave O'Neill 2

"Notably a number of people including myself have pointed out that the plastic "alignment tool" are near worthless and especially deceptive for amateurs"

Interesting point, so an old input shaft could sort out this issue?
Rgds.
Guy RENOU

Thanks all for the advice. I have managed to get the engine and gearbox back together after another frustrating half day. FRM I think you are correct regarding the plastic alignment tool as no way would it go on using this. I was not sure if it was fouling on the spigot bush or clutch plate. So I removed the clutch and then tried them and it went on. I then new it was not the spigot bush that was causing the problem. I put the clutch back on but left the bolts lose but enough to hold the plate in position (about two turns). When the engine went in this time they went together aligning the clutch plate. The engine was removed again carefully, the bolts were done up and then refitted. I was very relieved.
Trev
Trevor Harvey

The best alignment tool is a piece of steel bar turned on a lathe that tightly fits the spigot bush and the insides of the splines of the clutch disc. I would also advise grinding a 1/32" at 45 degree chamfer on the end of the spigot shaft to ease alignment. Now the gearbox needs to be jacked up until it touches the transmission tunnel in order to get the gap between the backplate and the bellhousing parallel all round. Once you have this slide the splines into the clutch disc by putting the transmission in gear and then turning the crank nut until the splines enter. then with the two units parallel push the engine back on to the gearbox. Sometimes a lever between the front of the engine and the crossmember helps to move the engine that last inch into place.
Iain MacKintosh

Having fitted hundreds of clutches in the last 30 years I always use a small square file to file a small lead on the clutch plate spline - makes refitting a breeze. You must also put a small ammount of clutch plate spline grease into the plate - it usually comes with a clutch kit.
Garth
Garth Bagnall

This thread was discussed between 12/02/2010 and 16/02/2010

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