Primary rear cover to frame misalignment

[azcaveman]

I reinstalled the engine/gearbox on a 1961 A7 and cannot get the primary case to align with the frame. The mounting bolts for the motor, gearbox and rear case to motor (so they can rotate independently) are loose but nothing seems to be moving enough to allow the holes to align with gentle prying.

Also, I'm uncertain what fastener goes in there. It is a bolt with nut on the rear? Someone had a pic of an acorn nut on the frame and I found another pic with a hex bolt head.

Thanks!
Greg

[berger]

undo the two 5/16th bolts and it should drop into line, this problem did my head in a few years ago

[chaterlea25]

Hi Greg,
This link might help with the rebuild of the primary side?
https://www.a7a10.net/forum/index.php?topic=9646.msg70166#msg70166

John

[azcaveman]

Thanks guys. berger - I assume you mean the 5/16 bolts that attach the engine to the rear case? Those bolts are loose.
John - I read your excellent alignment guide twice. You mention spacers/washers in that location which I will keep in mind when checking the alignment but I'm still unable to get these holes aligned. I assume dynamite and 6' crowbars and not needed. 

[berger]

i mean the two bolts that fasten the inner clutch case to the engine, i fastened mine up and found the clutch sleeve and felt washer plate out of line and that bottom bolt hole untill i loosened them and pulled the case to line things up then re tightened them

[chaterlea25]

Hi Greg,
It might be a good time to check some of the frame measurements ?
There is a drawing in this post ,https://www.a7a10.net/forum/index.php?topic=6267.0

It should be a bolt and nut through the frame and rear primary case, any spacers needed should be fitted after
bolting the cases to the engine, enough to fit the "space" but not stress the cases

John

[JulianS]

Not had the rear fixing bolt on my A10 in the past 48 years of ownership and use. No ill effects so far.

Tried to fix one but so difficult especially when the rear chaincase is fitted so gave up the attempt.

The primary case is liable to distort if the fixing is not exactly in line.

[Peter in Aus]

Not had the rear fixing bolt on my A10 in the past 48 years of ownership and use. No ill effects so far.

Tried to fix one but so difficult especially when the rear chaincase is fitted so gave up the attempt.

The primary case is liable to distort if the fixing is not exactly in line.

That a good point Juli's, may be it should be left out, will have a close look at mine when I come to fit it, as I started out with a bent frame and if it want line up will leave it out.
Peter

[RichardL]

After figuring out how many washers I needed to fill the gap, I got so frustrated trying to manage the stack that I stuck them together with cyanoacrylate (super glue).

Richard L.

[terryg]

Richard, I thought you have or have access to a lathe. Admittedly superglue was much quicker in that instance.

[RichardL]

Terry,

Make-It-Here was an early victim of the pandemic. Nevertheless, My super glue fix preceded my membership.

Richard L.

[azcaveman]

Thanks for all the good info. Being lazy has always been one of my strong points so I"m inclined to leave it out and avoid any stress on the aluminum case. The front and rear cases have loads of screws to make them "rigid" and the frame is not benefiting from any extra support so I'm guessing it will not do any harm. 

[BagONails]

The inner and outer cases are very securely screwed together for sure. The pair though are quite heavy and they are only secured by the pattern of 5 screws at the front on the crankcase. I think this is why BSA felt the need to add additional support off the frame at the rear. Don't forget too that with the gearbox being adjusted separately to the engine for primary drive chain tension there is potential to load up the cases inadvertantly depending on condition of the sliding plate, clearances etc. Without the rear mount any loading on the cases is all transferred back into the 5 screws at the front. Then factor in road load shocks and powertrain vibration etc etc.  As Julian has said probably over engineered and maybe you don't need it but if it was me I would try to find a way to make things secure at the rear even if it means enlarging or moving a hole to do so.

Just my 2c and there are plenty of people with a lot more experience of these machines than I have on this forum but from a purely engineering viewpoint that is how it looks to me.

[azcaveman]

Good point! I was thinking that the thickness of the "tab" would be too weak when resisting transverse loads but I had not thought about the axial loads.