Alignment.

[Mouse]

How do you generally get the shafts aligned in a longitudinally mounted gearbox ie a BMW, Guzzi, or Dnepr etc. I've kind of ignored this technical issue until I now need to make the mounting plates. The BMW gearbox has a recess that locates precisely in milled recesses in the engine but I'm having difficulty in working out how I might repeat this alignment myself.

I'm concerned that if I get it misaligned by as little as 1mm the centre of the clutch centre will get ripped out in next to no time.

I've looked at a couple of car engine clutches and their centre splined bit is floating in the inertia spring (Correct name?) assembly that will take a small amount of misalignment even though its probably not designed to. I've fitted several large electric motors to car gearboxes in the recent past and had good success which probably has something to do with this tolerance inherent in the clutch plate. However I'm stuck with using the BMW clutch unit as I'm unable to find a car clutch plate that fits on the spline. The BMW R80 clutch plate has no such springy mechanism and the only free movement is the gap between the splines and that is next to non-existent hence me worrying about getting it right and then ensuring its right when I come to take the gearbox off and on again.

Has anyone developed any handy hints that might help me.

[Sphere]

Hope you don't mind if I lurk this thread. No answer though. I'm sure there's a nice trick to it.

[Mouse]

Hang around, bouncing ideas of random people often highlights something you've not thought about

I've been asking around and have a couple of tricks to try out.

The first is making a rod that will snugly go down the gearbox centre shaft and locate the dimple in the engine output shaft. This will get it close but as they say 'Close, But no cigar!'

I'll also be using tapered engineering pins or whatever they are called so once I've got it perfect the pins will locate it after dismantling.

[Crazymanneil]

like sphere, I think this could be an interesting thread, always wondered about this. A brute force approach would be to get the parts precision measured someplace, but I am sure theres a trick to this.

N

[johnfireball]

Hi Mouse,
What gearbox and what engine are you mating? I have an allignment tool for a diahatsu turbo diesel mated to a dnepr gearbox. I had it specially made,it slips into the center hole of the engine flywheel where the original gearbox shaft fitted and the other end fits snugly over the gearbox splines. I turned the engine, flywheel facing up with bellhousing plates mounted to engine and gearbox worked out the correct spacing and tack welded spacer bars between the bellhousing plates next unbolt the gearbox, remove bellhousing from engine and weld. If misalligned the gearbox bearing will fail very rapidly.
John.

[OilyPhil]

hi, here is a pic of the adapter I made to align my BMW box with kubota d950 engine.

[img][IMG]http://i590.photobucket.com/albums/ss34 ... LD0001.jpg[/img][/img]
The hole is bored to be a tight fit over the splines (tricky as splines were worn tapered) the threaded hole is to take a bolt to draw it off the shaft. The other end is machined to be a good fit in the centre of the kubota crank. Here shown loosely in place on end of mainshaft.

[img][IMG]http://i590.photobucket.com/albums/ss34 ... LD0002.jpg[/img][/img]


and here shown on end of crank, note I have placed engine on its end so gearbox weight doesnt twist it.

[img][IMG]http://i590.photobucket.com/albums/ss34 ... LD0003.jpg[/img][/img]

hope that is of some help, Phil

[Sphere]

Credits to Phil

hi, here is a pic of the adapter I made to align my BMW box with kubota d950 engine.

The hole is bored to be a tight fit over the splines (tricky as splines were worn tapered) the threaded hole is to take a bolt to draw it off the shaft. The other end is machined to be a good fit in the centre of the kubota crank. Here shown loosely in place on end of mainshaft.

and here shown on end of crank, note I have placed engine on its end so gearbox weight doesnt twist it.

hope that is of some help, Phil

[OilyPhil]

Hi Sphere, thanks for doing that, what did I do wrong when I inserted the photos from photobucket?

Phil

[Sphere]

Too many IMG tags and for longevity I opted to upload the pics to the forum database so photobucket can topple and we'll still see the pics. But don't worry I'm very glad you posted it.

[OilyPhil]

The pic where it is loosly slid over the splines on the gearbox,not the crank, the bit that is turned down goes in the centre of the crank, the bottom pic shows the adapter in the crank, the hole where the gearbox splines fit can be seen.

Phil

[OilyPhil]

Does this diagram help?

Phil

[Crazymanneil]

Interesting stuff indeed. How tight does the adaptor go on the splines? I imagine its a balance between a tight fit for alignment and not so tight that you gotta beat the thing on with a hammer (not good for bearings?).

Great solution though, I always wondered how this is done.

N

[OilyPhil]

As for fit I went for a 1 thou interferance fit on the splines, and dead size in the centre of the crank. I fitted it first on the gearbox (warmed it up slightly so it went on easily, but stayed put when it cooled, bolted the machined bellhousing to the gearbox, placed the whole lot onto the crank ready to weld the bellhousing to the adapter plate. Just waiting to get my new TIG welder set up then I can weld it, Ill post some more pics then.

Phil

[Crazymanneil]

Thread tidied up, think the descriptions etc are good now. (thanks sphere)

N

[mark_in_manchester]

Hi All -

I 'aligned' a Ural 'box onto the adaptor plates I made to fit it (including Ural flywheel and clutch plates) onto a Daihatsu charade engine. I did it using a buggered (v.rusty) Ural clutch shaft I happened to have, into the end of which I jammed a pointy piece of steel about 5mm long. I'd already fitted the flywheel to the crankshaft, concentric to a couple of thou, by shrinking a bit of scrap into the middle and boring a hole to the right size on my lathe, to fit the boss on the end of the car crank.

I assembled the whole clutch (incl springs) loosely, and held it together with some overlong bolts which tensioned the springs just enough so friction plates would _just_ slide around, but generally stay put. I then pushed the splines on the 'tool' through the splined centres on the friction plates, until the pointy addition located in the square hole (~3mm long sides to this hole) in the middle of the clutch release plate. This sits 'under' the friction plates, and sandwiches the springs back onto the flywheel - the clutch rod usually locates into the square hole. This is pretty concentric with the flywheel, since this plate slides on 6 'legs' which are integral to the flywheel, and the chatter is reasonably minimal.

Having centred the friction plates, I could then offer up the complete 'box' to the flywheel fitted to the engine, and mark its location on the adaptor plate onto which I wanted to fit it.

It seems to work...

M.

[coachgeo]

congrats on your steps you conjured up working for you thus far. Look forward to pics to give more clarity to this part of your plan.

[Mouse]

(I know this is a duplication of the build thread but would be useful for anyone else searching in the future. )

For this to work properly I need to get the engine shaft and the gearbox shaft aligned as best I can, preferably perfectly.


I've borrowed a friends magnetic surface gauge to help me. The magnet is stuck to the cast cylinder fins and the business end is on the inside of the flywheel centre bush I made.


Now in order to turn the engine with minimal force I took the rockers off and removed the push rods so I'm not having to compress the valve springs. I also inserted the bit of wood so the valves are kept open a bit and there is no compression.


The error is 0.006" or 0.15mm. I'm not happy but continue.


Inserting a length of 9mm ground bar the error is now 0.005" 0.13mm.


The clutch push rod is 8mm and the hole is 9mm which is a perfect match for a length of 9mm ground bar which is oddly enough an available standard size. The gearbox slides over the 9mm bar. The flange is held down but not tightened so as the engine is rotated the surface gauge will indicate the error in alignment. It is unsurprisingly 0.005" out

Not happy with 0,005" I took it all apart and back together about three times and after a bit of tapping with the rubber mallet I managed to get it so the surface gauge didn't flinch at all as the engine was rotated


You'll have to take my word on it that this is where the needle stayed!! I'm not saying the thing is aligned with absolute perfection but it s now within the free play in the alignment tooling and spline coupling and I ain't going to get better than that.
After this was achieved the bolts holding the flange plate to the bell housing were very carefully nipped up tight.


After that the gearbox was removed so that locating holes and pins could be fitted.


These are the engineering pins and the hole they go in. They are tapered ones so I had to ream the 6mm hole out with the correct matching tapered reamer.


In it goes....


And tapped home with my smaller hammer = Everything in alignment again

If you look at the photos you'll see that the inside hole of the adaptor plate is circular. It is a little known fact that the locating lugs on the BMW gearbox are circular and concentric to the input shaft allowing easy machining of an adaptor. The correct sized interference hole was turned on a lathe from of a sheet of 4mm steel bolted to a face plate.