Modern Vespa

Hi All,

In relation to my other recent thread entitled "Vespa 152L2 1959 - bent/misaligned crankshaft assembly?", can you please give me some advice on a suitable crankshaft puller tool?

I was going to use a few thick washers and the clutch basket nut to pull the crankshaft through the bearing. But the thread form on the end of the crankshaft, clutch side, is a bit worn and I'd prefer to use it as little as possible. So I was hoping for once to connect the puller and a second time for the the clutch nut.

So with this in mind can you recommend a suitable puller?

I had thought about a simple coupling nut and then a suitable length of threaded bar but what's the crankshaft thread on the clutch side? Is it M12 x 1.5 or M12 x 1.75 ? Do suitable coupling nuts exist? Or is there an enomonical puller designed specifically for this job?

Your help and advice, as always. much appreciated.

I have posted this elsewhere - so apologies if you're reading it twice. I'm in the UK.

Thanks

Chris

I don't know the size but it's prob best to buy the tool that has six different sizes since you will need it to pull in the main shaft, too. https://www.sip-scootershop.com/en/product/tool-sip-assembly-output-shaft-crankshaft_18119000


https://youtu.be/3dcL53WbqfY?t=124

https://youtu.be/fuP4kkR5K6Y?t=186

older and non sport model Vespas normally don't need a puller. The bearings go on the crank first and then the case is heated and the crank with the bearing is installed as one into the case.

see:

http://modernvespa.com/forum/post1795088#1795088
The correct way to build VBB engine

Thanks rowdyc for the tool recommendation and videos.

oopsclunkthud - my first attempt at a rebuild, I did have the bearing on the crankshft first but when the whole assembly was inserted into the clutch side crankcase, then the bearing did not sit uniformly in its housing. So the flywheel end was off at an angle and the crank locked up once the flywheel half of the crankcase was offered up. Upon closer inspection through the holes in the clutch side flywheel web you could see that the bearing wasn't fully seated on one side.

So this time I planned to fit the bearing alone first to make it easier to ensure it was fully seated uniformly. Then use a puller to get the crank through the bearing.

Hope that makes logical sense.

Regards

Chris

I did this for the first time on a VBC engine, which is the same 'oldie' style. It seemed alien to put both big bearings onto the crank first, then insert into the clutch side casing, as I'd previously only worked on later P series engines. The trick was to heat it sufficiently and to keep it true as you drop it in. I put the case into the oven at 100 degrees centigrade for 15 minutes. I got the angle slightly wrong first time, but was able to take it back out, realign it, then drop it in square before the casing contracted. I heated the flywheel side casing up similarly and it just dropped on beautifully

Thanks for the info swa45, but for me the engine is still in the scooter!

Cheers

Chris

the issue with pulling the bearings into the case and pulling the crank into it is that due to the seal being there the puller can't apply pressure to the inner race.

The puller has to apply pressure to the case>bearing outer race>balls>inner race.

Thanks oopsclunkthud.

On this Vespa the clutch side seal is on the outer side of the bearing. So are you saying for this setup I can't use the crankshaft puller method?

I can't use the puller because it will be butting up against the seal rather than the inner race of the bearing?

Does this mean I have to go back to my original rebuild method - put the bearing on the crank and then offer both into the heated crankcase?

I'm just trying to build my knowledge and ensure I'm doing it right.

Many thanks all.

Chris

Hello again oopsclunkthud.

I've read your previous post in detail and it's very informative, thank you.

http://modernvespa.com/forum/post1795088#1795088
The correct way to build VBB engine

This is basically what I did first time but the clutch side bearing wasn't uniformly seated in the crankcase. Maybe I should have heated the case again and taken a punch to the outer race to align it fully through the flywheel web holes? The flywheel side of the crank was hence out of alignment and when the cases came together the crankshaft locked up.

The only major difference I did was to install the seals on the crank and then insert the fully assembled crank into the case. Checking that the seal notch was aligned with the oil circulation hole. Hoping this would avoid damage to the seal when the crank passed through.

Was this a good or bad idea?

Cheers

Chris

The seal should go into the case first with a punch to seat it. This way the bearing is free to move in the hot case.

They make seal guides that thread over the end of the crank to keep from catching the seal on the threads, but a little bit of care is keeping it aligned while moving past the threads is all that's really needed. I bit of tape over the threads and maybe the key way is not bad insurance. bit of grease on the crank and seal helps too.

Thanks once again for taking the time to reply.

I've learnt so much.

I'd better give it a go now!

Regards

Chris