Stiff crank

[L4Lambretta]

Hiya all,

First up, I'm down under, so don't tell me to take it down the local dealer, coz there ain't none.

Putting together my first engine: S1 casing with a CasaLam GP crank, seals, bearing etc. Using a GP 150 SIL mag housing.

Problem, put the crank in. some slight resistance. how loose shoud the crank be in situ? When I put the mag-housing on (new bearings etc) the crank is stiff and with moderate resistance. Did it all following the Sausage DVD and sticky's book v.v. carefully.
Used a classic bike specialist to fit main bearings -he knew his way around the engine, but...

Clearances look OK, but any idea what the culprit might be before I pull it apart again?

Many thanks

L

[J1MS]

Should spin fairly freely with only light resistance... Sometimes you get a tight fit on the seals... But other times a seal. Can flip as the crank is pushed into the main bearing or as the mag housing is pushed home... There are other reasons for a crank not spinning freely but usually the seals on a fresh build are tight or have flipped

[L4Lambretta]

This is doin' my head in...can somebody answer some questions before I pull it apart again, please?

New casa crank doesn't spin freely in situ, but is okay with a little hands on guidance. The crank on the old GP motor I've got spins loose and free by comparison. How much play should there be in a newly fitted crank?

Crank looks fitted okay; there's a .25mm gap between it and the case.

Fit the mag-housing and everything stiffens right up. As far as I can tell i've fitted new bearings, seals etc correctly. I'm thinking
the seals are at fault here; causing friction against the crank. It's a SIL GP 150 mag-hosuing to a series 1 engine.

How much play should the mag-housing allow once fitted? Do the rubber seals sit so tight that they cause such friction. Any other ideas?

Many thanks -this is the 1st engine build for me, so obviously learning as I go.

cheers

l

[red ghost]

First up, I'm down under, so don't tell me to take it down the local dealer, coz there ain't none.

Yep, that old chestnut. I'm on the Gold Coast, so I know how you feel.

[dapper]

I found that the seals do give some resistance to turning the crank by hand, and this should be expected with new seals, and even existing ones if they are doing their job properly. You shouldn't expect the crank to spin freely. Do make sure you have a gap between the mag housing and crank and on the other side of the crank too. You did lightly grease the seal lip and the crank before fitting? Did you also make sure the crank was fully pulled home, either using a crank puller or the splined sprocket shaft? Did the mag housing seat fairly easily when bolted down?

[J1MS]

would expect light resistance with the flywheel on, but easily spin without too much effort... Possibly the Drive seal has lipped (caught on the oil seal shoulder) so is not sitting correctly, this can cause stiffness at the crank...

when you check a crank try checking webs, top and bottom clearance, also webs to both sides... between mag and web... also oilseal plate to web... There should be no pronounced tightening and loosening with a slide fit feeler gauge inserted in the gaps... I normally spin the crank while checking by the rod... but if someone is there get them to slowly and evenly to spin the flywheel... while you check clearance...

[tavspeed]

if new seals have been fitted,when turning the crank by hand it will feel stiff,and if turning by using the conrod will feel very stiff.as long as the resistance to turning the crank is uniform throughout its 360 deg travel,it will be ok,if it tightens up in certain spots you have a problem,it will be ok.when the motor has been run the seals will soften up or run themselves in.so if you split the engine,you would be able to turn the crank much more easily by hand,have only come across this using rolf seals,there are different makes available from lambretta dealers,i.e pioneer which seem to be more flexible than the rolf equivalents.cheers all.

[L4Lambretta]

thanks guys for the responses; it's the little details that count...

Sounds like it's actually as it should be, although I'll do all the checks again. I just thought that
the crank should spin real freely when fitted. Having said that, the flywheel hasn't been fitted yet,
so I've been spinning by hand...just goes to show that knowledge comes from experience.

I should mention how excited I am to be fitting my casa kit, variatrinic and disc brake. I'm a bit like a kid at Xmas time, but I do want to take it slow & check EVERTYTHING!

Thanks guys,

PS, Red ghost, did I meet you up in the GG? was there in '06,07,09. got to know the Cane toad boys. Go by the name of Strutts....

[red ghost]

Red ghost, did I meet you up in the GG? was there in '06,07,09. got to know the Cane toad boys. Go by the name of Strutts....

Can't say we have meet.. but I'm thinking of going to the Boreen Point rally in Nov. and Stanthorpe next year..

[Bilko]

Fitted my crank last night and I've got resistance.

It's how I remember it too.