1955 Model D150 (version 2) - Torsion bar, lever and link

[Big Al]

Can someone please tell me the order for dismantling these parts?

Do I drive the torsion bar out by tapping it from the flywheel side so that it comes out on the carburettor side?

[jbcollier]

No, the other way.

https://jbcollier.smugmug.com/Scooter/i-gZ2b3SM/A

[Big Al]

Many thanks for your answer and the link to the diagram.

But before I can do that, I think I need to drive out the forwardmost pin holding the figure-of-eight link, (the one nearest the inlet manifold) leaving the link attached to the lever arm at the rear end. It also looks as though I need to remove the flywheel to get to the link pin, as the flange is in the way. Is that right?

To remove the link pin, I understand I need a special tool. Any suggestions where I can buy, or hire, one of these please? I live in East Sussex (Brighton & Hove).

[jbcollier]

You do not have to disassemble the engine to remove the torsion bar... in theory, that is. I removed and installed my engine as a unit. Might be helpful to remove the carb and intake manifold though. Get angled circlip pliers and remove the clip securing the pin. Push the pin out towards the carb. In theory, it comes out. In practice, it can be somewhat rusted in place and then you will have to improvise, maybe some heat, to get it out.

[Spash]

If you need a tool to refit the torsion bar I have a drawing that you can have a copy of to get one made. It was for an LD MK3 but I assume they are the same. Nothing over complicated just a bar with off set diameters. Cambridge Lambretta sell them for £32 plus postage.

If you want a copy (or anyone else wants a copy) please drop me an email at:

saraitoo@aol.com and I will send it.

Cheers

Spash

[Big Al]

Thanks to both of you for your replies.

I've just managed to find my old copy of the UK-published "Official Home Lambretta Workshop Manual" (the one with the blue front cover and the picture of the GT200). On Page 160 it says: "do not attempt to force the larger end of the bar on the offside through the smaller splined hole on the nearside" (which is the flywheel side). So it does seem fairly certain from the book that you tap the bar from the flywheel side to push it out on the carburettor side.

It seems that I can wait until the engine is on the bench and freed from the frame before knocking out the torsion bar, because uncoupling the forwardmost part of the link from the lever arm will still leave the lever arm (and the torsion bar) with the engine.

The picture of the whole torsion assembly on Page 160 shows there is a shoulder on the lever arm link pin on the flywheel side, so the pin can only be driven out towards the flywheel i.e the opposite way to the torsion bar removal.

Spash: My email address is ajhobden@btconnect.com
I would be grateful if you could send me a copy of your drawing.

Many thanks, Alan.

[Big Al]

My mistake! I've realised that, once the engine is uncoupled at the top (lever arm) link, the torsion bar and arm will be left attached by the bar through the frame, so the engine comes out without them.

I'm sure some of you guys could write a better explanation about the torsion bar assembly than those in the various books!

[Spash]

Hello Alan,

I have sent you the drawing and other stuff that you may find useful. I have a PDF of the parts book but it is too big to send however if you check the following web site you can download it yourself:

http://www.scooterhelp.com/serial/LD_D.parts.html

Good luck

Spash

[Big Al]

Many thanks Spash. I have now received your email and drawings.

John, thank you for your patience. I've compared your torsion assembly diagram with the one on P160 of my book, and realised that the one in the book is actually a mirror image of the way the assembly actually sits in the scooter, so that's very unhelpful of the publishers. The shoulder on the link pin is on the carb side, so the pin must be driven out towards the carb as you said.

I'm still unclear about the actual torsion bar. The book says " do not attempt to force the larger end [22 splines] of the bar on the offside [carb side] through the smaller splined [21 splines] hole on the nearside [flywheel side]. So this indicates that you drive the torsion bar from the flywheel side towards the carb side, which is what I suggested in my first post. Can you clarify this please?

Many thanks
Alan

[jbcollier]

The torsion bar slides into the frame and is retained by a snap ring. The torsion bar "arm" slides over the torsion bar into bushings also in the frame. The torsion bar goes through the arm and holds the arm in place with another snap ring. Disconnect the link and remove the torsion bar snap rings. Then the arm should slide off. Mine was seized and required some persuasion with a brass drift and a hammer. It was a while ago but I think I drove out the torsion bar from the carb side and the arm/torsion bar assembly came out.

[Big Al]

Thanks John.
Can anyone else throw any light on which way to drive out the torsion bar itself please? The last thing I want to do is damage the frame, or any other part for that matter.

[Big Al]

Re: magneto flange.
I've just marked the position of this flange, which is threaded to take the flywheel cowl fixing screws, and removed it by slackening the pinch-bolt (8mm socket), and simply pulling it off. Luckily, my D has the small flywheel. Apparently I could not have done this if the flywheel had been the larger version.
I can now easily get to the pin in the figure-of-eight link, either to just push it out towards the carb/crankcase cover if it's fairly free to move, or to get a drift onto the end of it.

[Steve J]

A couple of things - if the alloy flange which clamps onto the outside of the mag flange is rotated (just slacken off the clamp screw/bolt), it's easy to get to the front pivot pin in the 'figure of eight' link. The pin is driven out towards the left hand side of the scooter, but if you attempt that without the proper tool, or finding some other way to take the loading of the torsion bar off the link pin bearings, simply driving it out will damage or destroy the needle roller bearing in the link. If you can extract the rubber buffer on the rear of the main engine casing to let the engine swing back a bit further, it might help.

As for damaging the torsion bar or frame, it's very unlikely, provided the pre-load of the torsion bar has been released before you attempt to remove it. If I remember correctly, the idea is to drive (i.e. strike with a large hammer & drift) the bar from the LHS of the scooter until its splines disengage from those in the torsion bar link casting. When that is done (in theory), the torsion bar link is pulled free from the frame. The torsion bar itself can then be driven out from the RHS, so that is driven free of its splines, and it is pulled out of the pivot tube from the LHS of the scooter. So much for the theory - the torsion bar link is often seized solid in the brass bush in the frame, and it can be a real pig to remove - penetrating oil, heat, and a very large lump hammer are the usual tools.....

[Big Al]

Thanks, Steve. Your comments are very helpful. As I had marked the position of the mag flange before loosening the pinch bolt, I found I could either rotate it (which, as you say, is all that's needed to give clear access to the link pin) or just pull it off and put it out of the way for cleaning.

I took advice and bought a new bronze bush to replace the old needle roller bearing in case I damage it when drifting out the "figure of eight link" pin from the flywheel side (RHS/nearside) towards the carb (LHS/offside). Thanks for the tip about the engine casing buffer. I will make sure I remove it. The use of a G clamp around the engine lugs has been suggested as a way of taking the loading off the link pin bearings, so I will probably try that. It doesn't matter if I damage any paintwork as I extract the pin, but I will need to be very careful when I re-fit it, and the paintwork is new!!

In my original question at the start of this thread, I asked if the torsion bar was driven out from the flywheel side towards the carb side (LHS/offside). Thanks for confirming that's the correct way to do it.

[Big Al]

I have put together this diagram of the torsion bar assembly (see below), which I hope will be helpful.

[scootermad]

does any one know the sizes of the needle roller bearing for the torsion bar assembly