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The shift plunger spring is available in different tensions. What is the reason for the stronger spring? What is the advantage?
As in the other recent thread - I'll be installing a 4 speed gearset in a T120RV mongrel motorbike. Mostly stock engine, not a race bike.
(Edit - this trans has been converted to plunger, originally had leaf spring).
Thanks
Al

Its to try to prevent jumping out of gear, I tried it and it made shifrting harder.

There are different length plungers to go with different length springs, and in the case of 5 speed, different housings too. IME, the depth of the counterbore for the plunger housing can vary too, in the process of coverting from 4 to 5 speed, I've had a plunger housing hitting the camplate! In general, the combination of plunger, spring and housing from any one of the parts books will be correct, I only use something different if, say, I'm using a late low inertia camplate in a 4 to 5 speed conversion, in which case I use the T160 combination

Get a small ball bearing, put it behind the spring to build more tension

I also polish the cam plate and "define" the valleys to obtain better engagement

Hi, The outside profile of cam plate changed when they went to leaf spring 4 speed.

This shape was kept thereafter. On both 4&5 speeds, with 5 speed having a extra notch of course.

Factory brought back plunger in ‘73. But plunger tip was repointed to match the leaf spring cam.

So far as I have seen, all the new reproduction cam plates are the later leaf spring profile. Again these need late plunger assembly, starting 1973. As Mick said, verify clearances for plunger.

It’s important that you have 4 speed shift shaft assembly & pawls, if you have 4 speed trans. Make sure shift shaft centers very reliably.


As Mick pointed out there are many little details. All these matter. If we had parts all laid next to each other the differences are easy to see, but you have to really look. Problem is at home most of us are looking a photos on internet that may or may not be correct. Parts sellers suggest lots of parts are interchangeable, when they are not. They might bolt up, but don’t really work right.

And they say Triumphs are simple!
Don

I saw an ad on eBay for front fender that fit all Triumphs from 1964 to 1978. Yeah. Caveat Emptor.

Who knew that it was so complicated? I have two '72 models, both 5 speed. My Bonneville from May has the leaf spring, my Trident from September has a plunger. I can only guess that they both have the same cam plate. I can also only guess that the spring and plunger on the Trident are as it came from the factory, both shift well but the Trident is the one on which I can't find neutral when stopped.
I have a '74 T150V parts book, but I can't compare parts as my '72 parts book shows only the leaf spring. However, the numbers for the cam plate are different, early is 57-4360, late is 57-4624.

Is there a 4spd leaf spring and a 5spd leaf spring? I have a XG 42xxx engine case without the shift plunger. Been having trouble getting the inner cover to seat properly. Maybe wrong leaf spring? I am attempting to convert from 4spd to the upgraded 5 speed gearset.

Who knew that it was so complicated?
Are we having fun yet? I sure am.

Hi, Make certain the inner (left side of trans) lay shaft thrust washer is still in place. If it comes off dowel inner cover won’t seat. Don’t force it or you can push dowel in. Then it’s big trouble.

The cam for 5 speed is same with leaf or plunger.
Don

The leaf spring is the same. Each of my parts books shows both gearboxes, but the spring is only shown in the diagram for the inner cover.
Indexing a leaf-spring gearbox can be tricky. It helps to rotate the cam plate a bit anti-clockwise so that the spring engages the correct notch upon entering and rotates it slightly into position.

Oh, I do see it now. They put the plunger and spring on another page. Different parts form '72 and '74.
Still, no telling what you'll get if you order either number these days.
"Fits 72 through 80"

Hello Noe, you did open out the inner cover bearing shield for the M/S 1st/ 2nd gear?

Thank you everyone. I dismantled the transmission this morning. I had locked it in 1st gear, causing to leaf spring to resist seating properly. It is a slide job!

I will try again tonight. I am right on the edge of putting it together correctly. Then I will take it apart and use the gasket. Yes, I am having fun.

Noe