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#564184 09/20/14 9:15 pm
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I'm fairly new to Gold Star ownership having bought my Goldie from a USA seller.It did need a bit of work to sort it out,mostly top end,wiring (it didn't have any) and GP carb issues.I took it out on my local classic bike club rally yesterday and had a bit of a problem with the gearbox.It was working fine until it got hot after about 70km (It was a 30 degree C day).The box stuck in 4th gear and wouldn't change down using my foot,a bit of work with my hands got it into neutral whereupon it shifted back through the gears into 4th again but it then started jumping out of gear every few hundred metres and then sticking in whichever gear I was in.After the bike had stood for a while and cooled down things improved but not back to normal.Sounds like it could could be a lubrication issue even though the box was filled to the correct level,it could also mean wear on the shafts,bushes etc etc.The bike is a 1956 model with a 1961 engine.I think the gearbox is original and is stamped RRT (with no 2) so I presume it doesn't have the Torrington bearings on the shafts,is this right for a '56 model?Is it possible to modify the case to take Torrington bearings?If anyone has any ideas about this problem I would appreciate any feedback before I pull the box apart so I've got a bit of an idea what to look for and if I can modify the case for Torrington bearings.

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Trog: The T should mean that the layshaft has the needle bearings. A 2 would mean it also had the needles in the A gear for the mainshaft.

What were you using for lubrication in the gearbox?

Gordo


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.........
You MIGHT want to pay attention to where the detent plunger is, in relation to the shift ..."drum"? Wheel?

You may want to pull the detent assembly and look at how full of crud the hollow threaded shaft might be? See if'n the spring is broken?

If that still doesn't help you figure out if these are/were your problem, I'd say you'll need to disassemble and clean all the components, check that the shift forks move easily on the guide shaft, the dowls aren't burred or have flattened areas, and the shift "drum"/wheel tracks do not have deformed tracks, and that it spins freely on the stub it turns on, with no burrs or sticky spots, or dirt caught inside the travel area. Without the detent in place.

Yes, any trans that is still correctly assembled, if it has a "T", the lay shaft SHOULD already have the Torrington needle bearings. On both ends.

You might check the shifter shaft the lever clasps, that the springs on it aren't broken?
Is the little "C" clip that holds the shift shaft correctly in place in the outer cover in it's groove?

I had one pre-unit trans, that when I took it apart, the "oil/lube" was just about to the point of being mud.....

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Thanks for the info guys.the problem definitely gets worse when the motor is hot.After the ride the other day when this problem arose the bike stood overnight and when I rode it home the next day the gears shifted fine untill I had done about 50km when the problem came back but not quite as bad.Gordo,I am using one pint of 20/50 engine oil in the gearbox as per the Manual.I reckon I have to strip the box and check it out.

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You can upgrade the oil to a 90W EP90 oil which will protect the gear teeth better and go another step to a fully synthetic 90W gear oil, if 90W is not available then 80/90W is fine.

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I don't have it here in front of me, but IIRC the Manual I read calls for 50 weight oil, which is what I have been using.


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The Manual was written before EP gear oils had been developed, if you look at the BSA and Triumph handbooks in the 60's as the years move on they drop 50W and change to EP90 on gearbox oil recommendations. 90W gear oil is the same viscosity as 50W engine oil so as an oil it gets where it needs to in exactly the same way, the difference is the additional additives that give it the EP or Extreme Pressure bit, these protect the gears on the contact points. Same as the monogrades engine oils which changed to multi-grade again as they became available.

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The original 1955 BSA handbook I have has a chart for summer/winter and 'overseas' machines.

In general summer calls for 50 weight for both the engine and gearbox. The gearbox needs 14 fl oz or 400cc. For winter it calls for a 30 weight. Multi grades and real gear oils are not mentioned. I can only guess what a UK winter or summer might be.

While I would use a gear oil like 90W or 80/90, I do not think that the oil being used would cause the problems you are having. The jumping out of gear sounds like something is really wrong. If the shifting bits were just stiff the box would just stay in the gear selected. Once in a gear a good box will want to stay in that gear until 'forced out' by pressure from the shifting mechanism.

The pre-unit box is much heavier than the unit BSA boxes in the shifting bits so I think you will need to have a look inside.

Gordo


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Trog;Before getting to deep into the "tear it apart" I would have a good look at the primary chain tension,it is meant to be 1/2 inch total up and down slack as checked through the inspection cover hole.If it is tight it makes gear selection really tough once the engine/gearbox assembly get to full operating temperature.I usually set mine to 1/2 inch plus a bit as I found that with it set at 1/2 inch once things were hot I couldn't get it to down shift smoothly,I have alloy engine and gearbox mounting plates,and once hot the 1/2 was gone and the primary chain was tight as a guitar string,I reset it to 5/8inch and it has been good since .Once you adjust the primary chain you must re-check the drive chain tension .If the adjustment on your primary chain is good then I would check the chain alignment from the clutch wheel to the engine sprocket.I'd do this before any major tear down,unless of course there is metal debris in the oil.I run straight 50 Kendal in both the engine and gearbox with good results and high mileage.

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So far Johnnies idea is the only sensible one here. Blaming the type of oil is a novices idea!

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Quote
Blaming the type of oil is a novices idea!


Read my post again, where do I say the oil will cure the problem ?

I said it was a useful upgrade not a cure.

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Wasn't specifically directed at you. Everyone else started going on about oils and you too.

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Thanks for that tip Johnnie,I'll check out the primary chain tension and see if that could be the cause of this issue.

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Trog ... An idea for you... Some years ago I had strange shifting issue with my Goldie. I was out riding those fine CA Twisties with some friends and I had great difficulty shifting. A knowledgeable GSr friend quickly spotted the problem. The rod that supports the shift forks had moved out of place as I had failed to properly tighten the grub screw the last time I had the tranny apart. aargh.

A quick way to spot this problem is to look at the end of the rod in the main tranny case 'hidden' behind the inner primary cover. The end should be flush with the case. The grub screw should be locked in place with a smear of gasket sealer over the head. Don't use Lok Tite! The sealer can be scraped away allowing you to use a long slim screw driver to loosen/tighten the screw.

Knowledgeable tuners replace the straight slot grub screw with a socket head grub screw. This allows you to use a long 'ball ended' allen wrench to get to the screw from underneath the bike.

Last edited by dave - NV; 09/27/14 2:10 pm.

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When checking pri chain tension turn the chain till it is at its tightest then adjust it.


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That does not help. Need to put pressure on the REAR chain then adjust the primary chain. If there are tight and loose spots in the chain, fix it.

Ron

Originally Posted by geordie
When checking pri chain tension turn the chain till it is at its tightest then adjust it.


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