Classic British SparesKlempf British PartsBaxter CycleBritBike Sponsor SteadfastCyclesSRM EngineeringLucas Classic MotorcycleHepolite PistonsIndustrial tec supply

Upgrade your membership to: Premium Membership | Gold Membership | Life Membership | Vendor Membership | Site Sponsor Membership
Welcome to BritBike Forum!
Britbike forum logo
Member Spotlight
Brad Jones
Brad Jones
Mayenne
Posts: 29
Joined: October 2017
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Previous Thread
Next Thread
Print Thread
Joined: Aug 2019
Posts: 24
T
Britbike forum member
OP Offline
Britbike forum member
T
Joined: Aug 2019
Posts: 24
1960 T100A which is 1959 build and is a unit 500, but it has many pre-unit parts because it's an early bike. It has the 4 spring clutch, early distributor, etc.

I'm having a lot of trouble shifting. The 1-2 shift isn't too bad but not great, the 3-4 is pretty good, but the 2-3 has a false neutral and is horrible. I basically have to shift into that neutral, then try shifting again. Shifting directly results in a horrible clatter of the gear being rejected, which to me sounds like those dogs being rounded off. The bike also has a terribly stiff clutch despite going through everything, and I wonder if that led the previous owner to chew up the gears.

I've had the parts out that don't require removing the transmission shafts, and I can't tell which parts need replacing. They're far too expensive to just replace everything.

Edit: I'm told that the inner and outer trans covers shouldn't have gaskets, but then why do the gasket kits I find have them, including vintage/NOS gasket sets and modern kits like Steadfast? Could this be causing some of the trouble?

Questions:


  • Is the 2-3 false neutral normal on these old British bikes?

  • Which dogs exactly would be worn to reject a 2-3 shift? Bonus points if you can give the part numbers so I'm sure to know which ones you mean.

  • Is there any solution like undercutting that could get these by for a while? I don't put much mileage on the bike, and I don't need to ride or shift hard or fast, just reliably.

  • Could anyone help me source these parts? I'd really prefer to switch to a wide ratio gear set if it didn't cost too much more, but finding parts here is difficult and very expensive. ($1300 is what I found online for NOS parts)

Last edited by The Momes of Wrath; 07/07/20 9:41 pm.
Support Your #1 BritBike Forum!

Check out British motorcycles for sale: British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Joined: Nov 2012
Posts: 1,913
Likes: 45
K
Britbike forum member
Offline
Britbike forum member
K
Joined: Nov 2012
Posts: 1,913
Likes: 45
"The bike also has a terribly stiff clutch"

" it has many pre-unit parts because it's an early bike. It has the 4 spring clutch"

These 2 statements make me think the problem is much more likely to be clutch related.

I'm no expert on early C range bikes but I believe all unit Triumphs were 3-spring clutches, so if yours has a 4-spring then it is using at least a pre-unit shock absorber and pressure plate.
That in itself is not hell and damnation, as long as all the right bits are fitted.

My pre-unit uses 4-spring with duplex unit stuff, so I know it can work just fine.

I think you need to dismantle your clutch and see exactly what you have. At the very least you need to spend some time setting the 4 springs for even plate lift - slacken the spring nuts and start from scratch.

Hopefully the gearbox is not your problem!

Joined: Aug 2019
Posts: 24
T
Britbike forum member
OP Offline
Britbike forum member
T
Joined: Aug 2019
Posts: 24
>I'm no expert on early C range bikes but I believe all unit Triumphs were 3-spring clutches
Only from 63 up or so. 1960 was definitely 4 spring on a unit trans.
Edit: Part change was through 63 and 64-up, so 60-63 and all pre-units had the 4 spring. 64-up had the 3 spring. I still want a hub from one of those to finish my upgrade and reduce wobble...

>setting the 4 springs for even plate lift - slacken the spring nuts and start from scratch.

Did that a dozen times by the book, tighter, looser, everywhere in between with not much discernible change. Same with clutch adjuster and the cable routing. No change. Yes, the lever is correct as well. Nothing binds until the springs are tightened down.

Last edited by The Momes of Wrath; 07/08/20 2:48 am.
Joined: Oct 2003
Posts: 4,065
Likes: 9
D
Britbike forum member
Offline
Britbike forum member
D
Joined: Oct 2003
Posts: 4,065
Likes: 9
The clutch spring adjusting nuts should end up just about flush with the ends of the threads to work properly.

When you put the bike in first from neutral with the engine running is there a big grind? Does the bike try to creep forward with the clutch lever pulled to the bar?

I know you have a 500 but my 650 does have a "neutral" between 2 and 3 because I sometimes accidentally put it in to it at a stop. In normal riding when changing I don't have to move the lever twice to change from second to third. Extremely rarely when changing from third to fourth, when doing a too hurried change, it slips into another "neutral". Generally it works perfectly normally.

As Koan says gearbox troubles are almost always to do with the clutch.

As to gaskets in the gearbox my 1958 3TA which is a similar bike to yours didn't have them.

Dave

Joined: Aug 2019
Posts: 24
T
Britbike forum member
OP Offline
Britbike forum member
T
Joined: Aug 2019
Posts: 24
I should have been more clear - I have to try to hit the 2-3 neutral and then shift into 3rd if I want to avoid most of the clashing. It's also much easier to hit neutral there than other gears if I don't shift firmly enough.

It doesn't grind into 1st or try to creep. The clutch doesn't seem to be dragging. The Manual specifies: "Screw down the nuts so that about 1/8 in. (3.2 mm) of the pin shows through".

Joined: Nov 2012
Posts: 1,913
Likes: 45
K
Britbike forum member
Offline
Britbike forum member
K
Joined: Nov 2012
Posts: 1,913
Likes: 45
Hi Momes,

I wasn’t aware of the 4-spring clutch on the pre-63 unit C range.

Now you’ve mentioned it, it does make sense as I guess they’d use the same parts as the concurrent pre-units till 1962, when the 650s went unit with 3-spring clutches for 63.

Does yours use a single or a duplex primary chain?

Does the shock hub have a lip at the back to hold the first plate (a plain one) or is the shock hub without the lip (and so takes a friction plate 1st?)

If the latter, does it have a thrust washer behind the basket, and corresponding hub with a recess to accommodate it?

As I mentioned, on my pre-unit I have employed unit duplex components, but have retained the 4-spring shock hub (with the lip ground off) and pressure plate. It works just fine, no logical reason why it wouldn’t.

Joined: Aug 2019
Posts: 24
T
Britbike forum member
OP Offline
Britbike forum member
T
Joined: Aug 2019
Posts: 24
Duplex from the factory for the unit 500s, lip on the cush because it uses the pre-unit clutch, no thrust washer on the 4-spring models. The parts Manual shows plain steel first and last. 6 plain steel, 5 bonded friction discs between, so that's what I was running.

Joined: Nov 2012
Posts: 1,913
Likes: 45
K
Britbike forum member
Offline
Britbike forum member
K
Joined: Nov 2012
Posts: 1,913
Likes: 45
Thanks, so a curious blend of the wobbly p/u clutch with duplex drive.

But you say it doesn't drag (as illustrated by no crunch into 1st from neutral) so I guess it works well enough and is unlikely to be the cause of the gearshift issue (unless the wobbliness becomes exaggerated at higher rpm).

I'm afraid that's the limit of my thoughts - best of luck Momes.

Joined: Oct 2003
Posts: 4,065
Likes: 9
D
Britbike forum member
Offline
Britbike forum member
D
Joined: Oct 2003
Posts: 4,065
Likes: 9
If you have exhausted the clutch idea then you would just have to get in the gear box and check the cam plate and the fit of the forks in it. Also the forks themselves. Could it be the lever return springs? Also, have you got enough oil in the gearbox? Worn dogs on the gears would just cause slipping out of gear, I think. They wouldn't make gear changing difficult. The dogs on my 650 gears looked a bit worn but the gearbox still works fine.

Last edited by dave jones; 07/09/20 9:41 pm.
Joined: Aug 2019
Posts: 24
T
Britbike forum member
OP Offline
Britbike forum member
T
Joined: Aug 2019
Posts: 24
Good to hear about the dogs if you're right. I read adding a gasket can change shifting a lot so I might try sealing without them. Gear oil was ok, but I can't keep a portion of it from crossing to the outer cover. Return springs are new and work fine.

Cam plate was replace with a used one that is... I think acceptable. Much better than what came out of it. Forks seem to fit well but I don't know how to check them other than looking for obvious damage, which I didn't see.

Joined: Apr 2014
Posts: 304
Likes: 6
Britbike forum member
Offline
Britbike forum member
Joined: Apr 2014
Posts: 304
Likes: 6
Originally Posted by The Momes of Wrath
1960 T100A which is 1959 build and is a unit 500, but it has many pre-unit parts because it's an early bike. It has the 4 spring clutch, early distributor, etc.....

Edit: I'm told that the inner and outer trans covers shouldn't have gaskets, but then why do the gasket kits I find have them, including vintage/NOS gasket sets and modern kits like Steadfast? Could this be causing some of the trouble?

Questions:


  • Is the 2-3 false neutral normal on these old British bikes?

  • Which dogs exactly would be worn to reject a 2-3 shift? Bonus points if you can give the part numbers so I'm sure to know which ones you mean.

  • Is there any solution like undercutting that could get these by for a while? I don't put much mileage on the bike, and I don't need to ride or shift hard or fast, just reliably.

  • Could anyone help me source these parts? I'd really prefer to switch to a wide ratio gear set if it didn't cost too much more, but finding parts here is difficult and very expensive. ($1300 is what I found online for NOS parts)

RE gasket: Some say a gasket can fix gearbox problems but the bikes didn't come a gasket and the inclusion of one, in my opinion, is unlikely to have any effect on the vast majority of gearbox problems.

RE false neutrals: The older style camplates have neutral notches between all gears. Newer part eliminated all but between 1st and 2nd, but you can still hit a neutral between other gears if you try because there's a wide segment between the notches for the gears. You can see the old and new camplates side by side on this page:
www.hermit.cc/tmc/bb/2015/wtd_2/index.htm (scroll down left side and click on thumbnails of camplates).

RE which dogs shifting between 2nd and 3rd: You can figure this out by clicking back and forth between the photos for 2nd and 3rd gears on this page:
www.hermit.cc/tmc/technote/gear_cluster/back/index.htm
or this page:
www.hermit.cc/tmc/technote/gear_cluster/front/index.htm

When you shift from 2nd to 3rd, you're engaging the mainshaft third gear with the dogs on the mainshaft low gear; and the layshaft third gear's dogs with the layshaft low gear.

RE:expensive parts sourcing: It's very unlikely that you need a bunch of spare parts to fix this problem. Very likely there's one bad part. Find it and replace it.

You could replace the whole gear cluster and still have the same problem.

If it's not a clutch problem then I'd be looking at the outer gearchange quadrant and the stops in the outer cover. Or possibly the shifting forks.

For more info, see:
www.hermit.cc/tmc/om/manual.htm#gearbox
and
www.hermit.cc/tmc/technote/gearbox/index.htm


Bruce Miller
aka The Hermit
The Bonnie Ref: https://www.hermit.cc/tmc/om/manual.htm
Joined: Aug 2019
Posts: 24
T
Britbike forum member
OP Offline
Britbike forum member
T
Joined: Aug 2019
Posts: 24
Hermit, Thanks for all of that. I had trouble finding that site with the images. The transmission is different, but yes it looks like my 3rd gear problem might be the worn dogs on the mainshaft 3rd gear. They look worn about twice as much on the forward corner as on the back. The back is about the same as the similar dogs on the layshaft gear.

It looks like my mainshaft and layshaft are beyond tolerance on the ends though, so I'm not sure what to do. They have a nice polish, no scoring, and otherwise seem usable but I don't know of any oversized bearings for them.

Yes, it's expensive. A single gear here is half a day's pay for me, plus I'm disabled without any income. A layshaft or mainshaft is going to be a week's pay each. That's in addition to bushes, machine shop for pressing bearings, and probably getting the head done. I just hope and pray there's enough valve seat left to allow cutting for new guides. Valves and guides look to be about $100 without labor.


Moderated by  John Healy 

Link Copied to Clipboard
Job CycleBritish Cycle SupplyMorries PlaceKlempf British PartsPodtronicVintage MagazineBSA Unit SinglesBritBike SponsorBritish Tools & FastenersBritBike SponsorBritBike Sponsor






© 1996-2021 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5