Author Topic: Anybody with Twenty One / 3TA experience?  (Read 20055 times)

Offline antoni

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Anybody with Twenty One / 3TA experience?
« on: July 28, 2013, 09:17:20 PM »
A first post following my mate's advice that any knowledge can be had by asking on forums - AND after finding them a lot of fun.

Anybody know why my recently acquired '58 Twenty One's clutch basket wobbles and clouts the primary chain case cover?

It's my second British classic after the end of a long run of Japanese bikes. Maybe it wasn't wise to buy a non-runner even if it was 'all there'. The gearbox problem - the main problem - was just the selector forks being in the wrong way round, but other problems had crept in during the previous re-build.

To the point!

Its using a 4 spring clutch, has 1/4" dia 1/4" wide rollers and doesn't have a 'thrust washer'. The basket is a new one, the old well worn basket is in with the spares bag.  Anybody know what it should have in there?

wetdog

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Re: Anybody with Twenty One / 3TA experience?
« Reply #1 on: July 28, 2013, 09:39:59 PM »
yours has no primmary chain tentioner fitted ? sounds like wronge tapper on the hub centre

Offline antoni

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Re: Anybody with Twenty One / 3TA experience?
« Reply #2 on: July 28, 2013, 10:03:51 PM »
It does have a primary chain tensioner, but it shouldn't have!

The first Twenty-one models had no tensioner and a straight-up primary chain case oil drain plug (so I was told last week by a bod wot had one). The later models had the tensioner and a slanting drain plug so that you could put a screwdriver through the hole to adjust it. Mine has the straight up drain plug, I'm wondering whether to leave the tensioner in or not bother with it - as was the original design.

The taper on the gearbox mainshaft accepts the 'clutch back flange' happily enough. It's just that the rollers and the basket don't end up happy and solid as does a very similar arrangement in my Matchless G3LS...

wetdog

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Re: Anybody with Twenty One / 3TA experience?
« Reply #3 on: July 28, 2013, 10:20:01 PM »
it should have a thrust washer , have you changed the primmary cover in order to fit a tentionar ? triumph did not do this in 58 but said there chains where "pre stretched" latter they changed there minds , this is a 58 engine but with alloy barrels , when the clutch is fully assembled , springs etc are you saying it rocks on the main shaft ?
« Last Edit: July 28, 2013, 10:23:24 PM by wetdog »

Offline antoni

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Re: Anybody with Twenty One / 3TA experience?
« Reply #4 on: July 28, 2013, 10:43:50 PM »
Just checked the Swansea Log book, I was being lazy it's a November 57.

It came with a tensioner but I think it shouldn't have one  because it's early, and because it has a  primary cover without the slant access to adjust it. It does have the distributor as in your picture. Not been able to find much on the net showing them.

Just been out into the shed, it looks like an iron barrel, certainly different from the clearly alloy head. Sorry for the lack of certainty here.

I have a Haynes manual and a downloaded parts manual 'catalogue 4' both showing a 3 spring clutch with 'thrust washer'. But my downloaded Meriden 'Workshop manual' shows a 4-spring clutch which doesn't have that thrust washer. A 4 spring clutch is fitted, and the previous owner said he fitted a new clutch basket for it. The bike has not driven since.

It rocks on the rollers as far as I can tell. The mainshaft taper fits the 'clutch flange' ( my term) fine.

Should the rollers be quarter by quarter, or quarter by 6mm, and does it matter?


wetdog

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Re: Anybody with Twenty One / 3TA experience?
« Reply #5 on: July 28, 2013, 10:49:57 PM »
so when the clutch is fully assembled you can hold the outter basket and it rocks ? what is the engine number please
First 3TA with primary chain tensioner was fitted during 1959 for the 1960 models , first engine number H18392

Offline antoni

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Re: Anybody with Twenty One / 3TA experience?
« Reply #6 on: July 28, 2013, 10:56:22 PM »

Yes, fully assembled, seems to be working OK on the handlebar lever, and it rocks.

Engine and frame number H1340.

Looking forward to your comments on that. I'm grateful for your attention.

wetdog

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Re: Anybody with Twenty One / 3TA experience?
« Reply #7 on: July 28, 2013, 11:11:14 PM »
its interesting but with the springs in ive never had this , they do rock when the leaver is pulled in or clutch disengaged to reduce this fit the thrust
can you take a pic your bike is a early one   
1958 
Engine Frame Numbers H761-H5480
mine is H5465
 
 
 

Offline chaterlea25

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Re: Anybody with Twenty One / 3TA experience?
« Reply #8 on: July 28, 2013, 11:20:18 PM »
Hi
 Rollers should be 1/4 x 15/64 (6mm)
Yes vital to have correct ones

HTH
John

wetdog

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Re: Anybody with Twenty One / 3TA experience?
« Reply #9 on: July 28, 2013, 11:30:13 PM »
quarter diamiter by 6mm long , they always looked shorter to me , but i cannot remember the last time i bought any

Offline Rex

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Re: Anybody with Twenty One / 3TA experience?
« Reply #10 on: July 29, 2013, 08:45:06 AM »
Those rollers are not 6mm, a 1/4 or even 15/64 but 0.2345" which is roughly 15 thou under a 1/4". You need the correct Triumph spares rather than industrial 1/4 X 1/4 rollers as those will lock the clutch assembly. ("1/4 by 6mm"......   ::) ::))

There's no thrust washer (or ally barrels!)  on the earlier C range bikes, so either there's wear on the hub or the basket is a Taiwan Ebay pattern part and probably machined to a less accurate finished size than the old one just taken off.
The tensioner being there or not is irrelevant to the clutch "rocking". Does the clutch grip when you've assembled it?

Offline cardan

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Re: Anybody with Twenty One / 3TA experience?
« Reply #11 on: July 29, 2013, 09:45:16 AM »

6mm is about 0.236" and 15/64 is 0.234375", both very close to the figure given by Rex. I know nothing about this clutch but assume that there was some end float in the original so that the odd thou and a bit wouldn't be enough to bind anything. Unless 1/4" (0.250") long rollers have been used and one or more washers have been left out?

Very hard to help Antoni without having a look - correctly set up there should be essentially no wobble. The answer is to measure everything (bearing inner and outer and the rollers with vernier and micrometer) and inspect the bearing tracks under a bright light. The diameter of the inner track + diameter of rollers should be only 0.001" or so less than the inside diameter of the outer track (in the basket). Something's badly amiss if it can wobble enough to hit the primary case!

Leon

Offline antoni

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Re: Anybody with Twenty One / 3TA experience?
« Reply #12 on: July 29, 2013, 09:58:48 AM »
Thanks all.

The tensioner is indeed not relevant but someone asked about it - perhaps to 'place' the exact model.

From what I've seen it is a very early model.

The clutch does grip when assembled though did slip slightly when tightening the crankshaft rotor nut.

The basket might well be a Taiwan special. The rollers seem to fit quite exactly into their space. It's quite clear now that I need new rollers, but I'd have thought the incorrect wider rollers would have reduced the rock.

The question is what else is needed. The 4-spring drawing shows doesn't showa  thrust washer - and it has a 4-spring - and the three spring drawing does. I wonder if there's a mixture of the two on the bike

I know there's a limit as to how much help I can get by remote control and I'm probably about there now but thanks a lot for the advice.

Offline twolitre

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Re: Anybody with Twenty One / 3TA experience?
« Reply #13 on: July 29, 2013, 11:43:49 AM »
Without looking anything up I would think that talking millimetres for any dimensions except Bore x Stroke for a British bike this age is ridiculous. As far as I am aware all dimensions on British engineered machines were Imperial except that for some reason bore, stroke and capacity always seemed to be traditionally Metric worldwide except for the USA.
Certainly mixing 1/4 inches and 6 millimetre on the same item sounds rather strange.
I have a 1959 5TA which has no primary chain tensioner either. Because I have never been able to obtain a primary chain cover gasket to fit (which is different too) I have always had to make my own.
It has a three spring clutch which seems to be quite normal, though four spring clutches were also fitted on some.
By the way, that is the bike in my Avatar pretending (minus the bath-tub and plus a few 5T bits), to be a 5T!
Jim.
« Last Edit: August 01, 2013, 10:39:51 AM by twolitre »
Jim Walker.

wetdog

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Re: Anybody with Twenty One / 3TA experience?
« Reply #14 on: July 29, 2013, 12:01:53 PM »
I think 6mm is a few tho under a quarter , but as its on the length I doubt this is the problem , it moves that much to hit the primary something is wronge , maybe main shaft nut (kick started side) lose or bearing failed , difficult to tell with out seeing first hand , but it wont be much as these early 350 where very good and under stressed