my clutch has failed yet again

[willcolumbine]

yamaha_fizzy wrote:

that little crack in the housing wont make a difference will it ?

No - it shouldn't do! Those slave cylinder mounts always seem to have a little crack there. It's near imposible to get one without. I've tried!

[Fizzy]

thanks for the continued help, though i still cant pinpoint the problem. ive got a new bolt to use as a pin that is a perfect fit within the pivot holes, and it will eliminate any play. the release bearing runs fine. the first clutch i took out of the car slipped because the friction plate was worn down to the rivets. im 99% sure i took  diaphragm clutch out then. so that one had lasted long enough to wear through to metal.

is it possible the slave cylinder was so far in it was pushing the bearing too far into the diaphragm, and the marks are from the outer edge of the bearing ? might explain why the ring of marks is slightly larger than the bearing face ?

i've stripped the gearbox, and im going to replace 1 synchro ring, the 2 main bearings and possibly the 3/4 gear hub. though thats not too worn. i can see how it might get expensive, but i am relieved it looks a lot simpler than i anticipated inside a gearbox. the rest of the cogs and synchros look great, so other than a couple of new gaskets, thats all i need for the gearbox.

[thescrapman]

You should only need to push teh slave in as far as determined by the original slot that is now missing from your slave.

It will self adjust to suit.

If the slave was right in you will be over stretching the fingers.

The slot was removed to compensate for the missing pivot pin.

Look at an unmolested slave and go by that.

Cheers

Colin

p.s. synchro rings. Check the archives to find out if the new rings for your box are decent or shite quality. Can't remember which way round off teh top of my head. If they are the shite ones get a good secondhand one.

[CharlieB]

yamaha_fizzy wrote:

...im going to replace 1 synchro ring....

Don't use a new one they're cr*p, NOS only.
(Mine was a single rail box, is the situation the same for 3 rail?)

[Fizzy]

thescrapman wrote:

You should only need to push teh slave in as far as determined by the original slot that is now missing from your slave.

It will self adjust to suit.

If the slave was right in you will be over stretching the fingers.

The slot was removed to compensate for the missing pivot pin.

Look at an unmolested slave and go by that.

Cheers

Colin

p.s. synchro rings. Check the archives to find out if the new rings for your box are decent or shite quality. Can't remember which way round off the top of my head. If they are the shite ones get a good secondhand one.

thanks for that. i didnt know my cylinder had been cut until you mentioned it, i thought it was normal. it seems the flat area on mine is about twice as large as it should be. im now quite confident that my problem was having the slave pushed all the way in up to the edge of my 'modified' cut in the slave. pushing the fingers in far too much, and rubbing on the outer edge of the bearing ?

sound feasible ?

thanks for the info about the synchro rings. you havn't got any good ones kicking about have you ? ;D

[triumphspitfire.eu]

yamaha_fizzy wrote:

i've stripped the gearbox, and im going to replace 1 synchro ring, the 2 main bearings and possibly the 3/4 gear hub. though thats not too worn. i can see how it might get expensive, but i am relieved it looks a lot simpler than i anticipated inside a gearbox. the rest of the cogs and synchros look great, so other than a couple of new gaskets, thats all i need for the gearbox.

Hello Fizzy,
if your gearbox is noisy in first gear and reverse gear, I suggest you also substituted these pieces:

-Synchro-Hub Assembly (1st & 2nd Gear);
-Layshaft-gear cluster ;
-Reverse gear (even if in good condition!).

His gearbox will become silent (1 st speed gear and reverse gear).
Is expensive, but his gearbox is now disassembled.....
Synchro ring only NOS!

http://www.triumphspitfire.eu/pagine%20sito/I%20primi%20interventi/Pagine%20Meccanica/pagine%20revisione%20meccaniche/revisione%20cambio/sbarco.htm

Bye, Giuseppe PALMISANO

[Richard B]

yamaha_fizzy wrote:

ive got a new bolt to use as a pin that is a perfect fit within the pivot holes, and it will eliminate any play.

Considering you have it this far apart I would change the 'bolt' for the pivot pin kit from Canlys and put in new top hats.

[sparky_spit]

yamaha_fizzy wrote:

is it possible the slave cylinder was so far in it was pushing the bearing too far into the diaphragm, and the marks are from the outer edge of the bearing ? might explain why the ring of marks is slightly larger than the bearing face ?

I think, like others above, that you may well be right. Also, as you had a droopy bearing carrier, it would not have contacted the fingers completely concentrically. It may well have oscillated quite a lot as it pressed against the fingers creating the wear marks, noise and vibration?

Thinking about what Colin has said above re the extended slot; that all makes sense too. My unmolested slave has a slot that allows some fore and aft sliding and adjustment but not as much forward movement as your modified one!

[junkuser]

For the fingers on the diaphragm to be going so far forward as to allow the periphery of the thrust to make contact when declutching would suggest the diaphragm is too compressed in resting state.

A thicker driven plate could cause this.  Are there different thicknesses?

Are there measurements specified on how far out the fingers should sit when assembled on a new plate?

A photo of a pressure plate mounted with a new driven plate to show finger positions would be helpful.

[junkuser]

Were 3 rail gearboxes ever originally mated up with diaphragm type clutches?

Were the input shaft splines on boxes used with diaphragm clutches the same as on the earlier ones?

If different then an earlier driven plate could have been used in this case to fit the splines and it has been
suggested by Pete Lewis, the early plates are thicker so could account for the problem.

[drofgum]

Junkuser,
The input shaft stayed the same through the Mk1 & Mk2 Spitfire range. The diaphragm spring clutch was used in the Mk2.  I'm not sure if it was introduced with the Mk2; there is something in my memory that says late Mk1 cars had diaphragm clutches but the factory parts book shows the clutch change coming with the introduction of the Mk2.
Fizzy,
I think the "adjustable" slave cylinder is the culprit.
If using a used synchro cup check it against the gear it will work with. There should be a substantial drag when the two are wrung together. If there is little drag then either the ring is knackered or the cone surface on the gear itself is worn too far. I mention the second possibility as I once had that problem. A new synchro cup was not able to grip the cone on my 2nd. gear and the only cure was a new gear. More likely you will find that replacing the synchro ring will cure the shifting issues you describe.
If you use a bolt as the pivot pin make sure the threads aren't in either the top hat bushings or in the release arm; in either place they will act as a file wearing away at the part they contact. Cutting the threads off a long bolt works fine, and of course the head of the bolt keeps it from dropping out as the factory pivot pin does once the crinkly piece breaks up in the release arm.
Getting the main bearings off of the shafts will require a puller; putting the new ones on will require a press or something that can act as a press. Don't try to put them on with a hammer, the shock of the hammer blows will cause the balls to indent the races. Result: noisy bearings.
Synchro rings for 3rd. and top gears are easily replaced once the shaft is shifted rearward. the 2nd. gear ring is more difficult as you have to remove the circlip retaining the gears on the mainshaft which isn't as simple as one would like.
                                                               Sorry about the long post,
                                                               Paul

[junkuser]

Thank you Paul.

[Pete Lewis]

cant find the diapragm disc thickness but a coil disc is 0.305" lightly compressed (nip the facings in a vice ) and then mesure
diaprhagm disc are generally about 1mm thiner,  this would make the fingers underflush when clamped up instead of
just proud , you dont want to compress a diapragm beyond the fingers being parallel.
  finger /throwout  travel would be around 1/4"   Pete

Gearbox,  if its stripped make sure you fit new sliding sleeve detent springs (3 in each hub) they are important part of sychro operation as is the flank face of the sleeve and baulkring dog teeth chamfers ,dont want these to be chimbled up , just nice flat chamfers, it is these chamfers that transmit the pressing load to the baulkring,

tip ....to fit new balls and springs do it in poly bag then you catch them as they escape...  ping
if the springs are weak and the chamfers stuffed then you get a clash,crash halfway thro'a change  as the ring is let go early  Pete

[Jason]

I'm thinking your problem is in the release bearing pivot and slave mounting, put the right pivot mechanism in and set up the slave position so you can see what's going on when you press the pedal. You might find it easier to do all this once you've degreased it all - it's amazing how different gearboxes look when clean (of course it's only temporary as they are self soiling!)

[sparky_spit]

In a perfect world, what you need is an inspection hatch in the bellhousing (like what you get on a a Mini's A series) so you can actually see the release bearing and it's operation in action.

[Fizzy]

just how bad are the synchro rings from canleys ?

i want to be putting my car back together at the weekend, the only thing stopping me is waiting for the bits to go in the gearbox. other than that its just a case of putting everything back together. so really, unless i can get some NOS or good S/H synchros in the next day, it looks like my choices are either buy a new one from canleys or stick with my worn one.

[heraldcoupe]

All three synchros are the same, a box with a worn 2nd gear synchro will often yield good synchros from 3rd and 4th gears. While scrap gearboxes are plentiful and cheap, that doesn't help unless you can get your hands on one imminently.
At a push, use the best synchro you have on 2nd, the next best on 3rd, with the worst on 4th. The 2nd is the hardest working synchro, while a worn 4th synchro is easiest to live with.

Not much help with where you are, but if you want to collect them from Wiltshire you are welcome to a handful of dead gearboxes, free of charge.....

Cheers,
Bill.

[Slimboyfat]

yamaha_fizzy wrote:

just how bad are the synchro rings from canleys ?

.

Yes pray tell!

[thescrapman]

That was a bit unfair singling you out!

But then I guess he will be purchasing the parts from your good self, I suspect that they are universally available.

I am sure you would not sell one of the "iffy" ones without warning the nice young gentleman... :-)

So is it the 3-synchro ones that are iffy??? Would / Could you sell him a good secondhand one if he asked?? Or are they now the proverbial Hens teeth?

Cheers

Colin

[Deleted User]

My understanding of modern versus NOS synchro rings.....

I believe that the modern manufacture rings are gripped in a chuck during machining - which has three points of contact with the ring, and can cause very slight distortion in its shape.  When the material is relatively soft, this can result in very slight tri-lobular shape when the item is removed from the chuck.

I believe that the original rings were gripped in a collet during machining, which has even pressure contact around the entire ring, so when removed from the machine it remains totally round.

[willows40]

is it just me or does the bearing carrier look to long, also got a 1500 gearbox sitting here doing nothing

cheers andy

[Richard B]

Slimboyfat wrote:

Yes pray tell!

I thought the small box synchros were ok, but the quality of the after-market big box synchros was suspect.

and not singling out any supplier, just the state of the market.

[Fizzy]

Slimboyfat wrote:

Yes pray tell!

hi, apologies for making it seem im criticising you, far from it. i have already actually put my order in due to time constraints and have ordered synchro rings and a few other bits and bobs from you yesterday. earlier on it was mentioned that basically all 'pattern' synchro rings were rubbish and i was better off finding NOS or second hand. i only mentioned your place at it was where i always planned on ordering from. i also assumed that most retailers get their synchro rings from the same supplier. i might be wrong though ?

anyways, sorry again. i've never been dissappointed with anything from you, but obviously when people with far more experience than me with these cars speak up and say new synchros are rubbish, i can't afford not to take note. sorry for any confusion

jason

[Jason]

The trouble with emotive statements like "new repro syncro rings are crap" is that it's both true and false - yes some repro syncros for some gearboxes have been shown to be less than perfect at some time, in some applications. Of course that's not as catchy as the first statement!
There definately are some dodgy repro syncros out there, I've got a set here, when I took them to be built into my gearbox I enthusiastically handed them to the builder who, just as enthusiastically handed them back to me and said I could keep them, he'd use his own.
Someone like Canleys who not only sell but also build gearboxes will know what works and what doesn't, no one wants warranty work on gearboxes and I know Dave has done a lot to get the best components and the best labour into his boxes.
Remember, not all syncro rings are created equal. NOS is good and often preferable to repro but be careful, there is apparently NOS stuff out there that's sat on shelves for years because it's defective! Also, repro from 20 or 30 years ago can often look like NOS. I doubt you'll find much true NOS for gearboxes - think how many boxes have been worked over and over long after production ceased.

[Slimboyfat]

yamaha_fizzy wrote:

hi, apologies for making it seem im criticising you, far from it. i have already actually put my order in due to time constraints and have ordered synchro rings and a few other bits and bobs from you yesterday. earlier on it was mentioned that basically all 'pattern' synchro rings were rubbish and i was better off finding NOS or second hand. i only mentioned your place at it was where i always planned on ordering from. i also assumed that most retailers get their synchro rings from the same supplier. i might be wrong though ?

anyways, sorry again. i've never been disappointed with anything from you, but obviously when people with far more experience than me with these cars speak up and say new synchros are rubbish, i can't afford not to take note. sorry for any confusion

jason

No offence taken, don't worry about it, retailers (of all sorts) become by nature thick skinned!

Be wary of the closet exspurt that pops up on forums with advice such as such and such repro part is rubbish, and always has been.

Classic car parts supply is fluid, and manufacturers, suppliers, and importers can change regularly. For instance in the course of last year a common wearing part that we sell hundreds of changed it's initial source/quality three times even though we bought it in from the same wholesale outlet. At every juncture there were 'issues'with it. We were left to sort them out even though we weren't warned that it had changed. Spread that across several thousand part numbers, and as you can imagine it keeps us on our toes.

The same is true on syncro rings, and today's advice on quality is just that, today's! Multiply that across the trade, and as you can see it's hardly fair for the self appointed expurts to pop up with a coverall 'avoid such, and such because it's no good'. Yesterday they might have been no good from supplier X, but tomorrow they might be excellent from supplier Y, or the whole trade come to that.

Take the smaller of the small gearbox syncro's (Herald, Spitfire I-III, Vitesse/GT6 I-II). In 2008 we were selling what I thought to be a good quality reproduction item. Sometime early last year it became temporarily unavailable. Fortunately I managed to find some Stanpart stock to tide us over for most of last year. Recently a good reproduction syncro has become available again just as the Stanpart ones ran out! So in the course of just over 12 months supply has changed three times.

The larger of the two small gearbox rings (Spitfire MKIV-1500, GT6MKIII etc) is another matter. As far as I'm aware there has only been one source for these in recent years. It's not the best quality, but it's all there is. We try and make customers aware of this when they enquire. My suggestion has always been to use these on 1st, or 4th, and use one of the best original rings from your box on 2nd, and 3rd (usually the ones off 1st, and 4th!).

There it is straight from the proverbial horses mouth. However please remember that this is today's advice. If at any time in the future you should want to buy anything from anyone ask them/us for their/our advice. Most if not all traders do their level best to maintain the best available (and that's the important bit) quality stock.

Sorry for the long winded answer.