Clutch parts for fitting a Triumph Overdrive gearbox onto a 1970 Triumph Herald 1200

[johny]

Dave the thrust bearings are soft metal on top of a steel backing like the other crank bearings so once you go through the soft metal you risk damaging the crank surface (regrind required?). Also as the clearance gets bigger I think Im right in saying more oil flows so potentially reducing oil pressure in the rest of the engine....  

[DanMi]

plus if they do fall out (and they do) the chances of recovering the block are not that great and if the endfloat is enough to effect the clutch they may already have fallen out. My first experience of this was spending ages trying to get the clutch to work, just as Jagnut is here (I hope that I am wrong by the way)

[NonMember]

Well, I had a 2.5PI with enough end float to make the clutch over-sensitive to the slightest imperfection. When I dropped the sump and took the bearing cap off, both thrust washers were still in place and hadn't worn through. Fitting oversize ones fixed the problem.

On the other hand, my brother's first Spitfire had no particularly obvious clutch problems despite having completely lost both thrust washers. However, that was a coil spring clutch.

[johny]

I wonder if the crank can run in different places in different engines (no idea why) but if the crank runs forwards against the thrust, or whatever is limiting its movement, then the clutch operation wont change much. However if the crank runs at the back then pressing the clutch pedal will push it forwards making it feel strange....

[DanMi]

15 minutes ago, johny said:

I wonder if the crank can run in different places in different engines (no idea why) but if the crank runs forwards against the thrust, or whatever is limiting its movement, then the clutch operation wont change much. However if the crank runs at the back then pressing the clutch pedal will push it forwards making it feel strange....

It shouldn't be much difference as the thrust washers will be of the same or very close thickness and the tolerence is small 4-8 thou the problem occurs when the crank can move so when you press the clutch a lot of the movement is lost moving the crank forward, rather than operating the clutch, so long as the crank is held in place the clutch will work the arm will be tolerant of a little difference just not of for/aft crank movement

[johny]

yes thats what I mean. If the crank always runs in the forwards position the front thrust will wear but that wont affect clutch operation but if the opposite is true and the rear thrust wears then operating the clutch will feel different because the crank is pushed forwards onto the front thrust...

[DanMi]

The rear thrust is the most likely to wear, as the force on the thrust bearing is primarily when the clutch is engaged ie the clutch is pushing the crank forwards. The loading on the bearing is very low at other times, hence cars with auto gearboxes rarely have thrust bearing issues

[johny]

Makes sense so then Im at a loss to explain why some clutches seem to be affected and others not. I believe clutch action is quite dependant on relative angles of its components (eg. the problem with different thickness clutch release bearings) so maybe thats why some are changed more by thrust bearing wear....

[jagnut66]

Touching on clutch release bearings again for a moment:

Is it a sign of a worn one when you depress the clutch and you get a grating / grinding  sound (which is only present whilst the clutch pedal is pressed) but the gears still engage smoothly?

Best wishes,

Mike.

[Pete Lewis]

in general  yes 

the worst is if the crank thrusts have failed the flywheel fouls on the engine back plate when you press the pedal and it slows the idle  

hopefully it the cheap option 

Pete

[PeteH]

Only very slightly off topic. It there a known figure for the (acceptable) endfloat on the crankshaft of the 4 pot engines?. As an indication of thrust wear?.

Pete

[jagnut66]

16 minutes ago, Pete Lewis said:

in general  yes 

the worst is if the crank thrusts have failed the flywheel fouls on the engine back plate when you press the pedal and it slows the idle  

hopefully it the cheap option 

Pete

This developed this afternoon driving into Nottingham. Lots of lights, one way systems, mini roundabouts, low gear work (horrible place to drive round / into). Prior to that it was quiet, and quite liveable.

All seemed well on planet Herald, until......................

Getting fed up with dismantling it.

Plus the Morris is in my garage now and a replacement gearbox should be ready for it next week sometime (also to collect from Nottingham 😒), so the Herald will have to grin and bear it for a while, as I need a working car.

I will have to limit it's journeys I guess.

I have a spare prop now, so I will send that off to Dave Mac in Coventry and get a sliding one made up, may as well do that at the same time.

Best wishes,

Mike.

[Colin Lindsay]

Some Herald manuals say 0.004" - 0.008" as does the Service Training notes manual, for 6 cylinders 0.004" to 0.006", and after 1972 0.006" to 0.014" for both 4 and 6.

[DanMi]

4-8 thousandths of an inch is the correct service tolerance, but a worn engine will have a bit more and still be fine. If they fall out the crank grinds into the front main bearing cap  and unless caught early will render the block scrap. It may be possible to braze the cap and repair ( I have had it done). I have never had the flywheel grate on the backplate but that would be possible

A grating noise when clutch depressed could be a failed release bearing but isn't that new? 

[NonMember]

15 minutes ago, DanMi said:

grinds into the front main bearing cap

I expect you intended to type "rear" there. (No point scoring, just trying to avoid confusion)

[jagnut66]

37 minutes ago, DanMi said:

A grating noise when clutch depressed could be a failed release bearing but isn't that new

NOS -- so that could mean the grease inside had dried out unfortunately -- tell me about it. 

Best wishes,

Mike.

[DanMi]

29 minutes ago, NonMember said:

I expect you intended to type "rear" there. (No point scoring, just trying to avoid confusion)

yes I did you are correct, brain had a slight issue there

[DanMi]

8 minutes ago, jagnut66 said:

NOS -- so that could mean the grease inside had dried out unfortunately -- tell me about it. 

Yes it could, I threw one out as it was rough due to dry grease and continued to use the one from the clutch kit that was already fitted, though the cover wasn't smooth the bearing was fine. Unfortunately I have not found a way to clean and repack them. I would advise buying a 3 part clutch kit which will have the bearing though the plate will not work with the single rail box.

[Pete Lewis]

alignments of brg and fingers can make noises also finger design and brg contour all add up to areas of noise 

many years back in the 60s my bridemaids dad had a 1300 FWD with flywheel in contact  , we rescured the block by welding replacement 

lugs on the brearing cap a bit of fettling  to repair the worn down  lacations  to lock the thrusts again   it lasted over 100k  

but do stick to the simpler suggestions before you dive into  the more serious to fix ideas 

pete

[DanMi]

a very simple non invasive test is to watch the front engine pulley with the engine running whilst someone presses and releases the clutch. If you can see significant for and aft motion that is bad if hardly perceptible then you can eliminate thrusts as a problem 

[jagnut66]

As it was running reasonably well up till then my first port of call will be the bearing, unless I spot something more serious when I remove the gearbox...... again........

Best wishes,

Mike.

[jagnut66]

8 minutes ago, DanMi said:

a very simple non invasive test is to watch the front engine pulley with the engine running whilst someone presses and releases the clutch. If you can see significant for and aft motion that is bad if hardly perceptible then you can eliminate thrusts as a problem 

I've heard of that somewhere before, I will give it a go. As you say, a simple test.

Best wishes,

Mike.

[Pete Lewis]

you often geta dull clunk as the crank moves up if theres a lot of clearance (engine off)

so eyes and ears  is all you need  ha !

Pete

[johny]

Course in any test youve got to make sure the crank is against its back limit before pushing it forward😁

[DanMi]

38 minutes ago, johny said:

Course in any test youve got to make sure the crank is against its back limit before pushing it forward😁

your not looking at this stage to make an accurate measurement, just is the movement excessive, which if the thrusts have fallen out or are badly worn will be pretty obvious