Malcolm Clarke Posted March 31, 2017 Report Share Posted March 31, 2017 Hi, Suffering from the deaded sticky clutch when hot. Having looked at the forum suspect it might possibly be missalignment of the bellhousing to the engine back plate. I thought there should be 2 x 3/8" "alignment" bolts one at 2 oclock the other at 8 oclock. However no sign of the thicker 3/8" one at 8 oclock. Nor any sign of the back plate or bell housing ever having a hole large enough to accept this bigger bolt. (although the existing 5/16" bolt is a bit of a sloppy fit). All the holes are the same size accept the 2 oclock one and the starter hole bolts. Should all TR6 have this 8 oclock 3/8" bolt.? Not sure where to go from here. Drill 8 o clock hole to accept a 3.8" bolt. ? Loosen all bolts, nip up again, run engine for a bit, depress clutch a few times, and re tighten bolts in the hope of self-alignment,? Quote Link to post Share on other sites
Austin Branson Posted March 31, 2017 Report Share Posted March 31, 2017 (edited) Hello Malcolm, I had a stucky clutch, it was not an alignment problem, but wear on the release bearing carrier. Its a tube of steel that goes over the input shaft to the gearbox. I got a new one from TR Enterprises, and some 'special' grease, and no problem since. It's not easy to see the bolts, nor the alignment studs. I doubt that they are the problem. Gearbox out, I'm afraid. Let us know how you get on. Do NOT drill holes! Austin Edited March 31, 2017 by Austin Branson Quote Link to post Share on other sites
barkerwilliams Posted March 31, 2017 Report Share Posted March 31, 2017 (edited) Malcolm, If you don't have any bolts could I take the liberty of suggesting that you buy a set of these http://www.ebay.co.uk/itm/5-x-3-8-UNF-Bolts-Hex-Head-Cadmium-Plated-Length-1-7-16-Part-NAS6606-14-W10-/162039126427?hash=item25ba48d99b:g:PwoAAOSwnDxUcyZZ They are NAS6606 bolts if you look up the specification you will see that they are certified aviation bolts. They will be exactly the right size, to fit tightly and smoothly, they will not be a loose fit nor over tight. As you believe you have an alignment problem these will put you mind at rest. They are not 3/8 bolts, they are exactly 3/8 bolts! You will not need to drill a hole out they will fit. Alan No connection with the seller. Edited March 31, 2017 by barkerwilliams Quote Link to post Share on other sites
RogerH Posted March 31, 2017 Report Share Posted March 31, 2017 Hi Malcolm, I had a sticky clutch on my 4A last summer and it was a pain trying to solve. Eventually I found a very slight wear mark (0,0005") on the underside of the steel tube that holds the bearing carrier. This was caused by the bearing carrier digging in and causing the 'stickyness'. This in turn was caused by the above steel tube not being concentric with the splined input shaft of the gearbox. It was only 0.015" adrift (vertically) but enough to cause utter chaos. I made up a tapered shim to fit under the body of the steel tube to realign the tube/shaft. Roger Quote Link to post Share on other sites
John Morrison Posted March 31, 2017 Report Share Posted March 31, 2017 +1 for alignment issues, certainly the way to go before pulling the box. John. Quote Link to post Share on other sites
Malcolm Clarke Posted March 31, 2017 Author Report Share Posted March 31, 2017 To clarify: My problem is I do not appear to have a hole at 8 oclock large enough to take a 3/8" alignment bolt. Not that I do not have a 3/8" bolt in "stock". (alignment or otherwise). ..................Just noticed that gearbox has CC stamped on it, not CP Quote Link to post Share on other sites
RogerH Posted March 31, 2017 Report Share Posted March 31, 2017 Hi Malcolm, have you got #117 Dowel Bolt http://www.moss-europe.co.uk/shop-by-model/triumph/tr5-6/clutch-transmission-drivetrain/gearboxes-components/gearbox-units-external-components.html There are two required Roger Quote Link to post Share on other sites
Malcolm Clarke Posted March 31, 2017 Author Report Share Posted March 31, 2017 Actually I was in the process of pulling the box out. Got to the point of releasing the lower bolts when I discovered that it appears neither the bell housing or the back plate ever had a 3/8" alignment bolt at 8 oclock. And without drilling out existing hole would not ever take this "larger" size bolt. Then remembered reading that missalignment might cause the stckyness. ( I dont quite understand why, but there we are) Think I might try a bit of readjustment of alignment before struggling to remove the box completely. Quote Link to post Share on other sites
barkerwilliams Posted March 31, 2017 Report Share Posted March 31, 2017 (edited) Malcolm, On my gearbox the "correct" holes are not much larger than the smaller ones. The smaller bolts have a hole slightly larger than the bolt so fixing bolts fit easily with fingers and have play. The two alignment bolt holes are a tight fit and may need to be, I think the term is drifted in, not hammered just eased with the gentle assistance of a hammer. So that when it is in there is absolutely no lateral movement at all, not even a nats. The holes are not as large as you would expect for a "normal" 3/8 bolt, after all it has an alignment purpose. Alan Edited March 31, 2017 by barkerwilliams Quote Link to post Share on other sites
RogerH Posted March 31, 2017 Report Share Posted March 31, 2017 Hi Malcolm, the stickyness can be caused by a misalignment of the bellhousing to block. The bearing carrier and clutch cover need to be well aligned. if the steel tube that has the bearing carrier sliding on it is out of alignment then the following happens. The release bearing is pushed forward onto the clutch cover fingers. The fingers become concave and the release bearing is convex. The bearing sits inside the concave fingers - the problem is the concave fingers are on the centreline of the crank but the gearbox isn't. When the clutch pedal is lifted the release bearing tries to come back inline with the engine/gearbox but because the gearbox is not aligned it allows the carrier to cock slightly to get back to it's previous position - eventually the carrier will start to dig into (8 weeks in my case) the steel tube the carrier slides on. When it digs in pressure is removed from the release bearing (the slave cylinder is returning to its off position). However it doesn't stay there long and the release bearing tries to catch up with the footpedal etc and it all goes bang. Roger Quote Link to post Share on other sites
TriumphV8 Posted March 31, 2017 Report Share Posted March 31, 2017 I learned that if British engineers use alignment bolts they are necessary. I had endless discussions with people who lost these bolts when repairing customers clutches. I am sure there are many other reasons that the clutch is a bit sticky but why talking and talking when the remedy is that easy and buying and fitting these bolts costs a few cents? When the bolts are fitted one can be sure that one reason to stick is solved and for me thats worth much more than the few pence for the bolts. As these bolts are often gone I make my own on the lathe cutting a M10 down to proper size. It looses a bit from the thread but still can be used.. Quote Link to post Share on other sites
John L Posted March 31, 2017 Report Share Posted March 31, 2017 There is some useful information here, and a drawing of where the dowel bolts should go. http://www.buckeyetriumphs.org/technical/clutch/ReliableClutch/ReliableClutch.htm John Quote Link to post Share on other sites
stuart Posted April 1, 2017 Report Share Posted April 1, 2017 If you need a dowel bolt to make sure this is the problem first of all then take two out of any of the prop flanges to use to get the box aligned for the minute then replace your prop bolts as they have the correct amount of shoulder. I can assure you that the hole at 8 o`clock is the correct size it will just have crud in it. Stuart. Quote Link to post Share on other sites
Andy Moltu Posted April 1, 2017 Report Share Posted April 1, 2017 Or is it a duff release bearing - causing the bearing carrier to get hot and stick on the extension? This phenomenon didn't used to happen until the past few years and has become less common recently. That begs the question as to why? Presumably bell housing to engine plate misalignments have existed since the cars were new (ish) so not convinced by that theory. Slightly worn bearing carriers again is unconvincing - a bit of wear should increase clearance so is this a convincing cause for the carrier sticking? There are bearings that are poor quality, run hot in contact with the clutch and then get hot and transfer the heat to the carrier which expands and takes up the clearance. What soled the problem? A new bronze carrier, special grease or a good new bearing? My money is on the latter but the first two will help as will correctly aligning the gearbox. Quote Link to post Share on other sites
Tom Fremont Posted April 2, 2017 Report Share Posted April 2, 2017 Starter motor bolts will work too. The easiest solution is to slacken every bolt, remove the offending 9/16" bolts occupying the 3/8" holes and fit 3/8" bolts or a pair of 3/8" drill bits. Once you get these in ( you'll have to wrestle the gearbox until they go through ) you can tighten the rest of the bolts, withdraw the bits and put whatever you want in. As Roger indicated, 0.015" is enough to cause trouble; this is roughly half of the clearance provided for the 5/16" bolts, so without dowels of some sort the g'box just drops that amount. Regular 3/8" bolts will work OK but precise ones will give a more, well, precise result. You can also use any intact pair of opposing holes and fit 11/32" bits through them. This is what I did before I learned of the (2) 3/8" holes. Told TRIUMPH WORLD about it and got a free subscription back in the 1900s. Offset gearbox installations have sold innumerable " fixes " for TR clutches; hydraulic throwout mechanisms, belt and suspender throwout fork fastening, etc. This because the t/o bearing always tries to find the centre of rotation ( crankshaft centre ) upon engagement and when this is different than that of the gearbox snout it will drag thereon, guaranteed. Cheers, Tom Quote Link to post Share on other sites
RogerH Posted April 2, 2017 Report Share Posted April 2, 2017 Offset gearbox installations have sold innumerable " fixes " for TR clutches; hydraulic throwout mechanisms, belt and suspender throw out fork fastening, etc. This because the t/o bearing always tries to find the centre of rotation ( crankshaft centre ) upon engagement and when this is different than that of the gearbox snout it will drag thereon, guaranteed. Cheers, Tom Hi Tom, that was also my conclusion. However it is not the dragging whilst engaging the clutch but the carrier digging in on clutch release. Any wear in the carrier ID would make things worse. Regarding the misalignment of my bearing carrier tube to splined input shaft. I set the carrier tube casting up on my lathe and checked it out with a DTI and it was in all effect perfect - everything round, square or in-line. The splined shaft is fixed by the front bearing and its end bearing - these are seriously fixed in place. It should also be square to the front face of the gearbox (where it comes out through the bearing) -but it wasn't To check the eccentricity I turned up a simple ring 1" long x ID=splined shaft OD x OD= OD of steel tube It was perfect at the 9 & 6-o-clock positions but 0.015" out vertically Roger Quote Link to post Share on other sites
oldtuckunder Posted April 2, 2017 Report Share Posted April 2, 2017 Been idling following this thread and wondering why its never reported as a problem on the Vitesse and GT6 given that the engine block is identical, the engine mounting plate is the same(ish) and the clutch cover plate is the same, and whilst the Vitesse and GT6 do have a single locating dowel for the gearbox at about 1min past 12 all it really does is ensure that you have the gearbox and engine rotationally aligned rather than square. About the only major differences are that the Vitesse and GT6 use a brass/bronze bearing carrier and the actuating arm is a floppy arm that pivots on a ball headed pin. Its almost like the TR mechanism is all too fixed so the slightest alignment issue causes problems, whereas the release mechanism on the Vitesse and GT6 I think just adapts to virtually any angle it encounters and pushes squarely on the pressure plate. Never seen any wear on the inside of the bearing carrier either. This was about the only shot I could find of the release mechanism. http://www.rimmerbros.co.uk/Item--i-GRID007802 Alan Quote Link to post Share on other sites
astontr6 Posted April 2, 2017 Report Share Posted April 2, 2017 I rebuilt my clutch assembly last year with the following: AP clutch + Bearing, Revington genuine bronze carrier ( not brass, as some?), Saloon bearing carrier slippers, oil-lite cross shaft bearings, the fork additionally pinned to cross shaft. Result: no sticky clutch or ratcheting!!!!! I fact the clutch has never worked as well even when the car was new? Its just one smooth in and out operation! Tested in M4 traffic jam of 3/4 of an hour! But I also had the gear box/O/D rebuilt which had all new bearings etc. was 43 years old and never been rebuilt. The engine was re-built, I was talked into a fully balanced bottom end and some parts were lightened, some parts were miles out of balance, as shown on their m/c. The end result was an engine that is turbine smooth and ticks over in a different league to what it ever use to? I now wonder if this also has an effect on the clutch operation, especially if the flywheel was out of balance as much as mine? Bruce. Quote Link to post Share on other sites
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