Triumph Rat Motorcycle Forums banner

1 - 20 of 34 Posts

·
Registered
Joined
·
551 Posts
Discussion Starter #1
After today’s great ride I parked the bike up (engine hot) and removed the primary inspection cover to see whether the generator stator fitted about a year ago had been rubbing/overheating, that’s what caused the demise of the previous unit. Everything looked good so I thought I’d check the rotor nut while I was there and that’s when I noticed that I could push the crank towards the timing side and pull it back again using pliers on the rotor nut. I could do this easily until the engine cooled down and my rough vernier measurement indicated about 2mm of end float, the manual states that this should be between .008” and .017” or .2mm to .5mm so at best mine is four times the upper tolerance.

If I understand correctly the crank is located in the timing side main bearing, the crank pinion nut clamps it and heat expansion is allowed for the by the crank moving in the primary drive main bearing. Is it possible that the crank pinion nut is loose or am I into a full strip and investigation? I haven’t removed the timing cover yet.

The excessive end float has allowed the timing pointer in the primary cover to contact the two raised sections of the generator rotor scoring a mark on each. The odd thing is that in the attached photo of the old stator (which was taken 3500 miles ago) the marks on the rotor are present indicating that the bike has been running like this at least during my ownership, probably earlier.

I’ve got a feeling I will be reaching for the wallet, what do you think?

720292
 

·
Registered
Joined
·
576 Posts
Hi Chris,

When I rebuilt mine last year (and I think I mentioned it in my T100R rebuild thread) there was about 40 thou of end float on the crank once I'd put the cases back together. Scary. The crank is pulled up to the TS side crankcase when the pinion nut is tightened - there's a clamping washer between the nut and the bearing outer (inner?) which pulls the bearing into the case and takes out almost all the endfloat.

The photos show the ball bearing in the TS, the TS journal on the crank and the TS bearing inner journal - all before I rebuilt it. Can't find a pic of the clamping washer but it has a chamfer on one side.

The DS bearing is a roller and the crank moves laterally on the rollers. I'd have a look in the timing side first, maybe the pinion nut has become loose. There's torque figure (IIRC) for that nut but I found 40 lb/ft was tight. On the 750 I put it back with a drop of Loctite. If you feel the need to take the crank pinion off for a look at the clamping washer and bearing, you need a special tool. At £50..... I let the restorers do that on the 750 rebuild. I thought I'll only ever need that tool once or twice so I have better uses for that money.

Timing cover and check that nut first for my money. IIRC 15/16 or 1", maybe 1-1/8".

PICT0047.JPG



PICT0040.JPG PICT0043.JPG PICT0035.JPG
 

·
Registered
Joined
·
1,386 Posts
Hi Rusty,
Do you know if you have the ball race timing side main bearing, or, the plain bush timing side main bearing.

I would have that timing cover off as soon as possible, in either case the crankshaft is located from the timing side.

good luck.
regards
Peg
 

·
Super Moderator
Joined
·
12,814 Posts
After today’s great ride I parked the bike up (engine hot) and removed the primary inspection cover to see whether the generator stator fitted about a year ago had been rubbing/overheating, that’s what caused the demise of the previous unit. Everything looked good so I thought I’d check the rotor nut while I was there and that’s when I noticed that I could push the crank towards the timing side and pull it back again using pliers on the rotor nut. I could do this easily until the engine cooled down and my rough vernier measurement indicated about 2mm of end float, the manual states that this should be between .008” and .017” or .2mm to .5mm so at best mine is four times the upper tolerance.
I re-named the thread as I'd like to see this discussion go full circle.

IF you end up needing to do a rebuild, go ahead and start a new thread in the Member's Rebuilds section. I hope not, but if you do, those tend to be my favorite threads...
 

·
Registered
Joined
·
551 Posts
Discussion Starter #6 (Edited)
IF you end up needing to do a rebuild, go ahead and start a new thread in the Member's Rebuilds section. I hope not, but if you do, those tend to be my favorite threads...
Me too, I hope my circle is small. If I end up there it'll be a case of deciding whether to have somebody else do it, do it myself with very limited workshop facilities, sell it broken or part it out. First job is to buy the bolt to remove the Boyer rotor.
 

·
Registered
Joined
·
576 Posts
Hi Chris, If you need to strip the motor, it's really not very difficult. And loads of support on here.

The Boyer magnet plate is easy to get off. It's a 5/16 UNF thread inside the rotor hub. Screw in a long bolt until it pushes the rotor off the end of the camshaft. However, provided you get the bolt in a fair way, a gentle sideways tap on the head of the bolt should break the taper (I'll get flamed for that!) unless the PO was ham-fisted. If you mark the position of the rotor and the stator plate before you take them to bits you'll stand a chance of getting them back in the right place easily - but (even though I made a meal of re-setting the 750's timing last week) it's a simple job. You only really need the flywheel locating tool to hold the crank at 38 deg BTDC, and then simply line up one of the magnets with the CW hole in the stator plate, and the engine should run.

If you are taking the timing cover off, it could be a good idea to get new seals for the crankshaft and the magnet rotor (they are the same seal IIRC) and get the seal replacement tool for the rotor seal. Not essential, but it gives you peace of mind. Seals and tools maybe £25 and readily available. The flywheel locating tool is magic - makes timing a doddle.

Don't be afraid of the motor - it's not complicated.
 

·
Moderator
Joined
·
7,412 Posts
Hi Chris,

thread in the Member's Rebuilds section.
If I end up there it'll be a case of deciding whether to have somebody else do it,
sell it broken or part it out.
I sincerely hope you won't do either of the latter.

For worst-case rebuild cost but not too far from you, my first-hand recommendation would be Richard Darby at 3D Motorcycles in Wolverhampton. I've known Richard since the early days of the TR3OC over forty years ago, he's a talented Triumph rebuilder and he has a T100C he rebuilt only a year or two ago. Richard has a Facebook page for 3D.

Also, @DAVE M recommended me to Rockerbox in Wrecclesham, just outside Farnham (Surrey) but I haven't had a chance to try 'em out.

bolt to remove the Boyer rotor.
5/16 UNF thread inside the rotor hub. Screw in a long bolt
gentle sideways tap on the head of the bolt should break the taper
(y)

until it pushes the rotor off the end of the camshaft.
(n)

Hth.

Regards
 

·
Registered
Joined
·
551 Posts
Discussion Starter #10
The timing cover is off and I was hoping to find a loose crank pinion nut but that wasn't the case, I tried to tighten the nut but couldn't shift it, I don't think that's causing the excessive end float (white dots in pics are fine drizzle). The gears are meshing properly with no obvious abnormal wear, everything looked to be as it should to my eyes but the crank pinion must be floating in the same way the generator rotor does when the engine's hot. I think I now need to get the pinion off to check the thickness of the clamping washer behind it, I'm not very confident about doing this without messing up the valve timing and I can't see how a puller would get behind the pinion anyway. I've been in touch with Richard Darby, a nice chap who seems to know his stuff, he can't take the engine until later in the year but it's becoming an increasingly attractive option.

720442
720443
 

·
Registered
Joined
·
576 Posts
Hi Chris,

The crank pinion needs a proper Triumph puller (unless someone knows a work-around) - it screws onto those threads just behind the nut. I have heard of people splitting the cases, undoing the nut and then hitting the end of the crank to drift the crank out of the pinion. My pinion was not very tight so that could have worked, but given that you need the timing cover oil seal to grip that camshaft end spigot in order to pump oil into the big ends, I'd be very wary about that.

The camshaft timing is simple enough to do, but it's a bit of a faff. AIUI, because of the pinion geometry, you may need to turn the engine over up to 94 times before the marks line up. The double dots on the idler match with a dot on the crank pinion, which on mine was hidden behind the nut, so you have to take the nut off to see the mark. My camshaft pinions had 2 marks on each, a dot and a line. I can't remember which is which, but one is for earlier engines and if you use the wrong marks then the valves touch the pistons. My restorer put the pinions on for me and got the wrong marks so I bought the pinion extractor and timed it to the correct marks. If you turn the engine over by hand with the tappets released (and hence the pushrods) and the plugs out this is dead easy to do.

IMHO, it's easier to release the tappets so you can remove the idler and spin the camshafts by hand to get all the marks to line up, then reset the tappets.

Have you still got the 2mm end float at the crank pinion end? Maybe someone knows better than me (decidedly likely) but I can't see how the crank can float unless the clamping washer has worn thin, or something's up with the TS main bearing - which is a caged ball bearing.

Thinking about it, you could undo the crank nut to expose the timing dot, rotate the engine until the crank pinion and idler dots line up and be sure you don't pull the idler pinion out of mesh with the cam pinions (don't need to worry then about the camshaft pinion timing as long as you don't turn the engine over). My nut came off easily with the correct socket and a 2ft breaker bar, IIRC it's a normal thread. You might need a bit of heat if it's been Loctited. A hot air gun on high heat should do it.

Then, with the specific puller, remove the crank pinion and the chamfer washer and you may then get a clue as to what's gone wrong. If it's only the washer then you can easily get another and get back on the road in short order. Shame to wait several months for a slot to get it repaired. Regrettably I don't have that puller otherwise you could have borrowed it.

This is not a difficult job so don't be scared of it!
 

·
Registered
Joined
·
551 Posts
Discussion Starter #12
Have you still got the 2mm end float at the crank pinion end? Maybe someone knows better than me (decidedly likely) but I can't see how the crank can float unless the clamping washer has worn thin, or something's up with the TS main bearing - which is a caged ball bearing.
Thanks Andy. I can't tell whether the end float is still there, it's only apparent when the engine is hot. When I measured it just after a ride I could only move the crank for five minutes or so before the engine cooled sufficiently for the tolerances to tighten up again, when cold I cant move it by hand.

I get what you're saying, none of it is complex if you have access to decent workshop facilities and the special tools. I've got enough to maintain the bike but not for major surgery.
 

·
Moderator
Joined
·
7,412 Posts
Hi Chris,

Were you to dismantle your T100's bottom end, bear in mind you do not need to remove the pinions from the camshafts, it was a particular C-range feature that cams could be removed/changed without splitting the cases. (y)

However, unknown previous rebuilder, engine going back together, it'd be wise to check the timing of the actual cams themselves? The pinion keyways weren't exactly 120 degrees apart precisely so the best match could be found between actual and desirable cam timing.

Hth.

Regards,
 

·
Registered
Joined
·
576 Posts
Others will know better than me I suspect, but if it's only moving when hot, provided the various crank components are still fixed to each other, it can only be the crank moving at the TS, where it should be fixed relative to the crankcase.

The TS end of the crank fits into the inner race of the TS main bearing, so maybe the whole main bearing is loose in the case and sliding sideways when hot, and on cooling it all nips up. If the clamping washer is fine, and the nut is tight and is nipping the pinion onto the inner bearing race, then the main bearing must be moving in the case.

Alternatively, if the clamping washer is somehow worn and hence loose, then it would allow the pinion to move laterally as the crank moves. If that were the case, and you could tighten the nut a bit more, then that would move the crank pinion in a bit, and then it would not line up with the idler as per your photo - the outer faces would not be co-planar. Given that your photos show that the outer faces of the idler and crank pinion are co-planar, I wonder if it's the main bearing moving in the case? That bearing is fitted into a hot case (and the bearing in the freezer) so it does go in easily when the temperature differentials are sufficient - which makes me wonder even more if the problems with the case and main bearing. Maybe then the bearing outer race is moving in the case when hot, and that's not good. But fixable.

If you have a hot air gun maybe you can heat up the TS bearing area to see if you can get the crank to move sideways? If so you'd see the crank pinion move.

That area is fairly simply built, so not much to go wrong and hopefully you can work it out. I think that if you can get the nut off, and the pinion, you'll be able to work out where that end float is coming from.

Here's hoping!

If the worst comes to the worst and you decide not to have a go yourself, there will be other workshops who would get to it sooner than you've indicated. It would be a bit of a trek for you, but the guys I used in Wrexham were brilliant, and they have access to a machine shop if that were necessary. They only work on classics and have plenty of experience and I thought their costs were reasonable.
 

·
Registered
Joined
·
551 Posts
Discussion Starter #15
Decision made for better or for worse. Given that the engine has clearly been running like this for some time (and running well) I’m going to replace the two oil seals in the timing cover, put it all back together and use the bike. I’ll book it in for a full strip and rebuild during the Autumn and accept the consequences if anything bad happens between now and then.
 

·
Registered
Joined
·
576 Posts
Hi Chris, that seems reasonable, and what I'd do, having had mine to bits and now understand how it all goes together. On the TS, the end float only offsets the crank pinion in relation to the idler and a couple of mm should not do any damage for the limited miles in the season.

The conrods have a bit of lateral float on the big end journals, so they should be OK. The rotor moving towards the cover may be an issue, and the primary will change alignment a bit, but I'd have thought if you have a look at the rotor occasionally, and keep an eye out for shiny bits in both main and primary oils, then with an ear out for odd noises, I'd ride it for now. If it develops some odd noises, then stop! I bet there have been 500's ridden for many thousands of miles with worse problems over the years.
 

·
Registered
Joined
·
551 Posts
Discussion Starter #18 (Edited)
Well my attempt to re-assemble didn't go very well. The exhaust cam pinion seal went in ok but the crankshaft seal kept catching on the lower edge of the circlip groove and shredding the outer rubber. After a few attempts the outside diameter of the seal was too damaged to use given its importance so I'm back to square one. The seals came from TMS (UK Made) and looked just like 'normal' black rubber oil seals to me. I have read that the crank seal should be like the one in the link, would this be likely to fit better even if I could source one in the UK?
Edit: The seal that came out was the same as the one in the link.
 

·
Registered
Joined
·
576 Posts
Ah, yes. These are a can of worms - forgot to mention it. Apologies.

I found the seals from one supplier were a very tight fit, whilst those from another were perfect. I bugg*red up a seal that was too tight and tried a different supplier.

Even more apologies, I can't remember where I got the second set from - or the ones I put in the 750, which were also fine.

Stuart (OTP) has a valuable point to make in this thread:


Pioneer Weston only. Those are what I bought for the 750 and they fitted perfectly. This is definitely a case of paying the correct market rate for the best quality seal. You really don't want to be thinking about that seal 50 miles from home, in the rain, when it's getting dark, and you promised to be home in an hour's time.
 
1 - 20 of 34 Posts
Top