Restoring & Modifying 1971 OIF TR120

[atomsplitter]

Enjoy reading your journey of rehabing an old scoot. Am interested in how it performs once completed.

 

[Rocky]

Enjoy reading your journey of rehabing an old scoot. Am interested in how it performs once completed.

Me too. Great to follow this and looking forward to the finished product

 

[NM Bonny]

The clutch basket appears new, as do the clutch plates and primary chain. However, isn't there supposed to be a tab washer (2nd pic) that bends up to retain the central clutch hub nut...? If so, whoever renewed the clutch and primary left it out...

Question: which way are the threads on the alternator rotor, R/H or L/H? I think the clutch hub nut is regular R/H threads, but the rotor...?

 

[NM Bonny]

Never mind: I believe that the threads on both nuts are ordinary R/H versions...

Weirdly, whoever replaced the primary chain, clutch basket, and plates appears to have left out the tensioner (see pic). Judging from the photo at one of the parts houses (2nd pic), those are wear grooves in the surface--so it's just about worn down to the metal spring plate...

Ah, well. I'll go ahead and install the 20T tranny sprocket and new seals. When the rotor and tensioner get here in a few days, I'll be ready to button up the primary and move on to the last few steps to get her ready for the first test ride!

 

[grandpaul]

Here's where I am thus far:
... And away we go...

This has become THE most popular thread on this forum!

 

[NM Bonny]

This has become THE most popular thread on this forum!

Well, now I'm going to have to shave and shower every morning...

Seriously, though, I'm glad it's useful or entertaining or both.

 

[Rocky]

Well, now I'm going to have to shave and shower every morning...

Seriously, though, I'm glad it's useful or entertaining or both.

Oh yeah, we're loving it

 

[NM Bonny]

Glad to hear that.

So, I got the primary chain, sprocket, and basket off... indeed, they look great and are going back in as is. There was very little residue in the bottom of the primary case, so I got to use my old steering wheel puller to yank the 19T sprocket, which is shown compared to the new 20T version.

That oil seal puller I had purchased in the '80s to R&R the front crank/timing cover seal on my '63 Cadillac Coupe de Ville... worked great here. The output shaft bearings felt fine.

As you can see, the 20T sprocket just slips into the hole. I applied some non-hardening silicon to the flutes to help it seal against seepage along the shaft--a trick people do on the old 4-speed Harleys like my '51 FL.

Also installed the Renolds (final drive) chain, so mañana I'll tighten the sprocket nut and bend up the tab washer. Should have the new rotor and trap door oil seal Friday, so hope to have the clutch pressure plate aligned and the primary buttoned up this weekend!

 

[NM Bonny]

Looks like I left off the image showing how close the fit is with the 20T sprocket. It just grazes the case going in, but does fit, as you can see...

I couldn't resist going with allen screws and acorn nuts for the conical hub after all that sanding and polishing work. The nuts have loctite on them in lieu of nylock inserts.

Hmmm... looks like the mushroomed ends on a couple of the spokes on the rear hub didn't settle into their countersinks all the way. I'll have to tap them with a drift and retighten those spokes...

Finally, in response to a PM: no, I am not omitting the front fender. It was absent in the last several photos of the bike because I had miscalculated the shims needed for the DIY front 'big brake' disc conversion. So, I corrected that and installed the front fender today.

The finished thickness are: R/H side - . I06"; L/H side - .1575~.159". Those could well be one-piece turned spacers in a kit if I were to offer one, but I used separate shims from McMaster Carr I had lying around: R/H - 1x .09" and 1x .016"; L/H - 1x .125" and 2x .016" and 2x .001".

Question: the 'general data' says 25 ft. lbs. for the front spindle (axle) cap retaining nuts. Really?!

I think the similar nuts on the R/H side of my Harley's fork are 15 ft. lbs, and I'm a little concerned that 25 ft. lbs. will crack the aluminum caps.

Any applied experience to correct me or set my mind at ease, here?

 

[Rudie]

the 'general data' says 25 ft. lbs. for the front spindle (axle) cap retaining nuts. Really?

No! Never.

It's a misprint, hangover from the pre 71 steel sliders and axle caps.

In something like 79, Meriden finally changed the torque figure to 15 ft lbs on the similar disc brake alloy sliders and axle caps but imho that is still much too high.

Because of the failure of NVT within a year of launching the T160, the official workshop manual (still with the misprint ) did not appear until the early 1980's. By then, I had had my T160 for several years; first time I had to tighten the axle cap nuts, I looked at the enormous gap between slider and cap, did the nuts up equally either side of the axle with an ordinary wrench 'til they were "tight". Always done all those cap nuts that way ever since, never cracked a single cap (my T160 still has its now 49 year old originals ... ).

 

[NM Bonny]

No! Never.

It's a misprint, hangover from the pre 71 steel sliders and axle caps.

In something like 79, Meriden finally changed the torque figure to 15 ft lbs on the similar disc brake alloy sliders and axle caps but imho that is still much too high.

Because of the failure of NVT within a year of launching the T160, the official workshop manual (still with the misprint ) did not appear until the early 1980's. By then, I had had my T160 for several years; first time I had to tighten the axle cap nuts, I looked at the enormous gap between slider and cap, did the nuts up equally either side of the axle with an ordinary wrench 'til they were "tight". Always done all those cap nuts that way ever since, never cracked a single cap (my T160 still has its now 49 year old originals ... ).

Thank you for weighing in, Rudie. Thank goodness I didn't follow the OEM manual! BTW, I'll bet that's why one of the caps which came with the original '71 sliders was cracked.

Okay, I'll do the same, and intend to include a 7/16" wrench in the under-seat tool kit I'm assembling. I'll likely make it a habit to give them a nip whenever I fill the tank. Only takes 30 seconds, and it'll give me peace of mind zipping through the canyon on my way up from the river...

Since we're on the subject, are there any other torque specs which are suspect?

On an unrelated note, I watched "Coogan's Bluff" while cooking a pot of red curry this afternoon, and had forgotten about that wonderful chase scene on what looked like a pair of '68 Bonnevilles.

 

[NM Bonny]

Enjoy reading your journey of rehabing an old scoot. Am interested in how it performs once completed.

I'm really curious, too. It's been a long time since I rode the presumably analogous '71 Yamaha XS1B 650 that I owned in the early '80s. But I recall that it was a blast to ride--save for the ventilated DLS front drum brake, as discussed earlier in this thread...

I have an extended battery pack that plugs into my GoPro. So, once I've got the carbs dialed in for 5,000~6,000 ft. (my usual operating range--from the river up to the foothills of the Sandias where I live), I will definitely share some POV clips to give you a sense of how she does.

I'm particularly interested to see how the DIY 'big brake' front disc conversion works. It was a vast improvement on the '51 FL, but here we're talking about the same size disc (11.5") on a bike that's nearly 150 pounds lighter (a Panhead of that vintage weighs 560 lbs). Should be fun to watch the videos!

 

[Rudie]

intend to include a 7/16" wrench in the under-seat tool kit I'm assembling. I'll likely make it a habit to give them a nip whenever I fill the tank. Only takes 30 seconds, and it'll give me peace of mind

Fwiw, I have never had an axle cap nut come loose; my T160 has both plain washers and oblong section spring washers between each axle cap and its nuts; alternatively, I fit all metal Staytite self locking nuts with just plain washers.

Friend of mine, also a long-time T160 owner but a proper mechanical engineer explained I was likely bending the cap elastically; so bent imparts considerable additional friction between nut and stud threads but a cap returns to its original shape when the nuts are loosened. He surmised particularly original cast caps probably transition quickly from elastic to plastic bending when they crack.

 

[NM Bonny]

Fwiw, I have never had an axle cap nut come loose; my T160 has both plain washers and oblong section spring washers between each axle cap and its nuts; alternatively, I fit all metal Staytite self locking nuts with just plain washers.

Friend of mine, also a long-time T160 owner but a proper mechanical engineer explained I was likely bending the cap elastically; so bent imparts considerable additional friction between nut and stud threads but a cap returns to its original shape when the nuts are loosened. He surmised particularly original cast caps probably transition quickly from elastic to plastic bending when they crack.

Well, thanks for the reassurance. I needed it...

That makes good sense. I currently have standard split lock washers and stainless nuts on the studs but have nylock nuts on the Harley's cap. I may switch to nylock nuts, as I've had good luck with them.

Your friend is right: high-quality aluminum with a temper like T6 flexes, though the deflection is hard to see in most applications (the 6061-T6 clip-on handlebar clamps flexed way more than I thought it would when tightening down--a little disconcerting).

What my machinist would likely recommend had he made the caps would be leaving little stops of [x] height at all four corners of each cap, so that the degree of flex--and resulting friction against the nut and clamping force on the axle--was fixed and consistently achieved. One would then simply torque the fastener to whatever spec is appropriate for its diameter, threads, and material, and not worry about this stuff.

Another issue:

The OEM setup has an axle (if I'm reading the diagram in the manual correctly) that has a collar machined into it near the center...? So, no way the axle could slip sideways out of the caps. However, I am using a simple piece of (very hard) steel as an axle: the only thing preventing its lateral movement is the clamping force from the caps, and of course the weight of the bike.

Therefore, I had mused about having my neighbor/machinist turn grooves for circlips into the ends (there's ample length to do that). But perhaps this is unnecessary fretting.

 

[atomsplitter]

"It's been a long time since I rode the presumably analogous '71 Yamaha XS1B 650 that I owned in the early '80s."

I've owned a number of the old XS 650's, the last two I owned I shipped to Australia to a collector. Here's a pic I took of one of those bikes after getting it cheap as a non runner from a friend. That's a stroll down memory lane........(thank God for Mike's XS.com for parts)

 

[NM Bonny]

"It's been a long time since I rode the presumably analogous '71 Yamaha XS1B 650 that I owned in the early '80s."

I've owned a number of the old XS 650's, the last two I owned I shipped to Australia to a collector. Here's a pic I took of one of those bikes after getting it cheap as a non runner from a friend. That's a stroll down memory lane........(thank God for Mike's XS.com for parts)

Yeah, that one had to be a year or two later than mine, which had a gold-and-white paint job and the ventilated TLS front drum brake. Thanks for this!

 

[Rudie]

The OEM setup has an axle (if I'm reading the diagram in the manual correctly) that has a collar machined into it near the center...? So, no way the axle could slip sideways out of the caps. However, I am using a simple piece of (very hard) steel as an axle: the only thing preventing its lateral movement is the clamping force from the caps, and of course the weight of the bike.

Therefore, I had mused about having my neighbor/machinist turn grooves for circlips into the ends (there's ample length to do that).

Not only do all the different OEM Triumph front axles have the "collar" (that primarily locates the axle relative to the hub through the fixed bearing), almost all also have a semi-circular cutaway around the axle close to each end, the cutaway locates between the bolts or studs (outer studs on your bike's forks) into each slider, these bolts or studs are closer together than the diameter of most of the axle.

 

[NM Bonny]

Got slowed down today because when I tried to use the tranny and rear brake to hold the primary still to tighten the rotor and clutch hub nuts, I noticed movement in the rear-set bracket I'd made. The slop was not only disconcerting; it also likely reduced the efficiency the lever.

So, I drilled another hole (5/16"), made up a plate to go in back, and added another bolt. Very rigid. Now, with tranny in 2nd gear, the brake held the primary firmly enough to tighten the nuts to 30 and 50 ft. lbs respectively.

Ah, well... better to have a design weakness show up on the stand rather than out on the highway! I've included measurements of the second component for anyone who may wish to replicate this DIY rear-set design. (The bolt has to come through from the back to allow clearance for the brake backing-plate stop strut.)

Installed a new tranny sprocket 'trap door' seal and added Ultra Gray non-hardening stuff (Yamaha Bond is similar) to the paper circumference gasket to eliminate drips from the primary case. I used copper washers in place of the OEM fiber ones on the plugs.

Found that the easiest way to press that fiddly trap door will seal into the slim recess was to put it into the bench vise with a piece of wood. Voila.

Finally, had to gently carve out some of the molded plastic around the alternator stator's nuts to get a socket on them. But now I've got a new rotor and 3-phase alternator, which will be nice. Had to enlarge the hole in the no-ooze boot to accommodate the fatter 3-wire lead. (Did I mention that KM Jones is way cheaper on the new Lucas rotor?)

Anyway, the primary is ready for chain tensioning, clutch plates, and (gulp) yet another polished cover... at least this one is the least damaged piece I've laid hands on to date.

Question: the manual says 3/8" freeplay in the primary chain, and shows a a guy pushing down through the hole with his finger.

However, the way the chain lies, it's far easier to judge tension by lifting it, because pushing down produces very little movement even when there's significant slop up and down.

So, what's the best method of measuring freeplay?

 

[Rudie]

had to gently carve out some of the molded plastic around the alternator stator's nuts to get a socket on them.

When the Co-op changed to 3-phase alternator stators, they had to change the mounting nuts and washers - to small hex and small o.d. respectively - because Lucas crammed in nine stator coils in the same space as six in single-phase stators. However, what the Co-op never did was change the nuts and washers part numbers in the parts books ... fwiw, I use 21-2177 nuts and 70-3446 washers.

Question:

What the manual does not show or mention is the child labourer pressing down on the kickstart against compression to get all the chain slack in the top run ... Then I both push the chain down and pull it up to measure the total slack.

 

[NM Bonny]

When the Co-op changed to 3-phase alternator stators, they had to change the mounting nuts and washers - to small hex and small o.d. respectively - because Lucas crammed in nine stator coils in the same space as six in single-phase stators. However, what the Co-op never did was change the nuts and washers part numbers in the parts books ... fwiw, I use 21-2177 nuts and 70-3446 washers.


What the manual does not show or mention is the child labourer pressing down on the kickstart against compression to get all the chain slack in the top run ... Then I both push the chain down and pull it up to measure the total slack.

Ah, I see... you're a wealth of information! So, I guess the only downside would be that the nuts are not locknuts...? Perhaps no biggie, as they're not likely to vibrate off. I'll include those part numbers in my notes for future reference.

Okay, I'll adopt your method for checking tension once the cover's in place. Easy to measure with it off, obviously...

Before I button up the primary, I decided to order new clutch plates to have a set on hand--but also to compare thickness to what I've got. The book doesn't state a wear spec (unless I'm missing it) but simply tells you to compare a new set to the existing one.

I see that I neglected to post the final photo in the rear-set series showing how the retention plate mounts (if it wasn't obvious). I used 3/16" steel to match the pivot plate (so it wouldn't bow when the bolt was tightened), and it just clears the swing arm. It'll get painted whenever I fabricate the aluminum brake shoe backing-plate stop strut.

I realize most chaps would simply weld on the pivot plate. But I have this weird aversion to welding (or cutting) vintage frames, unless for repair. I made up a spring mount for the same reason when fitting a solo saddle to my '51 FL, which has an unmolested frame with sidecar and tool box mounts...