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by Mal Marsden - 06/16/22 7:00 pm
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Allan G, Hillbilly bike, kevin, Lorenzo, Mark Brown, slofut, Stein Roger
Total Likes: 10
Original Post (Thread Starter)
by desco
desco
Most of the the time I cannot get the 72 to go into neutral with the motor running. How ever there have been times where it will. All else is fine. No grinding. Shifts like butter. I no longer have the back or the patience to spend hours making microscopic turns of the adjustment screw to get it right. Is there a correct amount of lift? I have a dial indicator.
Liked Replies
by gavin eisler
gavin eisler
IMO the main source of clutch trouble with the T type 3 spring clutch is a worn shock absorber unit. If this is gubbed, no amount of spring balancing , new plates , finicky adjustment, will make a blind bit of difference. The cush drive was never meant to be rebuildable, having tried I now categorise attempting to repair the shock absorber as a senseless waste of human effort, once worn it allows the clutch basket to tip under load, regardless of how fresh the plates and springs are or how clean the clutch tang grooves are.. The only non wearing part of the cush drive is the outer end plate; the spider , inner end plate, rubbers and notched drum are all wearing items. In the Uk a new clutch centre cush drive unit costs about 100£ , money well spent.
3 members like this
by TR7RVMan
TR7RVMan
Hi, Yes the splines, on the repro are loose. It's the spider splines, not hub. Yes they will wear. This just sucks! Be sure to loctite the clutch nut is all I can say.

Of course you could loctite the splines. That would work. Heaven help you if you needed to take it apart again. I guess you could heat it to 300f with heat gun. Rubbers would be junk anyway. I might do that next time.

I was going to machine spider square again, resurface back plate. Turn the shoulder deeper on outside to compensate. That would work. But.... The back plate is hardened. My lathe wouldn't touch it. Must be surface ground. I don't have surface grinder. I'd already filed grooves & they needed it again.

So I had to buy new one. Could not find genuine Triumph NOS. All the NOS parts were NOS Harris, NOT!!! Triumph. This is huge problem on eBay with NOS. Yes it's NOS, but actually is Harris or Wassell. Same crap as they still sell new, but with light layer of dust & rust. Luckily I'm 70 now so only need to get by another 5-10 years. Maybe less? Who knows? I don't even buy green bananas.
Don
3 members like this
by TR7RVMan
TR7RVMan
Hi desco. Adjusting the rod, first thing is back off bar adjuster all the way. Turn in screw until you see & feel pressure plate lifting. Feel clutch lever. You MUST, MUST, MUST lever play with plate slightly lifted. This is where things go horribly wrong when owners have problems adjusting clutch. Not having free play when adjuster screw is zero clearance & slightly lifting pressure plate. It leads to the dreaded click! That is how they get the click, lack of cable play during rod adjustment.

If you don't have cable play.... on later bikes with threaded lower adjuster on cable, screw the adjuster deeper into trans to get some play. On earlier bikes with no lower threaded adjuster, no play you need shorter cable abutment. Not so simple on the early bikes.

If nothing else temporarily remove clutch lever. This allows the cable to slide into housing deeper. You'll have to back off rod adjuster screw to get slack to remove lever. Once lever is off, start over with rod screw. Lift pressure plate slightly. Now look at cable top end you should & will have play with no lever on cable.

Back to the rod screw. Now I back out screw until it's free. Then screw it in lightly until you feel it contact rod & rod has zero play. The screw will suddenly be hard to turn. If you go deeper it will begin to lift plate. But don't lift plat. We want rod/screw to just zero play with no lifting or starting to lift.

Now back out screw 5/8 turn. Counter hold screw & lock the nut tight. Don't let screw spin tighter when locking nut.

Now adjust cable with bar adjuster. If needed bring the lower threaded cable adjuster up if needed.

Depending on bar adjuster length, lever, perch version, you may run short of bar adjuster & need to readjust the lower end of cable. On early bikes than would mean changing abutment again. That is why removing lever is occasionally the better choice to get cable play during rod adjustment.

To be very clear, the point of lifting pressure plate slightly with rod screw, then verifying you have cable play is to fully seat the ball cam to zero. You must have cable play to achieve the zero point. Otherwise the cam is turned some amount & balls are on ramps, not at zero.

Cable play cold depends on lever/perch combination. I try to leave at least 1/64" cable play cold. More is better like 1/16-1/8". As plates wear the cable play gets less. You MUST have cable play or the rod will have pressure more or less on it. This causes the ends of rod to overheat. Melts ends of rod, the pressure pad in cam, the adjuster screw, & melts/wears mail shaft rod bushing. There is never ever an excuse other than neglect or lack of knowledge for an overheated rod. AT THE SAME TIME!! if you fail to keep eye on rod adjustment the rod can have zero play while the lever has plenty of free play.

So there is 2 things to keep an eye on. The rod & lever play. I've found if you check rod adjustment every 1500 mile oil change that is enough unless you racing or have clutch slippage. The cable adjustment you feel every time you free clutch at cold start.

Keep in mind the lever gets more play hot as things expand. So if you tighten cable hot, where will it be cold? If you need more lift hot which very well could be (you've already set rod perfectly), Then it's time to look at modifying lever or perch to get more cable travel. My bike I needed to do that. Smoking hot in stop/go traffic 110f day my clutch would not release. Cable play had to be taken out in that heat. Then next morning I had tension on cable, not just tiny free play, but cable was actually being pulled.

That's what prompted me to modify the used donor lever. It worked perfectly. I ultimately modified donor perch & reinstalled original level. That is what my bike current is using to very good results.

Takes some time & effort to set the clutch system. But once it's done it's really nice operation. Seems the '70 & older had less problems with release. On paper the alloy perch should pull same amount of cable, but I've found them to not do that sometimes. For whatever reason. So I've gotten to look at every bike in it's own right. I don't jump to conclusions, but start with rod adjustment first, then move on.

Wear in cam on higher milage bikes is common. The ball ramp flattens. The pivot hole can wear so when operating lever is pulled by cable the rotating cam moves sideways a little give lost motion, worn ramps & balls give less lift for a given rotation. Rust & ramp/ball wear is the main problems I've observed.

I know it's cheating by modifying bar lever can overcome cam wear & some other wear problems to a degree until wear is too great. Maybe get another 10-15+k miles on current parts. Wear in fulcrum hole in lever often results in lost motion of cable.

That's my experience. Of course all worn parts should promptly be replaced. Going through full primary overhaul is about $700+. Not chump change for most of us. So you can often make do with very good results with some thoughtful work.
Don
1 member likes this
by TR7RVMan
TR7RVMan
Hi Draco, Factory gave no spec on lift that I’ve been able to find. As you think, lift is very important.

I spent a lot of time measuring lift on different bikes. Some came from factory with only .073-.085”. My ‘73 Tiger was like that. I have found .115-120 to .125” works best. Over .125 it starts doing odd things like can drag more or drag very slightly during shifting.

Lots of factors in how much lift you get. Grip thickness, lever perch type. Wear in lever fulcrum. Ball cam version. Wear in ball cam. Cable brand & how much compression in housing & stretch in cable. How much free play you have in rod adjustment, how much play you have in clutch thrust washer, spider. How much free play you have in cable.

For problem cases I’ve ground face of lever to perch so end of lever is farther from grip. I’ve modified perch in similar fashion to move lever end farther from bar. This allows lever to pull more cable.

Doing experiments I found the cam has lost motion. This is counter intuitive but backing screw out a little further like 5/8 turn compensates somewhat for lost motion. You compensate for the clearance with bar adjuster. So cam is clocked slightly further on ball ramps so they are at steeper part of ramp.

Running less cold motor cable play gives more pull. The play increases as motor is heat soaked. That is normal. But you must really pay attention play does not go to zero & give rod constant contact.

After setting rod to 5/8, the next easiest thing is modifying lever. I started out by experimenting with used levers. You can only grind so much or the lever gets too tin at cable end hole.

Grinding perch is more difficult as the alloy ones will need to be hollowed/relived near fulcrum. I used tiny burr in Dremel tool.

Lift is only one part of clutch drag. Wear in thrust washer & spider sides allows end float & wobble with lever pulled.

Of course wear in grooves of basket & drum & plate tangs makes plates not want to separate.

Often a little wear here, a little there adds up to not perfect freeing.

6 plate clutches with the full width friction pads have more drag than 7 plate with the smaller pads, even though 7 plate gives 2 more friction surfaces.

Oil type can make big difference.

Of course if wobble is way out that’s a problem. So long as lift is in the .120” range it will tolerate minor wobble no problems.

What to do? Measure lift first. You can just use depth gauge on vernier caliper through adjuster hole on primary cover. Pull lever & hold, measure. Release lever measure. Subtract difference = lift.

Often lift is good & clutch has slight drag. But overall works fine. Shifts fine. Often, if you come to standstill in 1st, you can lightly blip throttle. Just at the very cusp of rpm drop the shafts are neither accelerating or decelerating, the gear dogs are unloaded. At that very moment click into neutral. Thales some practice. Let out clutch easy to verify it’s actually in neutral.

Engine idle rpm has direct relationship with gear momentum. Slower the idle the better finding neutral works. But slow idle not good for oiling & promotes stalling.

Modern thin trans oil is slippery & allows gears to rotate freely. So in can take 4-6 seconds for them to coast to a stop even with perfect clutch.

5 speed with the steeply back cut gears hold together tightly with even slightest clutch stage.

The late extra stiff T140 gear shift centering springs help. It just feels better to my toe so I can feel neutral better.

On paper the clutch is very simple. But there’s a lot actually going on with the relationship of so many parts, plus oil differences. In real life not simple at all. But certainly we can overcome all these issues & have a clutch that works as good as it can.

Draco, try the throttle blipping on next road test. You may already be doing the blipping though.
Don
1 member likes this
by Dibnah
Dibnah
In my limited experience with Triumph clutches there appears to be several variables, a combination of which can lead to crunching gearchanges and slipping plates. With my 650, the biggest improvement was running the clutch with no oil and no outer primary chaincase, but not for very far, perhaps 20 miles in total.
1 member likes this
by Hillbilly bike
Hillbilly bike
Now you all know why newer bikes have the Cush drive, if required, in the rear wheel drive…
Other than the usual few jabs to free the clutch, I have never had clutch issues on any bike..Well, I did have trouble with Barnett plates refusing to disengage on the race bike…
As Reverb says, some new bikes have difficulty finding neutral….I just find neutral as the bike comes to a stop..
1 member likes this
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