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Clutch Fork Tapered Pin - Safety Wire?

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AllanJ71MGB Avatar
AllanJ71MGB Allan Johnson
Princeton, NJ, USA   USA
1971 MG MGB "Batmobile"
1971 Triumph TR6
Thanks Randall. Definitely not running a convertible at -30..... or even -20.

I'll let you all know how I make out. Going to order the parts tonight.

Thanks!

-Allan

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Brett E Brett Evans
Columbus, Ohio, USA   USA
1973 Triumph TR6 "Scarlet Harlot"
If you do remove the gearbox it would be a good time to change the propshaft u-joints as removal of the shaft is so much easier with it out.

AllanJ71MGB Avatar
AllanJ71MGB Allan Johnson
Princeton, NJ, USA   USA
1971 MG MGB "Batmobile"
1971 Triumph TR6
Good idea Brett. Thanks! Question for all of you. Moss has an aftermarket as well as Hardy-Spicer/GKM. Anyone have any experience / preference?

Thanks,

-Allan

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stage3 Avatar
stage3 Christian P
Saarbr├╝cken, Saarland, Germany   DEU
Hi Allan

I have used Hardy-Spicer/GKN UJs in several vehicles and never made a bad experience with them. Certainly better than the unbranded ones some companies sell.

Christian

Brett E Brett Evans
Columbus, Ohio, USA   USA
1973 Triumph TR6 "Scarlet Harlot"
TRF has a kit that includes both u-joits (Hardy-Spicer / GKN) and all new hardware to refit the shaft.

AllanJ71MGB Avatar
AllanJ71MGB Allan Johnson
Princeton, NJ, USA   USA
1971 MG MGB "Batmobile"
1971 Triumph TR6
Thanks Brett. Wish I had seen this a little sooner. I ordered the parts from Moss yesterday and they were more pricey. I ordered pretty much everything I need except the tranny tunnel. The budget for the car is about exhausted.....

AllanJ71MGB Avatar
AllanJ71MGB Allan Johnson
Princeton, NJ, USA   USA
1971 MG MGB "Batmobile"
1971 Triumph TR6
Hi Everyone,

I am reaching out again... I just want to make sure I have my diagnosis right before I pull the transmission out. I have been driving the car a good bit the last week. I took it for a 60 mile drive to and from my folks place last night.

At times the car would go into first with no issue at full stop. Most other times it was a total bear to get into first and in some cases I had to time the traffic lights to turn the car off, drop it into 1st clutch in, and restart the to get going in first. Others times I could get it into second and roll the car enough forward to get it into 1st. Reverse grinds slightly so I have been turning the car off and dropping into reverse and restarting.

The car shifts fine when moving. No grinding. It is a wonderful ride 2-4 +OD.

Is this all symptomatic of the clutch fork pin? It just seems so erratic. Is there anything else I should look at?

Also, my speedo died again (It was broken when I got the car). I had a brand new angle drive and cable. The odometer did not work but the speedo part did and then it failed yesterday about a mile into the trip (been working all week). I used the washer in the angle drive like I was supposed to. Could it be the speedometer causing the failure? Is 3000RPM @60mph in 4th+OD normal? Seems high to me. My MGB is lower if I remember correctly in 4th+OD (Haven't driven it in a bit).

And my tachometer is REALLY noisy in a cyclical way. Anyone have any experience with that?

Thanks!

-Allan

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
Your clutch problems could certainly be something other than taper pin. The original setup is fairly marginal anyway, so anything that reduces travel at the TOB can cause problems.

One of the first things to check is the thrust washers in the engine. For reasons I've never understood, the TR6 only uses a half washer, and it is prone to rapid wear. Any wear can allow the crankshaft to float back and forth, which can push the clutch slave piston back into the cylinder and cause low travel next time. It's wise to check the wear periodically, since if it gets bad enough, the washer can fall out into the crankcase and allow the crankshaft to contact the block (next time you use the clutch), causing substantial damage to both.

Another common problem is wear at the pivot between the clutch pedal and the MC pushrod. That joint needs a drop of oil once in awhile, but frequently gets overlooked. The pin is easy to replace, but the holes wear too. On the Stag, I was able to make a temporary repair by reaming the holes slightly oversize (more nearly round) and using a hardened metric bolt for the pin. But of course the right solution is to remove the parts and have them welded, so the holes can be reamed back to original size.

Less common problems include weakening of the plastic line from the clutch MC to slave (improved "SS braid" lines are available from several sources, including TSi http://www.tsimportedautomotive.com/tr250_tr6.html )
There should be springs inside both the MC and slave. MC springs sometimes break; the slave spring is sometimes missing entirely.
Make sure the clutch pedal returns all the way. It should pull (lightly) against the MC pushrod.

Some people have even gone as far as to fit the clutch MC from a 69 TR6, which has a slightly larger bore. The larger bore means a bit more force at the clutch pedal; but also increases the travel at the slave. Sometimes it's enough to overcome the other problems.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
Could well be the speedo causing the angle drive to fail. There is a bushing in there that dries out over the decades. If it turns a bit stiff cold, then the bushing material gets hot and binds worse after driving a few miles.

3000 rpm @ 60 mph sounds like your OD is not working. What do you get with the OD disengaged?
Obviously, could be either tach reading high, or speedo reading low.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

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AllanJ71MGB Avatar
AllanJ71MGB Allan Johnson
Princeton, NJ, USA   USA
1971 MG MGB "Batmobile"
1971 Triumph TR6
Thanks for the reply Randall,

I guess I am a little confused about how all this works..... hoping you can explain.....how does the TOB affect the ability of the transmission to drop into gear? If it is not pressing fully, my brain is suggesting the gears just grind if I am at stop and go from Neutral to 1st? Again, I can force it into second (and I mean FORCE) with no grinding, get it rolling and then FORCE it into 1st. Whereas without it rolling, full clutch, I cannot physically force it into first but it doesn't grind either. The only grinding is reverse. I am assuming it is because it is non-synchromesh.

Also, could I be burning through my synchros driving this car? (drove it today to work - gorgeous out). Is the lack of full clutch being compensated by the synchros?

How would I check the thrust washers in the engine? I am planning on just pulling the transmission (I don't have a hoist). Can I just see if there is any horizontal float in the crank by pulling and pushing on the flywheel when the transmission is out? Or am I not going to be able to manage that? (with any degree of detection?) Or is this check something that needs to have the engine pulled? Or just the oil pan?

I've got all new clutch hydraulics. They seem to be working correctly with adequate travel and the pedal returns to its starting point. I guess it is possible I need to bleed it more but it is fine in gears 2-4 (not reverse).

The OD was definitely working with it off it was around 3600 for 60 mph. It seems really fast by the engine pitch.... My MGB without OD was 3K and with is around 2400 @60mph. The TR6 speedo had just broken so I installed a GPS speedometer on my smartphone called DigiHUD (Android). Kind off cool. It also has a HUD mode which works like an aircraft HUD where you can lay it on your dash and it mirrors the display so that when it reflects off the windscreen and you can see your speed correctly reflected in the windscreen. I've used it in my Toyota Camry and it's speedometer seemed pretty on target with the App. Also, it seemed pretty accurate with the traffic speed on the interstate: At 60mph, I was falling behind and at 70mph I was keeping pace with traffic.

Did the TR6 have a different gearbox ratio set available or a different rear differential that could be changing the final drive ratio and making it high? I looked online but didn't find anything.

I've never really dealt with a slipping clutch.... while it could be slipping during acceleration it seems proportional in all gears and 'launch' seems normal to me. I tend to think your suggestion of the tachometer being off is an option. I know the tires are correct. I think I am going to rig up a tach/dwell meter I have while driving so that I can see if it is off. I am not sure how off it could be though.... the engine sounds really fast at idle and the tach is reading about 2K.

Thanks,

Allan

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
In reply to # 1465470 by AllanJ71MGB Thanks for the reply Randall,

I guess I am a little confused about how all this works..... hoping you can explain.....how does the TOB affect the ability of the transmission to drop into gear? If it is not pressing fully, my brain is suggesting the gears just grind if I am at stop and go from Neutral to 1st? Again, I can force it into second (and I mean FORCE) with no grinding, get it rolling and then FORCE it into 1st. Whereas without it rolling, full clutch, I cannot physically force it into first but it doesn't grind either. The only grinding is reverse. I am assuming it is because it is non-synchromesh.
Perhaps I have assumed too much, Allen. To shift to reverse, you should first depress the clutch, then partially select one of the forward gears, then shift into reverse. That uses the synchromesh of the forward gear to stop the gearbox input shaft from spinning, so you can engage reverse without grinding. If it still grinds, even a little, that is a fairly certain sign that the engine is still trying to turn the input shaft. Usually, it means the clutch is not fully disengaged (but could be other things).

Quote: Also, could I be burning through my synchros driving this car? (drove it today to work - gorgeous out). Is the lack of full clutch being compensated by the synchros?
Yes, that is exactly what I think is happening and it will wear the synchros out eventually. Then you'll start getting grinding always, instead of just in reverse. A healthy synchro ring will keep it from grinding, at the expense of not letting the gear teeth touch until they are synchronized. (They are also sometimes known as 'baulk' or 'blocker' rings for just that reason.)

Quote: How would I check the thrust washers in the engine? I am planning on just pulling the transmission (I don't have a hoist). Can I just see if there is any horizontal float in the crank by pulling and pushing on the flywheel when the transmission is out? Or am I not going to be able to manage that? (with any degree of detection?) Or is this check something that needs to have the engine pulled? Or just the oil pan?
IMO it is best to have a dial indicator and magnetic mount. They aren't terribly expensive (under $30 for a cheap import last time I looked). There is a very small range allowed; something like .005" minimum and .007" maximum (please check the book, I may not have the numbers right). A little bit more probably won't hurt anything, but even .010" is really tough to judge by eye.

With the engine off; step on the clutch to move the crankshaft all the way forward. Setup the dial indicator so it is bearing on the end of the crankshaft, axis in line with the crankshaft and note the reading. Then lever the pulley (and crankshaft) to the rear. The change in reading is the end float. IIRC there is a diagram in the workshop manual. Although they show the engine out of the car for clarity, it can be done in the car.
Quote: Did the TR6 have a different gearbox ratio set available or a different rear differential that could be changing the final drive ratio and making it high? I looked online but didn't find anything.
Yes, definitely. I don't think the factory listed them as an option for the TR6, but the optional 4.1 gears from a TR3-4 will fit the TR6 diff; as will the 4.30 gears from some other Triumphs. They are often used by racers, in combination with other modifications causing the engine to reach peak power at higher rpm. There is even a 4.56 set that will fit (but I can't imagine where it would be useful).

For example, my current TR3 came to me with a 4.1 axle. Since it didn't have factory overdrive, and it didn't have the right speedo head for a 4.1 axle; I'm pretty sure a previous owner changed it.

Quote:
I've never really dealt with a slipping clutch.... while it could be slipping during acceleration it seems proportional in all gears and 'launch' seems normal to me. I tend to think your suggestion of the tachometer being off is an option. I know the tires are correct. I think I am going to rig up a tach/dwell meter I have while driving so that I can see if it is off. I am not sure how off it could be though.... the engine sounds really fast at idle and the tach is reading about 2K.
Again, strange things can happen. The tach is the same movement as the speedo (without the mechanisms for trip and odometer). I put a used speedo from another TR3 onto mine, and it would bounce between 90 and 120 mph while I was actually only doing about 75.

FWIW, here's a video I just found on YouTube, showing how the synchro/blocker rings work. The other details aren't exactly identical to the TR gearbox, but are very close. It's that last step, where the ring has to turn back a bit to allow the shift ring to slide over it, that makes it hard to shift if the clutch (or pilot bearing) is dragging.




Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

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