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Mike Muir
Mike Muir
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Help!! I just installed a bob Newby belt drive on my BSA and am having problems. I did all the preliminary work like grind off the aluminum around the front rotor so the belt is clear and the front rotor. Heres my problem. Everything fit fine so I went to install the clutch plates and followed the instructions. 1 green fibre disk first then steel and ended with the orange fibre disk last against the pressure plate. Tightened the clutch adjusters to six turns each and nothing but slip, cant turn the motor over. Tightened the screws till they almost bottomed out, and nothing, a slight more drag but cant even turn the motor over. They sent me 3 steel plates, 1 orange fibre disk and 3 green disks. Im at a loss. Everything is clear and I can turn the motor over by hand with the plugs out. Anyone with a Bob Newby belt drive out there? I did purchase from Diehl BSA triumph. Thanks Tom

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Crikey. The only thing I can think of is.

1) is the clutch hub on the taper and properly torqued down? Some times when you put these things on the key get pushed out of the slot.

2) after you put the pressure plate on did you put the cups in the six holes next and then the springs and then locking nutz last.

3) loosen the lock nut on the center adjustment and take an allen and pull it out. Maybe the clutch adjustment is wrong and is holding the plates open (pressure plate out).

I'm sure you have but get the instructions out and check your work carefully. No parts left on the bench. What year A65 motor?

Any chance of a picture?

Last edited by Semper Gumby; 05/23/21 8:45 pm.
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I did all according to hoyle I thought. The clutch was on the key way, I can kick it through and watch the center section spin freely like your holding the clutch in to check the pressure plate for wobble. Yes, I took the center adj bolt out of the pressure plate just to see. It acts like your holding the clutch lever in while you kick it through. Im really baffled, this is a running bike with no issues, until now.

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I have it off the bike again. I assembled it on the bench and now can tighten the clutch bolts up so the center is tight and I cant move it. I did not originally put the each piece in seperatly, I just fitted them together with the pressure plate. Ill try this method tommrow and see what happens.

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Just tried it again. reinstalled and it was better but its not right by a long shot. Had to tighten the clutch nuts to the point of having like 3 tp 4 threads coming out of the sdjuster. It would finally turn the engine over but barley with slippage too. Also it looks like it needs a spacer behind the front sprocket to space it out a smidge as the belt is not centered on the clutch, its off to the rear a bit.

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Going to have to call diehls up and see if I have some incorrect parts.

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Frank is pretty good about this. I've got one in my race bike A65 from him and it is the best clutch I've ever had.

4) Maybe not enough plates?

Keep digging. The problem will turn up.

What year motor A65?

Last edited by Semper Gumby; 05/24/21 3:13 am.
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Where did you get the 6 turns in from? I haven’t seen this anywhere.

I have the 5 plate clutch so it probably takes up a tad more space in the basket. The nuts are screwed in until they are flush with the studs and then tweaked for level lift. My mate has the four plate the same as you and I think he needed to screw the nuts down further so some thread was showing.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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Nope, apparently some of the Triumphs and BSA's made from 1971 and up have a main shaft in the trans that is extended just a bit more than the earlier ones. So what happens is the threaded end of the shaft is contacting the pressure plate just enough that it would hamper the plate from sitting flush. So the remedy is to take about two threads off the end of the mainshaft and all is well. I figured I took off about 030 thousand and then reassembled. Works like a champ. This was made known to Frank Diehl within the last few monts as he had some emails with someone having the ame problem as I. He talked to Bob Newby and this fix was described to him by Newby. Problem solved. to whoever was asking about the six turns in on the clutch nuts, this were in the short instructions mailed in from Diehs with the clutch. Thanks Tom

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Having bought my clutches direct from Bob, he doesn’t give those instructions with his clutch’s so this is a “frank deihls addition to that clutch”

My mate is running a late 71 and had no issues with the 4 plate clutch (mines the 5 plate so the stack is a little thicker)

Not quite sure what bit your saying nope about though?


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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I've had this problem myself. Make sure the last plate you put in before the thrust plate is steel, and NOT a fibre one. I think you have been sent one steel plate short. Running the red fibre plate against the thrust plate will result in large amounts of red fibre mush inside your primary, and rapid wear. It may work in Japanese trial bikes but not in these old irons.


Gavin
You can't make a silk purse from a sow's ear.
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Originally Posted by wbabojo
I've had this problem myself. Make sure the last plate you put in before the thrust plate is steel, and NOT a fibre one. I think you have been sent one steel plate short. Running the red fibre plate against the thrust plate will result in large amounts of red fibre mush inside your primary, and rapid wear. It may work in Japanese trial bikes but not in these old irons.


I think your unlucky there. I have 2x 5 plate kits like this and haven’t had any deterioration to the red fibre plates.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Joined: Jun 2002
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After phoning Mr Newby and explaining, he sent me another free red plate along with the missing steel, and a locking tool for the Newby clutch. I had been sent one steel plate short. I rode it home to Ipswich from the Isle of Man, at a steady 60, with barely any red material left. Needless to say, it's been perfect for nearly 10 years now, not even requiring adjustment. I've screwed the nuts on the studs till they are flush with the ends.


Gavin
You can't make a silk purse from a sow's ear.

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