75 E-Start Sprag clutch

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On this last failure, with all three components brand new, I decided I would definitely not spend another penny on one of these sprags. I called around and found a couple of sources of the old style 14-tooth sprags. And one source, Fair Spares America, said he would not be stocking the 18-tooth versions any longer, because of problems.

I haven't ordered a new 14-tooth sprag (still getting over the amount of money I have spent on this problem already), but I that's my plan. Can't be worse than what I've been through already.
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I don't think the 14 element vs. 18 element is the answer. I have locked up both over the years. If the spring isn't broken, you can carefully realign and re-use them. If you are continually breaking or locking them, then I would back off your anti-backfire device. I am using mine on a big valve, high compression motor, so I have to set my backfire device a little higher than the 50 lb or it won't turn the motor. I have resigned to live with the situation, but have broken 4 or 5 sprags over the last 15 years. With the alarming increase in price on these parts, I have done some extensive searching. It appears there are three manufacturers. Renold P/N REGP4127 (3C), an 18 element device with a rating of 224 newton-meters. Ringspann (Borg-Warner) P/N BWX1310145 (3C), a 14 element clutch with a rating of 180 newton-meters. And Steiber P/N DC 4127 (3C) with 18 elements and a rating of 450 newton-meters.

Unfortunately, I have not found a distributor willing to order these at a price that would be any significant savings over the Norton dealers.
 
L.A.B. said:
Norvil Motorcycles won't warranty the sprag assembly, unless all three parts (sprag, engine sprocket, starter gear) are all replaced together.

"Please note, if you need to replace any of the following, you will need to replace ALL of the following at the same time:-
Sprag Clutch (064733)
Sprocket (064681)
Gear Assembly (064731)
The reason for this is that they all wear at the same rate and failure to replace them together often leads to premature failure of the new part
For this reason, there is no warranty on any of these three parts unless they are replaced together (normal warranty rules apply for parts that are manufactured incorrectly e.g if a part is faulty upon receipt, it will still be exchanged under warranty)

If you are suffering from premature failures of your sprag, then you may have an issue with your anti-backfire device, please phone out tech line"
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On my rebuild I stuck the old one back in, which was an 18 tooth so it must have been changed along the way. I have a brand new 18 tooth on the shelf waiting to take a ride in the primary when the other bites the dust. They must have really jumped in price since I paid $85 two years ago for a brand new 18 tooth version from Walridge.
 
Coco said:
L.A.B. said:
Norvil Motorcycles won't warranty the sprag assembly, unless all three parts (sprag, engine sprocket, starter gear) are all replaced together.

"Please note, if you need to replace any of the following, you will need to replace ALL of the following at the same time:-
Sprag Clutch (064733)
Sprocket (064681)
Gear Assembly (064731)
The reason for this is that they all wear at the same rate and failure to replace them together often leads to premature failure of the new part
For this reason, there is no warranty on any of these three parts unless they are replaced together (normal warranty rules apply for parts that are manufactured incorrectly e.g if a part is faulty upon receipt, it will still be exchanged under warranty)

If you are suffering from premature failures of your sprag, then you may have an issue with your anti-backfire device, please phone out tech line"
Click to expand...

On my rebuild I stuck the old one back in, which was an 18 tooth so it must have been changed along the way. I have a brand new 18 tooth on the shelf waiting to take a ride in the primary when the other bites the dust. They must have really jumped in price since I paid $85 two years ago for a brand new 18 tooth version from Walridge.
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Seems I jinxed myself. Sprag failed just after I sealed the pimary cover with RTV and a fresh gasket. I'll tear it open today to confirm but I'm pretty darn sure my 18 pawl sprag bit the dust.
 
that steiber looks good (from specs at least). How much do they cost?

I'm waiting to see how my 35 year old sprag does :lol: I can foresee selling the starter I bought to fit a belt drive :?
 
Ron,

The Stieber sprag DC 4127 (3C) is listed on their website at a torque spec of 224 N-m, not 450. This makes it comparible to the two others you cited. Is this a typo, or is there another Stieber sprag out there? Could you give us any info on the distributors you found?

BTW, Walridge lists the replacement sprag at $150US, although I don't know if it is an "improved" 18-cog version. Still expensive, but an improvement over other sources.

When I rebuilt my Mk3 last year, I sent the sprag mating parts and backfire unit to Fred at Old Britts for evaluation. The backfire unit was a bit low at 35 lbs, but Fred thought it was adequate for a stock Mk3. I replaced the sprocket and sprag at his recommendation. As I run a Pazon and don't have a backfire problem, this combination has worked well so far (I'm looking around for some wood to knock). I still kick the bike over from time to time, just for the pure hell of it, but use the E-start 90% of the time. Your comment about having two sprag failures over several years tells me that my experiences so far may be a bit optimistic.
 
Ron,

The Stieber sprag DC 4127 (3C) is listed on their website at a torque spec of 224 N-m, not 450. This makes it comparible to the two others you cited. Is this a typo, or is there another Stieber sprag out there? Could you give us any info on the distributors you found?

BTW, Walridge lists the replacement sprag at $150US, although I don't know if it is an "improved" 18-cog version. Still expensive, but an improvement over other sources.

When I rebuilt my Mk3 last year, I sent the sprag mating parts and backfire unit to Fred at Old Britts for evaluation. The backfire unit was a bit low at 35 lbs, but Fred thought it was adequate for a stock Mk3. I replaced the sprocket and sprag at his recommendation. As I run a Pazon and don't have a backfire problem, this combination has worked well so far (I'm looking around for some wood to knock). I still kick the bike over from time to time, just for the pure hell of it, but use the E-start 90% of the time. Your comment about having two sprag failures over several years tells me that my experiences so far may be a bit optimistic.
 
L.A.B. said:
Norvil Motorcycles won't warranty the sprag assembly, unless all three parts (sprag, engine sprocket, starter gear) are all replaced together.

"Please note, if you need to replace any of the following, you will need to replace ALL of the following at the same time:-
Click to expand...


I replaced only the sprag on my Mark III that I have owned since 1975 in the late 80s. I bought two OEM sprags at the time and I have not needed to use the second one yet.
 
I finally got all of the E-start components together and the primary buttoned up. Hit the started button so I could bask in the glory of my work and... nothing. The starter solenoid is good, but the starter itself doesn't spin up. I am guessing something electrical. Could it just be coincidence that when the sprag clutch failed something electrical also failed?
-paul
 
c.cito said:
I finally got all of the E-start components together and the primary buttoned up. Hit the started button so I could bask in the glory of my work and... nothing. The starter solenoid is good, but the starter itself doesn't spin up. I am guessing something electrical. Could it just be coincidence that when the sprag clutch failed something electrical also failed?
-paul
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Can you hear anything? A click or something?
 
c.cito said:
I finally got all of the E-start components together and the primary buttoned up. Hit the started button so I could bask in the glory of my work and... nothing. The starter solenoid is good, but the starter itself doesn't spin up. I am guessing something electrical. Could it just be coincidence that when the sprag clutch failed something electrical also failed?
-paul
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Theres something amiss with the motor or the starter gears are bound up with something.If Im not mistaken you will have to reopen the primary anyway to pull the motor so all will be revealed.Please let us know what happens here Im one of many thats following this thread to solve this starter/sprag issue once and for all.
 
The solenoid under the seat clicks when the starter button is pushed, but the starter motor does nothing... I just spent a week getting my '75 R90/6's starter issues resolved (multiple failures: right bar switch cluster AND a weak-but-not-failed starter relay), and now this. IF the starter motor was bound up, wouldn't it at least groan or something when energized? I guess it might not if it were locked solid. I guess I'll tear into the primary again and have a look. This bike has spent 2 months up on the lift and precious riding time is a'wasting!
-paul
 
c.cito said:
The solenoid under the seat clicks when the starter button is pushed, but the starter motor does nothing... I just spent a week getting my '75 R90/6's starter issues resolved (multiple failures: right bar switch cluster AND a weak-but-not-failed starter relay), and now this. IF the starter motor was bound up, wouldn't it at least groan or something when energized? I guess it might not if it were locked solid. I guess I'll tear into the primary again and have a look. This bike has spent 2 months up on the lift and precious riding time is a'wasting!
-paul
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75 E-Start Sprag clutch
 
c.cito said:
The solenoid under the seat clicks when the starter button is pushed, but the starter motor does nothing... I just spent a week getting my '75 R90/6's starter issues resolved (multiple failures: right bar switch cluster AND a weak-but-not-failed starter relay), and now this. IF the starter motor was bound up, wouldn't it at least groan or something when energized? I guess it might not if it were locked solid. I guess I'll tear into the primary again and have a look. This bike has spent 2 months up on the lift and precious riding time is a'wasting!
-paul
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I did exactly the same repair on my other bike (XS650) with the same result.On re-entry I discovered a washer that was supposed to be behind the clutch basket fell in and got meshed up in the starter gears.Its a relief in a way as otherwise it would have been loose in the primary and could have done alot more damage.Hopefully you will figure this out I'm tired of kicking these bikes as the kickback makes me nervous.
 
Put a test light or voltmeter on the cable located on the starter. If the light works or voltage shows when you hit the button, then the solenoid is OK and your problem is in the starter. I would then pull the starter out of the case so the gear is not engaged and with the starter case grounded hit the button again. If the starter spins, then your problem is likely in the primary.

If your solenoid is bad, go to your local auto parts store and get a Ford firewall mount solenoid for a '90's Mustang or F150. If it has a diode protected spade as well as a low amperage switch lead, it will still work, you just won't use the diode protected spade. The Ford unit is identical to the Prestolite unit Norton used.
 
The Stieber sprag DC 4127 (3C) is listed on their website at a torque spec of 224 N-m, not 450. This makes it comparible to the two others you cited. Is this a typo, or is there another Stieber sprag out there? Could you give us any info on the distributors you found?
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Sorry for the late reply. I somehow missed your post. Of course, 224 n-m is correct. I took this off some notes I took over a year ago. I don't have the information on the distributors any longer. I found them from the manufacturers websites, Renold, Steiber, and Rennspann.
 
swooshdave said:
c.cito said:
The solenoid under the seat clicks when the starter button is pushed, but the starter motor does nothing... I just spent a week getting my '75 R90/6's starter issues resolved (multiple failures: right bar switch cluster AND a weak-but-not-failed starter relay), and now this. IF the starter motor was bound up, wouldn't it at least groan or something when energized? I guess it might not if it were locked solid. I guess I'll tear into the primary again and have a look. This bike has spent 2 months up on the lift and precious riding time is a'wasting!
-paul
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75 E-Start Sprag clutch
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ehh yes, as above really ..............................KICK IT !!!!!!!!!
 
Yeah, having the kicker IS an option, but I really would like everything to work as it should. Testing the starter will have to wait until after the holiday. It has to be something simple, the whole e-start system is pretty basic. Before I tore things apart the starter would spin-up but not engage the sprag. So it's gotta be something I either did or missed... that's usually the problem.
-paul
 
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