# New Coupler Design 8k rpm



## cruisin (Jun 3, 2009)

This is the new coupler design that was used on a AC-50 in excess of 8k rpm smooth as silk. Only 2" in diameter all steel keeps the mass down allowing the higher rpm's without any vibration. The shop that is doing these can do any shaft motor to anytranny using the clutchless design. They also make adapters for the clutch type to convert to clutchless. If anybody is interested I can provide the contact and details.


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## esoneson (Sep 1, 2008)

This looks like the design from heaven. 

Clean and simple.

Hopefully the strength is there too.

I suspect all we have to do is provide a clutch disc and motor shaft specs.

Where do they sit with cost? 3, 4, 5 hundred?

Thanks for posting, this is a great lead.

Eric


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## cruisin (Jun 3, 2009)

esoneson said:


> This looks like the design from heaven.
> 
> Clean and simple.
> 
> ...


If you provide the motor shaft size or motor model, a clutch disk or hub and the total length of coupler, their price is about $250.00 which I thought was real resonable because of the quality of the work.


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## dtbaker (Jan 5, 2008)

cruisin said:


> If you provide the motor shaft size or motor model, a clutch disk or hub and the total length of coupler, their price is about $250.00 which I thought was real resonable because of the quality of the work.


you said 'clutchless' design n the first post..... which is it? or are you saying they use the splined hub from the original clutch disc?


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## JRP3 (Mar 7, 2008)

Probably the splined hub from the clutch.


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## EVfun (Mar 14, 2010)

I'm a bit concerned about the welding done next to the clutch splines. The heat from welding could destroy the heat treatment and allow the splines to fail down the road. 

My couple is similar is design, but I used a input to main shaft coupler (same splines as the clutch disc) turned down to 1.125 inches and with a shallow 1/4 inch keyway cut. This is then slide inside one end of a Ruland CLC-18-18-F and the motor shaft into the other side. According to Ruland this is only suitable for 4500 rpm, but I have had mine to 7000 rpm without issue. I had a controller fail and dump all the current Optimas could dish out into a Prestolite motor and the couple was not harmed (I'm guess around 280 ft-lb of torque.) 

I've thought about something similar only with an aluminum hub designed to bolt accept the center of a rigid clutch hub on one side and the Ruland coupler on the other. This hub could then have a bore down the center to support the pilot shaft. The pilot shaft should be supported with most transmissions, but doesn't need a bearing with a clutchless hub (because it won't rotate relative to the hub.)


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## cruisin (Jun 3, 2009)

EVfun said:


> I'm a bit concerned about the welding done next to the clutch splines. The heat from welding could destroy the heat treatment and allow the splines to fail down the road.
> 
> My couple is similar is design, but I used a input to main shaft coupler (same splines as the clutch disc) turned down to 1.125 inches and with a shallow 1/4 inch keyway cut. This is then slide inside one end of a Ruland CLC-18-18-F and the motor shaft into the other side. According to Ruland this is only suitable for 4500 rpm, but I have had mine to 7000 rpm without issue. I had a controller fail and dump all the current Optimas could dish out into a Prestolite motor and the couple was not harmed (I'm guess around 280 ft-lb of torque.)
> 
> I've thought about something similar only with an aluminum hub designed to bolt accept the center of a rigid clutch hub on one side and the Ruland coupler on the other. This hub could then have a bore down the center to support the pilot shaft. The pilot shaft should be supported with most transmissions, but doesn't need a bearing with a clutchless hub (because it won't rotate relative to the hub.)


What you see in the pictures is clutchless. There is no damage to the splines from heat created from the small amount of welding. The clutch spine is also connected with 4 pins to the steel coupler. No vibration and very durable. The picture on the left is the old design made of aluminum and about 6" in diameter. This has proved to be troublesome due to the larger diameter causing vibration. Wear to the aluminum hub on the motor shaft over a period of time has been found to be a more serious problem, resulting in vibration and noise. Retaining the springs on the clutch disk for the coupler was found not to be any benifit at all.


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## DIYguy (Sep 18, 2008)

cruisin said:


> What you see in the pictures is clutchless. There is no damage to the splines from heat created from the small amount of welding. The clutch spine is also connected with 4 pins to the steel coupler. No vibration and very durable. The picture on the left is the old design made of aluminum and about 6" in diameter. This has proved to be troublesome due to the larger diameter causing vibration. Wear to the aluminum hub on the motor shaft over a period of time has been found to be a more serious problem, resulting in vibration and noise. Retaining the springs on the clutch disk for the coupler was found not to be any benifit at all.


EVfun is correct. The splines will almost certainly fail. It will take a thousand miles or so. . but they will strip.


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## JRP3 (Mar 7, 2008)

I've seen plenty of similar couplers, mine included, that have not failed. I've got about 6K miles on mine, and go up to 7,500 RPM. I really doubt the splines will get hot enough to take out the heat treatment.
Pressed in and welded:


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## DIYguy (Sep 18, 2008)

JRP3 said:


> I've seen plenty of similar couplers, mine included, that have not failed. I've got about 6K miles on mine, and go up to 7,500 RPM. I really doubt the splines will get hot enough to take out the heat treatment.
> Pressed in and welded:


You can doubt all you want. If you got away with it, ur lucky. Perhaps your car will take longer with less power. RPM is not the issue. Torque and shock load are what lead to this failure. I have had two fail for this reason and changed design, I know another who had his fail for the same reason. My background is Welding Engineering and I took steps to lessen the impact of heat on annealing and still had the failures.

A couple other points. It was mentioned that the springs (other design) have no impact. I disagree with this and the softening can be clearly felt when engaging the drive from a stop. Another issue to be aware of is that with the solid design (no clutch springs) there is no need to pilot bearing support the trans input shaft. When using the design that utilizes springs, the clutch centre can float slightly on many of the design./models so using a pilot bearing to centre and support the trans input shaft becomes an issue and is the reason behind some vibration that is tough to track down.

edit, just looking at your pic vs the previous ones. JRP, your splines are larger/deeper. The other one has many smaller ones. The smaller ones will fail easier/sooner due to area/strength. Mine was like this.


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## cruisin (Jun 3, 2009)

DIYguy said:


> EVfun is correct. The splines will almost certainly fail. It will take a thousand miles or so. . but they will strip.


Can you back up your statement that they have and will fail? Show us some pictures of the failed splines. We have been using the clutchless steel couplers since late 1970 without any problems that you talk about. I would sure like to know what you base your results on. This design has also been used on a couple of EV dragsters without any failures. Your failures were probably from homemade adapters that were impropery lined between the tranny shaft and the motor shaft. Clutch type adapters are another story with more problems. Awaiting some pictures from you on the failures.


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## DIYguy (Sep 18, 2008)

You can see the coupler that I made and how I did it on my build thread here. 
.http://www.diyelectriccar.com/forums/showthread.php/good-ohmn-here-we-go-23492.html

I made a second one that looked very similar but with even more precautions. Both stripped the splines. The first one lasted about 2000 km. The second one was less. I don't have any pictures of the failed ones. I'm not bragging here . . lol, my design failed. 
Rob (RKM) liked my method and design and used it on his Miata build. You can see pics of his on his thread also. His failed the same way mine did. 
Since you ask for proof, I assume you are suggesting that I am not being truthful??? I have no reason to make it up. 
Regarding mis-alignment, I doubt that would ever cause a spline to strip. In my case, I know for sure that it isn't mis-alignment because I made a new coupler with the clutch centre including springs and kept the same adaptor so motor/trans has the same mounting relationship. I have 1bout 10,000 km on this version with no issues. Pretty conclusive. 
I'm pretty sure Rob's case is exactly the same. You can contact him if you like and ask him.

There are some variables that can contribute to this failure mode. Type and size of the original splines. Amount of heat (welding process) used and of course the time (time at temperature). Original grade and temper of steel used. Weld procedure (method) used. (Back stepping, wait between welds, cooling time etc). There are more. My point is, there is significant risk with this method. I wouldn't do it again myself. I don't like pulling my motor/trans apart or calling a tow truck.

But hey, it's a free country. . do what you like.


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## jehan12413 (Feb 4, 2010)

One thing which no one has mentioned is weather the failure is limited to the spline on the coupler or is the input shaft also damaged? Originally both the clutch spline and input shaft spline were hardened so if the failure is due to loss of hardening of the adapter spline it will be evident by the damage on that part. If buth parts are equally damaged then there is a different cause for the failure!
Personally I would never consider welding a heat treated part and then not having it re hardened afterwards. Several years I made several adapters just like the welded one above then had them re heat treated and have not had a single failure.


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## DIYguy (Sep 18, 2008)

jehan12413 said:


> One thing which no one has mentioned is weather the failure is limited to the spline on the coupler or is the input shaft also damaged? Originally both the clutch spline and input shaft spline were hardened so if the failure is due to loss of hardening of the adapter spline it will be evident by the damage on that part. If buth parts are equally damaged then there is a different cause for the failure!
> Personally I would never consider welding a heat treated part and then not having it re hardened afterwards. Several years I made several adapters just like the welded one above then had them re heat treated and have not had a single failure.


In both cases for me, (and also for RKM I believe) the coupler spline was the only part with damage. The input shaft was fine. This input shaft was not subjected to heating.


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## cruisin (Jun 3, 2009)

DIYguy said:


> In both cases for me, (and also for RKM I believe) the coupler spline was the only part with damage. The input shaft was fine. This input shaft was not subjected to heating.


 
If you experienced that kind of failure, I can tell you by experience it is from a homemade improperly aligned adapter plate. If properly aligned, there is no wear being produced between the coupler and spine if both metals have the same characteristics. High tech welding will have no effect on the spline welded into the coupling. The notion that is does is wrong. Being in this business for over 50 years has taught me a lot. Better check your adapter plate my friend, using lasers.


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## DIYguy (Sep 18, 2008)

cruisin said:


> If you experienced that kind of failure, I can tell you by experience it is from a homemade improperly aligned adapter plate. If properly aligned, there is no wear being produced between the coupler and spine if both metals have the same characteristics. High tech welding will have no effect on the spline welded into the coupling. The notion that is does is wrong. Being in this business for over 50 years has taught me a lot. Better check your adapter plate my friend, using lasers.


I've explained how my coupler failed. I'm sorry that you don't like it, but it is what it is and it has nothing to do with adaptor misalignment as my adaptor is still in place and being driven daily with 10,000 km and counting. "that kind of failure" is a stripped spline resulting from heat affected hardened steel in the welded coupler. 
Perhaps you can explain to me what "high tech welding" is but before you do, make sure that you do your homework since I have a degree in Welding Engineering.


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## cruisin (Jun 3, 2009)

DIYguy said:


> I've explained how my coupler failed. I'm sorry that you don't like it, but it is what it is and it has nothing to do with adaptor misalignment as my adaptor is still in place and being driven daily with 10,000 km and counting. "that kind of failure" is a stripped spline resulting from heat affected hardened steel in the welded coupler.
> Perhaps you can explain to me what "high tech welding" is but before you do, make sure that you do your homework since I have a degree in Welding Engineering.


 
Since we have been using this design in dragsters for over 40 years without a failure like only you are having, I would suggest you should look at what you are doing wrong with or without a degree.


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## DIYguy (Sep 18, 2008)

cruisin said:


> Since we have been using this design in dragsters for over 40 years without a failure like only you are having, I would suggest you should look at what you are doing wrong with or without a degree.


Yes, thanks... I did look at it and resolved it. I was just sharing my experiences.
One question for you though.. . if you have been using this design for over 40 years without a failure, why did you title this thread and introduce this coupler as a "New Coupler Design". . ?? Just wondering. .


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## Ziggythewiz (May 16, 2010)

I'm sure many people have experienced coupler failure, myself among them. Whether caused by heat or just wear is up for debate.


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## cruisin (Jun 3, 2009)

DIYguy said:


> Yes, thanks... I did look at it and resolved it. I was just sharing my experiences.
> One question for you though.. . if you have been using this design for over 40 years without a failure, why did you title this thread and introduce this coupler as a "New Coupler Design". . ?? Just wondering. .


2" coupler instead of the 3" coupler used for many years. Also, changed the set screw arrangement to 3 which is what CANEV did as well.


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## DIYguy (Sep 18, 2008)

Hey, if they are working for you, it's all good. The proof is in the application. Mine didn't.
It appears as though yours was welded with GTAW (commonly called TIG). This process can (depending on weld procedure) have a lower heat input which will be an advantage for this issue. GTAW is not commonly used on thick sections though for a few reasons. One is that it is not economical since it is so slow. Another is due to it's rather shallow penetration, which would require multiple passes for thicker sections. (potentially impacting the benefit of lower heat input . . again depending on method, inter pass temps etc). If the thicker sections (and I mean thicker than gauge sheet like this is) are welded in a single pass without joint preparation, you risk weld failure. 
Anyways, point being, welding heat treated components is risky. The professional way to ensure a quality welded product is qualify the procedure and the if manually done, the welder. This is done by documenting all parameters and then proving by testing. (could be destructive like macro or non-destructive like ultrasonics or x-ray for example) For hardenable components, Vickers micro-hardness testing can be done across the sectioned weld and into the parent metal to identify brittle martensitic structures and heat affected zone hardness. Anyways, the idea is to qualify the procedure and document it and replicate it to have the best chance for repeated success. Even if you could just do a Rockwell hardness test in few places on the part with splines, it will tell you something useful. Hope that is of some use to someone.


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## cruisin (Jun 3, 2009)

DIYguy said:


> Hey, if they are working for you, it's all good. The proof is in the application. Mine didn't.
> It appears as though yours was welded with GTAW (commonly called TIG). This process can (depending on weld procedure) have a lower heat input which will be an advantage for this issue. GTAW is not commonly used on thick sections though for a few reasons. One is that it is not economical since it is so slow. Another is due to it's rather shallow penetration, which would require multiple passes for thicker sections. (potentially impacting the benefit of lower heat input . . again depending on method, inter pass temps etc). If the thicker sections (and I mean thicker than gauge sheet like this is) are welded in a single pass without joint preparation, you risk weld failure.
> Anyways, point being, welding heat treated components is risky. The professional way to ensure a quality welded product is qualify the procedure and the if manually done, the welder. This is done by documenting all parameters and then proving by testing. (could be destructive like macro or non-destructive like ultrasonics or x-ray for example) For hardenable components, Vickers micro-hardness testing can be done across the sectioned weld and into the parent metal to identify brittle martensitic structures and heat affected zone hardness. Anyways, the idea is to qualify the procedure and document it and replicate it to have the best chance for repeated success. Even if you could just do a Rockwell hardness test in few places on the part with splines, it will tell you something useful. Hope that is of some use to someone.


Actually, one could just do some good tack TIG welds since there are 4 pins preventing any rotation of the clutch spline as well as the 1/4" keyway. The weld would just keep the clutch spline from seperating from the coupler. A set screw in the coupler to the keyway would also prevent the seperation. I may even suggest that the weld is not totally necessary, just on the cautious side.


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## JRP3 (Mar 7, 2008)

I'm not welder or metallurgist but looking at the picture I would think that the weld is far enough away from the splines that if reasonable care were taken and the welding was done in stages that not enough heat would get to the splines to remove the hardness. That's a pretty hefty chunk of metal for the heat to travel through.


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## cruisin (Jun 3, 2009)

JRP3 said:


> I'm not welder or metallurgist but looking at the picture I would think that the weld is far enough away from the splines that if reasonable care were taken and the welding was done in stages that not enough heat would get to the splines to remove the hardness. That's a pretty hefty chunk of metal for the heat to travel through.


True, also a shaft is inserted into the spline when welding takes place drawing heat away from the welded area.


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