Lehner motors just don't last long

[kfxguy]

I don't intent this thread to be an attempt at starting an argument, just to share my personal experience. From what I've heard, Lehner motors are supposed to be the bees knees when it comes to motors. Well I've experienced the opposite. There's a lot to explain but the short of it is I've had two myself. One of which the shaft moved and allowed the magnets to slip. The other one I didn't have enough runs on it to fail before sinking that boat, but without a doubt I feel now that it would have failed anyway. The other two I've dealt with were in customers boats, one of which contacted me today (why I'm writing this because not only am I agitated but I feel like this may save someone some hard earned cash if they were considering buying one) and let me know the shaft slipped in his. The other person I was referring to, his shaft slipped also. So three of them did pretty much the same thing with three different people. Yea one of them was slightly abused (running 9s on an 8s motor although lehners website says you can spin them higher for short periods of time which is what he did only once) so to me there's a common denominator. I, along with a couple friends of mine have abused Neu and TP motors and have had only one fail out of a countless amount between us. The failure was a tp motor (early design) that was 1720kv running on 8s. So we were knowingly abusing it to see what it could handle. At $119 and it fails, who cares.( I've not had a failure when running within the limits of the motors, however.) When you spend $400+ on a motor you kinda expect more that 20-30 runs before the shaft slips inside the magnets. Overall my assessment is they make good power but they are not some voodoo magic to make you go warp speeds. I've gone faster with neu motors anyway. Also the warranty on a lehner motor....what warranty? I know this may piss some people off, but I'm sharing my true experience. You may have had good luck with them, all I can say to that is you don't run your boats as much as I do and my customers/friends do or you've been lucky and I haven't. honestly I only had around a months worth of weekends running my boat with mine anyway, so why fail so quickly? Do these ****s need a thrust bearing or something? Maybe they are good for saw use only.....but that's all I was doing with mine and I went within a few mph of the Lehner with a much lower kv neu on the same voltage. I'll just stick with what's been more reliable in my experience. Sorry I just had to get it off my chest. My feelings have been hurst on this subject for a while now and when my customer contacted me today, that just added to it. Here's a pic: also, we compared before and after rear pics to see how much the shaft was sticking out the back to rule out a slipped collet.





Here's when it was new. Look close at how far the shaft sticks out







And here's how it is now. You can easily tell its stick out further. Not good.

[NativePaul]

Maybe they are good for saw use only.....but that's all I was doing with mine

They are definitely not for SAW use only, they are easily the most popular high end motor here for Naviga racing which has a 6 minute runtime, and I know several people that have been running the same Lehner for over a decade. I can't recall one running a thrust bearing, certainly the majority of them don't. We use their smaller motors however 10, 15 & 19 series, and SAWs aren't popular here, no-one in the UK is running as fast as you.

I think there is enough of them running here that I can safely say that they are not all having good luck with bad motors, you are definitely having bad luck, but on three out of 4 motors there must be something more than bad luck there.

It is possible they had a bad batch of glue used in 22 series but if they were getting returns from all over I would expect them to stand behind their product more, or even do a recall. Maybe the short burst of very high power gets the lightweight rotor which cant be effectively watercooled or measured, hot enough to the effect the glue, whereas a heavier rotor from an equivalent multipole rotor will never spike in temperature quite as high, given the same power and losses, I notice that the can in the picture is the sealed type not the aircooled type that do cool the rotor and I have seen in other SAWs boats recently.

Ze Germans seem to do OK with them in SAWs, Anderas Lehner is a SAW racer himself (although the boat of his that I saw was powered by a 19 series), maybe they are OK for 2 runs of SAWs but the heat buildup of a 3rd run of SAWs like fun running builds up enough heat to do the damage.

[Fluid]

I can't argue with the OP's experiences, but they are very different than mine and those of fellow club members. The most extreme example, one guy has raced the same 1900 series motor in his Q Sport Hydro for over six years with no problems; this is in one mile sprint races against other fast boats regularly. Other members who have run Lehners have had no problems either. This is not zip-zip SAW runs, but full three-heats-a-day racing.

i don't know where the idea started that Lehners were the most powerful motors, or that they hold some magic properties - of course they do not. But with over a decade's experience with them and around them I can say that they are very good motors compared to lower priced competition. Note I did not say better. I do know that Lehner measures the Kv differently than other motor makers, and folks who substitute a Lehner for another brand with the same Kv will have problems. When the 4-pole Neu motors cane out we discovered that we needed to increase the Kv by 15-25% for similar performance. A direct change from a Neu to a Lehner will result in excessive Kv with poor motor performance and high stress on the motor.

Admittedly, all my experience has been with older Lehners. It is certainly possible that their quality has slipped - it certainly has with Neu in the last few years. If the OP wants to quit using Lehners and go with TP or Neu, based on his experience that certainly makes sense.



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[kfxguy]

They are definitely not for SAW use only, they are easily the most popular high end motor here for Naviga racing which has a 6 minute runtime, and I know several people that have been running the same Lehner for over a decade. I can't recall one running a thrust bearing, certainly the majority of them don't. We use their smaller motors however 10, 15 & 19 series, and SAWs aren't popular here, no-one in the UK is running as fast as you.

I think there is enough of them running here that I can safely say that they are not all having good luck with bad motors, you are definitely having bad luck, but on three out of 4 motors there must be something more than bad luck there.

It is possible they had a bad batch of glue used in 22 series but if they were getting returns from all over I would expect them to stand behind their product more, or even do a recall. Maybe the short burst of very high power gets the lightweight rotor which cant be effectively watercooled or measured, hot enough to the effect the glue, whereas a heavier rotor from an equivalent multipole rotor will never spike in temperature quite as high, given the same power and losses, I notice that the can in the picture is the sealed type not the aircooled type that do cool the rotor and I have seen in other SAWs boats recently.

Ze Germans seem to do OK with them in SAWs, Anderas Lehner is a SAW racer himself (although the boat of his that I saw was powered by a 19 series), maybe they are OK for 2 runs of SAWs but the heat buildup of a 3rd run of SAWs like fun running builds up enough heat to do the damage.

You know Paul, you might be on to something. None of these motors that had failures had the fan. Maybe it just needs it? I hate to bash on something like this, I can't remember when I've ever posted a thread like this before, but being that It wasn't just once it happened, the same thing happened between three different units (all 22 series tho) and it's hard to swallow sure a huge loss in a short amount of time, I felt like I needed to get it off my chest.

[kfxguy]

I can't argue with the OP's experiences, but they are very different than mine and those of fellow club members. The most extreme example, one guy has raced the same 1900 series motor in his Q Sport Hydro for over six years with no problems; this is in one mile sprint races against other fast boats regularly. Other members who have run Lehners have had no problems either. This is not zip-zip SAW runs, but full three-heats-a-day racing.

i don't know where the idea started that Lehners were the most powerful motors, or that they hold some magic properties - of course they do not. But with over a decade's experience with them and around them I can say that they are very good motors compared to lower priced competition. Note I did not say better. I do know that Lehner measures the Kv differently than other motor makers, and folks who substitute a Lehner for another brand with the same Kv will have problems. When the 4-pole Neu motors cane out we discovered that we needed to increase the Kv by 15-25% for similar performance. A direct change from a Neu to a Lehner will result in excessive Kv with poor motor performance and high stress on the motor.

Admittedly, all my experience has been with older Lehners. It is certainly possible that their quality has slipped - it certainly has with Neu in the last few years. If the OP wants to quit using Lehners and go with TP or Neu, based on his experience that certainly makes sense.



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In a way I almost feel bad for posting this because there's been some reputable people running them and not having problems. Not sure why this has happened to me but it wasn't a cheap learning experience. The funny thing is I replaced the lehners in two of the boats with neus and they are going through the same sort of use and no failure yet.

Also Paul, something else I just thought about because of what you posted....... If you have the fan in the motor that would make the rotor longer and have more grip area on the shaft to keep it from pushing out the rotor. Might be the reason because I had to be weird and not get fans in mine. My thought on that was the fact that if it had a fan it would create more drag from moving air. I was probably over thinking it.

[NativePaul]

I would be gutted too if I were you.

I have 2 (both bought used, I am on a tight budget) and neither have fans, I think that if I was to but new they would be fanless too, as I agree that the fan must add drag and increase the IO, but then I can only pull 45A ,so half an amp of IO will be 1% less power to the prop, for SAWs type running it will make a lot less difference if any.

I have no idea if the fan is part of the rotor thus increasing glue area, or a separate piece. I don't imagine that it is as simple as lacking glue surface area though as a wire drive has the same power going through it, has a much smaller glued area, on a smaller diameter, and they hold up fine.