[hybridreams]

Hello,

As the subject line suggests: I'm looking for torque specifications for attaching the flywheel to the taper lock on my WarP9 motor. Any ideas?

I've contacted Netgain for any insight, but they promptly washed their hands of it, saying I should refer to whomever I purchased the motor from. The motor was purchased used, but it originally was purchased from CanEV. So I did reach out to them, but...either they are ignoring my question (because they also don't want to take responsibility, or don't know the answer), or they are crazy busy (I suspect the latter since there has been a lot of hype around conversions in Vancouver recently).

Anyone have some numbers?

Alternatively, anyone suggest a different coupler? (And if it still requires a flywheel, I still need torque specs--those things are heavy and rotate fast!

Thanks!

 

[hybridreams]

Any suggestions?

 

[remy_martian]

If it's a steel flange, I'd go with the OEM's (you don't say what vehicle which is annoying) torque spec using the high grade OEM bolts.

 

[hybridreams]

Yes, this was my first thought. However, it seems counter-intuitive to me, since the OEM specs are for mounting the FW to the ICE, whereas of course this is an electric motor (operating at much higher RPM's and torque).

The vehicle is a 1987 Dodge Dakota; however, that is not much help, because the transmission is a T5 Borg Warner of the kind used in a "GM 1985 S-Truck 2.8 V6". So I suppose I could use the specs for a '85 S10, but like I said, while it was my initial thinking, it does seem odd considering it is not technically mounted to a ICE.

But from your comment, I gather this is the typical approach for conversions?

 

[remy_martian]

The typical backyard approach is probably to use whatever bolt fits and use a cheater pipe "cuz tighter is better."

Motor torque is somewhat irrelevant to bolt torque. If you have substantial torque over the stock application, the flywheel bolts will fail in shear (then you can go to the casting call for Lt Dan in a Forest Gump play and be legit). The clutch is supposed to slip to protect the system from loading the flywheel bolts that high.

 

[remy_martian]

😬

Note that a clutch pressure plate has weights on it, so not only may you have a flywheel bolt problem due to torque, but excessive RPM means higher pressure plate forces which means that mechanical fuse of clutch slippage is gone for the flywheel bolts and you could frag the stock cast iron pressure plate with the high forces.

I also feel sorry for the input shaft and cluster shaft bearings on your T5....they also are not rated for high RPM much beyond the ICE speeds. It may work, but for how long?

If you are constantly running high motor RPM, I'd invest in a scattershield or at least a blanket.

 

[hybridreams]

Motor torque is somewhat irrelevant to bolt torque. If you have substantial torque over the stock application, the flywheel bolts will fail in shear (then you can go to the casting call for Lt Dan in a Forest Gump play and be legit). The clutch is supposed to slip to protect the system from loading the flywheel bolts that high.

Yes, this is precisely my concern...

 

[hybridreams]

😬

Note that a clutch pressure plate has weights on it, so not only may you have a flywheel bolt problem due to torque, but excessive RPM means higher pressure plate forces which means that mechanical fuse of clutch slippage is gone for the flywheel bolts and you could frag the stock cast iron pressure plate with the high forces.

I also feel sorry for the input shaft and cluster shaft bearings on your T5....they also are not rated for high RPM much beyond the ICE speeds. It may work, but for how long?

If you are constantly running high motor RPM, I'd invest in a scattershield or at least a blanket.

Well... maybe the OEM specs are fine. The vehicle was converted in the late 90s and the previous owner said he used to keep the RPMs high (for greater efficiency). Mind you, that was using a Kostov motor, which he destroyed by pushing the RPMs too high...but he didn't mention the flywheel/press.plate having exploded, so maybe it's fine? lol

I should point out that I don't intend to race the vehicle. It's just for commuter/work purposes.

 

[hybridreams]

...geez, now I'm starting to wonder if the bolts are even the issue...should I be using a different flywheel? (Steel, aluminum, chromoly...?)

 

[remy_martian]

The Warp9 is only rated to 5500 RPM. Not like some of the other stuff out there that revs 10 grand, like Leaf, Bolt, Borg Warner, or Tesla (15-18,000).

Where's max efficiency? Revving the snot out of it is not necessarily the highest efficiency point like your pal may have thought.

 

[hybridreams]

https://cdn.shopify.com/s/files/1/1820/0269/files/003_09_01_WarP_9A_Graph.pdf?v=1599243480

I think according to this graph from Netgain that the max efficiency for a WarP9 is around 2500-2800 rpm...?

 

[remy_martian]

ta da!

Seems kinda flat, so gear it for the torque/hp you need.

 

[hybridreams]

ta da!

Alright. Appreciate your bearing with me / guiding me through this process!

To summarize, I am fine to use the stock flywheel and torque them to OEM specs (based on the '85 S10 tranny...which I think I saw online to be around 55lb/ft).

Feeling much more confident about that (and the lower probable need of a scattershield!)

My thanks again!

 

[remy_martian]

You did the math, I just poked at you a bit.

 

[K S]

Regardless of the bolt torque you finally select, use locktabs or safety wire on the bolts, If it is practicable to do so.

 

[hybridreams]

Thank you. I was thinking to use threadlocker. Would that work as effectively?

 

[brian_]

https://cdn.shopify.com/s/files/1/1820/0269/files/003_09_01_WarP_9A_Graph.pdf?v=1599243480

I think according to this graph from Netgain that the max efficiency for a WarP9 is around 2500-2800 rpm...?

Yes, in this idiotic representation of test data, not designed to be convenient for any purpose, the peak of the efficiency curve (of about 94%) occurs when the motor in the test was producing around 50 to 60 lb-ft of torque, and that torque was produced while the motor in the test was (according to the RPM curve) turning at 2500 to 2800 RPM.

That's at full load. At lower load, peak efficiency will be at a different (lower) speed.

The efficiency at full load and high speed doesn't vary much with speed, but the available torque does. The result is that the builder needs to select gearing for performance over the target speed range, not so much for efficiency.

Because of the test method, only the range from nearly unloaded speed (over 5,000 RPM) until the peak torque speed (about 2100 RPM) is tested. The motor works at lower speeds, but the crude test method is unable to cover that speed range.

 

[brian_]

Yes, this was my first thought. However, it seems counter-intuitive to me, since the OEM specs are for mounting the FW to the ICE, whereas of course this is an electric motor (operating at much higher RPM's and torque).

The claim of "much higher RPM's and torque" for the electric motor is very questionable, but it doesn't matter. Tightening the bolts more won't make anything stronger. The bolts should be tightened to the torque which is appropriate for the bolts and the parts being bolted together. If the result is not strong enough, you need a different design, not just a different torque; if the result is stronger than required, okay, that doesn't mean that the bolts should be looser or tighter.

 

[brian_]

The vehicle is a 1987 Dodge Dakota; however, that is not much help, because the transmission is a T5 Borg Warner of the kind used in a "GM 1985 S-Truck 2.8 V6". So I suppose I could use the specs for a '85 S10, but like I said, while it was my initial thinking, it does seem odd considering it is not technically mounted to a ICE.

The flywheel is bolted to the engine, not the transmission. The bolted flange connection is part of the engine specs, not those of the transmission... but if the flywheel you're using is from the GM 2.8 V6, that's the source of flywheel-to-flange bolting specs.