# Max Tranny RPM?



## terrorr (Jul 17, 2017)

*Max Transmission RPM? Will it blow?*

Hi folks. First post but I have learned alot on this forum. 

Just converted an 84 Ford Ranger to EV. It has an AC51 motor 144volt with manual 4 speed tranny.

Drives great and I usually leave it in 2nd or 3rd gear and do not bother shifting.

However, I have a question about the tranny and max rpm.

Lots of discussion about manual transmission, clutchless vs clutch, etc. I know the electric motor can run at higher rpms but what about the tranny?

I notice my transmission tends to get really noisy about 2500 rpm and above. Before with the ICE the revs were always kept around 2000-3000 rpm while up and down shifting. In that range it is not too noisy.

SO isn't the tranny designed for this narrow range? Isn't it bad for the tranny to not shift up and down with the electric motor? At higher rpm (3500-5000, say) the tranny is making alot of noise.

Cheers!

PS changed the oil in the tranny already to see if that would quiet it down but did not make much difference.


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## dcb (Dec 5, 2009)

what kind of noises does it make and at what rpms? Could be motor misalignment/mouinting or?

http://www.procarcare.com/includes/content/resourcecenter/encyclopedia/ch20/20TSclutch.HTML

it isn't really a question of max tranny rpm at these speeds, unless there is something you aren't telling us 

also: https://www.google.com/search?q=84+...rome..69i57.5279j0j4&sourceid=chrome&ie=UTF-8


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## terrorr (Jul 17, 2017)

Let's put aside the noise. I am more curious about the operating range for the transmission.

Can you run the transmission at 5000 rpm for long periods at a time?

Is it made for that?

So for example if I put the truck in 2nd gear and leave it in 2nd gear and drive around town at 50 mph it will be running around 5000 rpm.

If I put the truck in 3rd gear and leave it in 3rd gear and drive around town at 50 mph it will be running around 4000 rpm. That still seems to me too high.

Cheers!


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## dcb (Dec 5, 2009)

why does 4000 rpm seem to high? because of the noise? Normally I wouldn't give sustained 4000 rpm on a gearbox a second thought, provided it wasn't complaining. I can't simply say "It's ok" under these circumstances though. But if you don't want to discuss it or look into it then I guess thats that.


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## madderscience (Jun 28, 2008)

Assuming the motor/transmission alignment is right, then is the noise just gear whine? You are always going to hear more of than in an EV with a transmission just because the engine isn't drowning it out.

You didn't say what you changed the oil to. I like redline superlight shockproof. Its a lightweight full synthetic that does not have the friction modifiers used in most gear oils for posi differentials. 

If you have any way to monitor gearbox temperature, that might be an indicator if something is wrong. If the gearbox is getting hot (assuming you have enough range to drive 30 minutes to an hour at freeway speed) that could be an indicator that it is overspeeding or otherwise having problems.

You can look at changing the rear end gear ratio to allow yourself to run in higher gears (e.g. go from a 4.10 to a 4.77 rear end) and that might allow you to run in a higher gear more of the time. Not sure what the standard rear end in an older ranger is or what others are available but sure the info is out there.


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## electro wrks (Mar 5, 2012)

terrorr said:


> Let's put aside the noise. I am more curious about the operating range for the transmission.
> 
> Can you run the transmission at 5000 rpm for long periods at a time?
> 
> ...


If the Trans. and the motor are properly aligned and assembled with the right oil in the box, the trans. should be fine. Without photos and/or an explanation of the separate parts and how they're put together, we really can't be much help.


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## piotrsko (Dec 9, 2007)

Not sure which version trans you have, toyo ktogo, mitsubishi, whatever. Gen 1 thru 3 were constant mesh and they have straight gears that whine. Mine makes enough noise to be used as a warning device in parking lots, particularly in 4wd low. It wont whine in 4th 2wd hi because that is direct drive. As far as max rpm I don't know. I try to gear it for running at 3000 rpm as that keeps the motor coolest. It is splash lube on the bearings so I suspect they wont like lots of sustained running at 5000 rpm. 

This is old tech. Good enough back then, not so much today


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## terrorr (Jul 17, 2017)

Thanks everyone for your replies.

Sorry, I guess I should have maybe made this two posts - 1) 4speed transmission rpm and what is it designed for 

and b) my tranny noise.

So for the first one I was thinking like this:

The ICE engine and 4 speed tranny are designed to work together. The ICE motor has a different power band than an electric motor and needs the gears to operate within it’s rpm power range. The rpms can spike a bit but usual driving hovers around 2000-2500 rpm.

Cruising speeds around 50 mph the rpms are maybe 3000 rpm. So the tranny never really runs for long periods at 4000 rpm or 5000 rpm because that is not what the ICE runs at.

But now I have the AC51 connected to a tranny designed for the ICE. The AC51 can cruise at 4000 rpm no problem. 

But is it good for the transmission? 

Is it built for higher rpms for long periods at that rpm?

I have read on the forums that many people just leave the vehicle in one gear and drive without shifting. That would be my preference. 

If I leave it in 2nd gear it is better around town in traffic but 3rd gear seems better at higher speeds. So if the rpms are not an issue for the transmission I would leave it in 2nd.

If it is better for the transmission I can reintall the clutch pedal and just shift up and down like before when it had the ICE.

Cheers!


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## terrorr (Jul 17, 2017)

piotrsko said:


> Not sure which version trans you have, toyo ktogo, mitsubishi, whatever. Gen 1 thru 3 were constant mesh and they have straight gears that whine. Mine makes enough noise to be used as a warning device in parking lots, particularly in 4wd low. It wont whine in 4th 2wd hi because that is direct drive. As far as max rpm I don't know. I try to gear it for running at 3000 rpm as that keeps the motor coolest. It is splash lube on the bearings so I suspect they wont like lots of sustained running at 5000 rpm.
> 
> This is old tech. Good enough back then, not so much today


It has the Toyo Koygo. I have should have been more clear when I said noise. It just sounds like gear whine.


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## terrorr (Jul 17, 2017)

Ok sounds like the consensus is the trans should be fine at higher rpms.

As far as the noise, when I bought the truck I drove it a few months and the truck in general was noisy. The motor was loud and it squeaked a bit and rattled etc plus it is a 33 year old truck. I don't think I could hear much of the tranny over the engine.

When I installed the AC51 it was so quiet, it was an amazing difference. So later I started noticing the transmission sounds which I think is just the gear whine.

It runs fine at higher speeds - no vibrations or anything. There is not much sound dampening insulation either so that maybe part of it. I am going to change the oil in the gearbox again with some Lucas oil and see if that helps.

Unfortunately where I live there isn't anyone else with an EV conversion that I can test drive or listen to so I am just on my own. Thanks for your feedback.


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## electro wrks (Mar 5, 2012)

terrorr said:


> When I installed the AC51 it was so quiet, it was an amazing difference. So later I started noticing the transmission sounds which I think is just the gear whine.


OK, this is a clue that something is wrong with the transmission-probably related to how it was put together with the electric motor. If you are willing to accept that and not that the problem is related to the design or limitations of the trans., we can probably help you. Properly mating an electric motor to a trans. is more difficult than most people realize.

If you want some help, please let us how you put the trans. and motor together.


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## terrorr (Jul 17, 2017)

electro wrks said:


> OK, this is a clue that something is wrong with the transmission-probably related to how it was put together with the electric motor. If you are willing to accept that and not that the problem is related to the design or limitations of the trans., we can probably help you. Properly mating an electric motor to a trans. is more difficult than most people realize.
> 
> If you want some help, please let us how you put the trans. and motor together.


Sorry what I meant was the truck ran much quieter with the new electric motor compared to before.

It was then that I could hear other sounds because the ICE wasn't covering them up. The gearbox didn't start making new or louder whining sounds. 

Not trying to dismiss potential problems with the motor/tranny but just trying to eliminate variables and understand the design limits of the gearbox. I do appreciate the help.

The motor was mounted using a kit from CanEV. First I mounted a coupler on the shaft, then an adapter plate, then aligned the tranny to the motor and slide it into position. Slipped in pretty smooth I thought. Spun the motor/tranny by hand, no real resistance or weird sounds. Tightened up the adapter plate. 

Cheers.


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## electro wrks (Mar 5, 2012)

That's a good start for mating the motor to the trans. Did you use the alignment dowels? Does the coupling provided have something to support the end of the trans. input shaft where the pilot bearing would normally ride? The splines alone, without this support, sometimes are a loose fit that might not support the end of the input shaft well enough.

Does this sound like a harmonic noise that has peaks at X RPM, 1/2X RPM, 2X RPM etc.? Have you eliminated the drive-line(drive shaft) as the source of the noise? Does the trans. have a lot of miles on it?


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## piotrsko (Dec 9, 2007)

No, noise is normal for a kyogo.  they have straight cut gears. They have mesh whine. It aint an alignment problem or a bearing problem especially because of the can ev adapter. No synchro effect as they are constant mesh so they don't speed shift. 

If you aren't shifting you can use 70w multi viscosity weight gear oil and it will quiet down some but be a bit stiff cold and use more watts. Im running a 50/50 mix tranny gear oil and that helped a bit.

The real issue is that the v6 was so noisy that is all you heard.


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## terrorr (Jul 17, 2017)

piotrsko said:


> No, noise is normal for a kyogo.  they have straight cut gears. They have mesh whine. It aint an alignment problem or a bearing problem especially because of the can ev adapter. No synchro effect as they are constant mesh so they don't speed shift.
> 
> If you aren't shifting you can use 70w multi viscosity weight gear oil and it will quiet down some but be a bit stiff cold and use more watts. Im running a 50/50 mix tranny gear oil and that helped a bit.
> 
> The real issue is that the v6 was so noisy that is all you heard.


Awesome. Wasn't sure, now I know. Thank you.

So if I leave it in 2nd gear for city driving but occasionally cruise at 50mph that would mean 5000rpm. Would you say that the kyogo gearbox will be ok with that?

Sorry if I keep repeating this theme. It is just I have worked on alot of cars and driven alot of cars and just can't wrap my head around driving down the street at 4000 or 5000 rpm.


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## electro wrks (Mar 5, 2012)

piotrsko said:


> No, noise is normal for a kyogo.  they have straight cut gears. They have mesh whine. It aint an alignment problem or a bearing problem especially because of the can ev adapter. No synchro effect as they are constant mesh so they don't speed shift.
> 
> If you aren't shifting you can use 70w multi viscosity weight gear oil and it will quiet down some but be a bit stiff cold and use more watts. Im running a 50/50 mix tranny gear oil and that helped a bit.
> 
> The real issue is that the v6 was so noisy that is all you heard.


Are you sure this trans. has straight cut gears? I haven't seen a trans. that didn't have helical cut gears(except for the reverse gears and racing versions) for many moons now.


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## brian_ (Feb 7, 2017)

*"Constant mesh", "straight-cut gears", and other transmission characteristics*

The working assumption here seems to be that the transmission is a Toyo Kogyo (Mazda) TK4 (manual 4-speed), which would be normal for a 1984 Ranger. It was used in many Mazdas and Fords, including the small pickups, related SUVs, and even sports cars (Miata, RX-7).

This is a *constant-mesh* transmission, like all automotive transmissions built in my lifetime. That only means that each gear stays in place and engaged with its partner gear all of the time... they're not slid along shafts to engage and disengage with each other. Shifting is instead done by sliding dogs (and synchronizers, in the case of a synchro box) to engage and disengage one gear of each pair from the shaft. Of course this is a synchro box; we're talking about the 1980's here, not the 1940's. 

While the gears of a non-constant-mesh transmission must have *straight-cut* teeth (parallel to the shaft) to allow shifting, a constant-mesh transmission can use straight or helical (spiralling around the shaft) gears. So saying that this is a constant-mesh transmission says nothing about whether the gears are straight-cut (noisy) or helical (quieter).

As electro wrks said, straight-cut gears have been rare (other than for the reverse gear) in production cars for many years, although they are still used in many racing transmissions. Which does the TK4 have? I did find an exploded view (from The Ranger Station's manual transmission page); although the gears appear to be helical, the image is so poor in quality that it is hard to be certain. My guess is helical, but I don't really know. I suspect the noise problem is not due to straight-cut gears.


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## nucleus (May 18, 2012)

Starting in the 60's everything is helical cut, except for reverse. The expensive cars like BMWs had helical gears in reverse. The noise difference is huge. Think of the whining noise many cars make in reverse.


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## dcb (Dec 5, 2009)

re: straight cut and constant mesh. According to this
http://www.drivetrain.com/parts_cat.../ford_3_4_5_speed_reference_material_v26.html

some ford had a straight cut first/reverse sliding gear till 87, and some part of that may be spinning meshed (or viscous coupling). Don't know how the noise relates to load though. (actually with an idler gear, some straight cut part HAS to be meshed, no?)

But we are just reading tea leaves at this point, drive it and cross your fingers, or tear it down and inspect/repair.

TK4, mazda, no mention on that page though.

bit if it IS a tk4, they have an overhaul kit:
http://www.drivetrain.com/parts_cat...ts/toyo_kogyo_4_and_5_speed_overhaul_kit.html


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## piotrsko (Dec 9, 2007)

Oh I'm sorry, I just have one and have been inside it to rebuild it. I didn't google it to see how it works, I use the correct ford service manual. How obsolete.

The gears are cut on an angle, there is no helix curve to the cut. Hence my comment straight cut. Cheap mod to make the gears stronger learned from german WW2 submarine transmission. Since they are constant mesh, you dont care how the shift properties are, that isn't what is changing.


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## dcb (Dec 5, 2009)

https://en.wikipedia.org/wiki/Helix_angle#Helical_gear

says nothing about a curve fyi, are you thinking of hypoid? Or are you saying they just drug the involute cutter in a straight line (on an angle to the axis of rotation, i.e. helix), instead of rotating the gear during the cut, and the teeth are deeper in the middle of the gear or something (how would that even work)? I mean we are talking about circles here, there's gonna be a curve somewhere. Did they not use an involute cutter?


also, my own duh, straight cut are definitely louder when loaded, so hard to imagine a healthy straight cut idler making that much racket when the car is in second.

and does OP know the difference between a whine and a screech?!?


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## electro wrks (Mar 5, 2012)

This is hurting my head to think about this. Name-wise the straight cut gears I'm thinking of are better known as spur gears. piotrsko, I think people are right. The angled teeth need to be in the form of a helix to mesh properly. If the teeth were near perfectly straight, and not in the form of a helix, they would only mesh on the very ends(corners) of the teeth. This would be extremely impractical and undesirable. And, not a design to use in a gearbox.


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## electro wrks (Mar 5, 2012)

We are getting somewhat OT here. terrorr, could you address the questions I asked in post 13. Maybe that will get us back on topic.


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## brian_ (Feb 7, 2017)

dcb said:


> https://en.wikipedia.org/wiki/Helix_angle#Helical_gear
> 
> says nothing about a curve fyi, are you thinking of hypoid?


No, there are no hypoid gears in this transmission... hypoids are found only a right-angle final drive with the axes of the pinion and ring not intersecting (such as the ring and pinon in the rear axle of this Ranger pickup).



dcb said:


> Or are you saying they just drug the involute cutter in a straight line (on an angle to the axis of rotation, i.e. helix), instead of rotating the gear during the cut, and the teeth are deeper in the middle of the gear or something (how would that even work)? I mean we are talking about circles here, there's gonna be a curve somewhere. Did they not use an involute cutter?


Straight-cut teeth are still involute, they just don't spiral like a helical gear. If you cut a section through the gear on a plane perpendicular to the shaft axis, the involute tooth form looks the same whether the gear is straight-cut or helical.

But the TK4's gears (other than reverse) are almost certainly helical anyway...



dcb said:


> also, my own duh, straight cut are definitely louder when loaded, so hard to imagine a healthy straight cut idler making that much racket when the car is in second.


Agreed - the reverse is likely straight-cut, but that doesn't matter when it is just idling; straight-cut gears would only be a noise issue for the gear currently in use.


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## brian_ (Feb 7, 2017)

electro wrks said:


> We are getting somewhat OT here. terrorr, could you address the questions I asked in post 13. Maybe that will get us back on topic.


We're on-topic, in that we're sorting out what piotrsko introduced about "constant-mesh" and "straight-cut" gearing and their relationship to possible gear whine.

I agree that the whole straight-cut thing is likely irrelevant, and that alignment rather than gear whine is a potential issue.


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## brian_ (Feb 7, 2017)

electro wrks said:


> Name-wise the straight cut gears I'm thinking of are better known as spur gears.


Spur gears are just on parallel shafts - they can be straight-cut or helical. All of the gears in the transmission are spur gears.



electro wrks said:


> The angled teeth need to be in the form of a helix to mesh properly. If the teeth were near perfectly straight, and not in the form of a helix, they would only mesh on the very ends(corners) of the teeth. This would be extremely impractical and undesirable. And, not a design to use in a gearbox.


Actually they mesh just fine whether straight-cut or helical, because they have an involute tooth shape.

Again, unless they are damaged or a shaft is misaligned, the gears in the transmission are not going to be the source of an abnormal noise.


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## electro wrks (Mar 5, 2012)

brian_ said:


> Spur gears are just on parallel shafts - they can be straight-cut or helical. All of the gears in the transmission are spur gears


No, not according to W-pedia: https://en.wikipedia.org/wiki/Gear#Helical


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## dcb (Dec 5, 2009)

spur: 1.
a device with a small spike or a spiked wheel that is worn on a rider's heel and used for urging a horse forward.

If we are going to disregard the common vernacular, then even a hypoid pinion gear is a spur gear. But I think it has more to do with how it looks, i.e. from the side, and a helix gear just looks like a circle, not a spur. A straight cut gear looks like a spur, that jingle jangles. First recorded use in 1815-25

But it looks like the brits got confused somewhere, not knowing what cowboys were and whatnot, decided overthink it and make the term more general, instead of asking "hey, what do you mean by 'spur gear'?!?"

http://www.dictionary.com/browse/spur-gear

also worthy of note: http://www.ronsongears.com.au/a-brief-history-of-gears.php
"Various other patents followed until 1897 when Herman Pfauter of Germany invented the first hobbing machine capable of cutting both spur and helical gears."

more than you might want to know about the history of gears:
https://books.google.com/books?id=c...rman Pfauter helical gear patent 1897&f=false


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## electro wrks (Mar 5, 2012)

Makers and suppliers of spur and helical gears know the difference between the two: http://www.sdp-si.com/products/Gears/Index.php

Amazon does too: https://www.amazon.com/Mechanical-Gears/b?ie=UTF8&node=16412081

So does a venerable US company: http://www.bostongear.com/products/open-gearing/stock-gears

Here's an English company that seems to know the difference:http://www.gibbsgears.com/

Can we move on now to finding out what's really making this person's gearbox noisy?


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## brian_ (Feb 7, 2017)

dcb said:


> But it looks like the brits got confused somewhere, not knowing what cowboys were and whatnot, decided overthink it and make the term more general, instead of asking "hey, what do you mean by 'spur gear'?!?


Good catch.  Usage varies by country...
A British definition:


> a gear having involuted teeth either straight or helically cut on a cylindrical surface. Two such gears are used to transmit power between parallel shafts


Anyway, everyone agrees that spur gears rotate on parallel shafts, in contrast to bevel gears.

By the way, they had horses - and riders with spurs - in Britain before any Europeans settled in North America and eventually called themselves "cowboys". The word "spur" itself is apparently from Middle English...

Regardless of what "spur gear" means to anyone, the TK4 is presumably full of helical gears on parallel shafts, and so it shouldn't have excessive gear whine due to straight-cut gears.


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## brian_ (Feb 7, 2017)

piotrsko said:


> Oh I'm sorry, I just have one and have been inside it to rebuild it. I didn't google it to see how it works, I use the correct ford service manual. How obsolete.
> 
> The gears are cut on an angle, there is no helix curve to the cut. Hence my comment straight cut.


That is helical (each tooth is such a small fraction of a turn that it doesn't look curved). So... we're done with talk of gear whine due to straight-cut (or "spur") gears, right?


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## brian_ (Feb 7, 2017)

piotrsko said:


> ... I just have one and have been inside it to rebuild it...


It looks like the TK4 has a common design: a short input shaft has only one gear (to transfer drive to the countershaft), and only a single bearing in the transmission. This would mean that the pilot bearing is required to support the other end for proper gear alignment (not just to align the input shaft and crankshaft). Does this sound correct, from the hands-on perspective?

If the transmission depends on the pilot bearing this way, the kind of coupler or adapter alignment problem which was discussed earlier (post #13 by as electro wrks, as he has reminded us ) could cause gear noise despite perfectly good (until the misalignment destroys them) helical gears.


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## piotrsko (Dec 9, 2007)

I dunno perhaps google it?


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## dcb (Dec 5, 2009)

scan the service manual so we can


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## CFECO (Sep 15, 2015)

*Re: Max Transmission RPM? Will it blow?*

Have you done away with the rubber mounts on the tranny, and do you have rubber mounts on the motor? ANY, solid mounted powertrain component will make a lot of noise, even if it's in perfect order.


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## terrorr (Jul 17, 2017)

Thanks for all the input. Been gone awhile, had to take care of general life issues. The truck is parked for now and I will be working on it again in the spring. After I have more time to test and tinker I will get back with any findings.


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