Inboard vs outboard driven CVT

[Wyatt]

Hey everyone,

I had a quick question. What's the difference between an inboard and outboard driven unit? I bought a 20 series Max Torque driven unit. It was labeled outboard but they said please specify inboard in order notes, which I did.

I believe my setup is inboard as the spring/cam faces the engine.

The reason I ask is, I'm seeing quite a bit of what I assume to be belt debris/particals from my brand new belt. Perhaps that's normal break in wear? The belt is just mildly warm to the touch post ride. The belt alignment is as good as I can possibly tell.

Thanks!

 

[anickode]

The difference is the direction the spring is wound. If installed backwards, it will not function properly, which can result in rapid belt wear.

 

[Wyatt]

The difference is the direction the spring is wound. If installed backwards, it will not function properly, which can result in rapid belt wear.

Okay thanks! It still moves with rpm. The cam is on the right side of the buttons like my old one so I think it's correct?!

 

[65ShelbyClone]

Photo(s)?

 

[Wyatt]

Photo(s)?

What can I show you?

Edit: I figured it out, as previously mentioned it is setup for an outboard mount even though I requested inboard. Thanks guys!

 

[WrenchnIsWhatIdo]

sorry if I'm adding to confoosh-ion.

I thought the inboard vs outboard
ment what side had the flat edge in it.?
Inboard =Flat side towards the engine......W

 

[anickode]

sorry if I'm adding to confoosh-ion.

I thought the inboard vs outboard
ment what side had the flat edge in it.?
Inboard =Flat side towards the engine......W

No flat edge on a 20 series (and the "flat edge" on a 30 series is actually still angled about 2°)

An asymmetrical torque converter (the kind with one almost-flat edge) like the 30 series is asymmetrical to allow it to run outboard without alignment problems in high gear.

A symmetrical torque converter (like a 20 or 40 series with 2 angled edges) is INTENDED to be run with the driven inboard so the belt stays aligned as the ratio changes. They CAN be run outboard at the expense of belt alignment (and therefore belt life) with a reverse-wound spring. But this should be avoided whenever possible.

 

[itsid]

I bought a 20 series Max Torque driven unit. It was labeled outboard but they said please specify inboard in order notes, which I did.
..

There's already a problem with this..
the Max Torque TC and the Comet series 20 ARE NOT COMPATIBLE!
So either you need a Max Torque or a series 20.. and while they look alike you can only have one.

Comet series 20 has a 15° slope angle on their sheaves (30° combined face angle)
while the Max torque only has a 13° angle (26° combined)

And that means the belt isn't fully engaged if you run the wrong belt.
(either wrong for the driver, or the driven if those two don't match)

So yeah.. we still need pics:
All of the TC: driver, driven and belt.
Driven pics help if we see spring and cam

...
A symmetrical torque converter (like a 20 or 40 series with 2 angled edges) is INTENDED to be run with the driven inboard so the belt stays aligned as the ratio changes. They CAN be run outboard at the expense of belt alignment (and therefore belt life) with a reverse-wound spring. But this should be avoided whenever possible.

That's partly true even for comet series TCs..
the MaxTorque is INTENDED to run outboard (while still being a symmetrical TC)
the driven must be allowed to float on the jackshaft to properly self align with the belt though.
(which the MaxTorque does!) that way it's as reliable as an inboard mounted clutch and the belt will never know the difference
and that holds true for the series 20 and 40 comets as well.
the driven must be allowed to float (one belt width at least IIRC)
that's the reason I seriously dislike the GoPowerSports back plate series 40 ..
no float for the driven... big money.. ruined belt in short order


'sid

 

[anickode]

I completely grazed over the max torque bit.

 

[Wyatt]

There's already a problem with this..
the Max Torque TC and the Comet series 20 ARE NOT COMPATIBLE!
So either you need a Max Torque or a series 20.. and while they look alike you can only have one.

Comet series 20 has a 15° slope angle on their sheaves (30° combined face angle)
while the Max torque only has a 13° angle (26° combined)

And that means the belt isn't fully engaged if you run the wrong belt.
(either wrong for the driver, or the driven if those two don't match)

So yeah.. we still need pics:
All of the TC: driver, driven and belt.
Driven pics help if we see spring and cam


That's partly true even for comet series TCs..
the MaxTorque is INTENDED to run outboard (while still being a symmetrical TC)
the driven must be allowed to float on the jackshaft to properly self align with the belt though.
(which the MaxTorque does!) that way it's as reliable as an inboard mounted clutch and the belt will never know the difference
and that holds true for the series 20 and 40 comets as well.
the driven must be allowed to float (one belt width at least IIRC)
that's the reason I seriously dislike the GoPowerSports back plate series 40 ..
no float for the driven... big money.. ruined belt in short order


'sid

Ah, that could be it!

I went back and checked the product page, it says it has an 18 degree face for a total of 36, perhaps that's close enough to get away with, with it setup as inboard?

I'm going to try it, if the belt blows up I'll just go and get a new driven unit, again... oops.

 

[Wyatt]

Update: I contacted Gopowersports and they told me the Max Torque unit they sell is a direct replacement for the comet 20 series unit?

I'm seeing fine little bits of debris but the belt is ambient temperature. Perhaps that's just normal then.

I'm a noob here, just trying to learn! I'll get some pics.

 

[itsid]

Ah, that could be it!

I went back and checked the product page, it says it has an 18 degree face for a total of 36, perhaps that's close enough to get away with, with it setup as inboard?

I'm going to try it, if the belt blows up I'll just go and get a new driven unit, again... oops.

That's INCORRECT it has a 13° angle:
maybe GPS misread the specs? (the three mistaken for an eight thanks to lousy OCR or something?)
Who said it's 13° you might ask...
http://maxtorque.com/converters.php
THEM!

Update: I contacted Gopowersports and they told me the Max Torque unit they sell is a direct replacement for the comet 20 series unit?

I'm seeing fine little bits of debris but the belt is ambient temperature. Perhaps that's just normal then.

I'm a noob here, just trying to learn! I'll get some pics.

That too unfortunately is INCORRECT, according to Maxtorque the parts are NON-INTERCHANGEABLE.

it's NOT a direct replacement it simply doesn't match the belt angle, not even closely.
Yes it will move the driven (with a comet belt)
BUT at a significant loss of power ;
a TC has (thanks to slippage) already a really bad power transfer ratio (at best 80% for modern high tech Belt CVTs..)
a series 20 is certainly not high tech and surely not exactly modern.
but let's assume you have a 80% power transfer
(likely more in the realms of 70% but alright)

You now reduced the contacting surface of the belt and driven sheave by ~50% and you lost at least that in power transfer ratio as well (to additional slip)
soo 40% of the engine power reaches the driven pulleys sprocket..

About'ish and estimated.. maybe a bit better, but likely a bit worse ...


You think that's agood choice?
I don't.

get a series 20 driven (mfgsupply.com has them)
and ask GPS for a refund.. since the MaxTorque is surely not working in your favour.

'sid

 

[Wyatt]

That's INCORRECT it has a 13° angle:
maybe GPS misread the specs? (the three mistaken for an eight thanks to lousy OCR or something?)
Who said it's 13° you might ask...
http://maxtorque.com/converters.php
THEM!



That too unfortunately is INCORRECT, according to Maxtorque the parts are NON-INTERCHANGEABLE.

it's NOT a direct replacement it simply doesn't match the belt angle, not even closely.
Yes it will move the driven (with a comet belt)
BUT at a significant loss of power ;
a TC has (thanks to slippage) already a really bad power transfer ratio (at best 80% for modern high tech Belt CVTs..)
a series 20 is certainly not high tech and surely not exactly modern.
but let's assume you have a 80% power transfer
(likely more in the realms of 70% but alright)

You now reduced the contacting surface of the belt and driven sheave by ~50% and you lost at least that in power transfer ratio as well (to additional slip)
soo 40% of the engine power reaches the driven pulleys sprocket..

About'ish and estimated.. maybe a bit better, but likely a bit worse ...


You think that's agood choice?
I don't.

get a series 20 driven (mfgsupply.com has them)
and ask GPS for a refund.. since the MaxTorque is surely not working in your favour.

'sid

https://www.gopowersports.com/driven-3-4-bore-7-dia-after-market-max-torque-outboard-20602/

There's the listing, so it isn't actually a Max Torque, it's probably some knock off of a Max Torque.

 

[Wyatt]

That's INCORRECT it has a 13° angle:
maybe GPS misread the specs? (the three mistaken for an eight thanks to lousy OCR or something?)
Who said it's 13° you might ask...
http://maxtorque.com/converters.php
THEM!



That too unfortunately is INCORRECT, according to Maxtorque the parts are NON-INTERCHANGEABLE.

it's NOT a direct replacement it simply doesn't match the belt angle, not even closely.
Yes it will move the driven (with a comet belt)
BUT at a significant loss of power ;
a TC has (thanks to slippage) already a really bad power transfer ratio (at best 80% for modern high tech Belt CVTs..)
a series 20 is certainly not high tech and surely not exactly modern.
but let's assume you have a 80% power transfer
(likely more in the realms of 70% but alright)

You now reduced the contacting surface of the belt and driven sheave by ~50% and you lost at least that in power transfer ratio as well (to additional slip)
soo 40% of the engine power reaches the driven pulleys sprocket..

About'ish and estimated.. maybe a bit better, but likely a bit worse ...


You think that's agood choice?
I don't.

get a series 20 driven (mfgsupply.com has them)
and ask GPS for a refund.. since the MaxTorque is surely not working in your favour.

'sid

I recently discovered both of my components are Max Torque units.

The thing that confuses me is that the only Max Torque belts I can find are 15 degrees, yet Max Torque's website says they are 13 degree clutches?!

 

[itsid]

would you mind to measure the OD of the driven for me?

this sounds too weird for me atm and I need to get some of the confusion out of my head.
I know no three button clones (well series 40 but that's a differnt style button altogether)

Also I know no maxtorque reverse spring..
and for all I know maxtorque TC run outboard
(not sure the spring is identical to a comet series 20.. chances are it is, but I don't know)

The drivers are indistinguishable from one another (unless you find a comet or maxtorque stamp )

But what's fair to assume is, that if you buy an original MaxTorque belt,
you will have the correct sheave angle (for the driven at least)..
if it's 13,15 or 18° labelled doesn't matter much.. that could always be a typo on the website.
(especially 3 5 and 8 are prone for false OCR results)

I'll see if I can dig some infos up..

'sid

 

[Wyatt]

would you mind to measure the OD of the driven for me?

this sounds too weird for me atm and I need to get some of the confusion out of my head.
I know no three button clones (well series 40 but that's a differnt style button altogether)

Also I know no maxtorque reverse spring..
and for all I know maxtorque TC run outboard
(not sure the spring is identical to a comet series 20.. chances are it is, but I don't know)

The drivers are indistinguishable from one another (unless you find a comet or maxtorque stamp )

But what's fair to assume is, that if you buy an original MaxTorque belt,
you will have the correct sheave angle (for the driven at least)..
if it's 13,15 or 18° labelled doesn't matter much.. that could always be a typo on the website.
(especially 3 5 and 8 are prone for false OCR results)

I'll see if I can dig some infos up..

'sid

Thanks Sid! I measured the angles as best I could and they both come out to 13 degrees for me on the driver and driven. OD of the driven is 7 inches.

 

[itsid]

thank you
yes that indeed sounds very much like everything is indeed a maxtorque TC, no comet parts yet

Well then, I asked Jim Donovan if there is a Maxtorque reverse wound spring
(that would allow the driven to run inboard)
and he verified that there are indeed.
(since for customers convenients sake they make both outboard and inboard setups)

Judging by how your cam rests against the buttons, it's setup as inboard driven;
and even the spring appears to be correct
(it should tighten if you move the cam away from the button, not open up)

So far everything seems to be well and good!

I'm sure he doesn't mind if I partly quote his email..

When our unit is mounted OUTBOARD the driven unit must float on the jackshaft so it can self-align with the driver unit on the engine. The Driver unit needs about 3/8” inward float to self-align.

The better approach is to just buy and INBOARD DRIVEN unit and then the DRIVER and DRIVEN work in unison. Our belts are the same as Comet’s series 20. They are symmetrical and they are both 13 degrees per side or a total combined angle of 26 degrees. (Comet’s and Max-Torque are the same in the series 20.) If anyone has 15 degrees it is a misprint which Comet was famous for not proofreading their catalogue.

And with that I'm reasonably confident to call your setup good
inboard driven (and correctly set up) and if you got a correct belt for your center to center distance (as it appears to be judging by it's tension),
you will be fine as you are!

And as a bonus, according to Jim, as you can see the belts are in fact identical to Comet belts (and thus the TC sheaves are as well which makes it interchangeable.. even IF the driver is a Comet and the driven a MaxTorque)

So yeah.. all good!

'sid

PS Special Thanks to Jim Donovan from MaxTorque,
who was kind enough to answer all my questions via email!

 

[Wyatt]

thank you
yes that indeed sounds very much like everything is indeed a maxtorque TC, no comet parts yet

Well then, I asked Jim Donovan if there is a Maxtorque reverse wound spring
(that would allow the driven to run inboard)
and he verified that there are indeed.
(since for customers convenients sake they make both outboard and inboard setups)

Judging by how your cam rests against the buttons, it's setup as inboard driven;
and even the spring appears to be correct
(it should tighten if you move the cam away from the button, not open up)

So far everything seems to be well and good!

I'm sure he doesn't mind if I partly quote his email..



And with that I'm reasonably confident to call your setup good
inboard driven (and correctly set up) and if you got a correct belt for your center to center distance (as it appears to be judging by it's tension),
you will be fine as you are!

And as a bonus, according to Jim, as you can see the belts are in fact identical to Comet belts (and thus the TC sheaves are as well which makes it interchangeable.. even IF the driver is a Comet and the driven a MaxTorque)

So yeah.. all good!

'sid

PS Special Thanks to Jim Donovan from MaxTorque,
who was kind enough to answer all my questions via email!

Wow thanks Sid that's awesome! You're an absolute legend! Much appreciated!!!! Thanks to Jim too!

GoPowerSports even relisted their Maxtorque driven unit as 13 degrees on the product page when I talked to them. All is right with the world!

 

[itsid]

Thanks, but I'm just trying to help ...

Glad GPS fixed the description.
even gladder I was incorrect about the series 20 and the MaxTorque being incompatible,
not them.



'sid