TR690 Gearing Swap

[BruceyWV]

Anyone done it successfully? Or even the TR580? 

Would it be easier to just swap the entire transmission? If so I would think the TCU would be needed to make CANBUS happy? 

I've seen a couple 4EAT blow the front diff so I know they can be replaced independently so it should be possible in the TR580/690 since they're pretty similar on the front diff and AWD unit.

Looking to swap 4.11 to 4.44 gearing in my 2017 3.6 Outback. 

[heartless]

have no idea on the gearing swap, but if you do manage to do it, you will also need a matching rearend...

 

[BruceyWV]

9 hours ago, heartless said:

have no idea on the gearing swap, but if you do manage to do it, you will also need a matching rearend...

 

Of course. (:

I already have the rear end from an Ascent but that seems like a simple process. Similar to when I swapped the rear end to match the H6 I put in the Baja. 

I'm yet to get the parts for the front diff because if just swapping the entire transmission seems easier I might just go that route. 

[heartless]

in all honesty, i would think just swapping trannies would be about the easiest route.. no matter which direction you go, you are gonna have to pull the whole works anyway.

and glad you know about changing rear ends... there are a whole lot of folks that dont know that.

[GeneralDisorder]

Unlikely that the existing transmission control would be happy with a gear ratio change, and even more unlikely that the car would be happy with a different transmission controller from another model. 

GD

[BruceyWV]

6 hours ago, GeneralDisorder said:

Unlikely that the existing transmission control would be happy with a gear ratio change, and even more unlikely that the car would be happy with a different transmission controller from another model. 

GD

 

11 hours ago, heartless said:

in all honesty, i would think just swapping trannies would be about the easiest route.. no matter which direction you go, you are gonna have to pull the whole works anyway.

and glad you know about changing rear ends... there are a whole lot of folks that dont know that.

If its that easy I would love it but I kinda doubt it with the CANBUS cars. The ratios are different in addition to the Ascent having 8 'gears' while the 3.6 Outback only has 6.

I know when someone swaps in a Tribeca transmission for better gearing into an H6 Outback they need the TCU for it to be happy and those are CANBUS. 

Hence me thinking the easiest way to get 4.44 gearing would be to simply swap the front diff ratio. The computers would never know the difference. 

 

[GeneralDisorder]

1 hour ago, BruceyWV said:

 

If its that easy I would love it but I kinda doubt it with the CANBUS cars. The ratios are different in addition to the Ascent having 8 'gears' while the 3.6 Outback only has 6.

I know when someone swaps in a Tribeca transmission for better gearing into an H6 Outback they need the TCU for it to be happy and those are CANBUS. 

Hence me thinking the easiest way to get 4.44 gearing would be to simply swap the front diff ratio. The computers would never know the difference. 

 

The computer absolutely WILL know the difference. The computer has access to the vehicle speed on the CANBUS and it internally knows it's own shaft speeds, input speeds, and output speeds. Vehicle speed will no longer correlate as expected with engine RPM, and with the CVT the transmission computer is designed to keep the engine in a specific RPM band and to use changes in the gearing for differences in road speed. 

I would say it's unlikely that the computer will accept a change in gearing without throwing some codes at the very least. Since it's effectively impossible to know the programming of the TCU as this is proprietary closed source software the only way to know for sure would be to try it. Buy I would guess it probably won't work. 

GD 

[el_freddo]

6 hours ago, GeneralDisorder said:

I would say it's unlikely that the computer will accept a change in gearing without throwing some codes at the very least. Since it's effectively impossible to know the programming of the TCU as this is proprietary closed source software the only way to know for sure would be to try it. Buy I would guess it probably won't work. 

Agreed. Only one way to find out... 

If it throws a code due to the different shaft rotational speeds than expected you could try making custom tone rings for the ABS system assuming these are the speed sensor pick ups for Canbus system.

Cheers 

Bennie

[GeneralDisorder]

9 hours ago, el_freddo said:

Agreed. Only one way to find out... 

If it throws a code due to the different shaft rotational speeds than expected you could try making custom tone rings for the ABS system assuming these are the speed sensor pick ups for Canbus system.

Cheers 

Bennie

The tone rings for the ABS are integrated into the sealed bearing assembly. They are not accessible. So you would have to design new external tone rings and sensors to match or disassemble and redesign the tone ring setup inside the sealed bearing/hub assembly. This would then result in the car reporting a different road speed to EVERY computer including the gauge cluster. While this would probably work to fool the computers - it would be less than desirable in other ways. 

At the end of the day - the slight change in gearing isn't worth it and in any case it's a CVT automatic with a torque converter so you don't even need the gearing. You have all the gearing you need for wheeling (as much as a Subaru with 10" or less under it's oil pan can wheel) because you have a TC. If you want to do serious wheeling go find something with a solid axle and appropriate clearance - my K5 Jimmy has 23" under the oil pan for example. 

GD

[BruceyWV]

1 hour ago, GeneralDisorder said:

The tone rings for the ABS are integrated into the sealed bearing assembly. They are not accessible. So you would have to design new external tone rings and sensors to match or disassemble and redesign the tone ring setup inside the sealed bearing/hub assembly. This would then result in the car reporting a different road speed to EVERY computer including the gauge cluster. While this would probably work to fool the computers - it would be less than desirable in other ways. 

At the end of the day - the slight change in gearing isn't worth it and in any case it's a CVT automatic with a torque converter so you don't even need the gearing. You have all the gearing you need for wheeling (as much as a Subaru with 10" or less under it's oil pan can wheel) because you have a TC. If you want to do serious wheeling go find something with a solid axle and appropriate clearance - my K5 Jimmy has 23" under the oil pan for example. 

GD

The wife has a '21 Bronco 2 door Sasquatch on order.

I'm sure it's a better wheeler than the Subaru too. 

That's not why I'm doing it. I am doing it to say I did it.

Similar to the VTD center swap for the '17 3.6 I'm also researching.

Edited July 14, 2021 by BruceyWV

[GeneralDisorder]

8 hours ago, BruceyWV said:

The wife has a '21 Bronco 2 door Sasquatch on order.

I'm sure it's a better wheeler than the Subaru too. 

That's not why I'm doing it. I am doing it to say I did it.

Similar to the VTD center swap for the '17 3.6 I'm also researching.

Uh huh. Manufacturers are intent on not allowing you to do this sort of thing. You are fighting an uphill battle against a determined, and economically superior foe. Why? It's just a waste of time and effort. Go put your effort into something that's not just competing against the marketing and engineering departments of a corporation structured to take your money every 3-5 years when the lease is up. 

Ford eh? Not a fan myself. They do trucks and that's their thing but hopefully it's not another Focus RS or six point uh-oh! 

None of the cars manufactured in the last ~15 years are designed to be repaired or modified. In fact they are designed specifically to thwart any such efforts. Manufactures only make money when you throw away old products and purchase new ones. 

Regardless of your intent - I still say it's very unlikely to work the way you hope. I've listed several technical reasons why it's unlikely to work and there are probably a dozen more that I'm not considering since I've not had any of these transmissions apart for measurement and documentation. 

GD

[BruceyWV]

9 hours ago, GeneralDisorder said:

Uh huh. Manufacturers are intent on not allowing you to do this sort of thing. You are fighting an uphill battle against a determined, and economically superior foe. Why? It's just a waste of time and effort. Go put your effort into something that's not just competing against the marketing and engineering departments of a corporation structured to take your money every 3-5 years when the lease is up. 

Ford eh? Not a fan myself. They do trucks and that's their thing but hopefully it's not another Focus RS or six point uh-oh! 

None of the cars manufactured in the last ~15 years are designed to be repaired or modified. In fact they are designed specifically to thwart any such efforts. Manufactures only make money when you throw away old products and purchase new ones. 

Regardless of your intent - I still say it's very unlikely to work the way you hope. I've listed several technical reasons why it's unlikely to work and there are probably a dozen more that I'm not considering since I've not had any of these transmissions apart for measurement and documentation. 

GD

Eh. It's her car and something she's excited for. It was time to get rid of the H6 VDC Baja anyway. Plus the 2.7 Eco boost seems to have good ratings. 

It's not like GM is offering anything competitive in that sector anyway. Current Blazers are a joke. I still have my 99 3/4 Ton Suburban and '06 1/2 Ton Suburban as well. 

What can I say? I like cars. 

[el_freddo]

2 hours ago, BruceyWV said:

What can I say? I like cars. 

I hear you on that one! Four regos and insurances... love driving them so that’s that.

Cheers 

Bennie

[GeneralDisorder]

7 hours ago, BruceyWV said:

Eh. It's her car and something she's excited for. It was time to get rid of the H6 VDC Baja anyway. Plus the 2.7 Eco boost seems to have good ratings. 

It's not like GM is offering anything competitive in that sector anyway. Current Blazers are a joke. I still have my 99 3/4 Ton Suburban and '06 1/2 Ton Suburban as well. 

What can I say? I like cars. 

No - I wouldn't buy anything from GM either. But then I just won't buy new cars period. You take a bath on them in depreciation and they are designed with a planned lifespan of the lease period. I could buy any new car I want, pay cash for it, and write it off as a shop expense. Unfortunately there's just nothing out there that isn't a pile of proprietary intellectual property wrapped in plastic and bits of shiny. No thanks. 

I like cars too - one's I can actually modify without reverse engineering a dozen computers designed by teams of engineers with a specific mandate to make that process nigh impossible. I don't need that frustration and they can keep their overly engineered and under designed plastic crap. 

GD

[heartless]

On 7/15/2021 at 2:45 PM, GeneralDisorder said:

I like cars too - one's I can actually modify without reverse engineering a dozen computers designed by teams of engineers with a specific mandate to make that process nigh impossible. I don't need that frustration and they can keep their overly engineered and under designed plastic crap. 

AMEN! to that!

 

[BruceyWV]

So since this thread I have swapped a 2008 CANBUS 5EAT 3.0 Outback final drive ratio. 

I've also recently successfully swapped a 2013 Outback TR580 from 3.9 to 4.11 final drive without issue. 

Planning out the 3.6 TR690 now and using the previous two as proof of concept for it. 

I have a write up on the recent TR580 swap if anyone is interested. 

https://www.subaruoutback.org/threads/diy-outback-wilderness-or-cheaper-cvt-repair.564652/

 

Hope this helps! 

[idosubaru]

20 hours ago, BruceyWV said:

So since this thread I have swapped a 2008 CANBUS 5EAT 3.0 Outback final drive ratio. 

I've also recently successfully swapped a 2013 Outback TR580 from 3.9 to 4.11 final drive without issue. 

Planning out the 3.6 TR690 now and using the previous two as proof of concept for it. 

I have a write up on the recent TR580 swap if anyone is interested. 

https://www.subaruoutback.org/threads/diy-outback-wilderness-or-cheaper-cvt-repair.564652/

 

Hope this helps! 

Nice work Brucey.  That's cool trying things. Keep it up. The guys at Hartsells on University got a kick out of inspecting the legacy I converted to FWD automatic just to do it.  You did the hard work but hindsight being 20/20 It seems risky to have an unforgiving data point downstream of the final drive output.

I've got a 14 Forester parts car I was wondering if I could swap the trans into an outback....looks like it would work on what you're doing.   

I ran into a police officer at the local highschool a week or two ago and he said "Dude I saw an XT6 just like yours, look at this picture".....it was mine.  Lol.

Edited March 5 by idosubaru