6MT Master Swap Thread

Ive been in and out of this thread over the years, but cant say ive read all of these pages, so if this has been covered, I apologize, but I believe I may have another potential solution for more easy to obtain rear axles when converting to the R180.

 

 

 

I think you are able to run STi axles (2004-2007) when installing a R180 differential in the 4th gen legacy platform if you swap to 2012+ impreza rear hubs.

 

 

 

As far as I could tell, the STi axles are nearly the same length as the Spec B axles based on this thread reply: https://legacygt.com/forums/showpost.php?p=4392808&postcount=17

 

 

 

And this image for replacement STi axles (which are less than $60 )

 

 

 

 

 

Next, the hubs gotta be a match aside from the drive spline, the new ones have to have 27 splines where our stock hubs have 25.

 

 

 

2012-2019 (maybe later) Impreza (and everything else on that platform that came later : https://www.rockauto.com/en/moreinfo.php?pk=5829054

 

 

 

2005-2009 Legacy Rear Hubs: https://www.rockauto.com/en/moreinfo.php?pk=1119780

 

 

 

The key differences here (aside from the spline count) is the flange offset which differs by about 1mm and the height of the bearing in the back. More on that below:

 

 

 

The 'new' hubs would push the rotor out about 1mm. This may cause some issues with both the parking brake and rear brake. I think this 1mm may be forgivable when working with new rotors and slightly worn brake pads. Who knows, it might even work with new pads on the caliper, but youd give yourself more room with slightly worn pads.

 

 

 

Secondly, that hub sticks into the trailing arm a little bit more. This poses 2 problems: axle length (which is kinda a question mark to begin with) and abs sensor. After looking at the Legacy trailing arms, you might be able to get away with drilling out the threaded hole for the screw that holds the ABS sensor in and holding the sensor in some other way.

 

 

 

Hopefully you are still with me, but I just wanted to share what I found when considering my options while looking at a potential 6MT swap. The spec B axles seemed a bit difficult to come by so I started looking at adapting the car to use more common axles. I havent tried it yet but I have enough parts laying around to try it off the car should I decide to go down this path.

 

 

 

I personally have the option of machining alot of this stuff to work, but I like to put the effort up front to try to find solutions that dont require machining of common replacement items, especially so others can employ the same solutions.

I was researching this in a separate thread. One member has done it machining the trailing arm to accept the STI hub. This is something I'm looking into currently though with possibly pressing half the wheel hub of the mounting side of the legacy onto the STI hub. Front requires switching knuckles unless something similar with the hub is done, I have questions of length concerns in the front though if the knuckle isn't swapped. I'm currently trying to do this to a spec b drivetrain for the better hubs. CVJ axles is local to me in Denver here and they will do custom axles, also they are reputable for their OEM Subaru axle rebuilds which they keep in stock. They mostly do Toyota off-road custom stuff but they will build you something if you want. I think I may go custom if I have to axle wise, and may anyway for strength if I don't want to pay group n STI axle pricetag. Edited August 11, 2020 by SpecDubC

I saw the other thread and I had hoped when looking into this there was a silver bullet solution for people wanting both either keep 5x100 when swapping, or easily swap to 5x114.3. I found no such missing link part in my search.

 

When I did my research, it seemed Subaru employs 2 of what I will call 'bolt patterns' on rear hubs for the vehicles designed as a derivative of the BP/BL chassis and beyond. There is the small bolt pattern that we have and the larger bolt pattern that the STis use.

 

I found no example of a 5x114.3 using the small bolt pattern (which is why machining the trailing arm to fit these hubs seems like a decent choice), but I did in fact see some cars with 5x100 employing a 'large bolt pattern' rear hub, suggesting that for those cars there could be a parts bin upgrade to 5x114.3. The next generation legacy (BM/BR) is one of these cars. I didnt really look into that though.

 

I have some spare front hubs off my car laying around and I could try pressing the inner part out, but that doesnt really help me too much about the rear, other than feasibility in being able to disassemble the preassembled hub/bearing units.

 

A few more thoughts on hubs: Given the hub housing fits in the same bore between STi hub and the 'smaller' hubs we have, I would think the only way to increase longevity of the bearings would be to increase the width of hub (using wider rollers inside the bearing) which actually appears to have been done with the newer impreza hub I suggested. I wonder if these hubs have about the same resistance to wear the STi hubs do.

 

That being said, my rear hubs have 80k mi on them and if they started making noise tomorrow, I wouldnt exactly be upset with that lifespan, so while I can understand seeking greater strength components, my personal use hasn't driven me down a path to seek to increase the strength on that component, especially when they arent that hard to change.

 

I have spare trailing arms to mess around with and a machine shop to play in...but I havent yet seen a reason to set the trailing arm up to drill it out for the large bolt pattern hub.

Hi guys,

 

Awesome info in this thread so far, though maybe too much for me to remember at the time of this post!

 

I have a 2008 spec b, h6, 5eat wagon (aussie version) which I am going to attempt to convert to a 6mt. I am 100% fine with all mechincal aspects (including ABS unit swap) and lengthening the gearbox crossmember etc. I'm only interested in your thoughts on the wiring and what I have found from looking over wiring diagrams so far.

 

I know the manual map/ecu program can be loaded into the auto ecu system but am not confident in being able to do that at this stage.

 

I have the ecu, cluster, BIU all from a doner car which the gearbox came from, what I am hoping to do is swap these into the auto wagon, take out the TCU and add/remove a few wires for the clutch etc (putting it simply haha).

 

Things that I have noted are:

Engine ECU wiring:

- Remove TCU and inhibitor relay. Bridge the switching wire on the inhibitor relay plug.

- Wire in the neutral safety switch to C31 on the ECU - check that this wire connects to the joint connector which also connects to the cruise control switch and C6 on ecu

- Add clutch switch to C25 on ecu - this wire should already exist on the auto loom

- all other ecu inputs look identical between auto and manual cars

 

Starter System:

- Disconnect any wire going into C31 on the manual ecu

- All ECU pins and wires look the same between auto and manual

 

Back-up lighting:

- Remove auto back-up light relay - possibly connect the 6mt back up light switch to these wires.

 

CANBUS system:

- unknown if any errors will be thrown provided the above are wired correctly and TCU is missing

 

Body Integrated unit:

- Swap over the key barrel from the donor car, will then use keys from that car, swap over the key barrel in door to suit.

- unknown yet if anything else needs to be done other than swapping the doner BUI into the wagon.

 

Grounds:

- pay close attention to all of these, make sure I'm not missing any!

 

Interested in your thoughts and if anyone has actually done the conversion this way. Cheers!

Edited October 15, 2020 by crjohnson

Hi everyone I'm looking into buying a wrecked sti donor car. I'm just wondering what's the best year STI to 6 speed transmission swap into our cars? My car is already a 5 speed but since I'm building my engine currently I'm starting to consider this swap. I see so many options but I think if I got a donor car I can part out most of it.

Hi everyone I'm looking into buying a wrecked sti donor car. I'm just wondering what's the best year STI to 6 speed transmission swap into our cars? My car is already a 5 speed but since I'm building my engine currently I'm starting to consider this swap. I see so many options but I think if I got a donor car I can part out most of it.

 

08+ sti, unless you can find an 07 jdm forester sti

08+ sti, unless you can find an 07 jdm forester sti

 

I keep getting mixed reviews some say the 06-07 sti's are the best and others say 08+ sti. If I run the 08 sti rear diff. I'll need spec b rear axles correct and an LGT auto driveshaft correct?

06-07 jdm forester sti is the holy grail of 6mt

you can always buy a custom 6mt from ZF Design (on facebook) and get exactly what you want.

06-07 jdm forester sti is the holy grail of 6mt

you can always buy a custom 6mt from ZF Design (on facebook) and get exactly what you want.

 

Why is that the best?

It has an A.P. Suretrac front diff compared to the open diff in the Spec B's. Everything else is the same. In short, the suretrac diff has the ability to detect and send torque to wheel with the most traction.

 

Some good reading here if you want to know more.

https://www.iwsti.com/threads/suretrac-differential-what-does-it-mean-to-sti-owners-long.1420/

Im picking up the following and just looking for some reassurance that I dont need the driveshaft, any of the axles, crossmember (minus bushing).

Seller had offered the hubs as well, but again just reassure me that I dont need them.

2005 sti 6spd swap.

 

What’s included:

Trans

Rear diff

Axles

Driveshaft

Crossmember

Slave cylinder

Stock clutch(recently was replaced)

You cannot use the hubs, driveshaft or axles in your set-up. You'll need to source Legacy units for those; spec. B rear halfshafts and a 4 speed auto driveshaft. You can re-use your existing transmission crossmember.

Hey guys, anybody have any thoughts on this? I've also found that the BIU should go straight into the wagon without any issues.

 

Hi guys,

 

Awesome info in this thread so far, though maybe too much for me to remember at the time of this post!

 

I have a 2008 spec b, h6, 5eat wagon (aussie version) which I am going to attempt to convert to a 6mt. I am 100% fine with all mechincal aspects (including ABS unit swap) and lengthening the gearbox crossmember etc. I'm only interested in your thoughts on the wiring and what I have found from looking over wiring diagrams so far.

 

I know the manual map/ecu program can be loaded into the auto ecu system but am not confident in being able to do that at this stage.

 

I have the ecu, cluster, BIU all from a doner car which the gearbox came from, what I am hoping to do is swap these into the auto wagon, take out the TCU and add/remove a few wires for the clutch etc (putting it simply haha).

 

Things that I have noted are:

Engine ECU wiring:

- Remove TCU and inhibitor relay. Bridge the switching wire on the inhibitor relay plug.

- Wire in the neutral safety switch to C31 on the ECU - check that this wire connects to the joint connector which also connects to the cruise control switch and C6 on ecu

- Add clutch switch to C25 on ecu - this wire should already exist on the auto loom

- all other ecu inputs look identical between auto and manual cars

 

Starter System:

- Disconnect any wire going into C31 on the manual ecu

- All ECU pins and wires look the same between auto and manual

 

Back-up lighting:

- Remove auto back-up light relay - possibly connect the 6mt back up light switch to these wires.

 

CANBUS system:

- unknown if any errors will be thrown provided the above are wired correctly and TCU is missing

 

Body Integrated unit:

- Swap over the key barrel from the donor car, will then use keys from that car, swap over the key barrel in door to suit.

- unknown yet if anything else needs to be done other than swapping the doner BUI into the wagon.

 

Grounds:

- pay close attention to all of these, make sure I'm not missing any!

 

Interested in your thoughts and if anyone has actually done the conversion this way. Cheers!

Hey guys well I went ahead and did the conversion, all is good and running perfect. This was an Aussie MY08, spec B, h6 wagon, 5eat to 6mt conversion.

 

No harness swap, I feel like this was far less work than pulling the entire dash and HVAC system out!

 

 

Here are my notes on the wiring:

 

 

 

- get an accurate copy of the FSM for your car!

 

 

 

- Bypass the inhibitor relay shown in ST(06)-01. I made small wire approx. 50mm long with 2 male, flat blade terminals on each end. Plugged it into poles 3 and 4. Leave the other terminals in the relay plug empty. Cover with electrical tape. The relay is located up behind the fuse box to the right of the steering wheel.

 

 

 

- I ran 2 x 2core wires from the gearbox, through the firewall and to the ecu (neutral safety switch) and to the back-up light relay.

 

 

 

- Wire in the back-up/reverse light as per BACK/L(R )-01 in the FSM. The reverse wires only need 2 male flat blade terminals and to be plugged into poles 3 and 4 on the relay plug. Leave the other terminals in the relay plug empty. Cover with electrical tape

 

 

 

- Wire in the neutral safety switch to C31 on the ECU (see page E/G(RH6)-12 in FSM). I cut the existing C31 wire, joined the NSS to the ECU side of that wire, then joined the other NSS wire to the B122 joint connector. I spliced into 1 wire in that joint connector and joined the NSS wire to that. The other end of the C31 wire that you cut just gets taped up.

 

 

 

- Wire in the clutch as per E/G(RH6)-05. I ran a 2 core wire from the clutch pedal/switch across to the ECU, then cut the C25 wire (which exists in the auto loom), joined clutch wires to that.

 

 

 

- Add a pin and wire to C15 on the ECU and ground this to the chassis. This is the auto/manual ID wire for the ECU. The diagrams I had showed this joining with C14 which I originally did but this caused a bunch of "circuit high" faults which all pointed to a short circuit somewhere. Ground this to the chassis or ECU mounts as I did.

 

 

 

- Remove the PV-IGN relay, I don't really know what this does, looks like some sort of power supply to the TCM.

 

 

 

Plug in your BUI, cluster, ECU, Key barrel assembly for the manual version. To remove the key barrel, use a sharp cold-chisel and gently hammer the security bolts off (in clockwise direction), replace with M8 screws. Unplug the TCM (hide those plugs somewhere up in the dash), tape up the 2 x auto trans plugs in the engine bay (you only need the oxy sensors plugs). Off you go!

 

 

 

I also used a 21200AA072 thermostat, these open and are fully open 4degrees lower than the standard h6 thermostat. I can definitely see lower temps on the BTSSM gauges. See the link below for more info:

 

 

 

https://legacygt.com...postcount=14760

Edited January 11, 2021 by crjohnson

good job mate!

What would you all expect to pay a shop to swap a spec B 6mt into a 5mt LGT? (Same year) labor only as I'm providing all the parts.

 

I got a quote and the hours seem a bit high.

 

Not really trying to do this swap outside in the middle of winter but this quote is making me consider it.

What would you all expect to pay a shop to swap a spec B 6mt into a 5mt LGT? (Same year) labor only as I'm providing all the parts.

 

I got a quote and the hours seem a bit high.

 

Not really trying to do this swap outside in the middle of winter but this quote is making me consider it.

 

By memory, this work includes harder parts and easier parts.

 

Easy:

 

1. Remove rear CV axles and rear diff

2. Remove drive shaft

3. Install reverse light switch on 6MT

4. Remove front axles

 

 

Harder:

 

5. Remove 5 MT tranny and 5MT shifter and 5MT shifter trim from the car

6. Remove 5MT specific clutch from engine

7. Install 6MT specific clutch on engine

8. Replace 5MT tranny mount with 6MT tranny mount on tranny cradle

9. Replace 5MT clutch slave cylinder and hose with 6MT specific slave cylinder and hose, flush the fluid

10. Install 6MT tranny and 6MT shifter and 6MT shifter trim on the car

11. Reinstall rear CV axles and rear diff

 

Easier again:

 

12. Reinstall front Cv axles

13. Reinstall drive shaft

 

 

It's not a small job job when you consider all details.

Edited January 12, 2021 by SubOperator

17 hours of labor just sounded high....

Consider that most clutch swaps are going to cost you about a thousand bucks. I’d say $1500-1700 would be fair.

17 hours of labor just sounded high....

 

 

Agreed. A shop should be able to do it in a day or less with couple of hands. They are probably padding a little for unforeseen delays. But then again 2 hands for a day is 16 man hours. What's the rate they are giving you?

$120 an hour, which is about average for the better shops around here.

 

I could get it done in 17 hours with a lift and tranny jack.

 

I was figuring $1500. My problem comes when it blows right past their estimate. (Like it always does at shops)

Two people all day is 16 hours.

It doesn't sound far off to me.

If I thought (or was even suggested) it would be done in one day, I would not have an issue.

 

I asked for a break down of where those 17 hours were being spent and got zero response.

 

 

I'll probably still end up doing it so I have my car back before spring, but my gut tells me we'll be closer to $3k than $2k when all is said and done.

15-20 hours would be normal charges for a shop to do a full swap.

Seeing all these costs makes me glad I do most of my own work...even if it takes awhile to get things done.

Seeing all these costs makes me glad I do most of my own work...even if it takes awhile to get things done.

Some of us aren't that patient (and really don't have the time)

 

I'll end up paying I'm sure.