atchipmunk

did the swap yet? kind of wanted to see your DIY walkthrough before I proceed..

Unfortunately I haven't gotten a chance to do it yet. Just haven't had the time. Was actually gonna try to do the swap this past weekend, but completely forgot to bring my brake bleeder home from work on friday. :mad:Maybe i'll get to squeeze it in next weekend...

sjwelna...thanks for the post and pics. Great comparison of the two boosters...was planning on taking some similar pics when I did mine. From your pics it looks like the STi booster and M/C combo might be a little shorter than the LGT booster/MC. Is that the case or is it just the angle of the boosters, etc in the pics? Just trying to deduce whether the GrimmSpeed MC Brace will work with the STi Setup.

As a follow up the 'nothing happening' at the top of the pedal travel I am almost sure is 100% the booster. When I had everything apart I could push the rod that bolts to the brake pedal in a little ways before it started to move the rod that pushes on the master cylinder. I wish I knew how to make that takeup less, that would make the brakes even better. The upside of having that bit of travel before the brakes bite is that the brake and gas pedals aren't at really different levels, which means you can still heel-toe without having to really crank your foot into a weird position.

I'm wondering if lengthening the pedal rod on the booster a little bit from the recommended length might work to reduce that pedal travel, however I know from the other STi Booster/MC thread that some people that didn't adjust that rod to proper length have had issues with the brakes locking up after a period of driving. Was probably enough to be constantly sightly applying the brakes causing them to overheat. Hmm...might play with that length a little when I do mine...

One last thing...any chance you got to check if the LGT fluid reservoir would fit onto the STi Master Cylinder? My '06 STi Master Cylinder didn't come with a reservoir and i'm wondering if I can just swap the LGT reservoir onto the STi Master Cylinder. The spacing of the ports looks pretty close between the two but haven't gotten to actually take any hard measurements or actually try fitting it. Anyway, thanks again for the pics.

On a side note, from the two people I met at a local meet today who's done the Grimmspeed Master Cylinder Brace mod, they said it made a tremendous difference in brake feel. They swear by it.

Yeah, I'm actually interested in eventually running the GS M/C Brace in conjunction with the STi M/C and Booster. I actually posted in the GS Brace thread but as far as I know no one has tried using the brace with the STi M/C Booster swap. Even the GS guys weren't sure if it would fit. When I do my STi M/C and Booster swap gonna be taking a bunch of pics and measurements so I can compare the location of the M/C swap compared to the stock M/C to determine if the GS brace will fit. I suspect that it will, but there's only 1 way to know for sure...

This might help for people unsure of the rod length on the booster

That from the Legacy's repair manual or from the STi? I wonder if they list different measurements for each ?

Ok, flushing the M/C is merely a matter of pushing clean fluid through the M/C to push out the dirt and crud, etc. You could use the traditional bench bleeding technique and keep filling the reservoir and pushing fluid through the M/C till no more dirt, etc. comes out. Since my STi M/C didn't come with the reservoir, I couldn't do it that way. So, I found a container that just fit the M/C in it...filled it with brake fluid and sat the STi M/C in it...

http://i277.photobucket.com/albums/kk56/atchipmunk/05%20LGT%20Wagon/MCflush-1.jpg

Then it was just a matter of depressing the piston in the M/C to suck in and push fluid through the M/C. The fluid in the container would obviously get dirty from the fluid being pushed through the M/C and I would just empty it and replace the fluid with fresh brake fluid until no more crap came out. I actually had to refresh the fluid at least 7 or 8 times before no more crap came out. Anyway, that's it in a nutshell. Unfortunately, I forgot to take any pics of how dark the fluid got while I was doing it since my hands were covered in brake fluid, etc. I can tell you that it was pretty ugly and i'd hate to have pushed that crap into my brake system had I only done a bench bleed to fill the M/C with fluid...

Yeah, originally I was thinking about using the stock LGT check valve and running the side that usually goes into the booster into a hose and then running that hose to the STi booster. Problem is that that end is larger and would require a 1/2" ID hose, where the STi booster port is for a 3/8". I could make I work with some step-down adapters, but in the end it would look a bit hobbled together (read: ghetto-rigged). I'm a stickler for things looking "right" so that's kinda outta the question.

Anyway, I'll post a pic of how I flushed my M/C when I get back home to my computer later...

One other thing for anyone looking to do this swap...

Depending on where you get your parts from, in addition to bench bleeding the M/C you might also want to consider flushing the s**t outta your master cylinder as well. Most of us will probably buy these parts from a recycler or off of ebay, etc. The problem with these places is that they pull the parts and store them. Depending on how they're stored, crud and contamination can develop inside...especially since brake fluid is hygroscopic and absorbs moisture from the air. When I got my STi M/C there was A LOT of contamination inside of it...almost looked like they stored the damn thing outside in the rain. I used a LOT of brake fluid to flush out the thing MULTIPLE times and you shoulda seen the crap that came out of this thing...definitely not stuff you would want to push into your brake system. Just doing a regular bench bleed wouldn't have done it either. Anyway, I took a pic or 2 of how I flushed it so when I do my DIY Walkthrough i'll post those as well...

Also, the reason why this is necessary is because the OEM legacy brake booster has the check valve built inside the booster. Where as on the STI Booster, it's located inside the vacuum hose. So when you swap to the STI setup, you also need to put the check valve on the vacuum hose. Hope that makes sense

Well, that's not exactly correct. On the Legacy, the brake check valve is not built inside of the booster. It is external to the booster, but uses a different type of mounting than the STi booster. The LGT check valve is on the end of the hose and is press-fit into a rubber sealing grommet on the booster itself. On the STi Booster, there is a 3/8" Hose connection for the vacuum line. I'll take some pics of both to show what i'm referring to...

I'll actually be doing this swap either this week or next and going to take a lot of pictures and measurements and will be writing a DIY Walkthrough of the whole process. I'm not going to use the STi check valve though. I'll be using an inline brake check valve from either a Toyota Supra or Nissan S13 or S14...

Sorry I misunderstood. Makes sense. I should be getting my booster/MC combo within the next week. If you have not found the answer by then, I can take a look at both of mine if you'd like.

Well, I looked up the pats on OpposedForces and it lists different part numbers for the '05 LGT brake reservoir and the '06 STi brake reservoir. (26451AC010 for the LGT and 26451AC000 for the STi). Now my question is...will the LGT one work on the STi M/C? The port holes visually "look" to be in the same location, but who knows...would have to actually try to fit the LGT one to the STi master to know for sure, but since the one is still installed on my car I can't easily do that. Hmm...was gonna try to do my Booster and M/C swap this weekend, but maybe i'll have to wait and just get myself an STi reservoir. Would hate to take it all apart only to find that the reservoir doesn't fit...

He's asking about the reservoir, not the mc and booster bolting together.

Yes...just asking about the reservoir itself...NOT the M/C since I have both the M/C and Booster from an '06 STi...

Great...another mod I need to add to the list.

Ever since I picked up my '05 LGT Wagon a few months ago, one of the weakest points to me on the car has been the brakes and their "feel" (or lack there-of). My other car is a AC Schnitzer Widebodied E36 M3 that has a Brembo GT BBK and that thing has amazing stopping power and feel. Makes the LGT feel like trying to stop a schoolbus in comparison.

If the STi MC and Booster will improve the responsiveness and feel of the brake pedal then that's definitely something i'll have to look into adding to my LGT. Thanks a lot to those that pioneered this swap!

Someone feel free to factcheck me if I'm wrong. But I was always taught to plumb the auxiliary cooler in before the one in the radiator. This helps is done to help regulate the transmission fluid temperatures as ambient temps can have a wild effect on fluid temp throughout the seasons. Since the coolant in the radiator is basically a thermal mass that is a more consistent temperature as compared to ambient temps is can help prevent overcooling or continue to help any further reduction. The basic premise however being not only cooling of fluid temps but regulation as well.

Yeah, there are definitely 2 schools of thought on this. The transmission fluid can be too cool, and if I lived in an area that saw all 4 seasons and had to worry about the fluid being cooled too much during the winter months I would probably opt to plumb the aux cooler in before the stock cooler so that the stock cooler could help regulate the temp. Here in sunny SoCal that shouldn't really a problem, hence the choice to plumb it after the stock cooler...

Disclaimer: I take no responsibility for any damage you may do to your car following this DIY. Any work you do on your car, you do at your own risk.

When I bought my '05 Legacy 2.5GT Wagon recently as a more "family" oriented daily driver, I was forced to opt for an Auto Tranny because the wifey can't drive stick. After catching a bit of the mod bug for this car, I read of some of the problems 5EAT owners have had with the increased power levels of anything over Stage 2 and figured a trans cooler would be a good addition to help dissipate heat from the trans fluid (also looking at a HexMods F1 Modded Valve Body and maybe a trans rebuild eventually). Searched on here and found an install thread with a dead link, but a google search led me to this pdf: subaru.rockhopjohn.com/Transcool.pdf

It's a pretty good install how-to, but IMHO the cooler was plumbed incorrectly (more on that later). I just did a similar install and figured i'd post it up here since the link in the other thread is dead.

Most of the people that have added trans coolers have done so using the Hayden 1676 or the 676...the smaller of the 3 sizes that Hayden offers. I wanted to try to fit a bigger cooler (was looking for a 677) and the only thing my local auto store had in stock was the 678. People have stated that this cooler would be too big to fit the LGT, but a rudimentary measurement of the available space suggested it may fit afterall. Plus, it was the only thing they had in stock, and I wanted to do this install today (had a little bit of spare time today - very rare with 2 kids:D), so I bought it along with a little extra ATF. Here's the Hayden 678:

http://i277.photobucket.com/albums/kk56/atchipmunk/05%20LGT%20Wagon/TransCooler-1.jpg

And here's what the cooler itself looks like:

http://i277.photobucket.com/albums/kk56/atchipmunk/05%20LGT%20Wagon/TransCooler-4.jpg

Included in the kit is the cooler core itself, 4ft of hose, 4 screw-type hose clamps, and the mounting clamps for the cooler. The other thing you'll need to buy is a 3/8" barbed hose union, like this (you only need one):

http://i277.photobucket.com/albums/kk56/atchipmunk/05%20LGT%20Wagon/TransCooler-2.jpg

So, I started by opening up the hood and removing the front grill to access the area where the cooler will mount. I chose to mount it in front of the driver's side of the condenser. Here's the space i'm looking to mount it:

http://i277.photobucket.com/albums/kk56/atchipmunk/05%20LGT%20Wagon/TransCooler-3.jpg

I ran the hoses to the core, secured them with hose clamps, and fed the cooler into place. I'm not really a fan of the clip mounts they provided for mounting the cooler to the condenser/radiator, but there aren't really any available empty threaded holes in the surrounding area that I could fabricate brackets to, so I just used the supplied mounts for now. Follow the manufacturer's instructions for proper usage of these mounts. Here's the cooler mounted in place:

http://i277.photobucket.com/albums/kk56/atchipmunk/05%20LGT%20Wagon/TransCooler-5.jpg

Yes, it BARELY fit in there. Honestly, it's actually a TAD bit to big. The core itself is perfect, but the hose connections actually slightly contact the hoses/mounts on the condenser. To help prevent it from wearing holes into the hoses, I put some isolating pieces in between the hose and the condenser mounts. I'll keep an eye on them to make sure they don't cause any issues, but it should be ok. In hindsight, it probably would been better to go with the Hayden 677 or the more commonly used 676, but oh well...on to the plumbing!

The LGT with the 5EAT already has an liquid to liquid trans cooler built into the bottom of the radiator using engine coolant to pull heat from the trans fluid. When adding an auxiliary liquid to air cooler to this circuit, you want to plumb it in in series after the stock cooler, before the fluid returns back to the transmission. This gives the most additional cooling capacity. The line that needs to be tapped into sits on the driver's side front corner below the framerail and battery. I was able to access it and do all the work from the top side of the car and didn't put the car up in the air at all. In order to access it, you must first remove the coolant overflow tank. To remove it, pull the hose from the top of the tank and press the retaining tab to release the corner of the tank. It then just pulls out of place. Here's a pic:

http://i277.photobucket.com/albums/kk56/atchipmunk/05%20LGT%20Wagon/TransCooler-6.jpg

Once the coolant tank is out of the way, you can see the trans cooler lines towards the bottom of the car. They can be seen here (2 hardlines coming down off the framerail connecting to 2 rubber hoses):

http://i277.photobucket.com/albums/kk56/atchipmunk/05%20LGT%20Wagon/TransCooler-7.jpg

The rearmost hose (top one in the pic) is the return line back to the transmission from the stock cooler. That is the one we want to tap into. It is held on by a squeeze clamp. Squeeze the clamp with a pair of pliers to release it and slide it downward and remove the hose. At this point, I plugged the stock hose with an appropriately sized bolt, and capped off the hard line with one of the plastic caps that came on the hose connections on the cooler core. This helped to minimize fluid loss while I was trimming the auxiliary cooler lines to the proper length.

About those lines. I mentioned earlier that I thought the cooler in the other .pdf was plumbed incorrectly. I say this because it was plumbed so that the fluid flows from top to bottom of the cooler before it heads back to the transmission. While there is much debate to which direction the fluid should flow through an auxiliary cooler, IMHO the proper flow is from the bottom up. The reason is to ensure it bleeds air properly as any air bubbles in the cooler core will reduce it's cooling effectiveness. Flowing from bottom to top practically ensures that the cooler will be bleed as it's much easier for the fluid to push air upwards (the direction it naturally wants to travel) versus pushing it downward through the core. That being said, we want to connect the upper hose off of the trans cooler (the outlet hose) to the hardline side of the return line. On the lower cooler hose you want to install one of those 3/8" Barbed Unions using hose clamps (don't tighten them too much) and connect it to the rubber side of the return line coming from the stock cooler. Here's what mine looked like after I connected the lines:

http://i277.photobucket.com/albums/kk56/atchipmunk/05%20LGT%20Wagon/TransCooler-9.jpg

And another one from a different view:

http://i277.photobucket.com/albums/kk56/atchipmunk/05%20LGT%20Wagon/TransCooler-10.jpg

Now, all that's left to do is to make sure the hoses don't contact any sharp edges (using zip ties to hold stuff into place if necessary), top off the transmission fluid (make sure it's at operating temp when you check the fluid level), re-install the coolant overflow hose, and enjoy the added cooling for your trans fluid. You'll definitely want to double check all your hose connections after starting and running the car to make sure they don't leak.

Total work time for me was about an hour, including clean up time of the fluid that did spill from the hoses. If I had even more time to work on it, I woulda chose to pull the radiator so I could mount the cooler to just the condenser using the supplied clips and not through both the condenser AND radiator. Maybe if I ever upgrade my radiator with an all aluminum one, i'll do just that. Anyway, I hope this helps anyone looking to add a cooler to their car...

Alvin Caragay

Hermosa Beach, CA

'05 BSM LGT Wagon (Cobb OTS Stage 1 tune)