twowings

It appears that one of the choices for 2014 is the NA FB25 with 6spd MT...

I'm thinking that tranny would be a great swap-in candidate for 09-13 FB 5MT or, even better, a crate tranny with a Subaru part number that can be ordered.

Anyone else here thinking the same thing ?

flstffxe

It is likely a variation of the Legacy 6mt that has been out for a while.

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twowings

Thread Starter

Which 6-spd tranny Sti or Impreza would be a better all-round choice for someone wanting to cruise all-day at 65 mph/2100 rpm and have great mid-range power?
I'm not interested in stoplight-to-stoplight drag-racing prowess or top-end speed ....

Loscaldazar

The STi 6-speed would be a waste in a N/A Forester. The lightweight 6-speed that is coming in 2014 (and most likely, as already stated, is the same/similiar to the legacy/outback 6-speed manual) will be the best for fuel economy and quietness on the highway. The STi 6-speed would be faster than any other manual, but the lightweight 6-speed will probably be faster than the 5MT, and obviously better than the 4EAT or CVT.

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Lone Ranger

Does "light weight" mean weaker and easier to break [than the 5MT] under spirited use though? And would it bolt up to an EJ25?

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dpm

well it can handle the Diesel's torque...

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2009 SH XCdiesel 6MT

Loscaldazar

Lightweight means it's not the hand built STi unit. It without a doubt is better than the 5MT in terms of strength. My guess is that it would bolt up the the Ej25, as the 2010-2012 Outback/Legacy had the 6-speed manual with the EJ, and now the FB engine with a 6-speed, and as far as I know, it's the same transmission.

And Dpm, is this actually the same one that is hooked up to the diesel engine? If so, then it probably would be a good choice to swap for a few WRX guys with 5-speeds.

Also, seeing as how the new FB and FA engines are very easy to turbocharge (even if they came N/A from the factory) I see aftermarket turbo set up getting more popular for N/A guys, and maybe even draw several people to buy the N/A with the 6-speed and turbo it....Hmmm....

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Lone Ranger

I am liking this thread.

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twowings

Thread Starter

Maybe the resident Subaru Parts person(s) here can find out about purchasing the tranny directly ??

Loscaldazar

Might not be avaible for a few months-year as Subaru's are selling like crazy, and spare engines and tranny's are in short supply. I was talking to a guy who got a fluke lemon 2012 impreza, and it took over 3 months for them to get a 5-speed tranny to replace his with (clutch came apart and destroyed most of the tranny)! And that was an "emergency need parts now" repair kind of thing, not a "I want to buy a 6-speed because race car!"

I agree however, the 6-speed in previous generations would be cool. Not sure about cost effectiveness, but eh, who cares!

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twowings

Thread Starter

I really believe this FB engine could pull a 6th overdrive gear fairly well until you got into the upper end of the weight rating...I've got great midrange passing and acceleration in 5th gear even pulling a 4x8 utility trailer loaded with furniture and 4 passengers...

I've started a '6-speed tranny fund' in anticipation...SubaruPartsGirl is on the case and when the parts inventory starts to build for 2014s I hope to put a swap together with someone who needs a 5-speed replacement....stay tuned !

Rand

I've been driving a 2013 outback with the fb25 and the 6mt.

you dont use 6th until at least 70mph unless its totally flat terrain.

twowings

Thread Starter

Isn't the Outback somewhat heavier than the Forester ?

The Sub

No more than about 150lbs heavier than a comparable SH Forester...

Subaru 2013 Outback research webpage- specs, options, colors, photos, and more

My 2011 with its options is about 3340lbs...the Outback with similar features is about 3500. That is one passenger more.....so, not much. I am interested in this swap, but wonder about switching the AWD from MPT to center diff + LSD....plus, probably TCU, etc. Might be easier to just buy the car with the engine/trans you want......wait, that's no fun!! :P

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Duderotomy

Hey guys, the 75mm 6MT that is coming in the new Forester is the same unit that comes in the Legacy, Outback, and diesel Forester.
The only version that will give the "overdrive " effect you're looking for is the diesel Forester versions. Every other iteration uses very similar 6th gear ratios to the normal 5th gear in previous gearboxes.
also, the 75mm 6mt is based on the 75mm 5mt. The STi gearbox is a completely different 85mm unit which uses larger diameter gears.

It has yet to be determined whether the 75mm 6mt is stronger than the 5mt. They're designed similarly using a split-case design, which isn't the strongest. The new gearbox has yet to be truly proven at higher power levels. The diesel has been a good test, amd the MY10 Legacy GT guys have only pushed as far as 400 lb-ft of torque. That specific LGT was sold off before they could conduct any durability tests on the gearbox.

I don't specifically know whether they retained the same gearbox length of the 5mt, but if they did then it will inherently be weaker than the 5mt since gears would have to be narrowed in order to fit everything into the transmission case.

Essentially though, if the gearbox still only has a 6th gear ratio of 0.7xx on a 4.111 final drive then it isn't going to be much more efficient on the highway than outgoing models. The extra gear allows them to space the other gears for better fuel economy.

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