Hello everybody, my Name is Tony, die hard Subie fan, I am in college for an automotive technology associates degree. I am writing a paper, simple one, about the 5-speed manual in the 1999 Impreza Outback Sport. I am finding information a little scarce, such as, the models this was used in, and reasons for changes in gear ratios. So if any of my fellow Subaru people have any information, or advice I would greatly appreciate it.

Perhaps you could do your report on the dual range transmissions from ea81 and ea82 subarus, and some sot of evolution of the trans to the impreza platform. This is where the impreza transmission derives from, and can even be hybrided. PErhaps a report about the subaru transission in general, as it is atypical of most other automotive platfroms. Write about the center differential and how the platform is AWD with no transfer case, and how it differs from other platforms with equal distribution across all differentials.

 

Threre are gear ratio charts posted that you should be able to find. Good luck with your paper

I appreciate the help and input, however, I need to address one transmission, and the 5MT is what I picked. Again it just needs to be a basic paper, with a touch of evolution.

Also include some argument in there about how america missed out on the dual range AWD gearbox from the EJ series making note of how this would have benefitted many subaru fans as found on this site.

 

Here's a pic of an EA82's dual range 5 speed gearbox (85-94 model run) front section, the rear housing has to be removed to get to the front casings to split them like this:

 

 

And here is a '94 model liberty/legacy AWD dual range gearbox, rear housing removed again to get to the front cases to split the gearbox:

 

 

What are the differences you ask? Apart from some slight changes to the front casing design for bolt stud patterns, the rear housings changed to accommodate the centre diff (but retained the same rear bolting pattern )

 

The top image is the PT4wd gearbox derived from the L series. On the other end of the pinion shaft from the diff is the gear that powers the rear end once the engaging mechanism locks the gearbox to the rear drive.

 

The lower image has several splined shafts that are stubby compared to the length of the shaft with the gear on the end of the L series' gearbox. This is because the lower gearset is effectively mounted on a tube that has the pinion shaft pass through it to the front diff. This allows the pinion shaft and the lower gearsets to spin at different speeds independently of eachother.

 

The splined ends opposite the diff is where the center diff mounts - the spline on the far left is the pinion shaft and the spline just to the right of that is the lower gearset that drives the centre diff before power goes to the front and rear as derived by the centre diff.

 

Ultimately the the overall design of the gearbox remains unchanged until you get to the six speed gearbox. The US market didn't get the low range gearing that you can see mounted above the front diff, so there's only a straight shaft in there.

 

As you've already mentioned the gear ratios do change - this will be determined by which model the gearbox was destined to be in and what power plant was mounted in front of it as well as the market demographic it was aimed at. Probably all the things you're looking at in your paper I would imagine.

 

I hope I haven't wasted your time with this essay on what we've got over here in comparison to what you received over in the US, but I thought it might have been useful/interesting.

 

Cheers

 

Bennie

Are you at Ferris State?

 

Good info

 

 

The biggest variations of the transmission were if it was in an outback or not, and if the powerplant was turbocharged.

I am finding information a little scarce, such as, the models this was used in, and reasons for changes in gear ratios. So if any of my fellow Subaru people have any information, or advice I would greatly appreciate it.

 

The AWD 5MT was used in everything that had a manual transmission (in the US).

 

Gear ratio changes are based on the vehicle power, weight, tire size, and how sporty/economical Subaru wanted that model to be. They are completely variable and transmissions can be found that run the spectrum from short-ratio sports car gear ratios that top out at 120 MPH to ones that are designed for longer ratios that provide better fuel economy.

 

It was a standard platform that was used on all manual transmission Subaru's - you can't really tie it down to the '99 Impreza OBS.... that same basic unit is still being used - it has been almost unchanged since 1990 and it derives it's basic design from the part-time 4WD 5MT's first introduced in 1985.

 

GD

This is exactly the kind of stuff that I was looking for, you guys are awesome, and I am at Muskegon Community College, my teacher is going to Ferris though. Thanks much.

Is your teacher a Prof there or a student?

He is a student at ferris.

wiki has a pretty good sized write up on the subi 5mts if you havnt ran across that yet

wiki has a pretty good sized write up on the subi 5mts if you havnt ran across that yet

 

Thanks much, I did find that just a little bit ago.

-Tony

Also include some argument in there about how america missed out on the dual range AWD gearbox from the EJ series making note of how this would have benefitted many subaru fans as found on this site.

 

Here's a pic of an EA82's dual range 5 speed gearbox (85-94 model run) front section, the rear housing has to be removed to get to the front casings to split them like this:

 

 

And here is a '94 model liberty/legacy AWD dual range gearbox, rear housing removed again to get to the front cases to split the gearbox:

 

 

What are the differences you ask? Apart from some slight changes to the front casing design for bolt stud patterns, the rear housings changed to accommodate the centre diff (but retained the same rear bolting pattern )

 

The top image is the PT4wd gearbox derived from the L series. On the other end of the pinion shaft from the diff is the gear that powers the rear end once the engaging mechanism locks the gearbox to the rear drive.

 

The lower image has several splined shafts that are stubby compared to the length of the shaft with the gear on the end of the L series' gearbox. This is because the lower gearset is effectively mounted on a tube that has the pinion shaft pass through it to the front diff. This allows the pinion shaft and the lower gearsets to spin at different speeds independently of eachother.

 

The splined ends opposite the diff is where the center diff mounts - the spline on the far left is the pinion shaft and the spline just to the right of that is the lower gearset that drives the centre diff before power goes to the front and rear as derived by the centre diff.

 

Ultimately the the overall design of the gearbox remains unchanged until you get to the six speed gearbox. The US market didn't get the low range gearing that you can see mounted above the front diff, so there's only a straight shaft in there.

 

As you've already mentioned the gear ratios do change - this will be determined by which model the gearbox was destined to be in and what power plant was mounted in front of it as well as the market demographic it was aimed at. Probably all the things you're looking at in your paper I would imagine.

 

I hope I haven't wasted your time with this essay on what we've got over here in comparison to what you received over in the US, but I thought it might have been useful/interesting.

 

Cheers

 

Bennie

 

This was much help, I will cheerfully use the information you have so graciously provided. In my manual transmission class we just had one of these apart and rebuilt it, so it looks striking familiar, all except the extra gears, have a great day.

 

Cheers,

-Tony

Edited July 8, 201114 yr by SubieTony77
More info

The AWD 5MT was used in everything that had a manual transmission (in the US).

 

Gear ratio changes are based on the vehicle power, weight, tire size, and how sporty/economical Subaru wanted that model to be. They are completely variable and transmissions can be found that run the spectrum from short-ratio sports car gear ratios that top out at 120 MPH to ones that are designed for longer ratios that provide better fuel economy.

 

It was a standard platform that was used on all manual transmission Subaru's - you can't really tie it down to the '99 Impreza OBS.... that same basic unit is still being used - it has been almost unchanged since 1990 and it derives it's basic design from the part-time 4WD 5MT's first introduced in 1985.

 

GD

 

And that information is identical to what I have been finding, I do appreciate the coordinating information about the platforms.

Thanks much.

-Tony