Legacy Diffs ? yes or no
 

Just curious if anyone has gone all the way and changed over to legacy or forester diffs to improve gear ratio. In lurking on the forum these past couple months and reading old posts this appears to be an unresolved topic. I have become a recent SVX owner and since an efficient turbo setup appears to be unrealistic from a price standpoint I am ready to use my 92 as the differential guinea pig and find out exactly what will work.Suggestions and comments welcome,its only money !:D

Dffs question
 

The only problem that I can think of in switching to legacy diffs is that you'll either need to swap the ring and pinion into the rear differential case with the SVX limited slip components or you'll need to use the Legacy rear halfshafts. The halfshafts are different on the SVX because of it's limited slip rear diff. I'm not sure that the Legacy halfshafts are the same length or if they have the same outer joint and splines. I'm sure someone here will be able to cover those points though.
Good luck,
Jay

So the ring and pinion on the rear Will go into my SVX diff and I will be able to use the LSD carrier from my car ? How about front end,same scenario or are fronts interchangeable ? Do any legacys have LSD diffs or are we talking Forester stuff now. If we use Forester diffs then we move up to 4.44 gears correct ? I just dont want to make 20 trips to the salvage yard,I can take all the parts from both cars and bring back what I dont need,( I spend a ton of money there over the years,they treat me well ! ) Legacy stuff appears to be dime a dozen,setup is not a big deal if parts will work,I want to see this through with a Positive Yes or No answer,seems to be a good idea if it will all work. Time is not an issue,this is just a play car. Thanks !

Depends on whether you're talking about auto or manual vehicles. The autos typically have a slightly taller rear end... Forester and Impreza RS autos have the 4.444, manual versions of those cars have a 4.11. Legacy manuals have a 3.90... make sure you don't mismatch final drive ratios by mistake, it can get expensive. :D

Of course on the flip side, if you swap in a USDM WRX 5 speed, you can keep your rear diff, as the ratios are the same. The WRX has a 3.90 front diff, a 1.1:1 center stepdown ratio, and a 3.545 rear end.

Again Porter, it's not so simple. Gear ratios are NOT broken down by platform (Impreza, Legacy, Forester), but by model (Brighton, L, GT, Outback) and engine (1.8, 2.0, 2.2, 2.5).

I will agree that the drive ratios MUST match, front to rear.

Todd

Todd, basically if it doesn't have an EJ25 in it I wouldn't even consider it for a tranny swap. It makes little sense to use a transmission with gear ratios designed for a 98hp torqueless wonder in a car with 230hp and huge low end torque. The EJ25 manuals are barely up to the task.

Do people really consider putting a transmission out of a 1.8 into an SVX? Just because it will bolt up doesn't mean it's a good idea... ;)

I would think that a Legacy GT or Forester transmission would be the absolute minimum spec that would even be on the table in this discussion.

The only case in my entire statement where I was erroneous or unclear was the blanket "Legacy" statement where I should have specified GT to make it clear that I was referring to the 2.5 equipped car.

I think I made it blatantly clear when I put RS on the end of the "Impreza" there in my sentence that I was referring to the RS, or EJ25 equipped car, all of which came with 4.11 in the manual versions and 4.444 in the automatics.

My whole point in the post above was to point out that there were a variety of final drives available, and to be careful when mixing and matching parts from different vehicles. I think that was a valid point to make, and we've been down this road before. :rolleyes:

I researched this quite a bit before opting for the 5 spd. If I wanted to keep it an auto, I would go all the way and buy a Forester tranny and rear end with 4.44 and swap it in. Cost about $1300 for parts. Then you could sell your tranny to recoup some costs. Or, you could swipe the front diff off of the Forester tranny onto the SVX tranny and sell the Forester tranny. Good luck on finding just a Forester front diff without the tranny though.

I'm running one of those "wimpy" trannys in my SVX, although I'm pretty sure highpockets is refering to the automatics.

Lowering the gear ratio, will put LESS stress on the tranny, and I believe that all 4EAT (in the US) from 90-96 were the same as far as internals, the only exception was the SVX, Turbo Legacy, and the Mailcarriers Legacy's which were the same except they had one more clutch pack in them, not really stronger, just more wear area.

The SVX came with the 3.54's (not available on any other Subaru.

The Turbo Legacy came with 3.90's (alond with very few Plain Legacy's)

And Most everything else had the 4.11'sMost Legacys, and Imprezas

I have yet to find a set of 4.44's on anything pre-96 (in the US)

So the easiest and cheapest to come by would be the 4.11's, and yes they rear ring and pinion will fit in the SVX's LSD Rear Diff (as I have them in mine) and the front diff will bolt right up to the SVX tranny, make sure you get the Legacy (or Impreza) Flexplate.

Porter you, unlike most of the people here, know/care about the differences between the other Subaru lines. Most people here that I've met are more fans of the SVX than of the entire Subaru line and thus don't know/care about the difference that adding RS to a model name means. So, while RS makes it blatantly clear to you it probably doesn't make it so clear to other people here.

Our goal however is the same, to keep people from getting the wrong pieces if they intend to source the parts themselves for a swap.

I'm rather surprised to see that you are going to use (according to another of yor posts) the Small Car swap kit. You and Kent (Templar) obviously have fabrication capability and Impreza connections. I figured you'd do this yourself.

Todd

I think time and effort both come into play here. When I can afford it I will also go for the Smallcar kit as well.

I'm not going to reinvent the wheel (or tranny as it may). :D

I'd sooner support the company who put all the time and effort into this project and hopefully fund more new and interesting projects for our cars.

Arent all of the 5mt's the same regardless of the vehicle they come from? I know the final drive is different based on model, but the transmission itself is what I am asking about. What makes the 5mt in the 2.5L impreza different from the 5mt in a 2.2L impreza?

Mike

wow, that was weird...I clicked submit and Mike's reply showed up AFTER my just submitted post!

The gear ratios are different. It really depends on the year and trim level. The higher (numerically) the final drive, the less stress (on average) will be put on the gearset itself, based on the torque multiplication of the gearset. You need to work out the speeds in gear based on the gear ratios and final drive to figure out whether that gearset and axle ratio would be appropriate for the SVX. The last thing you want is to have a wonderfully operating 5 speed installed and realize that you are turning 4800rpm at 75mph and only getting 11mpg. :D

The STi 5 speeds are really not much different from the standard WRX boxes, but their taller final drive puts less stress on the gearset, and the gear ratios are chosen to match that specific final drive. I know in the case of the STis, the sedans and coupes in v4 and v5 actually had different gear ratios. The standard STi was a sedan, the coupe was an STi typeR and had shorter gearing. Shortest of all is the STi typeRA lightweight sedan, which has gear ratios that would be murder to a commuter and specially heat and cryo treated gear materials for strength. It is the only Subaru available with a "hardened" gearset but its gearing would unfortunately not be appropriate for the SVX. An interesting solution would be to source an STi RA box and swap the 4.444 front and rear differentials for Torsen or Quaife units with a 3.73 or 3.9 final drive. It would be the strongest solution based on a factory gearset.

The ultimate SVX 5 speed would be a Legacy or Impreza bellhousing with a Chalak or GimmeGears synchro gearset installed, and upgraded differentials. Gear ratios and final drive could be specified for the car. That of course would represent serious $$$.

You're correct, and I still may do it myself. I haven't gotten the chance to take everything apart and look at it yet. I'm running on the assumption that the tranny crossmember Smallcar is using is one of their own design... capitalizing on their investment in time and effort will allow me to streamline my own project, even if I don't end up buying a complete kit from them. I will of course be sourcing the other parts on my own... tranny, pedals, clutch master cylinder, etc. That stuff can be acquired pretty easily. I'd like to investigate Smallcar's mount for the clutch MC though... it says on their site that it's a machined piece.

Small car states that they cannnot/will not sell parts seperatly. Their crossmember requiers welding brackets to the floor of the car, I didn't like that idea but the pedal assembly and MC mount would be nice to have. I didn't get mine right the first time and have to try a different way to do it. It's also the worst part of doing the swap and took the most amount of time. The people who used the cable style had it very easy, not having to figure out a place to mount the MC and then lineing the pedals up with it.