How do I make my car have more top speed?

At the moment Im restricted to 137 mph. at 7500 rpm

I have a 96 RA DCCD transmision?

Thanks

change your rev limit to 8K or 8500 or something.

I will, when I put the FC but a 300rpm+ whont do much.

Whats your final drive? 4.44? 4.11? 3.9?
Sounds like it might be a 4.44. If thats the case, change the ring and pinion.

3.900

HolyMoley. RAs are short!

I'm not a trans expert, so don't go off what I am saying. But you might wanna consider a 4th and 5th from a non-RA car. WRX or STi. Although I am not sure what is compatable with your transmission so I can specify what gears will work.

I've got the same tranny...but no DCCD, and mine is a 4.11 FD. I too would like to make mine longer. What is involved in making it 3.9...just swapping out the ring and pinion? Is that difficult?

front FD and rear FD need to be changed to whatever.

i got 4.44 and don't mind too much the highway cruising RPM's. i still got 4K RPM's to pass someone even at 80 MPH.

but 4.1 or 3.9 would be a little better if i always did highway trips.

--keith

It's more the gas mileage and increased engine wear that bothers me. I do a lot of highway trips...most of my clients live about 50+ miles from me.

wear yes. mileage. probably won't change too much.

my 98 OBS gets 20-32(worst avg. and best avg.)@3.9 FD

my V4 STi gets 18-30(worst avg. and best avg.)@4.44 FD

just my experiences so far.

--keith

Would making the tranny 3.9 be as 'simple' as swapping out the ring and pinion?

tranny cracking isn't my bag. the R&P would be easier to swap than the tranny's FD ratio would be.

the diff is easy to get at. just pull the axles out and remove the rears mount bolts(may be rusted) and carrier frame thing to drop it down. easier and lighter than removing the trans. and opening it to change it's ratio. but if you want 3.9 in an STi/WRX trans, you'll have to open it anyway. you can't just change the front or just the back.

--keith

I know I could just get a 4.11 diff and all would be good, but it's just too short overall. The car is actually a 3.9 currently and I thought I was going to have to make everything 4.11. If I could make the tranny 3.9, that'd be great. A buddy of mine that lives with me is a mechanic, and another dude I know has done a few tranny swaps, so I am thinking we would be able to to the R&P, but I really don't know what is involved.

R&P is an easy task. especially for your mech. friend. it'll help a little bit with less shifting, but after a while it's imperceptable at best. 1/4 mile times would show the difference in a big way by having in your face numbers from(apple to apple comp.) the same setup with 3.9 and 4.11 FD's.

Can I take the R&P out of the stock '92 Legacy 5mt and put that in the JDM RA box or will I have to source a specific one?

thats a big? here. im not 100% a non factory LSD diff is capable of accepting an LSD. i would think is kind of stupid not to be able to, and very un-SUBY like to boot. i just don't know.

--keith

Well, I did some calcs and as someone was saying, there isn't a ton of difference between a 4.11 and 3.9 (maybe a couple-few hundred RPMS) So it is something, but not what I am wanting. That being said, I think my best bet is to look into trading/selling the JDM RA box I have and getting an '05+ WRX tranny.

Are there any writeups on the R&P swap though? I'd really like to read a play-by-play of what is involved.

Isn't the wrx 3.54FD? You could change it to that

Isn't the wrx 3.54FD? You could change it to that

That would prolly make enough of a difference. I'd need to get the R&P out of the tranny, and other parts to make the rear match though. The car is already 3.9, so I figured it'd just be easier to sell/trade for a WRX tranny.

Kheff had the right idea. Listen up.

You must have the same final drive front and rear. You must also consider the transfer gears(behind the center diff). You must verify your setup and you must get it right or you'll be replacing your center diff.

If you have a 3.9 front r&p and a 1.1:1 transfer, then you must use a 3.54 rear r&p.

If you have a 3.9 front r&p and a 1:1 transfer, then you must use a 3.9 rear r&p.

rs's typically have a 1:1
wrx's typically have a 1.1:1

You cannot just swap out a rear r&p unless you can make it work mathematically with a transfer gear swap. Also, your probably not going to get it right just swapping the r&p. Just swap the whole diff carrier and change over the lsd if you have one.

I'm not too up on what the new legacy or the forester final drives are (front/center/rear), but they can be considered.

Front r&p swapping is not out of the question but you must then verify your pinion depth and bearing preload prior to reassembly(requires a special tool). The pinion shaft does come free of the driven shaft with the removal of a nut though so no gear pressing would be involved. There is more involved Which requires more special tools. I would not go this route unless you are very comfortable with the guts of a 5mt.

Replacing your 5th gear would also be beneficial but does require some work. They are external of the main trans case so you could theoretically swap them in the car.

Good luck and someone post up forester and legacy front/center/rear ratios.

Also, I don't think pre 99 parts are usable in newer transmissions.

What Tim said is the same as my mechanic told me, it a lot of work.
He even told me that he would prefer to use a diferent gear.

As a foot note. In his shop we used 98 WRX JDM gears in a a 2002 WRX, the transmision was very long, 5th gear needed more power than the car had to move fast.

I completely understand the issues with the front and rear needing to turn at the same speed. My Legacy is not new, it is a '92 SS. I was originally going to take the stock '92 Legacy SS 5mt fifth gear and swap it into the '96 JDM RA 5mt that I have. I was told by a mechanic; however, that the gears are not guaranteed to fit together properly and have very exact clearances they need to be at.

For clarifications sake, I know that the RA 5mt is 1:1, and I think a Legacy SS 5mt is also, though I am unsure.

Due to all the work that is involved either way I go, I am now moving in the direction of just selling/trading the JDM RA box for an '05+ WRX drivetrain.

How do I make my car have more top speed?

At the moment Im restricted to 137 mph. at 7500 rpm



How much faster do you really need to go? Are you on a track or just street racing? I am not trying to insult your skills but 137 is way faster than most people should be driving anyway -especially on the street.

Subarus are supposed to be fast 0-75 or so but never known for top end. Want top end speed, get a supra or skyline.

If you stick with the subaru, get a usdm (taller gears) six speed. Someone here will be more than willing to buy your five speed.

The 96 STI RA has a 3.9 FD. There is nothing longer to go to. you need different gears.

The 96 STI RA has a 3.9 FD. There is nothing longer to go to. you need different gears.

You are right; however, 5th gear had a ratio of .972. In the '96 STi RA. My tranny has a 4.11 FD. On top of that, it has the typical RA gear ratios wherein 5th gear is .825. Thus why I called it an 'RA' tranny. Perhaps I should clarify...this tranny is not out of an RA car model, but it does have the RA gears. It would have come out of a WRX, WRX V-limited, STi, or STi 555.

For the record though, most 'long' fifth gears in Subarus are a .738 ratio, which makes the biggest difference; however, the new WRX has a 3.7 final drive.

http://spda-online.ca/modules/tinycontent/rewrite/tc_28.html

http://forums.nasioc.com/forums/showthread.php?t=181343&highlight=wrx+gear+ratios

Can I use one of the new WRX gears in my transmision?

There are a lot of options for getting more gearing (in the form of different trans.) Swapping out individual gears (5th, 4rth and 3rd, 2nd and 1st) is technically possible, but is basically not worth the extreme risk. It is very easy for even a qualified person to mess it up. Going with an entire traditional ratio RA gearset would give you some more leg room. You may also consider selling your tranny and getting an '05+ WRX tranny. You could prolly buy the WRX tranny and have new bearings/synchros put in for what you could sell your RA tranny for. The two trannies should have about the same strength level...just different gearing. Keep in mind, if you go with longer gearing, you will lose acceleration, but will not have to shift as early and get better gas mileage.