Changing Gear Sets [Merged 11-7] transmission drive ratios

[Attack Eagle]

Gentlemen and ladies...
I ahve always wished my tsi awd had a 6th gear because of freeway cruise rpm (about 3k-3500).

I saw that TRE does offer a taller 5th option of 10% and of 25%
which would you go with as that 5th gear is a cruising gear? (they call it top speed)

I have noticed that noise increases at about 3000 rpm so I am wondering if I should go with the more agressive 25% to drop my rpms to 2600 at top highway cruise, but it would drop 3000 to 2250 which seems a little low.

anyone have either of these ratios in their transmission tat can give feedback?

if not opinions are welcome

remember this is my family's long distance driver not just a straight out performance car thus wwanting to enjoy a slightly more relaxed cruising speed of 75 -80 mph on those long all day drives.

 

[HokieDSM]

Well, a taller 5th gear would in theory get you a higher top speed for when you want to drive it all out

But as far as highway speeds - I think it'd be a good idea, because 4th will easily get you to the speeds, then the 5th would be quieter when you shift to it - since you'd be lower in the rev band.

Hrm - if you're lower in the rev band in 5th when cruising at highway speeds - I wonder if that'd increase highway fuel mileage...

 

[pneumo]

I have the 10% taller 5th gear in my FWD and I love it. My other DSM (AWD) still has the stock gear, so I get to compare the differences several times each week. I'd recomend the 10% taller gear, not 25%. With a 10% taller gear the engine turns about 600 rpm slower, which is just right. The lower rpm makes the whole car feel more relaxed, less strain, less buzz. Plus the jump between 4th and 5th isn't too big. If you got the 25% taller gear the jump would be huge. It would feel like you're either a gear too high or a gear too low.

My gas mileage went up a little I think. My driving habits changed drastically about the time I got the gear, so I can't tell for sure. All I know is my commute is about 90% freeway driving in heavy traffic, and I regularly get 32 mpg.

 

[Attack Eagle]

at 75 mph true speed I am showing 80 on the speedo and about 3600-3700 rpms. (225/45/17)
since awd run deeper gears than a FWD I am not sure that 10% would be worth it. itwould only be 3300 rpms not 2700 like a 25%.

that being said for fuel economy you are probably right that the 10% would be the way to go, 2700 rpms needs boost to pull the car up an incline and 3300 doesn't (probably why the ratios are set for cruising at 60-65...)

I was assuming they were not straight cut. since you have these gears installed can you confirm this? IF they whine they are straight cut, if not they aren't.

 

[pneumo]

True speed vs. indicated speed? That's confusing. All I know is when the car was stock the tach read 3500rpm when the speedo read 75 mph. With the taller gear the tach reads 2900 at 75 mph.

FWDs only have taller gears in first to 4th. Stock 5th gear in both the AWD and FWD will give you 3500 rpm at 75 mph. If you plan on always running with those size tires then maybe the 25% taller gear would be a better choice.

My taller 5th doesn't whine, and I've seen it, too, so I can confirm it is a helical cut gear. However, that doesn't mean the 10% taller gear for the AWD isn't straight cut. They fit differently, so they aren't the same gearsets. Contact TRE and ask them, they should know since they make them.

 

[Attack Eagle]

True speed vs. indicated speed? That's confusing. All I know is when the car was stock the tach read 3500rpm when the speedo read 75 mph. With the taller gear the tach reads 2900 at 75 mph.

FWDs only have taller gears in first to 4th. Stock 5th gear in both the AWD and FWD will give you 3500 rpm at 75 mph. If you plan on always running with those size tires then maybe the 25% taller gear would be a better choice.

My taller 5th doesn't whine, and I've seen it, too, so I can confirm it is a helical cut gear. However, that doesn't mean the 10% taller gear for the AWD isn't straight cut. They fit differently, so they aren't the same gearsets. Contact TRE and ask them, they should know since they make them.

there is a 5mph loss at 75 mph on 225/45/17s. for me that would be about 70 mph at 3500 which is the legal limit or under the legal limit in most places I drive... I usually run 80 mph indicated which is a true (real world/ radar verified) 75 mph...

I thought and correct me if I'm wrong that the difference in gearing was in the Final gear ratio... at least according to the manufacturers data... AWD run 3500 but a 10% drop would only net me 3200 not 2900 as you indicate on your fwd. perhaps the stock rpm was 3200 - 3300 on your FWD and the 10 would get me to the equivalent rpm as a FWD Turbo?
the pnly otherthing that would explain how an awd and a fwd could have the same rpm at the same MPH would be if the AWD run an 18% larger overdrive to make up for the lower final drive? ( just checked and the final drive is different with a taller 5th gear 0.666 vs 0.741)

Now if I can just figure out how you got a 10% increase to give you such a big difference in rpm of almost 20%... I guess you have the same fifth as an AWD now so you are seeing the 20% difference on the final gear... justas you would if there were a 1:1 gear in 4th... I never realized that 4th is an overdrive gear on a DSM too. (0.833 awd vs 0.888 FWD)

Final Gear Ratios
Talon/ESi
Talon/ESi Mnual 3.94
Talon/ESi Auto 3.75

TSi (FWD) Mnual 4.15
TSi (FWD) auto 4.38


TSi AWD Mnual 4.93
TSi AWD auto 4.42

http://www.imaxx.net/jeepeagle/talon/specs.html

according to this the fwd are already 18% taller than the awd & my 2% deeper tires thus my thinking that I could use the 25% instead to experience the same cruising rpm as the FWDs which are far more relaxed at the normal highway speeds of 75 mph.

anyway I am going to try and Contact TRE regarding whether or not the 10% and 25% are straight cut, but since your gearset is not straight cut, there is little reason the AWD would be. (at least on the 10%).
thanks for your feedback, it has been invaluable. I want to get to about 27 - 2900 rpm at 70 mph, and not be bizzing along at 35-3800 at "80"

 

[pneumo]

I'm glad I could help.

Your right about the final drive ratio, but the gearsets are also different. Check out www.VFAQ.com/mods/Trannies.html

Notice the 5th gear ratio between FWD and AWD? By itself the AWD 5th gear is actually taller by about 10%. The final drive ratio brings it back down. As it says at the bottom of that page, if you modify the FWD trans to accept the AWD 5th gear you get a 10% taller gear. That's what I have in my FWD. Unfortunately it doesn't work the other way around. Installing a FWD 5th gear in an AWD lowers the gearing. That's why I'm unsure of where TRE gets their taller gear for the AWD, and if it's straight cut or not.

 

[Attack Eagle]

I'm glad I could help.

Your right about the final drive ratio, but the gearsets are also different. Check out www.VFAQ.com/mods/Trannies.html

Notice the 5th gear ratio between FWD and AWD? By itself the AWD 5th gear is actually taller by about 10%. The final drive ratio brings it back down. As it says at the bottom of that page, if you modify the FWD trans to accept the AWD 5th gear you get a 10% taller gear. That's what I have in my FWD. Unfortunately it doesn't work the other way around. Installing a FWD 5th gear in an AWD lowers the gearing. That's why I'm unsure of where TRE gets their taller gear for the AWD, and if it's straight cut or not.

I just found that and was in the process of editing my previous post.

You got a (roughly) 20% improvement in 5th as compared to an AWD because you are now running the same 5th, and can see your 18% higher final drive in cpomparison...

That makes things more interesting... I on the other hand would only see a 10% improvement compared to myself or another awd. so I would be turning 3200 when you turn 2900...

How is response on the highway with your set up? Does it tip into boost on everyrise or does it only boost when you actually are going up a significant hill?

 

[pneumo]

18%? I always thought it felt taller than 10%, but I never crunched the numbers to see exactly how much taller it was. Thanks.

The response on the freeway has been reduced slightly. The effect is hardly noticeable at higher speeds. At lower speeds (55- 60 mph) the engine falls off the powerband. At that point I usually downshift to keep from lugging the engine. It didn't take me long to readjust my driving habits and anticipate the need to downshift. I have a 14b on the car now which helps response. I used to have a big 16g on the car and the response and drivability was similar, though full boost came later.



Another thing to bear in mind is the jump between 4th and 5th. The stock FWD has a small jump between 4th and 5th, so getting a taller 5th was no problem. But the AWD already has a larger difference. If you got the 25% taller gear would it be too much of a jump?

 

[Attack Eagle]

it might...

that would only come into play when slowing to 55-60 like you said and having to rev up to match rpms for the downshiuft to 4th...

I don't go to 5th until about 60 now... maybe the 10% would be a better idea now that i think about it... I think in 5th I would end up running slightly lower than you. about 2700 rpm.. I think that's a bit too much... cause you'd have to go to 4k+ maybe 5k in 4th before shifting up. no casual increase in speed, and no lygaging around in 5th in town at 50 -55 either.

Ill see what rpm Id run in 4th to get to 65-70 tommorrow and taking into account that it would drop to 2700 see how big of a gap there is...

but right now sounds like 10% (300 -400 rpm drop)will be the best option... wish it was 15-18% though.
that would be about a 500-600 rpm drop rather than 800... that's an awful lot on top of the regular rpm drop... I think i would fall completely off boost.

thanks again for your courtesy !
oh and by the way, what size tires are you running?
235/45/17 or 235/40/18? or stock sized?
the 225s give you about a 3 mph error + the normal 2-3 mph optimism inherent on every DSM I have ever seen. (we used to run by those road side radar stations to figure out how optimistic our speedos were so we could run right at the 3-4mph grace limit.)

 

[unlikely hero]

Alright well I just bought and installed a rebuilt tranny with a 10% taller 5th gear. I'm having a hard time determining if he really put one in. Right now my speedo isn't working and I drove around w/out 5th for like 4 months so I don't remember how it use to be. I have like a 1000rpm drop from 4th to 5th. Like I'll shift at 4k in 4th and it will drop to 3k in 5th. Would there be any other ways of helping determine if it really is a taller 5th. If it is well I'm not very impressed at all. Thanks for your help.
=Jason-

 

[tylerwal]

Before you start questioning someone's ethics, I would get that speedo working.

 

[1fast97gsx]

Before you start questioning someone's ethics, I would get that speedo working.

yep ... fix the speedo and then let us know at what rpm you are at at 100 mph and we can compare.

 

[bigfoot]

You don't need a speedo. You say you have a 1000 rpm drop from 4th to 5th, you have the 10% gear. Stock trannys have about a 500 rpm drop.

 

[unlikely hero]

Yea I need to fix the speedo but thats 100 bucks I don't have right now. Really stock wise its only a 500 rpm drop even for the awd tranny. I don't mean that he purposely ripped me off just that perhaps there was a mix up. BTW whats the rpms suppose to be at 100 I could always just have a friend drive at 100 and match his speed to see.
=Jason-

 

[gsxtacy]

I know for a fact my GSX will do 165 at 7400.

Find a friend and drive beside him at 165...if your tach is lower than 7400, you know they did the 10% over 5th gear.

Or....I know that cruising 70 mph in my 98 GSX...I am taching 3100 in 5th.

Which ever you feel safer with.

gsxtacy

 

[midnght]

I have the 25% taller 5th and at 65mph it is at 2100rpms. Drop it to 3rd and it goes to 3500rpm with instant reponse. 4h gear will pull as high as I need to go in a "spirited" driving session, 5th gear has now become my FUEL SIPPER, . It has also changed my driving habits drasticly from before it was in. I do not speed as much since the 5th gear acceleration is pretty mush non-existant and I can restrain from dropping it to 4th.


It is straight cut and does whine like a supercharger. Sounds pretty wierd. I thought something was wrong until I realized that it was a straight cut gear. Which is fine with me. I just turn up the music on the highway.

My car is not a track whore. And if I can hit 120mph traps with this LSD and 20g I will be happy enough to stop. I think 5th will pull at 120mph if need be, but I am not going to find out any time soon.

 

[noreaga0221]

Riding in both awd and fwd 1g's i see awds usually have higher revs for the same road speed vs. a fwd. but that contradicts the vfaq.

 

[BacknBlack92ESi]

Would the mph loss be much different on 18's?

 

[Attack Eagle]

awd's have a numerically higher (ie shorter/deeper) final drive than do the fwds... our gearing is taller in the tranny to compensate, but becasue of the additional driveline loss/inertia it is set so that it is still deeper (higher rpms) in any given gear and or mph...


the AWDs have an 18% deeper final drive than the FWDs with a 10% higher 5th (difference is still 8% lower)... thus FWDS can possibly convert to an AWD 5th gear or 2wd converted AWD tranny to get taller gears and less rpms.

FWDS are much better for long trips, becasue of the incresed fuel economy and lower noise.

with an AWD you want at least a 225/45/r17 at the very smallest, and a 235/45/r17 is spot on in terms of tire diameter...

 

[larsenracing]

Just wondering does anyone have or know where i can get the 2nd and 3rd gear gear sets for a 2g gs-t 5 speed transmission. Also, i am still looking for a differential yet. please give me some advise i really miss my boost. This thing forced me into my 98 Honda civic ex work car and that thing is such a pooch. but i guess at least i have a second car to drive sense i blew up the differential in the dsm.

 

[SethA]

I would try:

http://www.shepracing.com/

and

http://www.mitsubishigraveyard.com/

Seth

 

[Majikterror]

www.teamrip.com

 

[99gst_racer]

So, does anybody have any experience with this gear? TRE does it for $300, and I know it's stronger that the OE gear.

Post your experience with it.

How does it affect your 60 ft times? What are the greatest benefits from it? Any help would be greatly appreciated.

 

[jtmcinder]

Most people say it hurts 60' times. Last I heard (i.e., before I was banned from NABR for being a liberal with a mouth), Shep was still running the stock first gear, not the taller one.

In contrast, at least one autocrosser (who doesn't do ProSolos) has said he loves the taller first, since it makes it easier to go back to first for turn-arounds.

- Jtoby