bentheswift

My tC has almost 65k miles on it now, so the warranty is up. The thing that has disappointed me about the car is that its highway mileage is mediocre at best. I like to keep track of how much my car is costing me, so I've kept a fuel mileage log since the car rolled off the lot: http://www.fuelly.com/driver/bdc/tc

I'm not that disappointed with a 29mpg average since new (given its 20/27mpg "ratings" from the EPA) but the most I can reliably get on the highway is 31 to 32mpg. On a couple of trips I've beat that and done as much as 34mpg, but that was sub-60mph trips on rural highways. On the interstate, at reasonable speeds, 32mpg is the most I can hope for, and that only on summer gas. Now, I enjoy the reasonably torquey motor and the short gears, but I also know that I've spent over $2,000 in gas this year JUST on this one car. I live outside of town and almost always drive on the highway, so a couple of extra mpg would save me, by my math, $100 to $150 per year at current gas prices. Gas isn't getting cheaper and I like this car, and want to keep it around.

The problem is the gear ratios, since an equivalent Camry was rated something like 4mpg higher on the highway, despite much more weight. The Camry 5-speed came with a 3.944 final drive as well as a .731 5th gear ratio, whereas the tC, in order to make it "sporty," was equipped with the 4.235 final drive and a .775 5th gear. Which combined, mean a bit over 12% higher revs in 5th gear. So at 65mph we're turning about 3,000 rpm, while a Camry is turning 2600. That ~400rpm doesn't seem like a lot, but is makes up most of the reason why the Camry is rated 4mpg higher on the highway.

My car is used for a regular 50-mile commute and has to be working all the time, so I don't want to swap this perfectly-working transmission out, nor do I want to split the case to swap the final drive. Plus, I can't argue that the short gears are a little fun (though first is pretty much useless). No reason to swap the final drive since 90% of the miles on this car are in 5th gear.

So, with a little help from old threads and some forum members (especially jimmyjun, tjkass, and j3st3r) I think it's plausible to think that I can swap the 5th gear set without removing the transaxle or suspension. I jacked the car up last night to look around, and by removing the under-cover and the driver's side wheel well cover, I can get pretty good access to the transmission end cover. The frame rail might make it a little tricky to access the topmost bolts on the cover, but shouldn't affect getting the gears out. Regardless, if I find that I don't have good enough access in the car, I can abort the project after removing the cover, or I can unbolt an engine mount or two and see if that helps.

I priced out a set of the two .731 gears. From a local dealership that heavily discounts parts, I can get the two of them new for $208. (5th driven gear: 33428‑42020; 5th gear: 33336‑42020.) I would expect to spend at least that much on a used transaxle, so I think I will go this route and know that I have new parts. There is also a big 30mm nut on the output shaft that I would rather replace than re-use (since it is staked to the keyway in the shaft) and I believe that is 90179‑20012, about $5.

Here are some questions that I have for anyone who thinks they could help:
1. Do I need an impact wrench to remove the output shaft nut? I would assume that, if the trans is still in the car, I could hold the brakes and the shaft would not be able to spin (since the output shaft is locked to the wheels regardless of whether it's in gear). But I'm not sure if that's correct.
2. Do I need a gear puller to remove the two 5th gears after I've removed the above nut? I'd assume so but never done this before.
3. Is there anything I need to make sure not to do while I have the trans cover off? Not sure if there's anything I can seriously mess up while I'm in there, that might require removing the transaxle to fix. Like I said, never done this before.

So, if you think I'm crazy for trying to spend $215 and a weekend in the garage on 1-3 highway mpg, as well as a fun experience, this project probably isn't for you!

Any insight or advice is appreciated. Especially with regards to the ease of accessing the transmission in the car. I've done a lot of DIY wrenching, but never opened up a transmission that I was going to use again. Thanks for reading.

Refer to:
https://www.scionlife.com/forums/sho...d.php?t=183344
https://www.scionlife.com/forums/sho...d.php?t=183553

thendawg

iTrader: (2)

You can swap 5th without pulling the trans. Takes about 30min-hr. The only prob, the 5th gear alone wont help you that much - if you do the gear calulations, at 70, youll only drop about 180rpm. The big difference is in the diff (final drive). The tc is close to 4.20, whereas the Camry trans is aroudn 3.9x. With the actual Camry trans (E351) youll be about 400rpm lower at 70, which is where the big difference is. If its worth it for you, go ahead, just saying its not going to make a night and day difference.

criminaltc

You buy a car, you are liable for all expenditures that are involved i.e. gas, oil, maintenance in general. Not sure if you were aware of that, just wanted to try and help.

BleackOne

easy fix*. turbo it. FACT.

aryana159

I replaced my 5th gear and synchro cause mine was all shredded where it would go in so it kept poping out of gear.

The way I did it not saying is correct but this is how I did it.

Step 1: jack car up

Step 2: remove drivers side front wheel

Step 3: remove fender liner (I already took mine out so I was good here)

Step 4: Locate the transmission cover (the black metal case where 5th gear and synchro is located)

Step 5: remove the cover few bolt hold it in place (may need to youse a flat head to pry it off)

Step 6: locate the 5th gear and syncro as your going to need to remove both to remove gear

Step 7: the is a bolt that goes in synchro remove the bolt Amd pull the synchro up but becarful there is a sleeve that will come up with it and ther is some weired way the Litle metal clips go back in. You will see what I'm talking about once you remove it.

Step 8: this is where it gets tuff you need a specialty tool to remove 5th gear since I didnt have the tool and none of the auto stores had the tool I bootled my own. You will notice 3 threaded holes on the gear The bolt you removed for the case will thread in or atleast I did for me. I threaded them in and housed a pulley pulled plus alot of messing with it to remove it.( it was a pain in the ___ )

Step 9: replace 5th gear sleeve and synchro.

Step 10: make sure to clean the area where the cover will mount from it's old sealent and do the same to the cover I used a razor blade.

Step 11: reinstall the cover housing some rtv red is what I used to make sure that it would seal properly.

Step 12: reinstall fender liner and wheel and hope it works!!!

That's how I did it hope it helps I'm not a professional by any means when it comes to transmission.

There is actual clearence that is supose to be measuredd which I did not do at all after installed I moved in and out of gear looked like it worked I installed Amd hoped for the best.

bentheswift

Wow, that is much more feedback than I thought I would get!! Thanks all!

Thendawg, you're correct that I will only be getting about 45% of the rpm benefit that swapping the Camry trans would give me. But, it's better than nothing, it's cheap, and it's about one tenth of the effort that replacing the trans would require. If I can squeeze out even an extra 1 mpg it will pay itself off in a couple of years and I'll be the wiser for DIYing. In the past 12 months I've spent $2200 in gas for this car at 28.9mpg average. Averaging one mpg better would have saved my $75 this year. So at that rate it would take almost 3 years... plus the decreased wear and tear on the motor... and I plan on keeping this car for a long time.

In fact, maybe I'll hunt around the local junkyards for a Camry trans and see if I can get it for less than $200.

aryana, thanks for the help! I may send you a private message if I find that I need some more specific help.

criminaltc, I can't say that I understand what exactly you were trying to get across.

thendawg

iTrader: (2)

I can sell you the 5th gears off a camry trans if you want them. I could do like $30 shipped. Youll just need a new stake nut for the output shaft. Send me a pm if youre interested.

aryana159

Yes I can vouch for the dawg good stuff from him and he also knows his stuff way more then me.

K0rupt

Is it worth doing for boosted cars to hit higher mphs?
Hows the tq curve with it in?

aryana159

Yes it's worth it to me I can go 140 in 4th where before I could only do 110 lol I'm loving it.


If you know hondas at all are transmissions are kinda like a Gsr transmssion and the camery is like the Ls transmissions so the longer gears help for turbo cars I'm sure torque falls a Litle but it will be ok.

+ better gas miles ftmfw I got 30mpg on the hwy with 1000cc injectors can't complain And my tubes off a bit need to get retuned asap

Vlad1024

OP is talking about swapping 5th only. Because final drive will be unaffected the improvement will be marginal at best. More power to you for doing it but don't expect miracles.

bentheswift

No miracles expected. Just trying to make my grocery-getter a little bit better at getting the groceries.

I went through j3st3r's excellent trans assy./disassy. threads yesterday, making notes for every step as well as a tool list. As long as I haven't royally overlooked something, it should be a fairly easy afternoon job.

The critical item that I'm not sure about is while I have the fifth gears out, how I should lock the transaxle. I'm not sure if I should put it in any gear other than fifth, or just have someone hold the brake pedal, or if it even matters. Seems like I shouldn't have trouble removing the 30mm staked nut on the output shaft, since it is locked to the diff, which I can hold by having someone stand on the brakes. And it's only 90 ft-lbs so I don't think I'll need an impact. Can anyone give me any input on that problem?

bentheswift

I haven't been able to get in touch with thendawg. If anyone has a Camry or xB trans that they can get 5th gear out of, would you PM me? Or thendawg, if you do read this, I'll pay you double what you asked. I'm really hoping to get some gears by Christmas so I can get it done while I don't need the car for the commute. And even $60 is a lot cheaper than $200.

Ryan99FL

Sooo... what was the outcome of this little project?

engifineer

If you gain 2mpg on average (doubtful, but maybe), assuming $3.50/gal and 12,000 miles a year, it will save you around $90 a year in gas. If it costs you about $250 total, then it will take you about 2.75 years to make back what you spent from gas savings. So you really wont save anything for the first few years really. So, it wont really help you much at all. If you just want to do it for fun, that is another story.

ESEMRFOZZ13

and as the good old ace man would say, how much is your time really worth.

bentheswift

Thendawg is going to supply me a gear set but hasn't been able to get time to tear his Camry box apart. I decided against buying new for obvious reasons.

buzzsawlouie

As a recent xb buyer, what's the outcome of this project? Was it ever completed? Is is what you expected? Was it worth it?

bentheswift

I never was able to get a hold of a used 5th gear set and didn't want to pony up the cash for new ones.

I am reconsidering the project though, but still getting through some odd transmission problems. See my other thread in the tc owners lounge.

https://www.scionlife.com/forums/sci...h-gear-229596/

bentheswift

But, the xB has the same gear ratios and final drive as the camry... so you already have the 5th gear that I would like to swap.