Toyota Tercel taller gearing (Corolla too)

[cosmick]

I know you have slightly less drag than an '80s Trans Am, but those need 15 HP to go 50 MPH, so how can you figure 7 HP? What about your power steering pump, A/C compressor, and alternator? If each of those eat 5 HP, then you'd be toast, right?

[Daox]

Excellent point, I hadn't thought of that! You're right, I will need more than 7hp to go down the road at 45 mph in stock form. The accessories will add additional load on the engine, and so will the drivetrain losses. For others thinking about regearing, you should definitely take this into consideration.

Thankfully, the only loads not considered in my calculations are the oil pump, and transmission loses. I have no power steering on the Tercel. I don't have A/C either. The car didn't come with either as its the base model. I'm also planning an alternator delete, and an electric water pump. Add in a few aeromods, and I think it should all even out, even perhaps come back under 7 hp? In any case, I think I should have adequate power.

Thanks for pointing that out.

[cosmick]

About the electric water pump, when I pondered that, it seems to me it isn't worth the cost. And what the engine's oil pump uses is included in what the engine is putting out at whatever combination of throttle position and RPM.
Does this make us shadetree scientists?

[Daox]

Yep, the cost is the main thing with the electric water pump. That is why I came up with this:

http://ecomodder.com/forum/showthrea...eap-29896.html

[cosmick]

Then all you need is a generator mounted to a rear wheel, plus some way to disable it when not decelerating

[Daox]

Originally Posted by H-Man

http://bgbonline.celicatech.com/6g/t...05%20speed.pdf
The C52 gearbox rebuild
http://discodan.org/gfx/celica/servi.../chassis/a.pdf
Found those searching for 'C52 bearing preload'

My ae92 FSM outlines a similar procedure I think. For torquing, you need an in*lb torque wrench or maybe a spring scale and a wrench with a hole drilled in the handle an inch away from the center of the box end.

I finally read up on this. You need a tool to spin the differential and find the 'starting torque'. I'll quote the service manual in the link you have above:

Using Differential Preload Adapter (09564-32011) and an INCH-lb. torque wrench, measure differential side bearing starting torque. See Fig. 15 . Starting torque should be 7-14 INCH lbs. (.8-1.6 N.m) for new bearing and 4-9 INCH lbs. (.5-1.0 N.m) for used bearing. If preload is incorrect, remove transmission case side bearing outer race, and select new adjusting shim.

When I googled that part number, I found out its really nothing fancy. Looks like something you could pretty easily fab up with some scrap metal. Here is what it is:





With that tool, you stick it in the trans and use your torque wrench to find out at what torque it starts to spin. Based on that torque, you need to adjust the shims that preload the differential's bearings.





So, it looks like I'd have to procure an in-lb torque wrench (checked sears.com and they're ~$135), or figure out a lever + weight like the guy in the other link you posted did. Either way, it shouldn't be a show stopper by any means. Thanks for posting that info though!

[H-Man]

Any updates?

[Jooseppi Luna]

Since I've seen them mentioned here, I thought I should throw in that the C6X and C5X differentials do not interchange with each other... IIRC, it's a difference in output shafts.

[Daox]

Sorry, no updates. Too busy with other projects.

[Techie007]

It has been quite a few years—any further pursuit of this project or any dealbreakers discovered?

I am seriously looking into regearing the silly C59 transmission on a 2008 Corolla with the goal of gaining another 3-7 mpg, having evenly spaced gears that finally align with US speed limits, and having a 5th gear that actually does something instead of being there just for show (4th is almost on top of 5th in the C59; it comes with gear ratios of 3.166, 1.904, 1.310, 0.885, 0.725 and a ridiculously tall final drive of 3.941). As it is now, 3rd gear is optimal for cruising at 19mph, 4th gear for 30mph, and 5th is perfect for 35mph—if I'm driving through an urban area at 35mph, it's 5th gear all the way, 1400-1500 RPM, almost never have to downshift. But if I'm trying to do 25mph, 4th lugs the engine (1200 RPM) if there's any incline/acceleration needed, and 3rd revvs the engine (1800 RPM), giving so much power that a little tap of the accelerator jerks the car around and immediately takes the car over the speed limit. If I'm accelerating normally to highway speeds, I've usually shifted into 5th around 40mph already—and there are no gears past this! So imagine this silly transmission: 3rd gear is too slow for 25mph but good for taking continuous 90° turns, 4th gear is too fast for 25mph, and 5th gear is perfect for 35mph. Not good—there are no gears left over for highway speeds, and this engine screams down the freeway at 3000 RPM with no need to ever downshift even for aggressive passing. If there's ample visibility and room, I often pass in 55mph zones while staying in 5th gear (and climb most hills in 5th gear); and if it needs to be quick, I have to drop aggressively all the way down to 3rd and roar past at 4000-5000 RPM because 4th is almost as fast as 5th—once again, it would be really nice to have something in between 3rd and 4th because 4th is set at a "useless ratio" that's too fast to be good for anything except passing through to 5th (which disappoints and results in a jerk because it's "right there" compared to all the earlier shifts). And no, there's nothing "wrong" with this particular Corolla; I know a few people with similar manual Corollas (2005, 2006, 2007) and they behave exactly the same way. The optimizations I've done thus far have increased its average fuel economy from 35 to 40mpg; I'm hoping and expecting to have it pushing 45mpg on average with this mod. Even if it doesn't quite get there, I know future aero mods will have a greater impact if the engine has already been geared down.

The C53 (installed on Toyota's European 1.4L diesel Corolla and Yaris cars) is the only transmission I have found that they made with optimal and evenly spaced ratios (3.545, 1.904, 1.310, 0.969, 0.725), and it comes with a rather conservative final drive of 3.473. This is exactly what this American Corolla with a far larger engine should have shipped with IMHO—if they wanted to be conservative (instead of the fascist 3.941 final they used—it needlessly exalts the RPM of the engine far above that of the wheels, LOL). But this thread intrigued me particularly because while the C53 would make the car better overall (3rd would now be 22mph, 4th would stay at 30mph, and 5th would push to 40mph—just enough to solidly change the paradigm to 3rd for 25, 4th for 35, and 5th for highway speeds with the engine spinning on the fast side for all of them), it only improves the top gearing at 55mph from 2200 RPM to 1950 RPM, and now 3rd is too fast for continuous 90º turns and 2nd is still a bit slow to take its place. I have driven a similarly sized gas car with a 1.3L+CVT that could do 60-65mph on a level surface at 2000 RPM all day long (depending on temperatures and wind); this Corolla has a comparatively large 1.8L engine in it, and I'm not interested in a conservative optimization—if I'm going to spend the time and money to mod this transmission, I want the maximum (liberal, greenie) optimization!
This is where your proposed A244 final drive of 2.821 got my attention: This would drop 55mph all the way down to 1600 RPM, and we would need the C53's taller 1st and 4th gears as the C59's 1st and 4th gears would be way too short with this short of a final otherwise. If my estimates are correct, that would put the engine around 3/4 load at 55 on a level surface (with increasing headroom as the speeds increase to 70). In hilly terrain (especially with the A/C on), one would just stay in 4th at 55, which would put the engine at a comfortable 2100 RPM (remember the original 5th put it slightly higher at 2200 RPM). Furthermore, if more power was needed to climb a steep hill at 55, downshifting from 4th to 3rd would now be a comfortable and accessible 3000 from 2100 RPM instead of lurching all the way to 4000 from 2700 RPM. Admittedly, a 3.000 final would probably be optimal; the A244's 2.821 final is a bit on the short side overall, but it appears to be the best potentially available option at this point: 1st pushes from 8mph to 10, 2nd leaves skips over the original 13mph to 18mph (right under the original 3rd at 19, perfect for continuous 90º turns), 3rd jumps to 27mph (under what 4th used to be at 30, giving that elusive ratio for 25mph), 4th jumps to 37mph (just past the original 5th that was perfect for 35mph), and 5th jumps way ahead to 50mph finally giving the car a highway gear (and putting it a bit ahead of the 1.3L CVT car as it should be to maximize economy on a 1.8L engine). I figure at 1400 RPM that 9, 16, 25, 35, and 45mph would be optimal (and about what you'd get on the C53 with a 3.000 final), but the above really is quite close to those speeds and should be OK—the vehicle will just be a bit slower to accelerate and need to downshift sooner on an incline. Additionally, I have tested shifting straight from 1st to 3rd in the C59 to get a taste of what the wider gap between 1st and 2nd might feel like, and I can certainly live with it—especially knowing that the jump won't actually be quite that far (10-18mph instead of 8-19mph).

This brings me to my questions:
1. The general sentiment I have found here and elsewhere is that the gears are fully interchangeable within the entire C5x series gearboxes, but not between different series (e.g. C6x, C15x). Is this actually true, particularly when considering swapping gears/shafts between the C53 and C59? Obviously, for the gears to be compatible, the input and output shafts have to be spaced the same and be the same length. Is this the case?
2. Since I want all the gears of the C53 (and maybe even the final drive, if the A244 final can't be used for some reason), is there some reason why I couldn't simply pull the two gear shafts (with everything on them as-is) from a C53 and put them in the C59 instead of swapping all the gears over one by one? Will the existing C59 shifting linkage still all work with the C53 shafts/gears/synchros?
3. So the bolt pattern of the A244 final drive gear matches the C5x transmissions. Great—but that's just the start: To be able to use that gear, its mating small drive gear will need to be removed from the automatic transmission output gear shaft and swapped onto the C5x output gear shaft. Has anyone swapped the final gear's little mate between C5x transmissions (to prove that it can be done), and also verified that the output gear shaft size/spline shape is the same between the C5x transmissions and the A244 automatic transmission so its final gear's little mate can be brought over too? Is the "little" mating final gear part of the output gear shaft, or is it too just pressed on and removable like the rest of the gears?
4. So let's say we've got the mating final gears successfully moved over: The spacing between the output gear shaft and the differential shaft also have to be the same for those gears to successfully mate. Do we know this to be the case for sure between the C5x (particularly the C53) and A244?
5. Since the A244 final has a shorter ratio, I expect the final gear to be smaller, and its mate to be a bit bigger. So it's unlikely that there will be room issues on the X-axis with gears hitting the housing, but what about the Y-axis spacing? Are we sure that the A244 final gears will line up with each other vertically in a C59 housing and the final gear won't run into anything further down in the differential?
6. Will changing the final drive affect the speedometer/odometer readout on the C5x transmission? If so, I'll just have to program a MCU to act as a pulse multiplier to realign the pulse rate to what the dash cluster is expecting—but it would be nice to know beforehand. One thread I saw on this forum suggested that since the final drive gear itself spins the same speed in relation to the wheels, the speedometer would be unaffected. But if the sensor is on the output drive shaft in the C5x transmissions, the speedometer would read too low after reducing the final drive ratio.
7. I'm not too worried about sourcing a C53 transmission at the moment—it appears that they are readily available at B-parts.com for $500-900, although it would be nice (assuming all the above points are true) to be able to purchase just the gears/shafts instead of having to purchase and ship an entire transmission.

Any thoughts?