Toyota Tercel taller gearing (Corolla too)

[H-Man]

What ratio is that A244 diff? I have a C52 I think and I'm doing 3000 rpm at 62 MPH (according to GPS) on tires that are 815 revs/mile, giving me a final drive of 4.3 if I have a .815 5th gear.

How are you torquing the bolts? I know some of the bolts require a $300 torque wrench to set the torque correctly.


I wish I could get my hands on a transmission with a 3.7 final drive, a 3.545 1st, and a .725 5th gear. It would allow me to run 840 rev/mile tires (175/65/R15 LRR tires + rims are cheaper than going to 14" LRR tires) and have an easy time on hills but still be able to keep the revs down on the freeway.

[Daox]

Originally Posted by cosmick

Curious what reference you're using, if any, to indicate you're not dropping the RPM more than ideal? Or is this, like me, just trying to get a new baseline to work from?

Its definitely not a total shot in the dark. Here is what I have.

A while back I made this dyno chart with a g-tech pro. From this chart I know I have ~17 hp at WOT at 1500 rpm.



Now, using the hand dandy ecomodder aero & rolling resistance calculator, I know that I need about 7 horsepower to keep me going on a flat road at 45 mph.

Tercel aero & RR calculator




So, theoretically, I should have about 10 hp left over. Sounds like enough to me. Originally, at 2100 rpm I'd have had 26 horsepower available.

[cosmick]

If it'll stay in closed loop at the required throttle position, then I guess you'll have good results to share soon. Thanks

[Daox]

Yep, thats the thought. If it goes into open loop... eh I'll figure it out then.

[Daox]

Originally Posted by H-Man

What ratio is that A244 diff? I have a C52 I think and I'm doing 3000 rpm at 62 MPH (according to GPS) on tires that are 815 revs/mile, giving me a final drive of 4.3 if I have a .815 5th gear.

How are you torquing the bolts? I know some of the bolts require a $300 torque wrench to set the torque correctly.


I wish I could get my hands on a transmission with a 3.7 final drive, a 3.545 1st, and a .725 5th gear. It would allow me to run 840 rev/mile tires (175/65/R15 LRR tires + rims are cheaper than going to 14" LRR tires) and have an easy time on hills but still be able to keep the revs down on the freeway.

The differential ratio of the A244 is 2.821, quite low compared to what I've seen in almost any Toyota transmission. I might have to downshift for bigger hills, we'll see.

I have a torque wrench. I'm not sure why you'd need some crazy expensive torque wrench to torque down the diff gear bolts or bellhousing bolts. Those are the only bolts that I need to change. I don't think they're anything special. What bolts are you talking about?

[Daox]

Here are the gear ratios I know of the C5x and C6x (6 speed) transmissions. As mentioned, I have a C52. Mine is from the 7A-FE, so it has a taller 1st gear than the 4A-FE C52, and lower final drive than the 4A-GE. All have a .815 5th gear though, and the final drive will be replaced with the A244's gearing.

If that is not enough, I'll could always try to get my hands on a C59 which has a .725 5th gear ratio. That would bring my rpms down to an almost ridiculous 1360 rpm at 45 mph, or 1960 @ 65 mph. I'm thinking that that is a bit too low though. However, the C65 would probably be a perfect match as it has a .815 and .725 gear. But, those typically cost a ton and are pretty rare.

[cosmick]

Can you combine the 3.545:1 first with the 0.725:1 top? That's where I'd go next.

[Gasoline Fumes]

Originally Posted by Daox

1960 @ 65 mph. I'm thinking that that is a bit too low

That's about what my Wagon does with the HF gearbox and 185/65-14 tires. 2.954 final drive and a 0.694 5th gear. It's awesome on the highway!

[H-Man]

I know that the euro ae101 had the automatic model with 1.6l engine as a 4 speed automatic that did 2200 RPM@60MPH. Toyota compacts don't get enough love on this site, I can pick up a corolla cheaper than a civic and it is unlikely that the car has been owned by a ricer.

[serialk11r]

Originally Posted by Daox

If that is not enough, I'll could always try to get my hands on a C59 which has a .725 5th gear ratio. That would bring my rpms down to an almost ridiculous 1360 rpm at 45 mph, or 1960 @ 65 mph. I'm thinking that that is a bit too low though. However, the C65 would probably be a perfect match as it has a .815 and .725 gear. But, those typically cost a ton and are pretty rare.

They're not rare, but they aren't junkyard parts you'll be able to find for cheap. Monkeywrenchracing carries the European C6x with 3.9 final drive and 0.725 6th, which brings cruising rpm down to ~2400rpm at 60mph, and they run 1600 for a used one. There's a guy who imports them from the UK for 1200 or so on Spyderchat (but you'll have to convert the shift linkage back to the usual FWD one).

If I were to replace my C56 right now it would be with a 4.5 FD C60 maybe with a slightly taller tire, or maybe not. I have to cope with hilly city driving so short 1st gear is really useful. For a highway cruiser, 3.9 FD + oversized tire is the way to go.

I have no idea if the 3.7 would go into the 5 speed gearboxes but if you have the ability to open them up and do it that would be worth a shot. I have never heard of a 3.7 C56, I thought they only come in 3.9 and 4.3 flavors. The 4.5 and those 2 are interchangeable.