Final Drive Ratio of Camry Manual transmission and of Auto transmission.

[Jim.]

I have just acquired a nice old 93 Camry wagon that has only done 125,00klms and is in really good condition. I had an auto trans one before that.

This manual trans car drives like a sports car in comparison; the auto one was sluggish and underpowered on hilly terrain.

The auto trans car ran at around 2200 rpm when in overdrive and travelling at 100klms per hour.

The manual trans car runs at around 2800 - 2900 rpm when in 5th gear and at the same speed.

This leads me to conclude that this car is undergeared; it is excellent for city and suburban driving due to this, but a bit short on "legs" for highway travelling.

I would like to find out the final drive ratio for both these vehicles if possible. This is only academic as I won't be going to the trouble of changing the crown wheel and pinion ratios, (if that was possible.)

Question:

Can anyone inform me of where to find these specifications please?

Also, does my experience above match anyone else's observations?

[jeffy]

Yes,

when i had the auto tranny - it was doing 2400 rpm @ 100kph

manuel tranny does 2900 @ 100kph

[Hiro]

Autos can afford to be geared taller because they have the ability to slip the torque converter at lower speeds to boost torque.

Plenty of info online about Toyota gear ratios, the manual is probably an S53 and the auto something like an A140E

[Jim.]

Thanks for the replies Jeffy and Hiro.

It seems that I have nothing unusual here.

It does appear to be a bit counterintuitive to my mind, but I don't really know.

[TIDYWAZZA]

Are your tyres and or wheels original spec. sizes ? This can also be a factor in engine revs.

[Jim.]

Yes Warren, they are standard.

But it does remind me that if I fitted larger wheels/tyres, that would raise the final drive ratio.

I don't know what tyres and/or wheels would be in that category, but it's worth considering.

[trentmeyer23]

As long as the overall diameter is the same, you won't have issues with ratios.

[TIDYWAZZA]

I include this link, it is remarkably handy for calculations of tyre/wheel size changes.

http://www.carbibles.com/tyre_bible_pg4.html

[Jim.]

Can someone tell me of a stock 15 inch wheel that will fit the Camry?

I have skimmed through the link above, thanks Warren. So I am aware of the caveats around changing wheel and tyre sizes. I'm interested in giving it a go. It would also raise the front end slightly.

This brings up an interesting theroetical comparison:

1. Is it likely to result in longer engine life and better economy to lower the final drive ratio? After all, both the auto model and manual model have the same 5SFE engine, yet the manual one runs at considerably higher rpm for a given speed - both in top gear.

2. Is there a down side (apart from changing the odometer/speedometer) to doing such a modification? The gearbox has plenty of options in the lower gears for driving around town. A lower final drive ratio and it would make the car run at a lower rpm at highway speed in top gear. As it is now in standard form, there is plenty of available torque and power at highway speed.

Or is the concept of "overdrive" just a way of adding another gear?

It might be helpful to view the torque and power curves for this model vehicle.

Edited January 12, 2015 by Jim.

[Hiro]

Can someone tell me of a stock 15 inch wheel that will fit the Camry?

I have skimmed through the link above, thanks Warren. So I am aware of the caveats around changing wheel and tyre sizes. I'm interested in giving it a go. It would also raise the front end slightly.

This brings up an interesting theroetical comparison:

1. Is it likely to result in longer engine life and better economy to lower the final drive ratio? After all, both the auto model and manual model have the same 5SFE engine, yet the manual one runs at considerably higher rpm for a given speed - both in top gear.

2. Is there a down side (apart from changing the odometer/speedometer) to doing such a modification? The gearbox has plenty of options in the lower gears for driving around town. A lower final drive ratio and it would make the car run at a lower rpm at highway speed in top gear. As it is now in standard form, there is plenty of available torque and power at highway speed.

Or is the concept of "overdrive" just a way of adding another gear?

It might be helpful to view the torque and power curves for this model vehicle.

There's no point going down the oversize tyre route to increase your final drive ratio, since to get any meaningful drop in RPM requires a significantly bigger tyre - say from 3000rpm down to 2700rpm, a 10% drop, you would need to go from the stock 185/75/R14 to a 235/75/R14, which is a HUUUUGE tyre for a 14x5.5" rim. You'll end up looking like a jacked-up 4x4 with 35" BF Goodrichs before you start seeing meaningful RPM decrease, by which stage the increase in rolling resistance and inertia will cancel out any fuel savings from the lower rpm. Not to mention your speedo being out by ~10km/h at cruising speed (and in the wrong way, so unless you pay attention you'll be going 10+ over the limit all the time). Ohh, and did I mention it is illegal as well unless engineered(in NSW you're allowed up to a 7% change in overall diameter from the tyre placard)?

Note that even though the auto has a lower cruising RPM, it still gets worse fuel economy on the highway, indicating the drain on power that most 80s/90s autos have. I've been in a manual 5SFE-powered Camry up and down the F3 freeway more times than I care to remember (used to go on road-trips with my parents just about every second weekend as a kid), and invariably you'd have to kick back to 4th for any decent hill, and that's with stock gearing and stock tyre size. Even with only me in the SXV20, the hills either side of the Mooney Mooney bridge require a run-up to be able to stay in 5th.

"Overdrive" stopped meaning a separate overdriven transfer unit back in the 70s and just refers to top gear being driven at <1:1. The only reason autos of the 70s-90s still had the O/D button was to stop the transmission shifting into too high a gear when cold or when towing - most 4-speed autos don't have an O/D button any more, and 5/6/7-speed autos will have more than one gear <1:1.

As for engine life - it's a Toyota. You get 300,000km+ out of them completely stock-standard, so why worry about increasing longevity?

And the perfect 15" tyre size for you would be 205/65/R15 - that's what the Vienta came with.

[Jim.]

Well, you have summed up the situation very thoroughly Hiro, thanks.

The automatic car that I have retired and am now wrecking has done 410,000 klms and was still only burning about 1 ltr of oil between changes. I only took it off the road due to auto trans problems, for the second time. It was not worth the expense of reconditioning it again.

It seemed a pity apart from that.

Great engines. I did maintain it well and drove it moderately at all times.

I drive like the "little old man" that I am!

Just one small quibble in what you have written; changing down from fifth to fourth while going up a slight hill seems perfectly normal to me, but that is just my subjective experience and perhaps limited understanding.

Conclusion:

No larger wheels or tyres for this car! Anyway, I do less and less long trips now days anyway. Mostly just short/medium commute trips.

[Hiro]

Just one small quibble in what you have written; changing down from fifth to fourth while going up a slight hill seems perfectly normal to me

Was more implying that you have to do it with the current gearing, a change to the final drive ratio will make it worse (and will make every hill worse)

[TIDYWAZZA]

Perhaps this link will help. At least you know what rim will fit then ask about the diameter of the rims you find. Years ago in my old Hiace i went from 14' to 15" Fairlane rims and lowered my engine revs considerably. still had heaps of torque. I cannot recall the tyre sizes.

http://www.wheelfitment.eu/car/Toyota/Camry%20(1992%20-%202001)/

[Jim.]

Thanks for that link Warren.

I will study it later.