Toyota RAV4 Forums banner

1 - 20 of 28 Posts

·
Registered
Joined
·
28 Posts
Discussion Starter #1
Hello
i was driving today my RAV4 automatic in the sand. It is Great car but during uphill drivings it cannot ride and after some ride it cannot even spin wheels uphill.
Any one has an idea how to shorten first gear way more?

my automatic rev engine to 3000 rpm but wheels...
 

·
Registered
Joined
·
165 Posts
Smaller tires.

In North America the RAV came optioned with 235/60-16 tires. The vehicle came standard with 215/70-16s.

You could go smaller, like a 215/60-16, but tire options become scarce. Although Yokohama offers their great Geolander A/T G015 in this size. You also mentioned driving in sand, depending on how soft and deep these conditions are you obviously don't want to give up too much ground clearance. In this case if you already had 235/60s, going 215/60s would cost you 1 centimeter.

I replaced my 235/60s with 225/70 ATs and the acceleration, especially from a dead stop, was remarkably worsened. I've since made a lot of changes/modifications to gain that lost acceleration back, but mounting taller tires without a corresponding gear change is a performance killer.

 

·
Registered
Joined
·
28 Posts
Discussion Starter #4
I have 235/70 r16 tires and car is lifted.

Lowering pressure will not give me anything.

Because the problem with car is lack "gear reducer", little help will be much shorter 1 gear. Car in deep sand has not enough power on hydrokinetic clutch to effectively spin tires. That why I am thinking how to shorten first gear or even main gear. I have 3 door version which is quite light - 1320 kg - and short so it is very good in terrain. Only disadvantage are gears....
 

·
Registered
Joined
·
165 Posts
. . . during uphill drivings it cannot ride and after some ride it cannot even spin wheels uphill . . . I have 235/70 r16 tires . . .
😆 Yep, that'll do it!

No low range transfer case, wide ratio gear spacing, inability to re-gear the differentials . . . this is the price we pay for running bigger tires. My modus operandi is to fit the tires that best get the job done, not the largest tires that will fit. If you watch the video below to the end, you'll see the Utes don't go anywhere on 35" tires that they can't go on 31's.

Going to a 5.7% smaller tire:
". . . seems as though the vehicles has picked up about 100 kw . . . effortlessly going through the soft sand . . . you want cheap horsepower, lower the size of your tires. That's a BIG difference."
 

·
Registered
Joined
·
165 Posts
Rereading your post I realized your problem is even worse than I thought, you maybe have the 1AZ-FE engine 😱 Holly gutless wonder Batman!

If reducing tire size just isn't an option either, the only action I think you can make is dramatically increase the 2.0 engine's power via forced induction, or, perform a 2AZ engine swap.

Members here have done the later and I think they're happy with the results (y)
 

·
Super Moderator
Joined
·
9,743 Posts
my automatic rev engine to 3000 rpm but wheels...
If the end of the sentence is "but the wheels don't spin" that indicated a slipping transmission or bad torque converter to me.
 

·
Registered
Joined
·
432 Posts
Automatic and manual RAV4.2 have almost the same final drive ratio (4.40 vs 4.56). But sadly for you the automatic 1st gear is very close to the manual 2nd gear.
 

·
Registered
Joined
·
28 Posts
Discussion Starter #9
Automatic and manual RAV4.2 have almost the same final drive ratio (4.40 vs 4.56). But sadly for you the automatic 1st gear is very close to the manual 2nd gear.
this is very bad information, slowly I am starting thinking about Suzuki Vitara...

I was talking with polish company which is able to create gears to transfer case. With automatic transmission this is the only option. the question is how much of free space there is for bigger main wheel. I know that KAAZ made something like that for Celica.
bigger wheel and smaller shaft.
 

·
Registered
Joined
·
165 Posts
But 1st gear is the problem. With the transmissions 3.938 gear ratio and 2.929 at the diffs, he's got an effective final drive of 11.1. A 235/60-16 tire has about an 11.85 final ratio.
 

·
Registered
Joined
·
432 Posts
With the transmissions 3.938 gear ratio and 2.929 at the diffs...
Where did you take the 3.938 number? I did not see it anywhere.... so maybe I found the wrong numbers myself.

You never calculate the rear differential ratio with AWD/4WD Toyota that have a transversal motor/transmission.. The 2.9 rear diff ratio gives 1:1 with the final drive ratio IN the transmission... whatever this final drive ratio is.
 

·
Registered
Joined
·
165 Posts
Two sources I've used are:

These are the four-speed autos of course. I actually don't see a single five-speed manual with a lower 1st gear in Toyota's inventory. The U140F actually has a lower 1st gear, but the E's have a taller overdrive and closer ratio spacing.

I hadn't thought of that about the transverse engine/transmission :unsure: but the end result is the same. It's artificially raising the final drive equivalent because the larger tires increase the moment arm of the driven wheels to the crankshaft.

The numbers I mentioned above are extrapolated from the RAV's final ratio in 1st gear only, with a mathematical comparison between the two size tires. Not the actual gear reduction.
 

·
Registered
Joined
·
432 Posts
Sorry Bartlomiej;

I made a mistake and gave you wrong information. I don't know why I used the A540H automatic transmission.... so forget the 2.81 first gear ratio, and 4.404 final drive ratio. The real numbers are 3.938 for the 1st gear and 3.08 for the final drive.
 

·
Registered
Joined
·
432 Posts
05RAV; which gear and tires calculator do you use? Thanks
 

·
Registered
Joined
·
165 Posts
Well in regards to this thread I just used my fingers. But for side by side calculations I like tiresize.com because they provide you a lot of tools and visual depictions like this one: Tire Size Comparison
 

·
Registered
Joined
·
28 Posts
Discussion Starter #17
Sorry Bartlomiej;

I made a mistake and gave you wrong information. I don't know why I used the A540H automatic transmission.... so forget the 2.81 first gear ratio, and 4.404 final drive ratio. The real numbers are 3.938 for the 1st gear and 3.08 for the final drive.
No worries ;)
From what i remember you have changed transfer case. Do you have still the old one?
For me it is interesting how much of free space there is for new bigger wheel to change final ratio. Also is there any space for small shaft which is connected with this bigger gear.
 

·
Super Moderator
Joined
·
9,743 Posts
I'm still surprised you can floor the gas pedal, rev the engine to 3000 rpm and have the tires not move w/o something being wrong with the transmission or TC.
 

·
Registered
Joined
·
28 Posts
Discussion Starter #19

·
Registered
Joined
·
432 Posts
From what i remember you have changed transfer case. Do you have still the old one?
For me it is interesting how much of free space there is for new bigger wheel to change final ratio. Also is there any space for small shaft which is connected with this bigger gear.
I'm not sure to understand exactly what you want to do. :unsure: What do you means by ''bigger wheel'' and ''small shafts''... can you explain it with different words please?

Yes I still have the RAV4.2 t-case.... but it's still on my RAV for the moment. During winter I'm using the RAV4.2 transmission and t-case, and during summer I use the RAV4.1 transmission and t-case.
 
1 - 20 of 28 Posts
Top