When to regear?

[caprihorse]

Also I dont want the power, I'm just looking for more torque.

You should understand a bit a physics and calculations when you are talking about torque and HP... there is no difference, it's just matter of mathematical formula. Read more here - http://www.almost4x4.com/vb/showthread. ... Horsepower

[funindubai]

Caprihorse, I raced in Touring Cars for a few years at national level, and yes there is a BIG difference on how to tune a vehicle. You can tune for max power or you could tune for a flat torque curve. Very different tuning techniques, bro. With max power, the shape of the torque curve is different. Happy to share this experience...

[Paul]

Hi guys

I know what you mean.

On my Jeep, the new 3,6L engine is quite 'peaky', anything less than 3000 to 3500 engine rpm has no performance, torque, power, grunt, go.... Or whatever you want to call it!!!!!!

For those of you who would like to read more about re gearing, look here:

http://www.pirate4x4.com/tech/billavista/Gear_Setup/

It is for a Dana 60 axle, but the principles are the same on most solid axles. They have shims in different places, different ways of setting bearing Pre-load, etc, etc

Regards
Paul

[caprihorse]

Hi guys

I know what you mean.

On my Jeep, the new 3,6L engine is quite 'peaky', anything less than 3000 to 3500 engine rpm has no performance, torque, power, grunt, go.... Or whatever you want to call it!!!!!!

For those of you who would like to read more about re gearing, look here:

http://www.pirate4x4.com/tech/billavista/Gear_Setup/

It is for a Dana 60 axle, but the principles are the same on most solid axles. They have shims in different places, different ways of setting bearing Pre-load, etc, etc

Regards
Paul

It's a great article and brings lots of light in this mystery :045:

[Paul]

Hi guys

For those who don't like reading:

http://m.youtube.com/#/watch?v=dAqAqODm ... AqAqODmcj4

Regards
Paul

[Ducati]

car that has bigger tyres as 33 tires, as the tyre size change the ratio on the whole car has changed and in particular gear ratio,
now the car with the big tyres lost it is standard drivability with the optimum power , speed , and range . to return to stander you have to re-gear , and it is mean change the gear in front and rear.
for the FJ you can check the net
the graph for tyres , gear ratio and rang is attached please check

http://www.alloyusa.com/gear-ratio-calculator

http://www.jeep4x4center.com/jeep-tires ... -chart.htm

http://www.offroaders.com/tech/gear-ratio-chart.htm

[Paul]

Hi

These 3 links are for a 1:1 gearbox ratio and at 65 mph. They are useful, but generic.
They are not giving any info for any of the other gears.
In the sand, rpm @ 65mph in 5th gear is not something I care about.
I have created a graph for my Jeep, for all the gears. Will try attach it.

regards
Paul

[sami]

Hi,
So I have a manual wrangler 2012 with 3.73 axle ratios and 35” BFG a/t tires. I am mostly happy with my current setup. But I too am considering regearing to 4.56 for one main reason which is the lack of torque at low rpms when in 1^st gear 4H. When going up dunes generally I feel there is still sufficient power but when slowing down near the top of the dune to take a look before descending the engine begins to lug (the sound before the car stalls)because the rpms are dropping too low. Also when stopped in some flat soft sand areas where the tire is sunk in the sand but not stuck requires excessive clutch work again because of insufficient torque at low rpms. Also situations that require slow controlled driving like technical dunes also are sometimes a struggle which leave me either feathering the clutch or sometimes just revving a bit and dumping the clutch to get out.

You should know that regearing from 3.91(stock fj 32) to 4.56(33”) doesn’t get you geared like stock it actually leaves you over geared meaning your highway mileage will probably suffer. Now I haven’t done the calculations for your case but in my case If I go 4.56 I will also be overgeared even though in my case the tire is around 4” larger than stock vs. you having 1” more. I am not saying it is a bad thing to be over geared it might turn out to be great off road, just saying I don’t think it will be like stock.

[Paul]

Hi Sami

Reading your post was like reading my mind.
I have the same car with 33" tires and 3.21 axle ratio, so we are quite similar, rpm wise.

The big difference with a FJ is it has much more torque at low rpm and its gears are good to start with.
On the JK, even with stock tires, 6th is too low rpm @ 120km/h.

Regards
Paul

[sami]

Hi Paul

I'm not surprise practically we are in the same situation and i too am not too sure about re-gearing. If only they sold rubicons here i might not be suffering from this issue as much. you're completely right about the 6th gear in the 2012 not much use even stock.

yes you're right about the FJ too. Your stock setup in 4H leaves you with 4.46(jk 1st gear) x 3.21(axle ratio)= 14.317 while FJ not only has better torque output at lower revs but also better gears 4.17(fj 1st gear) x 3.91(axle ratio)= 16.3

But at the end of the day I haven had any personal experience with the fj so i cant really say anything definitive also its about personal preference and it should in theory make it easier to get some extra torque when needed.