Thread: gearing for 34"?

Originally Posted by Steve223

Dave Ashcrofts response in regards to strength of different pinions

Q: Can you clarify how much weaker a 4.75 pinion is in comparison to a 4.12 or 4.37?

A: We have had failures of the 4.75 ratio from our old manufacturer but since we changed about 2 years ago I don't think we have had any fail, so very little difference if any,

There is a difference in strength due to the ratios, BUT you may never put that much stress through them (not like you're building a comp truck on 37's), obviously none in the last 2 years have been used harshly enough to break

Anyone know how I can calculate the difference between standard gearing and tyres and:

• 4.12 gears and 285/75R16 tyres
• 4.12 gears and 315/75R16 tyres
• 4.37 gears and 315/75R16 tyres

?

Originally Posted by twr7cx

Anyone know how I can calculate the difference between standard gearing and tyres and:

• 4.12:1 gears and 285/75R16 tyres
• 4.12:1 gears and 315/75R16 tyres
• 4.37:1 gears and 315/75R16 tyres

?

I found this calculator - Gear Ratio Calculator

According to it, if the standard tyre size is 235/70R16 with a standard diff ratio of 3.54:1, then:
285/75R16 tyres want a diff ratio of 4.01:1
315/75R16 tyres want a diff ratio of 4.23:1

So my 4.12:1 Ashcroft gears are in between. Should be fine being an auto upsizing to the 315/75R16 tyres.

so have my issues sorted, re geared diffs to 4.3.7, put heavy duty torque converter it as well and car moves much better now. further moods front Ashcroft air locker, rear pegged AC air locker and 30% reduction Maxi Drive gears in transfer case

Originally Posted by Steve223

so have my issues sorted, re geared diffs to 4.3.7, put heavy duty torque converter it as well and car moves much better now. further moods front Ashcroft air locker, rear pegged AC air locker and 30% reduction Maxi Drive gears in transfer case

How have you found the new torque converter? Does it drive better? And where did you get it from? I'm thinking of doing mine. Any info would be great.
Thanks
Chris

Originally Posted by Steve223

saw on the weekend as Gees Arm South a couple of motorbike riders tearing up the last exit steps like there was no tomorrow ... all depends on how you drive

Being on two wheels you don't have the stability and balance as a 4WD to go slow all the time - the engines momentum is a significant factor in the balance of the bike. Also being only a couple hundred kgs with skinny tyres they do far less damage to the track when wheel spinning than if a 4WD was.

Originally Posted by SPROVER

How have you found the new torque converter? Does it drive better? And where did you get it from? I'm thinking of doing mine. Any info would be great.

Chris, there are heaps of threads on the Ashcroft HD torque converter if you have a look. But to summarise they are great and worth the expense and efforts.