diff ratio help

[Sickbananas]

Hi Guys,

my diff is shot so I have decided to upgrade to either a Wavetrac (although nobody has stock) or Harrop Eaton truetrac. I am yet to fit my Whipple 2.9 blower (standard pulley size for now), with stock internals, complete valve train upgrade, BTR blower cam, arp bolts, fuel system upgrade etc. I have no idea on what power I will make, but it should be plenty.

My VE UTE is a manual and I have 285/35/R20 Toyo Semi slicks at the back. What ratio diff gears will be best suited for my application?

I'm not after top end speed and drive 100% on the road with the odd 1/4 mile drag. I just want to choose a ratio that would best suit the power as I have the opportunity to change it to whatever I decide on now.

thanks,
Rob

 

[losh1971]

What's in it now, 3.45?

 

[Shen Long]

3.73 or 3.9

anything taller & you’ll probably regret it

 

[Sickbananas]

I

What's in it now, 3.45?

Its a 3.7 (from a V6 VE I think), that the previous owner swopped out

 

[07GTS]

its the torque u have to worry about with the PD blowers, going too high in diff will make traction even harder to get, were as the sluggish OE ratio is bad n/a but the blower torque really helps them out, id prob pick an in the middle ratio if u want to bit more poke or keep it lowish if u want more usable gears

 

[losh1971]

I

Its a 3.7 (from a V6 VE I think), that the previous owner swopped out

If you have factory 3.7s they are worth a bit SH.

 

[Sickbananas]

its the torque u have to worry about with the PD blowers, going too high in diff will make traction even harder to get, were as the sluggish OE ratio is bad n/a but the blower torque really helps them out, id prob pick an in the middle ratio if u want to bit more poke or keep it lowish if u want more usable gears

yes 100% makes sense, do I just stick with a standard ratio of 3.45 then? or perhaps a 3.27 ratio or lower?

 

[losh1971]

I have 3.9 on my NA and I reckon I could have even gone 4.1. I think most tend to stick around stock gears when boosting.

 

[losh1971]

3.45 would be my choice if I was boosted. If I still needed more traction I'd look at grippier tyres.

 

[losh1971]

If you're getting a diff built consider a Kaaz they will handle as much power and torque or more than a Harrop.