Diffs

[Peterj70]

Hi Guys & Gals,
Question: I have an 09 manual SS wagon.
It has got a full system, high flow cats, OTR intake & a maf tune..
I drive it everyday, and running on a tight budget. Has anyone had any success with shortening diff ratios?
I don't need to do 300kph, but a quick 0-200kph would be nice!!!

 

[ilusiv1]

I've read countless threads about diff ratios to run in VE's and everyone seems to be divided and I couldn't even get a definitive answer from asking guys who work with diffs...my version is I'm running much the same basic mods as you but in a VE R8 which factory is a 3.7 ratio, and with a large cam and an extreme clutch was hard to look cool bunny hopping through carparks and around round-abouts because that's what it wanted to do. I got used to it but I read (lowering the ratio) it can take the edge off the jerkiness of a large cam and give better ecceleration but the trade off was running more revs but the **** fight in most searches seemed to revolve around what you were reving at 100ks, kms per litre, strength of aftermarket gears, whining and 1st gear being useless. I can finally have some input as I got a 4.11 fitted a couple of months ago and I'm loving it. At 100ks I used to sit on 1600rpm now I sit on 1850-1900 which I find sweet f all for the acceleration gained and getting into that rev range that the cam likes faster. The only negative for me so far is that they can't guarantee that it won't make some noise, I was prepared for it but I only get a slight whine when cruising between 80-90k which I don't mind, not sure if it will get worse but only time will tell but so far I'm really happy with the 4.11.

 

[Peterj70]

I've read countless threads about diff ratios to run in VE's and everyone seems to be divided and I couldn't even get a definitive answer from asking guys who work with diffs...my version is I'm running much the same basic mods as you but in a VE R8 which factory is a 3.7 ratio, and with a large cam and an extreme clutch was hard to look cool bunny hopping through carparks and around round-abouts because that's what it wanted to do. I got used to it but I read (lowering the ratio) it can take the edge off the jerkiness of a large cam and give better ecceleration but the trade off was running more revs but the **** fight in most searches seemed to revolve around what you were reving at 100ks, kms per litre, strength of aftermarket gears, whining and 1st gear being useless. I can finally have some input as I got a 4.11 fitted a couple of months ago and I'm loving it. At 100ks I used to sit on 1600rpm now I sit on 1850-1900 which I find sweet f all for the acceleration gained and getting into that rev range that the cam likes faster. The only negative for me so far is that they can't guarantee that it won't make some noise, I was prepared for it but I only get a slight whine when cruising between 80-90k which I don't mind, not sure if it will get worse but only time will tell but so far I'm really happy with the 4.11.

It sounds like what I am looking for, Would like to give it a bit more punch down low.
Did you have to replace the whole diff centre or just gears? was your speedo an issue to adjust to the set up?

 

[ilusiv1]

I took it in to the diff shop, they used my casing and changed the gear set, I haven't had the speedo adjusted yet but im estimating that it's only about 2-3kms out

 

[07GTS]

diff gears won't effect the speedo in the ve's, also what was mentioned by ilusiv1 the bunny hopping is alot to do with the tune for low speed with decent cam, Peterj70 if u want to know the rpm change for any gear/speed just divide that rpm by old diff ratio and then multiply by new ratio and the non hsv m6 have longer main gear ratios so a diff ratio change will liven it up

 

[ilusiv1]

diff gears won't effect the speedo in the ve's, also what was mentioned by ilusiv1 the bunny hopping is alot to do with the tune for low speed with decent cam, Peterj70 if u want to know the rpm change for any gear/speed just divide that rpm by old diff ratio and then multiply by new ratio and the non hsv m6 have longer main gear ratios so a diff ratio change will liven it up

Sweet, I hooked up to my dashcommand app to see if there was a difference in speed read out from the dash speedo but was the same, I was thinking they are obviously getting their readings from the same place.

 

[07GTS]

the speed readout in the obd data will be tru speed and the speedo might read a couple km faster for safety, the reading is from the 4 abs sensors so anything before them wont affect the accuracy only changing the wheel/tyre size will affect it

 

[ilusiv1]

the speed readout in the obd data will be tru speed and the speedo might read a couple km faster for safety, the reading is from the 4 abs sensors so anything before them wont affect the accuracy only changing the wheel/tyre size will affect it

Sweet bruv, thanks for the info.