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Diff gears....

calvv8

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Arvo all, Looking seriously at replacing diff gears in my 6 speed V8, Now im thinking 3.7 ratio Thoughts please....


Cheers in Advance
 

SnowDoggyDogg

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See if you can take an E or F series HSV for a spin as they've got 3.7 diff gears in them... should give you the best feel for how short 1st, 2nd, etc is.
 

prenty52

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my 2 cents worth.
Manual maybe...but if you live in a semi rural or rural area (Pakenenham isnt either these days) go the 3.25..far more flexible and driveline friendly.
For a basically stock auto box car they are too low.
I fitted a 3.71 to my 09 VE auto SS ute.(224 rwkw)
Brand new, took it out afer 2000km.
The auto gives no room for the drive line to get over the very low gears, the very high traction and an auto will break the lsd in no time..or rather not break it as sch, it just wont work. Can assure you also that while faster to 120, a 3,25 will work far better and more eficiently across the performance range and will not run out of puff like the 3.71 (in a factory stock SS )
Dont get me wrong, they are great fun and really launch hard around town, but fuel suffers hugely (not that it matters) the drive line is worked so much harder you wont believe it, and you MUST get a Harrop Tru-Trac or similar fitted. the OE lsd just isnt up to the task...that TruTrac adds a whole heap of cost.
Strongly suggest you go 3.25 mate.
 

calvv8

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Thanks Snow, Sounds like a plan, PIR4TE it is an auto, i dont think the Calias V come in a manual but i could be wrong..

And last of all Prenty, Cheers for your thoughts mate,However after increasing the ratio you place LESS pressure on drive train or so i was told by someone in the know, 3.25 is still a big jump from the standard which is 3.08?..Not 100% on that one...

As for the Tru-Track set up i know nothing about them but will do some homework on it...The set up i have now is NOT LSD just standard all over except zorst and tune...If i do the gears say 3.25, will i still need the LSD set up or could i get away with it?...

Also what kinda Coin you looking at for this Tru-Track set up?


Cheers you guys...:beer chug:
 

SnowDoggyDogg

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Your auto is running 2.92 diff gears so it's a big jump to 3.7 for the auto. 3.7 diff gears are in the manual HSV not the autos.
Truetrac should cost about ~$1300ish for the part and maybe half as much again for the labor.
 

ducker85

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3.25 is still a big jump from the standard which is 3.08?..Not 100% on that one...

your car doesn't have 3.08 standard

Calais V's only come in automatics.

the 3.73 ratio is a LLLOOOOOOOOOOOOOOOOOONNNNNGGGGGGGG way away from the 2.92s

its like;
-2.92
-3.08
-3.25
-3.45
-3.73
-3.9
-4.11

Something along those lines which im sure you get.
 

calvv8

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Sweet Mary Mother Of Josef, 2.92! No wonder they take a bit to get going...Cool as bro..I was told even with 3.7s in @100kmph it will sit on around 2100 -2200rpm...

As far as fuel consumption goes well i dont really care but kinda steering towards 3.25 at this stage...My old VN went from 3.08 to 3.9 and i know how much difference that made...it was fun but it was a manual and first second was just insane, i went back to 3.08 so dont want to make the same mistake on this puppy...lol
....
 

ducker85

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I was told even with 3.7s in @100kmph it will sit on around 2100 -2200rpm...


no, no, no, that's still wrong mate.

My VE HSV is stock as a rock LS3, manual, 3.73 and it does about 2,200rpm. Im told HSVs also have a closer ratio gear box so your auto will rev higher. Add 200rpm for ever diff ratio change.

If you have a stock 2.92 now and go 4 steps lower to the 3.73 as you mentioned add 4x200rpm so 800rpm to what you do now at 100km I think you'd be around 2300-2400rpm but im happy to be proved wrong on what your auto V8 does at 100km, I am guessing 1500-1600rpm?
 
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