VCM 3.7 Diff

[Lumps of cheese]

:rofl:

Some cars will need recalibration while others won't?? What a load of rubbish mate.

The ONLY cars that would NOT need claibrations are cars that get the speedo pulse from the wheel. Last I recall the VE's do not use the signals from the wheels for the speedo.

I've got good news and bad news for you mate.

Bad news; You are so wrong it makes baby jesus cry. Going from a 2.92 final ratio to a 3.45 will result in the speedo being out by about 15kmph at 100kmph.

Good news; if you say your speedo is showing the correct speed, this means that whoever put your diff in recalibrated your speedo already.

ANY change in final drive ratio WILL require speedo re-calibration. Luckily this is a pretty simple process and can be done at Holden for ratio's that are compatible with that model (not sure why but when I tried to get them to reprogram my VX for a 3.73 diff the said they couldn't go it because it didn't come with that model) and any tuner for any ratio you throw in there.

Oh dear, wrong i'm afraid.
Done 2 diff swaps now and the speedo does NOT alter, simple as that.
Unless the calibration fairies did it without my knowledge....not sure now

 

[M500]

I did the 3.7's on my ute and it absolutely torches the tyres! Sure it revs slightly more when cruising at 100 but no real bother. Definately a worthwhile upgrade

 

[Lumps of cheese]

Back to wogboyz original question. Everyone that has upgraded from 3.45 to 3.7 has not regretted it. They may cost a bit but you'll have no trouble selling your 3.45 as a complete set up.

 

[Jarp]

Out of interest the speedo was out by 13% with my diff change. Speed signal in the SIDI is taken from the VSS on the gearbox output shaft and then sent to the ECU and then to the speedo. Fixed thru tune. I've got a bit of a theory that some ECUs may recalibrate themselves based on both wheel and VSS inputs whereas others don't....not sure if the ECU is different in different year models of the VE V8? Either way is tuneable so doesn't matter in the long run.

 

[Jesterarts]

Looks like I was wrong and some VE's get it from the wheels. Maybe it's me that makes baby jesus cry.

So it's looking like depending on the vehicle model the speedo gets it's reading from either the wheels or the box.

And year doesn't seem to play a part. Since we have a 06 calais that is getting it from the wheels and a '10 SV6 getting it from box.

Anyone else shed some further light on this?

Still strikes me as odd that they use 2 methods of working out road speed on the one platform.

 

[WogBoyz]

Thanks for the reply guys, yeah im pretty keen on getting one, wont be for quite a while tho, gotta pay off a few other things first, gm motor sport have a complete 3.7 genuine diff for $1650 so i asked vcm if they would price match it as theres is $1850 and he said yes no worries, id rather buy it through vcm as they look after ya

Also i dont use cruise control anyway so thats good news about the speedo, not a big problem anyway even if it did go out as oztrack can fix it for me

Saving time now! lol

 

[maka5]

Holmart = $1550-

Just trying to save you some $$ lol
:beer chug:

 

[WogBoyz]

Holmart = $1550-

Just trying to save you some $$ lol
:beer chug:

Ohh even better! thanks mate! lol

 

[Gothem92]

Just to add some info. I've got a VZ Sv6 went from the **** 2.9's up to 3.9's my spedo went spasticly out. for example. speedo read 140km's and i was only doing 90... haha. very expensive to get recalibrated at power torque because they dont do much 6's. was 280 for recalibrate.

got told by power torque that with factory 245/45/17's my diff was closer to 4.11's...

and now i sit at 80km's = 2000rpm and 100km's = 2500. in 5th
i've got the A5 gearbox.
1st is about 55km/h
2nd = 90ish
3rd is 125ish?
can't remember 4th.

4th at about 140 was reving at 5000....
and yes i burn a metric ####ton of fuel.
and yes it made a massive difference to acceleration.

 

[WogBoyz]

Just to add some info. I've got a VZ Sv6 went from the **** 2.9's up to 3.9's my spedo went spasticly out. for example. speedo read 140km's and i was only doing 90... haha. very expensive to get recalibrated at power torque because they dont do much 6's. was 280 for recalibrate.

got told by power torque that with factory 245/45/17's my diff was closer to 4.11's...

and now i sit at 80km's = 2000rpm and 100km's = 2500. in 5th
i've got the A5 gearbox.
1st is about 55km/h
2nd = 90ish
3rd is 125ish?
can't remember 4th.

4th at about 140 was reving at 5000....
and yes i burn a metric ####ton of fuel.
and yes it made a massive difference to acceleration.

thanks for that mate, mine wont be as bad as that with 3.7s and the 6 speed manual box