VCM 3.7 Diff

[WogBoyz]

Hey all

Im thinking about getting the vcm 3.7 complete diff, my ute is manual, im not sure what the standard ss ones are but ill i notice much difference going to 3.7s?

What revs will it sit at doing say 80 and at 100?

Will i need my speedo re calibrated? (ive been told yes and no) and is there anything else i need to update/change or is just a straight diff swap?

Cheers guys

[TinSnips]

SS is 3.45 from factory, so there will be a bit of a difference. Revs should be around 200 RPM higher - speedo will be out slightly, though may still be within the allowed tolerances, so check that out. Not a massive deal for Oztrack to adjust that for you though, I believe.

[WogBoyz]

SS is 3.45 from factory, so there will be a bit of a difference. Revs should be around 200 RPM higher - speedo will be out slightly, though may still be within the allowed tolerances, so check that out. Not a massive deal for Oztrack to adjust that for you though, I believe.

Yeah i just sent steve asking about that, i didnt realise they could ajust the speedo in the tune, by 200rpm isnt too bad, solong as it launches off the line and accerates better then it does (it does it quite well now but want more :P) cus the replacement diff isnt cheap! lol

[StoneX]

SS manual has 3.45, HSV manual has 3.7.

Some cars won't require recalibration, others will. Mine stayed exactly the same changing from 2.92 to 3.45. 100km/h on GPS = 105km/h on speedo before and after change, other people have said theirs needed calibrating. Mine was about 1500RPM at 100km/h before and 1800RPM at 100km/h after, as far as I can remember.

[Jesterarts]

SS manual has 3.45, HSV manual has 3.7.

Some cars won't require recalibration, others will. Mine stayed exactly the same changing from 2.92 to 3.45. 100km/h on GPS = 105km/h on speedo before and after change, other people have said theirs needed calibrating. Mine was about 1500RPM at 100km/h before and 1800RPM at 100km/h after, as far as I can remember.

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.

[WogBoyz]

Oh ok well if oztrack cant but im sure they can, i can just get holden to do it for me, im just tossing up wether its worth the $1800 or so for one, then prob have $150 or so labour too

tough choice indeed lol do you think its worth it?

[Jesterarts]

Mate, from what I understand the SSV ute has a 3.45 standard. Is this correct?

If so, I would suggest you just go the 3.9's if you are willing to take a hit fuel economy wise.

You will notice a difference going from 3.45 to 3.73 but I don't think it will be like a "WOW" look at this thing go difference.

Though I can't comment specifically on a change that size and I have only ever gone from a 3.08 to 3.73 in my VX v6 (Noticed that!) and also comparing a VZ with stock gears to mine with the 4.11's. (Definately noticed that )

I can pretty much guarantee that oztrack would be able to sort of the calibration for you being a tuning shop.

[WogBoyz]

Mate, from what I understand the SSV ute has a 3.45 standard. Is this correct?

If so, I would suggest you just go the 3.9's if you are willing to take a hit fuel economy wise.

You will notice a difference going from 3.45 to 3.73 but I don't think it will be like a "WOW" look at this thing go difference.

Though I can't comment specifically on a change that size and I have only ever gone from a 3.08 to 3.73 in my VX v6 (Noticed that!) and also comparing a VZ with stock gears to mine with the 4.11's. (Definately noticed that )

I can pretty much guarantee that oztrack would be able to sort of the calibration for you being a tuning shop.

lol 4.11s good effort!

Yeah i dont think ill go the 3.9s, from what ive been reading on the ls1 the complete diff change from my one now to the hsv 3.7's ppl have been saying its good noticeable mod best thing they have done ect ect lol and being a full complete diff its just bolt in, so its looking pretty good for 3.7s right now

[Jesterarts]

lol 4.11s good effort!

Yeah i dont think ill go the 3.9s, from what ive been reading on the ls1 the complete diff change from my one now to the hsv 3.7's ppl have been saying its good noticeable mod best thing they have done ect ect lol and being a full complete diff its just bolt in, so its looking pretty good for 3.7s right now

Sweet, if others say the 3.7's give them a grin then go for it.

The best thing about getting higher ratio diffs if you noticed the biggest difference down low at take-off. Which means that you get to enjoy it day to day driving around jsut having that little more surge.

That and I think that most of the LS V8's in Holdens are sluggish at the bottom end and the diff with have a great effect on improving this.

Good luck with it.

[WogBoyz]

Sweet, if others say the 3.7's give them a grin then go for it.

The best thing about getting higher ratio diffs if you noticed the biggest difference down low at take-off. Which means that you get to enjoy it day to day driving around jsut having that little more surge.

That and I think that most of the LS V8's in Holdens are sluggish at the bottom end and the diff with have a great effect on improving this.

Good luck with it.

Yeah its pretty good with take off atm with the new clutch and cam, under about 1300 its not too happy but above that it starts to really get moving so the gears should move it closer to the cams powerband, just gotta save up again now! i swear this is never ending lol


Cheers for the help dude

[StoneX]

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.

You can't argue it with me, I know I'm right as I did the speedo comparison myself. My diff was changed by a local mechanic that has no equipment to recalibrate the speedo

Also, I know 3 mechanics and none of them believed me that the speedo didn't change, including the one who fitted the diff. I couldn't explain why so they just thought I was talking shit...

After some reading to get some proof, it seems some models use the front wheel sensors (yes, it has wheel sensors, they're even in the Pontiac G8 service manuals).
Link
Link
Link

If you still don't believe me, do some research for yourself.

[WogBoyz]

You can't argue it with me, I know I'm right as I did the speedo comparison myself. My diff was changed by a local mechanic that has no equipment to recalibrate the speedo

Also, I know 3 mechanics and none of them believed me that the speedo didn't change, including the one who fitted the diff. I couldn't explain why so they just thought I was talking shit...

After some reading to get some proof, it seems some models use the front wheel sensors (yes, it has wheel sensors, they're even in the Pontiac G8 service manuals).
Link
Link
Link

If you still don't believe me, do some research for yourself.

Hey mate

What year is urs? mine was built mid 08, do you think id have them front wheel sensors?

When i first got the ute, i had 2 speed/wheel sensors or something fail one front one back, set off the abs, trac control ect ect, would that be them u reakon?

[StoneX]

Honestly, I have no idea how your car senses the speed. I assume they all have 4 wheel sensors for the ESP, but I don't know why certain models would use it for speed sensing and others wouldn't. It doesn't make sense but I know mine doesn't use the transmission sensor and other people claim theirs does, so there must be a difference over different models.

I have an 06 Calais.

[WogBoyz]

Honestly, I have no idea how your car senses the speed. I assume they all have 4 wheel sensors for the ESP, but I don't know why certain models would use it for speed sensing and others wouldn't. It doesn't make sense but I know mine doesn't use the transmission sensor and other people claim theirs does, so there must be a difference over different models.

I have an 06 Calais.

Ohh ok, its not a big deal as mines remote tuned oztrack can just send me a update and ill flash it on all under 5mins lol, will be intersting to see if mine goes out or not

[tomholzy]

3.7s go way harder than the standard 3.45, feel so much better!
when I got mine done I was told the speedo reads from the wheels so it will be fine, but the cruise control will be off, so either way you should probably get it done, although I know someone who installed one themselves and didnt touch the tune and there was no problems

[loku16]

oooohhh.. closely watching this thread! I'm looking to get the same with m 30K service Let me know what price you end up getting quoted for full install.

[azzss]

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.

Guess what mate, your wrong and stonex is right. Done this myself on my wagon (09 model manual) went from 3.45 to 3.7 did complete swap out of diff did work myself and speedo still 2km/h fast as it was with old diff ve's have wheel sensors i'm told

[EnFoRcEr_001]

Guess what mate, your wrong and stonex is right. Done this myself on my wagon (09 model manual) went from 3.45 to 3.7 did complete swap out of diff did work myself and speedo still 2km/h fast as it was with old diff ve's have wheel sensors i'm told

Correct, replacing diff in the ve's doesnt change the speedo, I have done the upgrade in my sv6 from 2.9s to 3.45 myself (no calibration) and the speedo didnt even change. So they definately take the speed from the wheels.

[maka5]

VE V8 3.70 LSD COMPLETE DIFF ASSEMBLY (Shot Peened Gearset)

Try this .. bit better then $1800

[azzss]

VE V8 3.70 LSD COMPLETE DIFF ASSEMBLY (Shot Peened Gearset)

Try this .. bit better then $1800

Thats what i did, bought new diff from holmart, did the changeover myself (not too bad a job) and sold off orignal diff to a auto owner (stonex!) just saves having to muck around with crown wheel and pinion's and getting them setup/fitted plus you'll have a complete 3.45 LSD to sell. RPM is 1700 @102km/h (100km/h gps) with 3.7's in 6th gear standard SSV wheels and tyre size (19's). VE's are fitted with m12 gearbox standard as fitted to vz monaro and hsv's so they have shorter gear ratio to a vz ss. I read somewere that fitting 3.7's to a ve manual was around the same as 3.9-4.11's in a vz.
Cheers.

[Lumps of cheese]

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.