[jimny_timmy]

macguyverjimny wrote:

Im having trouble to source a auto vvt,

So i am investigating if i cant buy the different parts from suzuki and perhaps change my vvt transfer to an auto one.
After some research on parts catalogues, it seems that there are only about two or three parts that would needs replacing, namely a chain an input gear and output gear, so in othe words the chain and both sprocket gears , but i am first investigating,

So thank you guys, if anyone have experience on an auto vvt and know if its planatary gears for lowrange or helical please let me know

Thanx for an awesome thread Shep, alot of good info here,

http://bit.ly/1fbjHJN

Hit these guys up... They'll have one.

I paid about $395+ postage.

[pete_79]

Sounds like this is a pretty common upgrade these days with good results for those on bigger rubber.
I know all the guys running 30s are happy with this set up, but would be interested to hear if anyone is running smaller tyres with these gears and what the highway revs are like.

[Jezza86]

it would be doing over 4200rpm with 235/75 15s for sure

[JayKay]

Jezza86 wrote:

it would be doing over 4200rpm with 235/75 15s for sure

mine was doing close to that on the highway with 30's

[jdk81]

From my gear calcultator
Figures used, in case they are incorrect

m13a vvt manual
5th gear 1:1
diff gear 4.3:1
vvt auto transfer 1.32:1

With a true 235/75R15 (28.8") for diameter it will be 4102rpm at 100 km/h
Based on true diameters
28" tyre = 4234 rpm
29" tyre = 4088 rpm
30" tyre = 3951 rpm
31" tyre = 3824 rpm

NOTE: True diameters can be pretty far out form the manufacturers designations and manufacturers claims.

[pete_79]

^^^ Excellent, thanks mate.

[austuff]

With Deestone 235/75R15 muddies and quite a bit of extra weight like bullbar, sliders, bash plates, tools, tirfor and myself I'm sitting on a tad over 4100 rpm at 100 KPH. Speedo could still be a little out though wouldn't be much judging by the other traffic.

[Jezza86]

shep and i on 30's both got the same result, 4150rpm @ 100kph gps. dont see how a 235/75 r15 can be turning slower being smaller diameter. his is new and mine is 2010

[jdk81]

Unless the gear ratio, diff ratio or vvt auto xfer case ratios are wrong (which was why I showed which numbers I used).
We need to consider the errors involved which can be significant when trying to be exact with the numbers.

For example
Speedo reading error... the difference between 100km/h and 103/km/h on a 30" tyre is 119 rpm ( a couple of km/h is hard to accurately spot on a needle)

Tacho errors - they are not really accurate, let alone the eye seeing them for a precise figure (unless you are using an IR laser tacho etc).

and as I mentioned before...
True tyre sizes!
These are not consistent, different sizes, different manufacturers etc means these results will never correlate exactly to others.

There are tolerances in the speedo calibration and manufacturers ensure the speedos generally over-read the true speed by up to 10%. i.e showing 100 km/h on the speedo, when the camry driver is doing 90km/h and driving those with GPS crazy.
Changing brands of tyres which are the same size can affect the speedo, just like air pressure etc by the ADR forcing manufacturers to ensure the speedo over reads (and the operator is responsible for ensuring the speedo is ADR compliant) removes all wriggle room for people to challenge speeding fines.

Simply for these purposes an approximation is good enough, as the only exact known is the gear ratios.
Don't get too lost in the exactness

[Jezza86]

in short we need 1 car, a gps speedo, a Bluetooth rpm reader to accurately read the rpm to as many decimals as we can, and a shitload of tyres and rims at multiple pressures, brands, and sizes and tread paterns.

anyone board?

[zukenutter]

Jezza86 wrote:

shep and i on 30's both got the same result, 4150rpm @ 100kph gps. dont see how a 235/75 r15 can be turning slower being smaller diameter. his is new and mine is 2010

GPS speed?

[shep]

My speedo is 101-102 for a GPS 100kph

[JayKay]

shep wrote:

My speedo is 101-102 for a GPS 100kph

wow really, mine was 100 GPS for 109/110 Speedo

[jimny_timmy]

Mines near bang on 100 for 100. Maybe a smidge toward 101 on the speedo

[jimny_timmy]

And at 4150

[zukenutter]

JayKay wrote:

shep wrote:

My speedo is 101-102 for a GPS 100kph

wow really, mine was 100 GPS for 109/110 Speedo

100 GPS for 108 Speedo for me

[shep]

JayKay wrote:

shep wrote:

My speedo is 101-102 for a GPS 100kph

wow really, mine was 100 GPS for 109/110 Speedo

zukenutter wrote:

JayKay wrote:

shep wrote:

My speedo is 101-102 for a GPS 100kph

wow really, mine was 100 GPS for 109/110 Speedo

100 GPS for 108 Speedo for me

Do you have late model jimnys with a auto transfer for gearing reduction?

[JayKay]

I have a 2008 Model Manual VVT NS Have/had a Auto Transfer of the same year.

[Jezza86]

now this is interesting. 2010 jimny, 2010 vvtauto tcase, 100@100gps +/- 1kph.

i want to find a set of 235's that are the same height (diameter) as a bfgKM2 muddy. in my mind a 28" tyre should never be 30", but if there out ther id like to know. should providebetter fuel economy and give the height at the diffs i want. other option is those trailer tyres shep has, 700something... but they also didnt look very sticky

[shep]

The size is 750r15. I don't thing a radial tyre in that size is available

[zukenutter]

shep wrote:

Do you have late model jimnys with a auto transfer for gearing reduction?

Me?
No, but what difference would it make? Speed is read from rear output of the transfer, so as long as we have the same diff ratios and both have 30s the reading should be the same.

[shep]

It isn't the same, that's my point. My speedo under read by about 15% with stock gearing and 30" tyres but now it is pretty much spot on.

[jimny_timmy]

Yeah there's something with the readings... Mine was out by 6% with my trial jimny gears but the odometer was out 11%. Now being spot on, the odometer is still out 3%. The only way I can see this happening would be there being two sensors right? I can't say I've seen any others???

[JayKay]

Where with my 08 Jim and 30's with the stock case i'm about dead on 100@100

[zukenutter]

So digital speedos are a bit all over the shop. Maybe facelift Jimny has some difference with the speedo.

[zukenutter]

There was a difference in the way my two Jimny speedos have worked. Different models.

[pete_79]

Cheers guys.
I was more interested in the RPM at highway speeds in manuals with auto transfers running tyres under 30 inch.
I'm thinking about gearing, but not looking to go massive tyres. Will most likely go with something like Mr Nutter, but not for a while longer it think. All the good camping spots are at least 2-3hrs of highway driving and I couldn't do 4200+ rpm for that long...

As for speedos, they are most def all over the place, mine at stock was 5k's out to the gps, running 215s it's spot on...

[shep]

I recently did a 9000km trip and cruised between 4500-5000rpm and the car loved it.

[Jezza86]

holey shit, that's through testing

[shep]

Jezza86 wrote:

holey shit, that's through testing

Was towing my camper as well. Cruised at 110-120kph.