[cyprus73]

Hi all.

I just got it back My Suzuki Sierra 88 WT back from the tuner, it is running a 1.6 with 32/36 weber, extractors and 29" tires, 3.7 diff ratios.
Was sitting on 100km/h at 4000RPM. With the tire change i know the speed would be out and that would be about 110km
Thing the RPM's are high and was looking at what I can do the fit it without going back to the 26"
Thks
Chris

[bumstein]

What size tyres are you running?

If your lookin at dropping the revs you need to increase tyre size, not decrease it. Are you running reduction gears in your transfer?

[jdk81]

Tried 5th gear?

[MrRocky]

Nothing wrong with 4000rpm at 110
In fact id say its spot on

[Reubs]

Stock Coil Sierras run 4000RPM at 110hm/h. Perfect.

[shep]

My jimny does 4150@100kph and I am about to set off on its third half lap of oz.

[cyprus73]

Hi all.
29" tires. Don't believe it has gear ruduction
In the transfer. That was 5 th gear lol

[alien]

My WT sierra with 31's and 5.14 tcase gears with 1.6efi turns about 3100rpm at 90km/hr in 5th.

I do know that at 5200rpm i'm doing 141km/hr (GPS confirmed rather than speedo).

It's been ages since i sat on 110 so i'm unsure what my RPM would be there, but maybe the above will help.

Maybe you've got the switched NT tcase which is giving you some more reduction?

[jdk81]

Provided it is 4000 rpm or so at 100 km/h by gps and you are in 5th with 29" tyres.
Perhaps it has 5.12 diff gears, or possibly (less likely) a combination of xfer and vitara/gv diff gears.

[tanshi]

yeah as i told you on facebook those revs arent right for the gearing you think you have.

so you are either going faster than you think or some where your gearing is different.

a 1 litre transfer case and doing 115 kmh would come close to what your seeing rev wise

[MrRocky]

Yeah u gotta use gps to check speed
Mines nearly 15 km out at 110

[Gwagensteve]

Yep, gearing is not standard.

[Gwagensteve]

It gearing was standard revs would be 3265

[cyprus73]

Hi All.

Appreciated your feed back. I can confirm that the diff ratio is 3.7 as I changed them recently
as the original ones had shit themselves.

The transfer case is another thing. Not sure what previous own did there.
Ill gps the speed and get back to you all.

Thks.

[alien]

Just stick 31's on it and call it good =) lol

[Gwagensteve]

you have a 1.0 transfer or 4.1 transfer gears. If you're reported speed and revs are accurate.

[alien]

Low range RPM and speed figures would identify if it's got 4.1 tcase gears or not.

[Gwagensteve]

Hmm, in front of my gearing calculator.

You were seeing 4000rpm at an indicated 100km/h on the speedo, yes? (not actual road speed measured with a GPS?)

That means tyre size and diff gears aren't relevant. The only thing that changes the ratio of speedo reading to engine revs are transfer gears.

With my calculator, it looks like you have 6.5:1 transfer gears in the car. I get 4070rpm@100km/h shown on the speedo with 6.5:1 transfer gears in the car.

With your tyres in the mix (assuming they are actually 29") revs at an actual 100km/h will be 3645rpm which is pretty much spot on.

you can check this easily. Put the car in 4L. Leave the front hubs unlocked. Jack one rear wheel off the ground (assuming you don't have an auto locker or spool). chock the other wheels.

Turn the front or rear driveshaft 1 turn. The input shaft from the gearbox to the transfer should turn 6.5 times.

These calculations are only valid if you're talking about speedo reading and not speed via GPS. If it's actual road speed you have even more gearing reduction so the diffs couldn't be 3.7.

[cyprus73]

Hi.

These were speedo reading of 100km tacho around 4000rpm and tires are 255/70/15 which
makes them about 29.1"

I guess its a bonus that it has gear reduction. Wasn't told it had them when i purchased the car about 6 months
ago.

Appreciate all you info, especially you Steve you've been a great help.

Chris.

[MrRocky]

Get a gps on that bad boy your speedo at 100 is in reality prob closer to 110/115

[vet 180]

cyprus73 wrote:

Hi.

These were speedo reading of 100km tacho around 4000rpm and tires are 255/70/15 which
makes them about 29.1"

I guess its a bonus that it has gear reduction. Wasn't told it had them when i purchased the car about 6 months
ago.

Appreciate all you info, especially you Steve you've been a great help.

Chris.

Throw on a set of 31's and call it a day