overdrive 5th gear

[poindexter]

Hi all,
Has anyone fitted the overdrive 5th gear to their ZD30?
My coil cab (CRD) has the standard tires (265) and would like to know if gearing the ZD30 for 2000rpm @ 100kph is feasible. Currently it is geared to do 2500ish @ 100kph according to the GPS.
I do plan to do the usual mods to the engine to fatten up the torque.
My rationale is for touring and aiming to keep fuel consumption down.
I'm aware that there are 3 ratios available, just wondering if its worth it.

cheers

Ralph

[mudski]

Hi all,
Has anyone fitted the overdrive 5th gear to their ZD30?
My coil cab (CRD) has the standard tires (265) and would like to know if gearing the ZD30 for 2000rpm @ 100kph is feasible. Currently it is geared to do 2500ish @ 100kph according to the GPS.
I do plan to do the usual mods to the engine to fatten up the torque.
My rationale is for touring and aiming to keep fuel consumption down.
I'm aware that there are 3 ratios available, just wondering if its worth it.

cheers

Ralph

There is? Where? I would be keen as I have a box here I want to build soon. But it depends on if you tow too. If you do would keep it the way it is.

Come to think of it. Its a big job to remove the gearbox and strip it down and change the ratio. Would be easier to change the ratios in the diffs I reckon.

[poindexter]

Hi Mudski,
Marks Adaptors have the 5th gears, and, according to them, no need to pull gearbox, just drop the transfer case.

[Drew]

Hi Mudski,
Marks Adaptors have the 5th gears, and, according to them, no need to pull gearbox, just drop the transfer case.

Any chance of a link ? Thanks

[fxst78]

Running at 2000rpm at 100kph will be stressing your motor a lot IMHO, and you may find you actually use more fuel. High rpm does not equate to high fuel use in a diesel. Higher rpm with low EGT versus lower rpm with high EGT, the low rpm is actually burning more fuel and placing more stress on your motor (very simplistic explanation).

[emm]

Running at 2000rpm at 100kph will be stressing your motor a lot IMHO, and you may find you actually use more fuel. High rpm does not equate to high fuel use in a diesel. Higher rpm with low EGT versus lower rpm with high EGT, the low rpm is actually burning more fuel and placing more stress on your motor (very simplistic explanation).

What's an EGT? Sorry got no idea... our patrol is an automatic.

Sent from my GT-I9305 using Tapatalk 2

[megatexture]

What's an EGT? Sorry got no idea... our patrol is an automatic.

Sent from my GT-I9305 using Tapatalk 2

Exhaust gas temperature

There is? Where? I would be keen as I have a box here I want to build soon. But it depends on if you tow too. If you do would keep it the way it is.

Come to think of it. Its a big job to remove the gearbox and strip it down and change the ratio. Would be easier to change the ratios in the diffs I reckon.

I'd love to do my diff ratios to drive 33s like standard but its a bit to much $ for my shallow pockets lol

[mudski]

What's an EGT? Sorry got no idea... our patrol is an automatic.

Sent from my GT-I9305 using Tapatalk 2

Oh! So there is a mod for auto's to add another gear your saying? I have manual sorry im out of ideas.

[Drew]

IMO the egt is more important than saving a few litres of fuel. When they go up you have two options, take the foot off the go juice or drop a gear (higher revs). It's important to remember that in certain circumstances the second option isn't enough so you should take take your foot off the accelerator a little to get the temps down.

There was a great post somewhere that describes how a diesel is different from petrol. The one thing that I think I got right was when you dump more fuel into a diesel it burns hotter (to produce the torque they do), not paying attention can kill your engine.

I get 100kph at around 2250 rpm so I guess that's the difference between chassis.

I'm assuming you're not towing ?

Like it was said before dropping rpm for same speed doesn't always equal better fuel economy (I'm using a scangauge).

[threedogs]

I think you're going the wrong way by dropping revs at hwy speeds, totally agree with fxst78.
You might be better off changing diff ratios to suit the larger tyres we run,
Doing it the other way your peak power will be at 130kph, impractable IMO
I think those reduced 5th gears are better suited to Duramax or 6.5td conversions.
maybe even LS1, Going to be peed off if you fit them and not all cracked up as could be.
Leave the ZD30 alone its fine as it is, no big power machine, As I always say its only 3ltrs
and highly tuned as is, best spend some money on keeping it efficient.
Its never going to win any best motor awards, just NADS it and leave it, gearbox and auto included
unless you want reduction gears