How to modify V8 GXL Wagon overdrive

[ngt206]

Don't get me wrong, I'm ok with my Landcruiser, but the V8 just doesn't need to be revving at 2500 at 100 kph!!

Is there an economical way of getting more out of the factory manual gear system?

I've heard of a modified differential out there, but have no solid leads

And at 23,000+/- the automatic conversion option is not a cost effective alternative, plus I want to stick with manual.

[rellim60]

I have the same question for a 2013 gxl 4500 single cab....

[kenuppa]

I phoned Difflap in September 2011, left an inquiry re changing diff ratios.

I then emailed them in October 2011.

I recieved a reply stating that someone would contact me to discuss options.

Still waiting....................

http://www.difflap.com.au/

It must be possible to change the crown wheels and drive gears in the diffs. People who race cars like Holen Torana and Commodore change diffs for each track they race at.

Rgds,

Ken

[Hiro]

Any change to diff ratios will affect EVERY gear, not just overdrive - say you want to get top gear down to 2000rpm for 100kph, that's a 20% change which means every gear will be 20% taller.

And anyone who is racing and changing diff ratios depending on the track would be running complete aftermarket diffs anyway (and most people aren't that serious), not modifying stock diffs

[kenuppa]

That is the idea, change the diff ratio.

How could you possibly change just one gear?

The V8 Diesel has so much power and torque, a 20% increase in ratio could be done.

Max torque is from 1200 rpm. You can change up and pull away at 1500 rpm.

When I take off in the morning, I am in 4th gear by 50kph. If I use 5th in 60k and 80k zones, what do I use when I get onto the freeway?

Rgds,

Ken

[Hiro]

That is the idea, change the diff ratio.

How could you possibly change just one gear?

The original post was about changing the overdrive - I was simply pointing out that changing the diff ratios would change all gears, not just overdrive. Although depending on what gearbox the L/C uses these days, there might be a different ratio box in another model that has a taller top gear

The V8 Diesel has so much power and torque, a 20% increase in ratio could be done.

Max torque is from 1200 rpm. You can change up and pull away at 1500 rpm.

When I take off in the morning, I am in 4th gear by 50kph. If I use 5th in 60k and 80k zones, what do I use when I get onto the freeway?

You just answered your own question - nothing wrong with staying in 5th all the way from 60 to 110. Hell, I can potter around town in my Corolla in 5th @ 60kph, the same gear I use at 110kph on the freeway (granted it is doing 3200rpm on the freeway, but it's a 4-cylinder city car, not a cruiser). Not every car (especially not 5-speeds) need moon-shot gearing like a 6-speed SS Commodore. Remember that L/Cs are designed to be loaded up - an extra two tonnes0 of cargo and/or trailer means you want to have slightly shorter ratios so you're not constantly changing down a gear at the slightest incline

[Hiro]

Quick look at the specs, since a "V8" Landcruiser could mean several things:

1VDFTV turbo diesel V8

Max torque: 430Nm @ 1200-3200 rpm (single, Troopy), 650Nm @ 1600-2600 rpm(twin, 200-series)

1URFE

Max torque: 439Nm @ 3400rpm

2UZFE

Max torque: 410Nm @ 3400rpm

If cruising rpm is the same amongst all models (and I wouldn't be surprised if the diesels are taller due to the lower red-line), 2500rpm @ 100kph, then both petrol engines below max torque (which means a kickdown for overtaking), and both diesels are bang in the meat of their torque "plateau".

[Scooter80]

Hi guys,

A late reply I know, but I have done some research for myself and a manual lock up torque converter is the go. I am considering one at the moment and the only consideration is a bigger transmission cooler as the transmission will be working harder not the donk (hence the transmission wants to stay in 5th not 6th as the box is working harder and heating up more). I'll post here again once I get the mod done.

[trentmeyer23]

Hi guys,

A late reply I know, but I have done some research for myself and a manual lock up torque converter is the go. I am considering one at the moment and the only consideration is a bigger transmission cooler as the transmission will be working harder not the donk (hence the transmission wants to stay in 5th not 6th as the box is working harder and heating up more). I'll post here again once I get the mod done.

You are referring to an automatic transmission, this topic is based on a manual transmission.

For the manual transmission there are aftermarket overdrive assemblies available for certain vehicles.

[Scooter80]

Ah yep! Thanks for that!

[ngt206]

Gidday all, and thanks for the comments/ideas coming through. It's been interesting reading

Looking back (crikey, it's almost a year since the post went up) I guess I should have titled the thread "How to modify the gear ratio on a V8 Landcruiser"

Since posting I've done a few mods, most notable swapping out for a 3" exhaust, which I believe has improved the bottom end torque dramatically.

You had me going there for a moment Scooter, but I guess you're referring to the auto transmission right??

In a perfect world, I reckon a 6 speed gearbox would be the go, although I'm interested in your feedback Trentmeyer with regards the aftermarket overdrive you mention, and how practical and workable that is as an effective modification for my vehicle.

Are you able to be more specific on this forum as regards a manufacturer, or are you bound by secrecy?

Many thanks for any help

[trentmeyer23]

trentmeyer23 with regards the aftermarket overdrive you mention, and how practical and workable that is as an effective modification for my vehicle.

Are you able to be more specific on this forum as regards a manufacturer, or are you bound by secrecy?

Many thanks for any help

"Bound by secrecy?" Nope.

I believe Gear Master used to make them for the Australian market, but I am not sure if they still exist. I know that Gear Vendors in the US make assemblies, but I am not sure whether they would make anything for our market. They would be a few places to start looking. You will need a shortened driveshaft if you were to take that option.

[ngt206]

Thanks for your help Trent. Looks like Snake Racing (supplier for GearMaster) only have the after market reduction gear, but will send them the question.

And we'll see what Gear Vendors come back with. Looks like they only deal with Yank Tanks, but you never know...

[trentmeyer23]

It's a very specific/niche market, so I would expect not a lot of support out there.