GQ TD42 diff gear questions

[rumpig89]

gday ive been looking through the search but havent had any luck on some diff ratio questions ive got.

I currently have GQ TD42 with aftermarket turbo and 4.1 gears, 35" tyres.

I am looking into fitting 4.3 or 4.6 gears. The wagon performs well off road but it would be nice to be able to crawl a little more sometimes and on the highway it is hardly revving at 100kph, but i do notice if im working it hard through hills at 100 or towing the temp does creep up and the engine sounds like it is working really hard and pulling full boost (9 pound intercooled).

I understand that 4.6 gears take it back to nearly standard stock ratio with 31" tyres. but:

IF i put 4.6's in will i find them too slow for everyday around town/highway driving?

As the engine will rev slightly higher at 100kph will i be chewing through more fuel or will i prob save fuel because of the reduced load on the engine?

Is this likely to cause the engine to operate a little cooler?

Not interested in putting transfer gears etc in yet.

any info is appreciated
cheers

[nastytroll]

31" and 4.11 is a similar ratio to 35" and 4.625. I like running 35" and 4.11 as an everyday ratio on a td42 turbo. I didn't find anything wrong with it.

You could put 31" back on and go for a drive and make up you own mind.

If you find 5th gear too high the use 4th. Roughly there is a 600rpm difference between 4th and 5th at 100km/h, there is roughly 375rpm difference between 4.11 and 4.625 in 5th at 100km/h.

I could be wrong but the added engine load will give better performance from the turbo.

My ute with 37" mtr and 4.11 was getting better economy then the girls wagon running 33" maxxis 751 and 4.11 on a run from bris south through summerset to cruiser park. That route covers town, hiway and mountain range. There was only about 150 kg empty weight difference and I had my ute loaded fully for the trip. Ute was running 7+2 and wagon 4+2 lifts.

I will be running 4.11 and 85% trans gears in the girls car, and 4.11 and 43% gears in my ute.

If your going to spend the money get the 4.625 gears, but for similar outlay I would do trans gears.

If only running 35" tyres 43% gears are more then low enough.

[rumpig89]

thanks mate. yeh i have been waiting for the rain to stop so giv it a run with 31's.

My ute with 37" mtr and 4.11 was getting better economy then the girls wagon running 33" maxxis 751 and 4.11 on a run from bris south through summerset to cruiser park. That route covers town, hiway and mountain range. There was only about 150 kg empty weight difference and I had my ute loaded fully for the trip. Ute was running 7+2 and wagon 4+2 lifts.

are both these cars turbo TD42's? cause thats impressive

[nastytroll]

Yeah both td42, wagon has stock gu kit with 3" dump and exhaust, ute with safari intercooled kit and 3"exhaust no mufflers.

Both running fueled up 10mm pumps.

I'm supprised no other comments yet.

[anthonygq]

in my old gq ute with td42 n/a with 35 put 4.3 diff gears in it drives a shit load better on and off road

[nastytroll]

in my old gq ute with td42 n/a with 35 put 4.3 diff gears in it drives a shit load better on and off road

Yes N/A is a little different to turbo, have a look at dyno sheets for torque curves on n/a to turbo. Any of the aftermarket turbo kit companies will have a comparisson sheet available.