Reduction Gears

[Winnie]

Thanks Daz, yeah it's a 5 speed. I turn the gas off and the A/C on, which makes a small difference, but not enough. I'll look into it when I get home from work. So changing the ratio will only affect 4wd ? Not 2wd ? Would it tow better as well ?

Diff ratios will affect 2wd as well Kat. It will make towing better for sure.

[Maxhead]

Crap, I hate it when not every one agrees.... I run 33's. Dont plan on changing that any time soon...

Yezah, but Dazz is a bozo and has no idea about stuff...LOL just kidding BTW!
IMO, I wouldn't ferk with diffs with 33's and just whack reduction gears in. Patrols suck with low gear compared to Toyoys

[Winnie]

The diff ratios are only going to change your low range by bugger all though, reduction gears are the answer if you are worried about your car running down Hills. I would love to have the 43% reduction =)

[MudRunnerTD]

I appreciate what Kris is saying for sure. Remember he drives a CRD3.0. The TD42T is a different animal though. if you have the 3.9s then they are looow. this is what i have and great for the flat hwy but in the igh country i tend to go to low range and use 4th and 5th allot rather than struggle in hi 3rd dropping back to hi2nd all the time. sluggish. running 35s is worse and with the trailer on drop another gear.

The diff ratios will make the car Tow with pleasure too. Should not bog down as much, will take off easier and pull up hill better with a load on.

[Ben-e-boy]

Diff ratio change wont even come close to a transfer case gearset.

A cruiser has a factory ratio of approx 2.8:1 a patrol has 2.02:1. A cruiser low range is so much better than a patrolSo if you installed 43%ers it would take your low range to (if my maths is right) 2.88:1. My 85%ers take my low range to 3.74:1

85% is for crawling they dont go fast but will tractor along all day

Example.
I have 35 inch tyres, 4.11:1 diff gears, a first gear ratio of 4.556:1 and transfer case gear ratio of 3.74:1

At 800 rpm I have a crawl ratio of 70.03:1. In the ute as it stands

With stock transfer gears and the same everything else I gave a crawl ratio of 37.82.1

With 43% gears my crawl ratio is 53.93:1

Compare that to a diff ratio change.. (dont forget these figures are based on my ute)

If I left the stock transfer gears in and changed the diff to 4.3. I have a crawl ratio of 39.57:1

As above but with 4.6:1 diff gears I have a crawl ratio of 42.33:1


As you can see the transfer case gears make a much bigger difference than just diff gears for low range

Most of this little climb is done at idle, with 85% gears......no speed just tractor

[Maxhead]

Yes, I should have considered the motors but I thought the running gear ratios were the same...oops Hmmm

[macca]

Swapping 3.9's for 4.3's is a change of about 10%. Not enough for off road engine braking that you are after. The diff change comes into its own on road with bigger tyres or towing as mentioned. Running 33" tyres is borderline for a ratio change, be good with 4.1 diffs possibly. But reduction gears offer more for the money spent. This is my experience and thoughts, made the decision to do the gears for the same reasons you are looking into this. Good luck.

[MudRunnerTD]

I was not suggesting Diff gears would be comparable to transfer gears by any means though Bene. As per your maths there is a massive difference.

So the big question is How Much reduction does Kat really need. That's the point I am making I suppose. Winnie stated he can go down Billy goats with hardly any braking. The odd tap and that's enough, low first holds well. I bet he has 4.1 diff gears and it gets the job done.

If Kat has 3.9s and is chasing her brakes down the same hill then she may really only need a sublte change to achieve her aim. Going to 4.3s will give her what she is chasing. No it still won't be as low as the 60 but should crawl pretty well down Billy Goats. The bonus would be the extra torque in hi range for when towing.

If you can pick up a pair of 4.3s for $600 or so and Steve throws them in for the win I think your next trip up and down Billy Goats would be very different.

[MudRunnerTD]

Yes, I should have considered the motors but I thought the running gear ratios were the same...oops Hmmm

Yours would be the 4.3s that I'd be recommending.

[Winnie]

Well Kat, it's settled. Swap out your diff ratios and get a set of reduction gears, win win =)

I've got no idea what diff ratios I have? Stock 93 TD42 manual gears whatever they are