Offroad-Express

Just finishing off my conversion Holden ecotec motor into my Hilux and I've got it running mint. However the gearing isn't correct for the motor it currently has a G52 gearbox and 4.88 diff (I think), and im running 31's looking to go to 33's bit its revving to high at 100km/h sucking threw the gas so wondering what my options are on different diff heads what can I use? to bring revs down to increase economy revs at 100km/h currently 2700 rpm looking to go around the 2000rpm range as that's what this motor should be curzing at 100km/h (used to own a VT wagon).

Cheers Ash

What rpms is it running at 100k's now?

Use one of the online calculators to compare your current setup to what you want inc tyre size...
Going to 33's will drop the rpms v's speed.

Here is one for you to try...
http://www.marlincrawler.com/java/getspd_calc.html

current rpm is 2700ish at 100 want something like 2200 which from calculator is 4.1 diffs or lower depends what I can get to fit and cost. can I get heads to fit? I think I remember reading somewhere that the 4.88 diffs are of a different size and not interchangeable or something along those lines.

cheers

Yes, you can NOT fit aftermarlet R and P in to an original 4.88 as the orig 4.88 ring gear is thinner.
you would be better to sell yours complete and then buy some higher ration diffs.
Not sure if 8" diffs came standard with 4.1, certainly did 4.3's.

Cheers
Tim

yep they do and you can get them in 2 spider,4 spider and slippery

suzolla wrote:Yes, you can NOT fit aftermarlet R and P in to an original 4.88 as the orig 4.88 ring gear is thinner.
you would be better to sell yours complete and then buy some higher ration diffs.
Not sure if 8" diffs came standard with 4.1, certainly did 4.3's.

Cheers
Tim

so are we talking about the entire diff or just the heads? so sounds like I need to save some dollars and get myself some air lockers so I can install at the same time as I do diffs.

Just heads... the diff housings are practically the same..

kbushnz wrote:Just heads... the diff housings are practically the same..

Sweet thanks bro. any places I should look for some heads? or is Trademe going to be my best bet?

Toyota 8"diff heads are common as, they used them in most large RWD sedans, hiluxs 2 and 4wd, hiaces liteaces etc etc. There are about 11 ratios from 3.2ish to 5.1 factory and 5.29 aftermarket.

Upshot is when looking, think Toyota not just hilux.

5.29 was also factory (early 70's hiace van) not many left now though.
I would be getting tyres sorted first if I was in your shoes, then you know exactly what you are playing with in real world situations Ie high and low range.

what model Toyotas had 3.9 diffs or 4.1?

KZN130 Surf autos have 4.1.

super custom hiaces .

pm'd you an offer

1st gear in hiluxs are quite tall and and I would be more worried about burning the clutch out if you were to change diff ratios.
Just get bigger tyres, just my 10 cents
mine has 4.8s aswell and cruise's at 80k at 3000rpm on 31s (4speed) but I can live with that

tintin wrote:1st gear in hiluxs are quite tall and and I would be more worried about burning the clutch out if you were to change diff ratios.
Just get bigger tyres, just my 10 cents
mine has 4.8s aswell and cruise's at 80k at 3000rpm on 31s (4speed) but I can live with that

Nah I've got a V8 clutch system no issues there also I'm planning on interchanging for my tyres so normally running 31's and then going to 33 as my off roading. I couldn't live with 3000rpm your got a 3rz which I would imagine wouldn't be that bad on the gas at 3000rpm's where as I've got a torque monster v6 which at 3000 revs is sucking so much fuel I can literally see the fuel gauge needle moving towards "E" ha-ha I'm trying to improve my fuel economy. plenty of grunt to turn the wheels in 1st even with different diff ratios. Heck with the clutch I can move off in 3rd no problem. Its like moving off in 1st with the old motor.

also I don't want to cruise at 80k id much prefer to sit on 100 where applicable.

I put the original 2lt petrol back in just to get going, we are moving at the end of the month and didn't want to move a big pile of parts again

tintin wrote:I put the original 2lt petrol back in just to get going, we are moving at the end of the month and didn't want to move a big pile of parts again

Ah I see, well you'll have to move and then rip that puppy out for the 3rz. nothing like a new motor in an old rig!