1UZ manual hilux gear ratio??

[Big_Lux]

Hey,

To the other members who've done a manual 1UZFE swap into their hiluxs, what diff ratio did you guys go for? I've got a 1995 RN105R 4x4 SC utility and I've chosen to go with the R150F gearbox. I'm running 33" tyres and at 100kmph, I'm sitting at 3000RPM..

90% of my driving is on road and the rest is occasional off road. What diff ratio should I change to that will give me better on road economy but not completely wreck off road capabilities?

Any suggestions on sellers of diff gears?

Thanks for any help

 

[4U2QUIK]

http://www.marlincrawler.com/tech/transmission/transmission-gear-ratio-chart

 

[Big_Lux]

Was meant to say diff ratio, not gear ratio.

 

[samsdad]

I'm running the stock diesel Surf 4.3:1 diffs and 5 years on they're fine for both on and off road. That is running 31x10.5x15 tyres so at 110kph the engine in 5th gear is spinning 2700rpm.Don't ask me what she does flat out as firstly that aint quite legal and secondly she runs out of speedo (has the 180k V6 4runner one, yes it is correctly calibrated) With the auto ones that I've built 4.1s seem to be the go and I have built 2 with 3.7 diffs but these were 2001 RZN 4wd luxes.

However if you wish to run say for example 33 inch or larger tyres then this throws a whole new spanner in the works as you need to calculate the rolling radius of your chosen rubber then go thru a whole lot of "X+Y/C=4" to work out the overall gearing. But from a bit of trial and error for others if you want to run 33s then you'd fit 4.56 diff gears to give you the same overall gearing as a stock lux with 4.3 diffs, use 4.3s to acheive 4.1 overall etc

 

[Big_Lux]

I'm running the stock diesel Surf 4.3:1 diffs and 5 years on they're fine for both on and off road. That is running 31x10.5x15 tyres so at 110kph the engine in 5th gear is spinning 2700rpm.Don't ask me what she does flat out as firstly that aint quite legal and secondly she runs out of speedo (has the 180k V6 4runner one, yes it is correctly calibrated) With the auto ones that I've built 4.1s seem to be the go and I have built 2 with 3.7 diffs but these were 2001 RZN 4wd luxes.

However if you wish to run say for example 33 inch or larger tyres then this throws a whole new spanner in the works as you need to calculate the rolling radius of your chosen rubber then go thru a whole lot of "X+Y/C=4" to work out the overall gearing. But from a bit of trial and error for others if you want to run 33s then you'd fit 4.56 diff gears to give you the same overall gearing as a stock lux with 4.3 diffs, use 4.3s to acheive 4.1 overall etc

Mine at 110kph in 5th would sit at around 3300RPM.. Have read through some research that some people have got their trucks to sit at ~2300RPM @ 100kmh on 33s and this hasn't drastically affected their off road capabilities
either.

You wouldn't happen to know what the stock diff ratio a RN105R came out with by anychance? My main goal is to lower the revs when on the highway as that is my main driving area. So if I could find out which diff ratio would allow me to sit on or lower the ~2400-2500, that would be great!

Cheers for the help so far mate

 

[samsdad]

There should be a plate on the firewall which gives the model numbers etc. On that you are looking for the "Trans/Axle code" which on yours may be something like G52 for trans and G*** diff ratio. Now in your case you're probably going to have a diff code like G142 or 145 which is 4.88:1 either 2 pinion LSD for the last digit being 2 or 4 pinion being 5. Given what you've posted about RPM @ 110 I'd hazard a guess that you have 4.8 diffs so ideally you'd want to change to 4.3:1 which are commonly found in the diesel manual LN106 Hilux. Depending on your intended use I'd fit a lokka to the front diff and leave the rear LSD or you could fit either an ARB airlokka to both ends or go Eaton E lokka. I have a Spartan autolokka in the front of the Surf and stock LSD rear and she goes everywhere I want her to go. On road manners are pretty good and fuel economy does depend on the right foot and you resisting the temptation to give some tosser in a wanked up Commonwhore or Fowlcan a bit of what for (trust me that is difficult and I'm 42). Now this also brings into question your choice of gearbox. R series is what you need and diesel manual Surf is where it is going to come from to get the gear levers in the right place. this then opens up another tin of worms in your choice of transfer case. Now the big question to ask is that is your lux solid front axle or IFS as there's a whole lot of other "Hidden traps"

 

[Big_Lux]

There should be a plate on the firewall which gives the model numbers etc. On that you are looking for the "Trans/Axle code" which on yours may be something like G52 for trans and G*** diff ratio. Now in your case you're probably going to have a diff code like G142 or 145 which is 4.88:1 either 2 pinion LSD for the last digit being 2 or 4 pinion being 5. Given what you've posted about RPM @ 110 I'd hazard a guess that you have 4.8 diffs so ideally you'd want to change to 4.3:1 which are commonly found in the diesel manual LN106 Hilux. Depending on your intended use I'd fit a lokka to the front diff and leave the rear LSD or you could fit either an ARB airlokka to both ends or go Eaton E lokka. I have a Spartan autolokka in the front of the Surf and stock LSD rear and she goes everywhere I want her to go. On road manners are pretty good and fuel economy does depend on the right foot and you resisting the temptation to give some tosser in a wanked up Commonwhore or Fowlcan a bit of what for (trust me that is difficult and I'm 42). Now this also brings into question your choice of gearbox. R series is what you need and diesel manual Surf is where it is going to come from to get the gear levers in the right place. this then opens up another tin of worms in your choice of transfer case. Now the big question to ask is that is your lux solid front axle or IFS as there's a whole lot of other "Hidden traps"

Haha yes, tempting to give those wankers a run sometimes. I've already got the R150F gearbox in mine and the hilux is a SFA running 4.88s. So if I get the 4.3s, how much do you reckon I'll be sitting at if I'm doing 100kmh? Transfercase wise, I'm looking for a gear driven one to swap into my R150F

 

[samsdad]

With 31 inch tyres you'll be doing 2600rpm @ 100

 

[Big_Lux]

With 31 inch tyres you'll be doing 2600rpm @ 100

And with 33s? Would it be higher revs or lower?

 

[samsdad]

off the top of my head you'd run about 2500 @ 100 with 33s

 

[Big_Lux]

Cheers mate. Been doing some more research and some people have used the 4.1s Do you think that the 4.1s would be okay for a 5spd 1UZ? I don't want it to be too much of a slug. Was really aiming for better low down torque and low revs at 100kmh

 

[samsdad]

If you're running 33inch tyres you will acheive the same overall gearing with 4.3s as you will with 4.1s and 31 inch tyres. However 4.1s would be the tallest that I'd go on a lux or Surf as any taller than that... Well they tend to turn into a slug

 

[Big_Lux]

No worries. I will try to find both ratios and try them out as I don't have 4wd working yet. Also, the 4.1s are from a 4x2 so will that bolt straight into a 4x4? Thanks for your help mate