Advice on engine gearbox upgrade for a 16"

[syncropaddy]

If you are set on changing the diff, I would go for the 5.43 but dont forget you have to change the front one as well. With standard gears and 205/80/16 tyres at 3350 rpm you will be cruising at 110 km/h or there abouts.

[bigblue16]

If you are set on changing the diff, I would go for the 5.43 but dont forget you have to change the front one as well. With standard gears and 205/80/16 tyres at 3350 rpm you will be cruising at 110 km/h or there abouts.

Hello again,

Thanks for the figures. I would like to know what program you are using to get the gear-ratio and speed combination. I have a spreadsheet kindly donated by syncropaddy apparently developed by Tim Smith in 1997 which for your numbers; standard gears, 205/80/16 tyres and 5.43 final drive gives me a speed of 95kph @ 3200 and 104kph @ 3500. This seems to be a big difference from your figures and I would like to be sure I am using the best resources possible to do these calculations.

Just for interest using the Tim Smith SS if I put a 0.7 4th gear and all other numbers as above I get 109kph @ 3000 and 115kph @3200. i hope I have not screwed this up but I have rechecked all the calculations and it seems good.

Would appreciate any further emlightment possible. Again thanks for wading in and helping.

[v-lux]

Hi,

I'm currently running a 1Z with a standard 5.43 diesel gearbox and 235/70/16 tyres.

With the current setup i'm seeing 60mph (satnav) at 3100rpm (cant be sure of rev counter accuracy). Performs brilliantly on motorways, loads of 'go' left in it at 60mph, will easily/eagerly shoot up to 70mph if asked/let to. Feels to me that there's plenty of torque left to turn some bigger gears, which is what i am planning on in the not so distant future. But i am going to stick with my 5.43 r&p as i feel going any lower it would make motorway hills problematic.

If it were me in your situation i think i would be trying to decide whether to sell the 6.16's to fund the whole project, or to keep them and possibly look at upping your tyre sizes even further to help with the gearing some more. (but that's another whole ball game )

As for the engine......my 1Z has a mechanical fuel pump, large injectors, high boost and a big chargecooler. Ive no idea what sort of figures its putting out as its never been on a rolling road. However i do know that it has MUCH more torque and is far more 'driveable' than any of the (many) AAZ's i had in my van previously coupled with the standard gearbox and 215/75/15 tyres.

It is a more expensive route to follow though, as it requires uprating the clutch and various other things, but all in all i'm very happy with it and glad i (eventually) went the extra distance and went TDi.

[syncropaddy]

But i am going to stick with my 5.43 r&p as i feel going any lower it would make motorway hills problematic.

You are correct and thats a mistake I made as I only have a good JX to push the van around but I reckon a good AAZ with a little intercooling will overcome it. I like to run light so Im not going the TDi route but a 1z has just turned up over here so I might investigate.

[andysimpson]

From what you want 90kph in a heavy syncro i think 5.43 would be best with a 0.70 4th gear, will still give good speed without over revving. a 4.86 with a 0.7 would make it not nice yot drive aroung your speed of 90 kph but would be better at higher speeds. MTDI is way to go, its only disadvantage is cost. its advantages over jx/aaz are much more low end torque, much better economy, none of the getting hot problems as with AAZ.

[syncrodoug]

Of course there's always the PD - how are you Andy? I trust you and yours are fine!
Doug

[syncropaddy]

Hello again,

Thanks for the figures. I would like to know what program you are using to get the gear-ratio and speed combination. I have a spreadsheet kindly donated by syncropaddy apparently developed by Tim Smith in 1997 which for your numbers; standard gears, 205/80/16 tyres and 5.43 final drive gives me a speed of 95kph @ 3200 and 104kph @ 3500. This seems to be a big difference from your figures and I would like to be sure I am using the best resources possible to do these calculations.

Just for interest using the Tim Smith SS if I put a 0.7 4th gear and all other numbers as above I get 109kph @ 3000 and 115kph @3200. i hope I have not screwed this up but I have rechecked all the calculations and it seems good.

Would appreciate any further emlightment possible. Again thanks for wading in and helping.

Yes you are correct. I was using a different sheet with a different set of ratios. I have all the gear box combinations worked out on a master Excel sheet and I was using that.
I feel if you use a 0.7 4th gear you will loose flexibility at lower revs particularly if you have a heavy van. I would look at fitting different wheels/tyre sizes.

[v-lux]

I would look at fitting different wheels/tyre sizes.

The only trouble with this is the massive can of worms you open once trying to fit oversize tyres.

I'm fairly well convinced that ive gone as large as i can possibly go with standard arches on a 14" van (235/70/16 or 225/75/16) This wouldn't have been possible without a suspension lift, wheels with a different ET, and a bit of grinder fettling on the rear swing arms.

I'm not sure how much bigger you could go on a 16"? There's certainly lots more room in the rear swing arms (can possibly accomodate 235/85/16 as standard?) however the fronts would not have room for this size i wouldnt have thought.
Even with the 'bit' cut off the arch i would estimate that perhaps 235/75/16 might be the largest you could go without any rubbing?

Can anyone with a 16" give some definitive figures? (as im just guessing here)

Anyway, it all mounts up to suspension mods, arch mods, different wheels, added stress etc etc etc. Which doesn't really fit in very well with the original brief

[lloydy]

Can anyone with a 16" give some definitive figures? (as im just guessing here)

Would be good to know what people are running, in combination with suspension lift, standard engine ect. As i'm looking at getting 215 70 16

[bigblue16]

I would look at fitting different wheels/tyre sizes.

The only trouble with this is the massive can of worms you open once trying to fit oversize tyres. (snip)

Can anyone with a 16" give some definitive figures? (as im just guessing here)

Anyway, it all mounts up to suspension mods, arch mods, different wheels, added stress etc etc etc. Which doesn't really fit in very well with the original brief

Thanks for that v-lux.

The original design brief was for the upgrade based on standard tyres; currently 195/75/16. I know that may sound a little wimpy to all you rufty tufty green lane offroad types but my original intention was to cruise Europe both west and east and possibly into Russia and maybe North and South America (hey you gotta dream) I might even get as far as Ireland? As someone said most of the world is now covered in tarmac with a few dirt roads, (my favourite). So I felt it was best to start the process with the standard wheel/tyre setup and if I can get a drive train with a bit of wiggle room then I can tinker with other tyre sizes down the track after I have evaluated the set-up. Also need to find out the most common tyre sizes available in my target holiday areas. I need to be able to match the existing set up or I will have to be purchasing 4 matching tyres everytime to prevent blowing up the VC.

cheers

[v-lux]

Probably best to try and match up with Toyota hilux tyre size then, he he.

[syncropaddy]

I would look at fitting different wheels/tyre sizes.

The only trouble with this is the massive can of worms you open once trying to fit oversize tyres. (snip)

Can anyone with a 16" give some definitive figures? (as im just guessing here)

Anyway, it all mounts up to suspension mods, arch mods, different wheels, added stress etc etc etc. Which doesn't really fit in very well with the original brief

The original design brief was for the upgrade based on standard tyres; currently 195/75/16. I know that may sound a little wimpy to all you rufty tufty green lane offroad types but my original intention was to cruise Europe both west and east and possibly into Russia and maybe North and South America (hey you gotta dream) I might even get as far as Ireland? As someone said most of the world is now covered in tarmac with a few dirt roads, (my favourite). So I felt it was best to start the process with the standard wheel/tyre setup and if I can get a drive train with a bit of wiggle room then I can tinker with other tyre sizes down the track after I have evaluated the set-up. Also need to find out the most common tyre sizes available in my target holiday areas. I need to be able to match the existing set up or I will have to be purchasing 4 matching tyres everytime to prevent blowing up the VC.

Thats an odd tyre size you have selected. Its 5% down on standard! v-lux's idea of Hi Lux tyre sizes actually makes a whole lot of sense if you get to go where you hope to. I selected a tyre size for my Syncro which seems odd and I dont think anyone else uses it. Its 225/70/15 and chosen because most 3 ton vans - Sprinters, Transits and the like use it as standard so its easy to get.

[v-lux]

As far as i can tell, one of the most popular sizes of 16" 4x4 tyre's seems to be 235/75/16. There's always loads of them for sale on ebay in that size that have come off of landrovers, hilux, mistubishi etc etc. (Think 235/85/16 is quite common on all the newer defenders and the like too)

If you end up going down the TDi route, if it were me i would get the tyres bigger. My engine pushes 235/70/16 along just fine, the AAZ didnt like it so much. Definitely feel there is enough torque to go even bigger, which of course your van being a 16" would allow quite easily.

Lloydy -
As has been said before, until you upgrade your engine, stick to tyres fairly close to the standard sizes. It'll be very sluggish and not too much fun to drive otherwise. Plus it'll be straining your JX further than it was designed for......and we all know what happens if you do that....

[lloydy]

Thats an odd tyre size you have selected. Its 5% down on standard!

Thats what mine wear at the moment, say's on the sticker in the door 195 16 and 205 16

[v-lux]

Thats what mine wear at the moment, say's on the sticker in the door 195 16 and 205 16

I'm sure i remember something from somewhere saying that if there is no profile mentioned on a tyre size ie 195/16 or 205/16 then it is an 80 profile.
This might be wrong...someone with more knowledge might have different info.

Which at a guess would be taller than a 215/70/16. That profile percentage makes a BIG difference.