[Tawatree]

Hi all, I'm in the middle of a coily build and I'm stuck on deciding my gearing. It's a 1996 coily with a 3sge beams from an altezza, Hilux axles and will have the silly coily stuff redone. I'm looking for some advice on both highway gearing and low range. The transmission is the A650e auto which comes from the altezza (3.357 first, 0.753 fifth). From what I've seen most g16 swaps sit at around 3-4k on the highway (130Nm peak torque at 4000rpm). The 3sge makes peak torque (216Nm) at 4800rpm and in an altezza sits around 2200ish. I'm thinking I should be aiming for 3000-3500 but after some advice. Cheers

[rpmwrx]

Sounds epic! Keen to see a build thread... What transfercase are you planning on running?

Try this out to calculate your gearing...
https://4lo.com/calc/gearratio.php

Also here's a vid from Dirt Lifestyle where he gets into some detail at the 9.00 minute mark of the video.
https://www.youtube.com/watch?v=2n2oDQEqQDg

Hope this helps.

[Tawatree]

Cheers, I'll have a watch. That's the calculator that I've been using, I'm more trying to figure out what numbers I'm trying to hit as far as highway rpm and crawl ratio in low. I haven't decided yet on a case but it's looking like a 1.3 case with high range reduction will work best. For sure there's gonna be a build thread, just gotta find the time.

[Gwagensteve]

I can’t see a reason to buzz the engine that high and you also need to think about the effect on lower gears if you gear the car that deep with a 0.73 overdrive. 1st and maybe even second will be pretty useless so you’ve just made the 5 speed a three speed in reality on the road.

I’d calculate for about 3k in 4th because it should pull ok st those revs and leave 5th for relaxed cruising.

You haven’t mentioned tyre size or use but you’ll want a crawl ratio around 60:1 as a guide.

However you don’t mention transfer case (and this doesn’t sound like an application for a sierra case) so I don’t know what’s really possible because high range is going to rely on diff gears if you’re using a case with a direct high range.

[Tawatree]

Cheers Steve, I'll do some calculations for that and see where it puts me in all the gears (I should've thought of that). Tire size is looking most likely to be 33s but I haven't fully made up my mind yet. It'll be somewhat daily driven and see the tracks once a month or so. I actually was thinking of trying a 1.3case and seeing if it holds up (let me know if this is completely pointless to try) but otherwise you are correct I would most likely adapt a Hilux transfer to the back of the auto and would need to find some diff gears. They currently have 4.11s in them but there are some higher options

[Brenno]

I'm running a similar setup and have the filtering following.

Ca18det
Re4 4 sp auto 2.79 first, .69 overdrive
4.9 tcase
4.11 diffs
32s

Which gives me 56:1 crawl.

I can comfortably cruise on highway at 3k and low range is great without being ridiculously low which is annoying when you want some speed in low for the inbetween sections of tracks.
224nm and 125kw(engine) but I've detuned to make only 80rwkw

I find this the best as you can compare between different options.https://www.grimmjeeper.com/gears.html

[Tawatree]

If I gear for 3k in 4th it puts 5th at 2260rpm which is pretty much dead on the altezza factory. I feel like I would need to be at a higher rpm for the extra rolling resistance and box shape of the zuk but maybe I'm wrong about that?
Cheers Brenno, I assume that's a 4.9 gear set in a 1.3 case? How well does the case hold up with the extra torque? Also how does it pull on the highway?

[Gwagensteve]

I've just thrown some numbers into Grimm Jeeper

I think a hilux transfer case with reduction gears in it and 4.88 gears in the diffs will be about right.

That gives about 2400rpm @ 100km/h in overdrive 5th and a 65:1 crawl.

Any combination I can come up with a Sierra transfer in there gears the car too low on the highway and results in excessive crawl ratio (or not low enough) A Sierra transfer won't reliably handle the HP and setting up the whole car to take one will compromise the build, locking you in to a compromise.

However, is there a tail shaft adapter to adapt the Altezza auto to a hilux transfer? Will the transfer case output position with the hilux case work with the rear driveshaft length? (as it's on the crank centreline) Generally, from what I've seen the transfer case gets all over the cab mount crossmember.

from what I recall the Altezza auto is pretty long.

[Brenno]

The case has held up so far with the torque and pulls great on the highway at 100km/h. It locks into the converter at 73km/h, as I have a programmable auto TCM and can choose where I like it to lock.

I think Gwagen is spot on with the Hilux case idea.

[Tawatree]

I'll probably have a look for a Hilux case then, or probably a surf case with the electronic engagement so that I don't have to worry about how far back the shifter will be. It is possible to purchase the tail shaft adapter but it's about 3k and I'm a machinist so I'll give it a go making my own. I'll check out the clearance for thecrossmember but it's got a body lift so if needed I can notch and lift the cross member. It might also be an issue finding 4.88 gears here (NZ) but it does seem the way to go. Cheers

[Gwagensteve]

A BL will help but you’ll really need to juggle with the angle of the engine/ gearbox/ transfer unit to get the rear output below the crossmember but not have a crazy front driveshaft angle.

You won’t want a surf case as these are chain drive and have poor ratios.
All petrol hiluxes for about 25 years had 4.88 diffs.

[Tawatree]

I see what you mean about the rear output, I didn't realize how much drop the Suzuki case gave. Now I'm not sure if I can make a Hilux case work at all, I'm going to have about 300mm of drop and a driveshaft length of about 600mm. And that's without any other lift I might gain when redoing the suspension. I would also have to cut out the original gbox mount which was working perfectly with the transmission currently.

[Gwagensteve]

Yeah, that's what I was concerned about. It's why whenever anyone suggests an unconventional motor the answer is always "with what gearbox" because that then involves the transfer case and then the rest of the car needs to get build around that. The motor is the easy bit.

A double overdrive/deep overdrive auto makes the gearing in a Sierra so much easier to solve but all that length has to go somewhere. The AW-4 with a vitara transfer adapter and Trail Tough bush is about a long as can fit and retain jackshaft function and keep the transfer in the stock spot. I don't know if an A-340 could be built with a vitara output shaft and transfer adapter to use the traltough closeout bush but then you could theoretically keep the stock transfer in the stock position with the BEAMS - you'd give up the extra ratio but the power of the 3SGE shouldn't require it. yes, you'd have a Sierra transfer still but if it's that or the project can't proceed ,maybe that's the best option.

Moving the output up to the crank centreline and moving it back at all really plays havoc with the rear driveshaft. Which then raises a whole new issue - the wheelbase of a Sierra severely limits how much traction the car can generate and therefore how well it can deploy the horsepower of that BEAMS engine. Adding wheelbase would make the whole car work better and would solve the rear driveshaft issue. I'd suggest with a 33 somewhere around 92-95" of wheelbase is probably the sweet spot, but as you can see, with (effectively) a hilux sized engine, hilux sized gearbox, hilux transfer, and hilux diffs and a requirement for a wheelbase pretty close to a SWB hilux (4runner) how much better is this project going to end up than starting with a hilux?

Sorry for a big existential dump but this is how guys end up in unfinished project hell. the G16B/AW-4 combination is common because it works and is relatively simple. adding another 100HP and everything that entails for the whole car is a very big step

[Brenno]

I didn't realise this was going in a SWB, sorry overlooked that.

It's going to be a very tight squeeze and the driveshaft is going to suffer.

There is a fella in the north of Tas who has a 7age/supercharged, hilux gearbox + transfer + diffs in a LWB and still factory WB of 93inch and seems to work ok.

I am running about 99 inch as I have pushed the rear axle back and my transfer rear output is sitting directly below the rear cab mounts.

[Tawatree]

I see what you mean, this is my first zuk and first project of this scale. It's all snowballed as you would expect. I at first didn't realize that coily diffs were different and much weaker so that led to different axles and Hilux is the cheapest easiest option here. Still loving it and it'll get back on the road whatever it takes. What would you say is the shortest functional jackshaft length? As a second part to that question has anybody ever (re-married?) mounted a sierra case to a gbox with a custom input/output shaft and adapter plates?

Also what's the go with lengthening the wheelbase on a swb wagon? I assume I could push the front axle forward maybe 3" and the rear a fair bit more but then would need to relocate the fuel tank too.
Cheers for all the help and advice so far, really helping to figure out the multitude of issues I'm encountering.

[Gwagensteve]

OK, I'm going to suggest you really take stock at this point before you end up forging ahead for too long and box yourself into a corner and lose motivation.

Coily diffs aren't "much weaker" than leaf diffs, it's just that the front diff is poorly supported by the aftermarket. it's very similar to the Jimny diff which is well supported and they can be swapped over pretty easily.
The other big issue with the SJ80 is the suspension. It has some very unfortunate quirks - hugely mismatched front and rear roll stiffness which makes them nasty off road, bushing bind, the front stud design that makes modification very difficult and short radius arms that are prone to bend. It was road biased suspension that only just matches the peformance of stock leaf suspension off road and is very problematic to improve. I"M not sure what your plans were around this.

These are old cars now and everything has been tried before. Brenno has built a really effective, well built and legal car, on hilux diffs.
I've been building sierras for many years. I don't like Hilux diffs despite knowing they're the "sensible" option, but I think building axle housings is fun and I'm not daunted by doing dumb things like pulling apart brand new airlockers and having the gears broached to suit Toyota splines.

I don't think mating the Sierra transfer directly to the gearbox is a good idea. Many people have tried this. The alignment is very difficult to achieve as there is no flat mounting face on the front of the transfer. The result is normally poor bearing life in the Sierra case. There is also nothing on the front of the case that's supposed to support the weight of the transfer hanging off the gearbox, so the whole mount arrangement becomes a bit of a nightmare. Of course anything is possible with enough time and effort but that's a lot of time and effort to put into a transfer that will be very marginal with a near 200HP engine and a lot of weight.

The shortest jackshaft? the longer the better. the shorter it gets the more critical the alignment, the more vibration, and the shorter the universal joint life. Again, people have tried guibo's and other misalignment joints but a very short shaft still puts lots of loading into the transfer. an inch or so of tube between the unis would be about as short as I'd like to go.

I don't think you'll get the front axle forward 3" with a 33" tyre. I'm 25mm forward with a 35" tyre but I've narrowed the front clip to match the taper of the bonnet, which frees up a lot of headlight room. This doesn't help the transfer/ driveshaft situation though.

Stretching the wheelbase is fairly easy by refabricating the rear of the chassis. It also allows compromises to be removed like the nasty taper and the too-far-inboard springs, but if you want to keep it a wagon that's a major job. but all this adds up to a massive build and you need to have a lot of skill and experience to understand what you're messing with when it comes to suspension and general fabrication, and you have to be very sure of what you want the car to achieve. The one great truth is that the more modified a Sierra is the less it's driven.

For reference, here's my chassis rebuild. My wheelbase is 100" to suit 35" tyres overall chassis length is the same as a stock LWB. my transfer is in the stock location as I have an AW-4 auto so I didn't need to move it. rear diff is back 6". Suspension is double triangulated 4 link, coils are Calmini 3.5" vitara rear, shocks are King 2.5" 12" travel. Fuel tank is custom made, about 35 litres.





My car is not engineer approved but I had an engineer up discussing another build and he was very happy with the chassis work and happy to approve it, so we're going to copy it on the new build.

[Gwagensteve]

I can't describe how stable and trustworthy this rear suspension is. The car aways launches dead straight. this is the 5th different rear suspension setup I've had on this car and it's outrageously better than radius arms and inboard springs, which I ran for a while many years ago on this car.

[Tawatree]

Okay so I guess I should lay out the current plans and see what falls apart.
Plans were to rebuild the silly suspension with Hilux axles, pajero radius arms and most likely Vitara coils, I really like the way you first implemented your radius arms with the triangulated geometry, but I need to check with an engineer here to see if it's allowed, otherwise I'll just run them straight and still gain the benefits of a longer, stronger arm (pin mounted which seems like it could help reduce bind?) and redoing the coily stuff. I don't think I want to go to the point of extending the chassis but I will try to push out the wheelbase ~slightly~ when doing the suspension. Tires will be between 31-33s just depending on what works well with the suspension.
The obvious stepping stone now is the transfer case setup.

I currently have 4" between the rear of the transmission and the flange of the t case (in stock location) I'm assuming I could just make that work for a jackshaft with a 1.3 case which I would have to brace and just see how it holds. Otherwise I can adapt the box to a Hilux transfer and find a balance of how far back the engine has to tilt to make everything work.

The ratios work better with the Hilux case as has been figured out but I think I can get a close enough for me solution with a 1.3case.

I should say that none of the cars I drive with have lockers or reduction gears (yet) so I'm not shooting for the perfect setup, just something that is fun to drive and I love a good project. This deffinately won't be the last iteration of this car either

[Brenno]

I don't have Hilux diffs Steve, just widetrack with airlockers, chromos/full float.

I kept mine fairly sensible. It's not the most flexible thing but it's still very capable offroad with the lockers but drives so nice onroad. I did 7000km during my last VHC trip and loved driving it. It needs to be a compromise between good on and off road I think.

[Gwagensteve]

Sorry, confused your car with Gricey’s (oops!)

4” isn’t enough room for 2 unis and any jackshaft.

[Tawatree]

Okay sweet. I think a reasonable next step then is to mock up the rear so that I can get a true axle position and see what I can make work with the angles. I would really prefer to use the Hilux case so I'll see what I can work out