Hi all It’s been a while since I’ve been on here properly but I thought you guys would be the best to speak to to help me work my new project out! I have a 1981 KE70 Corolla that I’ve had since 2007 but it’s been in hiding for 13 years!! (Yes I know lol). {} I now think it deserves to be reborn and I’m now set on putting a 1UZ from a Lexus LS400 into it! So set in fact I bought a 1995 LS400 and now have an engine ready. I have also recently bought a rear axle from a Toyota Hilux that has already been converted to fit the Corolla and has a disk brake conversion too…….. which is nice. (Thanks Nathan Rudd ). {} So now I’m at the stage on deciding on a gearbox and conversion kit to suit. I’m also being really picky as this car isn’t going to be a full drift car (sorry lol) but more of a fast road and weekend slider on the side. This means I want it to have good road manners but still be able to throw it sideways if I should feel like it . Now my rear axle currently has a 4.9 diff which is a bit short (or long I can remember which way round they are….. I’m new to this ). I’m looking at changing this for a “smaller” ratio so I can drive it at motorway speeds without it revving like mad!! Ive been offered a 3.7 semi locker which is going in the right direction. However, looking at gearbox options this is still a bit high. I believe the smallest Hilux diff is a 3.5 and have heard that the Toyota Century runs the same size 8” diff down to a 3.3…… but hard to find! Gearbox wise, the obvious choice would be a BMW one due to availability and cost. I’m looking at the 320d 6 speed box due to its compact size and plenty of strength to deal with an N/A v8. There are however 2 different types for the e46/early e90 and the later e90/e91 and am looking into which is best. I am however open to options but I have discounted the is200/RX8 options due to their lack of torque handling. W58 was another option but I’m hearing of difficulties with those too?! I’m Looking into which conversion kit to go for that doesn’t break the bank but is a good enough bit of kit. Ok I’ve said what I know but am open to options and hoping some of you guys can advise which direction to go in. It’s a bit of a minefield and I’m new to this level of modding so I’m working it out as I go. Sorry if I waffle on
Awesome choice with the 1uz. Ive converted and owned a Nissan S12 with 1uz and currently building a mk3 capri with a 1uz too. The s12 came to me with a bmw gearbox conversion, which is cheap and strong, but the ratio didnt match up to Nissan diffs at all and the aftermarket clutch was expensive and terrible quality. I swapped this out for an IS200 gearbox and adapter kit from lexibreak which worked great. The kit and gearbox were very affordable, allowed me good clutch options (MR2 clutch and flywheel) and made it perfect to match up to nissan gears (3.9 diff ratio). I did numerous drift days, track days and loads of road miles and the gearbox took all the abuse and was super cheap. I've since recycled the bmw gearbox conversion on my capri, but only because I could source a 2.8 ratio diff, and was happy with an oem clutch. The conversion kit it came with also isn't available anymore so replacement parts etc is more complicated. Given the low power of the 1uz and the light weight of the ke70 I wouldn't get too hung up on the strongest gearboxes. The is200 box is very compact so easy to fit in a small tunnel, they are cheap and readily available, and the conversion kit is well priced and proven. Hope this helps!
I was looking into these boxes and had quite a few people say they will do the trick, however, I had many more saying they destroyed multiple J160 boxes even in fairly mild tune road cars!! The J160 boxes are rated to 220NM and a stock 1UZ is rated to 366NM so it’s quite a lot over its rating! I can only gather that it’s pot luck if you get a good one that hangs in there or 10 failed boxes along the way! Personally I don’t want to take the risk of having many failures before I might get an ok one! I want to be confident in my build and that would make me nervous every time I took it for a drive! There is a fix for them but it’s expensive and need the box to be taken apart to do. {} As for gear ratios, there doesn’t seem to be much difference between the J160 box and the BMW 320d box. The J160 actually seems to be worse?! (If the info I have is correct?!). {} {} Yes I’m very confused! ♂️
I understand your concerns but I’ve seen people with BMWs strip gears at the track drifting with m50s which are sub 200bhp. Most failures are user error, high mileage or shock based rather than outright engine power. Same can be said for driveshafts! I’m not convinced those ratios are right, but I don’t have much experience of Diesel bmw boxes. The first 3 gears are wildly different though, which will affect drivability just as much as the cruising speed. Also 400rpm difference on the motorway is a surprising amount, especially with a big lazy v8. My s12 went from 4krpm at 70 to 3.4krpm at 70 when I changed boxes and the difference was night and day. if you can’t find gear ratio info reliably then go off the final drive diff ratio as that tells you immediately how close it’ll be. Is200 is 3.9 stock, and my 5 speed bmw box (330d I think?) used a 2.8 diff, so put a Japanese diff behind that and you know it’ll be shit! From experience I work on the basis that on average anything more than a 0.3 jump in final drive will effect the usability a lot on the road in a negative way. Since you already have a decent rear axle, don’t commit to an gearbox conversion that makes it too hard to get the gearing correct, you’ll regret it. An n/a 1uz and light car will work well with most oem stuff so just pick the one with the most suitable gearing and nice gear changes IMO Consider the restrictions of each box. Bmw boxes are short and fat so the tunnel might need modifying, they also have a rubber donut instead of slip yoke, which can be prone to failure if not aligned properly. You also need space on top for the shift linkage as the gear stick doesn’t go straight into the box. Is200 box is skinny but long, but it does have two options for gearstick positions and a nice shift. Clutch options are a factor too, Jap stuff you can normally get a nice cheap exedy or act paddle which will last and drive well, bmw stuff seems to be more custom and in my experience hard to get right unless you stick oem. the actual conversion kit is import too, you might pick a strong gearbox but if the pilot bearing/thrust bearing/clutch/flywheel setup isn’t well engineered or aligned it’ll be problematic. When I removed the bmw gearbox conversion from my s12 the clutch had only been on for 4K miles and was completely destroyed (CG motorsport paddle) as was the pilot bearing.
Thanks for that, defo food for thought. I will double check my sources for the ratios too. A bit more digging required but good to have an owner’s perspective Can I ask what sort of revs your S12 was like at motorway speeds with the J160 box and 3.9 Nissan diff? That’s not far off the setup I would have? The biggest difficulty with mine is that I’ll be running 14” wheels as I’m not a fan of Corollas with anything bigger! However I run 185/65/15 which is almost the same as a 225/40/17 so should be that different just because of small wheels!
hey man, what diff ratio did you finally choose? I too have a 1UZFE swapped Ke70. It goes quite well with 195/50 R15 + W58 gearbox and a 3.42 diff ratio. It's been like this for 3 yrs now . I guess I'm used to the power now so I want to try 3.727s CK
