Hello!!

And greetings from finland!! I got datsun 1200 coupe and i am going to put turbo in it, but what will be good and strong gearbox for it??

T;KImmo

Which motor are you putting the turbo to? And any gearbox that's been rebuilt for more power is always better in the long run!

A15 engine, i have a60 5-speed now but i dont think that will be strong i enought.

This gets discussed a lot and generally the two options it comes down to are this:

If you have the money, and can find one in good condition - the toyota t50 gearboxes are an option. Toyota boxes have a removeable bellhousing, and a local (Australian - so local to me at least!) company makes a conversion kit, which is mostly a new bellhousing to bolt on thee, and then a special clutch plate with toyota splines but a diameter to suit the a series. They also (*iirc) come with a gearbox yoke to suit a datsun tailshaft.

You'd still have to make stuff like a rear crossmember to support the new gearbox, amd of course you need to find a t series box in good condition (they are getting rarer here, not sure about other places)

The other option is the datsun 71 series boxes. They are strong enough for sure, but they don't have removable bellhousings, so you need to do a lot more work to fit them. basically you need to mount them on a steel pipe/bar (one that you make yourself) that fits tight into the crank/main tunnel of the engine block with the crank removed - that mounts the front gearbox 'snout' of the box at its other end - that lines up the engine and gearbox centrelines perfectly. then custom weld on a new front section to the bellhousing (you can cut one off a 56 or 60 series box and cut the 71 series bellhoousing and weld them together, or make custom new flat pieces and weld to the 71 box accordingly. You'd have to weld in the starter motor section.too.

Clutch wise - in this case you can actually get clutch plates for later model gearboxes that fit the diameter of the a-series (there's 3 different clutch plate diameters for L series engines, and one of them fits) but I'd suggest trying the 'middle' size. This would require you get the a15 flywheel drilled and tapped (and new dowels, and the surfaces machined to match) to suit the larger pressure plate but this middle size will fit on an a series flywheel, and the bigger diameter gives it more 'leverage' so for the same pressure it'll grip better). You have to heat up the bellhousings before welding or they will crack for sure when on the car.

What else - you need to take the input shaft out of the 71 series, and machine down the spigot (the finger at the front of the input shaft). It is so big on the 71 series boxes, that it won't fit inside the crank tail, even with a custom thin bush, so you need to grind it down to the a series box sizes (and you'll have to 'grind' it not machine it - what I mean is it is usually to hard to 'cut' on a lathe and you'll need to use a stone of some sort. It sounds very 'caveman' but I've actually done something like this by solid mounting a small 5 inch disc grinder on a lathe and turning shafts down that a cutting tip couldn't work on because the material was too hard (in this case it was a diff cross pin that I was adapting, and it had a similar surface hardness - I won't bore everyone with the details)

http://datsun1200.com/modules/myalbum/photo.php?lid=22569

http://datsun1200.com/modules/myalbum/photo.php?lid=22568

http://datsun1200.com/modules/myalbum/photo.php?lid=22570

http://datsun1200.com/modules/myalbum/photo.php?lid=22571

These are links to pics of the 'middle' sized L series motor clutch plate and pressure plate sitting on top of an a15 flywheel. It shows that the pressure plate will 'just' fit, and so you could re-drill, tap, and dowel the a15 flywheel to take this plate. The plate in the pics is not a standard one, it was behind the motor of an L16 powered rally car that was sold on this forum (long story short I ended up with some of the parts from it) so it's a non standard clutch plate, but it still shows the diamter.

apart from dowels and tapped threads, you also have to machine the flat parts of the flywheel to match up with the l series clutch plate. the a series has a slightly thicker raised sectionfor the clutch disc, you'd have to have it machined so that it had a full flat section in the new clutch plate area which is further outward.


OK, so that's the two main options used here. The strongest of the two would be (in my opinion) the 71b series (or a 71c i even stronger, but they tend to be a bit more expensive than 71b boxes) by a considerable margin. It is a lot more work, but sometimes that sort of work is no problem for a lot of people, and actually less trouble than trying to source a good toyota t50 box, and the cost of the conversion kit.

It is quite possible that where you are, different cars are more common, and a gearbox out of something else - I don't know maybe something like late 80s/early 90s volvo manual geaboxes are very cheap and there are plenty of spares - is what you could use.

There's at least one guy on this forum that is from Finland that has a turbo a series (and is rear wheel drive) - and another with a front wheel drive one also turbo. Have a look with the search function, you might find posts by them. I'll bet they could give better advice based on what boxes are practical to source in your region that will do the job.

63A box - ticks all the boxes! Hard to find but worth the effort as it's all a bolt in fix. Should be strong enough to cope with a turbo (and these are the key words for any transmission) if used with some care.

The 60 series 5 speed is stronger than you might think. Whack in the new set of bearings, and worry about it when it actually breaks.
I abused the bejesus out of a 60L box behind my supercharged motors for a good while and never broke it. I only onsold it because I found a 63A. (Which has actually given me more trouble than the 60 did) But most people have more mechanical sympathy than me.

The T50 toyota box has horrible ratios, 1st gear is non existent. For a modded bellhousing choice the 71 stumpy is the most available but the 60 series is plenty strong I agree, especially if there was a way to fit an oil cooler to it for endurance racing or some kind of sump attachment.

Interesting conversions to the GA16DE http://www.datman.co.uk/forum/viewtopic.php?f=12&t=5102

I would love a T5 with close ratio kit, to fit an A series you could use an auto bellhousing from an A series use a 5mm steel plate with 4 holes for the T5 to bolt on and tap the rest behind the A series Bellhousing. The T5 weighs 34kg in the long version and 32kg for the stumpy S-10 version. Almost as light as the T50 but close ratio gearsets are 1095 USD for any ratios. Would need front input shaft which is removable to be machined down to A series size and use a custom spline clutch plate. Auto bell needs hydro or cable clutch slave provisio. You can machine the bottom off box & use standard rear mount section where the green square in first pic or indicated with red line on bottom pic.

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I swear this is meant sincerely - have you driven a t5 box before D? They are a fairly agricultural shifting box, not good for quick shifts, and there's been a couple of threads on performance forums from people having trouble with brand new ones, and so forth - very noisy, rough imprecise shift. Don't get me wrong here, any half decent driver won't have any problem using one, but they aren't as smooth as some of the nissan/toyota boxes to shift gears.

The toyota ratios probably aren't fantastic, but with a turbo setup, you can have massive torque from the minute it spools, and it'll typically respond very well to pulling it down a few thousand rpms on the gearchanges, and if done quick enough it won't spool down too much during the shifts, so it'll pull hard with each gear being engaged.

It's certainly a lot of work, but I'd still make a strong case (pardon the pun) for the 71b boxes out of the series 3 bluebirds (or ca20 spec 71b boxes from elsewhere around the globe - ca20, not ca20det, which I think got the 71c? . I specify this box for the following reasons - hasn't been behind a ca20det so probably not thrashed as much (even though the 71c is undoubtably a better box) and also about the 'newest' of the 71b boxes, so has all the little improvements they made to them during their production run, and lastly probably cheaper to source (esp for Aussies) from the series 3 bluebird than a 71c would be, and cheaper (maybe) than earlier 71b boxes that saw use in z cars or whatever they were fitted to (I actually forget sorry)

Their ratios aren't perfect, but they aren't totally miserable either.

I admit, I'm currently banking on this conversion for my own car, but I did a fair bit of thinking and reading/talking before I made the choice. I'll certainly be the first to come back here and say I was mistaken if it doesn't work out, but I'm fairly optimistic about the conversion.

Ratios aren't important in this case is say, as being in Europe that also limits your 2nd hand parts market.

60 series should suffice short to mid term, but if you can get a Toyota box, then the kit from dellow is only a few clicks away

Steel case Celica box

More than enough and bellhousing available from Dellow