I don't know D, one minute you're saying "A 3.7, 3.545 or 3.31 will be perfect behind a modded tricked 3n71 for most duties behind a boosted A"
Then when I suggest the same diff ratios would fix your complaint about 1st gear in a manual box, you turn around and say "a 3.7 would help but not easily had for a h150 and prob be as useful as a security attendant standing in front of 20 cent gum ball machine" - whatever that means...

you certainly do get good prices though. "Refreshens" for about the cost of a flush/service ;)

just to clear up some confusion, all im saying is for a turbo charged car, of any sort you should always try and run a manulised auto (again unless sequential manual) as the boost will always stay on plus its softer on the driveline you all know how weak datsun diffs are.

car has not been dynoed yet or raced proplerly im estimating it has around 190kw at the wheels with the setup (haltech boost, injectors blah blah blah basing this of mates cars and other set ups at the workshop i go to)

as for the speed 170 that was done on a race track though not racing i was playing around when i went out to a track day, i was there helping a friend with his car. (i only said this to give an idea of gearing and speed with rpm)

give me a couple of weeks and ill take it to the drags and see what it does (waiting on new diff center)

also for the comparisons with manual and auto, when i was comparing, it was against a mates car whos set up has not changed and my car was significantly quicker than it with the auto compared to the manual (as boost stay on because you dont have to keep spooling up every gear change)

as with the price you can build a manualised jatco $1300

mine was more as i have other things done inside the box.

ah, see when you said the same car, I thought you meant the same car. Not that your mate has the same type of car but in manual form with similar engine mods...

and that you mean you think its significantly faster either by the famously accurate seat-of-the-pants, or even worse by street racing, which proves absolutely nothing when it comes to drag racing... just about every street racer gets their heart broken at the drag strip...

and when you mentioned the race track, I thought you meant you had actually raced it...

my bad...

carry on with the good advice like "all im saying is for a turbo charged car, of any sort you should always try and run a manulised auto"

I'm going to focus more on bw and trimatic autos in this post. Each trans has its own idiosynchrasies, so the jatco or any other won't share identical issues, but it'll still have 'some' and therefore the general point about the costs and reliability/risks etc will apply. and it's important. This post will (surely) go off on several 'detours' along the way, as I try and fit in each point that comes to mind. I apologise for this in advance, but would likely have to spend a week or more re-organising it any better, so realistically can only ask that you put up with it 'as is'

For gearbox 'freshen ups' - I'll try and add some insight here. I've got a pretty reasonable hookup for parts (I'm not a huge customer, but I do end up there every month or two, rebuilding a trans for 'someone' - and I pay cash.

there are _indeed_ parts within autos that are specifically designed to be replaced. The friction linings - for clutch packs and bands. If they didn't wear out then the metal bits they 'grab' against would be torn up, so they are intended to be 'sacrificial' - and they last a few years/few hundred thousand kms (in std production car usage type arrangements, typically). so naturally they are replaced. Same goes for every seal/gasket inside the thing. Just common sense, and absolutely they don't last for ever, and it's the 'right' time to replace them when you replace everything else. That's the 'standard' deal, more or less.

To give you an approximate idea - rebuiding a bw auto 'costs' me about $150-200 in parts, depending on which bands I choose to go with (and allowing for a bit of inflation, as it has been a little while since the last one of them that I did).

HOWEVER - I still have to pay to get a convertor freshened up (only a tool would skip this step, as it'll guarantee shorter trans life, by a long way, and you'll note that some trans places, the really dodgy ones will skip this and that's part of how they get their price down) to go with the reco trans. Add approx $100 if you know people, and $200 or so if it has to have anything upgraded internally.

But if the one way clutch in the bw trans is buggered, I can try and pick the best of what spares I have (and to that end, anyone I do one for, for a valiant, I get them to source a s/hand bw51 out of an early ea from the wreckers, and use the sprag, and the main casing, and most f the internals out of that, as it's 20 years younger than the val trans, and put behind a less torquey motor (mostly) so it's a good idea - there's also other improvements to the casing and some internals that bw made over the years, so there's plenty of reason to go that way) Anyhoo - if I can't locate a good sprag, most of the suppliers I know can't get them, so it's a matter of finding someone with old stock (and more than a few places have long since scrapped any bw parts they had taking up space) and having to pay what they want for it.

Front pumps (basically the pump that is driven by the engine, via the torque convertor 'snout', that supplies high pressure trans fluid to all the parts (including the valvebody) to make it work) - well front pumps don't last forever. They start to wear 'grooves' in their enclosure and once the clearances get too wide, too much oil can 'escape' around them and available line pressure (esp at lower rpms) will be compromised, leading to potential slippage and trouble engaging gears (again esp at lower rpms). They aren't all that plentiful. Theoretically the casing could be machined to get rid of the gouges/grooves, but I haven't actually seen that done. A new front pump (if available at al) could add another $100 to the costs.

Suddenly, the cost (and this is for a very basic transmission really) has more than doubled. And that's to say nothing of the potential for other bits to need replacing. Kickdown cables don't last forever, and they aren't cheap even in s/hand form, from valiant places. There _is_ one still available (or was a couple of years back when I last needed one) from ford dealers, but you might have to wait, not all would have it in stock.) that can be pretty easily adapted (and is the go for non standard carbs too, since it is a bit longer, so has more potential to be adapted to various apps)

Yet there are (or at least were) places that were offering change over bw 3sp autos for not much more (if at all more) than I could get parts from. Well, as it happens, I've had one of these transmissions in a valiant (it was one of the reasons I cracked the sads and decided to build them myself from then on). Anyhoo, on the front and rear clutch packs in a bw auto, you can have anywhere from 3 to 5 friction plates per clutch pack. Naturally a 4cyl (say a hillman or something) could get away with 3. But the hemis (and slants) fitted with bw35s all had 5, and frankly needed more. The bw auto is a decent enough thing for the time it was made, and was reliable enough and user friendly to work on but it should NEVER have been put behind torquey sixes, NEVER. Anyhoo, this bw that was from so and so autos, well when it failed inside 12 months (and their warranty was about as genuine as an election promise, if you get my drift) I pulled it apart, and lo and behold, the tightwads had fitted the thick spacers, so they only had to pay for 3 friction plates per clutch pack. KNOWING FULL WELL it was for a hemi. They also 'forgot' to tighten the governor and it came loose and wouldn't shift out of first, lucky I caught that early on (and put it down to 'one of those rare things). Lucky it didn't chew out the extension housing in the process. So I sorted that, crossed fingers, and as I mentioned, it didn't even last the year out.

They also used relined bands. Some people 'rave' about kevlar linings. I'm on the fence (as pertains to bw autos at least). There's a couple of issues. They used 'regular' relined ones. The problem with that is that it's fairly common for a bw auto to crack and eventually break the lo/reverse band, so it'll still work in drive through all forward gears, but if you select first, there's no engine braking (first still works in the forward direction thanks to the one way clutch) and reverse doesn't work. So the bands themselves don't last forever, so 'relining' one means one that has already seen duty in a car, so will be closer to snapping. So no way I'd choose a relined band.

Then there's the kevlar linings. Well hypothetically if you got a brand new band and had hte lining carefully removed then lined with the kevlar material, it might work. BUT here's the next thing - the shock of engaging the band in the first place (when you select reverse, that slight jolt, or if you manually select first and floor it so it kicks down (it will kick down at a higher road speed with 1st also selected than when in drive). well that jolt can not only break the band, it can rip the actuating servo (the thing that levers onto the band and causes it to clamp/engage) so hard that it cracks the casing and breaks free (and then it compromises oil pathways and will no longer engage irrespective of being 'broken free'). SO, the point is, the kevlar can actually worsen things, and the slightly less aggressively engaging regular (brand new) band linings are actually a better bet.

Then you come to shift kits. CErtainly you can sharpen up the shifts a bit, and less slippage occurs so less wear to the friction linings. Generally a good thing. But you can actually get to the point (quicker than you would believe) where the sharper shifts are sharp and sudden enough that the shock loading to the trans internals actually breaks things. And there's no point in 'reducing' friction lining wear rates if you break the bloody thing in a few weeks or months and have to rebuild, often starting from scratch. This is _particularly_ an issue on trimatics and the bw autos. If you run a trimatic with harsh shifts, and try and street drive it regularly, if you can get a month out of it, you are (no kidding) obviously driving it so gently that there was no need for a shift kit (or an upgraded motor) in the first place :). I'm hardly alone in figuring this out, I'm aware of a few people with similar experiences, and we've all made the trimatics last 'okish' behind mild 253s and the like, by avoiding an aggressive valve body setup that shifts too harshly.

If that wasn't enough there is YET another issue. It depends heavily on the specific transmission design and the valve body re-working specifics (not all trans places would do it identically, the end result would work the same, but sometimes they have their own methods to get there) - anyway - on a fully manualised auto, the governor (which is on the output shaft inside the extension housing) is no longer required 'as such' . It'll still be there, it just isn't needed (since its function was to allow 1 (or maybe more) valves to be open/shut by centrifugal force, as the output shaft rpm increases or decreases. It's like the 'sensor' that interprets road speed and influences shift rpm points). WELL, if this is no longer used (in the fully manualised valve body 'we' make the shifts happen when we choose them to happen) - then in some instances there is no longer trans fluid going to the governor itself at all. won't affect shifts BUT the oil going through there is 'flung' off the output shaft, and it is a percentage of this fluid that ends up then finding its way to the bush in the extension housing (that the tailshaft yoke slides iside of) This bush stabilises the output shaft/tailshaft front yoke. And without a little bit of fluid, it'll wear out the bush, start leaking, or (eventually) lead to some sort of breakage or failure as it disintegrates. Now I honestly don't know which (if any) fully manualised shift kits stop all flow to/into the governor - at least as far as the jatco goes, but if ANY of them do, the for a hillclimb/circuit car (hypothetical one) you'd want to check/replace the bush every race meet. On a dedicated drag car (assuming you smeared grease on the yoke before sliding it in) it'd last any race meet, and perhaps re-grease each race meet. BUT it'd be a disaster on a streeter.

Now if this _does_ happen to be the case with a jatco, the valve body could likely be modded to redirect some flow to/through the governor, or alteratively, you could tap into a high pressure passageway in the trans or valvebody itself, and run a brake line sort of pipe to the rear (you could even braze the end of the pipe closed, then use a tiny drill bit and drill it to make a jet to direct a (relatively thin/minor) spray of oil to the extension housing bush. All doable, for sure, but worth mentioning, since it's more time and parts costs into the equation.

The trimatics themselves also had different numbers of friction plates depending on whether or not it was for a 4cyl 6cyl or V8. To do it 'easily' the trick for warm 6s was simply to run the spacer(s) from the v8 ones and therefore fit the v8 amount of friction plates per clutch pack. When I was an apprentice and at trade school (batman tafe in coburg if anyone cares) a couple of the teachers in the trans section (in second and third year there were separate classrooms (if you could call em that) for various sections, from electrical, to drivetrain, etc etc) or modules to do) Anyway a couple of the teachers there were transmission experts, and they took the time to go beyond the standard info, and they showed us how for things like holden 6 or v8 powered mobile homes or work utes, they would machine down the spacer and piston in each clutch pack, and that would allow you to fit even more friction plates per clutch pack, which translated into longer life, and better reliability, for towing etc.

This sort of work isn't hard for anyone with a bit of experience with a lathe, but it still means you _need_ a lathe or access to one, and the time it takes to get it right.

Similarly, there are 'special tools' needed to install certain parts or measure/preset various clearances and the like. I don't 'own' any per se. I have certainly _made_ a few (and I used to be able to borrow a front pump alignment tool for trimatics from a local place quite affordably).. So I can get the job done.

But where I'm going with all this is just how much more there is in terms of time, labour charges, special tools, the possibility of things being broken above and beyond the normal parts you'd replace during a reco. And that's for me working from home (if someone asked me to do a bw auto, I'd want around $500-600 depending on whether they supplied a ford bw trans) and then you'd add on the money for a freshened convertor, and then it'd be a must for the biggest trans oil cooler they could afford or could physically fit (excess heat will spell distaster - as when the oil 'goes off' that much quicker it no longer protects parts like it should. Then there's the oil itself. The newest dexron spec is vi last time I checked, and it is supposed to be backwards compatible with earlier dexrons (so if your auto needed dex ii or dex iii, hte latest should work just as well. BUT it is a litte thinner. It also has different additives to suit modern autos and as such, I'm not 100% sure it's the most ideal for the bw35 type auto So an earlier fluid spec is probably worth a look. There's good and bad out there I guess, but the thing is you are looking at close to $100 for a couple of containers of 'quality' transmission fluid. So these "hidden" prices are pushing the 'real world' total up all the time. Mind you, I list that price as an approximate, for a relatively less complicated auto, and getting parts at relatively bargain prices, and (again) I don't have a factory lease to have to pay etc, so my overheads are hardly in the same league, so to speak.

Shifters themselves - to run a full manual auto, you 'can' get away with a stock shifter but you have to be darn careful about upshifts, or you can end up in neutral by accident and over - rev the engine. It's unlikely you'd get it into reverse (unless the detent/gate setup was worn badly on the shfiter.. But realistically, you're going to be far better off with a ratchet type shifter (any of the aftermarket ones - b&m hurst or whatever). no matter how hard to shove the shifter it'll only go one click, and engage the next gear, you have to release it, letting it spring back to the centre, then hit it again for the next upshift (and likewise for reverse). You might get lucky and find one second hand (but would either need to buy, or in some cases make your own, linkage/brackets to suit the auto trans in question) - but new- including cable and brackets, that can easily run you another $300 - $400

With regard to shift kits - I don't know him on a personal basis - but years ago I did have a bit of contact with (heck was his name mark or paul, I forget sorry) the guy from KEAS. He may not be cheap, but from my experiences, he certainly knows stuff, and I'd suggest that a shift kit through them would be a decent option. Some f the expensive guys out there are still snakes, but I'd go the flipside and say that, below a certain price level, nobody in the world could produce a 'true' full rebuild, they have to be saving the money 'somehow' and 'somewhere'. So basically the 'go' would be to stick to those who have a great rep AND that charge a little bit more than some bargain basement prices. To that end, one of the places I'd give a good rap is 'jim walton' in waterdale rd heidelberg. For the last decade plus I have done my own autos, but could come up with a list of people longer than my arm who have had first class top shelf results from Jim Walton Automatics.

What else? Oil supply. On the transmision, there will be a 'pickup' point (a bit like the oil pickup from an engine) where it sucks the fluid up from. rather than a pickup pipe on an engine though, usually it's just a mesh screen that attaches to or is a cast in part of the valve body. Sometimes it is positioned centrally, sometimes to the front, sometimes the rear. For normal duties, that's fine. But on a really hard accelerating car, the fluid will run rearwards in the pan, and could theoretically uncover the pickup and you loose oil pressure. It might not be for long, but it could mean the clutch packs - for a split second - lose clamping force and induce slippage/wear/damage.. To that end, in bw autos, the later ford mesh screens had a new 'body' that 'shifted' or routed the pickup point more rearward.[ All good so far. But during a massively hard corner (drifting perhaps) it could uncover it sideways.

A bit like 4 barrel carbs (for example the chrysler hemi e34 pacer had a brilliant intake manifold - big long runners, great design, and a 4 barrel carter mounted 'sideways' . Great in a straight line, but during corners, it could uncover 1 pair of jets (the 2 left ones during a hard left corner, the 2 right ones in a hard right corner) and it'd splutter. End result was that in 'std' guise, this compromised cornering was so significant that hte 2 barrel pacer were as quick or quicker on a circuit (despite being way too small for the combo). With a holley, mounted similarly, the same would occur. With a holley mounted 'the original' way (with primaries to the front, and secondarys to the rear) It would be fine during corners, but under hard acceleration (or with some other hypothetical car with 4 barrel holley, one that launches much harder) - the fuel sloshes rearward and uncovers the jets in the secondary side of the carb. So it'd splutter and stumble. There is a way around that, 'jet extensions' - tubes that fit snugly over the jets and extend rearward so the secondaries take their fuel from near the back of the fuel bowl. So now the car is fine under hard acceleration, fine around corners, but under hard braking it can uncover the primary jets as fuel sloshes forward. This isn't actually a big concern, since under hard braking, the engine doesn't 'need' to be operating at full smoothness, and by the time you ease off the brakes, the fuel levels out and the primary has fuel flowing as soon as it is needed.

Now the point of all that is that even with a well designed setup, you'll probably find that you can get acceptable oil pickup and no starvation in 3 out of 4 directions/g forces. Probably. But if you don't (esp if you get oil starvation going sideways) you'll see trans damage if you subject it to these sort of g-forces for sustained periods of time. But let's pretend you have managed to get 3 out of 4. That will STILL leave oil starvation (potentially) under hard braking. On a circuit car (and maybe a drift car) this won't be good. It'll affect all trans internals And if it gets low enough oil pressure that the clutch packs no longer grip fully when they are supposed to be engaged, well it'll shread the friction linings pretty darn quickly.

The next related issue is engine braking at all. If it is fully manualised, then presumably line pressure is max at all times, and shifts will be solid (as will be clutch pack application force or grip. But on non manualised ones, you can gear down and to engine braking, but the valve bodies (typically) reduce line pressure at lower engine outputs (which they sense either via throttle/kicdown cable, kickdown switch and or intake manifold vacuum) for gentler shifts for cruise conditions. So if you manually shift down in a non manualised auto, and then have zero accelerator input, it will experience engine braking, but with low line pressures, so the risk of slippage/accelerated wear and tear. So depending on specific design/valvebody, engine braking can massively speed up wear and hence reduce trans life.

Add to that that the convertor itself will (of necessity) be loose enough for decent launches, which will simultaneously be poorer for engine braking (and they aren't fantastic even with a tight convertor.

Enough rambling from me. I hope some of it is of use to someone out there :0

good for slush box not decision! the jury is still out.
A comma would have made a difference!.

I didnt get my convertor recoed so that helped the price for sure! forgot to mention that in the pricing.

===quote Harry===
I don't know D, one minute you're saying "A 3.7, 3.545 or 3.31 will be perfect behind a modded tricked 3n71 for most duties behind a boosted A"
Then when I suggest the same diff ratios would fix your complaint about 1st gear in a manual box, you turn around and say "a 3.7 would help but not easily had for a h150 and prob be as useful as a security attendant standing in front of 20 cent gum ball machine" - whatever that means...===

I thought it would be pretty clear .2 is not going to make squat just like a guard in front or a 20c candy dispenser

Basically 1st gear on a 60 series or t50 with a 3.9 or 3.7 on a 1000 is useles hence I dont care for either or recommend them for a thouee. For a 1200 would prefer a 71 series box with better ratios than a t50 as the 71 is a better box newer stronger cheaper easier to find and shift kits available cheap for the C version. Even the Toyota peeps upgrade their T50 to a W series bellhousing which costs 500aud for the bell and heaps keep buying them when a group buy comes up as the T50 self destructs behind boosted K series (A series competitor with round ports).
That in itself says that the W5x series another rare box is still preferred over a T50 from the Toyota K enthusiasts as it at least has more parts available and still easier to source for a rewarding result. The W series is 5kg heavier than the T50 and loads better in everyway if not better than a 71C CA and SR boxes its definitely its equal.

The jatco is around 2.6 first which is a big difference to 3.5 and in a heavier 1200 or late sunny it wouldnt me my choice to run an auto unless behind a bigger or hp capable donk.

I never used first gear behind a stock a14 or a15 with a 56a, 60a or t50 tudor and ute it was useless.

Even my vb10 can take off from 2nd gear with ease behind a stockish A12 and 3.9 rear with bigger diameter than stock rollers. Is that crystal clear yet?

A Jatco in a 1000 I hope will be easier to take off as the same setup in a heavier 1200 would definitely warrant first gear (again which is useless in a thouee) as its very necessary in a porky 1200 (especially with aircon and what I last remember where alloy wheels that are much larger rolling diameter and way porkier than original steelies / rubber etc)

Ive got 4 jatcos here so will see how I go, first gotta pull out the valve body should take around 1.5 hours and definitely the most annoying part of the build and then send it to R30X on the Calais forum for the mods.

Now is some Bogon here a member over there? ;)
At least alot of them have a Nissan donk in them.

The title, and especially the first post confuse me as i have no idea what the aim of the thread was, but it doesnt matter

do you plan to build this for drift and skids or something else?

and why im really posting is to ask why you focus on the weight difference, i mean why do you say the 1000 is more suited to an auto as it is lighter? is that soley becuase you need less torque and that suits the ratios better? or is that because the lighter weight will mean you need less torque which makes up for the fact you are losing it in the transmission, therefore putting it in a 1000 makes it equal to a manual in a 1200 or something like that?

To put some math to it:
The difference in torque from first to second in the a-series 4-speed manual is 73% more (in first gear)

SO you are suggesting that a 1200 requires 73% more torque to leave a set of traffic lights than a 1000.... (if it has 13 inch wheels with lower profile tyres instead of 12 inch and air con thats switched off its probably more like 250%)

take note the 1200 weight is at worst 15% more than that of the 1000

Not sure the percentages are right but I find a normal factory auto pretty boring and easily 20% slower than a manual. This is a different story with a tricked out Auto but it all makes sense with 15% less weight and an engine that produces 50% per cent more torque than an A10.

On a side note in case someone is interested there is supposedly a rust free sunny coupe 1980 model with an a12 auto all receipts, new yokohama tyres on original steelies, all receipts under the seats with books done 324,000klms and only has rust bubbles on doors and front guards have a little damage but its a beautiful metallic kakhi green with no rust at all anywhere else previously one owner judging by condition and receipts. Its at centre road wreckers and my buddy almost got divorced for asking the wife for its adoption.

Imagine 324,000kms with an auto a12 in a 900kg car with engine in good order and only there due to guards on both sides damaged due to old fella most likely trying to slowly undertake another car and getting wedged between it and a parked car and then letting insurance cover the 2 cars.

I wish I could get it for a legal ca18det conversion ;(

I work for a transmission supply company
I'll happily let you know what parts you can get and what they cost to do up a Jatco

And I've never had to take off in 2nd gear with my T50 with A15 , 185/60/13 and 4.11 gears

Now havng said all that
My guy who prepares my racecars would like to do a boosted A14 (square engine) with an auto behind it for hillclimbs
However he suggests we have the manual box for use in sprints and other events

what spec was your A15?

On my stock A15 with 4.11 rear was worse than useless on my kb10 with a 60L series 5 speed. Once I bored it out to 1608cc it was worse then with camshaft, head work, quad carbs, headers, lighter fly/clutch and ignition it was perfect as it had nothing below 2.5-3k. Back then I was a 68kg triathlon junky.

On my T50 A15 stock engined combos I was way happier in second.

I've owned a 1000 coupe with A14, 120Y 4spd, 4.1 diff and 155SR12. 1st gear wasn't useless in that (3.513 vs T50 3.587 - that's less than half the % difference than 3.7 vs 3.9 diffs which you say meant squat, so this is about half of squat).

2nd gear (2.02 T50) would be stupidly tall and useless for starts. Even ~400kg race cars running lower diffs and smaller tyres than your 1000 dont go that extreme with 1st gear!