fwiw I agree. I've rebuilt more bw35/40/55s and 904/727 torqueflites than I can accurately count (and a good couple of dozen of various others, trimatics, ford c4/10 boxes and the like).

They are fantastic where you have a setup which has so much power you can't even remotely launch at full throttle (or with nitrous activated or whatever), they are reliable and consistent (as far as performance goes) - you don't have to 'get' each shift right like on a manual (esp the 2-3 or 4-5 shift or the 1-2 and 3-4 on a dogleg) - just push one click forward and you're there.

They certainly cost power (but on a high boost turbo 6 or big v8 or the like it's hardly a huge concern) but being able to precisely load them up on the start line, and launch with just the right amount of throttle/boost to suit the traction conditions is worth more than a tenth or two with the average driver (I mean the average driver at any drag race meet, who are likely a good distance above the 'average driver' if we take into account all the drivers on the road out there).

The other big deal is esp with non std cams. you'll have no power off the line with a stock convertor. It'll lug away until you get into the cam's rpm sweet spot, and by then the show is over. SO you run a looser convertor, and can launch a bit harder. Makes it run hot all the time on the street, but even IF that isn't a big concern on a track only setup, well that looser convertor also means FAR more slippage at higher rpm, so you lose some power, and also end up having higher rpm for any given diff gears. So then you have to either risk engine damage, or run taller diff gears so you go through hte traps at more sensible rpm, but then you have less torque multiplication with those taller diff gears, so the car doesn't accelerate quite as well.

THe other big deal is the ratio spread. Most 5 speeds out there have what you might call an 'ok' ratio spread for a racer on a tight budget. Not ideal, but we can't all afford to go to Albins (who by the way produce gears that are pretty much second to none - they really are tops, but they aren't cheap). But with an auto - esp a 3speed, the gear spread is a compromise. If you look at the US dino motor oriented boxes, you'll be lucky to get more than 2.5:1 or so for first, then a big jump to around 1.5 or so for second (the early th700 4sp has a low first gear which is why vn v6 commodores were pretty snappy off the line for what was a stock/production car in their day).

Put another way - they are the sort of ratio spread that with a hi-po small capacity 4 cylinder, will have it needing to rev way past it's peak power rpm, then yanked down to below it's powerband with each gear. It makes for a VERY unsatisfactory combination, even with a motor that would in fact perform great guns in manual guise.

What I'm trying to say here is that the loss in performance will be far more than it would initially seem even IF you already take into account the fact the power robbing issues of a torque convertor fronted auto..

When you get to the point you are making 800ft lbs or more (and plenty of drag cars out there do, believe it or not) of torque, you have so much torque that you don't need the torque multiplication of (relatively) low first gear. You sort of don't need first gear at all. In fact you could (in this hypothetical) take off in second, and still have to launch with care as it will still try and fry the tyres. And in those cases, you'll naturally see more people looking at the 2 speed powerglide (which is basically 1.7x or 1.8x : 1 first gear and a 1:1 top) - They are a strong box (and can be modded to be way stronger than standard) but the point is they don't 'need' the extra gears in those situations.

But this sort of thing is absolutely at the other end of the spectrum, a small capacity engine with a need for more or slightly closer spaced gear ratios, and less than an overabundance of power.

TO be completely fair and play devil's advocate, if someone wanted to fund an a series made to run a big supercharger and nitromethane (so likely the biggest power output an a-series would ever make, for however long it lasted) - then I think it could be made with a wide enough powerband and if for no other reason than consistency and predictability, I'd give an auto a go. It wouldn't be a jatco though. Taking nothing away from their attributes, they aren't cheap, and I could likely cobble together a trimatic with a 4cyl gemini (or toyota corona) convertor (albeit opened up and stengthened with a few things, including a v8 sprag) to do the job. It still wouldn't be perfect, but you'd have some justification for it at least.

FWIW I seem to recall one of the tilley's running a valiant circuit racer using a fully manualised torqueflite. Even with a (relatively) high torque slant motor, you'd still have to select the convertor very carefully, so that it launched ok, but also so engine braking, and transition back to full power was smoother than with a convertor too loose.

One of the guys on PF was running a very high output 2JZ based motor (I forget what in for the moment) he ran a toyota auto, that was considerably modified, but still had dramas with the mph not being where he felt it should have been. Went to the stage of modding the convertor/setup so that it would actually engage the lockup clutch in the convertor at full throttle at a certain rpm or speed (I forget which). It certainly helped, but I wouldn't be taking bets on how long the friction linings in the lockup convertor would last with that sort of punishment.

That's the thing though, a lot of the cars you see in magazines and the like have this or that transmission, and they run good times. But they likely see only a couple of hundred kms (tops) between teardowns. An example would be the modified trimatics. I wouldn't have too much trouble with one behind an a-series, hypothetically, but between a few of the people I know/mix with, some of the big name race spec trimatics won't even hold up in a street driven car that runs in the mid 12s. Fullsize HQ sedans and coupes and the like with v8s, so obviously not lightweights, but still. Just could not get them to hold together, and the specialists who sold the boxes just wanted more money to keep repairing with no real options left to improve longevity (th350s and 400s on the other hand, had no trouble in the same cars, and they are all running them now)

It's still not a dirt cheap option, but I strongly feel a 71b box out of a series 3 ca powered bluebird is about the best combo of price, vs likelihood of not being thrashed/damaged vs strength to cope with a very high output a series.

I have a manualised re jatco behind my sr20 with a sequential shifter, it was built by bms transmissions and all i can say is i will never put a manuel in a turbo car again (unless holinger sequential).

For starters you dont have to spool up the turbo between shifts = faster car (i don't care who says it isn't, i have driven both manual and manualised auto in the same car and engine setup)

also as for downshifting it works fine just like the manual.

Keep the box oil cool and you dramtically increase the autos life ( i run a thermoed fan oil cooler with -6 lines)

I have 4.56s in the rear and the car happily goes 170km plus i think 4800rpm have not gone faster (was on race track)

as for price you can spend up to $5000 for a fully built box to handle 600 700 hp, mine was about $2500 with cooler and lines + shifter, next thing is built converter around $600, also for around $1300 you can manualise a jatco.

Hope this clears some things up.

Thanks Jmach and Tommo for the comments guys, I would prefer a 71 series manual for some cases but with a supercharged A series in the cruiser vb10 I think the auto will be a nicer touch for such a light car. The Jatco is a good box, a bit beefier than I would like but no choice for now.

As for the T50!! - Its quite annoying it comes up in all my threads when I havent even mentioned it. Yes the T50 is a nice box for the street if you dont mind taking off in second!.

I agree John the alternative is a 71 box as Sikyne has done same price as a T50 in the end but better ratios, strength, availability and replacement cost not to mention Don knows them like his jellybeans.

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it doesn't really clear anything up. I'm trying to work out who you're agreeing with, D or those saying autos are no advantage even for drag racing unless you're running fairly big power??? how much power do you have/what times do you run? would be very interested to see your times for both the manual and manualised auto in the same car and engine setup (plus what that setup was - in terms of power anyway). But if you haven't gone faster than 170kph (106mph) its not sounding like a whole lot of power...

also trying to work out if you're agreeing with D that you can manualise a Jatco for $1300 or if you agree with me that's its a $3K job to build a manualised box for a car - because that's what you spent, $2500 plus $600 stall still to come

Its pretty clear that 1300 means 1300 for manualised kit fitted. I had my Jatco refreshened for 250 from Footscray auto and my trimatic refreshened with diff input shaft put in and for 200 from same place got quoted a 1000 inc above prices for full manualised kit and larger oil passages along with some other mods. If anyone needs an auto reco few places have been in business that long with trust from so many customers. They arent like panel beating shops prices that most other businesses seem to follow.

Im going for jatco auto for my supercharged A - cause the first gear of all the boxes mentioned besides the 71a are useless for the road and with the right stall a light body (640kg) Im going to have me some fun for drift and skids as per title. Yes fun! not trying to beat anyone with timeslip or ego trips just a setup that will handle the torque without me been frustrated that I need to take off on second. If I went back to my stroker one tonner Id still choose an auto with a stall but the 4 speed worked well but driving day in day out from place to place the auto allowed me to relax, take off nicely with one hand on my girls crutch.

The vid I posted was also for fun viewing and cause Im a big Baja and sandrail fan and sorry to throw off some peeps it was not the intention.

If you can get a cheap 60 series, t50 and are happy to take off on second for the street then by all means go for it but for budget over function an auto is what Im going for with a supercharged torquey A for kicks.

refreshened???

to be fair D, the title says good decision, not just for fun. But even so, I can't see a 3spd auto with 3.5 diff gears being any fun at all for drift with a supercharged A series.

1300 eh? so your planning to take a Jatco from the wrecker or under a bench somewhere and just manualise it for 1300 and job done eh? If so, that would make a manual even more of a better decision than an auto.

Also, your useless manual first gear argument is a bit silly. If you just fitted the taller diff you're planning to do for your auto, 1st would be an absolute necessity with a manual box.

I love autos for nice cruisey street cars, as long as they have enough grunt to drive them. And they have their place in specialised areas of motorsport, but I don't think a drift A series is one of them. Will be interested to see how it turns out though. When's the project start?

The title is clear "decision" you added the Good on your own. If you cannot understand or accept that I have taken a wreckers 60-80 dollar boxes and had them recoed refreshened or whatever it needed for the amounts listed in 2 occassions then all you have to stand on is that yes it could cost more and quite likely considering the market but good deals are still to be had if you know where and the shop still looks after a long time customer. Yes it can cost more but you must accept there are other possibilities beyond your personal dealings and ideas. Believe it or not I get great prices in the Footscray area from engine reconditioning services to auto transmission servicing and are well worth the freight instead of going to the pricey places you are used to your end.
I also have even cheaper engine reco services available from someone who does it at home in their time if you are not in a hurry.

I have fitted 3.9 to the rear of my old ute and my current wagon and are still useless with decent tyre unless I go stupid sizes that dont suit the car. So the only thing silly there is the lack of acceptance (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) on a 1200 a different story as big diameter is no problem but Im limited in a 1000. A 1000 with an a15 has useless first gear with either 60 or t50 period not silly just fact.

For me drift and skids dont have to be full time necessities of this build, I have most of the components, pulleys just working on manifold and blow off valve atm and as much as I would like a turbo setup, the SC is just simpler atm.
Everyone has their own idea of fun and also pricing hence we have forums.

If the superA is enjoyable with the manualised Jatco and can be controlled in power drifts, sliding and take offs then it will tick all my boxes. If not then Ill be the first to critically cut it up.

just found a guy who does the shift kits for the jatco for peanuts is someone a member there to get his details?

$150 changeover is better than 550 from shiftkits australia and 770 from Keas. He has the DIY dvd for $75 :)

Just would need stronger servo for mad hp otherwise stock should do with good cooling instead of the fan setup.

http://www.calaisturbo.com.au/showthread.php?t=234133

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are you sure?

My missus has a worked A15 auto, you should come over for a drive D to see what it's like,
(you can even simulate the power robbery of a supercharger by turning the air con on, jokes)

then maybe try the A14 manual rally car for comparison sake

I'm too lazy to look up the specific ratio's of the boxes being talked about here. But I've always found the spread of the 60L and my 63A to be quite plesant for most uses with my engine.

Interesting read Jmac.
I've not heard many good things about tri-magics. They dont sound much/any Better than the bw35's.

Given how understressed the Jatco's are, it shouldn't require a huge outlay to freshen up a used box. As I said earlier, the one I stripped last weekend was lke new in the clutches.
But from the one Auto A series car I've been for a ride in, (Albeit a bog stock a12, either four up, or drunk- or both) it did seem like there was a decent amount or power sappage.