weaklink

what about a 350 setup for the street?

turbostreetfighter

as long as you get the right convertor you will love it. the trans brake is awesome, you never have to worry about launching the car.

MWW

LUV94RX7

iTrader: (3)

I sent you a PM.

Ken

mad20b

Sorry to drag this up from the dead ( I guess thats what happens when you do a search for drag racing trans ) I have just spoken to Al @ Als race glides in Oz. He does a lot of the racing rotaries over there & suggested either a C4 if I use nos to spool it up or a Powerglide..... I was ringing him to get a TH400 setup.... He strongly suggested that was the last trans I use for a rotary.

Rice, What did you end up doing??

kabooski

20B and a strong auto

Thats my dream

I wonder why Ari Yallon never went 20B and auto to race in Nopi

razorback

what about the dodge 727 torqueflite?

peejay

TorqueFlites suck ***. There's a reason why Mopar guys start burnouts in 2nd gear, then shift to 3rd right away... they don't want to risk grenading the trans.

C4's were installled in damned near everything. They make good swap transmissions because unlike most other American automatics, they have separate bellhousings. They can be beffed up really well - pretty much nobody runs C6's anymore because the C4 can accelerate faster and be just as strong. Well, nobody running small blocks - I don't know of any way to mount a C4 behind a big block. Might be by now but I've never seen it - Ford only put C6s behind both types of big-block (FE and 385 series). Also AFAIK Ford only put C6s in the truck line.

Ratios are Standard US Automatic ratios... 2.45 / 1.45 / 1.0 give or take a few hundredths. The only trans I know that deviates from this (besides the 2-speed units) is the TH700R4, which has much wider gear spacing.

wwilliam54

c4 is about the best auto tranny made IMHO
easy to find, and cheap to biuld up strong
pretty easy to work on too

razorback

ive always heard that torqueflites are good??

im talking about the late 60s versions of the torqueflites.

peejay

They're fairly beefy (and a 727 for the most part is a 727 whether it's behind a 440 or a taxicab Slant 6) BUT! in RACING situations, the 1-2 shift can cause... aw hell it's been years since I was paying attention, but in a nutshell there's a specific part that has to reverse rotation on the 1-2 shift, and it can shear (the sprag?) loose from the case and at that point it starts rotating at roughly 3x engine speed. WHAM! Shrapnel everywhere, hope you have a good ballistic blanket.

There ARE specific modifications that can be done to REDUCE the risk. The only SURE way is the way I described above: Avoid using 1st gear for burnouts!

The C4 is not "perfect" either, granted. But it doesn't do as many scary things as the TorqueFlite.

Maxthe7man

I will disagree with the commentary on the 727. I have had them behind both small blocks and big blocks and never had such problems...Its one of the toughest auto trannies every built, if they can handle 440 6 packs and 426 hemi's, it'll handle a 13b, way way way tougher than a c4, but way way way heavier to...Alot of the wives tales about the 727 came from amc racers who's 998 torquelfite was a 727 case with 904 internals...The 904 was for lo po small blocks, when the 998 found its way behind a 360.390,401 amc, bad things happened...
But thats all pretty old school ****, and I truly wouldn't waste my time with any of that stuff, there are much better 4 spd auto's out there now, with all the improvemnets built into them from the facotry, that you would have to do to a older 3spd trans...
Running a 4spd auto gives you the ability to run a wickedly low rear end ratio, but still keep it liveable should you run it on the street...
My pick would be a Hughes prepped 4l60e or 4l80e.. A friend of mine is abusing one behind a zz572 crate with no problems, the nice thing is being able to run a 4.56 on the street and still having really decent cruise rpm..Max

peejay

Just because it can handle the TORQUE doesn't mean it can handle the RPM!

When you shift from 1 to 2 at 6500rpm doing a burnout (where drivetrain acceleration is much more rapid than powering down the strip) that trans is going to scream "Oh No!".

numan2

hrmm....I could have fun here but I'll enlighten you a bit.

1) torqueflight trannys have a issue with the low roller clutch. the way the cam is anchored to the case is very weak BUT it can be fixed to hold just fine. They also don't have as much support for the rotating assembly as the GM or Ford units therefore they wouldn't do well in high rpm aplications like behind a rotary.

2) C4/C6 you can rule out the C6 due to weight and heavy rotating mass but it is a very strong unit. The C4 however can take quite a bit of abuse. It has good bushiing support, decent sized clutch packs and strong planets BUT alot of the losses in these units are due to thrust washer drag and band overlap (the time the band is applying/relasing and other friction elements are applied at the same time). Also the overlap problem affects the quickness of the shift. The C4 would make a durable light weight unit and should hold just fine on a rotary.

3) 350/400 The 400 is a extremely strong unit but like the C6 is very heavy and has a hefty rotating mass (heavy drums and planets) but is more compact than a C6 and has a closer gear ratio than the others. The 350 is somewhat larger than a C4 and has a rotating mass higher than a C4 and less than a 400 but where the 350 shows it benefits are in it has excelent bushing support, depending on the year it was made they had full torrington bearing thrust surfaces. Also the 350/400 tranny's don't have the overlap issue that the C4/C6 and TF units have because the band in them isn't used in a upshifting gear the band is strictly for grade engine breaking. The 350/400 also has much quicker shifts because there is no timing issues because of band/clutch timing.

So in short C4 is light and decently strong but you'll trade some performance because of clutch/band timing and washer drag.

the 350 will handle the RPM better and wear less and provide faster shifts but there is a weight penelty for it.

As for my qualifications I'm a master transmission rebuilder with over 25 years experiance building high performance transmissions and have been racing rotaries for 15 of those years.

Maxthe7man

The rev limiter on my old small block setup was 8000 rpm, I came out of the burnout box everytime with it tapping off the rev limiter... No such failure....All that 727 had was a transgo shift kit and a 4500 rpm stall, the rest was supplied by the local junkyard from a 2wd ramcharger....Its funny I used a 727 for years with no such problem, you would have though it would have shown up for sure in one of my old 4x4's when I came screaming out of a mud hole with it doing the 1-2 shift, its a problem I have honestly never heard of, and I have owned my fair share of mopars..Now I just run a 4spd in my current mopar... I kinda like rowing my own now..

Just gonna add, the other thing to look at is the gear sets, I know there is a deeper gear set available for the mopar trannies, and thats something to look at on a small displacement motor..Max

numan2

usually the problem on the TF's came when a drag car would come out of the burnout box in 2nd gear and with hot sticky tires tried to do a burnout in 2nd. or 3rd. if you were using manual 1st. you were ok because you have the low/reverse band holding tsking the load off the roller clutch. The power flow in the TF's in drive 1st. gear is forward clutches and low roller clutch. in manual low it's forward clutches, low roller clutch and low/reverse band. If you ever get a chance to see one apart you'll see what I mean about it.