42rh for drag week build? Gasser Barracuda

[Budget mopar guy]

To start off with thanks everybody for answering all the transmission questions lately. The background of this is a building my barracuda Gasser currently. The main reason I’m building the car is eventually to take on drag week. I was originally going to put a four speed in my car and then I started thinking that driving it on the highway would probably be absolutely miserable for hours at a time. In reality if I actually wanna do this drag week thing I really should consider a transmission with overdrive. I had considered an AX 15 transmission, which is a five speed that was found in Dakotas, but members on here have said that it won’t hold up to drag racing. I need to build this car on a budget and I am pretty innovative and determined. I don’t care about cutting transmission, tunnels, or fabrication work. I can do all that. I have been reading and reading and reading about the 42RH transmissions. Essentially they were the 904 based for speed transmissions found in Dakota is and llight duty trucks. It appears that in the very early 90s they made non-lockup versions of these transmissions. I believe some of the 46RH transmissions were also non-lock up. Please correct me if I’m wrong on any of this. My question is on these transmissions how well would they do with racing? For the non-lock up versions do the 904 and 727 converters work in them.? Are manual valve bodies readily available for them and overall is this a fairly budget oriented option if I rebuild a transmission myself. I’ve looked at how people actuate the fourth gear and to be honest I would be fine with just flipping a switch on the dashboard rather than running the pressure switch like a lot of people do. I really just need that fourth gear for that highway, cruising from track the track. Also if I were to race the 42RH what kind of internal upgrades do I need to do to make this thing hold up?

 

[junkyardhero]

there is nothing budget about building an OD automatic for drag racing purposes.

bust open your wallet and be ready to cry. and then cry some more when you have to get the converter redone because you didn't get it right the first time.

personally, i don't think i'd even use a 42 or 46 for something like this. 200-4R would be my weapon of choice.

 

[Budget mopar guy]

I’d even do the 46re for cost effectiveness. I mean the Dakota guys run these style transmissions and they’re making it work.

My engine will be a 360 magnum with stock bottom end. Cnc ported promaxx heads single plane intake, custome grind cam in excess of 520 lift. The motor should run good but with only 9 to 1 compression I can’t see it making a whole lot more than 400 hp. Unless I put the 10.5 to one pistons in it but at this point I’m not planning g on doing that.

I figure if I get the 46re trans , shift kit or manual valve body, a 3000 stall converter ( 727 converter should work with a non lockup model) and just go through it with a rebuild I think that will be more than enough for my setup.

 

[Bobzilla]

I’d even do the 46re for cost effectiveness. I mean the Dakota guys run these style transmissions and they’re making it work.

My engine will be a 360 magnum with stock bottom end. Cnc ported promaxx heads single plane intake, custome grind cam in excess of 520 lift. The motor should run good but with only 9 to 1 compression I can’t see it making a whole lot more than 400 hp. Unless I put the 10.5 to one pistons in it but at this point I’m not planning g on doing that.

I figure if I get the 46re trans , shift kit or manual valve body, a 3000 stall converter ( 727 converter should work with a non lockup model) and just go through it with a rebuild I think that will be more than enough for my setup.

At that power level you don't need a lot of upgrades in a 518 or 46RH (non lock up) to meet your goals. Then you can run any 727 style torque converter.

If you go with a lock up version, the converter is a very specific part. Cope Racing Trans is getting them from Precision Industries and they require a spacer between the engine and transmission.

 

[Budget mopar guy]

At that power level you don't need a lot of upgrades in a 518 or 46RH (non lock up) to meet your goals. Then you can run any 727 style torque converter.

If you go with a lock up version, the converter is a very specific part. Cope Racing Trans is getting them from Precision Industries and they require a spacer between the engine and transmission.

As far as manual valve bodies go, the early non lockup trans508/46rh, do they accept the 727 valve bodies or are their valve bodies specific to them and I’ll need to source one myself from a company who manufactures them specifically for that transmission

 

[Bobzilla]

As far as manual valve bodies go, the early non lockup trans508/46rh, do they accept the 727 valve bodies or are their valve bodies specific to them and I’ll need to source one myself from a company who manufactures them specifically for that transmission

The valve body is specific to the overdrive transmissions, so it is different than 904/727 valve body.

You do not need a manual valve body at your power level goals. Keeping the factory valve body and adding a Transgo kit will save a bunch of money over a manual valve body. Then you can use that extra money on a converter upgrade.

Start watching some videos on the 46RH/RE transmissions you will get an idea of the parts layout and whether it's in your abilities to do the work yourself. They are not bad if you go slow and pay attention to the details.

 

[Clelan]

I have a fairly stock built A-500 (42rh) in my Duster. It has about 25000kms with various different engines infront of it during that time. It currently runs 12s with a 421 stroker and a 4.30 gear. It has a Trans-go shift kit if I remember, and a 3500 stall non- lock up converter from TCS.
You have to remember that these Transmissions were first put in trucks that weighed alot more than an A body so a fairly stock rebuild will take alot of **** in a light car.

Cley

 

[TT5.9mag]

All of the modifications you do to a 727 or 904 to make em live behind a 450hp small block will be the same for 42/46 re/rh with regards to clutches, bands, etc. As @Bobzilla mentioned the valve bodies are specific to OD lockup units. Cope has them. A mildly built 46 will handle a good bit of power. And if you really get serious the 48 series stuff can be used. And diesel guys beat the crap out of those things.