904 for Towing?

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xLURKxDOGx

xLURKxDOGx

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I’ve got a rebuilt 904/360 magnum that’s in my valiant currently. I want to pull that combo out and put it in my 72 360/727 D100. My question is can only assume there was a reason they put 727’s behind small blocks in trucks but can anyone fill me in on potential downsides other than the 904 being shorter.

Thanks,
Jake
 
The 727 is a heavy duty tranny that can handle a lot more torque and abuse. Chrysler put them in trucks and vans for that reason, even in some 6 cylinder engines. 904 transmissions are good in cars and low powered trucks. They build up heat, so an extra trans cooler is recommended. See #3 post. My late 1980's 318 powered pick-up truck came with a 727 non lockup trans. from the factory. --------- I'd swap engines and keep the 727.
 
This is the 21st century. Lots of heavy duty parts are available to upgrade the 904 if you're afraid you might hurt it. I think a good cooler though and you will be fine. Since you already HAVE IT, that's the biggest thing right there.
 
Most all 904 trans missions in Truck's, Taxi's , Vans, and fleet vehicles. Had a Part throttle kick down servo, Easily installed . three screws hold it on the side of the valve body. . This does not allow the transmission to lag in the high gear after slowing up for a turn or traffic and then trying to resume speed without using throttle pressure manual kick down.
Performance cars did not come with them due to safety reasons. The slightest touch of the throttle and it goes down into a second gear as needed. This is a great add on for any transmission 904 or 727. I installed one on every automatic car I owned.

A lot of /6 vehicles had them also. Same servo for 904-727. If any one of you can locate one give it a try. You will never have to pull the transmission into a lower gear. You will always want one on every mopar.

It does it by itself. Give it throttle and it downshifts. as soon as it shifts up give it a little more and it down shifts. You can keep doing that until you are into manual throttle pressure kick down at wide open throttle. Wide open throttle shift can be raised with a lighter governor piston in the tail shaft. Both are very easy to do in the car. Most all north east 340's I have owned had the lighter governor. Performance cars never had the servo due to the fact that they were a little touchy to drive in the wet with a sure grip.

upload_2019-9-20_7-55-17.jpeg


upload_2019-9-20_7-56-21.jpeg


The top right out of the three shown below is 340 and 426 max wedge lighter governor piston They are the same for both motors

upload_2019-9-20_8-4-46.jpeg


Easy to remove and change your kick down passing gear shift point. After removal you can change the piston or you can do it on the tail shaft in the car



These two up grades will totally change your drive-ability on a performance car .

The kick down servo only for towing. I would not do the governor for towing. It will tear the trans up with a higher RPM shift with weight
 
RustyRatRod said:
This is the 21st century. Lots of heavy duty parts are available to upgrade the 904 if you're afraid you might hurt it. I think a good cooler though and you will be fine. Since you already HAVE IT, that's the biggest thing right there.
Click to expand...
Thanks Rob, It’s been built for abuse and has been since behind the 360 magnum.

Jake
 
You can always have the 727 ready for when you need it. They made them for a reason. They did a lot of things just like we did a long time ago that we got away with, but with time comes experience and better decisions. you shouldn't have to modify something to do something that the correct part will already do. Your money.
 
RustyRatRod said:
I think it will be fine. What gear is in the truck, do you know?
Click to expand...
It had 3.55 when I got it but I take it on the freeway. I’ll tell you what, that 4000k hum got to me really quick. I put 3.23 in there now and it’s a good balance.
 
xLURKxDOGx said:
It had 3.55 when I got it but I take it on the freeway. I’ll tell you what, that 4000k hum got to me really quick. I put 3.23 in there now and it’s a good balance.
Click to expand...

The 3.55 was better for towing. What's the rear tire height?
 
Oldmanmopar said:
Most all 904 trans missions in Truck's, Taxi's , Vans, and fleet vehicles. Had a Part throttle kick down servo, Easily installed . three screws hold it on the side of the valve body. . This does not allow the transmission to lag in the high gear after slowing up for a turn or traffic and then trying to resume speed without using throttle pressure manual kick down.
Performance cars did not come with them due to safety reasons. The slightest touch of the throttle and it goes down into a second gear as needed. This is a great add on for any transmission 904 or 727. I installed one on every automatic car I owned.

A lot of /6 vehicles had them also. Same servo for 904-727. If any one of you can locate one give it a try. You will never have to pull the transmission into a lower gear. You will always want one on every mopar.

It does it by itself. Give it throttle and it downshifts. as soon as it shifts up give it a little more and it down shifts. You can keep doing that until you are into manual throttle pressure kick down at wide open throttle. Wide open throttle shift can be raised with a lighter governor piston in the tail shaft. Both are very easy to do in the car. Most all north east 340's I have owned had the lighter governor. Performance cars never had the servo due to the fact that they were a little touchy to drive in the wet with a sure grip.

View attachment 1715396520

View attachment 1715396521

The top right out of the three shown below is 340 and 426 max wedge lighter governor piston They are the same for both motors

View attachment 1715396525

Easy to remove and change your kick down passing gear shift point. After removal you can change the piston or you can do it on the tail shaft in the car



These two up grades will totally change your drive-ability on a performance car .

The kick down servo only for towing. I would not do the governor for towing. It will tear the trans up with a higher RPM shift with weight
Click to expand...


Don't know how I missed this. Great post, Steve.
 
You can make that lighter governor piston out of your stock one. Take 3/32 out of the center The more weight you remove the higher the rpm it shifts when flat out.
The Governor is the ticket for in drive street racing though. I had one that shifted on its own at 7200 You better have a good motor that twists up or it won't shift if you take to much out of a governor.
A factory 340 light weight governor shifts at around 6000. Perfect for a stock 444 lift cam. I put a 68 4spd. 455 lift cam motor, One year only 4spd cam. In a automatic swinger. I made that one shift at 6500. Auto on column leave it in drive and just plant the throttle. That car was a blast. Left arm out the door right hand on the wheel. lean back and enjoy the tire breaking pull.
Factory stall converter in a 340 is 3000. A weak motor will brake stall at 2800. If you got your **** together on a tuned stock 340 motor you can get it to brake stall at 3200 ish. I found the best street gear for a 340 auto was 323's, 355's were a tad to low. 355's are a good gear for a 4spd. car . 323's it is a little harder pulling out . The tires I used on all my cars were L60x15 same as 27560's

Towing converters in a truck are low stall 2200. They don't work for **** once you go beyond an RV cam and even then they sucked' Guys see the sticker they have on them and they think the have a good converter. I toss the in the dumpster

My tow vehicle gas truck I had a stock 727 3000 stock 340 stall converter, A part throttle kick. 465 lift cam with a dyer's 671 blower and two 7500's. That truck would pull a house. The trans was fresh and yes it did have throttle pressure . Look close at the pictures you'll see it. That was an every day tow vehicle. You would not believe the heads it turned when people would see and hear it pull in with a trailer hooked to it.

. We turned that truck into a 2003 common rail. We were always were looking for more power . That trans is still sitting in the trailer. Heat is what ruins a trans . A good trans cooler is what you need in 71 the 904's in the taxi Coronet's had it all they were a drop in performance 904. That blower off my truck I believe is on someones yellow duster on this site

So what I am telling you if that 727 took what I put it through for a couple years you won't have a problem with a stock 904 with the mods I mentioned. My truck had 37 inch tires 410 dana 60's. We Painted it two tone silver when we put the common rail in it. That was the color of the diesel cab we needed for emission exempt.

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I'm pretty sure a 904, "properly used" will handle anything a Val sized car can legally and safely tow. Crackedback? You 'member the flaming broad was gonna tow some darn thing with her 66 Barracuda??
 
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