727 Rev Pattern manual shift

[67 440 chrg]

Is it normal for the pump to not operate in park . If I go from park to any gear right after starting it will barely have enough presure to move. If I go to neutral for a second first it will go into gear strong. If it is normal will it burn it up sitting in park idling.

[cudabob496]

I have a 727 with a reverse manual valve body. After I start the car and warm it up for a few minutes, when I put it in reverse, it takes about 10 seconds for the tranny to fully engage.

[dodger1]

I think the pump does not operate in PArk - you need an "anti-drainback" mod to fix that. J.K. the tranny guy should have more on this

[John Kunkel]

The front pump is hooked directly to the crankshaft so, if the engine is running, the pump is pumping. However, if the shifter is in Park the pump pressure isn't directed toward the converter so the converter will be slow to refill after normal drainback. This is a perfectly normal situation regardless of the type of valve body.

Placing the shifter in Neutral for a few seconds will rapidly refill the converter.

[dodger1]

Originally Posted by John Kunkel

.

Placing the shifter in Neutral for a few seconds will rapidly refill the converter.

So the question is - when building a 727/904, is the "anti-drainback" feature worth the $$? (I agree with John that a few seconds in N achieves the same thing, which is exactly what I do with my seldom driven Mirada))

[cudabob496]

Probably not necessary, unless you are at LeMans, and need to run across the track, start your engine, and get going ahead of the other guy. Or if you're at your girl friends house, and her former MMA Champion boyfriend is knocking on the front door!!

[John Kunkel]

There is no "anti-drainback feature", converter drainback is a perfectly normal occurance and can't be stopped. The converter drainback check valve installed in later trucks is a misnomer, it doesn't prevent converter drainback but prevents the fluid in the radiator cooler from draining through the converter.

The one feature that can be added to the valve body to hasten converter refill is the special manual valve offered by Transgo and Sonnax, it allows the converter to refill in Park. A worthwhile mod if the valve body is already removed, I wouldn't pull a valve body just to do that mod but many do.

It's easier to just pull the shifter into Neutral to make the first start of the day.

[67 440 chrg]

Thanks for the replies.

[dodger1]

Originally Posted by John Kunkel

There is no "anti-drainback feature", converter drainback is a perfectly normal occurance and can't be stopped. The converter drainback check valve installed in later trucks is a misnomer, it doesn't prevent converter drainback but prevents the fluid in the radiator cooler from draining through the converter.

The one feature that can be added to the valve body to hasten converter refill is the special manual valve offered by Transgo and Sonnax, it allows the converter to refill in Park. A worthwhile mod if the valve body is already removed, I wouldn't pull a valve body just to do that mod but many do.

It's easier to just pull the shifter into Neutral to make the first start of the day.

Interesting. So the "anti-drainback" mod that's mentioned in several transmission builders' sites is a mis-nomer? Anyway, thanks for the explanation, John.

[BelvedereII]

Hmmmm, I've been wondering about this. I frequently start my car in neutral and let it drift back out of the garage to keep the fumes/noise down. However, when it starts and I hold the rpms up around 1500 the car will surge forward. It frequently then stalls (no choke) and will drift back but when started again will surge forward again. After a couple minutes to warm up it seems reluctant to pull itself backwards into the street, but going into 1st seems to be working right off.

Reverse manual valve body, 9.5" Dynamic converter.

B II

[John Kunkel]

Originally Posted by dodger1

So the "anti-drainback" mod that's mentioned in several transmission builders' sites is a mis-nomer?

Yep, a better term would be "the quick fill" mod as some others call it.

[John Kunkel]

Originally Posted by BelvedereII

However, when it starts and I hold the rpms up around 1500 the car will surge forward. After a couple minutes to warm up it seems reluctant to pull itself backwards into the street, but going into 1st seems to be working right off.

Surging forward in Neutral and a balky Reverse is caused by a rear clutch that's not releasing. If the trasns is new it could just be a tight clutch pack but if it has some miles on it the problem is usually a failed Belleville spring in the rear clutch.

[BelvedereII]

I'd guess a tight clutch pack then, and last night found out the other Mopar guys I race with have experienced the same thing in their manual vb 727's.