Auto trans expert opinion needed

[turbobitt]

Ok, Im building an automatic trans to replace the full manual that I currently have. My question is if there is a preferable year valve body to use and why ? I seem to have a selection at my disposal.
valve body #1 - Date coded 1970
valve Body #2 - Date coded 1974
valve body #3 - Date coded 1978

I am familial with some of the differences like the accumulator circuit change somewhere after 1970. Also know that the later VB's had the part throttle kick down module. Would that be a feature to have or does it get disabled in a shift kit anyway? I read somewhere that the 1978 VB has a pressure control circuit for reverse, not sure if this is a beneficial feature.
This will be going behind by Hemi so I am looking for something more performance oriented. I plan on blocking the accumulator so that should even the playing field somewhat. Most of my builds to date have been mostly manual VB's or transbrake applications so I never really educated myself on the full "automatic" stuff.

Thanks,
Allan G.

[John_Kunkel]

Be aware that the casting dates on the VB castings can be a year earlier than the actual application. The punched out 3-digit number in the steel separator plate is a better indicator of the actual model year.

You didn't specify which year case you'll be using. Installing the '70 VB in a '71 or later case will partially block the accumulator. The PTK is a desireable feature but the choices of '74 and '78 aren't that desireable IMHO, the '74 has a modified cooler flow circuit intended to be used with a matching front pump, I wouldn't use a '78 VB for a performance unit (just a personal preference).

Most quality reprogramming kits do have a mod to alter the PTK speeds but the mod is optional.

[turbobitt]

Thanks for your reply,
The case is going to be a 1970 model year out of a Challenger and coincendently going into a challenger. Is it worth while to by a one of those new billet PTK modules and use the matching VB ? The front pump, drum, and rear clutch will be the later type with the wider bushing.
Please elabroate on the differences on the cooler flow circuit, you have peaked my interest.
I know one of the VB's is a 1970 model year for shure and original to the case that I have. I was able to positivly identify the other as a 1978 model year by the seperator plate number. The other could be a 73 or 74.
Allan G.

[John_Kunkel]

Starting in '74 they removed the valve body partition that separated the converter return fluid from the lube fluid, and the front clutch lube was relocated to the output shaft instead of the reactionshaft support as it had been in the past. This, in itself, doesn't prevent the use of that VB in an earlier case but the size of some of the ports in the case was also increased to accomodate the revised rear servo and rear clutch circuits that cantain a check ball. If the case size isn't increased or the check balls removed, there will be a restriction in fluid flow.

The PTK module from one of the later VB's can be installed on the '70 VB but the limit valve won't function...it's cheaper than the billet product and will function the same.

[turbobitt]

John,

What are your thoughts on adding the lub hole in the later reation shaft support ? I ask this only because in the past I have found bushing material in my oil an can only conclude that it was from the front clutch bushing. I am therorizing that since I have been running scarf cut teflon rings(almost zero leakage) and a rollerized rear support(with ol seals) that the bearing is running dry. I have been chasing this problem for some time and found this on two of my full rollerized units. I won't be rollerizing my full automatic anyway. 
Thanks for your insight.

[John_Kunkel]

If the '78 and later is the one you plan to add the lube hole, the 3rd input sealing ring pretty much limits the space to do it, '77 and earlier should already have a bushing lube hole. In the later years the factory intended for that lube to come from the output shaft but it doesn't seem to work like they planned.

I've always thought that some of the '74 mods were ill-conceived, for example the pre-'74 input shaft had its own dedicated lube hole for the input shaft bushing in the reaction shaft support but the '74 redesign depends on the output shaft to do this...I've seldom seen this bushing distressed on the pre-'74 but lots of distress on the later. Same for the front clutch lube hole that was eliminated in '74, I always add one in the same spot as the early.

[turbobitt]

John,

If I wanted to take advantage of the best parts that I have, I'm assuming that I should..
1 - use the original 1970 VB that matches the case to be used. This would include the typical mods such as the TF-2 kit and blocked accumulator and PTK module.
2 - Early front servo and 4.2 kickdown lever
3 - Late front pump with wide front clutch bushing modified for the .060" oil lube hole in reaction support.
4 - Early input shaft with later piston and belville spring to take advantage of the oil lube on the input shaft ?

After looking at the differences in the lube circuite between the early and late, Im not that excited about the changes myself.
Thanks for your insight.
Allan G.

[John_Kunkel]

I see no problems with your plan.