I have been trying to educate on the 727 Valve body. Seems like most of the internal parts were consistent year to year from the parts manual. 66 pretty much had one valve body part number for all models. 67-68 had a change in part # and you now had 2 basic versions one for HP and one for the others. Seems like the only part different was the transfer body (plate body). 69 the part number changed again and stayed same through 70-71. But some of the parts did change like the plate number. Not sure how that can happen, unless the plate was the same with just a part number change administratively.

Seems like the VB part number 21-139-4 was an assembly part and the only way to get the actual body. All the other individual parts are listed separate.

So was there any real difference, or was it primarily some lever parts that changed from 66 to 71. I realize the plate body has a difference between the HP and normal, but what about the main body itself?

I have one that was probably overheated and had gummed up and stuck the various valves. Not sure what it is from, but the main body has casting # 2892348 and looks like a late Dec 68 casting date. So I assume for a 69 trans. The plate body is the common LP 2801295. I assume the plate is the 2838043 which is common between HP and normal transmissions. Can't find a reference for the casting #2892348, but if that is just the body number, and the part is listed as an assembly with a different number that could be the reason.

Any good source to read on the VB differences in the 66-71 time frame? What are the difference between the 66 versus 67-68, versus 69-71. Primarily interested in the V8 727. From the internal part numbers seems like the important parts are all the same. Unless the upper body had casting differences that effected performance.

There were more changes from year-to-year than I can list. Some notable changes that I have observed:

'66 had an orifice restrictor in the rear servo feed channel, this delayed the manual 1-2 upshift.

'67-'68 the diameter of the throttle and kickdown valves changed. '67 was the introduction of PTK for the /6 and a sense port was added for it. VB casting appearance changed, more rounded corners.

'69-'70 the addition of a plastic shoe on the rooster comb for the new NSS and a pressure relief ball was added; both were late '68.

'71 was a complete redesign with PTK for the V8 and the addition of the 1-2 shift control valve with a new passage to feed the accumulator.

Thanks John, I have come across some of your post in searching.

So is one VB considered better then the other? Primarily trying to understand why the 2466886 transfer plate for the hemi/HP V8, and also I have seen VB upper bodies with cast #2801856 in the 67-68 years, and 2892348 in the late 68-69. Some have the hemi 886 transfer plate, and others the low performance 2801295 plate. So I guess is the pressure relief ball and spring a benefit for the 69 up VB?

The only difference I have seen in transfer plates of the same year is the depth of the channel that feeds the rear servo. In the pic below you can see that the channel on the right is considerably deeper; this allows higher flow for a quicker release which is beneficial during a manual 1-2 upshift but risks servo damage during application.

The pressure relief ball is intended to relieve pressure over 300 psi which can occur when Reverse is selected when the trans is cold.

Dragon Slayer,
I have a NOS plate #2466886 for the 68-9 426,440 transmissions. I'm local here in the Tidewater area if you want to examine/compare against the ones you have. Send a PM.

Jim, I have one I have compared.
John, The Rear servo is only engaged in Manual Low and Reverse. The 1 to 2 upshift manually would release the pressure on the rear servo. So is the deeper channel a quicker relief or a quicker application in a 2 to 1 manual down shift? From what I have seen from the parts manual, all the 66 transmissions used this plate, but starting in 67 it was only used on HP transmissions for the Big Blocks.

I don't know is the larger channel faster flow, or a time delay in reaching necessary pressure to start applying the band.??

For the "why", you'll have to ask the guys who designed the trans...I can only speculate.

The deeper channel feeding the rear servo would make for both a quicker apply and a quicker release. This would seem to be beneficial but the downside is, when the rear band is applied in Reverse, the in rush of higher pressure fluid can cause band/piston breakage. Line pressure in Reverse is increased by a factor of about three and the cold pressure can exceed 300 psi.

In later years they addressed this problem by using a restrictor orifice and later yet a check ball to route the incoming fluid through a smaller orifice and outgoing fluid through a larger orifice.

would the high pressure in reverse be the reason there are billet pistons on the market with stabilizer rings to keep the pistons from cocking in the bore ?

Thanks for the info, I did trace the channel to the input via the plate and there are 2 small square feed holes which would restrict flow. Was not sure if these channels stay full all the time or have to be refilled at apply. Which would be a delay in apply. If they are filled, then less restriction and quicker fill makes sense.

The late 68 and up do have a relief ball and spring to limit pressure to the rear servo when in Reverse.

The transfer plate is completely immersed (below the fluid level) so there's no place to drain to.

Happy New Year to everyone on Moparts.

I think you guys have been reading my mind about Vb Separator Plates...
I have several different ones here from early 60’s to 78.
Some have a large hole above the channel orifice.
Some have a small hole that B&M say drill to 3/16.
Some have ‘No hole’ as per the B&M own plates.
And to top it All, transgo says “fit a 1/4 ball in there”...

I was always happy to follow B&M advice on all things VB, but.
Now I have done a few Transgo VB’s, they are more ‘up to date methinks’?

Best wishes from Limey

Here are some of the interesting items about VB I found going through the Mopar parts manuals for 727s, service manuals and the Master tech lessons.

In 1966 all the VB were the same part number with same internals regardless of transmission model matched to engine. They used the same plate and aluminum transfer plate. The 2466886 deep channel version.
In 1967 through 70 there are 2 basic VB. The version for LP engines and HP engines. The internals are again all the same inside a year. The only difference is the transfer plate. The HP get the deep channel 2466886, and the LP get the new 2801295 with narrow channel. The plate was the same.
67-68 VB did not have the plastic isolator for the neutral safety switch, the body changes number because a few valves changed.
69-70 VB have the isolator and added a pressure relief ball and spring, body changes again, because of the relief valve, but are otherwise the same as the 67-68 internally

So if the vb is original and has the 2466886 bottom plate it came out of an HP transmission 67-70.

71 is a revision and there is an extra valve, extra springs, and many differences depending on model, engine, transmission. Mix match of plates, and transfer plates. So now, there are several VB part numbers and while you can narrow down what you have by the transfer plate number, there are spring and plate differences that prevent you from knowing exactly what you have. The one thing I am not sure, is the later model 71? and up seem to have a stamped number punched through the plate. Is that meant to be an identifier of the plate? If so that might help narrow down what you have.

By the way, in 71 the accumulator operation seems to have changed. It get line pressure in a different way, has this new valve pressure applied on the side, and the spring location or no spring depending on LP, HP 440, or Hemi/6 pack. But that is another subject.

The number punched in the steel separator plate is the last three digits of the plate's part number.

Wasn't there was an issue with trans fluid draining back from the converter that caused slipping when first started? I thought that this was addressed with an update to the valve body. I have a 68 Chrysler that I would like to do this mod. to and also add the part throttle kickdown to. Would I be better off using a later valve body or modding the one I have? Thanks, Mike

The factory never addressed converter drain back but Transgo makes a kit to allow converter refill in Park.

https://www.ebay.com/itm/Transgo-TF6-TF8-Shift-Kit-No-Yo-Yo-SK-TFSC-/293068937363

PTK can be added to your '68 VB, it's basically a bolt on.

i have used several of those trans-go kits with good results.
as an extra, you can now check the fluid level in park.