[joes455]

So im performing the duel chamber mod remove the lip seal at dirct clutch and the second seal at the intermediate and blocking revs feed.Some mods involve blocking the 2-3 with a set screw.My ? Is is the hole their blocking is it a feed or discharge or does it perform both functions?How do it operate the band when blocked?

[Half-Inch Stud]

Focus on the 2-3 mod: remove mid-seal in Dir pack, 2nd ring on Center-Support and block the Rev bleed at the sep-plate or more assuradly at the center support hole (1/4" plug).

2-3 accum: ONLY flip the VB piston and remove its spring. Case 2-3 puck-spring-pin remains stock. No pluggings. Some VB pucks need their 3-cast tabs ground flush to make like the 65-70 piston.

[Cliff R]

The accumulator is their to "cushion" the 2-3 upshift. On a TH400 you need to be conservative with the separator plate hole size when making that modification. Most builders also leave out any "waved" steels in the direct drum as well. I've never seen a negative from blocking it but it will shorten up the shift and it will feel firmer with no other modifications. The Transgo kit (1 & 2) provides the necessary parts to double feed without leaving out any parts. You also get improved direct clutch release springs and a much stronger snap ring for the case to retain the intermediate clutch pack. They also supply a modified shift valve and plug to block the vent hole in the VB for full manual control.

Nothing at all wrong with doing a "home brew" shift kit to save some money but you will not get the upgraded parts. You'll also see several "recipes" for doing you own shift improvements, so be careful not to mix-match information as it is well covered on many Forum's and not all exactly the same.........

.https://www.summitracing.com/parts/t...SABEgIsF_D_BwE

[joes455]

Thanks sounds good should I go ahead and would you recommend me removing the center seal for the forward drum set?

[Cliff R]

If you use the Transgo 1-2 kit just follow the instructions.

I'm a big fan of using their kits in the TH400 even though with a little extra work you can easily set one up to double feed direct and get full manual control, plus shorter/firmer shifts, etc. The cost is moderate and you get some nice extra HD components with it.

It's just a personal thing but I've never really been a big fan of tossing out most of the check balls, leaving off a sealing ring on the center support, omitting the direct drum center seal, blocking a feed hole in the case, modifying or flopping accumulator pistons over, leaving out accumulator springs, or drilling stock separator plates........unless you have DIRECT experience with the model you are building so you can achieve accurate and acceptable end results.

Don't get me wrong, I've bought the HD snap ring for the TH400 case to retain the intermediate clutch pack, ground "flats" on the 1-2 shift valve, blocked the exhaust hole in the VB, then all the other mods to double feed direct with good results. In the big scheme of things is just a LOT easier to buy their kit and pretty much do a standard rebuild with good parts, then about the only mod is picking separator plate holes sizing for the shift firmness desired. About the only other thing I'll do is restrict converter feed and block the oil to the 2-3 accumulator.

One has to keep in mind with any transmission is that a big part of shift performance, especially at light engine load will be greatly impacted by how efficient your torque converter is at lower RPM's. You really need to pay attention to some items if you are using a stock or really tight full size converter or your wife may be wearing most of her morning cup of coffee when you place the trans in reverse as you head out to a car cruise on Saturday morning!

On a more serious note huge separator plate hole sizing and other mods done to achieve "window shattering" shifts, especially 1-2 are extremely hard on the internals, especially the intermediate sprag. I actually knew a very accomplished "builder" years ago that never upgraded to a smooth direct drum and 34 element sprag set-up. Instead he would retain the roller type "notched" drum/sprag, stock waved frictions, wave steel plate, and conservative with separator plate hole sizes. Claimed he never had an issue with any of them at any power level. I never tried that deal but did wonder how well it would work as it's impossible to "roll" the roller type clutch over like the "dog-bone" variety............

[joes455]

Thanks Cliff been great help after performing a dual feed mod the reverse blocked off can I still (may sound funny )use the transgo plate? I like the very small 2-3 accumulator feed .060 hole it has,I may not have to install plug with set screw .Your thoughts please sir.

[Cliff R]

The Transgo kit is well thought out and doesn't need any help. For most applications no need to do a 2-3 accumulator mod. I would be conservative with separator plate holes sizing, and make sure to use the VB gaskets they send with the kit........

[Tom Hand]

Like Cliff said, the Transgo kit is worth the money. I have the GM Hydramatic guys' tips on making the 400 shift firmer and quicker and if you go too "strong" with it, and you have powerful engine in a big car with a tight converter, you can do some damage. You might rip the input shaft out of the hub/drum/clutch retainer or you might break other parts. You can make them shift violent with too large of hole sizes and without a converter that "cushions" the power to the input shaft, it can be tough on the transmission.

[joes455]

Thanks everybody, okay well looks like I'm putting the transgo separator plate back in and my big question is I've already used both supplied gaskets . Who sells these gaskets for that transgo 1-2 shif kit?I've forgot that the TransGo gaskets are specific and I've been using the original GM designed gaskets, so that's the reason why my third gear was not engaging properly I believe it's just the case gasket that needs to be modified.

[Cliff R]

The Transgo kit used to come with two sets of VB gaskets. I've never tried to modify stock gaskets but they would have to be an exact match at every hole or you'll get a soft 2-3 upshift......

[joes455]

Thanks Cliff I'm not looking to modify the gasket,are these gaskets only available through TransGo?