904 giving up the ghost?

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Alright here are some pics of the "old" broken valve body... i'm thinking I should get a tray to separate all the springs and pistons to keep it all organized, will I be swapping over anything from the valve body itself to the "new" one (springs)? And what about the separator plate and transfer plate? I'll get the new VB apart and post pics soon.

EDIT: That tray looks dirtier than it is it's an old (but CLEAN) cookie sheet with probably 30 years' worth of baked-on residue, that stuff is not coming off lol.

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That 1-2 shift hole is tiny. Drill it out to at least 1/8". I go 3/16" on every one I do, but I think just removing the ball will do the same thing...maybe somebody has experience comparing that difference.
 
That 1-2 shift hole is tiny. Drill it out to at least 1/8". I go 3/16" on every one I do, but I think just removing the ball will do the same thing...maybe somebody has experience comparing that difference.

I know it's tough to describe on here but which hole is that exactly? I'm debating just buying a TransGo TF-2 and going all the way with a full shift kit but if I can make things work better with what I have then that's OK. I liked how the trans shifted before, aside from the part-throttle shifts being way too early like any stock Torqueflite (yes even with the KD linkage adjusted properly).

I searched online and found a set of instructions for a TCI shift kit (can't find any for the TransGo kits) and from what I've read I don't think this valve body has many modifications. The only things I've noticed so far are the lack of a check ball in the transfer plate at the top location (going off my last pic) compared to the stock late-70s VB and there is no pressure relief spring or check ball in the lower-left corner of the upper casting; I'm wondering if that may have contributed to the cracking?

I still have to pull the springs and valves from the upper casting though, I know SOMEthing has to be different with this VB because the car shifted at 5500 RPM at WOT in Drive which a stock 904 doesn't do in my experience. The shifts also felt firmer than stock but only slightly.
 
In the last pic of post #26, it's the tiny hole below the low/left check ball hole; 2 3/8" from the bottom to the center of the hole; and 2 1/2" from the left to the center of the hole. Sharpie it and post pic if you want to double check. I'm too lazy to learn how to post pics.
 
Ok I think I know what you mean, is it the one i'm pointing to in the first pic?

Got the separator plate off and there are NO check balls in the transfer plate at all. Also looks like someone drilled a bypass in the transfer plate? I've seen references to doing that on the valve body casting but not the transfer plate?

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Yes, that's the hole. I think maybe most experienced builders just leave out that ball and don't drill; but I'm pretty sure I don't know.
 
I looked closer at my 1970 FSM and in the picture of the transfer plate that drilled notch is there so it must be from the factory. I think I'll leave the transfer and separator plate alone and just compare them to the newer ones to see if there's a difference and move on to the valves and springs.
 
OK I got the 'new' valve body assembly apart and there are some distinct differences in all 3 parts. The new one is supposedly a late-70s 904 unit but it doesn't have the part-throttle kickdown module which is fine, I got used to manually downshifting anyway. The thing is the separator and transfer plates are not the same between my old 1966 version and this late-70s one so I don't want to just mix and match parts and end up having things not work right (or burn up my transmission). I bought the digital version of the Torqueflite Handbook by Carl Munroe and that was only a little helpful, I still don't understand the differences between the two units and what each of the hydraulic channels do. I really don't want to put the newer VB on the older separator and transfer plates if there's a chance it won't work and I'll have to tear the damn thing apart again.

I'll try to post some pics comparing the components side-by-side but I'm thinking at this point it might be better to just use the entire 'new' valve body assembly and perhaps modify the parts that I can to make it perform a bit better? The most noticeable non-stock feature of my old VB was the raised WOT shift points; what determines that? Is it in the valve body or is that all handled by the governor unit? Like I mentioned before aside from the higher WOT shift points and slightly firmer shifts my old unit didn't act much different than stock.
 
Ok, valve bodies: newer on left, older on right

Separator plates: newer on RIGHT, older on left

Transfer plates: newer on right, older on left

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Sorry if I'm being impatient but this car has been down for too long now I'm getting withdrawal from not driving it lol, really want to get it back together before the end of this weekend. Aside from drilling out that tiny 1-2 shift hole to 3/16" what other mods can I do before putting it all back together?

Also can I just check the valves for free movement in the valve body casting and leave it alone or is it necessary to disassemble the whole thing and clean it out?
 
If they move without sticking then they're good. Some valves can't be checked without further disassembly tho. That is an extremely tiny 1-2 shift hole, so you'll see lots of improvement there.
 
If they move without sticking then they're good. Some valves can't be checked without further disassembly tho. That is an extremely tiny 1-2 shift hole, so you'll see lots of improvement there.

Ok cool I'll do that, I also found instructions for a B&M kit online would it be a good idea to drill the other passages too?
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Also the part about installing a 1/4" check ball inside the spring on top of the 1-2 shift valve, I could use one of the extra 1/4" check balls I now have from the old valve body would that be a good idea? What does that do exactly? In these instructions it says to do that for "off-road racing applications only" but a TCI kit I found says to install the check ball for all applications...?
 
Alright i'll just enlarge those two (A and E). So what does enlarging the B, C and D holes do? And what effect does putting a check ball in the 1-2 shift valve spring have? Just curious, all these shift kit instructions say what to do but they don't say WHY...
 
The TransGo kits are more informative, but they don't specify a ball in the 1-2 shift valve spring. Drill out the hole above and to the right of hole A to 3/16" for a firmer 2-3 shift.
 
Well, a month later and it's finally back together. Drilled the separator plate, cleaned it up and put everything back together. I didn't have a torque wrench that could go down to 35 in-lbs and Harbor Freight is out of stock for some reason so I very carefully snugged up the screws by feel. My transmission works again YES!!! @CudaFactHackJob thanks so much for your help! I noticed a big improvement in the "reaction" time of the shifts compared to my old VB; the shifts themselves don't feel much harder but if I manually shift from 1-2 it's almost instantaneous whereas before it felt like almost a full second delay to initiate the 1-2 shift after I'd move the shift lever.

I didn't adjust the KD cable much yet but I don't have any WOT kickdown, hope I didn't screw something up in there? Feels like I don't have much room for adjustment left in my Lokar KD cable before it starts limiting how far the throttle can open but I haven't really tried.
 
So this valve body was messing with me... it DOES have part-throttle KD even though I didn't see the module for it and I didn't notice it downshifting before because of my loose converter and how quickly it happens. It used to have a slight flare when automatically downshifting from 3rd to 2nd but not anymore it's like the snap of a finger and it's in the next gear now.

This is definitely better than how it ran before, shifts are noticeably crisper and happen instantly when doing it manually. I assumed before the looong delay for manual 1-2 shifts was just the way it worked but apparently not! The part-throttle kickdown works great too, I don't have to manually downshift when turning a corner anymore it does it almost as soon as I get back on the gas or if I give it a little extra to pass someone. Tomorrow I plan to drive it to work so we'll see how that goes at freeway speeds. Needless to say I'm glad I didn't leave it stock this is much better.
 
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