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I'm trying to help my young nephew again with his '66 289 Ranchero. This time it's a problem with his C4 transmission, and being a 4-speed man, it's not something I'm all that familiar with. Here's the story.

When he got the Ranchero, the transmission had no high gear in it. On inspection, there was no lining left on the high/reverse drum clutches, and the direct drum ones weren't great either. It needed a complete rebuild. The tag on the transmission said 'PEE 289 6M8 B2'. That date code '6M8' (Dec. 8th, 1966) suggested it was more likely a '67 transmission, but several of the parts inside had earlier C4, C5 & C6 casting numbers, though the valve body said C7AP on it.

A friend of his, who had rebuilt a few GM transmissions, did the C4 for him. He thoroughly cleaned everything out, but only 'flushed' the torque converter a few times in a solvent tank. He gathered advice from several Mustang and other SBF forums, from a couple racers, from the shop manual and other books, and from YouTube. He got a good rebuild kit from Oregon Performance Transmission, which included Alto clutches and plates, Kevlar bands, the Alto reverse/high 'Power Pack' six clutch disc kit, and a TransGo 47-2 shift kit.

When it came to installing that Transgo kit, they found a couple odd things in the valve body. The first was that the boost valve and bushing had been installed backwards, at least according to the TransGo instruction sheets. Similarly, there was a flat-sided disc or 'puck' there that wasn't in their instructions, and a spring that should have been there had been replaced with a check ball. Lastly, TransGo had provided a .110" drill bit and wanted a specific hole in the valve body separator plate drilled out. What they found was that the hole had already been drilled out...but more like .250"!

When the rebuilt 289 engine was fired to break-in the cam/lifters, after the obligatory 20+ minutes at 2,000-2,500 RPM, they dropped the engine to idle and topped-off the transmission fluid...ATI 'Super F' (synthetic). The rear axle had been lifted on jack stands, so that the tires cleared the ground. The trans was moved into Reverse, and the tires rotated backwards as they should. Then they put the transmission in low gear, and again the rear tires were rotating forward as they should. The revs were brought up to about 2,000, and the trans was shifted into 2nd gear, and the shift went quickly and smoothly. After about 30 seconds, it was shifted into high gear, and again it shifted quickly and smoothly. This was repeated a few times over the next couple of days, as they dealt with some issues about timing and idle mixture/speed.

At some later point, the engine was run again in gear, and the RPM's were brought up. As the speedometer indicated they were aproaching 50 MPH in High gear, the transmission seemed to literally 'fall out of gear'. The speed fell off, but the engine RPM remained the same. Only by letting the engine speed drop down could they get the transmission to re-engage. But again as speed got up to about 50 MPH (less than 3,000 RPM in High), the transmission disengaged again, and it has continued to do that ever since.

Asking some friends got them the suggestion that they install a pressure gauge, to see what was going on in the transmission. Fluid levels were again checked. The dipstick in fact indicated that it was slightly over-full (idling in Park), though they had installed an aftermarket chrome dipstick & tube, so didn't know how reliable the readings were. On running the engine, they saw 95-100 PSI at idle in Park. Shifting into Low they got the same reading, from idle up to 2,500 rpm or so. And again, in both 2nd and High, the indicated pressure was right around 100 PSI. In Reverse, pressure went up to about 165 PSI. Of course, with the tires in the air this was with virtually no load on the engine, so the vacuum level did not drop appreciably due to throttle opening.

At the moment, I'm leaning towards suspecting the valve body, given that the pump seems to be putting out at a good level. It's been suggested that we check that the modulator spool valve wasn't put in backwards when it was replaced, which will be done as soon as he's home again. But beyond those ideas, I have no clue. As I said, I'm no expert.

Any other thoughts about what could be going on? We'd really appreciate any insight here.
 

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Look at these PDF's and determine exactly which valve body you have...
Proceed from there with the proper shift kit.

Also... think about "where did the clutch lining materiel from the high/reverse clutches go when it peeled off?"
Probably into the converter and the cooler.... and the fresh fluid flushed it out and back into the trans...

Now you will fight sticky valves and governor 'till the cows come home. Likely the cause of the shifting issues.

If you are lucky... (I'm not) you can pull the valve body and governor and clean them and try again....

....but the only real way to prevent sticky valves/gov is to strip it all down and wash everything again.
AND get the converter cut open and cleaned properly... and don't forget to FLUSH THE COOLER!

Automatic transmissions demand attention to detail and above all else, CLEANLINESS!

The tiniest bit of debris can ruin your day.

64-66 C4 VB.jpg


164597
 

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Discussion Starter #3
Look at these PDF's and determine exactly which valve body you have...
Proceed from there with the proper shift kit.

* Thanks for posting those exploded diagrams, they'll be very helpful.
As for the valve body, it's definitely the C7 version. And a TransGo 47-2 kit was installed in it when the trans was rebuilt. As mentioned, they found that the spring and inside valve of the accumulator were missing, and in their place was a flat metal puck. Where the cutback valve was, a steel check ball had been inserted into the valve body cavity ahead of it. I don't know what effect either of these changes might have??


....but the only real way to prevent sticky valves/gov is to strip it all down and wash everything again.
AND get the converter cut open and cleaned properly... and don't forget to FLUSH THE COOLER!

* I also thank-you for your cautions about cleanliness, and the effects of not doing that. He's assured me that everything from the transmission was washed thoroughly several times with clean solvent, and some parts were steam cleaned. While they did not have the converter cut open, it was flushed several times with a pressure stream from the parts cleaner, while the converter was rotated as it stood on its side. The cooler (external Hayden) was also flushed, in both directions, with solvent, and was then blown out with 115 psi air. None of which means that there couldn't have been some debris left inside either.
 

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Sounds a bit like might been another brand shift kit installed already. Some others like B&M + TCI etc use plugs to block valve movement

a 1/4 ball in the cutback is common.

It would be hard to tell with no load as it is in the air . I'd be dropping it on the ground and see what is happening. Pressures look ok but as suggested the old torque converter may have polluted the valvebody
 

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+1 on the 1/4" check ball in the cutback.
It's a common trick, the effect is to firm up the shifts.

The way it works... the cutback valve does exactly what it's name says...
It "cuts back" mainline pressure when the car is up to speed and cruising at steady throttle when high line pressure is NOT needed.
This helps efficiency and reduces the load on the pump.
However, it does have some effect (cutback) even before reaching cruise at light throttle, so that the shifts are "comfortable", ie; not harsh or too firm.

Blocking the cutback valve with a ball stops the mainline pressure cutback, and tends to firm the shifts, even at part throttle.
The TransGo spring does the same thing.
If you check, the cutback valve is prevented from moving because that TransGo spring coil binds and doesn't let the valve stroke.
Same effect as the check ball.

From factory there is NO ball OR spring, the cutback valve "free floats" but is pushed one way or the other by gov pressure or TV pressure.

As far as flushing the converter.... Have you ever seen the inside of a torque converter?
Many many places in there for debris to get trapped and VERY difficult to get it all out with a solvent flush.

However... that fresh trans fluid is a very effective flush agent, esp when hot.
It WILL flush out any debris left behind that the solvent didn't get, and dump it straight back into the trans.

I have NEVER been sorry for going to the trouble and expense of either a new converter, OR a "cut and clean" on the old one.

I HAVE been sorry I ever used an old converter...even after "flushing" it.

YMMV

Also, Greg is right, hard to tell whats going on with the wheels in the air.
You need to get it on the ground and drive it. ie; put a load on it.

Edit;
A magnet in the pan helps to collect debris and prevent sticky valves.
Also you "might" get lucky if you try an additive meant for freeing up sticky valves.
Do NOT use the "transmission mechanic in a can" junk!!!!

The only additive I would recommend is the LubeGard red bottle.

This stuff...

Automatic Transmission Fluid Protectant - Lubegard

.
 

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Discussion Starter #6
+1 on the 1/4" check ball in the cutback.
It's a common trick, the effect is to firm up the shifts.

The way it works... the cutback valve does exactly what it's name says...
It "cuts back" mainline pressure when the car is up to speed and cruising at steady throttle when high line pressure is NOT needed.
This helps efficiency and reduces the load on the pump.
However, it does have some effect (cutback) even before reaching cruise at light throttle, so that the shifts are "comfortable", ie; not harsh or too firm.

Blocking the cutback valve with a ball stops the mainline pressure cutback, and tends to firm the shifts, even at part throttle.
The TransGo spring does the same thing.
If you check, the cutback valve is prevented from moving because that TransGo spring coil binds and doesn't let the valve stroke.
Same effect as the check ball.

From factory there is NO ball OR spring, the cutback valve "free floats" but is pushed one way or the other by gov pressure or TV pressure.

As far as flushing the converter.... Have you ever seen the inside of a torque converter?
Many many places in there for debris to get trapped and VERY difficult to get it all out with a solvent flush.

However... that fresh trans fluid is a very effective flush agent, esp when hot.
It WILL flush out any debris left behind that the solvent didn't get, and dump it straight back into the trans.

I have NEVER been sorry for going to the trouble and expense of either a new converter, OR a "cut and clean" on the old one.

I HAVE been sorry I ever used an old converter...even after "flushing" it.

YMMV

Also, Greg is right, hard to tell whats going on with the wheels in the air.
You need to get it on the ground and drive it. ie; put a load on it.

Edit;
A magnet in the pan helps to collect debris and prevent sticky valves.
Also you "might" get lucky if you try an additive meant for freeing up sticky valves.
Do NOT use the "transmission mechanic in a can" junk!!!!

The only additive I would recommend is the LubeGard red bottle.

This stuff...

Automatic Transmission Fluid Protectant - Lubegard

.
Thanks for another well thought-out and informative answer, Galaxiex. We're learning things here!

And it looks like you are absolutely correct about re-contaminating new fluid from what must have been hidden in the converter. We pulled the valve body out last night, and found the same kind of 'black' debris in the fluid, the bottom of the pan, and on the valve body separator plate. Nowhere near as much as when the trans was rebuilt, but obviously far more than I'd like to see there. So everything will have to come out and get cleaned again, with the 10" TCI converter being cut open for a thorough inspection this time.

To get back to our valve body issues for a moment, maybe you could help with this. It is a C7AP-B unit, with a '2P 3' tag. As Gregaust said in his post, it looks like someone had made some changes inside it already, before the TransGo 47-2 kit was installed. I found a number on the separator plate that comes back to a B&M Trans Pak part. One of the things that concerns me, is that a hole that TransGo wanted drilled out to .110", had already been drilled out to 3/16" (.1875"). As best I can figure out, this hole has something to do with the 2-3 shift valve, based on where it connects to in that half of the valve body. Does this sound right, and how would the 'oversize' hole affect it's operation?
Contaminated C4 valve body showing oversize hole previously drilled.jpg TransGo recommended size for separator plate hole.jpg Separator plate hole leads to 2-3 shift valve.jpg
 

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Yep, that gold colored plate is a B&M, but you already knew that. ;)

For the record....
I don't like B&M "shift kits". Their other products (shifters and such) are ok, but their valve body kits suck.
Just my opinion.
Backed by 45 years experience in the trans biz, and having seen, worked on and driven, many transmission types with B&M kits.

Going by old guy memory (not always reliable) that hole is the high clutch feed restriction orifice, and B&M has a propensity to really make those overly large.
Their "claim to fame" is HARD shifts, and those oversize holes are what gives you hard shifts... for awhile....
They also cause friction "distress" and burning of the lining from applying the clutches too violently, witness your original discovery of badly burnt high clutches.

This is one reason I dislike B&M valve body kits, the trans usually only last a year (if that) from those hard shifts.
Seen it time and again, and again, and again.... etc...

All that said... if it were mine I would try to find an un-modified plate and drill that hole to the size called for in the Transgo kit.
It "might" be possible to somehow resize that hole and get it closer to the Transgo size.
There are tricks for doing that.

One trick is to put the plate on a hard flat surface (thick steel plate or anvil) and take a 1/2 inch diameter, maybe even bigger, steel ball (possibly from and old ball bearing of some kind)
Place the ball on the oversize hole with the plate on the anvil, and smack the ball sharply with a small hammer.
This will "peen" the hole smaller and will need to be repeated several times, flipping the plate over each time.
Back and forth, smack, flip, smack, flip, etc...
If the hole is just too big it may not peen down to the size you need.
It will make it smaller, but there is only so much you can peen it before running out of materiel.

Another trick, get a small slug of soft metal, like a little puck made from aluminum, as close as possible to the same diameter size of the existing hole.
Puck should be slightly thicker than the plate.
Put slug in hole, plate on anvil, space the plate off the anvil with very thin cardboard or a few sheets of paper.
Do not put the paper shim under the slug.
The idea is to have a tiny bit of slug sticking above and below the plate.
Smack the slug enough times to expand it tightly in the hole, file smooth both sides and CAREFULLY re-drill the slug in exact center to proper size.
It helps to chamfer the edges of the existing hole first, with a countersink or large drill bit.
And to possibly make the hole even bigger first, depending on the size of slug you find.
A bit of a risky fix as the slug could come loose sometime down the road.

In general, it's NOT a good thing to install a shift kit (any brand) "over top of" an existing different brand of shift kit.

Best solution.... start over with a virgin valve body that no-one has messed with.
Any 67-69 valve body will work.
 

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Yep, that gold colored plate is a B&M, but you already knew that. ;)

For the record....
I don't like B&M "shift kits". Their other products (shifters and such) are ok, but their valve body kits suck.
Just my opinion.
Backed by 45 years experience in the trans biz, and having seen, worked on and driven, many transmission types with B&M kits.

Going by old guy memory (not always reliable) that hole is the high clutch feed restriction orifice, and B&M has a propensity to really make those overly large.
Their "claim to fame" is HARD shifts, and those oversize holes are what gives you hard shifts... for awhile....
They also cause friction "distress" and burning of the lining from applying the clutches too violently, witness your original discovery of badly burnt high clutches.

This is one reason I dislike B&M valve body kits, the trans usually only last a year (if that) from those hard shifts.
Seen it time and again, and again, and again.... etc...

All that said... if it were mine I would try to find an un-modified plate and drill that hole to the size called for in the Transgo kit.
It "might" be possible to somehow resize that hole and get it closer to the Transgo size.
There are tricks for doing that.

In general, it's NOT a good thing to install a shift kit (any brand) "over top of" an existing different brand of shift kit.

Best solution.... start over with a virgin valve body that no-one has messed with.
Any 67-69 valve body will work.
Well, that pretty much seals it! Again I thank you very much for your insights and advice, we really appreciate them.
It's obvious that what happened is exactly what you said to avoid...installing one brand of kit on top of another. And your advice to go back to square one with a stock Ford valve body makes the most sense, especially as my nephew says he is not able or anxious to shell-out big bucks for a name brand one. A quick check around here hasn't turned up any '67-'69 valve bodies yet, but they must be out there somewhere.
 

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You'd be best to start with another stock valvebody or else reverse every part of that original shift kit . If you were to reuse that plate and resize the hole you'd need to compare it to a stock plate .
From memory the shift command that gives manual 1st and 2nd shifts is achieved differently between that kit you have and Transgo.
That hole size is way too big, in reality anything over .125" achieves little to nothing in the way of oil control. I did try many years ago and as already mentioned the shifts were just crazy hard
 
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