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Discussion Starter #1
Since the engine is out, I'm gonna tear apart my C4 tomorrow. I've had a 2-3 flare up that I need to fix. I have an H-servo coming in the mail and thought I'd inspect the intermediate band while it's accessable.

Here's a distilled rundown of what I've learned:

The 2-3 flare can be from one or all in combination of a loose intermediate band adjustment, loose direct drum clutch pack clearances, a servo with a large accumilator area, low pressure, and a slow reacting valve in the VB. A "R" servo with the smallest accumilating(release) area, 1 full turn out from snug on the band adjustment, and .006-.010" clearance per clutch in the direct drum will basically eliminate the flare-up. Higher pressure also helps greatly. If the clutches are glazed at all, that will cause slippage when the clutches are trying to apply too.


whats a easy way to up the preasure?


The easiest way to increase the pressure is to install a manual valve body other wise you can increase the relief valve spring tension and that should help too. Remember of course if it was leaking before at lower pressures it will begin to leak even more with added pressure.

Servo choices
There are a few different opinions on the subject, although there is a bit of convergence on the issue around stock R and H servos. GA – I like the R servos. MVW - I like the R servos but have used H's with good success. I spoke to Epping and they use stock servos with the letter machined off. They said the servo makes no difference in their trannies. GH – I use the H model servo because it gives very solid shifts. It is the largest factory unit, highly desirable and plentiful. Make sure you use a stout spring inside the servo (I use a std 351 cleveland valve spring). W8 - I use an H servo with the outer seal removed and 3 flats ground on the surface and I plug the hole in the case. 89C - I never modified any servos, never needed to. An "H" or "R" servo with a Kevlar rigid or flex band has always been more than enough for the 9 second big blocks and small blocks my trannies have been behind. The weakness isn't in the apply area. It's in the release area and until very recently where somebody here posted the apply and release areas of different letter servos, I saw why the "H" allowed a small flareup from 2-3 shift and the "R" didn't. The "R" has a smaller release area that fills quicker thus allowing fluid to pass to the direct clutches quicker to prevent the flareup. "R" servo has a smaller apply area but that is insignificant seeing that properly setup the 1-2 shift and 1st/2nd gears don't have problems. It's the 3rd gear shift that causes the wear on the direct clutches and making 3rd shift harder and quicker is what makes the C-4 live.
Source: http://www.fordmuscle.com/phpBB/viewtopic.php?topic=9911&forum=13&26

So, getting to the intermediate band requires some dissasembly. What gaskets do I need? Should I just get an overhaul kit, or is it cheaper to buy the gaskets individually?

Anything else I shoudl replace? And no, I don't have the spare cash for a trans brake. . .

I do have an ATSG tech manual for the C4 that tells me how to do various pressure checks once the valve is off.

Any info or tips will be appreciated.

Thanks,
Robert
 

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Depending on the age of the tranny since rebuild , Id rebuild it . Get a clutch kit with seals , but be sure you get a kit that has the metal seperator plates for the clutches , not just the clutches themselves . Many cheap kits make you reuse the plates , which can be compared to reusing your pressure plate on a manual tranny .
The job's hardest part is getting the pistons out of the clutch drums . There is a set of springs and or one diaphram spring that have to be compressed so the snap ring can be removed . It can be done with a couple C clamps if your skilled but be careful you can damage stuff or hurt yourself . You might be best to take the drums to a local tranny shop and pay them a few bucks to do it for you or buy the correct tool for compressing them . The tool is not cheap .
Get a good manual that shows the tranny exploded view . Also , when you remove parts do it on a table so you can lay the guts out in order . The tricky part of putting it back together is making sure you have the thrust washer in and in the correct place . You also have to make sure the clutch packs are all fully engaged on the splines of the drum/gear that splines to them .
A C4 is about as simple as you can get , the most complicated piece is the valve body . If you must open the VB , do so once the tranny is done so the parts don't get mixed , etc. Or do it at a different clean location .
 

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Discussion Starter #3
40k or so miles since last rebuild. Replace the clutches, huh? What's that gonna cost me?

Thanks,
Robert
 
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