Ford C4 Advice Needed

Pony Pilot · 11-04-2014, 09:23 PM

I recently replaced my 383 Cleveland stroker in my SST Mustang with a 438 stroker. HP increase is in the 100 hp region. I re-used the C4 behind the 383 with the 438. The shifts were solid when it was behind the 383, but now with the 438 I had to increase the shift points 500 RPM and have a 600 to 800 RPM spike before the 2-3 shift. Usually, I would conclude that I had excess clearance in the clutch pack, which was true when I removed it and checked with feeler gauges. But, when I put in a fresh rebuilt unit with 6 discs vice the five in the previous trans, I still had the same RPM flare-up. I have built my own trans for years, and .010 per disc clearance has always served me well. I called two well-known trans aftermarket companies with one telling me this is a valve body issue and the other saying it's still excess clutch pack clearance. Has anyone else out there encountered this? If so, what's the fix? Thanks in advance for any help.

Just for background, these trans have 6-pinion planetaries, Alto red clutches, Kolene steels, Kevlar bands, PA Pro-Shift servos, and hardened input shafts.

Karl Owens · 11-04-2014, 10:11 PM

sounds like a band adjustment or intermediate servo issue, the volume of fluid required to release the band causes the delay on the 2-3 shift

C and W Racing · 11-05-2014, 03:31 PM

You also need to verify that you do not have too much end play, also no groved in any drums where the sealing rings ride.
Chuck

1968 SS · 11-05-2014, 05:46 PM

I would say do not waste any more time and money on a C4,and up grade to a Power Glide!!

11-04-2014, 09:23 PM	#1
Pony Pilot Junior Member Join Date: Aug 2012 Posts: 25 Likes: 0 Liked 0 Times in 0 Posts	Ford C4 Advice Needed I recently replaced my 383 Cleveland stroker in my SST Mustang with a 438 stroker. HP increase is in the 100 hp region. I re-used the C4 behind the 383 with the 438. The shifts were solid when it was behind the 383, but now with the 438 I had to increase the shift points 500 RPM and have a 600 to 800 RPM spike before the 2-3 shift. Usually, I would conclude that I had excess clearance in the clutch pack, which was true when I removed it and checked with feeler gauges. But, when I put in a fresh rebuilt unit with 6 discs vice the five in the previous trans, I still had the same RPM flare-up. I have built my own trans for years, and .010 per disc clearance has always served me well. I called two well-known trans aftermarket companies with one telling me this is a valve body issue and the other saying it's still excess clutch pack clearance. Has anyone else out there encountered this? If so, what's the fix? Thanks in advance for any help. Just for background, these trans have 6-pinion planetaries, Alto red clutches, Kolene steels, Kevlar bands, PA Pro-Shift servos, and hardened input shafts.

11-04-2014, 10:11 PM	#2
Karl Owens Junior Member Join Date: Dec 2009 Posts: 68 Likes: 0 Liked 0 Times in 0 Posts	Re: Ford C4 Advice Needed sounds like a band adjustment or intermediate servo issue, the volume of fluid required to release the band causes the delay on the 2-3 shift __________________ NHRA Stock/Super Stock 1078

11-05-2014, 03:31 PM	#3
C and W Racing Senior Member Join Date: Jul 2007 Posts: 554 Likes: 5 Liked 10 Times in 1 Post	Re: Ford C4 Advice Needed You also need to verify that you do not have too much end play, also no groved in any drums where the sealing rings ride. Chuck

11-05-2014, 05:46 PM	#4
1968 SS Junior Member Join Date: Feb 2008 Location: Toronto,Ontario Surprise AZ Posts: 16 Likes: 0 Liked 1 Time in 1 Post	Re: Ford C4 Advice Needed I would say do not waste any more time and money on a C4,and up grade to a Power Glide!!