C4 REPAIR ASSISTANCE

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OpelGT+3point3
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C4 REPAIR ASSISTANCE

Post #1 by OpelGT+3point3 » Sat Jun 24, 2017 3:17 pm

If anybody has a C4 problem I can probably help. Anybody interested in repairing their C4 I can assist. I'm not really interested in helping with a complete rebuild because that's too overwhelming for the beginner. You have to be able to post pics. I'll need info on the condition and performance before teardown; like slipping, , no reverse, no forward gears, no second gear or no third gear; etc. Before you start, make sure your trans is to the full mark. Overfill it an inch to make sure. IF you think it has to come out for rebuild, then overfill it several inches to double check since it's probably fried anyway. Many C4s have the wrong stick or tube combo. A low fluid level will sometimes engage after warmed up, jump out of gear around corners, or on acceleration.

mustang6
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Re: C4 REPAIR ASSISTANCE

Post #2 by mustang6 » Sun Jun 25, 2017 2:13 am

OpelGT, thanks for being such a great resource to this community. I've seen many instances where you have helped people out. A few years ago the C4 in my 67 Mustang (w/289) started slipping and quickly lost 2nd gear (and I presume 3rd, couldn't get to 3rd when 2nd would freewheel lol). I limped home 20 miles in first gear then subsequently pulled it and replaced with a rebuilt AOD. I always planned one day to open up the C4 and see what happened, I figured the 2-3 band broke because it happened so fast, the fluid never looked or smelled burnt, and adding fluid above the full level didn't help. Maybe I will tear into it and post pictures you can comment on, although I'm guessing it needs a complete rebuild since it was unknown miles when I got it, worked flawlessly for about 10 years/20K miles before it crapped out. Anyway, thanks again for being such a resource to the board.
Scott

68 Mustang 200 ci, 250-2V head, H/W 5200, Dual Headers, Comp Cams 252H, DSII w/ MSD 6AL, T-5, V8 suspension.

65 Ranchero 200 ci, late 170 head, Autolite 1101, 3.03 3 speed, Maverick 8" 4 lug rear with 3.55 gears.

OpelGT+3point3
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Re: C4 REPAIR ASSISTANCE

Post #3 by OpelGT+3point3 » Sun Jun 25, 2017 1:43 pm

If the band breaks or burns off the friction material, you will still have third. A 'complete rebuild' can mean a lot of different things, and often bad hard parts are overlooked and reinstalled; so it fails again. Most of a C4s problems are in and around the two front drums, so it's usually an easy fix.

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wsa111
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Re: C4 REPAIR ASSISTANCE

Post #4 by wsa111 » Thu Jun 29, 2017 8:23 pm

I have a 67 C-4 with a transgo shift kit. Trans was rebuilt & converted to dextron.
At a 1000 rpm idle if I shift it into Drive it engages smoothly. If I shift from P or N into reverse it slams in gear???
Low & reverse servo problem or can I restrict the full line pressure when placing into reverse.
If I place it into D then right into R its ok???
67 mustang,C-4, with mod. 80 hd, custom 500 cfm carb with annular boosters, hooker headers, dual exh.-X pipe, flowmaster mufflers, duraspark II dist. with MSD-6AL. Engine 205" .030" over with offset ground crank & 1.65 roller rockers. 9.5 comp., Isky 262 cam.
2003 Ford Lightning daily driver. Recurving Distributors. billythedistributorman@live.com
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OpelGT+3point3
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Re: C4 REPAIR ASSISTANCE

Post #5 by OpelGT+3point3 » Fri Jun 30, 2017 6:07 pm

wsa111, you might try a new return spring in the reverse servo; or a stronger spring. Or restrict the passageway to the reverse servo. But the problem might be in the direct clutch apply. Is reverse delayed and does it feel like there are two separate applies? The low/reverse band with the reverse/high (direct) clutch accomplishes reverse gear and they need to apply at the same time.. EXCESSIVE direct clutch clearance could cause this. How is your 2-3 shift? Spin-up between 2 and 3 at medium throttle and def at low throttle? 1k idle is very high without a high stall converter. Also, the rear end gears could be worn and could cause reverse engagement harsh but sometimes not D. Many forward clutch packs have a cushion spring and some directs do not.

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wsa111
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Re: C4 REPAIR ASSISTANCE

Post #6 by wsa111 » Fri Jun 30, 2017 7:23 pm

2-3 shift is fine. I guess i need to pull the reverse servo cover & take a look. Hope i don't loose the tang for the band, then i will have to drop the pan & pull the valve body??
67 mustang,C-4, with mod. 80 hd, custom 500 cfm carb with annular boosters, hooker headers, dual exh.-X pipe, flowmaster mufflers, duraspark II dist. with MSD-6AL. Engine 205" .030" over with offset ground crank & 1.65 roller rockers. 9.5 comp., Isky 262 cam.
2003 Ford Lightning daily driver. Recurving Distributors. billythedistributorman@live.com
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OpelGT+3point3
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Re: C4 REPAIR ASSISTANCE

Post #7 by OpelGT+3point3 » Fri Jun 30, 2017 9:23 pm

wsa111, It won't fall. First check that reverse band adjustment; could be way loose. And check the molded seals on that reverse piston. If they're stiff, they won't seal very good. Most rebuilders don't replace that piston but they're only $8. The best 2-3 shift will actually spinup a bit at extremely slow acceleration; slower than you would ever drive it. Most have too much overlap. They feel firm but they're usually just hard because they're in 2 and 3 at the same time. Run the shortest modulator pin as possible.

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