Swapping out trans
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From: Wingo, Ky
Swapping out trans
The c4 in my 73 F100 302 is slipping fairly bad but I have a 74 F100 302 parts truck with a great shifting FMX in it.
I have done some measuring and both trannys seem to be the same length. Will the FMX bolt directly in place of the C4? Any help is welcome, thanks.
I have done some measuring and both trannys seem to be the same length. Will the FMX bolt directly in place of the C4? Any help is welcome, thanks.
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From: Wingo, Ky
Anybody have any advice? I don't really want to pull either transmission until I know if its gonna work.
Im not sure if my driveshaft will work if I replace the c4 with the FMX.
The FMX is in a longwheel base truck, the C4 is in a shortwheel base so I cant change driveshats out.
Im not sure if my driveshaft will work if I replace the c4 with the FMX.
The FMX is in a longwheel base truck, the C4 is in a shortwheel base so I cant change driveshats out.
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OK, not a trans man and don't play one on TV, but reviewing your info:
--both from a 302, so it will bolt up.
--if you need to transfer the flex plate so it matches the new trans, your engines are both the same balance type, so no issue there. (see the sticky on top of the SBF forums about balance)
--both shift PRND21, correct? Check the levers on the trans, both down, or both up = no problems.
--cooler lines, check 'em.
--cross member, measure it.
--trans length, you have that covered
--output shaft spline--you'll know when you pull a DS.
--am I understanding you that you want to/seems like you should be able to--keep your existing DS?
--backup lights, neutral safety switch, check the wiring.
PROBABLY a direct bolt in, but if you cover those things before you pull the transmissions, you'll be prepared to run for some parts, do some mods or just swap it.
Sorry I can't be of more help. Now, since these last two posts bump the thread up, maybe someone else will see it and remember the time they swapped an FMX in for a C4, or vice-versa.
--both from a 302, so it will bolt up.
--if you need to transfer the flex plate so it matches the new trans, your engines are both the same balance type, so no issue there. (see the sticky on top of the SBF forums about balance)
--both shift PRND21, correct? Check the levers on the trans, both down, or both up = no problems.
--cooler lines, check 'em.
--cross member, measure it.
--trans length, you have that covered
--output shaft spline--you'll know when you pull a DS.
--am I understanding you that you want to/seems like you should be able to--keep your existing DS?
--backup lights, neutral safety switch, check the wiring.
PROBABLY a direct bolt in, but if you cover those things before you pull the transmissions, you'll be prepared to run for some parts, do some mods or just swap it.
Sorry I can't be of more help. Now, since these last two posts bump the thread up, maybe someone else will see it and remember the time they swapped an FMX in for a C4, or vice-versa.
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From: Wingo, Ky
Both have same shift pattern. Trans cross member will have to be moved back(already another set of holes to put it in).
No wiring on either trans. The neutral safety switch is on the steering column on these years of truck.
Im worried about driveshaft length mostly. No problem switching out the flexplate if I have to.
Im not sure if both trans are actually the same length. Hard to hold the tape myself while under the truck and no help.
Thanks.
The FMX in the parts truck shifts very nice and firm. The c4 in my good truck is slipping bad goin to third. Would be great if this was a direct bolt in.
No wiring on either trans. The neutral safety switch is on the steering column on these years of truck.
Im worried about driveshaft length mostly. No problem switching out the flexplate if I have to.
Im not sure if both trans are actually the same length. Hard to hold the tape myself while under the truck and no help.
Thanks.
The FMX in the parts truck shifts very nice and firm. The c4 in my good truck is slipping bad goin to third. Would be great if this was a direct bolt in.
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Joined: Apr 2004
Posts: 34,503
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Sounds like you are pretty close here. The C4 is going to have to come out sooner than later, so maybe at that point you can do a better measure job and decide if you are headed towards a swap or a rebuild. Serving suggestion, ymmv.
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