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c4 to flathead

Discussion in 'The Hokey Ass Message Board' started by bigshawn, Aug 6, 2012.

  1. So you guys that have done the c4 to flatty swap how happy are you with it and how was it to do? I went on a long trip last weekend about 130 miles each way on turnpike and the old 2 speed ford o matic just wasnt happy howling the whole way. Worst part was not being able to keep up with my buddies ,they thankfully slowed down for me, but I know they wanted to tear it up a little . what am i in for since I have never done this before thanks guys oh by the way I have a stock rear and my flatty is a pretty stock 52 and 6volt
     
  2. jack orchard
    Joined: Aug 20, 2011
    Posts: 238

    jack orchard
    Member

    C4 won't help with top speed because final gear ratio is 1 to 1. Flathead engines don't have a lot of horsepower. Any automatic trans will sap what little power you do have. Have you considered a T5 5-speed swap? It will put the fun back in driving and will also give you a nice overdrive 5th gear. Clutch pedals aren't hard to find. Just something to be considered. Best of luck...jack
     
  3. Thanks been hearing alot about the t5 swap maybe what I nee to check into. can I keep the original rearend or do i need to change that too
     
  4. George/Maine
    Joined: Jan 6, 2011
    Posts: 949

    George/Maine
    Member

    I like my c4 running 255 mercury with 2.78 gears 205/70/15 tires.
    2000 rpms 55 mpg 2500 should do 70mph.
    I shift mine manualy most of time never miss a shift.
     
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  5. NMCarNut
    Joined: Nov 28, 2009
    Posts: 627

    NMCarNut
    ALLIANCE MEMBER

    As stated unless you went to something with less than 1:1 in top gear your top speed cruising would be no different. If you do not mind shifting a T5 would be an excellent choice. Assuming it is still original, I believe rear end ratios for Ford-O equipped cars were 3.31 standard with 3.54 optional which should be ball park where you want to be depending on tire diameter, engine HP, and how fast you want to cruise.
    You might verify your rear end ratio, ratios were available as low as 4.27 and if someone swapped something lower sometime in your car's history your cruising ability would be toast.
     
  6. ken1939
    Joined: Jul 5, 2008
    Posts: 1,546

    ken1939
    Member
    from Pittsburgh

    I have a C4 conversion and wish I went with the T5. It just wants and extra gear.
     
  7. thanks guys My rear end is original never changed
     
  8. jimbousman
    Joined: Jul 24, 2008
    Posts: 541

    jimbousman
    Member

  9. 29sportcoupe
    Joined: Jan 14, 2008
    Posts: 350

    29sportcoupe
    Member
    from arizona

    I put a c4 behind my flattie and for some reason I kept breaking parts(Not common) I soon switched to T5 and Love it. It was worth all the hassle of putting an extra pedal in. But I happen to like rowing the gears.
     
  10. Yea seems like t 5 would be it. Maybe Ill just wait till something breaks and then get a plan together . The car runs great now just wanted to get some options together for when the time comes like to be prepared thanks guys
     
  11. 29sportcoupe
    Joined: Jan 14, 2008
    Posts: 350

    29sportcoupe
    Member
    from arizona

    Now is a good time to research and start finding parts as they come available. Nothing worse than breaking down and then paying high prices for parts cause you feel the need to get it on the road fast. Plus spreading out the cost makes it easier on the back pocket, unless your one of those guys with money!
     
  12. Tank
    Joined: Nov 8, 2002
    Posts: 749

    Tank
    Member

    I put a Flat-o-matic behind mine in a '53 merc. I keep ripping the studs off the torque converter and it makes this awful sounding knocking noise when it happens. I've welded them back on 3 times now and it did it again the last time I drove it.... Everything is installed and set right, and my converter has the play in it its supposed to with the crank and all that. Needless to say I havent been real impressed with it. I'm pulling it back out.
     
  13. 29sportcoupe
    Joined: Jan 14, 2008
    Posts: 350

    29sportcoupe
    Member
    from arizona

    I was cracking flex plates with the speedway kit for a C4 to Flathead. Cracked 3 then bought a Flat O matic adapter, the starter and flywheel were not cooperating. After pulling the trans 5 times in two months I did what I really wanted in the first place. 5 speeds and a third pedal. I ended up changing the entire floor structure, F1 steering box and column(which was the best thing I ever did to my A) I have read where many guys are happy with the C4 automatic though.
     
  14. Yea spreading it put would be good and no high dollar build going on here LOL
     
  15. Bounder
    Joined: Oct 31, 2011
    Posts: 249

    Bounder
    Member

    Everyone talks about how cheap a t-5 is but I have never really seen an actual price, a $100.00 $500.00 how much. I know different areas may be different but rough guess?
     
  16. jack orchard
    Joined: Aug 20, 2011
    Posts: 238

    jack orchard
    Member

    swap meet prices in florida are $125-$250. Be sure to get the S-10 version...jack
     
  17. Shane Spencer
    Joined: Oct 3, 2009
    Posts: 2,157

    Shane Spencer
    Member

    x2 on the s10 t5. the tailhousing is in the right spot for ya. if your making decent power your gonna want a world class t5, and then throw the s10 tailhousing on it for the better shifter location. i doubt youd need a world class behind a flatty though. check out the ultimate t5 tech thread. assloads of info on there
     
  18. Shane Spencer
    Joined: Oct 3, 2009
    Posts: 2,157

    Shane Spencer
    Member

    also ~ $200 seems to be a fair price for a t5. world class is a tad more. also if you look really hard, certain s10 t5's from 1993 models only are world class. so thatd be the trans to get. pretty hard to get ahold of though
     
  19. KomoG2
    Joined: Mar 10, 2009
    Posts: 163

    KomoG2
    Member
    from Utah

    All good info guys. Im taking notes for my shoebox build. Thanks for asking the question bigshawn!
     
  20. Bounder
    Joined: Oct 31, 2011
    Posts: 249

    Bounder
    Member

    Thanks and I guess 2 bills is cheap.
     
  21. 29sportcoupe
    Joined: Jan 14, 2008
    Posts: 350

    29sportcoupe
    Member
    from arizona

    I think I gave $250 for my s10 trans(the older ones like mine have mechanical speedo). Mine came with a Dwight Bond adapter. I bought a 10.5 clutch disc from speedway that has the right splines and used a hogs head bellhousing that I had. I went with a hydraulic master and a slave cylinder to actuate the clutch fork. I moved my clutch set up to the passenger side to open up room under the drivers floor, not much room under a channels A bone. I did a ton of reading so when I did the conversion it went really smooth. My Flathead now runs down the freeway at 80 just purring.
     
  22. Forddraggin
    Joined: Jul 15, 2011
    Posts: 301

    Forddraggin
    Member
    from Lebanon,TN

    I have a c4 in my model a coupe with 50 flathead,8in.ford rearend.it does good on interstate but for lowend it kills it.wish i had a 5speed.
     
  23. This is what a adapter kit looks like........they're quite simple really, & not expensive, just make sure you get the kit with the larger flywheel. I think it's got 164 teeth. :cool: Kit includes a starter end that fits a common 1970s -1990s Ford 12V starter. You have to grind a small knotch for it to fit. All done.................:)





     

    Attached Files:

  24. fiftee6effie
    Joined: Oct 23, 2011
    Posts: 124

    fiftee6effie
    Member

    Don't waste your time with a C4 and go with an AOD Ford auto so you can keep up with your buddies!! Kits are available.
     
  25. Thanks for all the comments and input guys got alot to think
    about
     
  26. Tank
    Joined: Nov 8, 2002
    Posts: 749

    Tank
    Member

    The Flat-o-matic conversion will be coming out of my car very very soon. (hopefully tonight...) It does do well on the highway, but like others have said. Sucks down low. I will probably put it up for sale in the classifieds when I get it all apart. Adaptor, flex plate, converter, TCI trans, and the shifter. If you want to cruise, it works well.
     
  27. jack orchard
    Joined: Aug 20, 2011
    Posts: 238

    jack orchard
    Member

    Tank: pray tell, is there a clutch pedal in your future?...jack
     

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