How do i make this 4spd and 9" work for me?

Discussion in 'Classic Mustang Specific Tech' started by 351pacecar, Dec 3, 2003.


  1. 351pacecar

    351pacecar Founding Member

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    I got a '70 fastback parts car (or maybe another project) that has a rug-ad toploader 4spd ('68 390GT) a funky hurst z gate shifter, and a scattershield that is super thick steel and someone who saw it mentioned it looked like a converted industrial piece (i dunno). Also has a strange built 9" rear end.
    I don't know what input shaft the tranny has on it but I want to put it on either a 351w or 5.0 (same parts for both I assume) how do I determine what parts I need, and are they available? Also the rear end has ridiculously long wheel studs for some reason, and it has a spool and gears that are supposed to be higher than I would want in my Jeep. I suppose I can just pop the studs out if I need to, but should I just replace the whole center section with a complete nother one and sell this one, or should I just replace the spool and ring and pinion? (assuming the gears are as high as they say)
  2. D.Hearne

    D.Hearne Banned

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    First off that 390 Toloader 4 speed has a shorter input than the other small block Toploaders, and as such will not work with most small block bell housings. The input is the same diameter as the small blocks though. So unless you can find a longer pilot bushing, the input won't reach into the bushing, leaving it unsupported ( hard on input bearings) The rear wheel studs are normal for a drag car. you should be able to replace them with shorter ones. Unless you really like your tire dealer, that spool will have to go. The gear ratio is most likely something you also wouldn't want to run on the street so, It would be a good idea to sell the whole "chunk" and get one that's more streetable.
  3. 351pacecar

    351pacecar Founding Member

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    Anyone have the measurements to tell me if thats still the 390 input shaft? Nothing else on the car is original so why should that part of the tranny be. The car is an F code, but the P.O. who got it without an engine and never fixed the car (in 20 years) thought it may have had a 351c in it when it was raced, and the solid motor mounts and very odd scattershield dont help me determine that either.
  4. D.Hearne

    D.Hearne Banned

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    the very front snout on the input ( the part ahead of the splines) on the 390 Toploader is about 1/2-5/8 inches long. On the other smallblocks, this part is about an inch to 1 1/8 long. I doubt the input was changed, the trans has to be completely disassembled to do so. If that Toploader has the short snout, it can be replaced with a longer small block input.
  5. 1320stang

    1320stang Founding Member

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    Email me a pic of the scattershield. If it is for a 390 and is steel and not cast iron, I have a used steel Lakewood that will fit behind the SBF I'd trade you for. I have a 390 I'm going to put in my '63 Fairlane and it has a different bellhousing bolt pattern.

    Does the shifter have the rods with it? And the tabs that attach them to the tranny? I bought one of those but didn't get the rods.

    Count the teeth on the ring gear and the the teeth on the pinion gear to tell what gear ratio it is. For example; 36 ring gear teeth divided by 7 pinion gear teeth equals a 5.14 gear ratio.

    Larry
  6. 351pacecar

    351pacecar Founding Member

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    I just picked the car up and it immediately went into storage on a local farm so I never bothered to check the rear gears, I'll get to it in the spring. I can go get the bellhousing and meausure the input shaft on the tranny. I would assume the shifter is complete since the tranny is still bolted in the car with the rest of the drivetrain and the shifter is attached to it. Its not in the greatest of shape and seems kinda stuck but I think I could get it working again.

    Those input shafts are still available then? Would the throwout bearing retainer need to be changed too?
  7. 1320stang

    1320stang Founding Member

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    David Kee Toploader Transmissions will have the input for sure, but being you will be street driving it and not racing it, I'd just get the extended pilot bushing that David spoke of. Another option I've seen is to have someone weld an extension onto your input. You'll have to remove the input so that it can be chucked up in a lathe so that it can be trued after its welded. I've seen this done in drag cars and I believe this is the way Liberty used to do it years ago, but I think in a street driven car, it would be fine. Personally I'd change it out, but depending on your wallet, I'm just trying to give you other viable options.

    And no, the retainer wouldn't have to be changed, the 390 tranny has the same diameter input shaft, the part for the pilot bushing is just shorter. Now it may be different inside the tranny, but if you pull the retainer of yours and a SBF tranny, you shouldn't notice any difference.

    Larry
  8. 351pacecar

    351pacecar Founding Member

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    Looks like the scattershield will work for me afterall. Its definetely steel and extremely heavy, it seemed to be drilled for several different engines since it fits the 351w that i had sitting in the garage but only used half the holes. Both the tranny and bellhousing also seem to have been drilled for an extra set of bolts so I will have 8 bolts holding them together and its double layered on the scattershield side around the holes.

    The tranny does look like it is all original 390 setup though (3/4 inch snout in front of splines), so ill hafta do something with that.

    Edit: Umm, I think I got a better deal on the car than I though, it seems that I have a lakewood bellhousing that sells for $300. Seems its listed at 48 lbs, I thought it was a tad bit heavy for a bellhousing.
  9. D.Hearne

    D.Hearne Banned

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    1320stang--- you can order the shifter linkage from summit. But first go to Hurst's website and look up the part # for the shifter installation kit you need. Then order it from Summit. The installation kit contaims everything you need to mount the shifter body and stick to your transmission ( linkage rods, shifter arms for the trans , bushings, pins, etc. The only thing that's not there, that I prefer, is the steel shifter bushings. The kit comes with nylon ones.
  10. 1320stang

    1320stang Founding Member

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    Well, the scattershield shouldn't fit both a 289/302/351w AND a 390. If it's been modified, it won't pass SFI specs to race if the track is very meticulous. If it's a SBF bellhousing, yeah, they sell for that new, but they sell used on Ebay for $75-$125 typically. If it's clean, or never been used, I've seen them up to $200. A 390 (FE) bellhousing goes for a little more, $125 to about $200, there are quite a few on Ebay during the winter for some reason.
  11. fastback brian

    fastback brian Founding Member

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    I paid about 90 bucks to have an input shaft extended but it was a big spline input so i couldnt just swap it out. All those extra hole in the bell housing will get a simple bolt and nut to complete the assembly.

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