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T18 swap

Discussion in 'Intermediate CJ-5/6/7/8' started by LarryD, Oct 26, 2008.

  1. Oct 26, 2008
    LarryD

    LarryD Member

    Gallup NM/ 4 Corners
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    I am seriously thinking about swapping in a T18. I recently saw a Scout T18/Dana20 for sale. On the Novak site it states the Scout Dana20 is basically the same as Jeep Dana20, but the International T18 is almost useless for swapping into a Jeep. I was reading the Jeep Rebuilder's Manual today and he used an adapter off a Scout T18 to adapt from the Ford T18 to Dana20. Since those aftermarket adapters are $450-500 should I pick up the Scout T18 just for the adapter? Does It just bolt on the T18 case or will I still need a different output shaft?
     
  2. Oct 26, 2008
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    I would. No personal experience, but Nick (member nickmil) has written about this before. You need the adapter and the mainshaft from the Scout. Nick writes that you have to drill and tap some holes, and plug some existing holes in the case or adapter. Since you need to change the mainshaft (complete disassembly), you may as well rebuild the Ford T-18 in the process.
     
    Last edited: Oct 26, 2008
  3. Oct 27, 2008
    jeepdaddy2000

    jeepdaddy2000 Active Member

    Eagle Point oregon
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    I did this swap. You will have to gut the main shaft from the Ford casing to install the Scout mainshaft. Drop the rear bearing in the back of the casing as a template, place the adapter over it and drill/tap the mounting bolt holes. Re-install the mainshaft and bolt on the adapter. I'm pretty sure the Ford housing will bolt to your existing bellhousing and the input is compatible with your existing clutch (mine was adapted to a Dauntless).
     
  4. Oct 27, 2008
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    On a '75 with a T-14 or T-15, you'll need a different bellhousing to fit a Ford transmission. The bell from a T-150 (76-79) or T-176 (80-on) CJ will work.
     
  5. Oct 27, 2008
    CJ-X

    CJ-X Member

    Ohio
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    Can you use the same parts from a Scout T-19? And gain the synchro 1st?
     
  6. Oct 27, 2008
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    I'd guess you can... I recall something about that in an earlier thread.
     
  7. Oct 27, 2008
    NorCoJeeper

    NorCoJeeper Member

    Ft. Collins CO
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    In my experieince, ponying up the $$$ for the Novak adpater and T-18 output shaft, and a T-18 rebuild kit, was worthwhile. Around here, Scout parts are damn tough to find. This also helps guarantee you get a good output shaft as most Scout parts are going to have a ton of miles on them by now.
     
  8. Oct 27, 2008
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Nope. The guts are different for the most part and the case and shift cover are different. The input shaft is the same and one or two of the speed gears but that's it. The T-19 main shaft has an extra snap ring groove on one of the other grooves is in the wrong location. The T-19 cluster gear is different as well. It has a helical cut first/reverse drive gear built into it while the T-18 is spur cut. Other issue is the T-19 adapter doesn't have a provision for a mount as the Scout T-19 had a mount point cast into the main case. Also, on the T-19 the reverse idler shaft and cluster gear shaft are in different locations than on a T-18. Been down this road before....

    The easiest way to use the scout T-18 would be to gut it and use the main shaft and adapter in a Ford T-18 case. You will need to drill and tap 6 holes, as Jeepdaddy said, use the rear main bearing to locate everything centered. The bottom left stock hole in the Ford case will need to be plugged. A hex drive set screw works great for this, 1/2" iirc. Sometimes the adapter and gasket doesn't quite cover this hole and the leak will drive you nuts trying to figure out where it's coming from. Basically, use a Ford T-18 and put in the Scout mainshaft and adapter and be done.

    As mentioned, the bellhousing will need to be switched to a '76 up unit. Timgr mentioned one with a T-150 or T-176, those are the easiest as the Ford T-18 bolts right up. You can use one from an SR-4, T-4, or T-5 but will have to drill and tap the holes. The bosses are cast in and many already have a pilot from the factory for doing this so no issues there.

    The Scout 2 adapter "clocks" the transfer case slightly different than the Jeep unit does, not much, but enough that it can cause some shifter housing interference to transmission case on some transfer cases. No big deal, couple minutes with a grinder or sander takes care of it, but something to be aware of.

    You will also need a new pilot bushing. PartsMike, R&P, Novak, AA, etc. all sell the correct bushing that mates the Ford pilot to the AMC crank. If are using a T-14, T-15 you will need a new clutch as well.

    Drive shaft mods will be necessary as will floor pan mods and moving the crossmember. Having said all this, it's one of the best mods you can do to a Jeep that will see trail use IMHO. Right up there with disc brakes and power steering.

    If you can pick up the Scout stuff cheap, then I'd say go for it as you could save some real coin on the adapter kit and use the other money to rebuild the transmission as it's likely to need it. Pay close attention to the teeth on first/reverse as it's common to see them damaged from grinding into gear, look close at the inside of the cluster gear where the needles ride and the thrust surfaces on both the gear and inside the case. I'd be willing to bet the cluster gear shaft is worn so plan on one of those. Not very expensive though.
    Before purchase I'd pull the cover and make sure there hasn't been water sitting in the transmission. If so, the main shaft could be rusted inside the gears and could be problematic.
    The Scout 2 T-18 could be a 4 to 1 first. If so little will be useful to you other than the main shaft and adapter.

    Make sure the trans is in fact a T-18 and not a T-19. The T-19 was far more common in Scouts and almost all of them were 4.02-1 versions. If it is a T-19 it won't be any use to you unless you want a 4-1 first gear but will be much harder to adapt to your AMC and most likely more expensive. Most people prefer the 6.32-1 version....

    A way to tell a T-18 is the passenger side of the case where it meets the top will be flat the length of the case with no bulges. On the driver's side it can be parallel to the passenger side or may have a bulge at the rear if a late model. The T-19 will "flare" out towards the rear of the case where the top meets the case on both sides.
     
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  9. Oct 27, 2008
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Nick, the question I think you are answering is "can you use the Scout T-19 mainshaft and adapter to adapt a Ford T-18 to the Dana 18/20?" However, I understood CJ-X to be asking if you could use the Scout T-19 to adapt a Ford T-19 to a Dana 18/20. If you could do that, you'd still have the problem of no mount on the Scout T-19 adapter, which I'd think you could overcome somehow.

    BTW your previous post will be cut and pasted into my notebooks. I know you've posted some of this before, but it's good info to get all at once - thanks!
     
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  10. Oct 27, 2008
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Ahh, I see.

    You can do the same with the Scout T-19 to Ford T-19, in other words use the Scout T-19 output shaft and adapter in the Ford. Same rules apply though as with the T-18 conversion. You definitely can't use a T-18 adapter on a T-19 or vice verse because of the difference in location of the reverse idler and cluster gear shaft. The adapter has a pocket for these and the different location creates interference issues.

    What I've seen some do to overcome the mount issue is to fabricate a mount on the bottom of the T-19 adapter plate similar to how the T-18 is set up. The adapter is cast steel so can be welded to with proper precautions being taken.

    Glad to help...
     
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  11. Oct 27, 2008
    LarryD

    LarryD Member

    Gallup NM/ 4 Corners
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    Thanks Guys.
    This is why I really like this forum, great information!
    I had planned on the replacement bell housing but those don't seem as if they will be a problem, I have seen several on E-Bay. The transmission and adapter seem more difficult and pricey.
    So if I understand the Scout 4 speed won't necsssarilly be a T18 and if a T18 not necessarily a wide ratio. I am guessing If a T18 or T19 I can use the adapter But if a T19 not the main shaft. What about if it is a T18 close ratio, will the main shaft be the same as a wide ratio?
     
  12. Oct 27, 2008
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Correct.

    [/QUOTE]
    I am guessing If a T18 or T19 I can use the adapter But if a T19 not the main shaft. What about if it is a T18 close ratio, will the main shaft be the same as a wide ratio?[/QUOTE]

    Wide ratio or close ratio doesn't matter on the main shaft or adapter. You cannot swap a T-18 shaft into a T-19 or vice verse. Same with the adapter. You must keep T-18 with T-18 and T-19 with T-19.
     
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  13. Oct 27, 2008
    LarryD

    LarryD Member

    Gallup NM/ 4 Corners
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    I am guessing If a T18 or T19 I can use the adapter But if a T19 not the main shaft. What about if it is a T18 close ratio, will the main shaft be the same as a wide ratio?[/QUOTE]

    Wide ratio or close ratio doesn't matter on the main shaft or adapter. You cannot swap a T-18 shaft into a T-19 or vice verse. Same with the adapter. You must keep T-18 with T-18 and T-19 with T-19.[/QUOTE]

    Thanks for clarifying that. I guess the reason I assumed the adapters were the same as on the Novak site it seemed the T18 and the T19 were very similar.

    Thanks for the information.
     
  14. Oct 27, 2008
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    The aftermarket companies that build the custom adapters for T-18's and T-19's build the adapter itself to fit either so they don't have to build an adapter for each application. Cuts costs and inventory. They also build them normally to fit the Ford case so there is no drilling and tapping and plugging to do. Novak, R&P, and AA all do this. The shaft however simply won't interchange. :beer:
     
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  15. Oct 27, 2008
    CJ-X

    CJ-X Member

    Ohio
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    Good information. I need to copy much of the info. You know, you think will remember simple stuff, but you forget. I ended up doing it different than most. It went like this:

    A) Started with (1975) jeep 4:1 factory Jeep T-18 behind 6cyl, +model 20. *That T-18 then had 1" adapter plates on both ends.
    B) Switched to chevy engine, so I used a 4" AA adapter between chevybell housing and 4:1 jeep T-18.
    C) Wanted 6.32:1, and wanted to eliminate the chevy adapter. So I used these parts....
    ....1) the jeep t-18 case
    ....2) The jeep main shaft.
    ....3) All ford t-18 gears and input shaft.
    ....4) Chevy bell housing, but had to weld in more material to add a different bottom hole on passenger side. Made a weird bracket to accomodate the bottom hole on the driver side.
    ....5) Added a piece of pipe to the advance adapters bearing retainer so my throwout bearing would have a place to slide on.
    ....6) Used chevrolet 12" pressure plate, and slightly smaller Ford clutch disc.
    ....7) Fabbed a GM Hydraulic slave cylinder, but that is a different story.
    .
    I did it this way simply because I was just working with the parts I had, and I did not want unnecessary adapters so everything would be as short as possible. I have always wondered if there was a better way. Perhaps using an expensive blowproof chevy bellhousing. Question; Could I have done it much differently? For some reason which I forget, the Ford T-18 housing would not work for me.

    P.S. Don't mean to hi-jack, but I think the original question has been well answered.
     
  16. Oct 28, 2008
    NorCoJeeper

    NorCoJeeper Member

    Ft. Collins CO
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    The adapter does require drilling and tapping the transmission case on some years of Ford transmissions. I don't know where the year break is, possibly when Ford went to the standard New Process 6-hole tcase adapters, but my 1981 T-18 required plugging one hole and drilling another.
     
  17. Oct 28, 2008
    nickmil

    nickmil In mothballs.

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    Very interesting. Never run into that before. All the Ford T-18 cases I've run into were 4 bolt pattern where the adapter bolts on. The adapter to transfer case end is different for sure for the different transfer cases. Can you give an application or pics? I'm very interested in this anomaly. I know the NP-435 used different bolt patterns depending on 2 or 4 wheel drive applications. The aftermarket adapters are designed to work with the standard Ford 4 bolt pattern. Never run into the aftermarket adapter that required redrilling a hole for the Ford T-18. I'm not saying you're wrong at all. I'm really interested in this.
     
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  18. Oct 28, 2008
    nickmil

    nickmil In mothballs.

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    You can elongate one hole and add some material to the front of the case and drill a hole in the material added to bolt the Ford case to a GM bellhousing. The front bearing retainer needs machining for the GM throwout bearing to slide on. The outside diameter of the bearing retainer needs machining if using a GM bellhousing with the small indexing hole or a ring added if using the larger indexing hole bellhousing.
    You can also use a scattershield to bolt the Ford case to a GM motor.
     
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  19. Oct 28, 2008
    NorCoJeeper

    NorCoJeeper Member

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    It's actually in the Novak instructions for the Ford T-18 to Jeep Dana 20 transfer case adapter. My application is a 1981 Bronco / F-150 T-18 to a stock (AFAIK) 1975 Jeep D20 'case. The transmission does have 4 bolts on the adapter end, but one is offset by an inch or so IIRC. It's the lower right as you look at the back of the transmission. The adapter comes with three 9/16" or so socket head bolts for three of the transmission adapter holes, and one that is 7/16" or so for the hole that must be drilled. I believe the kit came with a socket head plug for the original hole that had to be relocated.

    Another thing that was strange on my setup is that one of the adapter to tcase holes was so tight against the transmission that the bolt had to be installed into the adapter before the adapter was installed to the transmission. It's a nice detail they leave out of the instructions. That bolt also had to be started into the tcase first because if the others were installed I couldn't get a wrench on the bolt head. It's very difficult to get that bolt tight since you can't get a full swing on the wrench.
     
    Last edited: Oct 28, 2008
  20. Oct 29, 2008
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    The bolt thing is common to all the Ford case to 18 and 20 transfer case swaps. I try to use a reduced head size bolt like a header bolt there so I can get a smaller wrench in there. Makes it much easier.

    I've never run into what you have. I've done a couple hundred of these conversions using stock adapters, AA, Novak, and R&P adapters and have never seen that. On the stock adapter you have to plug the bottom left hole but other than the stock adapter-redrilling the case I've never had to re-drill a T-18 case or adapter for an aftermarket adapter.
    Must have an oddball case there or something or Novak redesigned their adapter since the last one I installed. Learn something new I guess.
     
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