T18 Questions..

Discussion in 'Intermediate CJ-5 and CJ-6 Tech' started by Sierra Bum, Nov 5, 2017.

  1. Nov 5, 2017
    Sierra Bum

    Sierra Bum New Member

    The High Sierra
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    First, sorry if this has been covered somewhere. There's lots of confusing info out there on this.

    Situation: I'm in the market for a jeep. I've always been into the short nosed cj5's but am warming up to the longer wheel base as I've seen a couple particular intermediate year jeeps that I like (258 engine). I want a granny gear 4 speed. I've had a couple sellers now tell me "oh yeah its a granny gear T18", only to find out its a close ratio T18. I know case markings are not really reliable identifiers. So my understanding is, with all the different versions of the T18, the close ratio model that is common in the intermediates has a spacer/adapter at the bell due to the longer input shaft. Is this correct? If a guy swapped in a 6.32 model T18 then, it would not have the spacer against the 258 motor bell-housing? How about the 304 or a 360?

    My reason for asking this is I'd like to ask a seller to send me pictures of the tranny and bell housing so I can confirm his claim. I want to get as much info (pictures etc) as I can because I've gotta drive a ways to check anything out and jeep owners don't always know much about what they've got.

    Thanks in advance
     
  2. Nov 6, 2017
    tarry99

    tarry99 Member Sponsor

    Northern California
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    Both Close and Wide ratio Jeep version gear boxes are the same length...........and both have the long input shaft.....If it was a Ford version T-18 short input shaft and swapped in later it could have no adapter and still be either a close or wide ratio............................If you can drive it.......you will know if its a 6:32:1 low gear...........If it's not running then pulling the shifter cover off the top of the tranny may be the only other way to confirm and what your looking for is 17 teeth on the forward most gear on the input shaft that meshes with the counter shaft below which will equal a 6:32:1 ratio.....Also I believe the PTO cover on the Jeep model is on the drivers side while the Ford version is on the Passengers side..............
     
  3. Nov 6, 2017
    timgr

    timgr Jeepin' Nerd Sponsor

    Medford Mass USA
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    Realize that there was no wide ratio T-18 in a CJ until 1977. It was only offered through 1979, so 3 years only.

    There was never a T-18 304 CJ before 1977, and its existence is questionable after 1977 (parts book says not). The CJs never got the 360 or 401 from the factory.

    There was a T-98 wide ratio 4-speed available domestically through 1971 only with the F134 engine. The close ratio T-18 was offered with the 225 V6 in 1971 and maybe earlier, but no wide ratio. I expect these V6 T-18s use the Buick bell with a plate adapter.

    Starting in 1972, Jeep offered the close ratio T-18 with the 232 and 258 in the CJ-5 and Commando. At this time, Jeep was using a single bell housing for all applications, the "T-15 bell." For the T-18s, there was a plate adapter between the transmission and the bell, and the input shaft was long enough to extend through the plate and bell. This continued through 1975.

    The 1976 CJ uses a dedicated bell without the plate adapter, but it's still the close ratio T-18.

    So if you have a CJ that is NOT a '77-79 and the seller claims it's a wide ratio transmission, there are only two ways that this could be true. First, it's been converted to a T-18 using a FORD (or JEEP with a FORD input shaft) wide ratio T-18 and a conversion kit. This conversion uses a Ford pattern bell and no plate adapter. The other possibility is that it was converted using a wide ratio T-18 from a '71ish-79 J-truck or Wagoneer (full size Jeep, FSJ) with a 258 engine. The FSJs with a 258 used the same plate adapter and T-15 bell that the CJs did, but they got a wide ratio transmission. Donors for this transmission are scarce, so this conversion is rare - I only know of one Jeep that was set up this way, and the owner had access to a dealership parts department back in the day and picked new parts, not from a donor. Jeep PNs are 5351416, 7439 and 8285 and WG 13-01-000-040 or 192.

    So I would assume that every pre-1977 258 T-18 CJ I found has the close ratio transmission. The only unambiguous external markings for close ratio will be the Jeep PN on the tag on the top of the transmission, usually 999636, or 5355010 for 1976. Not visible unles you remove the floor plates. You can also take the transmission shift top off and count teeth on the input gear.

    If I found a nice 258/T-18 CJ I would not pass it by, even if it were a close ratio transmission. It's still a desirable combination, owners in the day that had them really liked them, and they were popular. '72-75, that's a great drive train. If you find one with 4.27 axles, that's even better.
     
    Last edited: Nov 6, 2017
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  4. Nov 6, 2017
    oldtime

    oldtime oldtime

    St. Charles,...
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    Tim's post is exceptional and follows exactly what I have always suspected as fact.

    One can identify ratios for any make of T18 be it Ford, Jeep or I.H.
    Narrow Ratio (NR) T18 always has a 23 tooth maindrive gear while Wide Ratio (WR) always has a 17 tooth maindrive.
    NR @ 4.02 vs WR @ 6.32
     
  5. Nov 6, 2017
    oldtime

    oldtime oldtime

    St. Charles,...
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    Furthermore one might mention that 1979 Jeep CJ is the only year available with the late design T18.
    The late design T18 has a notably different case than all previous T98 and T18 cases.
    The left rear transmission bulge is distinctly different.
    It has distinctly different shift tower with aluminum shift forks.
    Reverse gear is over and down; not over and up as the previous pattern.
     
  6. Nov 6, 2017
    Daryl

    Daryl Sponsor Sponsor

    Bonney Lake, WA
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    I would add that if it is going to be regularly street driven then the 4:1 transmission is more desirable as you can actually use first gear to start out in.
     
  7. Nov 7, 2017
    hudsonhawk

    hudsonhawk Sponsor Sponsor

    Dallas, TX
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    For my 72, I was lucky to find a FSJ wide-ratio T-18 and did the ford input shaft swap on it so I did not need the extension plate between the housing and the tranny. I used a re-drilled bell housing to mate it to the 258. The nice thing about the FSJ transmission is that it came with the adapter plate that allowed the Dana 20 to bolt direct to it. I had to modify shift linkages and some other things to make it all work. I also had to use a different clutch cylinder than came on the CJ. All together it was just slightly longer than the stock transmission/t-case combination. With 4.56 axle gears, terra-low gears in the t-case and the 6.32 1st in the transmission, the crawl ratio was 91:1 and it would literally idle up almost any obstacle.

    I sold the transmission/t-case to a member in California when I parted out my CJ. As far as I know it is still in use.
     
  8. Nov 7, 2017
    hudsonhawk

    hudsonhawk Sponsor Sponsor

    Dallas, TX
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    Yeah 1st is way too low for street driving. I used 2nd all the time to start.
     
  9. Nov 7, 2017
    Sierra Bum

    Sierra Bum New Member

    The High Sierra
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    Wow, thanks for all the thoughtful, informative posts you guys. Lots of valuable insights here. Tim, that clears up alot for me. Thanks for sharing all that knowledge. My future, new-to-me jeep will not be a daily driver or anything but it will see some road duty as I want a rig I can drive around too. I live in a rural mountain town and can literally hit jeep trails out my back door. I don't want an extreme crawler but a classic, capable trail rig that I can take care of and explore and adventure in the Sierra. In my last CJ, a 68', I put in an sm420 and loved the 84:1 final ratio. Whatever I end up with I'll ultimately aim for a low crawl ratio coming from a granny-gear 4 speed. Following the evolution of these CJ's and learning about how folks build and customize them is fun to learn about. I like to hear about all the creative solutions.
     
  10. Nov 12, 2017
    tiptoptune2

    tiptoptune2 New Member

    Breckenridge...
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    i have a similar set up as hudsonhawk, T18 low first, terra low, 4.56, 35 tires and it works well for me here in Colorado where i live in a similar environment with trails out the back door and use my jeep as you intend to. I have a buddy with same 225 engine as mine, except he has fuel injection, the low first T18, std D18 gearing, 5.38 gears, 35 tires and his does not seem to be as low as my combo. I went 4.56 rather than 4.88 or lower so would have stronger gear set having one more pinion tooth in contact with ring. I have often wondered if the lower gear in the tc might twist or break one of the tiny output shafts, but been good for 11 years or so and it gets used pretty hard. I start in second on flat and use first if uphill while on the road. Good luck.
     

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