1978 CJ7 transmission replacement - JeepForum.com
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post #1 of 7 Old 07-01-2009, 10:34 PM Thread Starter
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1978 CJ7 transmission replacement

I am really new when it comes to jeeps, especially transmissions. I am looking at buying a '78 CJ7 with a 3 speed transmission, which i found to be a t150. I want to put a 5 speed in it so I have the OD gear for road cruising. What transmissions would work with the least ammount of modification and money spent?

P.S. It is a 78 CJ7 with a 258 ci i6

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post #2 of 7 Old 07-01-2009, 11:34 PM
new cal shooter
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I have the T-18 1st gear is for crawling only, then 2-4 is for road driving, I like it alot, have it in my F-250 also, very good transmission in the manual form, good luck, if you can find one already done GO FOR IT, working on your jeep means not driving it as much
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post #3 of 7 Old 07-01-2009, 11:48 PM
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I just swapped a ford t18 into my 82 CJ7. If you're dead set on an overdrive then the T5 or AX-15 would probably be the cheaper options, but neither is really that strong. My Jeep had the T5 but it couldnt take the abuse of driving off road. The Ford t18 will bolt up to your current bellhousing, but you would need to get an adapter. Go to novak-adapt.com, they have tons of good info transmissions, engines, transfercases, and adapters. I got my T18 to Dana 300 adapter from them and it is awesome.
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post #4 of 7 Old 07-02-2009, 12:29 AM
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I'd avoid the T5. Another T18 here and I'm fine without the OD (granny is worth the trade).

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post #5 of 7 Old 07-04-2009, 08:14 AM
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What about a T-176? Stronger than a T5 or AX-15, although it still does not have the OD (4 spd).

MINE: 1995 YJ/2.5L/115K/Completely Stock
MY DAD's: 1978 CJ7/ AMC 360 .030" over/ Motorcraft 2100/ Edelbrock Performer/ Proform HEI Ignition/ Hedman Headers with dual Flowmaster 40's/ Taurus Fan/ FK-35 Control/ Painless Harness/ Rebuilt T150 & Dana 20/ 4" Lift/ 31" Procomp Mud Terrains/ All Fiberglass. (SOLD)
MY BROTHER's: 1996 ZJ Limited/5.2L/117K & Completely Stock.(SOLD)
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post #6 of 7 Old 07-04-2009, 02:39 PM
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Originally Posted by CGITCH View Post
I want to put a 5 speed in it so I have the OD gear for road cruising. What transmissions would work with the least ammount of modification and money spent? P.S. It is a 78 CJ7 with a 258 ci i6

NEXT: Would be to swap a T5/Dana300 combo out of a late model CJ7 into your rig. While you at it get all the other stuff from the donor vehicle.

NOW: If you don't mind getting into a bunch of modifications, the NV35xx series 5spd or the AX15 5spd is the way to go with your 258. The NV4500 is a bit of overkill for an I6 CJ, IMHO.

HOWEVER: You will end up adapting them to your Dana 20 transfer case. And you will need to modify the trans mount on the skid plate. Or just replace the crapo OEM skid with a custom fab'd crossmember/skid combo. Driveshafts will need to be modified, as the 5spds are longer than the T150 3spd. Driveline angle may need adjusting also.

THEN: There's the whole question about what size tires you plan on running, as an O/D is gonna be pretty useless on a lapped out 258 with 35" rubber, unless it's geared properly.

"In the end...It's all Hack."
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post #7 of 7 Old 07-04-2009, 10:36 PM
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depending on the tire size and gear ratios, the t150 does rather well at 60-65 mph. i was cruising today at highway speed and it wasn't straining a bit with my 31's.

i'd say stick with the 3 speed for a few months and see how it works out for you. its a very strong gear box and i personally really enjoy the feel of it. its like driving a big truck, long shift throws and you can feel each gear engaging when you shift. nothing like driving a TJ IMHO.

'06 Wrangler SE, soft top, hard doors, 2.4L, rolling completely stock and unmodified for the short term...
'10 Wrangler Sport, soft top, hard doors, 23S package, Teraflex 2.5" spring lift, Spidertrax 1.5" wheel spacers. Sold.
'79 CJ-7 Renegade, 258 I6, T150, D20, D30/AMC20, 2.5in Rancho lift, 31x10.5 AT's, TeamRush upgrade, flush tail lights - Sold :'(
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