T18 front drive shaft

[JEEPD]

I am looking to buy a 1979 CJ7 . Have not seen it yet but the owner said it originally had the T-150 Transmission but was converted to the T-18 4 speed. He said after the switch the stock front drive shaft was to short and a longer one would be needed. He believes it's the Dana 20 Transfer Case but might be the Dana 300 . Is this the drive shaft I would need Tom Wood's Custom Drive Shafts 5356501 - Front Drive Shaft for 76-79 & 81 Jeep® CJ Series - Quadratec ? And woudn't the Transfer Case make a difference?

Thanks

Edit: after looking around a bit more it sounds like there are many variations of the T-18 . So sounds like I might have to get a custom length. I believe it is the T18a

 

[Torxhead]

I would go down to a local driveshaft shop and get the existing one lengthened and balanced. The price for T.W.s shaft isn't all that bad though, but a length check would be a good idea. Looking at a u-joint list, they are the same size, but bolt up a bit different. When you test drive it, make sure the 4wd works, just to make sure.

 

[tarry99]

I am looking to buy a 1979 CJ7 . Have not seen it yet but the owner said it originally had the T-150 Transmission but was converted to the T-18 4 speed. He said after the switch the stock front drive shaft was to short and a longer one would be needed. He believes it's the Dana 20 Transfer Case but might be the Dana 300 . Is this the drive shaft I would need Tom Wood's Custom Drive Shafts 5356501 - Front Drive Shaft for 76-79 & 81 Jeep® CJ Series - Quadratec ? And woudn't the Transfer Case make a difference?

Thanks

Edit: after looking around a bit more it sounds like there are many variations of the T-18 . So sounds like I might have to get a custom length. I believe it is the T18a

JeepD

Regardless of what Transmission or Transfer Case you have the conversion process moved the "Gear Package" to the rear a little..............Hence the front will be short but also the rear may be too long.......and not have enough travel within the spline when the suspension is at full compression.

 

[JEEPD]

Thanks, for the advice. If the rear drive shaft is too long would that simply limit travle or would it be enough to cause a break ( I am a bit if a rookie here) I am wanting to hit some trails with it.

 

[Incommando]

A rear driveshaft that is too long but still short enough to fit would probably bust the ujoints as the suspension cycled. On aluminum cased jeeps like in XJ it shoves the shaft forward and busts the case but that shuldn't beas big an issue with the iron cased Dana 20 or Dana 300 . You probably have a Dana 20 as it is the most common combo with the T-18 . You probably can't by an off the shelf driveshaft as the CJ T-18 is the rarest of the jeep T-18 's and I don't think you can assure it is a CJ unit if you are not sure of the Transfer Case . A tranny from another app would make the stock drive shaft incorrect. Post pics of the parts or google pics to identify your parts
BTW: if you can find a longer driveshaft with the same yoke size it has far cheaper to have a shaft shortened then lengthened in most case.

 

[tarry99]

Thanks, for the advice. If the rear drive shaft is too long would that simply limit travle or would it be enough to cause a break ( I am a bit if a rookie here) I am wanting to hit some trails with it.

Jeepd,
Pretty much what Incommando said.................In essence they pretty much move in sequence.........so if your shortening one you need to lengthen the other and the reverse of that.

 

[Saddle Tramp]

I am looking to buy a 1979 CJ7 . Have not seen it yet but the owner said it originally had the T-150 Transmission but was converted to the T-18 4 speed. He said after the switch the stock front drive shaft was to short and a longer one would be needed. He believes it's the Dana 20 Transfer Case but might be the Dana 300 . Is this the drive shaft I would need Tom Wood's Custom Drive Shafts 5356501 - Front Drive Shaft for 76-79 & 81 Jeep® CJ Series - Quadratec ? And woudn't the Transfer Case make a difference?

Thanks

Edit: after looking around a bit more it sounds like there are many variations of the T-18 . So sounds like I might have to get a custom length. I believe it is the T18a

There are at least 7 (maybe more) Jeep versions of the T-18 . The FSJ are the ones with the long front shafts and include an adaptor between the front of the bell housing and the Transmission ; they vary in length but 5” to 7” is common. Although a CJ7 is long enough to accept the longer input shaft it is not a good idea as it does make the rear driveline short, short which can lead to vibration and premature wear on the U-bolts etc. All T-18 boxes are the same length, 11.87”, which puts the rear of the Transmission back about 3-3/4” from the T-150 stock location in a CJ (assumes no front adaptor). No matter what the rear drive line needs to be shortened and the front needs to be lengthened from the T-150 versions.

You should be able to tell more of what’s going on by crawling under the jeep for a look. Check to see if there is an adaptor between the front of the main Transmission box and the back of the bell housing. It would be best if not but isn’t the end of the world if the adaptor is there as a shorter shaft can be swapped in. As far as maybe having a Dana 300 , check at the back of the Transmission . If there is a square 1” adaptor plate between the Transmission and the Transfer Case most likely the Transfer Case is a Dana 20 with one exception. If the adaptor is round and about 3-1/2” long you most likely have a Dana 300 . The one exception mentioned above is the 1980 Scout Dana 300 which has the same Texas bolt pattern as the Dana 20 .