t90 trans sycro question?

[glenn beck]

has anyone ever heard of a sycro first gear or a conversion for a t90.
first gear is great in the mud and second gear is great at low rpm on the trail to the flag ponds. the problem is there are deep muddy spots on the trail so i have to stop to select first gear as its not sycro-ed and i dont have the hp to stay in second. maybe they made a trans that would fit with sycro first or a grany transmission that would make second the same ratio as first on mine? any ideas

1969 cj5
f134-t90-t18
dana 41 rear
5.38 gears
40" military tires

 

[Saddle Tramp]

I had your set up once. I think you need to go to a T19 to get the syncos. I would find a used Warn or Atlas overdrive if you don’t have one. That will give you some additional gearing options that won’t require you come to a full stop.

 

[glenn beck]

t19 seems like the best option except from what i have read about them being weaker than the t90. will i have to get adapters to match the f134 or is there a certain type i should be looking for. as for the overdrive thats on my wish list but it seems a very rare and exspensive part to find.

 

[Saddle Tramp]

The T19 is going to be a much stronger transmission than the T90. I know from experience the T90 will not hold up behind a V8 and a T18/19 will.

As far as getting a T19 to bolt into your jeep the waters get a little muddy. I think you need to find bell housing for a 134 to T98. These were used in the latter years of the 134 run ending 1971. I don’t believe the 134 bell housing bolt pattern is the same as the AMC pattern that began with the AMC I6s & V8s starting in 1972. (Someone please correct me if I am wrong here) If you can not find the T98 bellhousing you will need either an adaptor or a special bellhousing.

On the other end of the transmission at the Spicer 18 x-case I think you may have another problem. The input hole used on the 18s were of two different sizes, a small hole and a big hole. The big hole was used towards the end of the 18 run that stopped in 1971. It is unclear if the big hole was ever available with the 134 and generally believed that that it was not. The T19 is going to require a large hole 18. So, in order to do this swap you may need a new x-case too.

The T19s came in IH trucks and Fords. Finding one with the wide ratio (6.32) first is going to be the problem as the majority of the IH were close ratio (4.0) first. I’m not saying they can’t be found but you may need to kiss a few frogs to get the one you want. I am not sure about the Ford versions and what the availability of the different ratios was. Any T-19 that was mated to a Dana 20 x-case will fit a wide hole 18.

To me the hunt for parts is half the fun; good hunting.

 

[glenn beck]

thanks for the advise. im going to pop over the father-in-laws and raid his scrap pile to see what he has and go from there. with the cost of adapters i might even consider finding a engine/t19 trans combo that way i will have more power and the sycro box.

 

[Ggg]

Another option is to change t-case but keep the t90. Find one with a better low range and you will be able to pull your second gear. But that may pose some driveshaft issues.

 

[HiHood]

Mine has the warn OD unit behind it. They are pretty pricey even used.

 

[Saddle Tramp]

Another option is to change t-case but keep the t90. Find one with a better low range and you will be able to pull your second gear. But that may pose some driveshaft issues.

Options here really come down to the Spicer 18 x-case because of the off set rear end unless the whole drive train is changed. I have seen people put the axel at an angle (center x-case output with off set differential) but I'm not comfortable with that set up myself. Even though the T90 is a weak link in the drive train chain from the get-go you could put a Teralow (or something equal to that) in the x-case and give you better low range that might work with 2nd. Couple that with a over-dirve and it just make it all palatable.

I guess it comes down to where do you start and where do you stop.

 

[Ggg]

The offset driveline angle does pose some issues but none that are insurmountable. There have been a few OEM drivelines that were offset on two planes, you just need to be certain to get the angles correct.
I have no experience with the Warn OD so I may be wrong here, but does it work in 4wd or just 2wd?

 

[glenn beck]

thanks for all the replys. after looking at what my friends have laying around i realise that getting a sycro first is going to lead to changing most of the drive line. i found a t19 joined to a t20 transfer (doesnt have the low first but is sycro) then i thought if i have to add a adapter i might as well just get a 6 cylinder then i might as well change the rear axle to suit the T20 center line then change the front axle to match the gearing. i have a dana 60 and a 44 that would work so thats the motor-transmission-transfer-and axles-drive shafts-the list goes on and on.
the trouble is i realy like the F134 as it sounds like a tractor and the T90a transmission is a fun odd ball with reverse being in the same place first should be. the T18 is cute and i like the dana 41. so im going to leave the jeep/golfcart alone and go buy another jeep to play with maybe a old cj7.

 

[Saddle Tramp]

I have no experience with the Warn OD so I may be wrong here, but does it work in 4wd or just 2wd?

The Warn overdrive can be used in either 2 or 4, high or low.

 

[Ggg]

ST Thanks for the info