5spd trans bearings wining

[eltigra306]

I am looking for information on rebuilding the trans on my '87 4x4. I am fairly sure that the trans is the tk based on the stamped steel bottom cover. The questions I have are related to the od gear. There is only about 250 rpm drop between the 4th and 5 th gear drop and I was wondering if its possible to change the 5th gear to a better ratio for better fuel milage/lower rpm cruising. also I am wondering if there is a better set of bearings and sincros that I should look at getting for the rebuild.
While I am here I also have a question about my 4x4. It seams that when I get back onto pavement and don't stop completely when I take the t case out of gear something will jump or bang at about 45 to 50 mph, seams to be coming from t case or drivers side hub. Any ideas as to where to look while I have the trans out.
Thanks for any help that you can give.

 

[srteach]

The easiest way to confirm which trans you have is to check the transmission identifying page in the tech pages. Then you can get more accurate help.

If you won't follow the steps (by coming to a full stop when you disengage) to make sure you are out of 4wd, you will eventually damage something. The bang is probably the tension release from the binding of the front gears. It may be resonating back to the transfer case when it releases. Check the front hubs, the drive line, and transfer case for damage, and next time come to a full stop when disengaging.

 

[AllanD]

Steel plate bottom cover in an '87 isn't any mystery.

It's an FM145

Rebuild it?

What do I have to say or do to talk you out of it?

The FM145 goes together like a chinese puzzle and
having it JUST rebuilt is no certainty... or ever suggestion
that it won't fail the next day.

AD

 

[eltigra306]

ok if its not worth rebuilding what is the best thing to do?
Which trans should I try to replace it with?
Can you convert a t5 to 4wd I would prefer that trans to anything else I have used?

 

[eltigra306]

there is a BII with an auto I can get for a parts truck. Would I be going from the frying pan into the fire? Had an 84 BII for a few days before the trans went bad. I was quoted like 2 grand to rebuild that 1 so I don't want to get in to more stupid things that are going to cause me problems.

 

[litleblue]

Don't buy a 80's or 90's Ranger/BII with a transmisson. For that period of time they are pretty much the most unreliable part on the vehicle.

Just look at the statistics 3500 posts on one part.

 

[4x4junkie]

ok if its not worth rebuilding what is the best thing to do?
Which trans should I try to replace it with?
Can you convert a t5 to 4wd I would prefer that trans to anything else I have used?

Replace it with the Mazda M5OD. The M5OD has the slightly taller OD gear you were looking for too (of course that's not going to help your mileage at all unless you're already over 2900 or so RPM at 65MPH with your 145).
If you get the 4.0L version of the M5OD (most common), the 1st, 2nd & 3rd gears are a bit taller as well. Some 1990 2.9L trucks came with a M5OD having similar 1st, 2nd & 3rd ratios as your FM145 however, although these can be hard to find.

The M5OD is 2" longer than your 145, so some driveshaft swapping/mods will be needed.

 

[eltigra306]

Thanks for the info. Does my current transfercase bolt up to the newer mazda trans? Or should I be getting both components as well as the drvieshaft?

 

[4x4junkie]

T-cases all bolt up the same. You may need to get a different shifter though if it's a manual case (or modify the shifter you have).

 

[eltigra306]

thank you very much!!