ok, here's the truck/transmission in question:
'89 CTD W-250, 3-speed auto (727?), D61 front, D80 rear (previous owner swap), 3.08 gearing, completely stock engine (for now), 3" straight pipe exhaust

Ok, this may be long, so i apologize now:

Trucks been running/driving perfectly, shifting just fine, no weird noises or ANYTHING.

3 weeks or so ago, it started to "pull" when at a stopsign/stoplight. Like a manual transmission does when the clutch isn't adjusted correctly, letting the clutch "grab".....didn't do this all the time at 1st, and really not THAT noticeable. What caught my attention was the lower RPM in gear at idle while at a stopsign/stoplight and the fact that as soon as my foot started letting up on the brake pedal she'd start creeping forward.

Like i said, didn't do it all the time though, more when it was really hot outside or after driving non-stop 200 miles down the highway.

fast forward to last friday:
I get off work and head home in approx 85* heat.....she's "grabbing" again.....i pull away from a stopsign, she shifts perfectly 1st to 2nd, 2nd to BANG!!! Nothing, nadda, no go......felt just like a t-case popping into neutral under load

I've started tearing the trans/t-case out but haven't managed to get too far with all the hours i work. I took out both driveshafts and fired the truck up and put it in drive. No movement at the t-case outputs.
I pull the inspection cover off the trans and everything looks really good, almost too good.....try "drive" again, and everything is turning there just fine, no excessive wobble or anything, still no noise whatsoever.
I take a stick (while the truck is running and in gear) and can turn the output shafts on the t-case just like everything was in neutral

I've been reading through some posts here on the 1st gen transmissions and have "heard" or better yet "read" that the convertors in these seem to be prone to failure?

So, my question is thus:
Do you guys think this is a convertor problem?

It's been mentioned on a couple of other forums that it could be input shaft, pump, or convertor, i'm just asking for more ideas here.....i can't see it being an input shaft as it wasn't under hard acceleration or anything, and i would "think" an input shaft or pump failure would make some sort of noise wether they were about to fail or are broken and trying to run it in gear?

Seriously guys, this thing makes no adnormal noises at all even now.....no humming, clanking, grinding.....NOTHING!

Idears?

 

If I read this correct your truck does not move in any gear now, forward or reverse. I would be more apt to think something broke in the transmission, like a snap ring or a drum. You will have to take it out and apart to see. If you put the truck in park can you turn the output shafts on the transfercase? That would rule out transfercase problems.

 

in park, t-case output shaft doesn't move.

Thanx for the info

 

That means the problem is between the flexplate and the output shaft of the transmission. The transmission will have to come out, if you are lucky you will see a problem with the converter, but I do not think that I would go that far and not take the transmission apart.

 

in a way, i'm thinking about swapping in an OD auto, but yet this 3-speed has done me really well up until now.

Rebuilding isn't a problem, i just hope it's nothing super major, like mainshaft or something

 

Sounds like a lot of work for OD.

 

It's not the TC. sounds like an internal tranny problem. If you do have to rebuild it see if you can get a tranny with OD instead (46RH?). You'll love the extra gear. Love it.

John

 

Thanx for the info John. Would anything else be needed to make the 46RH work, or do you think it's almost a direct bolt-in? adapters? t-case adapter maybe? I definately want to keep my gear driven 205 !

The 3-speed was great, really it was, even at 65-70mph it was good, but it felt like it could have used another gear just for "cruising" at that speed.

 

It was optional, if I recall correctly, starting in about '89 or '90. Should go right in but it might require driveshafts because it's longer. Also needs an OD lockout switch on the inside (just a simple switch mounted under the dash). That 4th gear is really important with only a 2900 RPM redline. I think you have a 3:07 rear end, but with the OD tranny you could have a 3:54 gearset for much better low end pulling and no top end loss.

My '93 was set up that way.

John

 

kool deal, i'll start the search for a 46rh then instead of a 727.

Stupid question time: does the switch for the lock-up need to be a toggle? When would i use lockup and/or have it unlocked? Sorry, convertor stupid here..........

 

HEY WMINMI, I AM GETTING READY TO INSTALL A 46rh IN MY 85 CREWCAB CONVERSION. THERE IS A STICKY IN THIS FORUM YOU NEED TO CHECK OUT BEFORE YOU GET STARTED. IT IS NOT AS SIMPLE AS JUST SLAPPING THE TRANS IN.THERE ARE A COUPLE OF MOD'S THAT NEED TO BE DONE SO CHECK OUT THE STICKY AT TOP OF THE PAGE. GOOD LUCK AUGIE DOG

 

I'd start looking for a 47RH if I was going to go through the trouble. 47RH is a lockup style trans. The 46RH, otherwise known as an A518 around here is non-lockup.

Here's the link to the one in the sticky, how to run the lockup switch is also covered. Toggle switches work fine, thats what I used.
https://www.dieseltruckresource.com/...d.php?t=114702

 

thanx, so it's the 47rh i should be scouting for, not the 46rh

lockup convertors.....let's see if i have this correct: i want the convertor to slip (not locked) when starting from a stop, but i want it locked once i get in OD?

 

Sounds like some good info is popping up. I'm not sure mine was a 46RH but I thought it was. But I'm pretty sure it was a lockup tranny. It was the stock '93 tranny with OD. The 47 might be an option but if it has more electronics watch out. Isn't that what the "E" in 47RE means? Mine had simple mechanical linkage for shifting and kickdown.

A toggle switch for the OD lockout might be better than the stock type switch. The stock one was more of an intermittant push button type switch. Every time the truck was turned off the tranny reset to "OD on" and had to have the switch pushed again to keep it in "OD off".


John

 

The lockup converter acts as a manual clutch that engages after you are up to speed and don't need the torque converter any more. So at about 45-50 MPH you will notice a slight shift and the RPM will drop a bit. Now the tranny is more efficient and making less heat. It also gives you a slightly higher gear because there is no slipping in the converter. A very cool arrangment.

The lockout switch keeps it from locking if you need a slightly lower gear. Maybe driving in the mountains, or if you want a smoother feel with no locked clutch.


John