98 5R55e Missing OD 1,2,4, D1,2 and R. Can drive Man1->Man2->D3->D4->OD5

[Justin_]

Hey all! Im back at it again!

A week or so ago I was up climbing 25 degree hills in the forest, trans got hot, and seemed to start to slip a bit. I took a break, let it cool, then just gently worked my way out. It worked fine after that untill...

Last night I was running up a large hill at about full throttle. Trans was in 4th gear. While I was still accelerating, the truck up shifted to 5th gear and held that for 5 or 10 seconds while I stomped on the gas. Eventually it shifted back to 4th, but instead of power it just neutraled out.

I have been here before, and happened to be right near an exit, so I coasted off the interstate and used man1+man2 to start heading home, but realized that if I turned off OD I could also use D 4, and D3 as well! A bit later I found that OD 5 works too! I think I even engaged OD3 a few times too.

So I cant just throw it in OD and drive like normal, but I can totally shift Man1->Man2->D3->D4->OD5 and that works mostly as normal.

Tonight I re-adjusted the bands for the hell of it and checked the oil pressure. I was idling around 90PSI, OD had line pressure around 120, and R had line pressure around 180.

I also checked the oil last night and again today, but it was still very clean, and there was enough in there.

Been a few thousand miles since I had it out last.



Before I start digging into things, has anybody seen this before? Not seeing that much like it.

With the clean fluid and the fact that I can get at least one version of each forward gear working and that requires engaging all of the hard parts im leaning towards the VB? Or maybe its just hope. This will be the 3rd time fkin with the trans in the last 2 years. And I just got done fixing the chains on the SOHC engine in it. Unless this sounds like a simple VB thing im leaning towards just getting a referb trans and having a mechanic install it.

Thanks

 

[Justin_]

I imagine it could also be a sprag, but it is acting SO diffrent from last time I lost a sprag

 

[JK080]

Sure sounds like a broken input sprag to me.

 

[Justin_]

Yeah, thats prolly it

I see there are lots of refurb transmissions available. Any suggestions on what ones are good/bad?

I dont really have time to do it myself this time unfortunately so I think ill need to just have somewhere. Unfortunately the only transmission shop in town is booked out for 6 weeks and wants like $4k to do it, so prolly just getting a referb from a parts shop and taking all of it to a mechanic

 

[Justin_]

Sure sounds like a broken input sprag to me.

Any idea what would cause the sprag to break just some 6k miles or so after the last one? Anything that could cause the failure that maybe I missed last time?

Ive been driving it around still and most the time its dead locked in the gears it has, but if you run it for too long it overheats, starts squealing (a bit, not horrific), and loses 5th

*has a thought*

Not long after I fixed the timing chains on the engine I went off roading. Something hard. Straight up a 25 degree hill. I was not in lo range (I know, stupid) it got hot and I thought it may have been starting to slip so I let it cool before going down and heading out. That was a few weeks before the most recent failure.

The first time the transmission failed was about a year of use (18 months in reality after spending a while recovering from a crash on said trip) after heavy off roading and rock crawling where I learned what lo gear was 1/2 way through.

I have the transmission cooler that sits in front of all the other radiators. Is that not sufficient for low speed high stress transmission use?

 

[JK080]

Its a very weak spot to begin with, after the first sprag failure there could have been wear or damage to the inner and outer races the sprag rides on and if they weren't replaced too it could cause a repeat failure.

Maybe the sprag is fine but the inner race broke off the planetary, seen this a few times.

These things can fail in a lot of different ways and most of them are due to part failure and not a heat issue. The most efficient way to run the cooler is to use the one in the radiator first then maybe a external one on the way back to the transmission.