Shift pattern 1981 8LL? transmission

[coastlogger]

Another potential solution I have is I have another truck with a 15 speed mated to a Big Cam 400(the one under discussion is on a 3406)
Id imagine theyd swap,would have to swap bell housings? input shaft??Not keen on this option because of course Id be downgrading or decommissioning my (little used) picker truck with the 400.

 

[coastlogger]

Hmm not all of my post got posted. Thanks truckshop for the great pics. Think Ill have a go at a teardown. Hopefully wont have to go past mainshaft. Whats the deal on the chisel between gears in pic 5?

 

[coastlogger]

A dumb question.If its endplay thats causing 3rd gear to jump out does that mean mainshaft gears are becoming disconnected from countershaft gears (unlikely?) or the sliding clutch is disengaging. Like I said this is likely a dumb question.

 

[DMiller]

Transmissions should be direct swap regardless engines. Clutch will have a 2" input and the same configuration will be for either. May or will have to swap the clutch fork live shaft side and bell crank for the correct truck application. Will also depend on position if trans top cover will need be swapped for correct shifter location.

The chisel is holding the one countershaft to the side to allow the install of the main, these transmissions are Timed, countershaft to countershaft, get it off one tooth on either and either will not assemble or will lock up tight.

 

[92U 3406]

Be aware though if your 8LL is like my 15, you will likely destroy the countershaft bearings trying to get them out. Its been a while since I last had a transmission apart but I believe the aux section needs to come off and the upper countershaft will need to come out in order to get the mainshaft out. Input shaft can stay. If your input shaft is sealed with a lip seal, (seems to be a rare thing though but they do exist) I would change that while you're there too.

 

[coastlogger]

I think the 8ll was debunked some time ago the seller told me it was an 8ll and that prompted my original post.later figured out it is a 15 speed that will not go into 5th.if that helps? Sure appreciate the posts to date,very educational.

 

[Truck Shop]

There will be threaded dead holes in the rear section flange to use forcing screws {4" of ready rod with two nuts jammed} to remove the rear section once bolts are removed.
And you need to access how much it will cost in repairs first. It's not hard to throw 2,500 in one and happens before you know it. If the front three gear sets are pitted and the
hard surfacing is mostly gone, just find another box. You start replacing gears and main shaft and input shaft and a bearing kit plus rear synchronizer hub you will have a ton
of money and time in it. Sometimes it's best to blindfold it so it won't see what's coming and shoot in the head and go get another box. And really if you don't have a few
custom tools for working on Eaton's the job is twice as hard. And yes you will destroy the counter shaft rear bearing when removing the counter shaft.

Truck Shop

 

[92U 3406]

And really if you don't have a few custom tools for working on Eaton's the job is twice as hard.

You aren't kidding either. I did the main box on mine on the floor with nothing but a block of wood, snap ring pliers, a drift punch and a hammer. Brutal as all hell. Lost some blood from catching my hands in the gear teeth. Repeatedly.

 

[coastlogger]

Back on the case... The tranny is out. It is an RTO12515 15 speed.Cover is removed.Gears look excellent. The problems(to review) with operation are 1. no 5th(grinds a bit but no engagement). 2.Jumps out of 3rd on downhills.
So far im observing 1.the fork for engaging 5th is very worn(maybe 1/2 thru) AND the 5th sliding clutch will not go fully into the gear. The groove where the fork sits is also worn wider than other clutch grooves.Something inside gear is stopping it from sliding far enough.. I surmise the fork is worn from years of drivers trying to engage the gear.
2.3rd seems normal,sliding clutch slides in and out etc.
So Im guessing the mainshaft needs to come out,I need a sliding clutch and a fork for 5th. No idea what goes on with 3rd.
Im looking for any advice here. A recon trans is $2180. What for instance might clutches forks etc run?What else can I check to better assess things prior to disassembly.
Im not against disassembling the main section,doesnt seem too terribly complicated. Oil was good in trans,all aux functions work as they should no leaks anywhere etc.
Dumb question can one replace say the 3rd gear on mainshaft even tho itll be meshing with the old gears on countershafts?
2nd dumb question. There is a pin that goes in/out on air actuation,in the shiftbar cover.It would appear to be designed to limit shifting somehow?How does this work?Ive downloaded the eaton manual so far I havent found that feature in there.
Thx for all replies.

 

[mitch504]

pin in the shift cover drops into a notch in the rail in neutral, allows your air spool valve to shift ranges only in neutral

 

[DMiller]

Get the main out and disassembled, the issue of the gear and the not shifting will show itself pretty readily.

 

[Truck Shop]

Throw that box on a pallet and send it to me, I love working on Fuller's. If I had ten bucks for every 15 spd I've worked on.

Truck Shop

 

[mitch504]

Throw that box on a pallet and send it to me, I love working on Fuller's. If I had ten bucks for every 15 spd I've worked on.

Truck Shop

So... you're offering to fix this one for $10?
If the shipping wasn't so much, I could keep you busy at those rates!

 

[Birken Vogt]

A recon trans is $2180. .

I don't know very much about this situation in a number of places, but assuming the rebuilt is like-new good, sounds like it might be a deal to me, considering the value of your time as well. And then other problems cropping up that you don't know about yet will (presumably) be fixed.

 

[Tenwheeler]

All wear on the shift fork likely comes from a driver using the shifter for an arm rest. There are some short cuts that can be done on some transmissions like swapping the front sliding clutch with the input shaft removed. Slide the main shaft back and even swap the front drive gear. That is just a patch deal. Yours is jumping out of third also and unless it has a broken detent spring likely needs a sliding clutch and possibly gear. Call where ever you can get parts from and price 5th gear, two sliding clutches, bearing and seal kit plus a rear synchronizer. That's a fair base parts needed list. What does a manual cost and what is three days of your life worth? $2180 with a warranty is probably a better deal. Then price a reman top and consider repairing your own.

 

[92U 3406]

I think I paid about $750 for the bearing/seal kit (Eaton kit but all the bearings were Link-Belt or SKF). 2 Eaton shift forks ran me about $350 and a Quality Gear input shaft was about $200. Just to give a guy a bit of an idea on costs. Prices are in Cannuck bucks.

 

[Truck Shop]

So... you're offering to fix this one for $10?
If the shipping wasn't so much, I could keep you busy at those rates!

That was strictly a one time limited offer only good for yesterday

12515's aren't worth much anymore so the price at 2180 is about right for one that's in good working order with a bearing kit installed. A used take out 800 to 1000.
You can shoot through 1500 so fast make your head swim. I'm willing to bet the main shaft is shot it will need limiting washers and so on. To set up the main shaft
you will have to order different blocking washers to set the co-axle clearance between gears on the main shaft. Not a big deal but has to be done right, set the
clearance on the loose side of tolerance. You don't want the main shaft gears set tight on the older boxes it won't get enough lube and will gall the limiting washers.
Just some stuff to think about.

Who has this gear box for sale that your looking at?

Truck Shop

 

[coastlogger]

Got the trans apart today. Guess what the mainshaft is twisted like a pretzel right where 5th gear sits.broken spacer there (or whatever that toothed washer is called) and key broken there too.i guess that explains it all.still thinking of getting the parts and fixing it. I get Some satisfaction from doing these things.i didnt realize there were magnetic plugs in bottom. Only fine material on them.the bearing on input shaft and the bearing on rear of countershaft are not tight in housing.not sloppy they could be tightened easily by center punching.is that acceptable I wonder?loctite etc.ive made a list of parts and it's under $600 including shaft..
The recon trans is at a dealer in van bc.
Thx for replies so far.

 

[coastlogger]

're the setup if I put in the spacers that were there on the good sections would that suffice?

 

[DMiller]

If remanning your own box, get a used service manual, set the clearances loose but close to spec, the bearing/ mainshaft kits should have a selection of limiting washers included to set it right. You will be well over the $2180 when done. Did they set a core value exchange? Most will not accept a stripped down box in core. While in it may as well overhaul and replace synchro kit in back section, change all the seal rings and replace the shift interlock valve on the side of the case.