Vintage T98, D18 and Overdrive

I'm sure they could have made a one-piece bell for the CJ application if they decided to. The pictured crazy long bell went away with the change from to the AMC 360 in '71. Instead, they used a regular T-15 CJ style bell and a 5" long adapter. This continued to the end of manual transmissions in the SJ platform - my J20 has a big spacer too.

Better Wagoneer/J-truck drivetrain info here: http://www.ifsja.org/tech/figures/db.html

This says '69-71. The claim is that the '71 models with the 350 were just Jeep running out the inventory. Supposedly you could special order with the 350 in '71, even though the official factory offering was then the 304 or the 360.

 

OK,
I cracked it apart tonight for investigation. Glad I didn't wait...



images:
pulled the OD off, but didn't read well, had to read HERM's uninstall and it made much more sense.



inside the top cover:



FYI: I put a tape measure at the base of the bearing retainer. Looks darn near 10" to the end of the shaft.



Yum, this just looks outstanding:



OK, it looks like this bearing retainer has seen some modification.



Looking inside the transfer: the gears are sharp no galling.



Here's the inside of the adapter. Just wanted a positional shot for GP.


Low gear looks galled a little around the leading edge (I assume): Still doesn't look bad.



Part number of the small adapter between the BOP Bell adapter and the front of the t18.


Part tag from the Transfer Case:


I think the crack I see here on the right is the old gasket material...
I'll be double checking now...



this one is hard to read, it's the cast and part number off the BOP bell adapter:
I think it reads:
1 8 2
941185
No 3

 

Except for some water in the oil, it looks good to me. Some rounding on the 1st gear teeth is typical and not important.

992667 is the factory plate adapter they used on all the 258-T18 Jeeps in the early-mid '70s, both CJs and FSJs. This is a 1970-ish Jeep PN. It's definitely Jeep.

Bearing retainer looks unmodified to me.

Maybe Jim can do something with the transfer case tag, or the other adapter number. 941185 is also 100% Jeep, and is earlier, like late '50s / early-mid 60s.

 

947383 = CJ5 V6 3.73 T14 original application for the D18.
992667 = factory adapter for 4 speed used with V6 1 piece bellhousing
This adapter is used in other applications as Tim pointed out.

941185 = V6 adapter used with 2 piece bellhousing, 3 speed or 4 speed transmission

 

Apparently this was somewhat cobbled together.
The shift tower shows set screws into the shift rails and that definately indicates pre 1969 vintage.
Those early shift towers were only used on T98's.
One example... 1967 and 1968 M-715's would all use set screws for attaching the shift rails.

All T18 shift towers should all have roll pins for attaching the shift rails.

The 992667 part number becomes valid sometime in late 1970 or 1971.

Looks like a 17 tooth maindrive gear (MDG) meaning that it's either 6.32 or 6.39 ratio. (wide ratio)
Several ways to determine T98 from T18 guts without dissassmbly.

T18 gears.......VERSES.........T98 gears
40 tooth.......LOW GEAR........43 tooth
16 tooth.....REAR CS GEAR.....17 tooth
20 tooth....REV IDLER GEAR....21 tooth

If measured from transmission the M-715 MDG stickout length is 9-1/2".
OAL MDG length is 2-5/8" longer or 12-1/8" OAL for M-715 MDG.

This could possibly be a mix of M-715 guts and shift tower mated to the front adapter plus T18 case that were taken from narrow ratio 1969-1971 CJ-5.
In essence an early CJ T18 was modified to become 6.39 wide ratio.

 

Wow. Encyclopedia jeep. This is great stuff.
End play seems a bit much in the transmission, may be a 1/8" jiggle. Concerning is that while it was apart I undid the inner nut to the OD with may be 20lbs or so. Definitely was not even farmer tight. I see really no major wear yet.
My daughter (6) walked in the garage this morning and asked me what stinks so bad. (Gear oil).


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Added to previous post.

 

Wild. If that's what it is, I expect the original builder could never have figured out the combination unless he had all these parts on-hand. I would expect he would have had to use the T18 main shaft, because the T98 from a M715 has a divorced transfer case. Are they compatible?

 

Ken and all:

I will confirm later today by counting teeth now that it's all open. Thanks!

Using Novak's Calculator:
if it's 6.39 that's a 77:1 CL with my 4.88s
if it's 6.32 that's a 76:1

I'm happy I think either way: this stuff appears bullet proof if I can put everything back to spec and get it back in the jeep.

Johnny Cash is playing in my garage... it's a 66,67,68,69...71... but I'll hope to unwind it one piece at a time.

Question for folks:
How do I get the nuts off the output shafts (yoke mounts) now that this thing is partially dis-assembled: it seems shall I say: "Challenging?" I've thought about a pipe wrench on the collar of the yoke while I twist on the nut but that seems lacking in finesse and likely to break something (including knuckles). I'm short on air/electric impacts...

Anyone have an opinion on how to clean out these cases (degrease, pressure wash, WD40, then re-lube)?

going to go buy some WD40 anyway. Haven't had any of that in years.

thanks!

 

You going to take it completely apart? Buy a gallon of paint thinner and scrub the case and all the parts with solvent. Only the cast parts should need a lot of scrubbing. Once all the oil is off, you can scrub again with Dawn and a stiff brush to get the slightly oily residue off. Be sure to dry everything thoroughly with some rags or shop towels. Blow out any holes with air, if you have it.

The surface rust spots on the gears should come off with something mild like fine steel wool or a worn-out Scotch Bright, or even a fine wire brush. You may have dark spots where the spots were - I'd probably leave them alone rather than try to polish the machined surfaces.

When you assemble, keep it dry and the machined surfaces should not rust. You can coat the internal parts with gear oil as you put it back together. Most would hold the roller bearings in place with lots of Vaseline - that will dissolve right away in the gear oil.

There may be a fancy assembly lube for manual transmissions. I expect that would be fine too.

To remove the nuts, put the transmission in two gears at once and it won't turn. Then you'll have to hold the case somehow.

 

Dane,

I would disassemble the complete transmission & clean & inspect it............then there's no questions on bearings or syncros. I use a piece of 2 inch square tubing that I welded a couple of pieces of flat bar too as shown in the picture to hold the yoke. I normally also use a 3/4" air gun on the nut............but if you had a 3/4" drive set and a short piece of pipe with it you might be able to get it loose........someone would have to hold the socket on the nut tightly as the nut is shallow and you don't want to bug it up.........That's a good repair manual in the picture.........says for a T-18 but should cover 90% of your tranny.......also I like the Smart Blend Synthetic grease............put it in the freezer the night before sticks like glue to the bearings. Both available on E-Bay

 

Tarry,
Thanks. I bought that manual for another t18. Good to know. I'll check on the goop to freeze.
Might have to visit cardboard freight for a disposable air impact.


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Oh, I like your holder. Rummaging thru metal heap.


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Appears that a tooth count of low is 43. Last cog in line is 21. Smells like t98.


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Yeah, Tim is Right-on about that.
The needed T98 mainshaft does not come on an M-715 because it's a divorced style output.
The T18 and T98 mainshafts are not normally compatable.
I certainly would not recommend interchanging T98 and T18 gears and mainshafts.
I do believe however that they could be swapped under some very complex conditions using a particular combination of intermixed gears and shafts.
The interchanged gears and shafts can mesh sufficiently well yet they may not mesh precisely as originally intended.
This really implies that full tooth contact may be compromised on the straight cut gears.
The questionable gear meshing would involve the rearmost gear on the countershaft gear cluster to the reverse idler and also the low slider gear.
Those are all straight cut gears with varying tooth counts.

Not to confuse issues further but many T98's were built for industrial applications like the Timberjack log skidders etc.
So the exact components used for this modified combination T98/18 is a really a guess without posatively identifying certain parts.

Dane, double check your MDG dimensions.
The M-715 MDG stickout must be almost exactly 9-1/2" from the front of the transmission.
Anything other than 9-1/2" suggests a different MDG.

 

I just started disassembly last night. I pulled everything apart that is exterior the components in the case. When it warms up a little today (34 now) I'll go turn on the shop heater and take some more pictures.

What I disassembled so far has been scrubbed with spirits and a wire brush, including nuts, washers, bolts.

Part numbers are becoming visible as crud is washed away. All so far appear to have the jeep part numbering.

Before I start on the cluster and components I will make some scratch lines or something to indicate positional alignment.

Edited:
Today I didn't get far: I have the large input / output snap rings removed and that's as far in as I've gone at this point. I used a scratch tool to scratch relative positions on gear teeth (and syncro teeth). Hoping I can scratch an 'f' on all the parts where they face the input shaft.

Some pictures, but not enough to post.

Verified MDG shaft stickout at 10" from face of transmission.

Also working on the D-18 and removing the shaft nut for the yoke mount took me some doing: nothing like a strong air impact... this was a time sink as I had to find a thin-walled 1 1/8" socket to fit it (grumble). I was just seconds from chucking my socket into the drill press and hitting it with a file to thin down the sides.

Anyway, I'll tackle the T-18 more tomorrow: reading the manual again tonight.

Lots and lots and lots of grease / goop / 90wt to remove. This is the driving factor as this smell.

 

OK,

Man, I wish there were more hours in the day for this, as it's much better, more fun, etc. than sitting at work using my head to mash a keyboard to solve a myriad of programming and IT woes...

Transfer case is apart completely.
Gears are cleaned.
chased holes with a tap to clean out the greasy goop / RTV / shellac.

Starting to tape/sandblast some parts. Painted those that were finished (PITA to tape off mating surfaces). Once paint cures, I'll probably use a little bar-keepers-friend and a scotchbrite to shine up the mating surfaces. May be - since they'll get a coating of RTV or something similar based on their need when bolted back in place it might be moot.

Have a twin-stick kit from R&P. Looking forward to installing that.
Have intermediate shaft, bearings and seals from Novak.

Picts to come of the old intermediate where it was etched, and oddly, the intermediate shaft bearings were wearing in almost a 'triangle' pattern rather than evenly around the shaft (like the shaft was off-center-canted or something).


---- Transmission ----
Found a used over-up knob. Seem hard to come by in 'vintage' edition (new, aluminum, and all sorts of Chinese stuff is out there).

chased holes with a tap to clean out the greasy goop / RTV / shellac.

Sent a note to Novak today to see if they have the rebuild parts for this oddity (bearings, syncros, seals, etc.).

While I like the idea of the over-and-up transmission in my '69, I have a good later model from the 80's too that's over and down and supplies a backup-light I can use if I go that way. (anyone else collecting parts, then another deal lands which gives dupes you don't need necessarily?)

Mildly considering parting this transmission out rather than rebuilding if it seems too much of an abomination. All the gears look good with the exception of the very mild rounding from someone grinding first to get it in gear.

I'm fighting the snap ring on the front of the MDG still. What a pain. Just when I think I have it, nope, knuckles busted or it slips around and I lose my bite on it or something irritating. I have to walk away or risk filling the swear jar with a stack of $10 bills.

--------------

I've been trying to read on bearings, replacements, cross-references, etc. to see if there's better input/output shaft bearings than the set that comes (Federal 1308cg output, the front on the MDG looks same but I can't confirm yet). Seems we should have more efficient bearings/races now than these (and that would seal the oil in much better and supply the same or better load distribution at same RPM range).

Hope to take some pictures tonight. X-ing fingers that I finally get the danged snap ring loose tonight.

considering chasing all the threads on all the bolts with a die to clean/straiten for when it goes back together, I've done a few and it's, well, mind-numbing...

d

 

Over and down is better functionally. With over and up, most clip reverse occasionally on a 2-3 shift... especially if the shift top reverse spring is broken, and/or you aren't careful on every shift.

 

Your front bearing retainer has been brazed back together. If you re-use it, chuck it up in a lathe and make sure it's true. If I was doing this, I'd eliminate the adapter, install a short input shaft and different retainer, and bolt this up to a Ford to Buick adapter bellhousing, but that's just my opinion. That's a lot of adapter for a CJ. My 55 CJ has a T98/D18/Warn OD setup in it. It's bolted directly to the F-head bellhousing with no adapters. The granny low is so sweet for idling up hills in low range. I have another T98/D18 setup sitting in a roller M38A1 that will be used in a future project.

 

Weekends are not long enough.

With the exception of the front bearing retainer; the Dana 18 parts have been wire-wheeled, media blasted, primed and sprayed with rattle can 'high-temp' black. I debated gray, but black won out (available on shelf). I have to come back and scotchbrite the mating surfaces now.

While these parts cure for the next few days (garage is ~50 on average), I'm working on a simple tool design to pull the front bearing from the MDG in the T-18. I have a lot of pullers, but none with a 10" reach. Such is life... I may call it 'my big 10 inch' as an homage to Aerosmith, I'm sure that is what they were talking about: Car parts and tools...

I found a picture of the original Jeep puller: Interesting box shaped affair with a sort of clam-shaped nabber for the bearing groove. I think I can make a close working approximation with some flat stock, some 16ga sheet a couple of half-inch nuts, a bit of half-in all thread and two 1/4" bolts/nuts to hold the radial flex part and keep the clam-end-nabber in the groove.

Got to check with a buddy that has a lathe to see if we can chuck it up to check it's 'trueness'; I think it's ok, as there's no wear marks that would indicate alarm, but while it's out I'll check it. Secondly, I'm thinking while it's chucked, it might be a good time to etch a groove for a large off-the-shelf O-Ring in the base if room-to-groove presents itself.

Pictures to come this evening. Ooooo la la.

d