T98 And T18 Parts?

What parts interchange between a T98 and T18 transmission? Because I have a T98 with all the correct parts with the adapter plates except for the drive shafts. The only problem is it looks like it was full of water at one point and I am going to need a counter shaft and the main shaft that goes out the back of the transmission.

 

Well it's a little complicated.
One can get into Ford vs IH vs Jeep vs any other makes.

But assuming you mean Jeep T98 vs Jeep T18 then it become a little easier.
The cases and shift tower assemblies interchange prior to 1980.
Front and the rear adapter plate interchanges.

The countershafts are the same but all the gears are different except I think 1st reverse gear is the same.
I think the likely mainshaft may be slightly different but I'd have to check on that one to be sure.

 

The main shaft on mine is pitted if I can't find one then I'm going to have find a machine shop that can repair it.

 

Check with Novak Conversions for a new mainshaft if you end up needing one. You can also try Bayshore Trucks for parts. When I rebuilt my Ford T18 I got all the parts from Bayshore.

 

Well a new main shaft from Novak is $262.08

 

Mmm... a pitted main shaf should last a long time in a Jeep. Especially if that Jeep only saw a few thousand miles a year, like most hobby cars. T-98s (and T-18s) are tough, and way overbuilt for use in a Jeep.

 

I might be able to smooth it out with some emery cloth. I will have to take pictures of it.

 

Pits under the 2nd speed gear effecting the needle bearing surface would be bad.
So it just depends on where and how bad.

 

Don't reduce the diameter. Ken has more understanding of this than me... best to post up pictures of your parts.

 

The first picture is the main shaft and the other two are the cluster shaft and cluster gear. I'm going to be spending some money on this thing.

 

Yes your likely going to want some new parts.
If you rebuild with that its not going to be long term dependable.
I'll give you a better reply tomorrow after I find time to look up some part numbers

 

Way ahead of you I have a factory parts manual. I have found a new second gear. There are cluster gears in turkey but kinda pricey. The next path would be omix-ada for the cluster gear but I don't now about quality.

Mainshaft 912318
second gear 912329
cluster shaft 912351
cluster gear 912344
alternates for cluster gear
omix-ada 18890.02
154077R1
b6c-711b

 

what if I used a cluster gear with this tooth count 43-36-27-16? how would that change the ratio? The factory cluster gear has 43-36-27-17.

 

In your pic it looks like 3rd gear bearing surface of the mainshaft is messed up.
That will not matter if you always keep transmission in 3rd gear. Ha Ha Ha !
The gear must be able to spin on it's needle rollers whenever any other gear or neutral is being used.

Like I say the new mainshaft must be for either a Jeep or a IH 4WD T98.
And it cannot come from a Jeep M-715 (1-1/4 ton) nor a Ford truck.

1st, 2nd and 3rd gears can likely come from any make truck so long as it's T98 and not T18.
In your pics one can readily see the problem associated with using needle rollers under the gears.
T18 does not use needle rollers under the mainshaft gears.
The T18 design has proven to be superior concerning durability and that is the main advantage of the T18.

The countershaft that you refer to as a cluster shaft is common to all makes of both T98, T18 and T19 and so are the countershaft rollers, spacer, washers etc

The T98 countershaft gear (AKA cluster gear) is common to all makes of T98.
As you noticed the T98 countershaft gear has slightly different tooth counts as compared to a T18 countershaft gear.
As you can see from the cluster tooth count numbers that you posted the 1st gear and reverse ratios are different yet all other ratios remain unchanged.
The T98 proviides a low gear ratio of 6.399 / 1 while the T18 provides a low gear ratio of 6.32 / 1.

Actually I don't think you have any viable alternative to the standard T98 countershaft gear.
I tried it once my self.
Although it can technically be accomplished it mandates a weird mix match of parts in order to accomplish the installation.
The strange mix match becomes mandatory because the reverse gear and 1st reverse sliding gear tooth counts also differ between T98 and T18's.
I have never seen the strange mix match in use and would never recommend attempting it unless one just happened to have all the appropriate associated parts handy including associated 1st reverse sliding gear,reverse idler gear, reverse idler shaft reverse idler bearings etc.

While I'm at it I'll mention yet another major concern when interchanging of various T98 and T18 compomnents.
The maindrive gear consider that there obviously exist different stickout lengths.
But beyond that we must become concerned with fitting the mainshaft pilot into the maindrive.
The T98 maindrive to mainshaft pilots will not interchange with T18 diameters.

All Huge 1st / Reverse bronze blocking rings will interchange between various makes of both T98 and T18.
But the smaller 2nd, 3rd and 4th gear blocking rings is a different concern.
For them there were basically 2 sizes manufactured. Small or large cone face.
Jeep always used the smaller cone face 2nd, 3rd and 4th gear blocking rings in both T98 and T18.
Ford always used the larger cone face 2nd, 3rd and 4th gear blocking rings.

Though its not a huge concern my insight leads to to believe that Ford had the better idea.
The larger diameter cone clutches provide more surface contact area .
That basically implies less chance for any gear grinding when changing 2nd through 4th gears.
Or means that a friction modified transmission lubricant could possibly be used.

This is all rather important to note because it also mandates having different size cone clutch surfaces on the various maindrive shafts plus the 2nd and 3rd speed gear cones.

Got that ?

Concerning the NOS mainshaft .....is that from "NOS4JEEPS" out of Turkey ?
And please never consider Ommix Adda....

 

I think the shaft could be flame sprayed. I don't know if they could do the inside if a gear.
Flame Spray Metal Coating Services near Denver, CO | Kendo Inc

 

Well I found a new second gear, cluster shaft and cluster gear. So I'm down to finding the a new main shaft. The T98 was also used in International Scouts right or was that the T18?

 

Glenn......It's been a long while but I had great success buying actual NOS from NOS4JEEPS.
Problem I see is that most of his genuine NOS has already been sold off.
This simply means one really needs to know exactly what they are buying.

Just a couple weeks ago I saw a complete NOS Jeep T98 on eBay for only $350.
Problem is it was the M-715 version.
So the maindrive and mainshaft and front bearing cap are not useful to F-134 CJ's.

 

I paid alittle bit more than $350 but I got the right parts with the adapter plates, tcase shift levers, and cross member. All I need are the drive shafts and the floor pan. Bit there is a rebuilt one for $2500 all you get is the transmission nothing else.

 

Don't buy that Ford 2nd speed gear as currently seen on eBay.
The Ford T98 gear cones are probably too large for Jeep applications.