Attached is a photo of my pinion meshed with the ring gear. Is the relationship between gears OK? I put some prussion blue on one ring gear tooth and it is centered on the pinion tooth surface.
My dial indicator isn't like the one shown in the rear axle rebuild book. can I measure gear clearance off the pinion?
Too me it looks like the pinion is too deep?
No gaskets on pinion housing but I would need a bunch to take that out. The drive shaft front bushing is good - no measurable end play in the drive shaft. Pinion is torqued to 70 ft-lbs and is flush with the pinion sleeve.
The thing you need to check if your pinion is riding that deep to get correct lash, is that the teeth don't hit the ends of the bolts that hold the ring gear.
Jim.f that was my assembly, I would be looking to get full engagement of the gear teeth. If your tailshaft assembly is all good, them I would space it forward to get the required depth of mesh. This could well mean the diff centre will need to be shifted to get the lash correct. This can be done with shims, either behind the ring gear or the thrust washer discs.
Hope this helps.
Allan from down under.
Kerry-This the way it went together with no gaskets or attempts to set the gear clearance.
Allan-do you mean by full engagement that the pinion is not as deep?
Jim if your pinion and ring gear teeth show full contact with Prussian blue as you indicate, you're better off leaving things as they are.
In a perfect world, you measure run out by reference to the movement of the ring gear not the pinion, because the pinion revolves in a tight circle and the readings will reflect that. But you won't be damned in hell by measuring pinion tooth movement. Make sure one pinion tooth is sitting in the center of the ring tooth valley before you rock it back and forth.
If you assembled your rear end without shims, you may find 25 thou gear lash. For some that is excessive, but that's what Ford used according to one source. I strive for about 15 thou lash.
Jim, Looks like you are using used gears, don't worry about visual depth of pinion to ring gear. You can use the dial indicator to check backlash. As long as there is little backlash and the gears aren't bottoming out you should be good to go! A old trick is to run a piece of paper through the gears. If it makes a tight fold without tearing the paper the clearance should be good to go.
One other thing, if you are using Henry gearing, 3.63 to 1, the bolts should be behind a ring tooth, so no concern about hitting them with the pinion. As Kerry observes, its a different story if you are running different gearing or are using some of the older repro ring gears that were not made correctly.
Ring gear is Ford so bolts are positioned correctly.
Jim, Yes, the pinion looks too deep. But if you have full engagement of the ring gear teeth across their full width, then there is no need to alter things, as others have suggested. If not, I would shuffle things around until you get full width engagement. That pinion gear does a lot of hard work, especially under severe braking. Not having full width engagement loads it even more.
I have two broken Ford script pinion gears. One was split under heavy breaking, the other lost a tooth. I try to give them the best chance of survival if I can.
Hope this helps.
Allan from down under
Here's a part of the Rear Axle Rebuilding Clinic information that my daughter and I presented at the Sunflower State Crankers Chapter MTFCA Mid-Winter Model T Clinic in January 2013. This was really a project which the Flatland T's of Kansas Chapter helped put together. We worked all year long as a group on it. One of the things we ended up with was a "cut-away" rear axle that was donated to the McPherson College Auto Restoration program as an instruction aid. Here's the section of the write-up that might help you.
The driveshaft is perhaps the most misunderstood piece of the whole rear end assembly. What is really important is to obtain the fit of the driveshaft assembly so the gears mesh as they should. The base point of the driveshaft assembly is the tail end of the driveshaft housing. That flat surface is the starting point from which all other distances are measured. From it, the remainder of the driveshaft is built. The driveshaft ball bearing assembly fits up tight against the end of the driveshaft housing. The original Model T Parts books do not show a gasket in this location. If a gasket was used, it would need to be under the driveshaft ball bearing assembly in order for the thrust bearing to be held tight and “in position”. This could be done but it wouldn’t seem like the way Ford would have intended it. If it was not under the thrust bearing, there would be a gap between the thrust bearing and tail end of the driveshaft. This would allow the bearing to move back and forth which is not a good thing. The next point is the inner bearing sleeve. If it is not the proper length, or in the proper position fore to aft, it would be a problem. This appears to be set by the back side of the pinion gear and the fact the other end of it is running against the driveshaft ball bearing assembly. This inner sleeve should be positioned right at the back side of the pinion with no gap.
When a new driveshaft housing front bushing is installed, it needs to be faced off. Assemble up the tail end of the driveshaft (thrust bearing, inner sleeve, roller bearing, pinion, spool, thrust washer (early style only) and pinion gear with nut) and slide the driveshaft up into the driveshaft housing with the new thrust in place. Install the u-joint and look through the pin hole. That will tell you about how much needs to be faced off of the brass thrust surface beneath the u-joint. This is what sets the end play of the assembled driveshaft. Take light cuts and check often. It might be that it will take a dozen or more times before it is sufficiently faced off. The book says 0.002 to 0.005” clearance. This is rather hard to measure owing to the fact it is buried inside the u-joint housing. What you are really looking for is a nice running fit that does not bind. As soon as you obtain that, quit facing off the front of the bushing. To backtrack a little, on the early enclosed bolt driveshaft bearing spools, there is a flat washer between the roller bearing and the driveshaft thrust bearing. The inner sleeve is a press fit on the driveshaft. It is best to use some anti-seize on the sleeve when installing it.
A little more about the driveshaft thrust bearing...
The thrust bearing had two basic styles. The early one was a cup type and then later (when the exposed bolt spool came in about 1920) there was a ball race with thrust plates on either side of it. The wear on these tends to be where the inner sleeve rode on the face of the thrust bearing. The later style thrust bearings can just be turned end for end to obtain a new surface for the inner sleeve to ride. The early ones don’t have that option. The catalogs show this thrust bearing was the same for all years but we’re not sure this is the case. It was discovered that there is a difference in the thickness of these thrust bearing plates from early to late style. The later ones were a little thicker. When the unit is assembled, it causes the pinion gear to be pushed towards axle.
Hope this helps.