Model T transmission thrust issue

[jimuris]

My Model T is a 1917, and it has a large brass bushing inside the brake drum. I don't have the three steel washers in there. My question is when I check for thrust, I am getting 9 on the dial indicator. The manual calls for 15, 27 thrust. But is that only for the years with the 3 steel washers.

[speedytinc]

Is the driven gear in the proper position? The book has a spec between the driven gear & the low drum gear shaft. If this clearance is too much, you would get a tighter drum pack clearance. Flush with the brake shaft is usually not enough. In my opinion, the .015-027 clearance should be the same.
Also, if the other brake drum bushing isnt in deep enough, that can effect your clearance problem. After installing this bushing, drop in the center shaft. The center shaft must touch the edge of the brake drum shaft.(No bushing hang up)

[Kerry]

Need to know more on what you have done, the back bush is the same size as the front one but with a thrust face, did you have it out? a mix of part? like the clutch plate hub or the front bush in the brake drum not being pressed in far enough.

[Dan McEachern]

Also be aware that there are two different clutch hubs- one made for the trans with the bronze thrust washer and one for the later trans that used the three steel washers. The difference between them is the distance from the thrust surface to the lock bolt. One is identified by having a Ford script forged into the hub and the other one does not. I don't currently have my notes available as to which one is which.

[RajoRacer]

To add to Dan's wisdom - the "early" clutch drums had 6 holes for the "top hat" bushing brake drum - the later clutch drum had just 2 holes.

[Mark Gregush]

Thanks Steve, I was just going to post info along those lines.

[jimuris]

Yes, I have the 6 holes. It is an all-original transmission. I have owned is since 1989. Never any issues. I just decided to tear the complete engine out.
I found two clutch finger screws worn out, I replaced them, I bought a new clutch spring. The discs are perfect. The big bushing in the brake drum is pressed all the way in. I forgot to mention I have a complete 13 tranny and it also reads 9 on the dial indicator. Both bushings in the brake drum look exactly the same. The clutch baskets are slightly different. I know you can take a little material off the baskets, but before I do anything I needed to ask for help. The car goes into gear fine. Should I put it back together. Or maybe some more investigating is necessary.

[RajoRacer]

If your "top hat" bushing is beyond serviceable limits, one can utilize the available brake drum bushing along with 2 stock thrust washers and 1 "special" thinner thrust washer available at the major vendors and you should be good - I just finished a '15 transmission last week & did that scenario.

[TrentB]

One additional point: there are two versions of the Ford script clutch disc drum. The early version has Ford script on the FRONT side of the drum and was used with the top hat brake drum bushing. The later style can be identified by having Ford script on the REAR side of the drum. This is the one used with the three steel spacer washers.

The early style drum with the Ford script on the front side is not very common, but does exist (along with a couple of other variations as Ford tried to solve the clutch disc drum/top hat bushing issue). Be sure to used the later style with the Ford script on the rear side of the drum when using the three steel washers.

Respectfully submitted,

Trent Boggess

[RajoRacer]

Appreciate the additional technical information Trent !

[Dan McEachern]

Trent- thank you for jumping in on the clutch hub issue. I almost certainly recall there being clutch hubs with NO Ford script on either side and will confirm that by going thru my hub stock. Any comments on the "no script" hubs?

So one would assume that the rear script and no script hubs are for use with the three thrust washers??

[TrentB]

Clutch disc hubs without the name Ford in script were produced before March 19, 1919. In fact Ford script was relatively rare on Model T parts before March 19, 1919 with exceptions being the top tank on brass radiators, radiator shells on black era cars, hub caps, and 1914 and later coil box switches. After March 19, Ford began putting Ford Script on virtually every part of a Model T. This was probably because it allowed dealers and owners to distinguish between genuine Ford and “spurious” parts produced by manufacturers who could not or did not maintain the same quality standards as Ford did.

Late in Model T production Ford began to phase out the use of vanadium steel, substituting type EE steel in its place. According to John Wandersee, the metallurgist at Ford, they got better service out of carbon steels, properly heat treated, than they did vanadium alloys. While vanadium is a very tough steel that is difficult to break, it does tend to crystallize and break over time due to metal fatigue induced by vibration. Two places where this frequently occurs are crankshafts and rear axle shafts. EE crankshafts are marked either on the forging or on the end of the crankshaft by the fan pulley. Type EE steel axle shafts are identified by having Ford script in the key way. By 1926 vanadium had been eliminated from the Model Ts drive train, replaced by type EE steel.

Respectfully submitted,

Trent Boggess