More transmission woes

Adam/Mill Valley CA

Adam/Mill Valley CA

Senior Member
****** for my '36 pickup, a 78- case(1939) with early gear set,behind stock babbitt-bearing motor, never abused, rebuilt about 9000 miles ago and worked perfectly, then in November broke two teeth off the reverse idler gear and two of the caged bearings failed. Rebuilt with good used caged bearings from MacVP, new cluster gear shaft and good used reverse idler gear-now after 1000 careful miles, a broken tooth on the low speed gear of the cluster shaft-all else looks fine including the caged bearings. The cluster gear was a new aftermarket item at the first rebuild(I believe from India, via MacVP). The low gear on the mainshaft really looks OK.

My question: The only issue I noticed during the rebuild was that the cluster shaft was basically a finger-pressure slip fit in the case, I assume from wear over the years. Is it possible this allowed some "monkey motion" between the cluster gears and the mainshaft gears, leading to the failure? Or any other ideas?
I'm getting entirely too good at R+R'ing this transmission!
Thanks,
Adam
 
Adam,
I read that the 1st and rev slider gear is good bur 1st gear on the cluster
has the broken tooth............check your PM's
Charlie ny
 
.005-.017" is the normal range of clearance on the cluster thrust. .025" is the wear limit. There are other clearances that need to be kept. Consult Mac VanPelt rebuilding book if you don't have one It can be a worth wile purchase!!
 
Charlie, see my PM to you
Terry, I used a new rear thrust washer with the cluster and the axial clearance looked good when I assembled it, my question was whether there was excessive play in the radial direction between the cluster and the mainshaft gear especially when under load. I do have MacVP's book (and use it), it is a terrific resource
Adam
 
I'd be suspect of the end play on the cluster gear, I do a dry fit with all related parts clean, drop the cluster in the case with the 2 thrust washers and measure the end play. Not all rear thrusts are the same thickness, new vs NOS vs NORS. I measure each thrust I have to either increase or decrease end play as required to get it into the Ford spec of .005"-.017" end play. Also, the tooth shape on the reproduction gears does not seem to have the same profile as the Ford gears, especially on the leading edges where 2 gears engage, seems to be less rounded and a bit more vertical in shape than the original Ford. Many of the aftermarket gears of the day have this issue as well, especially on the low/reverse slider and reverse idler. Check your parts closely, especially for very small chips in the low/reverse slider.
 
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