Bought my car last April and went through all the components that i could think of to make it safe and roadworthy. The car was restored in 1986 and the last owner used it very sparingly to say the least, so i assumed i was in the clear to just have fun in my new T and not give it another thought. Then i thought better, and now i am glad i did . I removed the rear-end to make sure it had the updated thrust washers and found that it indeed did have them, but the ring gear lash was about .030 and the wear and pitting on the ring gear was far worse than i would have imagined. Not sure if they used the original gear or if they bought a used one because it still has the Ford logo...The lesson here in my opinion is to trust nobody, but your own eyes.
Since you didn't know if there were lead babbitt thrusts inside it was a good move to check.
Though, I think you could have driven for years without problems with that ring gear - many look like that when you take them apart. Ford's method when assembling the rear axle didn't include checking the lash so it became whatever it became around 0.025" - see the service manual.
The large lash in original rear ends was likely a contributing factor to much of the wear in original ring gears, but it worked. You can reduce the play if you like but there is a risk involved if the play is too small and you're driving fast - when heat is increasing the lash may close up and it can break down?
Don't use shims between the ring gear and the carrier, friction gets too low and the ring gear bolts can be sheared off when braking. Shim behind the steel thrust plate and the housing instead.
Check the pinion bearing and the inner race on the drive shaft very carefully. They have a tendency to crack and wears more than the axle hyatts. Fun Projects makes a recommended replacement bearing since good original Hyatts are hard to find.
That would have been really expensive to fix when the ring gear failed. Good thing you inspected it John. You saved yourself a lot of money and potentially saved yourself and others from injury.
The first thing I do if I buy a Model T is to tear apart the rear axle. Invariably they are about to fail.
You could probably drive forever on that gear but, one day you might have to hit the brake hard and and that's when the teeth disappear.
Notice I said "brake" and not brakes. Think about it.
Through the beneficial advice of this great forum, I too have ended up taking all my rear ends apart only to find each one needed at least something done. First one of course had the babbit so it doesn't anymore! Other thankfully did, but needed other lesser things but it's all important to be "up to snuff" regardless.
Cripes, too cold to think and type at the same time! Mean "other thankfully DIDN'T have babbit!! They had the bronze thrust washers.
A few traditionalists insist on using the pinion bearing and sleeve. Most "upgrades" aren't, but the Fun Projects bearing really is an improvement. Any rear axle I redo is getting one.
Right with you on that Steve....great product John. No good reason to fuss with anachronisms when a bad part day can be a life changing event. Absolutely appropriate that rear end discussions are taken seriously here.
I'm using the Fun Projects pinion bearing and thought I'd replace the brass drive shaft front bushing with the newer roller bearing type. Is that an OK choice?
Phil -- It's probably OK, but unnecessary. I agree with Steve that the Fun Projects pinion bearing is a desirable upgrade, while many others are not. If you put in an original-type brass front bushing, it'll probably last only another 100 years.
You guys were certainly correct about the FP pinion bearing assembly, set mine up today and am very happy with it.
Phil, the needle bearing for the front of the drive shaft is an odd idea since the rollers are supposed to go on a hardened surface, but the driveshaft is soft. The load is very light, just the weight of the shaft, so it might work - but it's not a good design. The original babbitt or the usual replacement bronze bushing works just fine if it's getting lubed.
Indeed a bronze bushing is a better and more reliable part for the job. More complicated does not equal better.
That goes for thrust washers too. There's a roller bearing replacement for those also. I consider it a superfluous complication that adds more potential for something to fail.