Excessive Mainshaft 3rd Gear Side Play

Andrews 4-speed Third Gear

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Mongrel505558
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Excessive Mainshaft 3rd Gear Side Play

#1

Post by Mongrel505558 »

I replaced the mainshaft 3rd gear in an early '76 4-speed I've been running in my mutt panhead with an Andrews 3rd gear. I installed it with a new thrust washer and retaining ring on the mainshaft. The retaining ring is seated squarely in its mainshaft groove. With the transmission fully assembled this gear has about .021" side-to-side play. Manual calls for .000-.017" here, and when I shift into 3rd (on the bench) I get a rumble when I turn the mainshaft by hand. I don't see any interferences. The mainshaft is a sweet fit in the main drive gear bushing and is installed with a new SKF ball bearing. I ordered this gear with some other parts and when the box came the gear was missing, so I called the vendor. They checked and verified they had one extra gear on hand that was unaccounted for and shipped it to me free of charge. On the box there is a sticky note that has my name hand-written an the number 56051-59. The correct H-D part number is 35306-59 for the non-bushed 59-and-up 3rd gear. I tried to reference 56051-59 and came up with no matches. However; when I entered the Andrews PN DS199415 it comes up with the right description (3rd gear mainshaft 59-86). The 3rd gear it's replacing didn't have this problem, but it was chipped, pitted and rusted. Unfortunately I no longer have it do compare the new gear with - I used it on a lamp I made from old parts for a charity raffle. Anyone encounter something like this before?
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Re: Excessive Mainshaft 3rd Gear Side Play

#2

Post by RUBONE »

Are you sure it is the correct number of teeth? Andrews makes a stock replacement and a close ratio third. If the mess is wrong it could be the rumble.
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Re: Excessive Mainshaft 3rd Gear Side Play

#3

Post by nifty »

I'm with Rubone on newly introduced rumble being a meshing problem.
No burrs? maybe new teeth wider and getting interference from previously untouched portion of layshaft gear teeth?
Damaged layshaft teeth which had "run-in" with old mainshaft gear?
Did you take out an Andrews close MS 3rd? and replace it with a new Andrews close MS 3rd?
The Andrews MS 3rd must be run against its corresponding Andrews countershaft 3rd because gears have been specially cut (they fiddle the cutting to get special ratios, old time belief was that for a given tooth type, the teeth sum of every pair of meshing gears had to be equal for all ratios, this thinking limited ratios, hence the "fiddle" was invented. Norton started doing it way way back.

Re 3rd end float, there are multiple thicknesses of thrust washer thickness, theoretically in .005” increments, .058; .063”; .068; .073; .078” & .083”.
However, these days the actual washers usually measure 2 to 3 thou under what they are supposed to and I have also had them wrongly packaged .i.e 15 thou bigger than I wanted. In other words the usual crap shoot.
zero to .017" is an old spec (and you definitely want some end float)
Later spec is .003" - .010"
I aim for .010", the end float is how the oil gets in.

Nifty
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Re: Excessive Mainshaft 3rd Gear Side Play

#4

Post by nifty »

Ran out of edit time

Andrews DS199415 part number is for close ratio mainshaft 3rd
Seems like you wanted std ratio which is AP-206220

Nifty
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Re: Excessive Mainshaft 3rd Gear Side Play

#5

Post by Mongrel505558 »

Thanks, guys

I believe you nailed it. I'll go count the teeth later today, but if DS199415 is for close ratio 3rd, then that's what I have. Unfortunately, that's not what I wanted. The countershaft, and the rest of the box, is early 77 FX. That probably explains the excessive backlash in third gear. Now I get to fiddle with that retaining ring yet again. I'm glad I bought 6 of them with my last order. Seemed like a good thing to have spares of. Any suggestions for a source of varying thickness thrust washers?
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Re: Excessive Mainshaft 3rd Gear Side Play

#6

Post by nifty »

Last time I checked Tedd, J&P etc listed some, but Flatland had the full range of 3rd gear thrust washers.

90deg scriber or Roodogs re-ground spoke for easier removal. When I have nothing else to do. I'm going to grind a spoke and thread a long handle on, I reckon manipulating from a distance will get my paw out of way so I can see retainer better.
Nifty
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Re: Excessive Mainshaft 3rd Gear Side Play

#7

Post by Mongrel505558 »

nifty wrote: Mon Sep 06, 2021 11:57 am Last time I checked Tedd, J&P etc listed some, but Flatland had the full range of 3rd gear thrust washers.

90deg scriber or Roodogs re-ground spoke for easier removal. When I have nothing else to do. I'm going to grind a spoke and thread a long handle on, I reckon manipulating from a distance will get my paw out of way so I can see retainer better.
Nifty
I've gotten pretty good at it using a 90 degree dental pick and a small flat blade screwdriver. I can hook the ring with the pick and pull it out of the groove and walk it off with the screwdriver. I just keep turning the mainshaft until I get the ring completely out of the groove and up on the splines. It's pretty easy from there. This is my spare "practice" transmission that I'm using to teach myself the art of rebuilding 4-speeds, since I have two bikes that run them.
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Re: Excessive Mainshaft 3rd Gear Side Play

#8

Post by Robert Luland »

How Not To Drive Your Self Nuts Setting Up Mainshaft Third Gear In A BT Four Speed Box.
A dirty white paper By Bob Luland

A few words before we get into this. First off keep in mind this is dinosaur technology, so don’t lose sight of that. You are not working on a Ferrari with a constant mesh transmission at Le Mans. One of the big problems you are going to run into with third gear is the end play, even using the thickest thrust washer on the market. I have never been able to get the end play where the manual says it suppose to be. Could ya put two thrust washers in, why not? That’s what a surface grinder was made for. Do not adjust third gear in the box. This is the part that will drive ya nuts. Instead, go cut yourself a piece of 1” pipe or buy a nipple at a Home puke and cut it to 5/8”long. This piece of pipe will replace the ball bearing 9020 on the mainshaft.
1. Slide 1/2nd gear on to the shaft. If you have a 58 and down 3rd gear. Make sure the bushing has been replaced if you’re doing a total rebuild.
2. Now slide the piece of pipe ya cut on to the shaft in place of the ball bearing. Screw the nut on and snug it up.
3. Put the ball bearing end of the shaft in a vice with soft jaws.
4. Grab third gear and slide it on along with the thrust washer and retainer clip. From the sprocket side. Doing the job this way keeps the clip in the open. Even still. Before ya start. Go on Fleese-bay and buy yourself some cheap dental picks. The kind they really use in Calcutta. The picks make taking the retain clip on and off a breeze. Use the same clip until ya get everything set up and then discard it. Always use new clips upon assembly. Set your end play and disassemble everything and you’re good to go with the rest of your build. With this system you don’t get to say $%*!^#$@^@ even once. Bob L
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Re: Excessive Mainshaft 3rd Gear Side Play

#9

Post by Mongrel505558 »

Robert Luland wrote: Sun Sep 19, 2021 1:59 pm How Not To Drive Your Self Nuts Setting Up Mainshaft Third Gear In A BT Four Speed Box.
A dirty white paper By Bob Luland

A few words before we get into this. First off keep in mind this is dinosaur technology, so don’t lose sight of that. You are not working on a Ferrari with a constant mesh transmission at Le Mans. One of the big problems you are going to run into with third gear is the end play, even using the thickest thrust washer on the market. I have never been able to get the end play where the manual says it suppose to be. Could ya put two thrust washers in, why not? That’s what a surface grinder was made for. Do not adjust third gear in the box. This is the part that will drive ya nuts. Instead, go cut yourself a piece of 1” pipe or buy a nipple at a Home puke and cut it to 5/8”long. This piece of pipe will replace the ball bearing 9020 on the mainshaft.
1. Slide 1/2nd gear on to the shaft. If you have a 58 and down 3rd gear. Make sure the bushing has been replaced if you’re doing a total rebuild.
2. Now slide the piece of pipe ya cut on to the shaft in place of the ball bearing. Screw the nut on and snug it up.
3. Put the ball bearing end of the shaft in a vice with soft jaws.
4. Grab third gear and slide it on along with the thrust washer and retainer clip. From the sprocket side. Doing the job this way keeps the clip in the open. Even still. Before ya start. Go on Fleese-bay and buy yourself some cheap dental picks. The kind they really use in Calcutta. The picks make taking the retain clip on and off a breeze. Use the same clip until ya get everything set up and then discard it. Always use new clips upon assembly. Set your end play and disassemble everything and you’re good to go with the rest of your build. With this system you don’t get to say $%*!^#$@^@ even once. Bob L
Good advice. I have a "sacrificial" ball bearing I can use to set it up. I'm not going to go nuts trying to get it dead on. I measured the new thrust washer I used during assembly and it was thinner than another new thrust washer I have. I don't have the numbers in front of me. I wrote them down in a book I keep in my "shop" downstairs.
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Re: Excessive Mainshaft 3rd Gear Side Play

#10

Post by nifty »

I thought everyone set 3rd gear end-float in vise. :D
Nifty
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