This is some generic info I got from the ARMA Build Clinic. All of the following information is directly from the mouth of seasoned ARMA mower racers who have tried and experienced the following. A lot of this specifically applies to racing and high speed, but some applies to offroad.
Stuff in [brackets] are stuff I added in.
1.) On opposing shafts in most transaxles, the gear teeth equal 50. For example, a 23 tooth sprocket will be across from a 27 tooth. With the MST series, they equal 40.
2.) Shift keys are made out of spring steel. When they get hot, they will contract and begin to skip.
3.) Transaxles dont mind being overdriven as long as they are properly ventilated and use a quality lubricant (synthetic), torque is mainly what kills them. [This mainly applies to racing, as torque is a major factor in offroading.]
3-1.) Support the shaft when overdriving. Too much tension will wear out the case.
3-2.) 700 series transaxles should have AT LEAST a 1/4" inch mount plate.
4.) Tapping the Neutral Safety Switch hole for a vent is 100% OK. It gives you more beef for the threads.
5.) When assembling transaxle gear cassettes, be sure that the "bubble" in the shims face toward the shift keys. This helps to guide the keys into the gears.
6.) DO NOT USE CARB CLEANER ON OILITE BRONZE BUSHINGS! Bronze bushings are made out of a special material called Oilite, which is oil-infused bronze. This helps to lubricate and makes your bushings last longer. Putting parts cleaner or carb cleaner on them removes the impregnated oil and they lose their lubricating quality. When cleaning, just wipe off with a dry rag.
6-1.) Some transaxles, mainly in John Deere tractors, use STEEL bushings. If you can, replace them with Bronze Oilite, as when steel rubs on steel they get hot and weld together, which will destroy your case.
7.) CASE BOLTS DO NOT NEED TORQUED. Tight + 1/4 turn is good enough. You want them to be tight, not overtight.
7-1.) Transaxle cases are cast without threads, which are made by the bolts at the factory {self-tapping bolts). Because of this, when you re-assemble you run the risk of re-tapping your holes. To prevent this, put your bolt in the hole and turn it backwards until you feel a "drop", and then tighten.
8.) To measure your belt PERFECTLY, use an old oversized belt with a cut. Wrap the belt from the front to back pulley (bypassing the clutch), but run the belt on the INSIDE OF THE ENGINE PULLEY and along the OUTSIDE OF THE TRANSAXLE PULLEY, and clamp it. Then, when you go to get a new belt, it will be the perfect size and will match your clutch motion.
Thanks to Aaron Crowl, Philip Lytle, and the other ARMA racers for the info!
Some good info here, thanks for posting. I can add a couple points, too-
On the transaxle gear tooth count thing- this is true primarily for Peerless 700 and 800 units, however I DO have one set that totalled 49. I counted repeatedly to make sure. The point of the total count is to ensure that you've come up with a matched set.
Tranny vent- Get yourself a brass fitting that is 1/4"NPT on one end, 1/4" hose barb on the other end. The pipe end WILL thread nicely into the tranny's neutral switch boss, BUT- you may have to cut grind or file a few threads off the end of the fitting. If it threads in too far, it may interfere with part of the shifter fan. BOTH 700's that I have vented, as well as MULE's 930, I have had to do this.
Carb cleaner on oilite bushings- I'd take that one step further- do not use a solvent, period. They CAN be re-impregnated, but just avoid the whole thing.
Torquing case bolts- I wasn't there for the conversation, but as a general rule, I gotta disagree. Tecumseh-peerless published torque specifications for these things, and I'm gonna stick to them.
Tranny shift washers (what are referred to as "shims" in your text)- there are TWO designs, the bubble and the bevel. Yes- the bubble (convex side) gets installed towards the keys. In the case of the bevel style, install bevelled side towards the keys. They ARE fully interchangeable. If you have both styles, you don't need to worry about having them all the same. One is just a newer style than the other.
The best way to find out is to put it in gear and see how many times you have to spin the input shaft to turn the axle once. the 915 has a unique 5th gear and revirse power flow.
the 5th gear locks the input gear to the shaft, and reverse is gear driven.
Angchor Member
Age : 67 Join date : 2014-04-14 Points : 4416 Posts : 491 Location : Index, Washington
I have been cleaning sintered bronze bushings with mineral spirits for 4 decades. (Then just covering with grease and reinstalling.)
Never had any problem with premature wear.
As I love to say- Theory and practise are two different things. You've managed to get away with it- I've gotten away with no-no's too. But when it comes to handing out advice, we tend to stick to the known conventions.
As I love to say- Theory and practise are two different things. You've managed to get away with it- I've gotten away with no-no's too. But when it comes to handing out advice, we tend to stick to the known conventions.
Understandable.
And in the spirit of that, I should add a caveat.
I would not use carb cleaner, or brake cleaner or any of the harsher chemicals on them. They WILL dry the bushing out.
And I do not let the bushing sit for even the slightest amount of time, in the mineral spirits. I use a brush and a rag, and clean the bushing as quickly as possible.
Plus, this is only for bushings that cannot be cleaned by simply wiping them off with a paper towel, and/or rag.
redlinemotorsportts Moderator
2500+ Posts
2500+ Posts!
2014 Build-Off Entrant
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Age : 27 Join date : 2013-03-18 Points : 7480 Posts : 3131 Location : raleigh nc
Bronze Zintered Bushing, you can de-grease, machine (but with clean cuts) and wash in normal stuff, WD40 or something like that. - To re-impregnate them if you machine them, you can cook them in SAE 30 oil @ 80 degrees celcius for an hour or so.
I've used them aslong as i can remember, we used them in High rev. model boat engines earlier too, funny thing back then we removed the Needle Roller Bearings and inserted Bronze Bushing, totally the opposite of what Lawn Mower Racers do to the Peerless 700's.
- But quite logicly the roller bearings can fail and do so quite easily, but a well oiled Bronze Bushing don't.
We also drilled oil drain holes and filed oil grooves in them for a more "wet" run.
They work like when they get warm and get friction they release some of that oil they've been impregnated with on normal use.
Many oils can be used to impregnate them, chosen for they're use.
Bronze Zintered Bushing are rated 18000rpm, The Needle Bearings are not. (Tho im not sure how many rpm they handle).
mudman604 Member
2015 Build-Off Entrant
2015 Build-Off Entrant
Age : 26 Join date : 2014-12-03 Points : 3778 Posts : 110 Location : hudson FL
Subject: 
February 2nd 2014, 10:48 am
