Commando 800 can't get it into 3rd

[taubensee@sbcglobal.net 6]

My first post here. My Commando 800 won't go into 3rd gear. I drained  the transaxle and a rusty looking watery oil came out. I determined that the boot around the shifter had failed and water got into the case. Prior to this analysis I installed a new drive belt. The pulley stops when I put in the clutch and other gears work fine but trying to put it into third feelslike it hits a wall. Kinda lost as to what to do. I don't seem to have a dipstick connected to the bolt on the top of the transaxle case or is there some other way to check the level. Is the bolt on the side of the case the only way to drain the transaxle?

[ri702bill 8,327]

First off - welcome. The plug on the side is the FILL - the drain is underneath. There is no dipstick on a 4 speed. Unfortunately, the ONLY way to get a deep-dive clear inspection is to remove the Unidrive, dis-assemble it and inspect the innards. Lowell has the parts,including a repro 3rd gear. This could run into a rather expensive fix - do some searching.....

Bill

[elcamino/wheelhorse 9,311]

The drain on the trans is on the bottom of the unit behind the axles. It is hard to find based on the years of use. The side plug is where you put in fresh oil. If you remove the shifter, you may find that the rails are not aligned. Or as @ri702bill said time to pull it apart and clean and inspect..

[stevasaurus 22,757]

OK...the plug on the side is the way you can check the oil level.  The oil should be added until it starts to run out that hole.  1 1/2 to 2 qts of 90 wt oil it will take if fully drained.  The drain plug is on the bottom toward the rear of the trans...probably an Allen wrench plug.

   Oh Oh...looks like ri702bill beat me to it...but this may not be that expensive.  It sounds like a clean up issue...bearings may be good...replace all 4 seals, a new gasket, and a new boot.  Drop the trans, open it up, clean it out (get rid of any rust) replace seals.  A couple of days...maybe.  Could be under $50 and last another 50 years.  Replacing bearings can raise the price, but most are not to bad.  Not sure what trans you have, but this video will show you what you are up against.  All of the transmissions are built the same.  

 

[Jon Paulsen 290]

@stevasaurus Great video shipmate! 

 

When you do final assembly, do you use some gear oil or assembly lube on the parts? 

[taubensee@sbcglobal.net 6]

Guys,

THanks for the quick replies.

Here's what I plan to do..let me know what you think.

I'm going to drain the case and fill it with PbBlaster to see if its a rust accumulation problem. THen I'll refill with gear oil.Give it a test run.

 

If this doesn't solve it, I'll try taking the tranny apart but I don't know how to proceed on this. Is there a good instructional video that best shows this? Thanks

[oliver2-44 9,756]

Best to take it apart.

But if your set on flushing it out save some coin and fit it with diesel. Drive it around shift through all the gears many times, and repeat, repeat.

Running it will help clean some rust off the gears and shafts, but your problem is most likely in the upper shift fork and shift rail area. 

At least you will be flushing it so its cleaner at disassembly.

[Achto 27,594]

9 hours ago, Jon Paulsen said:

When you do final assembly, do you use some gear oil or assembly lube on the parts? 

 

My favorite assembly lube for engines and transmissions is Lucas oil treatment.

 

https://www.autozone.com/motor-oil-and-transmission-fluid/engine-additive-and-cleaner/p/lucas-oil-products-oil-stabilizer-32oz/169273_0_0?spps.s=2574&cmpid=LIA:US:EN:AD:NL:1000000:GEN:19502231967&&CATARGETID=120054150001287337&CADevice=c&gclid=EAIaIQobChMIlPy0-qHj_wIVchitBh0O_QZFEAQYASABEgIm8PD_BwE&gclsrc=aw.ds

[Jon Paulsen 290]

7 hours ago, oliver2-44 said:

Best to take it apart.

But if your set on flushing it out save some coin and fit it with diesel. Drive it around shift through all the gears many times, and repeat, repeat.

Running it will help clean some rust off the gears and shafts, but your problem is most likely in the upper shift fork and shift rail area. 

At least you will be flushing it so its cleaner at disassembly.

^^^ This!

 

I have not had my hands in a uni-drive gear box yet. That's TBA  But IMO anything you can put in it that will liberate the rust will also get the rust in suspension and get it into the sensitive bearing surfaces, maybe attack the seals. 

 

I can't imagine a more simple and wonderful gear box. Unless you need parts, disassemble and cleanup the guts is probably a 1 weekend job. I expect you will find something(s) that is(are) supposed to slide inhibited by solidified goo on the shaft. If that goo can be dissolved by flushing, it will go everywhere. Murphy's law says it will hang out in the bearings.  

 

@stevasaurus has given us awesome documentation or the 3 speed and 4 speed Uni's. These gearboxes are very simple, and the two versions are close enough that you will want to see both threads on rebuild.

 

@Achto I like the Lucas stuff too. You know it will dissolve into the oil and play nicely. I used Permatex red colored assemble lube last time, just because they only had a gallon jug of Lucas available at the nearby store. It worked fine too, but not as thick and sticky  

[ri702bill 8,327]

When you drain the Unidrive, to get ALL the liquid out, you need to raise the front end at least a foot to allow the oil to get over the hump on the bottom....

Raise it by the frame, NOT the front axle - that wat you can PROPERLY lube the grease fittings while waiting for it to drain completely. A half gallon of diesel fuel is all you need, works wonders.

I did a bench setup to flush last year...  worked well.

 

 

Edited June 27, 2023 by ri702bill

[stevasaurus 22,757]

Here is the instruction manual.  It shows how to take apart and put together.  Use along with my videos.

And yes, I like to coat gears with Lucas Oil Treatment when putting back together.  I flush with diesel.  It makes the tear down cleaner.  Electrolysis works if you have any rust, a wire wheel works also...sand blasting with "plastic" pellets is nice also.

 

Edited June 27, 2023 by stevasaurus

[taubensee@sbcglobal.net 6]

Steve,

 

Thanks so much for providing this....I still have 2nd gear but not enough patience to rely solely on it for my mowing. I am reminded of the old adage "if it ain't broke..." I could get the job done but slower. Nevertheless, I'll go ahead and tackle this ...hope you don't hear from me again. I have noticed some of your other videos so I should be able to rely on that info.

 

[stevasaurus 22,757]

taubensee, if you have any trouble, you can PM me and you can call me.  They are really simple inside.  The videos are all around 15 minutes to put one together.  Take good pictures as you go...if you have an issue, you can post a picture and we can usually see what is wrong.    

Remember...fear is the mind killer!!  

[Jon Paulsen 290]

Go for it @taubensee@sbcglobal.net I suspect you can nail it down in a day. Good luck with the work, fella Hoosier.

[Jon Paulsen 290]

1 hour ago, ri702bill said:

When you drain the Unidrive, to get ALL the liquid out, you need to raise the front end at least a foot to allow the oil to get over the hump on the bottom....

Raise it by the frame, NOT the front axle - that wat you can PROPERLY lube the grease fittings while waiting for it to drain completely. A half gallon of diesel fuel is all you need, works wonders.

I did a bench setup to flush last year...  worked well.

 

 

Sooooo, where's the cylinder on that thar engine? 

[8ntruck 7,011]

it is laying on its side, bolted to the frame.

Edited June 27, 2023 by 8ntruck

[ri702bill 8,327]

1 hour ago, 8ntruck said:

it is laying on its side, bolted to the frame.

Nope - that thar is a 1/2 HP E-lectric Motor I had kicking around. With the proper alility to move the Fast-On wires to reverse it to a CCW direction - like a Kohler...

[8ntruck 7,011]

But, it is the cylinder that is making the transmission go round & round.........

[ri702bill 8,327]

8 minutes ago, 8ntruck said:

But, it is the cylinder that is making the transmission go round & round.........

The cylinder is the electric motor - yellow power cord is in front of it..

[8ntruck 7,011]

And the motor is cylindrical in shape.

 

I see a visual pun here, that's all.

[taubensee@sbcglobal.net 6]

Troubleshooting....The shift lever feels like it bangs up against something when I try to shift into third. Can't get it into first either but reverse and 2nd seem smooth. So here's the question, when I get the trans open, what the heck am I looking for? How will I be able to determine what the problem is? If you've had this problem before can you give me some advice?  Thanks

[stevasaurus 22,757]

This video may help.  It is the 3 piece transmission so the shift forks are not shown (they are mounted in the casting piece).  

 

I'm guessing you have a 4 speed transmission...3 forward and 1 reverse...if so it is probably a 5053.  If you know what year and the model number, we can verify the trans.  Regardless, they all work the same. 

   The thing is, your issue would use both of the shift forks, the one closest to the front of the horse for 1st gear & reverse, and the other shaft for 2nd & 3rd.  The fact that reverse and 2nd gears push the two shafts in opposite directions rules out a broken or bent shifter.  I just don't have an idea what could be causing you issue.

   I want you to try something before you drop the transmission.  Pull you shifter out of the trans (loosen lock nut and back out the Allen Head set screw (1/8" wrench).  Have it in neutral when you pull the shifter.  Look into the shifter hole and see a square...that is each shift fork lined up.  Take a long screwdriver and move one of the shift forks into gear, the put the same shift rail into the other gear.  Repeat this with the other shift fork.  Now, did they go into the gears??  Do you have the same issues??  

   If they went into the gears, gotta be you shifter.  If you have the same issues, you need to open the trans.  Let us know what you find.    

   This picture shows both shift rails and the shift forks.  Notice the square the 2 shift forks make when in neutral.  The forks (facing away) are what hold the fork gears.  This is what you want to see after you pull out your shifter.

Edited June 29, 2023 by stevasaurus

[stevasaurus 22,757]

Chrishar just found this in his like situation.  Maybe this is your issue also.  Click on pick and scroll down to end of thread.

 

 

[squonk 41,131]

Commando 800 came with the 5085 trans.

 

This is what I use for assembly lube. doesn't run all over and is great for long term storage.

 

[taubensee@sbcglobal.net 6]

Steve,

Thanks again for your assistance. I did what you recommended, but unfortunately, still can't get into 3rd or 1st. I may try to muddle along with just 2nd and reverse but at least before proceeding with a rebuild I am wondering which seals and gasket you'd recommend I purchase. I thought it would make sense to buy all the stuff first before proceeding. I do have the 5085 trans. Can I get by with just changing the case gasket or do I need to go the whole nine yards? Got an estimate on the cost? recall the address of the place to buy is in this thread somewhere but if you'd recommend some other place please supply me with the contact info.