OutdoorKing Repair Forum Forums Repairs and Maintenance Questions On Ride On Mowers Questions On Ride On Mowers Frames mtd 155-hydro

Hi guys,today i had a phone call from a local contractor (we share the work)that his mtd rear catcher ride on is for sale with a non working hydro diff.every thing else is working and always serviced-as he is local i know the condition of the mower so i went around with the trailer and picked it up for $500.00.
the model is MTD-155h-hydro
13BA518N670
BJ073L10020
15.5HP intec briggs
model-286H77
type-0186E1
code-030804ZE

As in the above pics using the 5th icon (easy) i have looked back in previous posts as to why and how the hydro diff does not function.from what i have read the oil would be normal diff oil 90 grade and is there a breakdown diagrahm of the diff so i can repair it.thanks...ken

You are ahead of me Ken, I'm used to the final drive being separate from the hydro transmission. Hydraulics use hydraulic fluid, which has always been a light oil in my experience so far - usually a form of automotive auto trans fluid. I'd be surprised if you should use 90 grade diff oil (which is just about always hypoid oil, or EP90) in a hydraulic pump - I would expect that to end very badly indeed. I'm used to there being a hydraulic circuit, and a pool of oil in the final drive, but they are quite separate. I suggest you look into this carefully before you put 90 grade oil in a hydraulic circuit. Incidentally built-in tractor hydraulics often use engine oil, which is slightly heavier than ATF, but I suspect that was partly because the designers knew very well that the farmers were going to put engine oil in the system whatever they recommended, so they designed the system to cope.

thanks grumpy,i was so excited about my buy that i mixed up my oils,they say to use 20 grade oil so would that be the same as auto trans fluid?.i am going to un-do the fill plug and check the fluid level and take out a sample with a sarynge/rubber tube.i have safely jacked up the rear of the mower and will take pics as i go,even if i hafe to remove the rear diff and dismantel it for diagnostics .if the diff is broken internally i cant break it anmore but will be interesting for me and others to see whats going on...ken

Ken, if you can take some pics and post them along with your notes and comments - maybe different threads for the hydro and the rear axle - it will be a big help to other ride-on owners, as you said.

Auto trans fluid has a lower "base stock" viscosity than SAE20, but it has lots of viscosity improver to make up for it. I strongly recommend that you use what the hydro manufacturer specifies - those things are awfully expensive and fairly delicate. Make sure you clean around the filler before you take off the lid, and generally keep things seriously clean. Is there a procedure for changing the hydro trans fluid? It probably needs it.

You'll need to take a careful look at the drive belt of course, in case it is worn.

Hi grumpy,i thought i might continue this thread so people could relate the hydro drive with the mower in previouse pics.
i checked the oil level after a full clean-down of grass etc-oil level full.on the back of the mower is a small rod where you can pull it out to lock the diff (both wheels drive)and push it in for single wheel drive.on the single wheel drive and starting the engine the left wheel would turn forward and reverse but if i held the wheel it would stop so i went to the right wheel for the same task.on moving the wheel i noticed the outer bearing had collapsed hence the whole axle shaft came out some distance.i then removed the whole rear drive ass for further repair,here are some pics...ken

Some more pics

So grumpy,i have been on the mtd site and the eaton hydro diff site with no luck on a schematic break down on the diff before i start to pull it down,can you or bruce help me out.i can just replace the outer bearing but the internal spider gears might have dropped down or out of alighnment,now that its out i would like to do a full and proper job because i might use this as my main contracting mower.i have heard that these hydro units cost $2000.00 plus...ken

Ken, I think we'll have to ask Bruce for help with this. The manuals section has some Peerless data, but it is only on manual transmissions and final drives.

Thanks grumpy,any info from bruce would be good.I shredded a belt on the other mower so while i was in town i asked the local mower shop of how confident their mechanic was on repairing the diff and the response and body language did not impress me let alone $75.00 an hour so i will proceed my-self...ken

There are two things you need, to be confident of a good job Ken: the manual, and any special tools that are actually required (rather than just nice to have). Well there are other things you need too, but you already have those (experience, patience and sense - but the first two are more or less interchangeable with each other).

UP-DATE,have been really busy after our little down pour.having trouble removing the wheel of the r/h axle-soak in wd-40-broke my wheel puller so i removed the circlip and the oil seal and was able to remove the right hand axle complete with wheel.the original problem of no drive was exposed with a broken r/h axle.i will take the wheel in to my mates place to use his press to remove the axle.next step is to provide a clean enviroment to split the diff in two to remove the remander of the axle.
grumpy,i will pm bruce to see if he can help me in a diaghram for the diff...ken

So, you now have an explanation of what went wrong with the mower, and it is something that should be fairly easily fixable. Just be glad it doesn't have a Posi-Traction car differential - I once twisted off an axle shaft at the inner end with one of those, and unfortunately some of the twist occurred in between the side gear and the clutch hub, so it could not be dismantled. Of course I did dismantle it - I drove the twisted stub right through both the side gear and the clutch hub by sustained use of a three pound hammer, since I didn't have a press at the time. Hardest part was getting the diff center out of the rear axle housing (it was a banjo axle). The broken axle stub stuck out far enough to prevent the diff center from coming out. Cunning use of levers eventually overcame the problem. Of course it would have been better to scrap the whole rear axle, but unfortunately the diff center was a heavily modified one that I couldn't replace. But I digress.

I agree Ken, PMing Bruce is the way to go. That axle is an expensive piece of gear, and working on it with a manual beside you is way safer than improvising. Doing it by ear is OK when you have no choice, but doing it by the book is much less stressful.

Hi grumpy and co,i have pm bruce with no reply (i know he is busy)but i am at a stand still in regards to accessing a diaghram of the diff...ken

ps,i emailed mtd australia last week with no reply.

We can try to do it from first principles Ken, if you post some pictures. It will be slow though, because we'll be guessing at times so you'll have to be very gentle and keep your eyes open.

ok grumpy,i emailed mtd to see if i could just buy the r/h axel or can a good welder(engineer) re-weld the broken axel or can i get one made up from billet steel?any way i will start to dismantel mine.
i also looked on u-tube to get some ideas and the workings of a hydro...ken

It is seldom feasible to repair an axle shaft that has failed. If it failed it wasn't strong enough in the first place, and welding it will make it weaker, not stronger. Most axle shafts are heat treated, and after welding the heat treatment is gone, and the repaired area is more or less normalised.

You need a new or used axle shaft. I think a new one is a good idea unless you find out what killed the old one, and can be sure it won't happen again.

Up-date,i split the diff in halves-had to so i could retrieve the inner part of the broken axle-nice and clean inside both halves.took the broken axle to a local engineer and he machined two flats on each end of the failed section -made up a sleeve section and using super lock,pressed sleeved segment onto both ends of the axle(broken section)then drilled and tapped in grub screws.now i have a complete axel again.put the axel back in and put the two halves together with gasket gue and let it sit over night.the correct oil is 20w40 but i need to find out how much to put in the diff.
i have taken photos of the diff and axle in halves so i will post them soon...ken

Are you sure the axle itself uses that engine oil Ken? It would be fairly unusual. The hydro unit normally uses light oil, but the axle unit usually uses heavy oil, and the two are kept separate - which they have to be anyway, because the axle unit usually accumulates a lot of fine particles of metal, and these would have a disastrous effect on the hydraulic pump and actuator.

I'm not saying it's impossible that the axle uses light oil, but because it would be quite unusual, I suggest you check carefully, and find out what the hydro uses, and what the axle unit uses. If they turn out to be the same stuff, you win the bet. If they don't, losing the bet is better than wearing out your axle unit with the wrong oil.