1980 MTD 918 - 'Ol Rusty!

I always thought that series of Dynamark had an awesome paint job. I wonder if any of them had right angle gearboxes instead of a belt twist.

RichieRichOverdrive wrote:

I always thought that series of Dynamark had an awesome paint job. I wonder if any of them had right angle gearboxes instead of a belt twist.

I agree about the paint, I also like the hood how it jets out the sides a bit too. Pretty cool!

Made a mount for an exhaust pipe:


Doesn't look too bad installed! Loud as hell though, need to get a muffler on the tip or something otherwise I fear the valves will eat dust.


Now, the transaxle has been whining a bit, and I figured since the tractor is in the garage and thawed out I'd check the oil level. I previously drained and refilled it will 80w-90 gear oil, but now it's this thick, green/yellow oil? Oil came out of the top fill port so I don't think it's low? Do you guys think that's water in the trans somehow?

What do you all recommend for oil? Something thinner maybe?

If air can get in, water can.  Water tends to cloud the oil though.  If those are pieces in the oil I would change it.  Could be some rust flakes.  80-90 is good.  That's what that trans calls for and is what I run in my 2300's.  Anything thinner could cause some seals to leak.  Ah, just looking at that pic made me smell it.

If you like the noise don't worry about a muffler, you have enough header pipe to protect the valves. I'm running a shorter pipe than you with no issues.

I agree with @MightyRaze 80w90 is perfect, probably looks nasty because of the old stuff mixing with the new and yes there's probably a little moisture mixed in but I wouldn't change it until the weather warms up or it will end up looking the same. Oil suspends moisture that makes it in, running in the cold will do that because the oil gets warm then condensation will form once it starts to cool.

MightyRaze wrote:

If air can get in, water can.  Water tends to cloud the oil though.  If those are pieces in the oil I would change it.  Could be some rust flakes.  80-90 is good.  That's what that trans calls for and is what I run in my 2300's.  Anything thinner could cause some seals to leak.  Ah, just looking at that pic made me smell it.

Yeah the old stuff was pitch black and smelt real strong lol

Brianator wrote:

If you like the noise don't worry about a muffler, you have enough header pipe to protect the valves. I'm running a shorter pipe than you with no issues.

I agree with @MightyRaze 80w90 is perfect, probably looks nasty because of the old stuff mixing with the new and yes there's probably a little moisture mixed in but I wouldn't change it until the weather warms up or it will end up looking the same. Oil suspends moisture that makes it in, running in the cold will do that because the oil gets warm then condensation will form once it starts to cool.

That make sense about the condensation, also how doe you know if you have enough pipe to protect the valves? Just need a turn basically to add some back pressure??

Reversion of cold air hitting the exhaust valve is what causes damage it has nothing to do with backpressure, as long as you have at least 3-4" inches of pipe the air has trouble making it's way back. Backpressure is a myth of sorts in the sense that it's not desirable.

Brianator wrote:

Reversion of cold air hitting the exhaust valve is what causes damage it has nothing to do with backpressure, as long as you have at least 3-4" inches of pipe the air has trouble making it's way back. Backpressure is a myth of sorts in the sense that it's not desirable.

Ahh okay so I'm good in that case. Thanks for clarifying!

I added another pipe to help dampen the sound a bit:


I know it's just electrical conduit but it works and it's pre-bent lol.
I'll probably end up welding it together, and I'll definitely paint it black with vht paint

I use conduit all the time for exhaust.  No shame in it. 

I concur, conduit works great and is pretty strong to boot! Because it's galvanized it's best to sand as much of the coating off it that you can before paint or it flakes off pretty easily (in my experiences).

I'm going to offer a word of caution for your consideration because I don't want to see you put alot of time and effort into something you might not be happy with in the long run... running a stack has it's place. For a tractor that's more for utility, pulling or going to spend most of it's time in mud and open spaces they're awesome! They look and sound cool, I love the 2 I have even though they are in my face loud! If you're planning on doing more woods/bush/technical riding then a stack is risky, they like to get caught on trees/bush, can snap off easily (possibly damaging your head) and if you roll over and have your leg stuck under it for even a second you're going to lose it! Lol. You'll notice most ATTs have the exhaust down and either out the side, out front or out the back.

Sorry for the rant!

Brianator wrote:

I concur, conduit works great and is pretty strong to boot! Because it's galvanized it's best to sand as much of the coating off it that you can before paint or it flakes off pretty easily (in my experiences).

I'm going to offer a word of caution for your consideration because I don't want to see you put alot of time and effort into something you might not be happy with in the long run... running a stack has it's place. For a tractor that's more for utility, pulling or going to spend most of it's time in mud and open spaces they're awesome! They look and sound cool, I love the 2 I have even though they are in my face loud! If you're planning on doing more woods/bush/technical riding then a stack is risky, they like to get caught on trees/bush, can snap off easily (possibly damaging your head) and if you roll over and have your leg stuck under it for even a second you're going to lose it! Lol. You'll notice most ATTs have the exhaust down and either out the side, out front or out the back.

Sorry for the rant!

No need to apologize for the rant! I have thought of that, and I was concerned about it as well. I might flip the exhaust around so it points to the ground later on. I do love the stack look but you are absolutely right, it I tip it or it gets snagged, it's gonna suck. I wanted to go higher with the stack but opted not to for the same reasons!

Ever poke a straw through a potato in school? It's all I think of should a front end roll over happen. That's the biggest reason I don't do a stack. That and exhaust fumes in my face.

MightyRaze wrote:

Ever poke a straw through a potato in school?  It's all I think of should a front end roll over happen.  That's the biggest reason I don't do a stack.  That and exhaust fumes in my face.

Ewwww
True though! And honestly, the stack looks great but it's LOUD so I'm going to look into another way to route the exhaust that lets me put a muffler on it. I'm thinking a muffler on the end of the stack would look weird lol.

Anyways, got home extra early today so I added a belt brake prototype and wired in the lights only to find out one is burnt out  

@Silver_Pharaoh what size is the taper lock pulley and where did you buy it?

@Crazy_Carl I'm not sure where his came from but I've heard that This place is a good spot

Crazy_Carl wrote:

@Silver_Pharaoh what size is the taper lock pulley and where did you buy it?

Got mine from Princess Auto, it's a "BK70" sheave pulley, here's the manufacturer website: https://www.usarollerchain.com/BK70-Pulley-1-Bore-p/bk70-1-pulley.htm

That one is 6.75" in Diameter

Moved the exhaust, no more burny burny if I flip it or walk by it after it's been running!

Also mucking around with the electrical system. Got the battery to charge, but voltage climbs to 16.5v at 4000rpm. Not ideal. Just have a bridge rectifier on it right now. I think I'll eventually replace the 3A coil with either two 3A coils I'll wire in parallel or find a 10A coil and buy the voltage regulator for that 10A coil.

Need to add more belt brakes too, unless it's idling, the belt never really stops spinning with the clutch in.

And got some time this afternoon to rig up the remote throttle!




Need to drive it more to let a feel for it better, but so far it's pretty good!
Next is fix the slipping steering and get the front wheels mounted better

What was that pedal originally?

RichieRichOverdrive wrote:

What was that pedal originally?

Ironically, brake lol