transmission 8 speed vs hydo

[boatman 3]

B)

I have a 312 hydro and was wondering about changing it to

an 8 speed. Is the frame the same as far as where the trans bots

on? Also will all the 8 speeds from C series and 300 400 series

all bolt up the same? How much differnce in strength is there from

the c series to the 400 series? Thanks

[stevebo-(Moderator) 8,590]

Boatman,

I believe the frames are the same. Most of the C's have a 1 1/8 inch axles which are the same on the 400 series. I think you are asking for a lot of work to swap it over. IMO I would buy an 8 speed and if you are short on funds then sell your hydro. In the end you will have what you want without the hassle and added cost of the swap. I have been there and it is a lot of work and more mmoney than you intially believe it to be. Good luck-

[boatman 3]

B)

Thanks SteveBo, You are probably right. I was just kind of curious

if it could be done, and just toying with the idea. I mow alot and the

312 h only has a 42" mower. I'm a fraid with the power loss due to being

a hydro that it won't handle a 48" like my c-125 8 speed does. Did

they ever make any 414 hydros? All I've seen is the 8 speeds.

[stevebo-(Moderator) 8,590]

Good question, I have not seen any 414 hydros either. Got look for a nice 500 series if you wnat to run a 48 inch deck B)

[nylyon-(Admin) 8,321]

They didn't make a 414-Hydro (at least in the US). If the hydro is good, you're better off trading it than swapping it (in my opinion anyway). 12HP is on the smaller side to run a 48" deck regardless of hydro or 8-speed. I know that the hydro's "rob" some power, but the variable ground speed should more than make up for it in the end. I'm biased towards the hydro's anyway.

[boatman 3]

B)

I have run 48" on my c-125 ever since it was new{1982} and never

have had any problem however I mow regularly so grass isn't six

inches high ever. Last summer I bought a 414-8 speed and it does

it a little easier with the 48" deck. I've put ag tires on c-125 and have

it set up just to work in guarden. [ mold board plow, disc, tiller] It

does great.

[kpinnc 15,718]

On average, at least as a rule of thumb anyway, a perfectly functioning hydro robs about 4 horsepower. I'm sure there is some parasite drag on the 8 speeds too, but it is much less.

A 10 horsepower tractor will run a 48 inch deck, and many of the older machines (1054, etc...) often used them. Of course, fuels today aren't of the same "kick" as they used to be either.

There were two different models of the 312 hydros: the 312-A, and the 312-H. They are VERY different from one another.

A 300 series hydro-to-8 speed swap is fairly easy. The center column was stamped out to accept both transmissions and linkages, and of course the frame is identical. But if your tractor is a 312-H, and not a 312-A, then you have to find a mechanical lift arm to replace the hydraulic lift on the -H model. The only part to find and replace from a 312-A and a 312-8 is the clutch/ brake rod assemblies. It's a piece of cake really.

312-H to 312-8, not so easy.

If you've serviced the 312 hydro, replaced the belt, etc, and still have issues, then the 8 speed is the way to go. If you do indeed have a 312-H, you've got the same rear end as a 520-H, so it should be fairly stout. The 1100 series Eatons are hard to beat.

The 700 series on the 312-A is kinda weak, and have a bad reputation for going bad. They just don't have the output torque required for the application. Plus, they use a separate oil chamber than the rest of the transaxle, meaning there is no filtering at all for the fluids. One little bit of dirt, and it's all over.

Kevin

[Horse Fanatic 51]

I have a 312-A that I converted to an 8-speed. It wasn't difficult and took maybe 3 hours but I had a complete donor machine so I had all parts available to make the swap. It's not as simple as bolting a different tranny on, the brake levers are different, you add a clutch pedal and so forth. If you come across an 8-speed machine with a blown engine cheap, go for it.