lawnmower drive pulley question

This has probably been asked before and I am sorry if it has. So I have another side project going and I was wondering. I have a craftsman with a 14.5 hp engine and a spicer rearend. I am going to do a pulley swap on the engine and rearend this time. The spicer I expect to not last long. So I measured the stock drive pulley which is also attached to the mower pulley. The drive part measures 4-1/2 wide and with a 1Inch ID off of the crank shaft. So what size pulley should I run in the front so it does not rub on the tensioner pulley? I am going to go with a 5inch on the rear so it does not slip. I had a 3-1/2 inch on the rear of my Dynamark and I got a lot of belt slipping. So my questions are
what size pulley can I go with on the front so it does not rub?
What kind of rearend should I go with on the rear that has the pulley on the top that will bolt up to my craftsman where the stock spicer is? Peerless 801? I want something durable.
I have been told I should put a 3/4 inch belt on and let it wear down and that will prevent slipping.. Anyway as usual your comments are appreciated.

Around what speed are you wanting to go? I have an 11hp Dynamark that had i think a 3in pulley on the engine and a 6 or 7in on the back and i swapped the trans pulley out for a 5 in and it'll go around 10 mph now. And i didn't even touch the engine pulley.

My previous pulley swap topped out at around 18mph. I only swapped the one on the rearend. I would like to hit around 30mph.. Not extremely important that I hit that speed. I am more focused on building a durable build.

Ideally you want the biggest pulley size you can fit on there to reduce belt slip, but sometimes that's easier said than done. For example, I have a 75mm (3inch) on the front because that's the biggest i can use with the stock clutch. Once I change the clutch Ill put a 118mm (4 5/8inch).
Belt slip can be down to the clutch not applying the correct tension to the belt or the belt could have stretched.

I have heard that Spicer's aren't as strong as the peerless gearboxes but at the end on the day, both makes use aluminum casings so there are still weak. Personally I would go for a 801 if you can get one or do anyway with the gearbox all together and use a T-Drive. Ill be keeping my 901 until I brake it then Ill get a T-Drive.
Why not keep your Spicer until it brakes then consider if you want gears or if you want a fixed ratio.

What kind of tractor were you using? Spicers are junk for sure.

My tractor is a Dynamark, same as TennesseeCowboy's tractor but with a 4 speed peerless.

Peerlesses are the best then probably a foote and spicer is just a joke.. lol

Well, on my 85 LT12 i put a 6" motor pulley - the clutch idler pulley hit the motor pulley with a screech - Id say depress the clutch to its hilt, and mesure how far away from the factory pulley it is - id say maybe you could go another inch bigger and thats it.

Other then custom building a new clutch, thats pretty much the limit.


Youd be surprised on minor pulley swaps what speeds you can get , depending on tire size and trans ratios on how fast it can go.

On my 6 speed murray with a 6" motor and 3" trans pulley - that thing was scarey fast past 3rd gear ( ran 8" rims all around) - my agway i did a minor pulley swap, a 4" motor pulley and a 8" trans pulley and the stock 3 speed trans ( just looking for lil more then geriatric stock speed - nothing blazing fast) - 1st/2nd were normal - 3rd launched me to about 10/15mph.

CornishMorgan wrote:

My tractor is a Dynamark, same as TennesseeCowboy's tractor but with a 4 speed peerless.

By 4 speed do you mean 1,2,3 with reverse or 1,2,3,4?

I have a spicer and it's so far held up well, considering what I've thrown at it. Jumping, downshifting to stop, hauling a trailer full of logs out of the woods up hill, and even pushed a car. So far, nothing bad. For my pulley swap, I used a 3" on the rear and a 5" on the front. I then used two idler pulleys on an adjustable bracket to take up the belt slack. Gets me almost to 20 MPH on a 6 speed spicer.

TenneseeCowboy's tractor is like my '82 dynamark - its a 3 speed with reverse, actually my 80's agway has the same trans under it.

I haven't had any problems out of my Peerless and to my knowledge its the stock one from 20+ years ago lol

The nice thing about the peerless 3 speeds with reverse is that a new one only cost about 80 to 100 new and they can take a beating