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Rob R

310-8 Ideal Drive Pulley size

By Rob R, in Transmissions and transaxles

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Rob R    966

Rob R
Posted

Hi guys luv my 310-8 did a total rebuild on the Magnum 10 Kohler last summer since she was blowing chunks of carbon, ring end gap was 40 plus, now with new rings, piston and hone job she is just about perfect. I want to now attack the drive speed she is too slow mowing in 2nd and too high in third. It has a 6 inch 5/ 8ths bore Drive pulley if I change to a 5 inch diameter pulley would this solve the problem (mowing in 2nd)?  assume going to 4 inch would be to much?  I also have a 4.5 inch.... any recommendations here would be appreciated. DO NOT want to do anything to hurt the transmission.  Thanks  

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wallfish    16,994

wallfish
Posted

IMO since the speed is a preference to you, do try changing the pulley and belt to the 5 incher and see how you like it. It won't hurt the trans and I've gone as small as 2.5 inches on there for a hot rod tractor. Then you can always go to the 4.5 or back to the 6 depending on your preference

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Rob R    966

Rob R
Posted
56 minutes ago, wallfish said:

IMO since the speed is a preference to you, do try changing the pulley and belt to the 5 incher and see how you like it. It won't hurt the trans and I've gone as small as 2.5 inches on there for a hot rod tractor. Then you can always go to the 4.5 or back to the 6 depending on your preference

Has anyone out there done this swap very interested in the results. Thanks 

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tom2p    2,394

tom2p
Posted
1 hour ago, Rob R said:

Has anyone out there done this swap very interested in the results. Thanks 


Andy did 

 

( Andy who ? - Andy from RedSquare  lol )

 

the thread is fairly recent - maybe this past summer 

 

Andy installed different pulley - and also installed LED lights 

 

if I can find the post - I will provide the link 

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ebinmaine    67,432

ebinmaine
Posted
2 hours ago, Rob R said:

Has anyone out there done this swap very interested in the results. Thanks 

I shrunk an engine pulley to reduce speed. Never tried to increase...

 

Went from a 4" engine pulley to a 2.5" so I could slow reverse down.

Worked great. I did have to adjust the tab at the end of the belt guard which is the belt guide.

 

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SylvanLakeWH    25,535

SylvanLakeWH
Posted

I have a 3.5” pulley on my rat rod C105 and she goes just fine... no issues... Predator 6.5 hp with stock 8 speed trans.

 

:twocents-02cents:

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Rob R    966

Rob R
Posted
3 hours ago, ebinmaine said:

I shrunk an engine pulley to reduce speed. Never tried to increase...

 

Went from a 4" engine pulley to a 2.5" so I could slow reverse down.

Worked great. I did have to adjust the tab at the end of the belt guard which is the belt guide.

 

Thanks Eric but I be talking 'bout the Tranny Pulley.... 

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Rob R    966

Rob R
Posted

Vinsrj gave me the following advice:

Hello! With the 8-speed transmission the 5/8" input shaft would be correct, as for a pulley size change I would start with a 5", that would speed up all of the gear ratios and may make 2nd gear a little faster and hopefully more to your liking, personally I believe WH got the pulley vs gear ratio right the first time when it comes to working these tractors, just make sure you do not replace the pulley with an aluminum Tractor Supply style pulley, get a good cast iron pulley,

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N875ED    98

N875ED
Posted

I installed a 3” pulley on the trans and now top out at 12 MPH on my 312-8. LOW-first gear is now about walking speed. Much better speed range for my taste.

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tom2p    2,394

tom2p
Posted
On 12/30/2019 at 5:52 PM, tom2p said:


Andy did 

 

( Andy who ? - Andy from RedSquare  lol )

 

the thread is fairly recent - maybe this past summer 

 

Andy installed different pulley - and also installed LED lights 

 

if I can find the post - I will provide the link 


darn - searching and searching and cannot find the thread 

 

and appears it was not 'Andy' (Andy R) - Andy did the LED lights but apparently it was someone else around the same time that did the pulley 

 

 

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Rob R    966

Rob R
Posted
17 hours ago, N875ED said:

I installed a 3” pulley on the trans and now top out at 12 MPH on my 312-8. LOW-first gear is now about walking speed. Much better speed range for my taste.

Good information what size drive belt did you finalize on believe the stock belt with a 6" Pulley is 5/8ths X 83"?  Thanks 

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N875ED    98

N875ED
Posted

I believe I installed a 78” belt, but I’d have to verify (and I won’t be in the shop until 1/6/20). I do know that only 1” made a huge difference.

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N875ED    98

N875ED
Posted

Confirming that a 3" OD pulley on the transmission and a 78" drive belt work quite well together...doubles the top speed but still has good slow speed crawl.

 

One note: you may have to modify a new woodruff key...the input shaft key slot is narrower than the milled slot on the new pulley (5/8" dia shaft). Buy a new key (to fit the wider pulley slot) then file away the crescent side to make if fit into the input shaft...takes about 30 minutes.

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Rob R    966

Rob R
Posted

Okay so the pulley came-in today, took off the 6" OEM and put on a 4.5" pulley with no issues. I really like the difference in the speed of 2nd speed high to mow the grass..... I took it out for a pretty good test this afternoon …… ME LIKEY …..  thanks to all for the helpful suggestions..... Think I will end-up with a 5/8ths 80 or 81 inch belt. I had a 1/2 X 79 laying around and used it for the test. Worked well. 

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