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'78 GT18 seems slow. Normal?


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#16 johnwesley OFFLINE  

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Posted February 02, 2015 - 10:07 PM

wahoowad, 

According to my Roper 18T manual, which should be same as your Sears, speeds are L1: .85mph, L2: 1.60 mph, L3: 2.56mph; H1: 2.10 mph, H2: 3.96mph, H3: 6.56 mph; R1: 1.02 mph, R2: 2.53 mph. Do yourself a favor and do not put a standard 5/8x83" belt on, get a kevlar wrapped mower belt. It lasts much longer, and its too much problem to be replacing often.

johnwesley


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#17 KennyP ONLINE  

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Posted February 03, 2015 - 05:31 AM

Guess we have ruled out a pulley change then?



#18 wahoowad OFFLINE  

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Posted February 03, 2015 - 07:05 AM

Yes, ruled it out. All looks stock.
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#19 MH81 ONLINE  

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Posted February 03, 2015 - 07:37 AM

Just wondering, with the OEM specs listed, what speed is it running at now?
Also, are you at 3/4- full RPM's?

#20 wahoowad OFFLINE  

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Posted February 03, 2015 - 11:23 AM

At this point I'll have to get it running up on my neighborhood street and see if my little handheld GPS gizmo will show me the ground speed.

 

I know my trans is still low on fluid as I changed it recently and never filled it up all the way. I tried but it was so darn slow to fill that I ran out of patience. I think i stopped after 3 quarts of SAE 30 as I knew i was close (think it calls for 3.5 quarts?) and I am not using the tractor for anything yet so didn't figure there would be any heat buildup. I added another 1/2 quart this weekend which was still very slow to fill even after I removed a shifter bolt to let air escape. The cold SAE 30 didn't help - it poured like molasses. I can't see this being responsible for the slowness though since I know I have a good bit of fluid in there.



#21 Alc ONLINE  

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Posted February 03, 2015 - 11:32 AM

If the incorrect belt was installed or worn so far that it either sat lower in the groves or bottomed in the pulley cause this problem ?



#22 TAHOE OFFLINE  

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Posted February 03, 2015 - 12:17 PM

Tranny holds 5 quarts.

 

you can remove one of the shifter plate bolts which go through into tranny, this vents the trans and lets oil flow quicker.

Also, get a pan of hot water, even getting it boiling then remove from burner and put quart of oil in there for a bit, helps warm and thin the oil.


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#23 johnwesley OFFLINE  

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Posted February 03, 2015 - 09:13 PM

Just wondering, with the OEM specs listed, what speed is it running at now?
Also, are you at 3/4- full RPM's?

That should be full rated RPM 3400-3600 RPM.  My old Roper has to wind up tight to cut clean. But, I'll tell you, it's pretty much a small "bush-hog" cutting 3"-4" limbs to mulch. I have taken the mower deck off, and pulled 6"-8" 25' logs out where I could cut them up and haul them off. I have never run out of power, but plenty of times run out of traction with 450- 600 lbs. of  extra weight. That old Onan doesn't know when to .quit.

johnwesley


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#24 wahoowad OFFLINE  

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Posted February 04, 2015 - 07:15 AM

That is what my GT18 will be doing - pulling stuff and probably never a cutter. I have a mower deck but looks in rough condition. I haven't really bothered to look at it to see what it would take to get it going. That is a project for when it gets warm :D


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#25 wahoowad OFFLINE  

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Posted February 06, 2015 - 08:06 PM

Got the tranny full of oil - heating up the oil helped tremendously! Thanks for the tip!


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#26 JBRamsey ONLINE  

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Posted March 09, 2015 - 09:26 PM

Do you have the right size tires on the rears? If you have a shorter tire on the rear, it will run slower. A shorter tire takes more turns(revolutions) to go the same distance.

#27 craftsmanmowerfreak OFFLINE  

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Posted March 09, 2015 - 09:49 PM

rear tires make a big difference. but my big ss 14 and ss15 will outrun my st10s. but my yellow st10 is running suburban tires on back and blue one is running 6-12s you can tell a big difference in speeds on yellow st10 compared to blue st10. but getting to transmissions my ss14 has a keyed axle trans and its a little quicker than my ss15 which i put a splined trans in.



#28 wahoowad OFFLINE  

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Posted March 10, 2015 - 10:37 AM

My GT/18 is running the original 23.5" tires.



#29 craftsmanmowerfreak OFFLINE  

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Posted March 10, 2015 - 11:13 AM

23.5 dont sound right should have 23-10.00-12, 23-9.50-12 or 23-10.50-12. one of those sizes on back



#30 wahoowad OFFLINE  

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Posted October 27, 2015 - 02:00 PM

I just checked and my tires are 23x10.00-12 (pretty sure stock tires). here is a close-up of my pulley system. Looks normal to me.

 

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