Author Topic: Fork oil for 45mm right side up forks  (Read 307 times)

Offline Petrus Rocks

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Fork oil for 45mm right side up forks
« on: March 18, 2019, 03:51:38 PM »
I just transplanted a set of 45mm MG adjustable forks onto my 85 Tonti frame.  I see 485cc per leg as a spec but no height measurement.  Also MG calls for 10wt oil.  Anyone use something different? 
Pete

Offline John A

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Re: Fork oil for 45mm right side up forks
« Reply #1 on: March 18, 2019, 04:05:29 PM »
actually I like to use motor oil.  I learned from some racing types that forks cant read so they don't know if you don't put in high zoot fork oil or not.  Ive been using 15/50.
John
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Online Perazzimx14

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Re: Fork oil for 45mm right side up forks
« Reply #2 on: March 18, 2019, 04:06:26 PM »
ATF also works a treat
I'm overweight but identify as skinny, I'm trans-slender!

Online Rough Edge racing

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Re: Fork oil for 45mm right side up forks
« Reply #3 on: March 18, 2019, 06:14:42 PM »
 Fairly big gap between 15/50 and ATF , usually described as a 7.5 weight oil....considering forks run much cooler than an engine or transmission...it's still a big difference...
I ride junk, some of it actually goes fast

Online Perazzimx14

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Re: Fork oil for 45mm right side up forks
« Reply #4 on: March 18, 2019, 06:37:13 PM »
Fairly big gap between 15/50 and ATF , usually described as a 7.5 weight oil....considering forks run much cooler than an engine or transmission...it's still a big difference...

15/50 might be a bit excessive or have all dampening and slooooooooooooooooo ooo rebound. I've run straight 30w oil in the forks of my Eldorado with success.
I'm overweight but identify as skinny, I'm trans-slender!

Offline Rick4003

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Re: Fork oil for 45mm right side up forks
« Reply #5 on: March 18, 2019, 10:25:01 PM »
I just looked into getting some new fork springs for mine and Wilbers recommend 7.5w oil with their fork springs.
Moto Guzzi 850 T5 (850 sport) - 1985
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Yamaha FZR 600 - 1996

Online Rough Edge racing

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Re: Fork oil for 45mm right side up forks
« Reply #6 on: March 19, 2019, 05:08:08 AM »
 Pete, since the forks assembly on the bike now is from a heavier machine than your "cafe" Tonti, perhaps a slightly lighter oil might be better to prevent harsh dampening...Maybe 5 weight fork oil instead of the slightly heavier ATF.. I'm assuming the 45 mm forks were not under dampened on the original bike...
  For those interested, the 45 mm later forks on the 80's Tonti frame bike look very nice, a more balanced look with the large Guzzi engine...The original 35 mm forks look like they belong on a 250cc bike in comparison... :grin:
I ride junk, some of it actually goes fast

Offline Petrus Rocks

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Re: Fork oil for 45mm right side up forks
« Reply #7 on: March 19, 2019, 08:10:47 AM »
Good point Tony.




image uploader

Here's a before and after.  Steering stem triples, and bearings all fit right on.  Using the old Borrani rims I will have to make a spacer to center the wheels.  A simple bracket will allow me to use the old calipers.  I have a set of four pot Brembos that will go well with larger discs.

Offline Petrus Rocks

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Re: Fork oil for 45mm right side up forks
« Reply #8 on: March 19, 2019, 08:17:30 AM »
Didn't realize that was a such a crappy picture...


 

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