Author Topic: 1993 SPIII Bitubo Fork Damper Rebuild??  (Read 1608 times)

Offline 93spada

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1993 SPIII Bitubo Fork Damper Rebuild??
« on: March 25, 2017, 05:31:36 PM »
Hi Folks
I have done as much googling that I can take.
I saw some notes in a G5 post in 2014 about drilling and putting oil in but they are different dampers I think.
Has anyone rebuilt the dial adjustable dampers?
I like to take things apart, clean and repair them if possible.
I am just not sure yet how to disassemble them.
Please help.
See pics below.
Thanks
Paul







upload multiple images

Got the circlip out and tried to turn the plug gently to no avail.



This is the bottom that goes into the fork stantion.
PJM

Offline Chuck in Indiana

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Re: 1993 SPIII Bitubo Fork Damper Rebuild??
« Reply #1 on: March 26, 2017, 05:52:46 AM »
Yeah, I've done it.. but like most things it's lost in the cobwebs of time. I do remember that you can over fill the cartridges and they will lock up. I'll see if I can find it in the archives.

Edit: Found it in my journal, and all I said was 
10-18-13
Overhauled the Strada fork dampers. Piece of cake

so, it must have not been hard. I'd left my camera at the kid's at the time, so the only picture I have is taking the top off.. you've already figured that out. It *seems like* the cartridge just unscrewed, though. Are there a couple of holes in the top for a spanner, or was that another project?
« Last Edit: March 26, 2017, 06:19:01 AM by Chuck in Indiana »
Chuck in (Elwood) Indiana/sometimes SoCal

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Offline 93spada

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Re: 1993 SPIII Bitubo Fork Damper Rebuild??
« Reply #2 on: March 26, 2017, 09:36:49 AM »
Thanks Chuck!!!
Piece of cake is what I wanted to hear.
It does seam pretty straight forward. We tried a couple of tools to unscrew the top plug but was going to beat it up.
I think I will get my fab buddy to make another Guzzi wrench. Part # will be PJM45082/B.
McMaster Carr will probably have all the parts needed.
Thanks for the tip on overfilling.
I will post more pics as we go.
Thanks again.
Paul

PJM

Offline blackcat

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Re: 1993 SPIII Bitubo Fork Damper Rebuild??
« Reply #3 on: March 26, 2017, 12:47:32 PM »
The 1000S has the same forks. I have replaced the springs with a set of Wirth springs and I shimmed them for some extra support, but I did it years ago and have no memory of the forks. My SPIII was a low mileage bike so there never was a need to touch them.

I should look at those forks so keep up the posts, so I can steal your knowledge.
boom shakalaka
http://youtu.be/wHUP527txeg

1968 Norton Fastback
1976 Lemans
1981 CX-100
1993 1000S
1997 Daytona RS
2007 Red Norge

Online flangeman_70

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Re: 1993 SPIII Bitubo Fork Damper Rebuild??
« Reply #4 on: March 26, 2017, 03:13:32 PM »
If you can wait a month or two I am going to a rebuild on a set and document it here.
Why wait, if you look at this thread http://wildguzzi.com/forum/index.php?topic=65449.0there is a lot of good information, BUT I have since learnt a lot more and recently rebuilt mine to a good working setup, although, I need lighter oil in the cartridge. The spare set I have will have bushes machined into them using Cali 1100 fork tubes :grin:
The plastic pieces you show are for helping the bump stops I think as in the 1100 fork tube there is a hole just above the bush unlike the SPIII style tubes.
You need this kit to rebuild the cartridge in the fork http://www.stein-dinse.biz/Moto-Guzzi/Fork/Others/Gabelstossd-Bitubo-Rep-Satz-f-verstellb-YBE-YBC::15033.html disregard my previous parts for the cartridge in the BiTurbo thread but use the sliders I suggested, they are far superior.
What most don't know is that the bottom of the cartridge has a bump stop and if this has failed then instead of getting a progressive bump stop, you get hydraulic lock :sad:

Regards,

Adam.
You only went to school to learn how to learn

Adam

SP III 1990
V10 Centauro 1996

Offline 93spada

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Re: 1993 SPIII Bitubo Fork Damper Rebuild??
« Reply #5 on: March 27, 2017, 07:35:14 AM »
Blackcat, Will do.
Adam, Thank you!!!! I will get a little deeper and post pics. It will not be a complete photo tutorial as I am learning as I go.

What oil wgt did you end up with? We have .05 and 7wt in stock.

Also, on the fork tube there is a hole, (sorry no pic), about 10in x 1/8" from the bottom of the tube.
It was on the rear of the tube ( towards the engine). Is that an oil drain back/stanchion lube hole?
Can that be rotated 180 to be in the front to offset wear on the tube and stanchion?

Thanks Again!!!!
Paul
PJM

Offline blackcat

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boom shakalaka
http://youtu.be/wHUP527txeg

1968 Norton Fastback
1976 Lemans
1981 CX-100
1993 1000S
1997 Daytona RS
2007 Red Norge

Offline 93spada

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Re: 1993 SPIII Bitubo Fork Damper Rebuild??
« Reply #7 on: March 27, 2017, 09:29:22 AM »
I was wondering the same.
Will let you know if they are in there when I tear them apart.
Maybe travel stops?
Maybe internal damper rod centering devices to keep the short end inside from bending when fully extended??
Paul
PJM

Online flangeman_70

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Re: 1993 SPIII Bitubo Fork Damper Rebuild??
« Reply #8 on: March 27, 2017, 12:40:08 PM »


What are those black strips?

Those are the cartridge piston seals. Only one set is used in our fork type :wink:

Adam
You only went to school to learn how to learn

Adam

SP III 1990
V10 Centauro 1996

Online flangeman_70

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Re: 1993 SPIII Bitubo Fork Damper Rebuild??
« Reply #9 on: March 27, 2017, 12:54:34 PM »
Adam, Thank you!!!! I will get a little deeper and post pics. It will not be a complete photo tutorial as I am learning as I go.It's exactly what I did and the results are good. Unfortunately I could not get the cartridge apart without maring it a little. That bottom piece was in there for good so I used a pipe wrench and vice and a hot torch to get it to pop :popcorn:

What oil wgt did you end up with? We have .05 and 7wt in stock.In the cartridge I used Putoline HPX 7.5W It is a little too heavy for the fast bumps so I am going to try 5W. I will also polish the compression shim face of the valve so it gives a better seal. There is no rebound shim just ports which are metered by a conical needle. There are two O rings in here and this is probably where it is leaking the clear fluid from. The needle is Crude but effective, spherical coned needles are linear, straight side cones are more like exponential. I've got the rebound all the way open so a lighter weight will help there too.

Also, on the fork tube there is a hole, (sorry no pic), about 10in x 1/8" from the bottom of the tube.
It was on the rear of the tube ( towards the engine). Is that an oil drain back/stanchion lube hole? Yes
Can that be rotated 180 to be in the front to offset wear on the tube and stanchion? Yes

You only went to school to learn how to learn

Adam

SP III 1990
V10 Centauro 1996

Offline 93spada

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Re: 1993 SPIII Bitubo Fork Damper Rebuild??
« Reply #10 on: March 27, 2017, 02:18:15 PM »
Adam,
Thanks!!
Thanks and thanks.
Just for the heck of it, I am checking with the Herdan Corp. and Bellissimoto here in the US to see if I can get that rebuild kit. For me from Stein-Dienes it is the 69euro plus 30euro for shipping.

Cant get to it til this Wednesday so I will post pics that night.
Paul
PJM

Offline 93spada

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Re: 1993 SPIII Bitubo Fork Damper Rebuild??
« Reply #11 on: March 27, 2017, 05:39:57 PM »
Just got a note back from Bellissimoto.
Bitubo Rebuild kit is #GR0024
Not in Stock
2-3 weeks from Italy
$65us plus $9us shipping.

The Stein-Dienes site had a reference of YBC and YBE in their header for the part.



Just saw it when speaking to Herdan.
Waiting for a reply from them before doing anything
Paul
PJM

Offline 93spada

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Re: 1993 SPIII Bitubo Fork Damper Rebuild??
« Reply #12 on: May 18, 2017, 04:32:35 AM »
Hi Folks
Going to get back at this rebuild today. Had a family issue that delayed it.
Ordered rebuild kit from Bellissimoto on 4/25. just got kit yesterday. Had to be ordered from Italy.
$65us plus $9us freight. The key to order is the YBE / YBC kit for my adjustables.
Pics and notes to follow as time allows
Paul
PJM

Online flangeman_70

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Re: 1993 SPIII Bitubo Fork Damper Rebuild??
« Reply #13 on: February 02, 2019, 06:21:08 AM »
You only went to school to learn how to learn

Adam

SP III 1990
V10 Centauro 1996

 

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