Author Topic: 38mm triple clamps for a Tonti  (Read 442 times)

Online JayDee24ca

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38mm triple clamps for a Tonti
« on: May 03, 2021, 08:18:53 PM »
Were any Guzzis equipped with 38mm triple trees that will fit on a Tonti? I have a Convert, for which I am planning on building a leading link front end, and the stock Convert triple clamps are 35mm, too small for the 1 1/2 inch (38mm) tubing I want to use. Turning down the 38 mm to 35mm is not an option at this point. I will use .120 wall DOM, although I have recently be told I should consider chromoly 4160. Either way, I would like to find a set of 38mm triple clamps that will fit on the Convert with a minimum of hassle.
JD
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79 G5
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Offline Cdn850T5NT

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Re: 38mm triple clamps for a Tonti
« Reply #1 on: May 03, 2021, 08:35:22 PM »
850T5 and SP II's use 38mm.T5 ones do not have that little "eye" on the top one for instrument mounts. Not sure re SPII ones. They actually may be the same as the T5 ones.

I think the ones in the photo are the SP II ones... which makes the above comment wrong...



« Last Edit: May 03, 2021, 08:38:02 PM by Cdn850T5NT »
1985 Eurospec 850 T5 NT (Nuovo Tipo - New Type... i.e. Series III)

Online JayDee24ca

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Re: 38mm triple clamps for a Tonti
« Reply #2 on: May 03, 2021, 08:48:10 PM »
850T5 and SP II's use 38mm.T5 ones do not have that little "eye" on the top one for instrument mounts. Not sure re SPII ones. They actually may be the same as the T5 ones.

I think the ones in the photo are the SP II ones... which makes the above comment wrong...




Well, shoot! If the T5/SPII will fit, that would make my life a WHOLE lot easier! Any idea if the stem size is the same as the Convert?
'74 Nuovo Falcone
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79 G5
the rest are all gone.....

Offline Cdn850T5NT

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Re: 38mm triple clamps for a Tonti
« Reply #3 on: May 03, 2021, 09:11:47 PM »
Don't know... but fork spacing is another aspect. I think mine are 195mm.
1985 Eurospec 850 T5 NT (Nuovo Tipo - New Type... i.e. Series III)

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Re: 38mm triple clamps for a Tonti
« Reply #3 on: May 03, 2021, 09:11:47 PM »

Online Antietam Classic Cycle

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Re: 38mm triple clamps for a Tonti
« Reply #4 on: May 03, 2021, 09:32:24 PM »
Well, shoot! If the T5/SPII will fit, that would make my life a WHOLE lot easier! Any idea if the stem size is the same as the Convert?

Since the steering head is taller, the stem will be longer, but diameter is the same.
Charlie
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Offline leroy_can

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Re: 38mm triple clamps for a Tonti
« Reply #5 on: May 03, 2021, 10:01:14 PM »
I have a set of t-5 forks with trees. Definitely 38mm and looks like 180mm wide at a quick measurement but I had thought they were 182 wide for some reason. The steering stem appears quite long. I can measure them just let me know which dimensions you need.
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Offline Cdn850T5NT

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Re: 38mm triple clamps for a Tonti
« Reply #6 on: May 04, 2021, 12:16:30 AM »
Don't know... but fork spacing is another aspect. I think mine are 195mm.

If there are two fork spacings, and I think there are, my T5 forks are the narrower... so they must be 180's... Sorry 😐.
1985 Eurospec 850 T5 NT (Nuovo Tipo - New Type... i.e. Series III)

Offline jwinwi

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Re: 38mm triple clamps for a Tonti
« Reply #7 on: May 04, 2021, 10:22:27 AM »
Can the 35 mm triple clamps be safely bored out to 38 mm?  :popcorn:
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Re: 38mm triple clamps for a Tonti
« Reply #8 on: May 04, 2021, 10:58:12 AM »
Can the 35 mm triple clamps be safely bored out to 38 mm?  :popcorn:
Yes, done both with LM1 triples to fit Marzocchi 38 forks as well as with LM2/T/T3,SP etc. Works a treat
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Online JayDee24ca

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Re: 38mm triple clamps for a Tonti
« Reply #9 on: May 04, 2021, 11:46:50 AM »
Can the 35 mm triple clamps be safely bored out to 38 mm?  :popcorn:
Well that indeed is the question! It would certainly be the simplest route, but I am not convinced it is the best. I looked at the meat around the existing 35mm bores, and wasn't too keen on making it much thinner. Granted we are talking only about 1/16 inch (3mm) per side, but the top clamp is only 82mm thick at its thinnest, and the lower clamp just over 95mm. Not being a metallurgist or engineer, I can't say for sure if these numbers would allow for any removal of material and still meet the stress and loading requirements of a bike front end, especially as a leading link and sidecar introduce a huge amount of lateral stresses on the forks that are not apparent in a solo machine.   
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Online JayDee24ca

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Re: 38mm triple clamps for a Tonti
« Reply #10 on: May 04, 2021, 11:58:02 AM »
The Convert/G5/T3 triple clamps have fork spacing ctr to ctr of 195cm. and clamp spacing (at the steering neck) of 182.5, according to the workshop manual drawings. I don't have a set SPII or T5 drawings to compare it too, and they do not appear of Greg B's site either.
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Offline leroy_can

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Re: 38mm triple clamps for a Tonti
« Reply #11 on: May 04, 2021, 12:18:13 PM »
   I have the T-5 (38mm)ones I mentioned and a set from a 500 Benelli (35mm)which I believe are both manufactured by Marzocchi. They are both 180 centers and the bottom seems to be the same casting for both, same overall width so I would say the bottom would be safe bored out but the top while looking very similar has more meat on the T-5 ones and I wouldn't want to bore the Benelli top one out to 38mm . I believe the stems can be swapped from one to the other in most cases.
1973 XLCH cafe Shovester #1
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Offline Cdn850T5NT

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Re: 38mm triple clamps for a Tonti
« Reply #12 on: May 04, 2021, 04:16:07 PM »
Please note that there are three (3) series of T5... with the Series I bike having the shorter steering head tube, Series II and III having the long neck... The SP II only has the long steering neck tube.

I think the "axle" can be pressed-out to swap 'em 'round, i.e. take your old "axle" and put it in place with your newly-procured upper and lower triple clamps if nec.
« Last Edit: May 04, 2021, 04:18:09 PM by Cdn850T5NT »
1985 Eurospec 850 T5 NT (Nuovo Tipo - New Type... i.e. Series III)

Offline jwinwi

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Re: 38mm triple clamps for a Tonti
« Reply #13 on: May 04, 2021, 04:25:36 PM »
Someone posted the thread size and pitch of the stem recently so you could add more thread and cut down the stem to match the length you need. Have also heard of others pressing out the old stem and pressing in a new one...
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Online JayDee24ca

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Re: 38mm triple clamps for a Tonti
« Reply #14 on: May 04, 2021, 08:22:10 PM »
It sounds as though I would need to find a set of later 38mm T5 clamps that have the same 195mm fork spacing, and the two little nubbins for mounting the instrument/fairing. Does such a unicorn exist?
'74 Nuovo Falcone
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Offline harrytief

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Re: 38mm triple clamps for a Tonti
« Reply #15 on: May 04, 2021, 08:43:19 PM »
I have a set of the 40mm forks from an sp3 (I think) with the fork spacing at 195mm. Will that work for you?
Harry

Offline 1down5up

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Re: 38mm triple clamps for a Tonti
« Reply #16 on: May 04, 2021, 09:40:52 PM »
Someone posted the thread size and pitch of the stem recently so you could add more thread and cut down the stem to match the length you need. Have also heard of others pressing out the old stem and pressing in a new one...

No, I don't believe you can as the machined bearing surface is located at the right hight for the long neck frame, the steering stem then slightly redues in size so you can get the bottom bearing all the way down.

If you try and cut the thread longer the bearing will not locate on the stem.


Offline Cdn850T5NT

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Re: 38mm triple clamps for a Tonti
« Reply #17 on: May 05, 2021, 12:02:01 AM »
It sounds as though I would need to find a set of later 38mm T5 clamps that have the same 195mm fork spacing, and the two little nubbins for mounting the instrument/fairing. Does such a unicorn exist?

Confirming that all T5's have 180 mm fork spacing, not 195. Will bet same for SP II's. I am a bit surprised if an SPIII has 195 spacing... but they are 40 mm fork tubes and they may run more than 110/90's by way of tire size... so they may indeed be 195's for clearance sale.
« Last Edit: May 05, 2021, 12:03:10 AM by Cdn850T5NT »
1985 Eurospec 850 T5 NT (Nuovo Tipo - New Type... i.e. Series III)

Online JayDee24ca

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Re: 38mm triple clamps for a Tonti
« Reply #18 on: May 05, 2021, 01:57:41 PM »
I have a set of the 40mm forks from an sp3 (I think) with the fork spacing at 195mm. Will that work for you?
Harry
Harry, thanks for the suggestion, but I think I am going to work with these original Convert/G5 trees, and use some heavier steel for building the forks. The SPIII would definitely offer my more options for tire size, which is a good thing for running a rig, but I think I will stick with original. If it doesn't work out I may be in touch with you!
'74 Nuovo Falcone
'79 Convert
79 G5
the rest are all gone.....

 


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