Sat Sep 03, 2022 5:21 am

Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
 
Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
Sat Sep 03, 2022 5:21 am linkquote
Hi guys, Vespa 50s 1975 (V5SA1T), kitted 75 polini.

Clutch sucks, its in the limbo between dragging when pulled and slipping under torque, very hard to get a decent adjustment and making it work as a clutch should. I think its a newfren 4 plate, one central spring.

What would you recommend? I've done a search on SIP/SC and Polini Molla wave evolution looks neat, anyone has one of those?

Thanks
Sat Sep 03, 2022 9:22 am

Enthusiast
Rally 180, TS 125, PX 150 and a lot of smallies
Joined: 19 Oct 2013
Posts: 95
Location: Paso
 
Enthusiast
Rally 180, TS 125, PX 150 and a lot of smallies
Joined: 19 Oct 2013
Posts: 95
Location: Paso
Sat Sep 03, 2022 9:22 am linkquote
Sounds like the spring is coil binding to me. A 75cc kit isn't more powerful than an ET3. I would used a stock clutch. Good luck.
Sat Sep 03, 2022 10:44 am

Veni, Vidi, Posti
'15 GTS300, '86 PX125EFL, '66 VBB, '04 Ninja 250
Joined: 04 Apr 2013
Posts: 6525
Location: San Diego, CA
 
Veni, Vidi, Posti
'15 GTS300, '86 PX125EFL, '66 VBB, '04 Ninja 250
Joined: 04 Apr 2013
Posts: 6525
Location: San Diego, CA
Sat Sep 03, 2022 10:44 am linkquote
3 plate with Polini spring. Malossi spring sucks, gets coil bound.
Sat Sep 03, 2022 4:01 pm

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11846
Location: The state of insanity, SoCal
 
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11846
Location: The state of insanity, SoCal
Sat Sep 03, 2022 4:01 pm linkquote
double check the thickness of the clutch pack-- corks and steels, to make sure it's not too thick.

I'd run the wavy gravy spring on that, or with just a stocker.
Sat Sep 03, 2022 4:57 pm

Veni, Vidi, Posti
'15 GTS300, '86 PX125EFL, '66 VBB, '04 Ninja 250
Joined: 04 Apr 2013
Posts: 6525
Location: San Diego, CA
 
Veni, Vidi, Posti
'15 GTS300, '86 PX125EFL, '66 VBB, '04 Ninja 250
Joined: 04 Apr 2013
Posts: 6525
Location: San Diego, CA
Sat Sep 03, 2022 4:57 pm linkquote
btw the 4 plate setups tend to warp on the plates. it's a blessing and a curse to go 4 plates. the tabs get thin and wear out faster too.
Sat Sep 03, 2022 10:48 pm

Hooked
Parmakit Primavera -74, Polini Primavera -68, Stock 150 Touring -59, VMC 177 Bajaj Chetak 125 -95
Joined: 22 Jun 2022
Posts: 415
Location: Finland
 
Hooked
Parmakit Primavera -74, Polini Primavera -68, Stock 150 Touring -59, VMC 177 Bajaj Chetak 125 -95
Joined: 22 Jun 2022
Posts: 415
Location: Finland
Sat Sep 03, 2022 10:48 pm linkquote
Regular Primavera clutch will do just fine. Three plates and regular spring will work. No need for beefing things up, just remeber to use bog plain SAE30 lawnmower oil in your engine.

Your current intermediate discs are likely warped and there is not enough separation between the discs for the clutch to disengage completely.
Sun Sep 04, 2022 12:18 am

Member
Joined: 25 Jul 2021
Posts: 16

 
Member
Joined: 25 Jul 2021
Posts: 16

Sun Sep 04, 2022 12:18 am linkquote
Some good suggestions already. Just a thought to add... Double check your cable isn't binding anywhere. I had issues with mine for a while and it turned out the old cable was too long in the frame, I had similar problems that you've described.

Also +1 for a standard 3 plate and polini wave spring
Sun Sep 04, 2022 12:26 am

Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
 
Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
Sun Sep 04, 2022 12:26 am linkquote
Thanks all for the feedback, follow-up later…
Best Regards
Tue Sep 06, 2022 1:59 am

Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
 
Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
Tue Sep 06, 2022 1:59 am linkquote
Hi again, one question for the experts ...

What is the practical effect of having a 4 disk clutch where the disks are 2.45mm (actual), as opposed to a clutch with 4 disks which are 1.9mm thickness ?

Does it impact the clearance on the clutch lever?

Thanks!
Tue Sep 06, 2022 2:33 am

Hooked
Parmakit Primavera -74, Polini Primavera -68, Stock 150 Touring -59, VMC 177 Bajaj Chetak 125 -95
Joined: 22 Jun 2022
Posts: 415
Location: Finland
 
Hooked
Parmakit Primavera -74, Polini Primavera -68, Stock 150 Touring -59, VMC 177 Bajaj Chetak 125 -95
Joined: 22 Jun 2022
Posts: 415
Location: Finland
Tue Sep 06, 2022 2:33 am linkquote
Thinner plates mean more room for the discs to separate when you pull in the clutch. On the downside less material to wear and possibly distorts even easier due to lower mass.
Tue Sep 13, 2022 6:40 am

Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
 
Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
Tue Sep 13, 2022 6:40 am linkquote
Hi, balancing pros and cons, opted for a Fabbri racing FB24 clutch.
In hope it performs accordingly with price tag

Thanks for the suggestions!
No more upgrades to vintage Vespas... Game Over!
Wed Sep 14, 2022 3:30 pm

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11846
Location: The state of insanity, SoCal
 
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11846
Location: The state of insanity, SoCal
Wed Sep 14, 2022 3:30 pm linkquote
why'd you go so high end on the clutch? a proper set of plates and correct spring would be more than adequate and 1/4 the cost.
Thu Sep 15, 2022 3:01 am

Hooked
64 V90 survivor '65 Allstate survivor. '75 V90 SOLD. '77 P200 SOLD
Joined: 30 May 2018
Posts: 390
Location: Madison WI
 
Hooked
64 V90 survivor '65 Allstate survivor. '75 V90 SOLD. '77 P200 SOLD
Joined: 30 May 2018
Posts: 390
Location: Madison WI
Thu Sep 15, 2022 3:01 am linkquote
As mentioned check the length of your clutch cable outer.
When I re cabled my 64 V90 the outer had a 90 degree bend in it was very stiff.
Shortened the outer and smoothed it right out


Check this bend

Thu Sep 15, 2022 5:41 am

Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
 
Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
Thu Sep 15, 2022 5:41 am linkquote
greasy125 wrote:
why'd you go so high end on the clutch? a proper set of plates and correct spring would be more than adequate and 1/4 the cost.
That would be a more rational option indeed. After my post and some of the answers I had very good feedback from owners (2) that did upgrade to one of these multi spring clutches ... "It works like the one you have on the large frame".

Bottom line: I took the safer option although costly
Thu Sep 15, 2022 5:45 am

Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
 
Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
Thu Sep 15, 2022 5:45 am linkquote
exmayor wrote:
As mentioned check the length of your clutch cable outer.
When I re cabled my 64 V90 the outer had a 90 degree bend in it was very stiff.
Shortened the outer and smoothed it right out
Yeah, thanks, my outer sleeve is new. Old one was cracked in one place and was heavy as hell. Easy to replace attaching old and new with a wood screw with head off ... it was easy to pull
Thu Sep 15, 2022 5:53 am

Banned
2:6
Joined: 11 Jan 2007
Posts: 8309
Location: San Francisco
 
Banned
2:6
Joined: 11 Jan 2007
Posts: 8309
Location: San Francisco
Thu Sep 15, 2022 5:53 am linkquote
what is your primary drive gearing? is it still the stock 50 (16/68)?

The lower the primary gearing, the higher the torque seen by the clutch. So if you put a kit on the 50 without increasing the primary ratio you will need a ridiculous clutch to hold back even a small amount of torque at the crank.

On our 50 Special when we put the 102 on it, it would slip at anything over half throttle. Installed a 90 primary (22/63) and a newfren 4 plate clutch with the stock clutch spring. this gave a stock effort at the clutch lever, higher top speed, and enough clutch to hold the massive power of the 102
Thu Sep 15, 2022 7:30 am

Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
 
Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
Thu Sep 15, 2022 7:30 am linkquote
Yes, its still the stock 16/68.

Engine was upgraded with a 75 Polini cylinder, Polini banana exhaust, racing crank shaft, Vespatronic ignition, lately with a SHBC 19 carburator with a 82 jet which proved to work the best. Its pulling nicely.

Last ride in 4th gear, my guess nearly 40mph. it suddenly slipped to max revs !
I was really pushing it hard, but slipping at those hi revs really surprised me. Maybe if I loosen the clutch cable 1mm it would not slip but then riding among trafic with stops and starts at low gears is a pane, clutch grabs even when engaged... I know, putting in neutral before stopping and "launch mode" on resume... nice ...
Thu Sep 15, 2022 3:14 pm

Banned
2:6
Joined: 11 Jan 2007
Posts: 8309
Location: San Francisco
 
Banned
2:6
Joined: 11 Jan 2007
Posts: 8309
Location: San Francisco
Thu Sep 15, 2022 3:14 pm linkquote
lever choice on the smallframe clutch can also have a big impact.

Some levers don't give enough travel for the cable to disengage the clutch.
Fri Sep 16, 2022 6:47 am

Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
 
Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
Fri Sep 16, 2022 6:47 am linkquote
oopsclunkthud wrote:
lever choice on the smallframe clutch can also have a big impact.

Some levers don't give enough travel for the cable to disengage the clutch.
Thanks for the info. I think mine are ok, they are indeed in a greater angle and very far from the handlebar when compared with my large frame.
Thu Sep 22, 2022 8:22 am

Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
 
Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
Thu Sep 22, 2022 8:22 am linkquote
I know you guys like pics, this thing looks awesome.
Pressure plate runs on bearings, butter…





Thu Sep 22, 2022 11:49 am

Banned
2:6
Joined: 11 Jan 2007
Posts: 8309
Location: San Francisco
 
Banned
2:6
Joined: 11 Jan 2007
Posts: 8309
Location: San Francisco
Thu Sep 22, 2022 11:49 am linkquote
the stock small frame clutch also has "forced oil injection system"
Thu Sep 22, 2022 12:12 pm

Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
 
Hooked
125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
Joined: 04 Aug 2014
Posts: 226
Location: Madeira Island
Thu Sep 22, 2022 12:12 pm linkquote
oopsclunkthud wrote:
the stock small frame clutch also has "forced oil injection system"
Lol, yes. They're learning with Apple
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