clutching question

[smog]

I have a Max IV 2008 with a Bandolero engine, the original 790 primary clutch and the original T20 clutch + red spring.

the belt is brand new

The engine look like it is held at low rpm and can't downshift under load. I can hear the belt crying sadly under the rear hood and the engine working at a way too low rpm for a Bandolero. (it look like the Bando is forced in a kubota like rpm range)

When I changed to the red spring, I reinstalled the ramps with a 120 deg preload. IS IT POSSIBLE it wasn't enough and the driven is opening way too fast ?

also how often people are readjusting the valve clearances ? (I'm looking at every possible cause for the low performance)

[smog]

part of the problem was a wrong spring on the throttle return so I wasn't able to get the throttle plate wide open

now how does the red spring look like inside your driven ? mine is not sitting evenly as it is in an argo drive I have here..... but the red spring look like it is in his spot.

[JohnF]

A recent discussion on 6x6world sent me to the books to understand the theory of operation of CVT clutches. I even had an ongoing email/phone conversation with a tech at well known CVT manufacturer R&D facility to verify what little I know. I am in no way an expert.

You can get Olav Aaen's "Clutch Tuning Handbook" for a great intro to what is going on in these things. I asked and was told I could not share a pdf version I found.

Caveat: I do not know which clutch you have, the specifics of your engine, or any mods/changes you've made, and I assume the clutches are clean/lubed and working properly.

My gut tells me that you need lighter flyweights but from the book you have 4 options:
Stronger primary spring (same rate)
lighter flyweights
more pretension in the secondary spring
less cam angle on the helix.

Not downshifting seems like you need more pretension on the secondary spring. I didn't know Max used clutches with adjustable helix ramps.

From my reading:
make sure you have enough squeeze force so that the belt operates properly then power issues are solved in the drive pulley and shifting issues are solved in the driven pulley.

Too bad you are so far away, I would love to be of help. It's always great to match theory to practical.


[EDIT] DOH! I guess we were on at the same time.

So, after fixing the throttle problem - how is the clutching behaving and what are you trying to change? (Is it still the low RPM problem?)

[smog]

the primary is ok and was ok before the driven spring swap but I will have a ride with the Max before going back inside the tub as messing with the driven in a Max IV is a pretty bad job.

and I already got the clutch handbook but my problem is not about tuning, it's more like solving an assembly issue

[msafi65]

The driven with a red spring is supposed to be rotated from the relaxed position past two cam bumps. The spring when wound does touch the side at times. I just finished a bandelero in an Argo and the low end isnt there. I believe the camshaft is for the higher rpm. Sounded like my old muscle cars with the exaust open. Not sure what our clutch issues will be yet,this thing flies!

[smog]

The driven with a red spring is supposed to be rotated from the relaxed position past two cam bumps.

so it's more like 240 deg from the relaxed position. where did you get that info ?

[msafi65]

From Jay at RI and found it in Salisbury manual this morning. If you only loaded past one cam it will convert as soon as it gets moving and won't downshift unless you nearly stop. I know you have to pull the trany to fix this one. Hope this helps
went back to the manual and it said 1/3rd turn or 120 degrees, two cam bumps gets it done. good luck

[Tomo]

hi
Max are equipped with 700 series primary and secondary
There are many differt variations to chose from also
The most common primary is a 780 which is fitted to max
There are many versions of the secondary 770 , 780, 790 speed or torque sensative etc
770 has the lowest 1st gear ratio and the slightly slower top speed
780 thru to the 790 having the highest first gear ratio and the highest top speed ratio
THE max is fitted with the 780 secondary torque sensative type 28 degree ramping

The comet secondary on the max is the third generation type unit
UR able to determine which generation by the slipper colour and quantity fitted
1st gen 3x white slippers
2nd gen 3x black slippers
3rd gen 6x black slippers

The other optional components are the ramp angles of the secondary avaiable in 26, 28 32 35 41 degree ramps
Ther lower angle ramps retard up shift eg keeping u in a lower gear 4 longer
Once this has been established then u can fine tune with springs


tomo

[smog]

I know you have to pull the trany to fix this one.

well I found a trick so I only have to remove the engine stand to do it.

[Hogneck]

the primary is ok and was ok before the driven spring swap but I will have a ride with the Max before going back inside the tub as messing with the driven in a Max IV is a pretty bad job.

and I already got the clutch handbook but my problem is not about tuning, it's more like solving an assembly issue

Off the subject Smog,I was wondering what your belt deflection on your Max IV might be.Mine seems to be alot compared to what they say it should be @ 1 1/8 to 1/14'' .I believe mine is high side of 2 or 2 1/8'' but it does not slip and it runs ok to my knowledge. 18hp vangard.

[Hogneck]

well I found a trick so I only have to remove the engine stand to do it.

Be interested to know that trick! prettty tight spot to work on secondary clutch in the Max IV.

[smog]

just to preload the spring, will loosen the driven bolt to give me enough space to remove the snap ring and crank it one more ramp.

trick is to add 3 tie raps to the spring so you don't have to fight against it.

[msafi65]

Cool I' ll have to remember that one. Ive usually got other issues also and have to pull the tranny. Thanks

[smog]

if you want to completely remove the driven, the only way is to remove the T20 ... sad but it's the only way.

[micmac]

2X what Smog said. I recently changed out my secondary spring. Looked at all options, pushing the tub out etc..only way is pulling the T-20. Too bad because on the Hustler it will slip off between the tub and the T-20. If the Max had a 1/2 inch more clearance you could get it off