05 m7 not enough rpms clutch help please!

[josey]

2005 m7 153" slp twins, timbersled intake, bd box riding 10,000-12,500' in about 2 feet snow, with all stock clutch setup for 9000 and over, yellow primary white secondary spring and 65g weights. while climbing my sled would only pull around 7100 rpms it would do a little more at lower elevations. on a trail at top speed was only getting like 7500. i just installed shift assist in secondary along with the bd billet deflection adjuster. I was getting 7800 in the flats before installing shift assist and deflection adjuster. I hate to go to lighter weights as 65s are already light, would a stiffer primary spring help. also should i try cranking in the secondary spring, or even try a stiffer spring like the cat orange everyone talks about? sorta new to clutching just what i know from these forums thanks.

 

[dgreet77]

Lots of options here....this is what I'd do.

1. Check power valves/servo; make sure they are not sticking at all and that the cable adjustment is right at 34.5mm.

2. Make sure you're deflection is set up right. I think the measurement is 1-1.25 inches deflection measured from laying a straight edge across the clutches and pushing the belt down until it starts to tighten; then measure up to the straight edge. Mine almost squeaks at idle on my '05 M7 with the AMP adjuster.

3. Make sure the secondary spring adjuster is .5 inches in from the outside of the cover. Might need a set screw for the adjuster if it keeps backing out. Don't screw the adjuster in any more than this or it may cause the spring to bind.

This will be all the free stuff anyways. I'm not sure what the target RPM is with the twins and intake. But I would guess if you get it back up to 7800-7900 you'd be about right.

Also I think its common to loose 100-200 RPM's with the shift assist. And also I don't think most tach's on these sleds are dead on...more like off by 100-200.

If none of the above helps you might need to change you're clutching setup for the pipes and intake. I have the same clutching (minus the shift assist) as you though with an RKT head and porting and the sled rips. Good Luck!

 

[josey]

Lots of options here....this is what I'd do.

1. Check power valves/servo; make sure they are not sticking at all and that the cable adjustment is right at 34.5mm.

2. Make sure you're deflection is set up right. I think the measurement is 1-1.25 inches deflection measured from laying a straight edge across the clutches and pushing the belt down until it starts to tighten; then measure up to the straight edge. Mine almost squeaks at idle on my '05 M7 with the AMP adjuster.

3. Make sure the secondary spring adjuster is .5 inches in from the outside of the cover. Might need a set screw for the adjuster if it keeps backing out. Don't screw the adjuster in any more than this or it may cause the spring to bind.

This will be all the free stuff anyways. I'm not sure what the target RPM is with the twins and intake. But I would guess if you get it back up to 7800-7900 you'd be about right.

Also I think its common to loose 100-200 RPM's with the shift assist. And also I don't think most tach's on these sleds are dead on...more like off by 100-200.

If none of the above helps you might need to change you're clutching setup for the pipes and intake. I have the same clutching (minus the shift assist) as you though with an RKT head and porting and the sled rips. Good Luck!

Thanks for the post its good to hear the shift assist does lower rpm i thought i was trippin. I am quite sure i have everyting you mentioned squared away. the deflection seemed a little tight around an inch from the straight edge when the belt is pushed untill the the lower portion of the belt starts to just tighten. The track barely creeps on a jack stand at an idle and it dosent squeel when hot. i picked up some 63g weights will try that thanks

 

[dgreet77]

Thanks for the post its good to hear the shift assist does lower rpm i thought i was trippin. I am quite sure i have everyting you mentioned squared away. the deflection seemed a little tight around an inch from the straight edge when the belt is pushed untill the the lower portion of the belt starts to just tighten. The track barely creeps on a jack stand at an idle and it dosent squeel when hot. i picked up some 63g weights will try that thanks

Sounds good to me too. I'd say your deflection is probably prime. Funny you'd have to drop weight with the intake and pipes; you'd think with more power you'd have to add weight?

Oh; one thing to consider is if you've had you're power valves out to clean them and you put them back in upside down they wouldn't open all the way/like they should and this could be robbing your RPM's....

Good Luck!

 

[HELLCAT7]

The 63 gram weights and orange secondary were the ticket for me in the same places you are riding. Actually black/orange speedwerx secondary would be best as the cat orange is just a touch toooo stiff.

 

[colorado logger]

Your m7 should swing the 65. I ran a speedwerk pipe with 65's at your elev.
My shift was 8300 in the deep and more in the track. But saying all of this don't really matter your twins could require lighter weights.

How's your fuel settings, do you run egt's?

 

[josey]

I tried the 63s at rabbit ears and buffalo pass like 9000-10500' and was getting plenty of rpm, I saw 8400 one time. I also adjusted the bd box transition points down two points because it was staying in med when climbing last time out, so I think that may have changed everything cuz the sled ran great. Just not sure if it was changing the bd box, changing weights, or changing elevation. guess thats why you change one thing at a time when tuning. I think the 65s would be better at the lower elevation, and 63s higher up, but will have to test up there again. The one problem i see is when i hit the nitrous, even a small shot will peg the tach like i need more weight guess its a tradeoff. Any suggestions?

any way thanks for the help, cant wait to smoke my buddies this season!

 

[dgreet77]

I think the 65s would be better at the lower elevation, and 63s higher up, but will have to test up there again. The one problem i see is when i hit the nitrous, even a small shot will peg the tach like i need more weight guess its a tradeoff. Any suggestions?

65's at lower and 63's higher is what you should go with if they are giving you the desired RPM. Remember you're sled will make more power the lower in elevation you are so it can spin more weight. Having said this I think 8400 is way too high. Stock M7's are at their best at 7700-7900. Also having said that...I like to run mine right at 8020 or slightly higher due to some porting and aftermarket head.

Same thing with the Nitrous...you're making that much more power when you hit it, so more weight would keep the RPM's down, but since you are not spraying constantly it is a trade off between keeping RPM's in a safe range when on the juice and having them high enough when you're not. Maybe try some 64's and see if it is a better balance.

I hope this helps!