CV-Tech to Comet 780

[kellett5261]

So I finally had some spare time and removed my CV-Tech clutch & installed my comet 780 . would it be common to lose roughly 8-9 MPH?

Im not 100% on the hole "weight" changing thing and springs, I'd rather get someone's advise before I just start throwing money back at it.

I do know that VC quit carrying the CV clutch and don't offer it anymore, would it be easier to just pull apart the CV and fix whatever the issue is with that? OR just change out the weights/springs in the Comet.

My rig ran about 37-38 mph, it wasn't so much about the speed but i wanted the highest cruising's speed at the lowest RPM, (which was around 25ish at 2,000) I ran out of daylight today but according to my gps the cart is at 4500 rpm and I'm only doing 30-31.


Thoughts?

[raydhd]

For lower rpm engagement and shift over on my comet 780 I have the 68 gram weights and green springs in place of the original VC set up of 108 gram weights and yellow springs. Along with a double cogged 1 1/4" belt with very little slack in it.

[kellett5261]

Originally Posted by raydhd

For lower rpm engagement and shift over on my comet 780 I have the 68 gram weights and green springs in place of the original VC set up of 108 gram weights and yellow springs. Along with a double cogged 1 1/4" belt with very little slack in it.

So do you think but changing the weights and springs on the 780 will give me back that higher RPM? I tried to find specs on the CV clutch and could find anything nor what weights are in the 780 currently installed .

I saw you mentioned very little slack in the belt …. Would more slack speed your cart up? I’ve never really messed with it but my clutches had to be re aligned so they line up and the belt is slightly tighter than it was .

I have 6:1 gears on 22” tires and was running 38 max at like 4800 rpm . Only reason I’d like to get back to the higher speed is “if” I go on main road to the grocery store I’d like to have that extra speed if needed.

I do like the comet rpm engagement and how smooth it is but I’m all ears on making it better

Thanks

[slonomo]

Speed should be determined by the engine rpm and your final drive ratio. If the two clutches are the same diameter they would have the exact same top speed at the same rpm. If the diameter's are different, that could account for your speed loss. Also, belt position/size will affect the speed as well. If your belt fits different, looser that with the old clutch, that will affect your top speed.

Clutches will not affect the engine rpm, only how the power is delivered/transfered. Engagement rpm will not affect top speed, neither will shift profile. With that said, your speed at a given rpm might change based on the two clutches, but not your "max rpm speed" once full shift is achieved.

[kellett5261]

So I found another used/new condition CV-Tech Series 06 HD Drive Clutch on ebay, looks like its still in very good condition. I am making an assumption that the weights/springs are much higher in the CV with higher take off RPMs

[slonomo]

Could be. I'm wondering if the CV clutch is a larger diameter diameter vs. the 7 1/4" diameter of the 780? That would account for some speed loss at full shift.

[raydhd]

2 notes on spring and weight changes 1 Unless you are cruising at full shift rpm it will make quite a difference in cruising speed at lower rpms. 2 The back shift will also change again allowing a much lower rpm cruise after the shift over. So for cruising I will run up to the 3000 rpm or so shift over back off the throttle and cruise in the full shift over mode down to about 2000 rpms. P.S. I don't know what the weaker green springs would do with heavier weights.

[kellett5261]

Originally Posted by slonomo

Could be. I'm wondering if the CV clutch is a larger diameter diameter vs. the 7 1/4" diameter of the 780? That would account for some speed loss at full shift.

i wanna say my take off engagement was around 2000 with the CV, I'll have to measure them side by side when i get home, they are close to the same size though, only major difference was the offset or set back was slightly different so I had to loose the engine plate and slide it over to align it. my new engagement rpms are much lower, I can barely touch the gas and it will take off, the CV wouldn't necessarily shake the cart but it wasn't as smooth. if that make sense.

Originally Posted by raydhd

2 notes on spring and weight changes 1 Unless you are cruising at full shift rpm it will make quite a difference in cruising speed at lower rpms. 2 The back shift will also change again allowing a much lower rpm cruise after the shift over. So for cruising I will run up to the 3000 rpm or so shift over back off the throttle and cruise in the full shift over mode down to about 2000 rpms. P.S. I don't know what the weaker green springs would do with heavier weights.

ill give this a try today after work, this is typically what I would do with the CV, I always had lots of chatter from the driveline under a hard take off, maybe it was the belt not being tight enough or possibly the clutch . Would the belt having more or less slack cause overall speed to change? just curious.

[raydhd]

Picture the optimum top speed is where the belt is at the very top of the primary and at the very bottom of the secondary. So if the belt is too loose it will not be pulled as deep into the secondary conversely if it is too tight it will not have the length to get to the top of the primary.Again having the belt exactly the right length increases the speed/RPM ratio across the board. I also found the 1 1/4 " belt with a thicker cross section will rider higher in the primary giving a higher top speed. You can see how you are doing with an accurate tach and speedo.

[kellett5261]

Originally Posted by raydhd

Picture the optimum top speed is where the belt is at the very top of the primary and at the very bottom of the secondary. So if the belt is too loose it will not be pulled as deep into the secondary conversely if it is too tight it will not have the length to get to the top of the primary. I also found the 1 1/4 " belt with a thicker cross section will rider higher in the primary giving a higher top speed.

Awesome POV, with that being said I have to the VC engine mount, you can adjust it front to back and has another mounting slot to move from side to side, I only adjusted the engine side to side and then reinstalled the belt and the belt was already much tighter than it was on the CV compared to the 780 & I didnt even move the engine to make it tighter.

that makes perfect sense if that's my issue, as for a belt i am just running a Vegas 47" belt, I am not sure of the thickness of the belt. I'd like to switch to a nice gator belt or dayco if I could figure out the size but i'd be on my own for that one.