Need to run 9000rpm with these pipes. Anybody have any baseline clucthing that will get me close? Currently have all stock setup so the pipes overrev like crazy.
mopar1rules
Active member
What rpm are you turning now w/the stock setup? Probably like 9300?? What clutch components do you have to work with?
It's been awhile but I didn't want to chance it, about half throttle was 9000 I think. I'm guessing I could easily turn 10,000 if I wanted? All I have is what came stock with the sled.
That's why I'm looking for somewhere to start because I don't wanna spend a bunch of money that I don't have to.
With the stock pipe it was setup for about 8300-8500.
That's why I'm looking for somewhere to start because I don't wanna spend a bunch of money that I don't have to.
With the stock pipe it was setup for about 8300-8500.
mopar1rules
Active member
so what clutch components do you all have laying around to play with? maybe you can get a "close" setup w/what you already have??
I've got the 8DN-10 weights with a G-W-G primary spring. Green secondary spring with 45 deg helix.
That's all I have, it's what comes stock with the 05 Viper Mtn.
That's all I have, it's what comes stock with the 05 Viper Mtn.
mopar1rules
Active member
maybe try 8dn-20's w/4.5g both holes and 47 helix and y/w/y spring??
Alright, at least it's a place to start.
I dont think I would personally go buy another set of clutch weights, the 8dn-10 weights you have are the same profile as the 8dn20's, the 10's weigh 39.76 grams, the 20's weigh 42.09 grams. So it would be much more economical to just add weight to your current 10 series arms.
Also your clutch spring if its a g/w/g?? (I dont have the book on 2005 to look it up for you) is a 45/136kg, this is the stiffest long cap spring, this will raise the rpm also.
I would add weight to the front arms(heavier rivets with a washer if needed) and drop down to a white/white/white spring(45/119kg). this will do a couple things, drop the rpm because it will shift faster, and it will allow you to tune your weights in by adding rivets and possibly a washer on the rivet if its still high on rpm. Nothing really wrong with your 45 helix.
You have now found your engine makes considerbly more power when it over revs with previously correct rpm on clutching, just tame the spring down slightly because with the added power from the pipes you can now shift the sled faster without bogging it.
Also your clutch spring if its a g/w/g?? (I dont have the book on 2005 to look it up for you) is a 45/136kg, this is the stiffest long cap spring, this will raise the rpm also.
I would add weight to the front arms(heavier rivets with a washer if needed) and drop down to a white/white/white spring(45/119kg). this will do a couple things, drop the rpm because it will shift faster, and it will allow you to tune your weights in by adding rivets and possibly a washer on the rivet if its still high on rpm. Nothing really wrong with your 45 helix.
You have now found your engine makes considerbly more power when it over revs with previously correct rpm on clutching, just tame the spring down slightly because with the added power from the pipes you can now shift the sled faster without bogging it.
Buddy of mine ran a 159 srx in the mtns for years with DN-10's, 4.5 in each hole. Can't remember the spring off hand. Secondary was a 43, green at 70. I know that the srx runs slightly less rpm than your viper wants, but it gives you something to compare with. Sounds like the above info will get you pretty close to where it needs to be.
Should the sled also be geared up some too, along with what mrviper suggested?
Why would you want to gear it up? It's a mountain sled right? Most of the time the lower the better on those. You'll want at least a corrected ratio of 2 - 1 and if all it sees is hills and powder I'd shoot for something in the 2.2 -1 range.
Nah, this isn't my mountain sled anymore, this is my goof around "get-r-done"/"go-crazy" sled. I have an Apex Mtn I use as my mountain sled. This is more of a flatlands, coulee, go fast sled now. I figured since I have more hp now I could get a little more speed out of it.
One thing to remember.
When you raise the shift RPM on a sled you are effectively increasing its top speed capability as well.
For ex:
Stock
23/38 = 1.65:1 ratio
Stock shift RPM = 8500
at a shift ratio of 1:1, with 9 tooth drivers the sled is capable of approx 110mph
Piped/Mod setup
23/38 = 1.65:1 ratio
Mod shift RPM 9000[ 6% increase over stock]
at a shift ratio of 1:1 with 9 tooth drivers the sled is capable of approx 117mph[6 % increase]
As you can see raising the RPM by 6% is just like increasing the gearing by 6%
JM.02c
Bob
When you raise the shift RPM on a sled you are effectively increasing its top speed capability as well.
For ex:
Stock
23/38 = 1.65:1 ratio
Stock shift RPM = 8500
at a shift ratio of 1:1, with 9 tooth drivers the sled is capable of approx 110mph
Piped/Mod setup
23/38 = 1.65:1 ratio
Mod shift RPM 9000[ 6% increase over stock]
at a shift ratio of 1:1 with 9 tooth drivers the sled is capable of approx 117mph[6 % increase]
As you can see raising the RPM by 6% is just like increasing the gearing by 6%
JM.02c
Bob
Our Mtn Vipers are geared at 20/40 so thats why I was asking if I'm better of changing it a little bit.
sideshowBob said:
AMEN, somebody knows how it works, nice post!
I've got a spreadsheet that does that for me and then I don't have to think as hard as Bob did
dirtjumper895
New member
What did you end up using for a setup? I have a p85 loaded 10-58 with white/black square spring, 41/35 helix geared 20/40.
My sled runs right to 9050, but the shift seems flat. Im thinking about throwing the stock 45 degree helix back in.
My sled runs right to 9050, but the shift seems flat. Im thinking about throwing the stock 45 degree helix back in.
Right now I have the W-W-W spring as suggested with the 8DN-10s both holes have 13.3 stl (3.1g) in them. Green secondary spring wrapped at 70 with the stock 45 degree helix. Stock gearing at 21/40.
Pulls like a freight train until about 3/4 throttle. After that it's just like it loads the motor and nothing. On about a 0.5mile pull in about 8in of sugar snow it runs 80mph at about 9200rpm. On an ice/snow covered road it will run 95mph at about 9200rpm as well. (both dream speeds) From a dead stop it hits 9000rpm and holds it there slowly climbing to 9200rpm on top. Did see the DCS flash as well right at the end on the 95mph pull on the ice/snow covered road.
Not sure where to go with the cluctching from here. More weight in my clutch? Both clutches are hot hot to the touch so I know it still isn't right. Also running the 8DN belt. Anybody have ideas?
Pulls like a freight train until about 3/4 throttle. After that it's just like it loads the motor and nothing. On about a 0.5mile pull in about 8in of sugar snow it runs 80mph at about 9200rpm. On an ice/snow covered road it will run 95mph at about 9200rpm as well. (both dream speeds) From a dead stop it hits 9000rpm and holds it there slowly climbing to 9200rpm on top. Did see the DCS flash as well right at the end on the 95mph pull on the ice/snow covered road.
Not sure where to go with the cluctching from here. More weight in my clutch? Both clutches are hot hot to the touch so I know it still isn't right. Also running the 8DN belt. Anybody have ideas?
Last edited: