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Jarod Sheets
Joined: 27 Jan 2007
Posts: 125
Location: United States, Texas, Austin
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 Posted: Wed Aug 15, 2007 2:47 am Post subject: Seat position affecting weight distribution |
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If I simply increase the incline in my seat to lay back more without moving the "butt" of the seat forward at all, will it affect the weight distribution over the rear of the kart?
2nd Question...My seat is in the factory recommended position but I need about 3% more weight on the rear of the kart, is there any formula or tribal knowledge about how much to move the seat to get the required amount of weight movement?
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'07 CRG Road Rebel/Stock Moto
'06 First Kart V32/Adkins Parilla |
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J.J. O'Malley
Joined: 18 Oct 2005
Posts: 45
Location: United States, Texas,
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| Posted: Wed Aug 15, 2007 8:19 am Post subject: Re: Seat position affecting weight distribution |
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| Jarod Sheets wrote: | If I simply increase the incline in my seat to lay back more without moving the "butt" of the seat forward at all, will it affect the weight distribution over the rear of the kart?
2nd Question...My seat is in the factory recommended position but I need about 3% more weight on the rear of the kart, is there any formula or tribal knowledge about how much to move the seat to get the required amount of weight movement? |
#1. Yes, but not as much as if you moved the butt backwards
#2. How do you know you you need 3%? What is the kart doing? How far back is you motor? |
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Randy Lyon
Joined: 22 Dec 2004
Posts: 1363
Location: United States, Arizona, Scottsdale
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| Posted: Wed Aug 15, 2007 9:46 am Post subject: Re: Seat position affecting weight distribution |
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| J.J. O'Malley wrote: | | Jarod Sheets wrote: | | If I simply increase the incline in my seat to lay back more without moving the "butt" of the seat forward at all, will it affect the weight distribution over the rear of the kart? |
Yes, but not as much as if you moved the butt backwards |
Bet you wouldn't have said that if Jarodine had asked the question!   |
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Jarod Sheets
Joined: 27 Jan 2007
Posts: 125
Location: United States, Texas, Austin
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| Posted: Wed Aug 15, 2007 4:03 pm Post subject: Re: Seat position affecting weight distribution |
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| J.J. O'Malley wrote: | | #2. How do you know you you need 3%? What is the kart doing? How far back is you motor? |
I recently scaled the kart and had 45% front and 55% rear, perfect side to side. The kart gets a little loose in the rear from apex to exit. No problems with turn in. I just figured since typical weight values say 43/57~ish I should probably start there before moving anything else around. The motor cant go back to much farther, maybe 1" or so.
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'07 CRG Road Rebel/Stock Moto
'06 First Kart V32/Adkins Parilla
Last edited by Jarod Sheets on Wed Aug 15, 2007 5:25 pm, edited 1 time in total |
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Ed Scott
Joined: 21 May 2006
Posts: 155
Location: United States, Oregon, medford
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| Posted: Wed Aug 15, 2007 5:12 pm Post subject: |
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If you lower your center of gravity or your weight you will lose grip if you move it back it will add grip in the rear. Also moving it up higher adds grip.I only go level with the bottom of the rails no higher.
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Medford 2005 tag champ,2007 icc champ 2008 icc champ, 2009 80 and stock moto champ |
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Chris M Johnson
Joined: 14 Oct 2005
Posts: 568
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| Posted: Sat Aug 18, 2007 10:21 am Post subject: Re: Seat position affecting weight distribution |
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| Jarod Sheets wrote: | | J.J. O'Malley wrote: | | #2. How do you know you you need 3%? What is the kart doing? How far back is you motor? |
I recently scaled the kart and had 45% front and 55% rear, perfect side to side. The kart gets a little loose in the rear from apex to exit. No problems with turn in. I just figured since typical weight values say 43/57~ish I should probably start there before moving anything else around. The motor cant go back to much farther, maybe 1" or so. |
You are barking up the right tree. Shoot for manufacturer specs before doing any tuning. It wont respond unless the weights are right.
I am far from an expert, but checking my notes I see that 2cm of movement fore/aft was worth about .8% transfer. So figure an inch is about 1-1.5%. 2 inches may net you your 3%
If you are in the suggested seat position with a moto shifter in a rearward position, and you are a whole 3% off, that suggests to me that you are a light guy or the scales are off. I had the opposite problem and had to go forward of manufacturer spec, but ive got an intrepid and im fairly large for a karter.
Edit: Then some to think about it unless you are using the same seat that came from the CRG factory, the factory measurements are meaningless!! Give the wide variety of seats, use the weight %s exclusively for tuning.
Good luck!! |
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Jarod Sheets
Joined: 27 Jan 2007
Posts: 125
Location: United States, Texas, Austin
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| Posted: Sat Aug 18, 2007 11:09 am Post subject: Re: Seat position affecting weight distribution |
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| Chris Mahood wrote: |
You are barking up the right tree. Shoot for manufacturer specs before doing any tuning. It wont respond unless the weights are right.
I am far from an expert, but checking my notes I see that 2cm of movement fore/aft was worth about .8% transfer. So figure an inch is about 1-1.5%. 2 inches may net you your 3%
If you are in the suggested seat position with a moto shifter in a rearward position, and you are a whole 3% off, that suggests to me that you are a light guy or the scales are off. I had the opposite problem and had to go forward of manufacturer spec, but ive got an intrepid and im fairly large for a karter.
Edit: Then some to think about it unless you are using the same seat that came from the CRG factory, the factory measurements are meaningless!! Give the wide variety of seats, use the weight %s exclusively for tuning.
Good luck!! |
I started off with the seat in manf. specs and got the 3% off. I know I'm not using the same seat as they probably did, but I need a new one anyway. I figure I'll put a new Tillet in the same spot and weigh it out then I'll try using the thumb rule you posted up there. I'm definitely not a light guy (210). But my scales are pieces of crap so that may be it also. Thanks Chris.
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'07 CRG Road Rebel/Stock Moto
'06 First Kart V32/Adkins Parilla |
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Chris M Johnson
Joined: 14 Oct 2005
Posts: 568
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| Posted: Sat Aug 18, 2007 11:45 am Post subject: Re: Seat position affecting weight distribution |
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| Jarod Sheets wrote: | | Chris Mahood wrote: |
You are barking up the right tree. Shoot for manufacturer specs before doing any tuning. It wont respond unless the weights are right.
I am far from an expert, but checking my notes I see that 2cm of movement fore/aft was worth about .8% transfer. So figure an inch is about 1-1.5%. 2 inches may net you your 3%
If you are in the suggested seat position with a moto shifter in a rearward position, and you are a whole 3% off, that suggests to me that you are a light guy or the scales are off. I had the opposite problem and had to go forward of manufacturer spec, but ive got an intrepid and im fairly large for a karter.
Edit: Then some to think about it unless you are using the same seat that came from the CRG factory, the factory measurements are meaningless!! Give the wide variety of seats, use the weight %s exclusively for tuning.
Good luck!! |
I started off with the seat in manf. specs and got the 3% off. I know I'm not using the same seat as they probably did, but I need a new one anyway. I figure I'll put a new Tillet in the same spot and weigh it out then I'll try using the thumb rule you posted up there. I'm definitely not a light guy (210). But my scales are pieces of crap so that may be it also. Thanks Chris. |
Use a carpenters level and shims under each scale to make sure it is perfectly level. Also, calibrate each corner with 100lbs of weight plates if you have them. |
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