Why no grass dragging of our Deeres?

[jdxrobin]

Looking at the really fast Yamahas from Delaughter racing, their suspension was a cross between slides and bogies. They do not run a hyfax at all (bare aluminum rails) but instead have 4 axles with 4 or 5 wheels between the rails. I asked the guy about it and all he said was friction is bad...
As far as weight transfer, the really fast sleds just took straight off...No skis were lifted at all. To that point, the rear wheels were huge, they looked like they were somewhere around 8-10 inches in diameter, yet the sled sat almost straight, right on the ground. I am assuming had something to do with the weight transfer issue.

[Cabindweller]

I was told once that the energy spent lifting the front off the ground is energy wasted in forward motion. Makes sense to me, but I know nothing about it.

Jerry

[liquidatorkid]

that does make pretty good sense, that's what I'm curious about with a bogie wheel sled and the weight transfer it seems as you start to accelerate the rear idlers (on a jdx chassis) would squat the most then going from the rear forward each set of bogie's would have decreasing pressure on them, as the front of the sled lifted up, it seemes like a bogie wheel style sled would have an advantage over a slide rail style susp. because on acceleration if the susp. isn't set up properly then when the skis lift the front of the track lifts off the ground and the only part of the track that is getting traction would be a smaller surface area from the rear idlers forward, while a bogie wheels would keep the track parallel to the ground it seems

i did get the info on the local vintage grass drags and here's what i found out

Hilltop Vintage Grass Drags

5 Classes – Must have leaf springs and be 1985 or older, working tethers and working brakes.

Time: Registration: 9:30 – 10:45.
Racing @ 11:15 Sharp.
No Exceptions!

Cost: $10.00 per driver.
$5.00for each additional class.
Dates:
Oct. 08, 2011
Nov. 12, 2011
Dec. 10, 2011
Jan. 07, 2012
Feb. 18, 2012
Mar. 17, 2012

1961 Heselton Gully Rd.
Andover, NY 14806
Questions – Call:
Jason 1-607-478-8197
Mike 1-814-848-7512

class 1
1. all single cyl.
2. twin cyl. up to 340cc with single carb and single exh.

class 2
1. fan cooled up to 500cc with single carb and single exh.
2. free air up to 340cc with dual carbs and single exh.

class 3
1. free air up to 500cc with dual carbs and single exh.
2. fan cooled up to 500cc with dual carbs and single exh.
3. liquid cooled up to 340cc
4. free air up to 340cc with dual carbs and dual exh.

class 4
1. liquid cooled up to 500cc with single exh.
2. free air up to 500cc with dual carbs and dual exh
3. fan cooled up to 500cc with dual carbs and dual exh.

class 5 open

Looks like my jdx is gonna be running in the OPEN class- looks like i got some tweaking and testing do before Oct.

[Matt]

that does make pretty good sense, that's what I'm curious about with a bogie wheel sled and the weight transfer it seems as you start to accelerate the rear idlers (on a jdx chassis) would squat the most then going from the rear forward each set of bogie's would have decreasing pressure on them, as the front of the sled lifted up, it seemes like a bogie wheel style sled would have an advantage over a slide rail style susp. because on acceleration if the susp. isn't set up properly then when the skis lift the front of the track lifts off the ground and the only part of the track that is getting traction would be a smaller surface area from the rear idlers forward, while a bogie wheels would keep the track parallel to the ground it seems

I guess you're on the right track, but if you're making enough power (and it would have to be a lot) to get the front of the track coming up at launch with bogies, there isn't much you can do about it. You would have more ability to tune it with a good slide suspension (a better one then the JDX style).

[liquidatorkid]

that the only thing is if i plan on using the full rubber track thats in the jdx8 chassis, from a jdx4, i would hve to have some sort of bogie wheels on it with all rubber with no track windows and metal clips would creat alot of friction and damage the track, im thinking sbout building thats light, has bogies ( the lighter plastic smaller ones that you see on newer style sleds along the front of the slide rails, a cross between a set up of a texas insterments rear skid used in the thunder jets, and the pararail susp. found in a scorpion whip i belive but made to fit into a jdx tunnel, its one of those things you have to experiment with but i think im gonna try that susp. proto type i drew up and see how well it works(maybe not hav as many bogies wheels but @ the same time, the more wheels the easier it shouldd role. never know till you try, like today its pretty east to pul on the front bumper of the jdx and the drive train rolls over rally smooth and easy.

i doubt there will be any jd facroy secrete's allowed to be given out by anyone whick is fine i dont exspect them to, i think i can figure this out

all the proto sleds liek the one with the 76? hood that ed kruel raced against the alloute super and ext didnt they all have to be destroyed after testing?

[sledder670]

my coworker use to grass drag a 98 srx a former bender grass dragging sled. Ran it with no hyfax with lots of axels and wheels under it. The fast sleds do not pull the skis off the ground anymore because of the horsepower, they need the picks in the ground the best they can as well as aerodynamics. On my 91 skidoo mach 1X which was skidoos factory grass dragger it came 8 idler wheels and 4 on the rear axel and will hold the skis 2 inches of the ground till 90mph on ice. But i also found after the hole shot on it if i got the front end down at about 125' I would get 2-3 more mph in a 900' ice drag. So i would imaging there is a horsepower range where it is better to have them off the ground to reduce friction and not loose to much traction or you have so much horsepower where you cant afford to spin the track at all. It is a big clutching and gearing set up. I have watched some guys regear and clutch there sled after every race.

[jdxrobin]

I just read a short article from 2008 by snogoer (didn't know they were still around...heres the link http://www.snowgoer.com/output.cfm?id=1815751) on grass drag set-up, and they mentioned the goal is to keep the skis 1-2" off the ground the whole 500 feet. Sounds logical as the frontal area is much smaller when the sled is down than up and it eliminates the drag from the skis. They also recommended removing all the lubes from the bearings and the chaincase to minimize drag.
I happen to work with a guy that has never done grass drags, but he has built twin tracker racing sleds and he said it is common to use transmission fluid for lube in the bearings because of the friction in the grease and lube.
Found somewhere else that they run on the rear axle large rear wheels because not only does it allow the sled geometry to be such that the skis will be 1-2" off the ground during the run, but it also lifts the track off of the slides when used with the extra wheels and axles.
This is a good thread...I think if we keep talking we may come up with a number of items that will push us in the right direction

[Cabindweller]

I Know a local retired fellow, Ritchard Hoveland who used to ice drag both a 295/S and a JDX8 in the end he did better with the 8X but he says that the 295/S was a very competitive sled. I stopped in and had a visit with him a two years ago after hearing that he used to race John Deeres. His face lit up when I asked him about racing JD snowmobiles. He even asked me into his den to show me is plaqs and trophies from his racing days. I will have to visit him again and see what advice or tips he has to offer. He told me that at one point his son rolled the 295/S riding around the house and wrecked it pretty good. They redid the thing and painted it black. Last year a black 295/S came up for sale on Craigs list up in the Hayward WI area. It was in a package deal with a JD 300 if I remember right. I am not sure but I think a board member from Southern MN bought them. I will allways wonder if it was the one that Ritchard Drag raced. Another thing to note, They took the aluminum Skis off the 295/S and put them on the JDX8. So there should be a JDX8 floting around here with a set of aluninum skis on it.
Jerry

[Wildfire II]

Liqkid You have a message!!

[Horicon Joe]

I posted some of these pictures back in 2009 when I bought this sled. I bought it from Lee Hardesty before he died about a year later. As you all know he was the snowmobile engine designer for Deere. I have never seen another JD survivor drag sled before this. It is a JDX 8 with a kec 440/5 engine with dual carbs. It also has a twist throttle and pre production 295/s aluminum skis. Also has a 295/s factory belly tank made for the race team sleds. Lee told me he never lost a race with it as he was racing in Iowa. I would like to give it a try at a grass drag some day .....
you guys have spurred my interest.

Joe

[Horicon Joe]

more

[Cabindweller]

Very Cool Sled. Those are some interesting carb adapters on the JDX8. I have never seen that type before. Looks like a points setup?

Jerry

[JD600]

The expansion chamber looks to be something pre production as well. I don't recall either the 295/s or the 800/X8 pipes having all of those welds on them? Could this have been one of the pipes that was used as a hand made model for the production pipes?

DE

[jdxrobin]

Joe...
That's what I'm talking about stripped of all the unnecessary stuff and ready to rock!
Did he say why the twist grip throttle?
By the way, I went to the Wahl bros page and looked at some of the suspensions ($$$)...many idler wheels.
They also have the ISR year (rule) book for 8 bucks...I gotta do it!

[Matt]

The expansion chamber looks to be something pre production as well. I don't recall either the 295/s or the 800/X8 pipes having all of those welds on them? Could this have been one of the pipes that was used as a hand made model for the production pipes?

DE

Definitely, and also check out the all aluminum engine mount.