Arctic Cat Forum banner

41 - 60 of 60 Posts

·
Registered
Joined
·
40 Posts
Discussion Starter #41
Working on setting the ride height. The Cat manual states the engine plate should be at zero degrees fore and aft with the A-arms as close to parallel with the ground as practical. After completing the AGLT mod I noticed that when the front arm mount was in the stock 121" hole the front of the rail had an unacceptable positive angle to the ground (I converted from 121 to 136). This would seem to have the net effect of reducing ski pressure since the rails are angled up under static conditions.
My solution was to drop the front arm down to the next hole. The tunnel was not drilled but the hole was drilled in the mount plate. This dropped the rails back down to nearly flat which would seem to be the desired configuration. This necessitated the addition off an anti-stab kit and slight trimming of the front rail tip. Below are the results.
So, in a nutshell, engine plate zero degrees, A-arms parallel (mostly) and rails flat on the ground. Check my logic and let me know if you disagree.

Here is a great slow-mo video of a Thundercat accelerating. I like this video because you can visualize what motions the suspension goes through under acceleration. You can also see how the TSL's drives the front of the rails down to put as much track on the ground under acceleration to maximize traction.

 

Attachments

·
Registered
Joined
·
9,743 Posts
Working on setting the ride height. The Cat manual states the engine plate should be at zero degrees fore and aft with the A-arms as close to parallel with the ground as practical. After completing the AGLT mod I noticed that when the front arm mount was in the stock 121" hole the front of the rail had an unacceptable positive angle to the ground (I converted from 121 to 136). This would seem to have the net effect of reducing ski pressure since the rails are angled up under static conditions.
My solution was to drop the front arm down to the next hole. The tunnel was not drilled but the hole was drilled in the mount plate. This dropped the rails back down to nearly flat which would seem to be the desired configuration. This necessitated the addition off an anti-stab kit and slight trimming of the front rail tip. Below are the results.
So, in a nutshell, engine plate zero degrees, A-arms parallel (mostly) and rails flat on the ground. Check my logic and let me know if you disagree.

Here is a great slow-mo video of a Thundercat accelerating. I like this video because you can visualize what motions the suspension goes through under acceleration. You can also see how the TSL's drives the front of the rails down to put as much track on the ground under acceleration to maximize traction.

Any more progress? Kinda looking forward to it!!!
 

·
Registered
Joined
·
40 Posts
Discussion Starter #43
So I have been working on some of the more mundane item. Here is something cool. I was held up because the original belly pan was annihilated. I searched high and low and found a brand new one. Interestinlgy it is the Arctic Cat master belly pan for making the molds.
 

Attachments

·
Registered
Joined
·
9,743 Posts
So I have been working on some of the more mundane item. Here is something cool. I was held up because the original belly pan was annihilated. I searched high and low and found a brand new one. Interestinlgy it is the Arctic Cat master belly pan for making the molds.
That will be one damn nice sled when your done with it for sure!!
 

·
Registered
Joined
·
40 Posts
Discussion Starter #45
A close examination of the driven shaft gear shows some fretting corrosion and macropitting of the gear teeth on the drive side. This I would imagine is due to the inherent misalignment of the chain links as they are initially taken up by the gear not to mention the chain slapping the tooth during hard accelerations. The other side is still in serviceable condition. Since the gear teeth profile are symmetrical I see no issue in flipping it around and running it. I'll snatch a new one on ebay or a swap meet for a spare.
 

Attachments

·
Registered
Joined
·
40 Posts
Discussion Starter #46
Working on the chain case, jackshaft, bearings...etc. For the brake disc I went over the friction surface with a medium 2" scuff pad on a die grinder. The hub is repainted with hi-temp paint. For the jackshaft a coat of zincrom primer to control corrosion and then two top coats of black epoxy. I tried this "gold cad" paint to replicate the look of the yellow chromate coating on the bearing retainer. To me it just looks like gold paint. It says your supposed to mix it with a green or red zinc paint but who cares? A new chain for good measure.
This is where I go off on a tangent. This sled new was $10,000 dollars and the best they could do is a bunch of combine bearings. Yeah they are durable and take a lot of abuse but the power path from the PTO side changes directions four different times at 90 degree angles before it hits the drive shaft. One of the fundamentals of drivetrain design is to remove bearings wherever you can. Each bearing presents a chance for misalignment and losses. 4 bearing and a chain in the power path...really!
Ok, I'm stepping off my soapbox now...moving along.
 

Attachments

·
Registered
Joined
·
9,743 Posts
Working on the chain case, jackshaft, bearings...etc. For the brake disc I went over the friction surface with a medium 2" scuff pad on a die grinder. The hub is repainted with hi-temp paint. For the jackshaft a coat of zincrom primer to control corrosion and then two top coats of black epoxy. I tried this "gold cad" paint to replicate the look of the yellow chromate coating on the bearing retainer. To me it just looks like gold paint. It says your supposed to mix it with a green or red zinc paint but who cares? A new chain for good measure.
This is where I go off on a tangent. This sled new was $10,000 dollars and the best they could do is a bunch of combine bearings. Yeah they are durable and take a lot of abuse but the power path from the PTO side changes directions four different times at 90 degree angles before it hits the drive shaft. One of the fundamentals of drivetrain design is to remove bearings wherever you can. Each bearing presents a chance for misalignment and losses. 4 bearing and a chain in the power path...really!
Ok, I'm stepping off my soapbox now...moving along.
What gearing is that. 26/39?
 

·
Registered
Joined
·
40 Posts
Discussion Starter #48
What gearing is that. 26/39?
It's the stock 24/39 or 1.62 ratio. This would give me a theoretical MPH of around 96 at the stock clutch shiftout at 8200rpm. I switched to an 8 tooth non-ratcheting driver. I am more intersted in elbow staightening than top speed so I will probably change the ratio. I don't really want to spin the motor any higher so I will probably stick close to the stock clutching and go up to a 42 or 44 tooth driveshaft sprocket. That should put my MPH at 1:1 on the clutches in the high 80's.
 

·
Registered
Joined
·
9,743 Posts
It's the stock 24/39 or 1.62 ratio. This would give me a theoretical MPH of around 96 at the stock clutch shiftout at 8200rpm. I switched to an 8 tooth non-ratcheting driver. I am more intersted in elbow staightening than top speed so I will probably change the ratio. I don't really want to spin the motor any higher so I will probably stick close to the stock clutching and go up to a 42 or 44 tooth driveshaft sprocket. That should put my MPH at 1:1 on the clutches in the high 80's.
The problem with that is that when your running 40-60 MPH, there isn't much left with that gearing and 8 tooth drivers. I was originally 24/39-8T then switched it all around numerous times to many different gear and clutch combos. Just last year after serious testing I ended up with 26/35-8T Yes, thats correct. It pulls harder than the gearing your speaking of. The Proof was my other sled finally lost to my geared zrt with that gearing for the first time when ran side by side. The problem is while trail riding you are at MPH, not a dead stop, and when stabbing the throttle there isn't much left. Just last year I geared my little zrt 600 at 20/39 and is great (IF) it hooks up from a dead stop, but going 60 then stabbing it, forget it, nothing there to get out of its own way. Big block triples like yours are different, you need to grunt the engine more. Load the motor. Been there done that. I know it sounds bass ackwards, but its not. If you do some searches on HCS forum you will see what I mean. I know this is a trail sled. Don't take my word for it, try it. I bet your arms are straightened out more with the higher gearing and clutching. Here are some pics of my clutching parts but not all, and records just to show how much I really do experiment.
The 98 pipes are very hard to beat with aftermarket ones. They should turn 83-8400 rpms.
 

Attachments

·
Registered
Joined
·
9,743 Posts
The problem with that is that when your running 40-60 MPH, there isn't much left with that gearing and 8 tooth drivers. I was originally 24/39-8T then switched it all around numerous times to many different gear and clutch combos. Just last year after serious testing I ended up with 26/35-8T Yes, thats correct. It pulls harder than the gearing your speaking of. The Proof was my other sled finally lost to my geared zrt with that gearing for the first time when ran side by side. The problem is while trail riding you are at MPH, not a dead stop, and when stabbing the throttle there isn't much left. Just last year I geared my little zrt 600 at 20/39 and is great (IF) it hooks up from a dead stop, but going 60 then stabbing it, forget it, nothing there to get out of its own way. Big block triples like yours are different, you need to grunt the engine more. Load the motor. Been there done that. I know it sounds bass ackwards, but its not. If you do some searches on HCS forum you will see what I mean. I know this is a trail sled. Don't take my word for it, try it. I bet your arms are straightened out more with the higher gearing and clutching. Here are some pics of my clutching parts but not all, and records just to show how much I really do experiment.
The 98 pipes are very hard to beat with aftermarket ones. They should turn 83-8400 rpms.
Sixpack in post #3 hit the nail right on the head. I experienced the same thing. There are alot of factors that go into that, I am sure some aren't mentioned.
You will want to gear higher than your planning. Your call. Just trying to help ya. Try it and see.

7 tooth drivers? - HCS Snowmobile Forums

One thing not mentioned is while being geared to say roughly 130 MPH your belt will remain lower in the primary (which has more leverage) to grunt the mass weight including yourself on board to quicker acceleration.
 

·
Registered
Joined
·
40 Posts
Discussion Starter #51
We have a saying in the profession, "if you don't have data, all you have is an opinion" and it it looks like you have a ton of data.

Basically I'm just going to set it up like the 1000 Mountain Cats.
 

·
Registered
Joined
·
9,743 Posts
We have a saying in the profession, "if you don't have data, all you have is an opinion" and it it looks like you have a ton of data.

Basically I'm just going to set it up like the 1000 Mountain Cats.
Your call.
 

·
Registered
Joined
·
9,743 Posts
Your call.
Don't forget to change your speedo drive adapter to the mountain cat type or it will read way high on the speedo.
 

·
Registered
Joined
·
196 Posts
Looking great! What are your plans for the tunnel extension? What did you use to clean up the aluminum skid rails? I have a 2006 Crossfire 700 that I plan on selling this year and want to clean up the dull skid frame rails.
 

·
Registered
Joined
·
40 Posts
Discussion Starter #55
Looking great! What are your plans for the tunnel extension? What did you use to clean up the aluminum skid rails? I have a 2006 Crossfire 700 that I plan on selling this year and want to clean up the dull skid frame rails.
The skid came off a 2001 Mountain Cat and the rails were powder coated green. To strip the powder coating required a methylene chloride paint stripper several of which are available at the local hardware store. After stripping the powder coat I went over the rails first with a medium 2" (red) finishing pad to pull up any stubborn areas then moved to 2" (blue) finishing pad to blend the swirls from the red pads. Then if I remember I went over with 600 grit and then 1000 grit wet. Once the rails had a unifrom dull finish I mountain a 4" buffing pad to a drill and started with white rouge and then finished with blue plastic. Here are some before and afters. Was it worth all the time and effort, I don't know. The rails are alomost 20 years old and and had been ridden hard. Some may think it amounts to polishing a turd but I am ok with the results.
As for the tunnel extension I am going to buy some sheet from McMaster and bend it up in the HF brake.
 

Attachments

·
Registered
Joined
·
40 Posts
Discussion Starter #57
Don't forget to change your speedo drive adapter to the mountain cat type or it will read way high on the speedo.
Awhile back I found a new one on ebay and snatched it. Sometimes it seems like dropping funds on a 20 year old sled is not the most fiscally sensible thing to do. On the other hand it's no different that a guy rebuilding an LS6 Chevelle or Boss 429. Thundercats in my opinion are the Hemi Cuda of snowmobiles. Just a great big middle finger to all the pretenders.
Eventully I will collect all the mid-late 90's muscle sleds. Already have 94 and 98 Thundercats and 1989 Indy 650, next is a Polaris 800 Storm, Mach Z and maybe a Vmax 4.
Here are some pics of my 94.
 

Attachments

·
Registered
Joined
·
40 Posts
Discussion Starter #58
Kitty's got new shoes.

Up next in the staging lanes, open heart surgery. For anyone following along I plan on documenting the full tear down and rebuild...for better or worse. All I know is it ran before disassembly and was 130 psi in all three holes. Maybe we can avoid costly boring/plating and clean up the holes and pop some new slugs in her (yeah right).

🤟😝
 

Attachments

·
Registered
Joined
·
9,743 Posts
Check ring end gap. You may be fine with those readings. If you think there is more than 2500-3000 miles on pistons, replace. Do you plan on doing the balance shaft oiling mod?
 

·
Registered
Joined
·
9,743 Posts
Awhile back I found a new one on ebay and snatched it. Sometimes it seems like dropping funds on a 20 year old sled is not the most fiscally sensible thing to do. On the other hand it's no different that a guy rebuilding an LS6 Chevelle or Boss 429. Thundercats in my opinion are the Hemi Cuda of snowmobiles. Just a great big middle finger to all the pretenders.
Eventully I will collect all the mid-late 90's muscle sleds. Already have 94 and 98 Thundercats and 1989 Indy 650, next is a Polaris 800 Storm, Mach Z and maybe a Vmax 4.
Here are some pics of my 94.
That T-cat on the trailer looks fine my man!!
 
41 - 60 of 60 Posts
About this Discussion
59 Replies
9 Participants
tcat446
Arctic Cat Forum
Arctic Cat forum is a community to discuss Arctic Cat 400, 440, 500, 650, snowmobiles, sleds, ATV's and more. Join the fun!
Full Forum Listing
Top