Cracked tunnel behind bearing carrirer

[Gman25]

Hello all

Wanted to post on my 2018 ltx cracked tunnel.
Last year i installed a new axle as well as a axle wedge and torque to spec. Put 2500 km on last season and upon my yearly tear down and inspection found this.
Obviously very disappointing but glad i found it before it all let go.
Run your sleds with track in air and watch for any movement in your caliper/ rotor if your three mounting bolts are tight then you have a problem.
I had a plate made from 90 thou aluminum and had my aircraft mechanic buddy install it with proper rivets. Note his design with plate covering large caliper piston hole. Arctic cat should not have had two large holes so close together without a doubler or tripler added
Any engineer will comment on this inadequate design
Hope this helps some of you!

 

[Gman25]

Hello all

Wanted to post on my 2018 ltx cracked tunnel.
Last year i installed a new axle as well as a axle wedge and torque to spec. Put 2500 km on last season and upon my yearly tear down and inspection found this.
Obviously very disappointing but glad i found it before it all let go.
Run your sleds with track in air and watch for any movement in your caliper/ rotor if your three mounting bolts are tight then you have a problem.
I had a plate made from 90 thou aluminum and had my aircraft mechanic buddy install it with proper rivets. Note his design with plate covering large caliper piston hole. Arctic cat should not have had two large holes so close together without a doubler or tripler added
Any engineer will comment on this inadequate design
Hope this helps some of you!

 

[Gman25]

 

[1nc 2000]

Hopefully your track won't rub on all the fasteners. Not a lot of room up there adding all that. He should have installed counter sunk cherries instead of button heads.
.090" is plenty thick plus the rivet heads.

 

[DMCTurbo]

Mine cracked after last season. 17000km on sled. I too ran the wedge. Installed as per Mike Knapps method. I'm no longer running the wedge. My thought is the wedge caused the damage. I believe there's a reason the engineers designed it this way, so there's flex so things can move. I welded and turned down my shaft to a tighter tolerance. We'll see after the season how it holds up.



This is my opinion. Take it for what it's worth.

 

[NYTurbo]

Mine cracked after last season. 17000km on sled. I too ran the wedge. Installed as per Mike Knapps method. I'm no longer running the wedge. My thought is the wedge caused the damage. I believe there's a reason the engineers designed it this way, so there's flex so things can move. I welded and turned down my shaft to a tighter tolerance. We'll see after the season how it holds up.



This is my opinion. Take it for what it's worth.

Yeah. Your probably right.

 

[1nc 2000]

The Yamaha rep said; the sled is designed for 200hp not 300hp.
Yep I have seen indy 500 crack the tunnel from bearing wobble in the 90's.

 

[hibshman25]

Hello all

Wanted to post on my 2018 ltx cracked tunnel.
Last year i installed a new axle as well as a axle wedge and torque to spec. Put 2500 km on last season and upon my yearly tear down and inspection found this.
Obviously very disappointing but glad i found it before it all let go.
Run your sleds with track in air and watch for any movement in your caliper/ rotor if your three mounting bolts are tight then you have a problem.
I had a plate made from 90 thou aluminum and had my aircraft mechanic buddy install it with proper rivets. Note his design with plate covering large caliper piston hole. Arctic cat should not have had two large holes so close together without a doubler or tripler added
Any engineer will comment on this inadequate design
Hope this helps some of you!

How many miles on the sled?

Was there tunnel/caliper movement as driveshaft spun?

 

[Motorhead]

I saw first hand what a caliper wobble looks like, from locking the bearing while not setting it perfect! I was just idling it enough to spin the track while on a lift!
I can just imagine how much stress it would cause at high speeds for a full season!

So glad I caught it before running it that way!

 

[stgdz]

does anyone have a video of what this tunnel flexing bearing wobble is like?

 

[Motorhead]

does anyone have a video of what this tunnel flexing bearing wobble is like?

I took a couple from my iPhone to better explain to the installer what was happening!

PM me your number or email, I will send them! Not sure how to place a video on here!

 

[KnappAttack]

If the bearing is cocked on the shaft at all it will wobble and crack. Just common sense.


Use a dial indicator to verify NO WOBBLE. It you rotate a bunch upon install of the wedge it will nomilize the bearing to the shaft. Dial indicate to verify no wobble. If you do this properly the chassis will never crack, if not done properly, it will crack from wobble. I’ve got sleds with over thousands of miles and no cracks and no spinning bearings. If you fiex metal or alum enough times it’s guaranteed to crack. Just because you can’t see a wobble doesn’t mean it’s not flexing. Use an indicator. Many people have a dealer mechanic putting the wedge in and they don’t get how critical it is to get the wedge installed PERFECT.

They don’t crack when down properly. Even running 300 +HP

Had Cat engineered it properly from the start we wouldn’t even be talking about this. The problem is people don’t understand how to install the wedge properly and how critical it is to get perfect. Spin the track a lot while tightning and torquing. It will not wobble if done correctly. PERIOD. IF IT DOESNT WOBBLE, and that menns ZERO RUN OUT on the dial indicator. It will NEVER CRACK. If you need a video or instructions on how to do this install, it’s obvious you shouldn’t be messing with it yourself. It’s common sense how it works.

 

[Gman25]

How many miles on the sled?

Was there tunnel/caliper movement as driveshaft spun?

Sled has 11,000 miles on it but last season i installed a new drice axle and for the first time since i owned sled put a wedge in.
I tear my 3 winders doen every fall for a full preseason check and this is what i found. I had only run sled about 1800 miles over last season and thats when the crack formed as it was not there last year.
I just read where a guy installed the wedge tightened i bit more than finger tight and ran sled on stand then another tightening sequence and ran sled again. He did this 4-5 times until wedge was at proper torque. I will try this method upon reassembly.
I should have shot a video of caliper wobble it was going up and down more than a 1/8 of inch when spinning track on stand due to there being not much of tunnel left to support carriere.

If the bearing is cocked on the shaft at all it will wobble and crack. Just common sense.


Use a dial indicator to verify NO WOBBLE. It you rotate a bunch upon install of the wedge it will nomilize the bearing to the shaft. Dial indicate to verify no wobble. If you do this properly the chassis will never crack, if not done properly, it will crack from wobble. I’ve got sleds with over thousands of miles and no cracks and no spinning bearings. If you fiex metal or alum enough times it’s guaranteed to crack. Just because you can’t see a wobble doesn’t mean it’s not flexing. Use an indicator. Many people have a dealer mechanic putting the wedge in and they don’t get how critical it is to get the wedge installed PERFECT.

They don’t crack when down properly. Even running 300 +HP

Had Cat engineered it properly from the start we wouldn’t even be talking about this. The problem is people don’t understand how to install the wedge properly and how critical it is to get perfect. Spin the track a lot while tightning and torquing. It will not wobble if done correctly. PERIOD. IF IT DOESNT WOBBLE, and that menns ZERO RUN OUT on the dial indicator. It will NEVER CRACK. If you need a video or instructions on how to do this install, it’s obvious you shouldn’t be messing with it yourself. It’s common sense how it works.

as you said many dealers get it wrong, i have installed many of these and this is the first one with a problem.
I have also welded up axles and turned them down to match brg i prefer this method as i have had zero problems.
I am using bdx axles

 

[KnappAttack]

Cracks will never happen if the bearing/caliper housing has zero wobble. That’s the bottom line. I don’t care how many miles it has.

Obviously the caliper was wobbling and broke the chassis.

 

[Gman25]

Cracks will never happen if the bearing/caliper housing has zero wobble. That’s the bottom line. I don’t care how many miles it has.

Obviously the caliper was wobbling and broke the chassis.

You are corect the caliper was moving up and down and cracked the chassis it is now repaired stronger than original and without the secondary hole drilled through tunnel.
I showed cats design to a senior rngineer at bmw and he was disgusted by cats poor desin and engineer, i then showed him the rest of cats poor engineering and he could not believe their engineering team has not been fired for putting out the same crap year after year and not fixing any of it