Thumping in loose snow

[Hoagie989]

Last year i bought an 07 rtx apex. The only concern that i have is when im in loose or deeper powder and i give it the throttle, I'll get like a thumping or clunking that comes from either underneath the seat or from the engine bay. Its not consecutive. Its a hit or miss. Sometimes itll thump other times it wont. Sometimes itll be 2 thumps, other times only 1. It only does it in powder. If im on hard pack or ice it doesnt do it. Just wana know if i should be concerned and where to start looking if i should be.

 

[RobX-1]

How is your drive axle bearing; the one underneath the clutches? When was the last time it was inspected/replaced?

 

[sideshowBob]

Sounds like track ratcheting.
Possible causes:
- track too loose....set to OEM specs
-broken suspension front scissor[W] arm....not uncommon on older Apexs
-worn or damaged track drives
-drive axle bearing destroyed from wear as RobX-1 said

 

[Hoagie989]

How is your drive axle bearing; the one underneath the clutches? When was the last time it was inspected/replaced?

No idea. Like i said didnt know where to start.

 

[Hoagie989]

No idea. Like i said didnt know where to start. I came here for ideas and and to get pointed in the right direction so thank you for the help!

 

[Hoagie989]

Its a clean sled for the most part. The previous owner had a whole portfolio on receipts and service records. The last service on it was 2 months before i bought it last year

 

[RobX-1]

The drive axle bearing was just the first thing I thought of after reading your desciprtion but @sideshowBob does list some other possibilities so best thing would be to get the rear of the sled elevated to inspect and start there.

 

[earthling]

sounds suspension related. If it was the track, it shouldn't ratchet as much in powder but if it is the track, you should also feel it is a loss in drive. The suspension unloading you would hear whenever the skid is not in solid contact with the ground. The track is easiest to diagnose. Lift the back of the sled up off the ground on a stand and you can see and measure the track sag. While the rear is in the air, reach in and grab the suspension components, you should not feel significant play anywhere. inspect the w arm, they are known to fail.

 

[Hoagie989]

sounds suspension related. If it was the track, it shouldn't ratchet as much in powder but if it is the track, you should also feel it is a loss in drive. The suspension unloading you would hear whenever the skid is not in solid contact with the ground. The track is easiest to diagnose. Lift the back of the sled up off the ground on a stand and you can see and measure the track sag. While the rear is in the air, reach in and grab the suspension components, you should not feel significant play anywhere. inspect the w arm, they are known to fail.

How much track slack am i looking for?

 

[RobX-1]

 

[RobX-1]

FYI, become a VIP on the site and one of the membership perks is access to the service manual for your Apex.

 

[RobX-1]

LOL, just noticed my VIP membership had recently lasped but that was immediately remedied.

 

[Stubbs]

‘07 Ape RTX had the CK skid…..as they collapse this skid loses track tension, very important to run it at Yammy spec. When you’re in deep snow and grab a handful the rear arm collapses quite a ways depending on how your transfer is set on the control rods. The high load of the deep snow combined with the collapsing suspension rear arm = track ratcheting with this skid. Been there, done that.