Need skid mounting advice

[Ding]

I am attempting to retrofit a Nytro XTX skid in a Viper. I have an accurate measurement for the CTC for the 2 mount points, but am struggling with the setback and attitude of the skid.

What do you guys that fit a lot of skids do?

The best I can come up with is . . .

• Take 2 pieces of flat stock and drill holes to match the front and rear mount CTC.
• Mount the flat stock on both sides of the skid to simulate the mounted geometry.
• With the drive axle and track mounted in the sled, position the skid so that track tension, ride height, and attitude will work.

What all am I looking for when deciding proper orientation and setback?

Please comment with any useful advice that you have.

 

[Ding]

Please help if you can . . .

 

[snowdad4]

what works best for me is to use the measurements from the donor sled. i start with the drive shaft to front arm center to center. use the top of the tunnel to measure from for the height dimension. center to center from front arm to rear scissor. check all measures and lay it out inside the tunnel. i use aluminum for backing plates, usually make my own drop brackets. way i see it, if the geometry was correct and worked in the original, same mounting points will work on recipient. is this what you were asking?

 

[Ding]

Thanks for the reply.

Yes, I have the basics down as I have done a few skid swaps. However I am no pro and this is a bit of a challenge as the 2 sleds are significantly different. The sled came out of the FX chassis of the 4-stroke Nytro XTX, and I am putting it into the Pro-Action chassis of the Mtn Viper. The tunnel designs are quite different, so I am having difficulty getting the best orientation on the first try.

Here is my current plan, please critique it as you see fit . . .

1. Mount the old skid in the sled and take measurements at the front and back of the tunnel without any load on it (Measure to bottom of rails)
2. Tie the 2 mount points of the new skid together with flat stock to insure correct geometry.
3. Place the new skid in the tunnel and lower the sled until the same height as above is achieved.
4. Mark the tunnel for the mount points on a horizontal plane (relative to the rails).
5. Install the drivers and track.
6. Position the skid in the track and pull rearward along horizontal lines made previously until the slack in the track is removed.
7. Measure the front mount to axle and compare with original sled.
8. As long as the measurement in 7 above hasn't changed too much Mount It!!!
9. If much different, I am lost . . .

One outstanding question left to be answered . . .

How much slack in the track tension does changing from 9-tooth to 8-tooth drivers cause ??? (2.52 pitch)

 

[modsledr]

My advice would be to make it adjustable, with optional mounting holes. 1" up, down, front, back...(if you need to move it front or back, move both the front and rear at the same time to maintain the c-c).

If you look at a lot of older aftermarket skids, the drop brackets look like swiss cheese for adjustability. Since the 2 tunnels and sleds are so different, its doubtful you'll nail it on the first attempt, so if you design adjustability into your install, you'll make your life easier in the long run.

 

[Ding]

Here are some pics with the XTX skid positioned as close as I can get it to the where the Mtn Viper skid was in the bottom holes . . .

 

[modsledr]

Do you still have the old skid intact? If so, place the 2 side by side with all of the shocks/springs installed to compare the fully extended dimensions. This may give you some direction as to the differences in mounting locations.

 

[Ding]

What would you guys do for front and rear brackets?

1. Machine them out of aluminum - worried about strength.
2. Machine them out of Stainless Steel - worried about reacting with Aluminum.
3. Machine out of Steel - worried about rusting.
4. Use Apex Mtn plates - don't know if they fit, Nytros do not fit.

Anybody else have any ideas?

 

[Ding]

Yes, I had them side by side on the table, and they are similar except the XTX mount locaions are about 5 inches or so farther forward.

As a result of my comparisons: To get the same rail angle at full extension relative to the skis, the XTX skid must be mounted 1 inch lower. This would of course change the ski pressure, but not likely a lot.

I think I am going to start there and do as you suggested with options to move it around. I do have to mount the skid 3/4 inch to the rear in order to miss the steering gate with the front mount. I don't expect this to change much either, what do you think? This will of course tighten up the track, but I am hoping that going from 9-tooth to 8-tooth drivers it will still fit.

 

[Motley Doo]

Find some alum. sign material, the stuff is tempered, so it is super strong, but is pretty light. I've been using it as drop brackets for a year and have no issues.