Nikolai
TY 4 Stroke God
Pressure test held for 24 hrs at 20 lbs.
Added a matching 1” tube gusset to the other side(that has 2 coolant tubes) to help brace the running board tube since it has a big hole in the top for coolant. Wanted to make the gusset longer so it supported further back but my OCD got the best of me and it ended up the same.
Going to weld up the motor mounts next. I have some 1/8” NPT bungs and plugs coming in the mail to weld in 2 low point drains so I can easily drain the coolant from the frame tubes if needed. Once those get here and welded in then it will go back into the jig.
Added a matching 1” tube gusset to the other side(that has 2 coolant tubes) to help brace the running board tube since it has a big hole in the top for coolant. Wanted to make the gusset longer so it supported further back but my OCD got the best of me and it ended up the same.
Going to weld up the motor mounts next. I have some 1/8” NPT bungs and plugs coming in the mail to weld in 2 low point drains so I can easily drain the coolant from the frame tubes if needed. Once those get here and welded in then it will go back into the jig.
kinger
VIP Member
So clean!
Nikolai
TY 4 Stroke God
Thanks.
I’ve been doing some reading about stress relieving the welds and everything I’ve been able to research states that 4130 tube with a wall thickness less than 0.125 does not need post weld heat treatment if er70s-2 filler is used and the tubing is room temp when welded. Only way to do DIY would be with an O/A torch and that can make it worse if you get it too hot so I’m not going to worry about it. If I get any cracks over time I will just fix them.
I’ve been doing some reading about stress relieving the welds and everything I’ve been able to research states that 4130 tube with a wall thickness less than 0.125 does not need post weld heat treatment if er70s-2 filler is used and the tubing is room temp when welded. Only way to do DIY would be with an O/A torch and that can make it worse if you get it too hot so I’m not going to worry about it. If I get any cracks over time I will just fix them.
kinger
VIP Member
I thought you were safe with chromo, I think you will be ok. Maybe add some flat plate at the junctions to spread out the load over more of the tube. Otherwise it will tear next to the weld. We weld thin wall tube for floating dock systems and had to do this to avoid cracks next to the weld about 3-4 years later. Works good. On a 2” angle we had to add about 2 more inches of flate plate on to the tubes and that was enough to cure it.
Nikolai
TY 4 Stroke God
Need some help with motor mount bolts and coming up with something lighter. Factory bolts are M12 and shortest bolt that will work is 70mm. M12-1.25 x 70mm Titanium bolts are $33 ea for good quality ones plus $9 ea for nuts. I’m not spending $168 on bolts. I have a few options.
1. Drill out the 12mm bolts I have now to reduce the weight. Weight loss will be minimal. Bolts are only in tension and 12mm seems way overkill to hold a motor in place inside 8 steel tabs so I don’t foresee any strength issues.
2. Drill out the motor mount sleeves an additional 1/32 from 0.48 to 0.5” ID then drill out my tabs and use 1/2 chromoly tubular bolts. These are only $9 ea, plenty strong and should be quite a bit lighter.
3. Leave the motor mount sleeves alone and make sleeves from chromoly tube to reduce ID from 0.48 to .0375 and use 3/8 bolts.
I would prefer option 2 but I’m not sure how easily the motor mount sleeves will drill out using a 1/2 bit in a drill.
1. Drill out the 12mm bolts I have now to reduce the weight. Weight loss will be minimal. Bolts are only in tension and 12mm seems way overkill to hold a motor in place inside 8 steel tabs so I don’t foresee any strength issues.
2. Drill out the motor mount sleeves an additional 1/32 from 0.48 to 0.5” ID then drill out my tabs and use 1/2 chromoly tubular bolts. These are only $9 ea, plenty strong and should be quite a bit lighter.
Tubular Chromoly Bolts
www.brmotorsports.com
3. Leave the motor mount sleeves alone and make sleeves from chromoly tube to reduce ID from 0.48 to .0375 and use 3/8 bolts.
I would prefer option 2 but I’m not sure how easily the motor mount sleeves will drill out using a 1/2 bit in a drill.
sxr70001
Lifetime Member
- Joined
- Dec 4, 2010
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- 1,120
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- Michigan
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- USA
- Snowmobile
- Sidewinder LTX SE
SR Viper RTX SE
If you have access to a lathe if would be easier to drill out bolts accurately.
Nikolai
TY 4 Stroke God
I do have a mini lathe and that’s what I did tonight. Didn’t feel like I could drill out the motor mounts and there was a good chance of screwing that up.
I had 4 brand new 10.9 m12-1.5x75 leftover bolts from a RZR project I never used.
Shortened them to 68mm which is as short as I can go for the nuts I ordered. Turned the head down, turned the flange down so it would fit in my lathe backwards, drilled a .190 hole thru it and then dished the head a little.
Before weight was 82.89 grams
After weight was 61.59 grams (0.135 lbs)
2 hrs of time wasted priceless.
I called about the 1/2 x 2.75 tubular bolts and they weighed them for me at 0.15 lbs and also an equivalent Ti bolt which was 0.10 lbs so I didn’t do to bad. Only time will tell if they’re going to hold up. They aren’t going to require much torque to keep the motor from moving.
I had 4 brand new 10.9 m12-1.5x75 leftover bolts from a RZR project I never used.
Shortened them to 68mm which is as short as I can go for the nuts I ordered. Turned the head down, turned the flange down so it would fit in my lathe backwards, drilled a .190 hole thru it and then dished the head a little.
Before weight was 82.89 grams
After weight was 61.59 grams (0.135 lbs)
2 hrs of time wasted priceless.
I called about the 1/2 x 2.75 tubular bolts and they weighed them for me at 0.15 lbs and also an equivalent Ti bolt which was 0.10 lbs so I didn’t do to bad. Only time will tell if they’re going to hold up. They aren’t going to require much torque to keep the motor from moving.
sxr70001
Lifetime Member
- Joined
- Dec 4, 2010
- Messages
- 1,120
- Location
- Michigan
- Country
- USA
- Snowmobile
- Sidewinder LTX SE
SR Viper RTX SE
They look awesome though. 
Your attention to detail is staggering. I love watching this come together, glad you are back on it again.
Your attention to detail is staggering. I love watching this come together, glad you are back on it again.
RobX-1
VIP Member
- Joined
- Apr 13, 2003
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- 2,142
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- Coldwater, OH
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- USA
- Snowmobile
- 18 50th Apex XT-X, 08 40th Apex LTX GT, 08 40th Nytro RTX, & 03 RX-1
X2!
kinger
VIP Member
I think you nailed it. I had a 3 pc idea for the bolt but too complex I like your idea.
Nikolai
TY 4 Stroke God
What’s your idea? I would like to hear it.
kinger
VIP Member
I was going to say not use a bolt but a 'nub' (the bolt cut down to like 1/2" long) that just slipped inside the bolt hole on each side that was then held in place with a connecting strap that would go over both sides to lock it in place.
Nikolai
TY 4 Stroke God
What kind a tension strap? It would need to provide fairly strong clamping force to keep the motor from rattling in the mounts.
kinger
VIP Member
I was thinking the tabs you made could have like a small pocket, or lip added that the strap would have to get pounded into to fit. Once in a small stop on the top side of the strap to ensure it didn't pop off. Your idea is better.
Nikolai
TY 4 Stroke God
I finished all 4 bolts yesterday. The drill bit I was using wasn’t very sharp so I bought a 13/64 cobalt bit and drilled them one last time so the finish inside would be good. Nuts should be here in a few days and I’ll get comparison weights to the previous setup I was using but it’s well over a pound lighter.
Still waiting on my 1/8 NPT bungs to show up in the mail so I can finish the low point drains but here’s a pic of plugs. 1/8 NPT 6061 Aluminum anodized plugs. Not even 1 gram a piece. It was the lightest drain setup I could think of.
1.93 grams for both.
Still waiting on my 1/8 NPT bungs to show up in the mail so I can finish the low point drains but here’s a pic of plugs. 1/8 NPT 6061 Aluminum anodized plugs. Not even 1 gram a piece. It was the lightest drain setup I could think of.
1.93 grams for both.
