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Discussion Starter #1
Just put new pistons and rings in. It runs great. probably 100 miles on her so far.
Painted pipes yesterday, re installed them and fired it up. Noticed engine moving more than normal. Looked at motor mount near the recoil and it's still there, not broken but the 2 bolts going into the engine arent there. One is in the belly pan, sheared off. the other is ????
Today, out comes the engine, again.
I can see the rest of the bolt, it's inside the engine.
probably have to drill it out (yeah,it's a grade 8 bolt) and more than likely have to drill it larger and tap new threaded into one of the 2 bolts holes in the engine. I'm not an expert on drilling and tapping especially in aluminum.
Any advise would be helpful. thanks.
This engine broke 3 or 4 motor mounts, all the same one, so I made one out of steel instead of the cast aluminum one that Cat sells. Now the bolts gave up.
 

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Something isn't right if you snapped grade 8 bolts off. Even the skid bolts are grade 5 stock. If there is any chance of it use a left handed bit and try to back em out with a easy out. Or if there is anything protruding you may be able to get a stud remover on it and back it out.
 

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Discussion Starter #3
There 5/16th bolts, so not the biggest in the world. I may have it tapped for 3/8 ths . Would have been nice to notice this 2 weeks ago when the engine was on the work bench.
but of course that would have been way too easy.
 

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Is your torque bumper adjusted properly? 5/16 is .3125 and 3/8 is .375 only 1/8 inch different from the rear skid bolts which I would imagine take waaaaaay more abuse.
Fact for ya tho the head is the usually the weakest point in a bolt so if it had a 1/4 plate that it was snugged up to you should have some threads sticking out.
 

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Discussion Starter #5
Torque bumper has either .060 or .080 clearance, I have the factory service manual and adjusted it by that.
The center to center and offset was perfect. This engine use to have a B/M clutch kit on it that hit very hard off the line. Figured that is what was causing the broken aluminum mount. So I beefed it up to steel. Been great for years. I have a different clutch set up that isnt as hard on everything now.
But I've added about 20 horse's to the engine and better traction. Motor is on the bench as of last nite but didnt have time to get at the broken bolt. This afternoon I'll tear into it farther. Pretty sure 3/8th bolts are in the future.
Looked at you tube for tapping aluminum, looks simple enough.
 

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I have a similar setup... Wondering if i am next

700 wildcat motor with 2000 ZR700 mounts, PSI pipes. I haven't snapped any mounts yet but i hear that the Rear Mag one is the issue. I also noticed that even with factory mounts all 4 corners don't want to sit level without a little shimming. I attach all 4 mounts to the engine first, than i drop that whole package in at once.

Maybe you need to install an additional torque brace on the front of the motor. Also the AC mounts are Cast aren't they.. Pretty flimsy.

Also I try and avoid Holeshotting mine all the time as i know what it can do to those mounts. But i am not super delicate with it either.
 

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Torque bumper has either .060 or .080 clearance, I have the factory service manual and adjusted it by that.
The center to center and offset was perfect. This engine use to have a B/M clutch kit on it that hit very hard off the line. Figured that is what was causing the broken aluminum mount. So I beefed it up to steel. Been great for years. I have a different clutch set up that isnt as hard on everything now.
But I've added about 20 horse's to the engine and better traction. Motor is on the bench as of last nite but didnt have time to get at the broken bolt. This afternoon I'll tear into it farther. Pretty sure 3/8th bolts are in the future.
Looked at you tube for tapping aluminum, looks simple enough.
I know you said it was by the manual but .060 is about 2x too much. My uncle has a sno pro with a 700 wildcat in it. Twin pipes 3* key and a clutch kit. It will stand on end when you pin it. Havent broken anything. Been running the setup for 5 plus years one of the rubber mounts is finally letting go now.
 

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Discussion Starter #8
Bolts came out with ease. It has two 1/4 inch spacers between it and the engine (factory installed) I'm not going to increase the size to 3/8ths, there just isnt enough material left around the bolt hole to do this. The problem was my fault, I didnt put lock washers on the bolts and they both came loose. One broke.i was sure I used lock tight but probably blue, which comes loose with moderate heat ( engine heat??) The threads in the engine are perfect, no damage. So today, new bolts with "shoulders" on them instead of completely threaded and lock washers and back in she goes. Should be running by 3 oclock today. I bought "Magic Tap" aluminum tapping fluid ($30 ouch) before I worked on it yesterday, oh well, I have in case I ever need to use it. 15 for the fluid and 15 to ship it. dam pricey.
 

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Magic tap is good stuff and it smells like big red.
Glad you found the issue. I still say tighten that torque bumper but tests just my opinion
 

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Discussion Starter #10
Had it running by 1:30 yesterday. Antifreeze all topped of and burped. Lock washers and blue loctite. These new bolt were 1/4 in longer and didnt bottom out, but it was very close to bottoming out.
I'll keep my eye on it from now on. Fairly easy to get at. Just reach down with a 1/2 inch wrench and check it when I put oil in the tank.
For once, everything went easier than expected.
I probably could have fixed it in the sled but, what the heck, it's fixed now and I'm confident it wont happen again.
I'll close the gap on the bumper stop to around .045 or so.
We put a few miles on her last nite. Everything seems kewl.
 
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