1450 Still Vibrates Like Crazy

[Don1450]

I Just got done with a major job on my 1450. I changed the ISO mounts, Changed over to a cast iron oil pan, did the welded cross bar mod to the cradle, and installed new flex couplers. Every bolt was replaced with Grade 8 and I used new washers, lock washers, and Loctite thread adhesive. I torqued the pan and cradle mounting bolts to 35 foot-pounds (tight). Tightened the ISO mounting bolts till 2-3 threads stuck out. These are the ones I used; got them at CCSpecialties.

ISO Mounts.jpg

While I was at it I changed the oil, sparkplug, checked the points, rebuilt the carb, spray lubed all of the linkages, and changed the differential oil and filter.

Started up like a dream! Roars at full open throttle and idles down to about 800 rpms without stalling.

But the vibration seems worse than before the changes. My mounts were nearly disintegrated and my cradle was sitting on the frame when I changed them out so it was pretty bad before. But now it seems worse. and there's one throttle position where I'm hitting a resonant frequency or something and at that point it feels like its going to shack itself apart.

What should I do?

[bocephus1991]

I don't know where cc specialist get their mounts, but if their not cub cadet they could be regular sway bar bushings like an auto parts store sells. They are more solid than the cub ones therefore don't absorb as much vibration. Have you tried rocking the engine to see if there's any movement? Other option is solid mounts, which is what I'm gonna do if I need to replace mine again.

[j4c11]

800rpm is very low for idle, it's supposed to be 1600 rpm (I think, check the manual for the exact number). Have you removed the governor arm and if so, did you follow the instructions in the manual for putting it back on?

Edit: it's supposed to be ~1200 not to exceed 1500. Something is off if your idle speed is 800, and it may be the cause of the vibration. My 1450 smooths out completely around 2600rpm. Check the manual for carburetor,governor and linkage adjustment procedures.

[Rescue11]

I used the same ones you did, had the same results even. Put your mower deck on it and run it for a month or so maybe even 2 and then see how you feel. Mine came out of it mostly, not smooth as a v-twin, but pretty decent overall. Did exactly what youDid

[johncub7172]

The old flex disc were perfectly fine, and broke in. The new discs you installed are still stiff as a board. Your hood hinge is most likely in need of a tighten. Tell us how bad that engine cradle was wallowed out. Mine were so bad I needed new ones. I had some good vibrations with those mounts. But I went and installed the factory mounts new from cub cadet. More than likely the carb settings could be off, and the points need attention.

[jaynjeep]

We went through this several years ago... The new MTD replacements are way too hard.. the tractor shook horribly.. I wound up going through an OLD IH dealer and he eventually found me 8 NOS IH bagged mounts.. the difference is amazing. Not sure what we will do after these mounts wear out! You would think someone would come out with an aftermarket mount that is more like the original IH ones.

[ol'George]

I have to agree with all of the above experiences.
When my $80.00 1650 came home from the auction, it was so smooth running
I thought it was a opposed twin.
Upon further inspection it had 1 loose bolt holding the pan to the iso rail.
The engine sat there merrily jumping around but transmitting no vibration to chassis.
It was like it was setting on a huge soft cushion.
Wished it was that smooth after I repaired everything.
Let the new mounts wear in and it will get better somewhat but it will never be like a twin of any kind.
And as others have said do take the hood hinge pin out and mash/squeeze the hinge to bring it back tight, point the pin and drive it back in/and install.
then tighten everything that rattles, one item at a time.
I was lucky inasmuch my iso's were original and good shape.
14-16 hp engines by nature being a big single, vibrate
Hell, when I was a young man, it cost $.25 to get a bed to vibrate like that in a motel room, and another $.25 to listen to a radio ( no TV then) Ha,LOL!

[olds45512]

Originally Posted by ol'George

Hell, when I was a young man, it cost $.25 to get a bed to vibrate like that in a motel room, and another $.25 to listen to a radio ( no TV then) Ha,LOL!

What kind of motel were you staying at? Did it have hourly rates?

[Yosemite Sam]

Originally Posted by ol'George

Hell, when I was a young man, it cost $.25 to get a bed to vibrate like that in a motel room, and another $.25 to listen to a radio ( no TV then) Ha,LOL!

Wow, you just don't see vibrating beds anymore, at least not in the motels we stay at... I do remember seeing them though.

It sounds like you did all of the repairs/upgrades right, did you check everything in the drive line?

You may want to try taking the drive shaft out and running the engine without it, if it doesn't stop shaking, that would at the very least eliminate that part of the machine from being suspect.

The guys may be right about adjusting the carburetor and setting the timing, either of those two things could make a world of difference.

Good luck.

[_DX3_]

The only throttle position any of my quiet lines felt "smooth" at was wide open throttle. Anything else always had a lot of vibrations and I always did the upgrades and mods to every QL I purchased. (the term smooth is open to interpretation.)

Did you check and replace the drive shaft bushings? If your ISO mounts were that bad, I would almost guarantee your bushings are shot because your drive line was way out of alignment.