ISO mount replacement

lowlyfzlucky · #1 07-23-2010, 02:50 PM

This seems like a pretty straight forward job, but anyone got any tips or areas to look out for? Anything to worry about disconnecting the shaft?

_DX3_ · #2 07-23-2010, 03:28 PM

If your going to be in that far, and the engine will be out, check both ends of the drive shaft for wear, where they ride in the shaft bushings. My 1250 shaft was very well worn, so I am going to pick up a piece of 5/8 round stock and make a new shaft. Also is a good time to replace the rubber flex couplings. Again mine were well worn, and the coupling at the rear was really stretched forwards, so I ordered three couplings and will put two on the rear and one new one on the front. Great time to replace roll pins too. Both of the shaft bushings on mine had fallen apart, and I did not realize how they were supposed to be seated until Matt gave me some pointers. So I will be ordering those items here in the near future. Yours may end up being just fine, but just thought I would pass along some issues I found with mine and had no idea they were bad. Thank goodness for this forum and the guys here with great knowledge.

TEET · #3 07-23-2010, 04:34 PM

I've replaced mine without removing the engine...its a tight squeeze, but can be done. Just need to jack up the engine a tiny bit after the iso mounts are loosened up, and support the cradle with something, like a wedge....I think I used a pry bar resting between the frame and cradle to give me some room.

If you do feel the need to remove the engine, just double and triple check that everything is disconnected, check the drive shaft bushing, and bottom of the oil pan for damage...when the iso mounts go it tends to rub against the front axle bolt, or center frame rail.

Jeff (teet)

nix1650 · #4 07-23-2010, 11:16 PM

since the engine is out you should also pull the front crossmember together where the front axle goes. It takes care of a lot of steering slop.

lowlyfzlucky · #5 07-23-2010, 11:37 PM

Thanks for all the help guys. I did close up the C channel while I had the motor out and the axle is a much better fit now. I have it all back together, but have one question: How tight should the bolts be torqued that hold the drive shaft on? What should the flex look like when properly installed?

Matt G. · #6 07-23-2010, 11:45 PM

You can't really torque the bolts that hold the rag joints and driveshaft together because of the locknuts. Just tighten them until the disc starts to deform slightly. Don't overdo it, or the rubber discs will have a very short life.

lowlyfzlucky · #7 07-24-2010, 12:03 AM

Quote:

Originally Posted by Matt G.

You can't really torque the bolts that hold the rag joints and driveshaft together because of the locknuts. Just tighten them until the disc starts to deform slightly. Don't overdo it, or the rubber discs will have a very short life.

The disc seemed to be pretty deformed before I took it apart, so I'm wondering if it should really have that much flex in it. Right now, it's about 3/4" from being flat. This sound right?

_DX3_ · #8 07-24-2010, 12:10 AM

My rear disk was about the same. That is why I decided to put on new disks and doubled up the rear to take up the amount of deforming from the single disk. Wish I had gotten a picture of it before I took it off.

lowlyfzlucky · #9 07-25-2010, 12:36 AM

Does anyone have pic of one that's properly installed?

Matt G. · #10 07-25-2010, 10:05 AM

Here's a factory one that's never been touched. Tighten them so it looks like this, or maybe even a bit less. Just enough to deform the rubber slightly. If you are re-using the original bolts, use new nylock nuts, as the original locknuts rarely hold when re-used in my experience.