NexTnmE

iTrader: (3)

This is my fist How-To so go easy on me. If anyone has tweaks please feel free to let me know.

I got the idea from another thread and finally took off the third (upper) trans mount and filled it solid. I followed the "How-to remove the fusebox" to get at the mount.

Since there is no polymount made for this third transmission mount you will have to fill it with something. A firm rubber caulking will do, I have been using an epoxy resin with activator that hardens fast, but still has some give to it.

Getting the mount out and back in is a pain in the @SS! Beware! So if you wanna try it, take a double shot of patience and start with this thread. Please follow the fist part of this thread. It is great!! https://www.cobaltss.net/forums/how-guide-43/how-fix-linkage-roll-pin-transmission-102830/

Once you get the fuse box out make sure you support the engine with a jack.

You can see three bolt heads that hold the mount to the transmission (on the right, near his finger in the last few photos). Sorry for stealing this photo, but this is where one is.





The rest of the mount is tucked inside the frame, and four bolts hold that in, going horizontally into the frame. Three you can easily get to, the fourth is almost underneath the portion that sticks out of the frame.

These pictures are of the mount removed.









Once you take the bolts out, you might want to lower the jack ease the removal. Just an inch or two.

This is my filled mount (view of the side thats in the frame). You can use a variety of materials to fill the mount. However, use something that will have just a little give. Also, clean and tape off one side so all your goo doesn't leak out onto the floor. Some electrical tape, or duct tape works well.







Make sure you remember what side is the top when re-installing. You can tell because the three bolt holes that go into the transmission are different heights. The far right bolt hole (1st number 3) is about a half inch taller on the top.





For re-installation, if you haven't already, you will need to lower the jack supporting the engine about and inch or two to get the transmission down far enough so you can put the mount back in easily. I finally got it in by putting the metal section down in first (section with three bolt holes) and then pushed the round part into the frame, seemed to work better and didn't hang up on the transmission.

Install the four horizontal bolts, then the three transmission bolts. No need to tighten like a guerrilla, everything could strip very easily.

So now I have all three transmission mounts filled. The shifting is even tighter and there is no wheel hop at all. When I had the two lower mounts, I got a slight "lobing" feeling, not hop, but almost. Now there is nothing!

Vibes are still noticeable, but at a different rpm range. Before, at idle the car would rattle. Now its more at like 1,000 - 1,100 rpms. I am happy with the mod and think it solves all my hop problems. Shifts like a champ too.

I can still feel a clunk when I'm doing spirited driving (shifting and letting off the clutch fast,, right when the clutch grabs it'll clunk). If you have the two mounts and the time to do this, I definitely would recommend this mod to complete the trifecta!

Thanks to N8s07SS and ralliartist for your write-ups and info!!

bridfi

are you sure the prothane insert wont fit it?

NexTnmE

iTrader: (3)

Probably not, but I'm not sure. The rubber on the stock mount is molded around the shaft that bolts to the transmission...I tried pulling it apart but had no luck. Also, it is slightly off center, and the poly mounts are right in the middle.

qwikredline

gee how is the vibration? changing ONLY the position at the rear, I rotated the engine; lifted the rear mount up with a spacer and dropped the front mount (lower) with relocated UHMW insert and power hop is gone. I tried both lower mounts changed to harder compound and the vibration was TERRIBLE! That convinced me to keep working. In all the Cobalt race cars in the GM build book the mid car passenger and driver mounts were left alone, but it is true these mounts are very flexible, the one you have changed is really soft, so stiffening it up would make a change for sure, but the vibration? Wow! when i did it too much I could feel the connecting rods going up and down lol! Why rotate the engine? THe power hop is mostly caused by misalignment of the axle shafts from trans shaft center line to suspension hub center line....

SprChrg4Life

iTrader: (1)

just a heads up to any1 interested in doing this mod (i feel it's important, hence the post of a near year old how-to!)

the 1/2" bolts that hold the fuse box in place are actually 13mm. 1/2" fits, but its extremely tight and hard to get the socket on the bolt if you already have it on the ratchet wrench.

another thing to mention: the 2 power wires on the fuse block secured by the 10mm nut/post are zip tied to the lower portion of the fuse block, so if the lower portion of the fuse block does not come out easily, cut the plastic clips that hold those 2 wires, as well as one clip for one of the wires that the fuse block gets secured into. 3 clips in total, as well as 2 star fasteners on 2 studs on the chassis.

one last thing... removing my 3rd tranny mount was difficult without lowering the engine down as low as possible but still supporting it with a jack. i took the 4x 13mm bolts, and the 3x 16mm bolts (or 17mm, can't remember) out for the 3rd mount and damn, i couldn't get that thing out for the life of me after turning it every which way... i did lower it down a bit too, but i still couldn't get it out. i took out the 2x 18mm bolts holding the front and rear tranny mounts to let the engine come down even more, and i rotated the 3rd mount 90 degrees (lifting the side closest to the front of the car upward). this revealed 3 bolts holding what appears to be an adapter between the tranny and this mount. rotating the 3rd mount allowed me access to the 3 bolts, removing this adapter-like bracket and allowing the 3rd mount to come out very easily.

just a heads up to any1 who's gonna do this mod, seeing as those are some of the things i experienced as i followed this how to. very nice write up, it gave me the confidence to do this!

oh and p.s.... you NEED to do this mod! wheel hop is completely erradicated, and i have all 3 other mounts (2x ttr poly trans bushings, solid upper). not to mention vibes are actually... less? couldn't be happier.

Chirpin them tires all day, not a single hop this needs to be done. a very fun project indeed

OBZ

subd

fmxr47

1/2" is 12.7 mm, so just use the 13 mm