MKII Vibration blues

[vwnut84]

Okay, so I have recently swapped in an AAZ into my '91 Jetta Coupe.  My issue is in first and second gear when really getting on it, I am getting what feels like a vibration due to a bad motor mount.  The vibration seems to resonate through the cabin, and is coming from the subframe area (lower firewall/floor).  It's really starting to get on my nerves.  I have just installed all new mounts (front hydro, rear hydro, and new stock trans mount) and the issue still persists.  This was never an issue with my N/A thanks to the lack of power haha.  Front engine subframe bushings are also new.  Control arm bushings are new, and the subframe bolts are all tight, and when the control arm bushings were replaced, the TTY bolts were replcaed as well.  So I am wondering if anyone else has had this issue?  Or is this almost a normal condition?  I'm almost at the point of replcaing the subframe with a MKIII one so I can use the newest/best designed mounts I can.  The thought also crossed my mind that this is a normal condition, but that seems unlikely.  I can't see this being an acceptable condition in a new car of ten years ago, and the structure of the MKII as we all know is damn near identical to the MKIII the engine originated in.  Any input would be great, Thanks guys!!!  Hopefully this is something stupid I am overlooking.

[CRSMP5]

what downpipe did you use? is it hitting anything?? aaz = taller and well id expect it to rub on something..

[rodpaslow]

I must stress, you cannot use a MK3 subframe in a MK2 car because the MK3 has a wider track than the MK2.  It sound to me like you may have used the CV shafts from the MK3 as they are longer and will rub against the transmission flanges and produce what you are describing.  The MK3 subframes are also taller than the MK2 which would cause serious problems.

I don`t know who told you, but the subframes are not damn near identical.  There is just enough differences that you cannot interchange them.  I found out the hard way destroying a couple CV shafts with the vibration you describe!

[vwnut84]

CRSMP5:  I made my own downpipe from the top half of the MKIII, and then made the rest.  There is about 3/4" of clearance over the steering rack, and I made a note today to take a look at it and see if it was hitting and I did not see any indication of rubbing, but now that you mention it, maybe it's only hitting just enough to make contact, and not really make any marks.  I'm going to take a better look at that tomorrow though because that would clearly make the problem I'm encountering.   

rodpaslow:  After more thought on it, I dismissed the idea of the MKIII subframe because at this point I really don't think it is a mount issue anymore (and at idle it's actually nice and smooth now).  I had thought that the subframes from the MKIII and MKII were a fit, and that the control arms/tie rods were the actual pieces that were longer to make the wider track.  You learn something new all the time!  Also, I am using the same axles as before, that have been in the car from day one, as well as the transmission.  I had thought about a bad/binding axle, but usually I've had axles fail the other way around (when accelerating on the highway in fifth, but not only in first and second gears)

Thanks for the input guys!!!  I'm really leaning towards the downpipe now, and I'm going to look further into it tomorrow, or at least put some grease pen marks on it and see if they get marked up. 

[wdkingery]

I thought I sold my drop springs to a guy who had a vr6 with a mk3 subframe in an 87 jetta..? So he said..

[vwnut84]

Well I figured it out.  Over the weekend a friend of mine had given me the "new" hydro rear mount, which turned out to be not so new.  I put my old solid mount back in this morning, and the vibration went away.  The actual cause of it was the rear trans mount (when I took it out and turned it upsode down liquid came out), but I was thrown off by the bad rear mount I installed.  I am thrilled to death now.  I knew it had to be something dumb.

Thanks for all of the help guys!!!

Moral of the story, a part is never "new" unless you're taking it out of the package.