Quote Originally Posted by FMS88 View Post
I had the same shudder issue after a long freeway drives. It hasn’t been a problem since I replaced the clutch while dealing with a seized pilot bearing. However (and to the forum at large), could the shudder be caused by flexing of the firewall?
It's possible, but that mostly happens if you have an uprated pressure plate on the clutch. I'd get someone to work the clutch while you watch the firewall around the adjuster. If it is moving/flexing it would be wise to reinforce the area before it cracks the sheet metal. I think the clutch friction disc/pressure plate is the culprit - could be a cheap clutch or contaminated etc as tortron has advised.