Hello. I own a 1999 Honda Civic Si with the original B16A2 and S4C gearbox. I've owned the car for 3 years and am the 2nd owner. It currently has 107k miles and ever since I bought it at 83k miles its had a problem with bucking with on/off throttle and clutch engagement/disengagement.

I have replaced both the halfshafts with DriveShaftShop axles. I replaced the torque mounts with HardRace ones. Transmission and Engine drivers side with Honda OE Mounts. The rear mount was replaced with Honda OE, and then Innovative 75A Polyurethane mount as of recently to see if it would help with the problem at all and still bucks. It does this moreso in lower gears and is less prevalent in higher gears. The only things I havent done are cracked open the gearbox or replaced the center shaft in the driveline. What could be my issue here? Differential? Transmission? Voodoo?

 

So the car is bucking or just the transmission? What clutch are you running?

 

The entire engine/drivetrain assembly. The clutch is a stock replacement at 90k miles along with the pressure plate and flywheel. It did the same both before and after the job.

 

Broken/worn spiders in the differential will cause excessive slack. So will a worn shaft the spiders ride on. They get burned up in a hurry with one tire fire burn outs.

 

So this could warrent the need of a new differential? I never pealed out in my car or had harsh takeoffs. Ive driven it hard before but I always let the rpm settle and I don't speed shift.

 

PO could have done plenty of burn outs.

 

Possibly. I never would have thought of it considering it was well kept and doesnt really have many issues besides this. I mean small stuff and the A/C but it just seemed old overall. Oh well. LSD time might be coming sooner than I thought if thats the case lol.