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TR4/4A TR4A IRS Rear Suspension Knock

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KVH

KVH

Obi Wan
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On my IRS, which has a lightened flywheel and a LSD Nissan differential, I'm experiencing some great handling and driving, but I'm also feeling what seems to be a slight knock (like a little kick in the tail) when I shift into second or third at hight RPMs.

Am I hearing a U-Joint issue? I guess there are six to worry about (2 at the driveshaft and 2 at each axle shaft) Something else?
 
Hopefully just u-joints. The IRS has the same differential mounts as the TR6, and the pins and mounts should be checked. Have you check those yet?
 
When you are torquing good, say in 2nd or 3rd around 3300 and let off the gas suddenly, do you hear it ?
 
Ah, there's a lot going on back there so potential for one of several issues. It would be good to hear more detail on the noise and exactly under what conditions you hear it. Possibilities include:

1) differential mount pins (usually heard pulling away in 1st gear)
2) u-joints as suspected (usually heard puling away in 1st gear)
3) sticking splines in the axle shaft slip joints (this occurs when letting off the power during a long sweeping turn. The torque tends to keep unlubricated slip joints stuck until the foot is raised off the gas and "jink" they slide just that little bit with a very odd sensation in the rear end).
4) trailing arm bushings

1) and 2) usually result in a knock or cluck. 3) and 4) actually can give a twitch in the handling.

Bob
 
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