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just bought a 74 with a v8 conversion. nothing special, just a toy. but when driving it, anytime i get even close to being agressive, it feels like entire rear end of car is shifting to the right.

i know the rear end mount is bad, i can hear it. but had it on my lift and dont see anything else loose or bad.

Any recommendations or help would be greatly appreciated.

By the way, this is my seventh z car. but havent had one in over 20 years.

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1 hour ago, springtimemotors.jason@gmai said:

it feels like entire rear end of car is shifting to the right.

 

i know the rear end mount is bad, i can hear it. but had it on my lift and dont see anything else loose or bad.

 

 

What would you see?  There are eight bushings that could be deflecting/compressing, all rubber if they're original.  Two inner and two outer on each control arm.  People have found that the outer ones can completely disintegrate over time.  But you have to pry on them all to find out if they're worn.  

 

There are pictures around the internet of the back wheels of Z cars moving forward by quite a bit under the force of powerful engines.  The bushings are pretty thick and compress a lot.  If the rear is moving to the right it seems like the left wheel is moving farther forward than the right one, pointing inward and driving the rear to the right.

 

Just a guess.  The other possibility is that the front and rear aren't on the same lines, dog-tracking.  You can usually see that by eye, from the back.  If the rear end is already to the right it will try to drive past the front end under acceleration.

 

An alignment would tell you where you're starting from.  But the rubber bushings weren't designed for the power you're putting through them.  They're going to squish.  You just need to get them to squish evenly.  Seems like a good application for polyurethane bushings.

 

Just some thoughts.

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See picture. Red circles indicate components that could contribute to the problem you are experiencing.

 

Note that these cars are about 50 years old and we can expect that the suspension bushings, springs and shocks will need to be replaced.

  • Check that the mounting holes in the differential carrier bar (mustache bar) have not been hogged out.
  • Check the torque on all mounting bolts/nuts.

Suggest that you replace all of the old rubber bushings with polyurethane bushings on both the front and rear suspension.  Also, replace the rubber front differential mount with a solid mount. And no, the solid mount does not cause a lot of road noise. There are several options for a  solid front differential mount. Search Hybridz for details on the Ron Tyler mount and the the solid mount sold by Motorsports Auto (MSA).  The Ron Taylor mount is designed for racing and high horsepower applications.  The MSA mount is more suited for stock daily driver. I have used the the solid MSA mount on two SBC V8 240z projects (built 2001 and 2009) and have had no problems.

 

 

rear suspension.jpg

Edited by Miles
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