My 67 Coupe has all new suspension, CPP mini subframe with QA1 Coilovers and new rear leaf spring with new shocks. Also have subframe connectors. Under heavy acceleration, it seems like she is flexing and running a little sideways. Any thoughts on why this would be happening?
daddyohood
Funny feeling on hard acceleration
1 reading
Do you have limited slip? Are you running a separator plate behind your rear seat (sometimes referred to as a trunk firewall)? Those prevent a lot of body flex.
Torque boxes on both sides are also very important, if you've got an engine that makes a ton of torque, and work to prevent twist in an area where your chassis needs the most help.
Do you have an export brace and monte carlo bar?
Are the bushings on your springs and shackles in good shape, or rotty old 50+ year old rubber?
And lastly, what kind of engine and transmission are you running? Keep in mind, these cars were built originally to handle around 300-350 lb-ft of torque. The big-block cars got a little sketchy, even with the torque boxes and other minor tricks. If you have high numeric gears, and a mean engine making big torque, even the subframe connectors and improvements you've added may be hard pressed to prevent a bit of twist. They are floppy, compared to more modern cars with improved unibody construction.
Torque boxes on both sides are also very important, if you've got an engine that makes a ton of torque, and work to prevent twist in an area where your chassis needs the most help.
Do you have an export brace and monte carlo bar?
Are the bushings on your springs and shackles in good shape, or rotty old 50+ year old rubber?
And lastly, what kind of engine and transmission are you running? Keep in mind, these cars were built originally to handle around 300-350 lb-ft of torque. The big-block cars got a little sketchy, even with the torque boxes and other minor tricks. If you have high numeric gears, and a mean engine making big torque, even the subframe connectors and improvements you've added may be hard pressed to prevent a bit of twist. They are floppy, compared to more modern cars with improved unibody construction.
Check your U bolts are tight. You have to retorque them a few times when new in my experience
Same symptoms WOuld accelerate and it felt like the car had a sideways thrust to it that was not any sort of fishtailing or loss of traction
Same symptoms WOuld accelerate and it felt like the car had a sideways thrust to it that was not any sort of fishtailing or loss of traction
Potential issues include weak rear springs, extended shackles, loose u-bolts, leaf spring centerbolts too short, loose strut rods/bushings, wheel alignment, etc.
Does the CPP unit use the stock crossmember ?
Are you using the correct bolts for the engine crossmember . Regular bolts will not keep the frame rails from moving . The correct bolts have a conical shaft to lock the crossmember in place /
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also , there are crossmembers available that do a better job than the stock unit…….
Z
Are you using the correct bolts for the engine crossmember . Regular bolts will not keep the frame rails from moving . The correct bolts have a conical shaft to lock the crossmember in place /
also , there are crossmembers available that do a better job than the stock unit…….
Z
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