Why different characteristics under acceleration '65 vs '80?
Thread Starter
Race Director
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Why different characteristics under acceleration '65 vs '80?
My Dad had a '65 327/350 4spd which I recall being really quick. Suspension was stock.
Recently I got an '80 with a ZZ4 350 with a small Weiand 142 blower, 700R4 auto trans. Some mild suspension upgrades, nothing radical - VBP composite 330 rear monospring, VBP adjustable struts with poly bushings, I think the swaybars may have been upgraded, Bilstein shocks. Stock front springs and hardware.
My recollection is that Dad's '65 stayed basically flat under hard acceleration - the nose may have come up some but not like this '80. With my '80 the nose really comes up, even if I'm at 60 when I punch it. Is this explained completely by whatever extra hp the blower is generating or are there other factors?
Recently I got an '80 with a ZZ4 350 with a small Weiand 142 blower, 700R4 auto trans. Some mild suspension upgrades, nothing radical - VBP composite 330 rear monospring, VBP adjustable struts with poly bushings, I think the swaybars may have been upgraded, Bilstein shocks. Stock front springs and hardware.
My recollection is that Dad's '65 stayed basically flat under hard acceleration - the nose may have come up some but not like this '80. With my '80 the nose really comes up, even if I'm at 60 when I punch it. Is this explained completely by whatever extra hp the blower is generating or are there other factors?
Last edited by brassplyer; Jan 8, 2020 at 02:34 AM.
Safety Car
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From: Seattle Washington
Keep in mind that basically they have the same frame and with the same components they should do the same thing. And that way You remember when You were young was always better than what reality is today. The 330 Lb Spring might be a bit soft for that kind of power and its not so much the front is coming up as the rear is squatting down.
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could be the shocks, the gear ratios of the transmission, the rear end rearing that could affect the difference you feel. Generally it s the torque that gets the front end to rise and the resistance of the shocks that resist it. When your rolling up to a stop and you slam on the brakes at 5 to 10 mph does the nose dive abruptly? That would indicate softer shocks. you can also stand next to the car and pump the front end with you hand and how quickly it stops when you stop is how the shocks are functioning. You could just so much more power than your Dads 65 that you are experiencing some exceptional torque
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The spring rate of the rear spring makes a huge difference. The '65 had a big-*** multi-leaf steel spring that was about as harsh as the suspension on a tractor. The '80 uses a nice, soft composite spring so they could sell a nice-riding car to secretaries. That "secretary suspension" will make the '80 "squat" like a 300ZX under any acceleration. I just recently changed out the multi-leaf steel rear spring on my '64 with a "modern" composite spring. Now my '64 rides much nicer, and it "squats" on acceleration.
Lars
Lars
Last edited by lars; Jan 8, 2020 at 03:28 PM.
Melting Slicks
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From: Dunedin NZ.
You don't say what model Bilstein shocks are fitted, if you have HD's in back I would suggest changing them to Sport version to better match that spring. I have tried both with that spring and the Sports were much better matched JMPO
Thread Starter
Race Director
Joined: Nov 2018
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The spring rate of the rear spring makes a huge difference. The '65 had a big-*** multi-leaf steel spring that was about as harsh as the suspension on a tractor. The '80 uses a nice, soft composite spring so they could sell a nice-riding car to secretaries. That "secretary suspension" will make the '80 "squat" like a 300ZX under any acceleration. I just recently changed out the multi-leaf steel rear spring on my '64 with a "modern" composite spring. Now my '64 rides much nicer, and it "squats" on acceleration.
Lars
Lars
Do steel vs composite springs of the same rating behave differently? I weigh well north of 250 lbs and when I push down on the fender it barely budges.
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A ZZ4 with blower is going to have significant Gross HP over the 355 Gross HP with a ZZ4. I can tell you that a 330 composite spring with high hp is going to be way too soft to prevent squatting, X2 if the Bilstein is a heavy duty Bilstein. The Bilstein Sports are 30% stiffer than the HD's. At the very least, that car would need a 360 spring and most likely a 420 composite. A 420 composite with Bilstein Sports will be much more level on acceleration......
Last edited by jb78L-82; Jan 8, 2020 at 06:47 PM.