Rear end drop

I was out cruising today and spotted a 77 that looked pretty good at a car dealer. I had to stop and look at it just to find the price. Well anyway I looked it over and it was in decent shape and ran pretty good for 167,000 miles. I did notice that when you put it in gear (auto trans) the rear end dropped about 2" . By this I mean the body height dropped 2". I thought this was odd and quite excessive. Maybe its the rear spring that has lost it's guts, but It could be something else. Anyone have this happen to them ?

[78SilvAnniv]

When the engine is idleing fast and I put my 78 automatic in gear, the transfer of the engine's power through the transmission and to the rear end is what makes the vette 'squat' when the two axles take the power load.

Think of it as a feline predator getting ready to pounce! (thankfully it doesn't do that little 'wiggle-butt' motion before it takes off! That'd be a clue for serious problems!)

The vette will also do this at a low/normal idle, just not as pronounced as when the idle is high.
Silver

[c4ever]

Silver,

I like the way you put that. It's true resto. Not at all like the C4.
That's why it's called a SHARK. Ready to pounce

Silver,
That may be the problem but I thought it was just too much drop. I had a 69 with an auto trans and I don't remember it squatting that much, but I know exactly what you are referring too.

Roy

Do you mean that clams don't pounce ???? ( no offense to the c4 owners)
Roy

[c4ever]

Quote"Do you mean that clams don't pounce ???? "

The word is "Predator"

We don't pounce we anihilate

[78SilvAnniv]

I notice that when the idle is high, 78 will squat a GOOD 2-3 inches. I even notice the nose come up a bit when it squats. That indicates to me, that the rear must be lowering quite a bit for me to notice the nose coming up that significantly.

Now, when the idle is not high, the squat is not as deep, because there is less power at the lower rpm's to transfer to the rear end and half-shafts. I still notice it 'set down' a bit, but not like when it is cold out and the engine hasn't warmed up completely.

If your previous vette was a warm-weather vette, and well maintained (with little to no high idle conditions) you may not have experienced the deep lowering of the rear end. Plus, you say it's been a while since you've driven a shark.

Usually, stories grow with the telling, but sometimes they also diminish in our memories and the truth becomes forgotten. I am in no way a mechanic, but in logically thinking of how the rear is put together, I don't feel the leaf springs or shocks would have anything to do with how the vette handles taking the power load from the engine to the rear wheels. That is strictly a drive train funtion. I think it is the movement of the half shafts between the rear end and the wheels that cause the vette to lower like that.

Maybe the trailing arm bushings being missing would cause the vehicle to lower even more? I don't know. Take it for another drive, just for fun!

btw, a clam will take anything you throw at it and give you back a pearl. Sort of like an 'awful' twisty road being thrown at the vette and being given a great drive!
Silver

[Hib Halverson]

Originally posted by resto75
I was out cruising today and spotted a 77 that looked pretty good at a car dealer. I had to stop and look at it just to find the price. Well anyway I looked it over and it was in decent shape and ran pretty good for 167,000 miles. I did notice that when you put it in gear (auto trans) the rear end dropped about 2" . By this I mean the body height dropped 2". I thought this was odd and quite excessive. Maybe its the rear spring that has lost it's guts, but It could be something else. Anyone have this happen to them ?

Base suspension with tired shocks---I can see how you'd get that much squat when you pull it into gear.