Help! My C4 is horrible over bumps
08-09-2010, 03:58 PM
#41
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I have some rear end questions and I don't know how, or if I can start a thread so I'll try posting here. I have a 114,000 mile 84 and when you are cruising and let off the gas, the rear will "drop" or move left, then when you accelerate it will get back up and over to the right like one or both of the rear wheels are "turning" in or out. I replaced the forward control arm bushings with poly ones an all 4 bars. I can't get any slop in the wheel bearings while on jackstands or any turn in from the tie rods either. I surely can't manually apply the force that the engine can but something is funky back there. I am new on the Corvette thing here so any advice will be greatly appreciated. Thanks in advance!!
08-09-2010, 04:13 PM
#42
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The '93 that I just bought a couple months ago rides like crap. I had new ball joints and control arm bushing installed. That settled it ever so slightly. I didn't have the $$$ for Bilsteins so I went with KYB's... I have to say I really like them! Maybe Bilsteins are better, but I'll never know as long as I have the car. It still swaps directions, lanes, etc when I hit a rough set of railroad tracks or off kilter bumps.
I'd be interested to hear more about what was mentioned above in terms of frame flex, and what can be done about it.
I'd be interested to hear more about what was mentioned above in terms of frame flex, and what can be done about it.
08-09-2010, 04:36 PM
#43
Team Owner
Pro Mechanic
08-09-2010, 04:49 PM
#44
Team Owner
Pro Mechanic
One of your rear tie rod ends is shot. Wheel is "steering" when on and off power.
08-09-2010, 04:50 PM
#45
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Pro Mechanic
08-09-2010, 05:12 PM
#46
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I hope that helps your tracking problem but it won't help the rear wheel hop at all. Neither will replacing run flats on the rear, it may help a little, but won't solve it. The rear end issue will take additional damping. You can get into trying to fix your ride for $1500 real fast if you are not careful.
08-09-2010, 05:35 PM
#47
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08-11-2010, 03:58 AM
#48
A long time ago there was an article in Corvette Fever about changing the alignment settings from the factory settings to get a more confident road feel. The c-4 vettes feel really "darty," for lack of a better word. It does not inspire confidence, and I don't like to drive my vette like you can in some Porsches. I hate when air gets under the front and it feels really light up over 100 mph. Scary. In other cars like the Supra TT, RX-7TT, 944T, c5 vettes, etc you can go way over 100 and feel like you are stuck to the road, but not in my 85 c4.
Last edited by black85; 08-11-2010 at 04:34 PM. Reason: to emphasize MY c4 for aboatguy
08-11-2010, 09:58 AM
#49
Race Director
A long time ago there was an article in Corvette Fever about changing the alignment settings from the factory settings to get a more confident road feel. The c-4 vettes feel really "darty," for lack of a better word. It does not inspire confidence, and I don't like to drive my vette like you can in some Porsches. I hate when air gets under the front and it feels really light up over 100 mph. Scary. In other cars like the Supra TT, RX-7TT, 944T, c5 vettes, etc you can go way over 100 and feel like you are stuck to the road, but not in the c4.
Here's a recent datalog 163 and ROCK SOLID so I suggest you change the end of your post tobut not in my C4 instead of tarring all C4s with your handling issues.........
Mike
Last edited by aboatguy; 08-11-2010 at 10:43 AM.
08-11-2010, 04:33 PM
#51
Well, mine may be different. It is an 85 w/ z51. It has decent Bilstein's all the way around. It is very stiff w/ 9.5" wheels and stiff spring rates. I think it also got a different ratio steering rack. It has always felt that way since I got it 9 or 10 years ago.
So other people don't get the feeling too much air is going under the front of the car at 125-130 mph? It lifts the front like a boat going over waves when you hit bumps or uneven pavement going that fast. In a good mk4 Supra, you can go way over 125 in corners on back roads and feel like you are going 55. The c4 is nothing like a newer sports car in that regard. You can hit a quarter and tell if it is heads or tails..... j/k
I'm not knocking the vette (I love my vette), but as the Corvette Fever article said (and I loosely paraphrase), if you don't think the stock c-4 feels nervous on the highway, you are in denial. I haven't read the magazine article in years, and they say the condition is easily solved by ditching the factory alignment specs. You just move a spacer in the front end somehow. Unfortunately, I think I may have just tossed 10+ years of Corvette Fever back issues when I moved, so I'm not going to have any luck finding the article. I will try though.
And, aboatguy, why are you showing me the datalog from your engine? Not quite sure what you are showing me here.... Are you suggesting my engine does not run well, and therefore my car does not handle well? I assure you that my car runs really well, and beats lots of cars at the drag strip. If you want, I'll post a datalog!
Dave
So other people don't get the feeling too much air is going under the front of the car at 125-130 mph? It lifts the front like a boat going over waves when you hit bumps or uneven pavement going that fast. In a good mk4 Supra, you can go way over 125 in corners on back roads and feel like you are going 55. The c4 is nothing like a newer sports car in that regard. You can hit a quarter and tell if it is heads or tails..... j/k
I'm not knocking the vette (I love my vette), but as the Corvette Fever article said (and I loosely paraphrase), if you don't think the stock c-4 feels nervous on the highway, you are in denial. I haven't read the magazine article in years, and they say the condition is easily solved by ditching the factory alignment specs. You just move a spacer in the front end somehow. Unfortunately, I think I may have just tossed 10+ years of Corvette Fever back issues when I moved, so I'm not going to have any luck finding the article. I will try though.
And, aboatguy, why are you showing me the datalog from your engine? Not quite sure what you are showing me here.... Are you suggesting my engine does not run well, and therefore my car does not handle well? I assure you that my car runs really well, and beats lots of cars at the drag strip. If you want, I'll post a datalog!
Dave
Last edited by black85; 08-11-2010 at 04:44 PM.
08-11-2010, 04:53 PM
#52
Race Director
Snap shot of a datalog showing my C4 going 163 MPH at 7:59am on 25 July 2010. Graph is the entire datalog...vertical black line is the point in time of the screenshot
IMO the Corvette Magazines are all advertisements... so I take them with a grain of salt. I know that lowering the car was a big point in getting rid of the 150-155 looseness
Mike
Well, mine may be different. It is an 85 w/ z51. It has decent Bilstein's all the way around. It is very stiff w/ 9.5" wheels and stiff spring rates. I think it also got a different ratio steering rack. It has always felt that way since I got it 9 or 10 years ago.
So other people don't get the feeling too much air is going under the front of the car at 125-130 mph? It lifts the front like a boat going over waves when you hit bumps or uneven pavement going that fast. In a good mk4 Supra, you can go way over 125 in corners on back roads and feel like you are going 55. The c4 is nothing like a newer sports car in that regard. You can hit a quarter and tell if it is heads or tails..... j/k
I'm not knocking the vette (I love my vette), but as the Corvette Fever article said (and I loosely paraphrase), if you don't think the stock c-4 feels nervous on the highway, you are in denial. I haven't read the magazine article in years, and they say the condition is easily solved by ditching the factory alignment specs. You just move a spacer in the front end somehow. Unfortunately, I think I may have just tossed 10+ years of Corvette Fever back issues when I moved, so I'm not going to have any luck finding the article. I will try though.
Dave
So other people don't get the feeling too much air is going under the front of the car at 125-130 mph? It lifts the front like a boat going over waves when you hit bumps or uneven pavement going that fast. In a good mk4 Supra, you can go way over 125 in corners on back roads and feel like you are going 55. The c4 is nothing like a newer sports car in that regard. You can hit a quarter and tell if it is heads or tails..... j/k
I'm not knocking the vette (I love my vette), but as the Corvette Fever article said (and I loosely paraphrase), if you don't think the stock c-4 feels nervous on the highway, you are in denial. I haven't read the magazine article in years, and they say the condition is easily solved by ditching the factory alignment specs. You just move a spacer in the front end somehow. Unfortunately, I think I may have just tossed 10+ years of Corvette Fever back issues when I moved, so I'm not going to have any luck finding the article. I will try though.
Dave
Mike
08-11-2010, 05:57 PM
#53
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To the OP... With 120,000 miles on it EVERYTHING in your suspension is worn out. I don't mean to the point of failure but to the point of sloppy and weak. Even if a visual inspection of everything 'looks good'. The durometer, integrity, and shape of the rubber in the bushings has changed. The springs have taken a set. And the shocks are definitely shot. (They were probably shot 80,000 miles ago!) You can't gauge the performance of a shock while it's on the vehicle unless it's really bad. You'd need to remove them and put them on a shock dyno to see how they've degraded.
You'd be well off to replace your shocks, even if it's not a set of Bilstiens, and find a set of Touring-type tires (Softer sidewall). Replacing all the sway bar mounts and end links with urethane will help make the car more stable, too, and it's much easier than replacing the major suspension bushings.
Rick - '92 LT1
You'd be well off to replace your shocks, even if it's not a set of Bilstiens, and find a set of Touring-type tires (Softer sidewall). Replacing all the sway bar mounts and end links with urethane will help make the car more stable, too, and it's much easier than replacing the major suspension bushings.
Rick - '92 LT1
08-11-2010, 06:36 PM
#54
When I changed all of my suspension bushings, shocks , tires, 4 wheel alignment. . . my car rides like a brand vette. It is stable at all speeds and while it still darts just a little on bumpy roads, the car instills confidence. Before all of that, the car used change lanes when it felt like it
BTW, I have a 1996, and I used the softer KYB shocks. I drive this vette in the bumpy city of New York ocassionally. Try driving on the BQE someday! That is a true test of any suspension.
BTW, I have a 1996, and I used the softer KYB shocks. I drive this vette in the bumpy city of New York ocassionally. Try driving on the BQE someday! That is a true test of any suspension.
To the OP... With 120,000 miles on it EVERYTHING in your suspension is worn out. I don't mean to the point of failure but to the point of sloppy and weak. Even if a visual inspection of everything 'looks good'. The durometer, integrity, and shape of the rubber in the bushings has changed. The springs have taken a set. And the shocks are definitely shot. (They were probably shot 80,000 miles ago!) You can't gauge the performance of a shock while it's on the vehicle unless it's really bad. You'd need to remove them and put them on a shock dyno to see how they've degraded.
You'd be well off to replace your shocks, even if it's not a set of Bilstiens, and find a set of Touring-type tires (Softer sidewall). Replacing all the sway bar mounts and end links with urethane will help make the car more stable, too, and it's much easier than replacing the major suspension bushings.
Rick - '92 LT1
You'd be well off to replace your shocks, even if it's not a set of Bilstiens, and find a set of Touring-type tires (Softer sidewall). Replacing all the sway bar mounts and end links with urethane will help make the car more stable, too, and it's much easier than replacing the major suspension bushings.
Rick - '92 LT1
08-11-2010, 08:39 PM
#55
Race Director
Well, mine may be different. It is an 85 w/ z51. It has decent Bilstein's all the way around. It is very stiff w/ 9.5" wheels and stiff spring rates. I think it also got a different ratio steering rack. It has always felt that way since I got it 9 or 10 years ago.
So other people don't get the feeling too much air is going under the front of the car at 125-130 mph? It lifts the front like a boat going over waves when you hit bumps or uneven pavement going that fast. In a good mk4 Supra, you can go way over 125 in corners on back roads and feel like you are going 55. The c4 is nothing like a newer sports car in that regard. You can hit a quarter and tell if it is heads or tails..... j/k
I'm not knocking the vette (I love my vette), but as the Corvette Fever article said (and I loosely paraphrase), if you don't think the stock c-4 feels nervous on the highway, you are in denial. I haven't read the magazine article in years, and they say the condition is easily solved by ditching the factory alignment specs. You just move a spacer in the front end somehow. Unfortunately, I think I may have just tossed 10+ years of Corvette Fever back issues when I moved, so I'm not going to have any luck finding the article. I will try though.
And, aboatguy, why are you showing me the datalog from your engine? Not quite sure what you are showing me here.... Are you suggesting my engine does not run well, and therefore my car does not handle well? I assure you that my car runs really well, and beats lots of cars at the drag strip. If you want, I'll post a datalog!
Dave
So other people don't get the feeling too much air is going under the front of the car at 125-130 mph? It lifts the front like a boat going over waves when you hit bumps or uneven pavement going that fast. In a good mk4 Supra, you can go way over 125 in corners on back roads and feel like you are going 55. The c4 is nothing like a newer sports car in that regard. You can hit a quarter and tell if it is heads or tails..... j/k
I'm not knocking the vette (I love my vette), but as the Corvette Fever article said (and I loosely paraphrase), if you don't think the stock c-4 feels nervous on the highway, you are in denial. I haven't read the magazine article in years, and they say the condition is easily solved by ditching the factory alignment specs. You just move a spacer in the front end somehow. Unfortunately, I think I may have just tossed 10+ years of Corvette Fever back issues when I moved, so I'm not going to have any luck finding the article. I will try though.
And, aboatguy, why are you showing me the datalog from your engine? Not quite sure what you are showing me here.... Are you suggesting my engine does not run well, and therefore my car does not handle well? I assure you that my car runs really well, and beats lots of cars at the drag strip. If you want, I'll post a datalog!
Dave
Mike
08-11-2010, 10:33 PM
#56
I agree completely with this, and think it will continue to be a part of your problem as long as you keep them on your car. You lose a noticable amount of cushioning with those lower profile tires.
08-11-2010, 10:37 PM
#57
aboatguy--
You are so right about Corvette mags being one big ad. That is one reason I no longer subscribe to any or felt I should keep any back issues. In this instance though, there was no sell. It was just an alignment article. Usually though, it is biased.
BTW, 163 mph? Didn't notice that at first glance. NICE!!!!
Dave
You are so right about Corvette mags being one big ad. That is one reason I no longer subscribe to any or felt I should keep any back issues. In this instance though, there was no sell. It was just an alignment article. Usually though, it is biased.
BTW, 163 mph? Didn't notice that at first glance. NICE!!!!
Dave
08-12-2010, 01:39 AM
#58
Burning Brakes
To the OP... With 120,000 miles on it EVERYTHING in your suspension is worn out. I don't mean to the point of failure but to the point of sloppy and weak. Even if a visual inspection of everything 'looks good'. The durometer, integrity, and shape of the rubber in the bushings has changed. The springs have taken a set. And the shocks are definitely shot. (They were probably shot 80,000 miles ago!) You can't gauge the performance of a shock while it's on the vehicle unless it's really bad. You'd need to remove them and put them on a shock dyno to see how they've degraded.
You'd be well off to replace your shocks, even if it's not a set of Bilstiens, and find a set of Touring-type tires (Softer sidewall). Replacing all the sway bar mounts and end links with urethane will help make the car more stable, too, and it's much easier than replacing the major suspension bushings.
Rick - '92 LT1
You'd be well off to replace your shocks, even if it's not a set of Bilstiens, and find a set of Touring-type tires (Softer sidewall). Replacing all the sway bar mounts and end links with urethane will help make the car more stable, too, and it's much easier than replacing the major suspension bushings.
Rick - '92 LT1
This guy has it correct U joints and wheel bearings too . Just went through it myself ,
08-12-2010, 09:05 AM
#59
Race Director
I've found the sway bars can make the car much more harsh. Replace the bushings with poly, put a washer between the mount halves, add zerks and lube them. With the end links disconnected the bars should move freely. If they do not they are acting as shocks.
08-12-2010, 09:34 AM
#60
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It can ... but, it sounds like he needs some suspension CONTROL. Without control the suspension will be all over the place, perhaps causing the darting, bump steering, and lane changes. Sway bars and shocks can go a long way to dampen those unwanted movements. And it doesn't seem like he'll want to tackle changing all his bushings. Rick - '92 LT1