Harsh Vibration

[Oldmacdonald]

Hi All, I have been a member here since being press ganged by Rob into joining at last years Classic Motor show. Still Looking for a perfect (for Me) C3.
I've had a look at a couple, but found them both feeling what I can only describe as harsh vibrating when test driving, not particularly noisy, just sort of rough, as if there was no rubber in the engine mountings, and you got it all in the drivers seat.
Now is this normal, and I am just used to being cosseted in a modern car, and therefore it is part of the experience, or do I need to look further?
I really like the C3 shape as to me it really is the Classic, but after trying a C5 I am seriously considering a change of allegiance.

Your thoughts would be appreciated

Thanks

 

[antijam]

Certain car design is pretty timeless, the Jaguar E type, the Ferrari Dino and dare I say it - the C3 'Vette as examples. Their looks stand the test of time, their mechanics don't. Automotive engineering has come a long way in 50 years. Underneath the C3 was still a C2 and those are nearly 60 years old now. I love my '71 but I'm not blind to the fact that in terms of comfort the driving experience is a very long way behind my 2016 Mustang. Your perfect C3 is out there if you take it for what it is - and what it isn't is a modern car.

 

[Roscobbc]

Engine design has also come a long, long way in the last 60 years.......its perhaps interesting to compare two similar capacity V8 engined cars from the same period and how they achieve (or not) a level of smoothness and lack of vibration. A Rolls Royce for example gets its engine smoothness (as many earlier Cadillacs and Lincons did) by using lower compression ratios and incredibly 'soft' valve timing that perhaps reduced potential power output by 50% or more. A C3 Corvette still had relatively conservative cam timings even on some of the higher output variants (L88 excepted although this was never a 'street' engine) mainly to avoid warranty claims. Rolls Royce ride comfort of the same period was obviously achieved by very soft spring rates and dampers with special 'soft squidgy' tyres from Avon. A C3 in contrast would come with springs and dampers that were still considered soft by Europeans with even the optional Slalom suspension that Americans though far too hard (but considered too soft on our side of the Atlantic). When I sit in stationary traffic in my Vette and watch the body lightly rock in unison with the 'lopey' idle from high compression and a hot cam gives I'm also concious of the various other things in the car that rattle and buzz, also in unison with that performance.......much the same when driving......with modern 'fat' radial tyres (and not the useless bias belted rubber of the day) I am acutely aware noise of running over every single irregularity and pothole on the road surface. I'm sure fellow drivers in MGB's and TR4's will be saying much the same thing.......yes a C5 or C6 will give a more comfortable and peaceful ride (as you would expect). What I like about a C3 is that the chassis tells your 'ass' exactly what is going on underneath......even if you ignore the warning signs and react too late to correct things............

 

[Oneball]

I think you should try another one. You are less isolated from the road in an older car but usually the suspension is softer than a modern car so it rides better over bumps. Engine may be less sound insulated than a modern car but a vibration you can feel from it isn’t something I’d describe as right. Maybe find a member here that can take you for a ride.

 

[johng]

I'd say you are being spoilt by modern car design. If you look at say a Focus suspension, there is probably 10 times the rubber volume in the suspension bushes than a C3 and while it is designed to be stiff laterally it is soft longitudinally to avoid impact harshness. There are voids and even chambers containing fluid to provide damping in the bushes. The same goes for engine mounts, most modern designs are set up to have the main support on the torque roll axis (which can again be relatively soft with damping chambers built in) with a separate stiff roll restraint to react engine torque. The C3 has 3 hard blocks of rubber underneath it. Also car companies now have hundreds of engineers whose sole job is to eliminate squeaks & rattles both at the design stage and at the production plants. There are things you can do to cut down on the squeaks and rattles, but not really anything to change the fundamental design. Personally I find it all part of the experience

 

[Chuffer]

As the other guys have said , a C3 is classic car with with all the faults and foibles of a car that is at least 41 years old and bares no comparision with a modern car . But like Oneball said , harsh vibration suggests something amiss . Rattles and squeaks are part of the deal with classic cars , especially T Tops but I have done hundreds of fund raising `Dream Rides` for childrens charities in my 1980 C3 and the most common comment from passengers after being wowed by the looks and the sound was that they were surprised how comfortable it is . And thats running on KYB gas shox and poly bushes . Keep looking and stick to your quest for a C3 as it`s your `first love` . Buy anything else and you may never be happy with your choice . Good luck.

 

[Roscobbc]

Sometimes an aftermarket exhaust system can 'rest' against a body or chassis component creating vibration that may only be felt at certain rpm.

 

[Chuffer]

I dare say that warn and perished body mount bushes would contribute to vibration in the cabin too .

 

[CaptainK]

I must confess I was surprised when I got my 1968 C3. Before I started looking at them I was very much in the mindset of "old car won't be as smooth and comfortable as new car". But actually, I find my C3 very comfortable and rides very smoothly. I was quite impressed. No engine vibrations I can feel, and bumps are dealt with smoothly. The only minor issues I have are the standard issue minor squeaks and rattles. I've cured a few, but there are still more. But its all part of the old car experience. It helps that I have sidepipes, as that "cures" quite a lot of rattles

 

[James Vette]

Yes the C3 is a somewhat rough ride because it was designed with flat american roads in mind instead of our nasty UK roads. In my opinion the car handles amazing but makes nasty sounds and shakes. Now that might be because it's 50+ years old or because of what I said before. Nothing is perfect in life and you have to accept that. You can always sell it if you don't like it and it won't lose any value being a classic. Goodluck.

 

[Mad4slalom]

Yes the C3 is a somewhat rough ride because it was designed with flat american roads in mind instead of our nasty UK roads. In my opinion the car handles amazing but makes nasty sounds and shakes. Now that might be because it's 50+ years old or because of what I said before. Nothing is perfect in life and you have to accept that. You can always sell it if you don't like it and it won't lose any value being a classic. Goodluck.

does it still have the steel rear leaf spring.? The po of my 72 changed it out for a composite mono leaf and said the difference was dramatic. He had previously changed or renewed all other drivetrain bushes and rubbers and it was still a big improvement. I have always thought how well she absorbs bumps, not crashy like my z4 m coupe at all,(and that was over thirty years newer)
And corners really flat with no roll.

 

[Roscobbc]

Seemingly simple changes can make dramatic differences.......the stock GM Vette front engine mounts are effectively of a three piece 'captive' design.......so two metal pieces with a bonded rubber pad to absorb some engine vibration.......designed not be too rigid or too 'soft' allowing the engine to 'flop' around. The clever part of the design is the two metal halves of the mount interlock.....if the bonded rubber centre part gives way..........and with higher power engines the bonding does fail......frequently. The interlock design stops the engine riding up and hitting the underside of the hood or the viscous fan 'eating' the fan shround.All that happened to my engine combo.........when I installed the new engine WITH a pair of front engine mounts on its first drive one mount lasted about two hundred yards before 'separating'.
The point I wanted to get to was that the addition of poly engine mounts 'firmed-up' the engine in the frame......surprisingly improved gear shift quality yet didn't seem to detrimentally effect any transferred engine vibration in to the body and frame.

 

[Chuffer]

Totally agree with you Mad4 . The C3 is not a rough ride at all for a design that`s so long in the tooth .Unless it`s a nackered one ! Yes, our roads are crap and will only get worse the way I see the future of this country but when you but factor in firm suspension , the fad for low profile tyres on just about everything , plus the dreaded run flats and most modern cars crash about . My mates Lexus Hybrid nearly shakes my fillings out every time he hits a bump in the road . Give me my Grand Cherokee on high profile `Town & Country ` tyres anyday . The C3 runs on 255 / 60 front and 295 / 50 profile rubber that absorbs a lot more impact than modern cars and as you say , and it corners as flat you like .

 

[Mad4slalom]

Totally agree with you Mad4 . The C3 is not a rough ride at all for a design that`s so long in the tooth .Unless it`s a nackered one ! Yes, our roads are crap and will only get worse the way I see the future of this country but when you but factor in firm suspension , the fad for low profile tyres on just about everything , plus the dreaded run flats and most modern cars crash about . My mates Lexus Hybrid nearly shakes my fillings out every time he hits a bump in the road . Give me my Grand Cherokee on high profile `Town & Country ` tyres anyday . The C3 runs on 255 / 60 front and 295 / 50 profile rubber that absorbs a lot more impact than modern cars and as you say , and it corners as flat you like .

I have always said chuffs, that cambelts are for turning camshafts , Not for stretching over wheels. I like a bit of sidewall I guess its an age thing

 

[Chuffer]

I have always said chuffs, that cambelts are for turning camshafts , Not for stretching over wheels. I like a bit of sidewall I guess its an age thing

Gives a whole new meaning to `Rubber Fetish`

 

[curious bystander]

Could the vibration that "oldmacdonald" talks of just be old hard and maybe flatted tyres?

 

[Vetman]

My 75 C3 has good suspension with regular springs and dampers but uprated roll bars. Some road surfaces or expansion joints are painful, as are drain covers in the inside lane. My exhaust is quite low so speed bumps are another problem at certain speeds.

I avoid what can be avoided and clench my buttocks for the rest.

 

[Chuffer]

Could the vibration that "oldmacdonald" talks of just be old hard and maybe flatted tyres?

A good point Bill , and not too much of a streatch of the imagination that both cars he drove displayed the same symptoms . If they were little used like most classics then `flat spotting ` may well occur if the cars are not stored properly and the tyres could be very old too and as hard as a drum even if they have good tread depth .

 

[Mad4slalom]

Could the vibration that "oldmacdonald" talks of just be old hard and maybe flatted tyres?

possibly I wound mine over today and did what chuffer said and rolled it forward half a wheel

 

[teamzr1]

Talk about harsh ride,
Look at the attached GM spec PDF of a 1913 Chevy Baby Grand model, cost $750 new

Imagine almost no paved roads what the ride quality, was not