Corvair DiagramCorvair Photo
Corvair Center
home forum corvairs calendar links Corvair Podcast
California Corvairs
Clarks Corvair
Clarks Corvair
“CORSA"



Chevy Corvair License Plate
Chevy Corvair Chrome Wheel
Corvair Center Forum :  Corvair Center Phorum The fastest message board... ever.
Corvair Center 
Cowl Shake Finally (and unexpectedly) Resolved!
Posted by: gbirk1 ()
Date: November 05, 2017 03:49PM

I bought my 67 Monza vert in 2010 out of Florida. Since I was not able to view the car in person, I paid (what I thought was) some pretty good dollars to have someone inspect the car for me prior to purchase. Alas, the person was not a Corvair expert, and he missed a bunch of stuff (wish I had know about this forum at that time).

When the car was delivered, my family and I put the top down, hopped in, and went for our "maiden voyage." As we got to about 40 mph, the front of the car began to shake/shimmy worse than I had ever experienced in any car I had ever driven. I thought, "Wow, something is REALLY wrong with this car!" I had never owned a convertible before, so I was not familiar with cowl shake. I did observe that the shake went away at about 50 mph and that the shake at 40-45 was much, much less with the top up.

After doing some reading, I learned about the vibration dampers that are supposed to be in all 4 corners of the car. The rears were missing. Got a pair at a junkyard, cleaned them up, painted and installed them. No difference.

One of my rear strut bushings was bad, and a club member gave me a set with good bushings (he had upgraded his to aftermarket ones). We changed those out at a club Tech Session. No difference.

One of the club experts said it could be something as simple as worn shocks. I thought, "Shocks are easy, I can replace those myself!" I replaced the front shocks and the Corvair specific front shock bushings. Maybe a very, very slight improvement...

Rotated the tires. No difference.

Changed the front sway bar bushings, which were bad. No improvement.

Changed the pitman arm bushing, which was bad. No difference.

Charged the rear stabilizer rod bushings, which were bad. No difference.

Saw that the rear shocks were leaking. Replaced those. No difference.

Had the tires balanced and checked for road force at a tire shop. He said the original steel wheels were not perfect, but that that was common. No improvement after wheel balancing.

My next item on the list for replacement was the front stabilizer rod bushings, which are clearly worn (not changed yet). Tie rod ends and ball joints seem to be good...

Then I noticed on another forum that someone was selling a set of 14" rally wheels with brand new tires.

I have always thought I would like to put a set of rally wheels on the car, mainly just because I like the looks, but I always thought that would be after all the other mechanical priorities were taken care of.

I decided to take the plunge and buy the wheels and tires (nice driver quality wheels). They are 195/70 x 14, which a tire comparison chart tells me is the same tire height as the 185/80 x 13s that were on the car. The new tires are definitely taller, which is fine by me.

Anyway, I installed the wheels and tires yesterday and took the car for a ride, and I can hardly believe the difference! The cowl shake at 40-45 is virtually gone! I really was not expecting such an improvement!

I still have a vibration that sets in around 60 mph, seems a bit better at 70, but it does not feel like cowl shake, it feels like a more typical wheel vibration. (Maybe those front strut rod bushings? Maybe wheel bearings?)

I must confess that I had really thought that I might not ever resolve the cowl shake, and I was ready to put the car up for sale in the spring and look for a coupe. Frankly, the car was just not pleasant to drive, and I want to be able to enjoy driving my car!

Well, now it is MUCH more enjoyable to drive (at least up to 60...) It's as if the car has been practically transformed. Now, the other things that it needs seem more reasonable to be able to tackle. I was reluctant to put more time and money into a vehicle that would never be enjoyable to drive due to cowl shake that I feared was just inherent to the design.

Was it the old tires or the old wheels? Not sure, although the old tires seemed almost brand new (Hankooks) when I bought the car. I suppose they could have been defective tires.

The good news is the car is much better. Every once in a while, it turns out to be something simple...

The "top down" testing will likely have to wait until spring unless we get an unseasonably warm Saturday sometime...

When time and money permit (hopefully in the spring), I would like to have a proper alignment done to protect those brand new tires and, of course to optimize the handling.

Regarding the car's new look vs. the stock wheel covers and whitewalls, the rally wheels with blackwalls make the car look SO much better--much more sporty, and frankly, masculine looking. Will try to post before and after pictures if we get a decent day to move the car outside for photos.

Gregg Birkholz
Canaan, CT.

1967 Monza 110 PG Convertible
2013 Chevy Malibu (Wife's DD)
1993 Cadillac Deville
2012 GMC Sierra 1500 Crew Cab
1997 Mazda Miata STO (Wife's fun car)
1989 Cadillac Deville (parts car)

Options: ReplyQuote
Re: Cowl Shake Finally (and unexpectedly) Resolved!
Date: November 05, 2017 04:09PM

Possible that the previous tires, though "balanced" were out of round.
Truing a set of tires to optimal center will make a difference, for sure.

You can jack up the front of the car and make a simple gauge that sits on the ground with a probe that nearly touches the tire. As you rotate the tire check to see if there is a variance in diameter.


Dan Davis ~ Pierce County, WA ~ CORSA Western Director + Corvairs NW + North Cascades Corvairs + Corvanatics
1966 Corsa Turbo coupe ~ ~ 1966 140 Corsa ~ ~ 1965 Monza 140/4 'Vert Sierra Tan/Fawn ~ 1964 Monza 'Vert (SOLD) ~ 1960 Monza Ermine White/Red PG ++ ~ 1965 Monza 140/4 Evening Orchid w/ ivory/black interior ~ 1962 Monza Wagon 102/4 ~ 1963 Rampside/Scamper ~ 1963 Red/Greenbrier ~ 1969 Ultra Van #468



Edited 1 time(s). Last edit at 11/05/2017 04:12PM by 1966-Corsa-GT-180.

Options: ReplyQuote
Re: Cowl Shake Finally (and unexpectedly) Resolved!
Posted by: MattNall ()
Date: November 05, 2017 04:20PM

Just happy you found it!

Must've been the Tires... as you moved the wheels with tires...

What pressures are you running in your tires?

Today most run 20 psi fronts / cold 30 psi rear / cold





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

Options: ReplyQuote
Re: Cowl Shake Finally (and unexpectedly) Resolved!
Posted by: eidolon ()
Date: November 05, 2017 04:33PM

When I got my 66 convertible, it had the same severe shake. The right front tire was 3/8 " out of round.
Replaced the tires and aluminum slots with stock hub-centric rims and quality tires; nothing but smooth rides (as the road allows).

Options: ReplyQuote
Re: Cowl Shake Finally (and unexpectedly) Resolved!
Posted by: gbirk1 ()
Date: November 05, 2017 04:46PM

Ran 32 psi rear and 22 psi front

Gregg Birkholz
Canaan, CT.

1967 Monza 110 PG Convertible
2013 Chevy Malibu (Wife's DD)
1993 Cadillac Deville
2012 GMC Sierra 1500 Crew Cab
1997 Mazda Miata STO (Wife's fun car)
1989 Cadillac Deville (parts car)

Options: ReplyQuote
Re: Cowl Shake Finally (and unexpectedly) Resolved!
Posted by: MattNall ()
Date: November 05, 2017 04:48PM

Those #'s are fine!





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

Options: ReplyQuote
Re: Cowl Shake Finally (and unexpectedly) Resolved!
Posted by: SoloCP ()
Date: November 05, 2017 04:59PM

I had the same problem with daughter Subaru. The tires even though had plenty of tread and appear to be very good shape had bad inner belts. Which caused vibrations at different speeds. Tire shop said not uncommon but can be a pain to determine as it is nothing visible and will not show up on balancing.


.

Don
Kansas City
HACOA
Broken Halo Corvair Garage.
61 Lakewood
62 Monza aka (Flicka)
62 Rampside
63 700 Sedan 3 Speed
64 Spyder Coupe (Bill Pierson Car)
64 Monza Convertible,140/4 Speed,Electric Heat,Kelsey Hayes Wheels
64 Spyder Blown, (Dave Bolduc Car)
65 Corsa 3.1 Liter Triple Weber (aka Unsafe)
66 Corvair V8 SuperVair (Created by Archibald Evans)
66 Avenger, Corvair Turbo, Fuel Injected, Air to Water intercool 140. (Michael Mann Car)
67 Monza 110 Auto. Sugar Bear

Options: ReplyQuote
Re: Cowl Shake Finally (and unexpectedly) Resolved!
Posted by: gnvair ()
Date: November 05, 2017 05:09PM

Radial run out on rims or tires can cause that. They will balance out fine but can cause horrible vibration or shaking. I saw this in a brand new set of Hankook tires on an Infiniti G37

Lee J

Options: ReplyQuote
Re: Cowl Shake Finally (and unexpectedly) Resolved!
Posted by: Brizo ()
Date: November 05, 2017 05:20PM

Are your door jamb wedges tight ? I didn't see them mentioned in your posts.

Dan Brizendine,
'64 8door Greenbrier 140 PG. "In beautiful Wanamaker Indiana...with one stop light and 5 pizza shops"

Options: ReplyQuote
Re: Cowl Shake Finally (and unexpectedly) Resolved!
Posted by: caroseiii ()
Date: November 05, 2017 06:33PM

Tires brick after a while.

Crawford

Options: ReplyQuote
Re: Cowl Shake Finally (and unexpectedly) Resolved!
Posted by: gbirk1 ()
Date: November 05, 2017 06:58PM

Door jamb wedges were supplemented to make the doors tight. Forgot that that was one of the things I did...

Gregg Birkholz
Canaan, CT.

1967 Monza 110 PG Convertible
2013 Chevy Malibu (Wife's DD)
1993 Cadillac Deville
2012 GMC Sierra 1500 Crew Cab
1997 Mazda Miata STO (Wife's fun car)
1989 Cadillac Deville (parts car)

Options: ReplyQuote
Re: Cowl Shake Finally (and unexpectedly) Resolved!
Posted by: red monza ()
Date: November 05, 2017 08:28PM

I had built a beautiful 55 ford f100 frame off...base coat-clear coat etc. Sometimes it would shake...not bad but noticeable.

One late evening I came back up the mountain from SC to home and it got a little chilly...the truck had been smooth as silk...I raised the pass side window about 2/3 up and the truck started its shaking...I rolled down the window...no shake....after that...it was all the way down or up when running interstate speed.

My friend with his new mustang years ago had a vibration....it was the floor board...ford banged in part of it and the vibration went away.

Options: ReplyQuote
Re: Cowl Shake Finally (and unexpectedly) Resolved!
Posted by: joelsplace ()
Date: November 05, 2017 09:56PM

I've got a Hunter road force balancer and there are a lot of different options on balancing. The standard one just does the best it can with weights which isn't much different than a standard balance. To take full advantage you have to dismount all the tires, spin the wheels, mark the wheels greatest imbalance point and 1-4, mount all the tires, spin them again and then it will tell you which tires to put on which wheels and the clocking of each tire. It can really make a big difference. I haven't had it long. I am curious to try it on one of my convertibles to see if it helps the cowl shake. None of them are bad but they do shake some at certain speeds on certain bumps.

Options: ReplyQuote


Sorry, only registered users may post in this forum.
This forum powered by Phorum.