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Engine Mount Failure Shakes Oldsmobile

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bandaid
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Iron
Re: Ah, Yes, the V-8 Corvair
bandaid   3/1/2012 9:43:07 AM
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Sounds like you had quite the corvair! I love mods like that. would love to see pictures of the shoehorn you used to put the SB in there.

bandaid
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Iron
Mount Failure
bandaid   3/1/2012 9:39:00 AM
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I had a 89 Thunderbird Super Coupe that had Fluid filled motor mounts. They are known for failure because the tourque of the supercharged engine will tear them up rather quickly. Unfortunatly, when they do fail, they let the oil pan rest on the crossmember which will eventually rub through and cause futher problems. I guess every vehicle has their problem huh. Now every time I change the oil on ANY of my cars I check the motor mounts.

David12345
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Platinum
Re: The Vega Aluminum Block
David12345   3/1/2012 8:28:07 AM
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My understanding is that the Vega was using an innovative high-silicon content aluminum block without steel sleeves (Except the Cosworth Version Engine).  I'm not sure about block warping problems worse than other engines machined from fresh castings; however, the Vega definitely had more issues with cylinder wear until the rings were no longer sealing well, with the resultant burning lots of oil.

Charles Murray
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Blogger
Re: Ah, Yes, the V-8 Corvair
Charles Murray   2/29/2012 11:27:34 PM
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David12345: It's not hard to find people who restore Corvairs, and there must be a good reason why that restoration market has continued successfuly for four decades. Regarding the Vega: Wasn't that the one that used an aluminum cylinder block? Didn't the block have warping problems?

David12345
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Platinum
Re: Ah, Yes, the V-8 Corvair
David12345   2/29/2012 6:48:18 PM
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I tend to challenge engineering done by an attorney trying to make a name for himself (Ralph Nader).  His book "Unsafe At Any Speed" came out in 1966 after the handling problem was virtually fixed, and was full of questionable evaluation and conclusions.  Like most believable lies, it had just enough truth to be difficult to challenge.

Positive Camber:

The early Corvairs from 1960 to 1963 had swing arm suspensions which could travel into positive camber causing weight jacking, but so did Porshe, VW, Lotus, and Corvette among others.  From my observations, the VW Bug and VW Bus had far worse handling problems in this area than any of the others.

In 1964 Corvair added a suspension component that limited the down travel and potential negative camber.

From 1965 to 1969, the Corvair had a full independant rear suspension which virtually eliminated the issue.  Corvette made this upgrade around the same time. Later on, Porshe and VW made these upgrades as well.

Rearward Weight Bias:

The stock Corvair had a rearward 30/70 weight bias that could create oversteer, which the typical driver is unprepared to deal with.  So did VW Bug, VW Bus, Karman Ghia, and Porshe.  Chevrolet largely tuned-this-out of the Corvair with a very low front suspension roll center design, a very stiff front sway bar, and specified low front tire pressures. This car actually had more understeer than preferred for best race handling. It could still transition to oversteer in poor traction turning conditions such as snow, ice, or sand. Naturally other cars have trouble in these conditions with poor driving techniques as well.

My V8 Corvair was mid-engine with about a 40/60 weight bias.  If I moved the radiator to the front it would have been about 55/45 to 50/50 weight bias depending upon my final engine relocation.  I had slightly stiffer springs for stock ride height even with more weight, I also had had wider tires in the rear for a balanced tire contact patch and horsepower to the ground. I also added a rear sway bar.  This car was VERY stable and did well in the snow (unusual for a muscle car). The car still had more understeer than desired and ideally needed closer to neutral quick-transition handling by a stiffer rear sway bar, a softer front sway bar, adjustable racing shocks, and new upper A-arms for a higher front roll-center.  I would joke that my Corvair was "Unsafe at Every Speed" because it could get to speed so quickly, but it was actually very safe.

Exhaust Fumes in the Car:

The heater on air cooled engines could pump oil or exhaust fumes into the car.  This was true of VW, Porshe, Corvair, and others.  This was worse by oil leaks from Butyl rubber O-rings on the Corvair push-rod tubes. Enthusiasts later determined that Viton O-rings effectively fixed this problem.  Naturally, other oil or exhaust leaks, would need to be fixed to avoid this problem.

My Corvair had a SB Chevrolet V8 water-cooled engine with a 1967 Mustang heater mounted to the cowl below the windshield; so, this extra risk of exhaust fumes was a moot concern for my application.

Corvair Discontinued:

Through the years the Corvair model was successfully raced by the Yenko Team and others with exceptionally good handling.  I believe that Corvair was killed by the economics of manufacture, and the fact that it did not fit into the Chevrolet portfolio of products, NOT legitimate safety issues.  The stripped-down economy end was better handled by Vega, Monza, and others to compete with Ford Falcon and Pinto.  The marketed performance banner was to be carried by Corvette and Camaro with more horsepower than even the 180 hp turbocharged Corvair.  The marketing of the Corvair was also damaged by Ralph Nader, so the "American Porshe" was discontinued.

 

dmorgan
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Iron
me, too
dmorgan   2/29/2012 6:18:22 PM
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I had the mounts on my dad's 66 Impala break in the middle of town at a stop sign. Main problem was, I had my Mom with me & I was 17! Throttle hung wide open scaring the fool out of me & Mom.Years later I had another 66 Impala,  an SS 300hp 327. I broke several until GM recalled all models including Dad 69 Impala. The "fix" was a short cable with bolts that went from the head to the frame. Dad used the cable, I found some solid mounts at a Speed Shop.

David12345
User Rank
Platinum
Re: Scary problem
David12345   2/29/2012 5:58:54 PM
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At least the V8s usually were cradled on the front suspension in such a way that the forward and back movement of the engine and transmission seemed to be limited by exhaust systems, block shape, oil pan, and bellhousings nestled between the firewall and the cross-frame members.  Forward and back, the worst I ever saw was a radiator "decored" by the fan and engine pulleys. The engine torque on the other hand could have the engines get positively UNGLUED. The misalignments could take-out drive shaft U-joints or unplug the spline from the back of the transmission.

Buddies that modified thier engines for more horsepower and raced them at the track often installed chains or metal turnbuckles at the front of the engine to limit travel. This chain was the cheaper recall fix that GM chose in the 1970s before the improved motor mounts came from the factory.  The more serious racers would go to solid metal mounts or front plate mounts, but that added a whole new dimension to the vibration in the car.

I don't believe GM did the more standardized factory engines across marques until the later 1970s after the beefed-up mounts were standard equipment.  Even then, I believe there were many unique engines to Cadillac, Pontiac, Oldsmobile, and Chevrolet until the V6s became more common.

bob from maine
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Platinum
Engine Mounts
bob from maine   2/29/2012 1:20:11 PM
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During the 60's and 70's when US manufacturers offered big, high torque engines, the standard bonded steel-rubber-steel mounts had a tendancy to de-bond. After some un-planned engine departures, the manufacturers started making interlocked or caged engine mounts where rubber separated the steel parts and isolated noise but prevented excessive engine movement in case of failure. Today, unplanned departures seldom occur but the bonding process to attach rubber to metal hasn't improved much. In my experience, a significant percentage of high-mileage cars and pick-ups have one or more faulty engine mounts. Leaking oil, road salt, solvents, phase of the moon all seem to cause debonding. Many suspension components are also steel-rubber-steel and debonding of them is an issue. Auto manufacturers have done well to engineer mounting assemblies that continue to work safely even after wear, rust and chemical decomposition have taken their toll.

ChasChas
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Platinum
Déjà vu
ChasChas   2/29/2012 11:02:10 AM
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I had this problem with my 1963-1/2 Ford Galaxy. It was after that that I noticed that engine mount were made with the metal interlocking and the rubber between. The rubber could fail and the metal would still hold it.

Why would they have to learn this thing all over again?

Déjà vu all over again - Yogi would say.



OLD_CURMUDGEON
User Rank
Platinum
Seems to me .....
OLD_CURMUDGEON   2/29/2012 10:56:37 AM
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IF memory serves me, GM had a VERY serious problem w/ engine/transmission mount failures several decades ago.  So much so that the gov't really came down hard on them as they continued to deny warranty claims & out-of-warranty claims for defective mounts.  It was an across-the-biard problem, affecting just about every make & model from Chevrolet to Cadillac.  Could it have been in the era when GM was cross-populating their vehicles with engines from their sister divisions?

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