Why not bumpers?
1 - 19 of 19 Posts
Joined
·
7,468 Posts
Welcome to the forum! These days, all cars have bumpers underneath their plastic front and rear fascias. It generally consists of an impact bar and some sort of energy absorbing material like Styrofoam. That way, the part of the bumper you see no longer has to look like a bumper. Maybe the Solstice just hides its bumpers better than other cars.
Hmmmm, I know cars need to have bumpers 
The soltice is a car under development (apperently complete) and the bumpers that are present are certainly not noticeable. If they are contoured immediately behind a rather pointy nose, then I doubt they are rigid (desirable no doubt). On the other hand if the bumper is in fact a rigid straight bar further back, toward the driver, then even a little front end collision will cause major damage until the bumber is reached.
So, not at all clear to me exactly what Pontiac did. Integrating the rear bumper I agree is not a problem. It's the front one that, to me, is intriguing. Had a Karman Ghia with the front bumper 'temporarily' removed, and promptly had a collision at less than 20 kph - don't remind me of the damage and cost to repair. I assumed that someone in the know might inform that eventually a 'nerve bar' type of bumper will be added.
-cheers
The soltice is a car under development (apperently complete) and the bumpers that are present are certainly not noticeable. If they are contoured immediately behind a rather pointy nose, then I doubt they are rigid (desirable no doubt). On the other hand if the bumper is in fact a rigid straight bar further back, toward the driver, then even a little front end collision will cause major damage until the bumber is reached.
So, not at all clear to me exactly what Pontiac did. Integrating the rear bumper I agree is not a problem. It's the front one that, to me, is intriguing. Had a Karman Ghia with the front bumper 'temporarily' removed, and promptly had a collision at less than 20 kph - don't remind me of the damage and cost to repair. I assumed that someone in the know might inform that eventually a 'nerve bar' type of bumper will be added.
-cheers
Joined
·
5,206 Posts
Having got a close look at the showcar firsthand, I can tell you that the structure pictures show pretty much what is going on wrt frt bumper.
There is a structural "beam" that goes between the rails, an expanded poly-propylene impact absorber (looks like styrofoam but MUCH stronger) and the fascia - that's it. In the french photos, you can see the bottom half of the energy absorber in the non-existent honeycomb grilles.
This strategy is actually quite common, and a number of cars use it. It's efficient, moderately low cost, lightweight (compared to the shock-like energy absorbers), durable (again, compared to the old shock-type e.a's), and re-impactable. To get cheaper, some energy absorbers are not even the styrofoam-like material, they look like a grate of plastic and are good for one hit at a given location - but like the expanded poly-pro, those systems are also backed up by a rigid bumper impact beam.
![]()
![]()
![]()
There is a structural "beam" that goes between the rails, an expanded poly-propylene impact absorber (looks like styrofoam but MUCH stronger) and the fascia - that's it. In the french photos, you can see the bottom half of the energy absorber in the non-existent honeycomb grilles.
This strategy is actually quite common, and a number of cars use it. It's efficient, moderately low cost, lightweight (compared to the shock-like energy absorbers), durable (again, compared to the old shock-type e.a's), and re-impactable. To get cheaper, some energy absorbers are not even the styrofoam-like material, they look like a grate of plastic and are good for one hit at a given location - but like the expanded poly-pro, those systems are also backed up by a rigid bumper impact beam.
Joined
·
7,468 Posts
Good illustration Solsticeman!
I just wanted to add that the plastic material used over the bumpers is also extremely flexible to resist damage on minor to lightly moderate impacts. It doesn't crack and break apart, and returns to its original shape. The paint still can crack, and it could spydercrack on impact. Also the plastic can tear if an impact is too harsh. But it should bounce right back if it is bumped in a parking lot or other similar mishap.
I just wanted to add that the plastic material used over the bumpers is also extremely flexible to resist damage on minor to lightly moderate impacts. It doesn't crack and break apart, and returns to its original shape. The paint still can crack, and it could spydercrack on impact. Also the plastic can tear if an impact is too harsh. But it should bounce right back if it is bumped in a parking lot or other similar mishap.
Joined
·
5,206 Posts
Correction: 3MPH.brentil said:
Bumpers and engine placement
Great inforamtion and pictures. many thanks! I guess like most others here, I can't wait to put down my deposit, and this type of inforamtion helps tremendously.
Another concern I have is a result of having owned a TR4A-IRS many (too many actually) years ago, and having it spin out on a curve on a 'slightly' wet road with 'slightly' worn tires within the first couple weeks of driving it. I wonder how good the Solstice's weight distribution has been - or can be made for that matter - made in view that it is not a mid-engine car. Or should we simply not expect the Solstice to be a 'well-handling' roadster?
- cheers
Great inforamtion and pictures. many thanks! I guess like most others here, I can't wait to put down my deposit, and this type of inforamtion helps tremendously.
Another concern I have is a result of having owned a TR4A-IRS many (too many actually) years ago, and having it spin out on a curve on a 'slightly' wet road with 'slightly' worn tires
within the first couple weeks of driving it. I wonder how good the Solstice's weight distribution has been - or can be made for that matter - made in view that it is not a mid-engine car. Or should we simply not expect the Solstice to be a 'well-handling' roadster?- cheers
Joined
·
535 Posts
Yeah, as Solsticeman mentions 3mph US, 5mph Canada. We lose out on that. No Mitsu Evo or a couple of other choices for me. :madbrentil said:
SM, I don't think I had noticed that picture earlier. I feel silly with this oversight, but with the amount of EPP in the grille area and the over all design I start to weep when considering FMIC location possibilities. I also wonder what system they will be using for headlamp mounting?
US Regulations ->used<- to be no damage from a barrier collision at 5 mph front and later 5 mph rear also, why GM went to the shelf bumpers in 1973. In 1983 this was reduced to 2.5 mph front and rear.
See http://www.nhtsa.dot.gov/cars/rules/regrev/evaluate/807072.html for a discussion and the actual requirements.
Basic rule is: don't hit anything.
See http://www.nhtsa.dot.gov/cars/rules/regrev/evaluate/807072.html for a discussion and the actual requirements.
Basic rule is: don't hit anything.
Joined
·
7,468 Posts
Manufacturers have gotten much better with roadsters weight distribution over the years. You will hear most front engine rear drive roadsters referred to as front-mid engine roadsters these days. Essentially, they get most if not all of the weight of the engine behind the front axle, distributing some of the weight to the back and balancing out the weight distribution.guenter said:Great inforamtion and pictures. many thanks! I guess like most others here, I can't wait to put down my deposit, and this type of inforamtion helps tremendously.
Another concern I have is a result of having owned a TR4A-IRS many (too many actually) years ago, and having it spin out on a curve on a 'slightly' wet road with 'slightly' worn tires
- cheers
On the Corvette, Chevy aids the weight distribution by putting the transmission at the rear axle instead of right at the motor. Adding the weight to the back from the front helps balance out the car. The Miata is another car with good weight distribution. One trick they use is putting the battery in the trunk. Both cars are extremely good handling roadsters, even with a front engine layout.
I expect the Solstice to be an equally good handling car. I doubt you will have to worry about any handling peculiarities.
Mid engine cars can get hairy on slippery roads too (and especially rear engine). With so much weight at the rear axle, it will step out very easily in slick conditions! The old Porsche 911’s were notorious for biting their drivers with the rear end coming around if they were overdriven. Porsche lovers feel it was part of the charm of the car, but it sometimes turned into a rather expensive charm!
Joined
·
5,206 Posts
quick comment, but "near 50/50" is as accurate as anyone (BMW, Mazda, Honda, chevy, pontiac, anyone) can get.
Most roadsters are around 51-53% front at curb, but passengers can shift the distribution on a typical roadster by 1-2% (YES, it's THAT much). The key here is seating position. Typical sedan passenger adjustments may only shift by a quarter or half percent. In other words, the passenger weight distribution can vary from 60% front for a 5 seat sedan to as low as 29% for a rearward seating position (think Lotus 7).
And the +/- 8 gallons of fuel have a direct effect generally on the rear weight and almost nil on the front weight (0% front, +/- 5%).
There's nothing magic about 50% either. Generally, anything lower than about 54% front at normal running condition (for some that may be 1- 145# driver, or for others it may be one 235# driver and 112# worth of safety equipment, or a 200# driver and a 115# passenger) has a very good chance of great handling qualities, depending on tuning and tire choices.
HAGD
Most roadsters are around 51-53% front at curb, but passengers can shift the distribution on a typical roadster by 1-2% (YES, it's THAT much). The key here is seating position. Typical sedan passenger adjustments may only shift by a quarter or half percent. In other words, the passenger weight distribution can vary from 60% front for a 5 seat sedan to as low as 29% for a rearward seating position (think Lotus 7).
And the +/- 8 gallons of fuel have a direct effect generally on the rear weight and almost nil on the front weight (0% front, +/- 5%).
There's nothing magic about 50% either. Generally, anything lower than about 54% front at normal running condition (for some that may be 1- 145# driver, or for others it may be one 235# driver and 112# worth of safety equipment, or a 200# driver and a 115# passenger) has a very good chance of great handling qualities, depending on tuning and tire choices.
HAGD
Joined
·
1,844 Posts
OK. True confession. Right now, sitting in the corner of my bedroom, is the front end of a '94 Camaro, that's been waiting too long to be painted. Makes for an interesting piece of "Car Art".
A few of years ago, my son drove into the side of a Grand Am with enough force to cause $3200 damage to their car. The Camaro's front "Tuperware" piece got a little tear and most of the paint jumped ship. It crushed the plastic eggcrate in front the real metal bumper that protects the radiator. He replaced this with styrofoam, put electrical tape on the tear and would regularly spray on touch up paint for the next couple of years. Now I plan on selling the car so I bought a new piece from RockAuto.com. Cost just $69! but had to pay $75 shipping 'cuz it's so big. Even though the thing is roughly 7'x3'x1', just put it on the bathroom scale and it weighed 11 pounds! Care to guess what the bumper and impact shocks on a '73 Riviera weighs?
A few of years ago, my son drove into the side of a Grand Am with enough force to cause $3200 damage to their car. The Camaro's front "Tuperware" piece got a little tear and most of the paint jumped ship. It crushed the plastic eggcrate in front the real metal bumper that protects the radiator. He replaced this with styrofoam, put electrical tape on the tear and would regularly spray on touch up paint for the next couple of years. Now I plan on selling the car so I bought a new piece from RockAuto.com. Cost just $69! but had to pay $75 shipping 'cuz it's so big. Even though the thing is roughly 7'x3'x1', just put it on the bathroom scale and it weighed 11 pounds! Care to guess what the bumper and impact shocks on a '73 Riviera weighs?
Joined
·
5,206 Posts
Mr. Wizard Lesson:
The weight distribution also has a lot to do with the "inclement weather" handling properties.
Front weight biased vehicles tend to understeer when in low traction situations, 50%-ers tend to drift and RWD versions may be more prone to throttle-steering, and Rear-Mid engine (45% front weight distribution or less) have a much greater propensity to acutally spin-out.
The explanation is simple: Limit understeer is largely determined by weight distribution and tire cornering stiffness. These are the dominant factors, with suspension kinematics and stiffnesses making up the remaining properties of understeer and transient steering behavior.
Lower the available traction, and the contribution of understeer by the tire cornering stiffness is reduced, making weight distribution the dominant factor.
The bottom line: in inclement weather, slow down! Yes, a Porshe or a Fiero will spin out way sooner than a Performance FWD car in similar low-traction conditions (and assuming they have similar dry handling properties). But only if you drive like an A#$HOLE :thumbs
The weight distribution also has a lot to do with the "inclement weather" handling properties.
Front weight biased vehicles tend to understeer when in low traction situations, 50%-ers tend to drift and RWD versions may be more prone to throttle-steering, and Rear-Mid engine (45% front weight distribution or less) have a much greater propensity to acutally spin-out.
The explanation is simple: Limit understeer is largely determined by weight distribution and tire cornering stiffness. These are the dominant factors, with suspension kinematics and stiffnesses making up the remaining properties of understeer and transient steering behavior.
Lower the available traction, and the contribution of understeer by the tire cornering stiffness is reduced, making weight distribution the dominant factor.
The bottom line: in inclement weather, slow down! Yes, a Porshe or a Fiero will spin out way sooner than a Performance FWD car in similar low-traction conditions (and assuming they have similar dry handling properties). But only if you drive like an A#$HOLE :thumbs
There are exceptions to every rule. The distribution on my Sunbird was about 65/35 (iron SBC in the nose of a Vega + a/c) yet it won a ->lot<- of autocrosses including state and divisional championships. By whole seconds (ask a serious auto-x'r what that means).
Why ? Great gobs of torque + LSD = AWS. Yes, it had monstrous understeer if you didn't get the tail out but it was always willing to wag.
![]()
Why ? Great gobs of torque + LSD = AWS. Yes, it had monstrous understeer if you didn't get the tail out but it was always willing to wag.
1 - 19 of 19 Posts
Join the discussion
