BMR Redesigns Lowering Springs for 4th Gen F-Body (SP001)
04-22-2009, 10:20 AM
#61
Thanks for your support.
BMR will continue to develop new products for all 5 generations of F-Bodies. We will also continue to improve and modify our existing products. Sometimes we will modify our existing product to improve for technical reasons and sometimes for marketing reasons. Either way, the F-Body community will have better products (and less expensive) to choose from.
BMR will continue to develop new products for all 5 generations of F-Bodies. We will also continue to improve and modify our existing products. Sometimes we will modify our existing product to improve for technical reasons and sometimes for marketing reasons. Either way, the F-Body community will have better products (and less expensive) to choose from.
BMR, just keep up the good work. you are no doubt one of the best companies to offer suspension parts for our cars. like i said a few pages back on this thread, your customers wanted you guys to make 1.25 lowering springs. so that shows they were already happy with the original springs and wanted just a bit more. and for you guys as a company to listen to your customers and to make the product says alot about you guys.
04-22-2009, 07:41 PM
#63
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I believe this question was already asked a page or two ago, but I didnt see any answers.
Thanks for your time.
04-23-2009, 12:15 AM
#64
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The new design offers both performance improvements and cosmetic improvements.
Performance:
When you lower the body another 0.25", you lower the center of gravity of the sprung weight by 0.25" also. Since the amount of weight transfer (body roll) from side to side is directly proportional to the cg height, you can reduce body roll by lowering the cg height.
Body roll is disruptive to the front suspension geometry. Rather than getting into a complicated discussion about negative camber gain, I'll just say that the size of the front tire contact patch gets smaller as the body rolls more. Bottom line: the lower the car, the better it handles.
Cosmetics:
This is a matter of personal preference, but most people agree that an F-Body looks better when it is lowered. Unfortunately, lowered F-Bodies are more likely to scrape the ground every time you hit a pothole or bump in the road. This was a compromise. We knew that we would lose some business to drivers that preferred a 1" drop. However, we felt that the majority of the market preferred a 1.25" drop.
Ride Characteristics:
We changed the rear spring rate from 170 pounds per inch to 160 pounds per inch. This should slightly improve the ride quality. But this is a small change. Most people couldn't tell the difference in a side-by-side driving test.
Weight:
A set of the new BMR springs are 8 pounds lighter than a set of the old BMR springs. As a matter of fact, the new BMR springs are slightly lighter than those other springs.
We look at the new spring design as a small improvement over the old spring design, but I wouldn't recommend that you replace your old BMR springs with the new BMR springs. The difference is too small to justify the cost.
Performance:
When you lower the body another 0.25", you lower the center of gravity of the sprung weight by 0.25" also. Since the amount of weight transfer (body roll) from side to side is directly proportional to the cg height, you can reduce body roll by lowering the cg height.
Body roll is disruptive to the front suspension geometry. Rather than getting into a complicated discussion about negative camber gain, I'll just say that the size of the front tire contact patch gets smaller as the body rolls more. Bottom line: the lower the car, the better it handles.
Cosmetics:
This is a matter of personal preference, but most people agree that an F-Body looks better when it is lowered. Unfortunately, lowered F-Bodies are more likely to scrape the ground every time you hit a pothole or bump in the road. This was a compromise. We knew that we would lose some business to drivers that preferred a 1" drop. However, we felt that the majority of the market preferred a 1.25" drop.
Ride Characteristics:
We changed the rear spring rate from 170 pounds per inch to 160 pounds per inch. This should slightly improve the ride quality. But this is a small change. Most people couldn't tell the difference in a side-by-side driving test.
Weight:
A set of the new BMR springs are 8 pounds lighter than a set of the old BMR springs. As a matter of fact, the new BMR springs are slightly lighter than those other springs.
We look at the new spring design as a small improvement over the old spring design, but I wouldn't recommend that you replace your old BMR springs with the new BMR springs. The difference is too small to justify the cost.
04-23-2009, 09:39 AM
#66
Performance:
When you lower the body another 0.25", you lower the center of gravity of the sprung weight by 0.25" also. Since the amount of weight transfer (body roll) from side to side is directly proportional to the cg height, you can reduce body roll by lowering the cg height.
Body roll is disruptive to the front suspension geometry. Rather than getting into a complicated discussion about negative camber gain, I'll just say that the size of the front tire contact patch gets smaller as the body rolls more. Bottom line: the lower the car, the better it handles.
But not changing the suspension pick-up point locations, specifically the panhard bar, actually increases the relative roll center, directly affecting weight percentages while turning.
While just lowering CG does help eliminate initial body roll, once inertia overcomes the roll center, the weight transfer is more abrupt. Ever heard of snap over-steer?
And because the PHB is in the rear, it moves the weight percentages forward. That's bad for an already nose-heavy platform. The front bites hard and the rear becomes light.
And I agree that the front tire contact will get smaller ... IF there is no sidewall deflection in the tire and your initial camber settings are somewhere around zero. I don't run solid rubber tires and zero camber, but maybe some one does.
It's a common misnomer that body roll is a bad thing. I disagree. Controlled body roll helps direct weight to the proper corner for maximum tire use.
My most recent experiments have seen spring rates approach 800 in the front and 250-275 in the rear (track dependent) using a 30mm/19mm sway bar setup.
There is more roll, but the front tires bite a lot better under braking and initial turn in and the rear tires hook a LOT better helping corner exit speed.
04-23-2009, 11:30 AM
#67
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Mitch,
I agree with what you are saying, that's just a little more technical than I wanted to get in my post.
Either one of us could write a huge post on the effects of weight jacking caused by lowering the body without changing the PHR pick-up points.
And imagine the size of the post if you wanted to discuss how to adjust front and rear roll centers to manage body roll and direct weight transfer to the proper corner. Heck, someone could write a book about it.
And yes, the front tire contact patch will only get smaller if the vehicle does not have any initial negative camber. But like I said in my original post, I didn't want to complicate the post within a negative camber gain discussion. It's a lot of fun to talk about, but I don't think that was the answer that Mystic was looking for.
Most BMR Lowering Spring customers are interested in Street Performance, not Road Racing or Autocross. Many BMR spring customers will Autocross their cars occasionally, but not full time. I try to keep this in mind when I answer tech questions.
Thanks for your input. I think this board needs more discussions about hardcore road racing and hardcore drag racing.
I agree with what you are saying, that's just a little more technical than I wanted to get in my post.
Either one of us could write a huge post on the effects of weight jacking caused by lowering the body without changing the PHR pick-up points.
And imagine the size of the post if you wanted to discuss how to adjust front and rear roll centers to manage body roll and direct weight transfer to the proper corner. Heck, someone could write a book about it.
And yes, the front tire contact patch will only get smaller if the vehicle does not have any initial negative camber. But like I said in my original post, I didn't want to complicate the post within a negative camber gain discussion. It's a lot of fun to talk about, but I don't think that was the answer that Mystic was looking for.
Most BMR Lowering Spring customers are interested in Street Performance, not Road Racing or Autocross. Many BMR spring customers will Autocross their cars occasionally, but not full time. I try to keep this in mind when I answer tech questions.
Thanks for your input. I think this board needs more discussions about hardcore road racing and hardcore drag racing.
04-23-2009, 11:58 AM
#68
So you guys dropped your old design and decided to copy a real spring, congratulations. I'm guessing the old springs just weren't cutting it anymore? Sales weren't where you wanted them to be? Your a fairly large company and I'm sure you have to make money to keep going. But, this means using a company to make your springs that has this quote on their website, "Aggressively pursue cost reductions and eliminate waste to provide profitability for future growth of our employees and the company." I am now full of confidence in what you have made 
I bought an aftermarket SS hood, a copy of the original, It was a huge mistake not buying the real deal. A waste of money. Good job trying to out do the little guy after they absolutely destroyed you guys for so long. Sorry to tell you that the people on this site aren't stupid and know exactly what you guys are doing.
I bought an aftermarket SS hood, a copy of the original, It was a huge mistake not buying the real deal. A waste of money. Good job trying to out do the little guy after they absolutely destroyed you guys for so long. Sorry to tell you that the people on this site aren't stupid and know exactly what you guys are doing.
04-23-2009, 12:49 PM
#70
Most BMR Lowering Spring customers are interested in Street Performance, not Road Racing or Autocross. Many BMR spring customers will Autocross their cars occasionally, but not full time. I try to keep this in mind when I answer tech questions.
Thanks for your input. I think this board needs more discussions about hardcore road racing and hardcore drag racing.
Thanks for your input. I think this board needs more discussions about hardcore road racing and hardcore drag racing.
This board has run off most the quality posters, because of differing opinions and the ensuing ****-storm. I'm in no way lumping myself in that category, other than having a different opinion. There is so much to know and learn.
But, I do know there is more than one way to get from point A to nirvana.
05-06-2009, 03:30 PM
#72
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BMR...quick question.
How would these new springs work with QA1's? I was debating getting the front QA1s sometime soon.
Everything on my car is BMR red, need to keep it looking the same!
How would these new springs work with QA1's? I was debating getting the front QA1s sometime soon.
Everything on my car is BMR red, need to keep it looking the same!
05-06-2009, 07:56 PM
#73
I have before pics, but no after pics. 
Was having the new BMR springs and Konis installed this morning when the front passenger side shock shaft (the rod with the threaded top) snapped in two.
Unfortunately, Koni can't get a replacement sent out 'til the 24th of this month. The shop had already done the driver side and had to take the new equipment off and put all the stock stuff back on. I can't let the car sit for over two weeks.
Was having the new BMR springs and Konis installed this morning when the front passenger side shock shaft (the rod with the threaded top) snapped in two.
Unfortunately, Koni can't get a replacement sent out 'til the 24th of this month. The shop had already done the driver side and had to take the new equipment off and put all the stock stuff back on. I can't let the car sit for over two weeks.
05-07-2009, 01:14 PM
#74
Mike, they will work fine with our springs. If you want to run our front springs instead of the QA1 springs all you need is our SA001 spring cups. They allow you to use a stock style spring on a coilover style shock. If you have any other questions let me know.
