Suspension Notice for S/SS by NHRA

[Dyno]

Jeff, Email sent. Dan

[Jeff Lee]

This issue is really no different than the long-standing rule that allows for the replacement of biscuit rubber bushings with those of solid metal material such as aluminum or steel. Those applications include frame to body bushings in vehicles such as 1st & 2nd Generation Camaro's / Firebirds, Nova, etc. Why would NHRA allow for the replacement of those body bushings? Obviously NHRA understands these are race cars, not streets of New York street cars.

You have to ask what a rubber bushing is for on a vehicle. Is it something there to make the car function better (or worse) or is it something to do with ride harshness, vibration and functionality on various road conditions?
The body bushings obviously are made for ride and comfort compliance. NHRA allows the replacement of body bushings with solid metal bushings.

Strut rod bushings are no different. The are designed to flex under varying road conditions and provide isolation of the suspension from the rest of the vehicle. There is little, if any (I'm at a loss to think of any performance advantage), reason to replace strut rod bushings with some other attachment that does not use rubber bushings. There is a myriad of ways around the rubber bushings but the bottom line is; why would a racer eliminate the rubber bushing? It is simple. A more solid method of attaching the strut rod (which holds the lower control arm in compliance to the suspension travel), allows for better fore & aft control of the lower control arm from point "A" to point "B" of the drag-strip. This includes the movement from the starting line, wheel-stands if applicable, traveling the length of the track (and no track is lazer straight), and finally, hitting the brakes at the conclusion of the race. Obviously the most extreme focal points of the strut rod are wheelies and heavy breaking. Heavy breaking can be either to avoid a potential break-out Or in the instance of accident avoidance. Either way, the strut-rod bushing takers a beating. Obviously the results of heavy breaking and breaking a strut rod support will cause disastrous results to the vehicle. And quite possible the opponent and even the spectators.

Now, in the interest of the rule as presently defined, this leaves the racer with a few choices. He can use poly type bushings which are less compliant than OEM rubber bushings. This obviously will tighten up the front suspension and will most likely lead to less weight transfer. Ah Ha! That may be what your competitors are after and they most likely pushed for this rule "clarification". OK, a racer will get around that. He will go the old tried and true method of using an OEM style bushing and install it so loose it will hardly function. Now your competitor should be happy along with NHRA. But what have you created? You have created a race vehicle that is unsafe as the strut rod, if not secured properly may break; thereby loosing control of the vehicle. If nothing else, an improperly secured strut-rod will cause stability control issues.

Remember, none of these old strut-rod vehicles were designed as race cars with wheelies in mind, 130-150 MPH trap speeds, and heavy breaking at high speeds on skinny front tires.

To dictate a suspension must be OEM compliant when a racer is simply looking for a safer ride is unacceptable. The same argument applies to inner control arm bushings. The arguments before my post that NHRA requires OEM bushings is preposterous, NHRA requires OEM suspensions and that is not a dictation of methods of controlling those OEM suspension pieces. Again, the alternative to the purist argument is the installation of sloppy, cut-down OEM style bushings that are more effective than an OEM application for performance at the expense of an improperly controlled suspension used in an environment it was never intended for.

[Jeff Colvert]

Originally Posted by Jeff Lee

This issue is really no different than the long-standing rule that allows for the replacement of biscuit rubber bushings with those of solid metal material such as aluminum or steel. Those applications include frame to body bushings in vehicles such as 1st & 2nd Generation Camaro's / Firebirds, Nova, etc. Why would NHRA allow for the replacement of those body bushings? Obviously NHRA understands these are race cars, not streets of New York street cars.

You have to ask what a rubber bushing is for on a vehicle. Is it something there to make the car function better (or worse) or is it something to do with ride harshness, vibration and functionality on various road conditions?
The body bushings obviously are made for ride and comfort compliance. NHRA allows the replacement of body bushings with solid metal bushings.

Strut rod bushings are no different. The are designed to flex under varying road conditions and provide isolation of the suspension from the rest of the vehicle. There is little, if any (I'm at a loss to think of any performance advantage), reason to replace strut rod bushings with some other attachment that does not use rubber bushings. There is a myriad of ways around the rubber bushings but the bottom line is; why would a racer eliminate the rubber bushing? It is simple. A more solid method of attaching the strut rod (which holds the lower control arm in compliance to the suspension travel), allows for better fore & aft control of the lower control arm from point "A" to point "B" of the drag-strip. This includes the movement from the starting line, wheel-stands if applicable, traveling the length of the track (and no track is lazer straight), and finally, hitting the brakes at the conclusion of the race. Obviously the most extreme focal points of the strut rod are wheelies and heavy breaking. Heavy breaking can be either to avoid a potential break-out Or in the instance of accident avoidance. Either way, the strut-rod bushing takers a beating. Obviously the results of heavy breaking and breaking a strut rod support will cause disastrous results to the vehicle. And quite possible the opponent and even the spectators.

Now, in the interest of the rule as presently defined, this leaves the racer with a few choices. He can use poly type bushings which are less compliant than OEM rubber bushings. This obviously will tighten up the front suspension and will most likely lead to less weight transfer. Ah Ha! That may be what your competitors are after and they most likely pushed for this rule "clarification". OK, a racer will get around that. He will go the old tried and true method of using an OEM style bushing and install it so loose it will hardly function. Now your competitor should be happy along with NHRA. But what have you created? You have created a race vehicle that is unsafe as the strut rod, if not secured properly may break; thereby loosing control of the vehicle. If nothing else, an improperly secured strut-rod will cause stability control issues.

Remember, none of these old strut-rod vehicles were designed as race cars with wheelies in mind, 130-150 MPH trap speeds, and heavy breaking at high speeds on skinny front tires.

To dictate a suspension must be OEM compliant when a racer is simply looking for a safer ride is unacceptable. The same argument applies to inner control arm bushings. The arguments before my post that NHRA requires OEM bushings is preposterous, NHRA requires OEM suspensions and that is not a dictation of methods of controlling those OEM suspension pieces. Again, the alternative to the purist argument is the installation of sloppy, cut-down OEM style bushings that are more effective than an OEM application for performance at the expense of an improperly controlled suspension used in an environment it was never intended for.

Well said Jeff, The problem I had on my 3320lb car was trying to stop on a short track at 145mph. The stock rubber bushing would compress under the load of braking so much that the toe out on the front wheels would make the car unstable and try to hunt a place to go therefore taking up a lot of room between the wall and center line.The heim joint keeps the wheels in line all the time now.Looks like a safety issue to me.I think all the front suspension should be replaced with stronger aftermarket pieces.

[Dyno]

Jeff L., what you stated is what I sent to Jeff T., my concern is trying to maintain control of my car for my safety and the racer next to me. I spoke to two very will known chassis builders today and heard stories from them what happens with rubber mounted strut rods and braking on the end of a run, not locking the tires up, just trying to stop in a normal way. I hope NHRA looks at what they are trying to accomplish by this rule change. Dyno

[billy leber]

What is the benefit other than safety ? Nonsense.

[69Cobra]

Well said Jeff and Jeff LOL. I agree with both of you and I just realized what makes my car "hunt" in the shut down area. I still have the rubber bushings in mine and I was going to change them because I realized just how much the wheels move forward and rearward with the rubber bushings but I didn't realize it was toeing out under braking and that's why my car "hunts" I never understood that until now. Thank you.

I wish I was home to take a picture of the inside of the wheel housing on rear side by the firewall. I've always noticed that its always down to bare metal from the tire rubbing it. I would paint that area and after being out with the car once or twice it was polished shiny metal again. That's when I realized that the tires were moving that far back under braking and coming down off wheelies. I ordered the spherical bearing from Calvert to fix this issue. I hope NHRA understand that this is a SAFETY issue!!!

[SSDA Hemi]

Very well said!

1) trap speeds are over 160mph on AH cars.
2) You are going to require 7:50 sfi certs BUT want a passenger car front suspension??
3) The major advantage besides safety is looser front suspension/ increased travel- a high horsepower SS car does not need a looser front end.

[Larry Fulton]

IMO - With all of the other stuff that gets by, or what is now accepted as "Legal" in STK & SS nowadays this is nothing more than nonsensical BS, and looks only to give credence to someones job / position @ Glendora... They've gotta come up with something and this is it.

[Tom Nolan]

Safety should be NHRA's only concern for rule enforcement! However common sense doesn't always prevail. Strut rods with loose 48 year old rubber bushings or even new replacement bushings were never designed by the manufacturer to accelerate and stop like these cars do today. Just like drum brakes, the cars were unsafe so, disc brakes were added.
I'm sure you could find a spherical bearing on 99 % of the front suspension of vehicles competing in Stock and Super-stock. The shocks everyone uses has bearings on the mounting points. Does this mean we all have to go back to modifying stock shocks.....that should be safe? Anyone want to line up beside a new mustang going 150 plus mph then stepping on the brakes after he or she modified their stock struts? Yikes.

[69Cobra]

Hey guys, I'm home on R&R and I took some pics to show you how bad the rubber bushings let the tire/wheel move and interfere with the inner-fender well on my car. The car hasn't been out in 3 years so the bare metal looks a little rusty but when I was running the car regularly it was really shiny and polished looking. Anyways, I don't know how NHRA can not see that this is a safety issue. Not only is the interference/contact an issue but like Jeff C. said it allows the car to "hunt" in the shutdown area under hard breaking causing a toe out issue.

Drivers side


Passenger side