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Panhard rod points question


smokinjoe

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The B15 SE-R comes with a scott russell link, which is just a fancy name for a panhard rod. If I "replace" the SRL (below) with a real, honest and true panhard rod, I should only have to take +2 pts for the mod correct?

 

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Scott Russell, Watt's link, pan hard bar...... they all do the same thing, they just do it differently. They limit axle movement due to lateral forces. Some cars need them due to the design of the rear axle or the axle won't stay under the car during cornering. Are there benefits and disadvantages to one or the other, yes.

 

The main difference is 2 don't impart lateral displacement to the axle due to vertical movement of the suspension. Like a tie rod swinging through it's arch causing bump steer. Scott Russell and Watt's links don't cause lateral displacement, a pan hard does. A pan hard is the simplest and easiest to modify and tune.

 

Potato potato potato.

 

All we want to do is take the potato we already have and trade it for another type of potato. We already have a potato, we're not trying to add one.

 

And now it's time to finish cooking dinner, so I'll stop with the food analogies, lol.

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The B15 SE-R comes with a scott russell link, which is just a fancy name for a panhard rod. If I "replace" the SRL (below) with a real, honest and true panhard rod, I should only have to take +2 pts for the mod correct?
Scott Russell and Watt's links don't cause lateral displacement, a pan hard does.

OK, so it sounds like an "SRL" is actually a fancy name for a Watts link, rather than a Panhard bar. Is this correct?

 

For future reference, it will help if you list the specific rule from the TT classification forms, rather than just a points amount. A quick copy and paste of the particular rule will also help.

 

With that being said, I would see this particular situation falling under:

18) Replace or modify an OEM panhard rod or Watt's link +2

Mark

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I wouldnt see why it wouldnt fall under 18. It's a solid axle FWD car with a pair of trailing arms, without a panhard (SRL) there would be crazy, stupid lateral movement.

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they are all technically different due to how the mechanisms work, they all do the same thing though.

Just to clarify, while they basically "do the same thing," they are not necessarily identical in the eyes of the TT rules, based on this:

 

17) Add panhard rod or Watt’s link (regardless of whether the Watt’s link replaces an OEM panhard rod or not) +4
Mark
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If it makes you faster, I'm against it. It should cost a lot of points...

 

Kidding aside, thanks for posting the question. See you at CMP? (That's a drum I'm going to keep beating )

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I have never heard of a panhard rod on a FWD car. You've got a tough sell here, Joe.

If a FWD car has a non-independent "beam" rear axle (basically like an RWD live axle with the gears, diff, and axle shafts missing; just a way to hold the wheels and brakes on), then it will need a means of locating it laterally under the car. If the lateral location is not accomplished with a converging 4-link setup, then it will need something along the lines of a Panhard bar, Watts link, etc.

 

Mark

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800px-Scott_Russell_Linkage.jpg

 

57762894403396.png

 

this is a picture off the Scott Russell link (SRL) on a 2002 Sentra....... same set up that has been run since 1995 up until 2006.

 

w/o something to maintain lateral stability of the rear axle the trailing arms and struts would be the stress bearing members and they would fail post haste. The SRL bears the lateral stress. Same thing a Panhard or Watt's does. A Watts link is named after the same guy an electrical Watt is named after, SRL probably some guy named Scott Russell. Different ways to skin a cat. Neither a SRL or WL causes much lateral displacement of the axle as the suspension travels up and down and as such in some applications is viewed as superior because of it. On a pan hard set up the axle will displace as the Panhard rod swings through it's arch, but that effect is mitigated as the bar's length increases. So because of space constraints and/or shying away from 1940's technology a Watt's or SRL gets throw in the mix on modern FWD cars w/ a dead rear axle most of the time.

 

 

If you look at the exploded view, w/o the 2nd link inside the major link, with an attachment point on the axle and another on the chassis, a SRL would essentially be a panhard bar. The major difference is the bushing attaching to the axle is designed deflect about 3/4 of an inch in either direction instead of the axle displacing, that's the major design feature that distinguishes it as a SRL. NONE of the bushings in the rear suspension of Joe's car were designed to run with racing slicks or the lateral forces the car currently generates. There are NO aftermarket replacements and due to the design of the funky deflecting bushing attaching to the axle I can't think of a way to fabricate anything that will retain the correct functionality of the SRL as designed to technically keep it a SRL. The car destroys the bushings and the dynamics of the car get unpredictable when they go.

 

I could whip up a Watt's or Panhard in a weekend but I can't figure out how to keep the SRL from chewing up bushings. I've thought of just throwing a rod from the axle attachment point to the chassis attachment point, essentially converting it to a panhard, but the short length of the rod would cause too much lateral displacement as the suspension travels up and down.

 

The car already has a device to maintain lateral stability of the rear axle, it won't work w/o one, we just want to trade one for another. There is no mention of SRL anywhere in the rules. So what can we classify a SRL as??? Do we take 2 or 4 points?

 

17) Add panhard rod or Watt’s link (regardless of whether the Watt’s link replaces an OEMpanhard rod or not) +4

 

18) Replace or modify an OEM panhard rod or Watt’s link +2

 

P.S. I'm building a new car from the ground up for 2012, so the FWD Nissan beat downs are going continue regardless

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It seems to me that an SRL functions in the same manner as a Watts link. So, per my interpretation, going from an OEM Watts to a non-OEM Panhard would be:

18) Replace or modify an OEM panhard rod or Watt's link +2

If you were going from an OEM Panhard to a non-OEM Watts/SRL, then I would interpret it to be:

17) Add panhard rod or Watt’s link (regardless of whether the Watt’s link replaces an OEM panhard rod or not) +4

Mark

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Once Greg chimes in I'll prep for surgery

 

So would it be +4 to go from a SRL to a Watt's, or +2? It seems like the consensus is a SRL and a Watt's are more alike than a panhard and an SRL.

 

I don't have a preference, but from a coolness and challenge standpoint, a Watt's link would be more satisfying to build.

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17) Add panhard rod or Watt’s link (regardless of whether the Watt’s link replaces an OEM panhard rod or not) +4

18) Replace or modify an OEM panhard rod or Watt's link +2

My not-Greg interpretations:

 

SRL = Watts

Watts > Panhard

SRL > Panhard

 

If you install a non-OEM Panhard bar on a car that didn't have a locating device, then you would pay +4 per #17.

If you install a non-OEM Watts link on a car that didn't have a locating device, then you would pay +4 per #17.

If you replace an OEM Panhard bar with a non-OEM Watts link, then you would pay +4 per #17.

If you replace an OEM Panhard bar with a non-OEM Panhard bar, then you would pay +2 per #18.

If you replace an OEM Watts link with a non-OEM Watts link, the you would pay +2 per #18. This appears to be what Hired Wrench wants to build per his post above.

If you replace an OEM Watts link with a non-OEM Panhard bar, then you would pay +2 per #18. This appears to be Joe's situation per his original question.

 

Mark

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I have never heard of a panhard rod on a FWD car. You've got a tough sell here, Joe.

 

Agreed. Not many FWD cars are saddled with a solid rear axle. Although the Scott Russel Link can be intrepreted as a watts link, I'm asking for the lesser panhard "replace" points option at +2 to control lateral movement.

 

 

Mark, your assessment is correct for me.

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If it makes you faster, I'm against it. It should cost a lot of points...

 

Kidding aside, thanks for posting the question. See you at CMP? (That's a drum I'm going to keep beating )

 

We probably wont have the panhard done by CMP, and even if we do - it's all just a work in progress. You, Skip and Robert are the kings on TTB. I'm just along for the ride

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We probably wont have the panhard done by CMP, and even if we do - it's all just a work in progress. You, Skip and Robert are the kings on TTB. I'm just along for the ride

 

So I take that to mean you'll be at CMP, continuing to destroy SRL bushings, right? Wouldn't be the same w/o the TTB Sentra.

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If we can get a consensus from Greg that the SRL is a panhard, we'll start work after Barber. So maybe, we'll have it for CMP but it wont be dialed in so I dont expect much change. Right now it's "pitch the car, wait for the chassis to flex and wait for the outside front wheel to bite" It's a frustrating experience now that the speed is a little higher than it was in TTE.

 

I'll be holding up the back up the pack in TTB. I'm just here to help you with the contingencies

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It really does function and look more like a Watts link than a panhard rod/bar. I've discussed it with JWL, and we are both ok with you considering it to be an OEM Watt's link, and proceed from there. So, it sounds like +2 for the aftermarket part.

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