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Portmod7 · 10-05-2010, 03:17 PM

I was going to ask if anybody had tried the H kit. I stumbled onto it a couple months ago and it sounded pretty sweet. Pricy, yes. But you know what they say, how fast do you want to go? Although, its very hard to know if you're getting the speed you pay for unless you can buy the whole gammot of options and do some testing.

I have been thinking long and hard on what to do in the rear of my truck, as far as lateral location of the rear goes. Yes, a panhard bar is simple, and NASCAR uses it, but NASCAR also only turns in one direction most of the time. I can't seem to convince myself that a panhard bar will NOT cause the vehicle to act differently in a RH turn compared to a LH turn. Depending on which end is mounted to the frame, which end is mounted to the housing, and which direction you intend to turn, it seems like there would be a separate preferred mounting orientation for each turn direction.

If the P-bar is mounted to the frame on the D-side, housing on the P-side, and you make a LH turn, the body will pivot and roll to the right. In my head, it seems like the body would pivot at the frame mount of the P-bar which is a LONG way from the RR spring, generating the majority of the roll-stiffness to the right at the RR spring. The body and CH would also "climb" around the housing mount. With the same P-bar orientation, a RH turn would cause the body to roll about the frame mount to the left, causing the CG to "climb" up and around the frame mount. It seems like the roll stiffness to the left would come from from the CG trying to "climb" because the pivot is located so close to the spring. But I suppose as it tries to climb, it will load the LR as the CG moves more to the left and above the LR spring. I'm not sure I'm anywhere in the ballpark with any of that?

So I guess my question is: Is the dynamic loading on the LR spring in a RH turn the same as the dynamic loading on the RR spring in a LH turn with a P-Bar? Also I have concern with the "radial deflection" mentioned above. Even with a long bar, it's still a factor.

A watts-link would cure radial deflection. I invision one mounted horizontal, either above or below the housing. Although, either position presents mounting/clearance challenges. My question about a watts-link is: where is the RC? It seems like the lateral location would be at the center pivot, on the housing. But what about the horizontal location? Would it be at the center pivot on the housing, or at the height of the mounting points of the links at the frame, or a combination of the two?

The watts-link, as I have suggested it, is a bummer because I'd either be mounting it above or below the housing, and moving it to one or the other will make a HUGE difference in handling. It would be really hard to tune. You could mount it vertically behind the housing, but it seems like it would deliver inconsistant handling from RH to LH turns because of the necessary difference in height of the link mounting points at the frame.

So anyway, sorry for writing a "novel". Suspension geometry intrigues me. I am a race car driver. I work on my own cars, I am my own crew/car chief and mechanic. I get to make suspension adjustments every week trying to go faster. It doesn't always work the way you think it should. I am also a mechanical engineer by profession, so that helps me understand a little more where common sense fails me. I was just looking for some friendly discussion on the topic.

Thanks for posting all the great information!

10-05-2010, 03:17 PM	#119
Portmod7 Registered User Join Date: Dec 2004 Location: Aztec, NM Posts: 388	Re: Make it handle I was going to ask if anybody had tried the H kit. I stumbled onto it a couple months ago and it sounded pretty sweet. Pricy, yes. But you know what they say, how fast do you want to go? Although, its very hard to know if you're getting the speed you pay for unless you can buy the whole gammot of options and do some testing. I have been thinking long and hard on what to do in the rear of my truck, as far as lateral location of the rear goes. Yes, a panhard bar is simple, and NASCAR uses it, but NASCAR also only turns in one direction most of the time. I can't seem to convince myself that a panhard bar will NOT cause the vehicle to act differently in a RH turn compared to a LH turn. Depending on which end is mounted to the frame, which end is mounted to the housing, and which direction you intend to turn, it seems like there would be a separate preferred mounting orientation for each turn direction. If the P-bar is mounted to the frame on the D-side, housing on the P-side, and you make a LH turn, the body will pivot and roll to the right. In my head, it seems like the body would pivot at the frame mount of the P-bar which is a LONG way from the RR spring, generating the majority of the roll-stiffness to the right at the RR spring. The body and CH would also "climb" around the housing mount. With the same P-bar orientation, a RH turn would cause the body to roll about the frame mount to the left, causing the CG to "climb" up and around the frame mount. It seems like the roll stiffness to the left would come from from the CG trying to "climb" because the pivot is located so close to the spring. But I suppose as it tries to climb, it will load the LR as the CG moves more to the left and above the LR spring. I'm not sure I'm anywhere in the ballpark with any of that? So I guess my question is: Is the dynamic loading on the LR spring in a RH turn the same as the dynamic loading on the RR spring in a LH turn with a P-Bar? Also I have concern with the "radial deflection" mentioned above. Even with a long bar, it's still a factor. A watts-link would cure radial deflection. I invision one mounted horizontal, either above or below the housing. Although, either position presents mounting/clearance challenges. My question about a watts-link is: where is the RC? It seems like the lateral location would be at the center pivot, on the housing. But what about the horizontal location? Would it be at the center pivot on the housing, or at the height of the mounting points of the links at the frame, or a combination of the two? The watts-link, as I have suggested it, is a bummer because I'd either be mounting it above or below the housing, and moving it to one or the other will make a HUGE difference in handling. It would be really hard to tune. You could mount it vertically behind the housing, but it seems like it would deliver inconsistant handling from RH to LH turns because of the necessary difference in height of the link mounting points at the frame. So anyway, sorry for writing a "novel". Suspension geometry intrigues me. I am a race car driver. I work on my own cars, I am my own crew/car chief and mechanic. I get to make suspension adjustments every week trying to go faster. It doesn't always work the way you think it should. I am also a mechanical engineer by profession, so that helps me understand a little more where common sense fails me. I was just looking for some friendly discussion on the topic. Thanks for posting all the great information!