Re: Welcome Keith Seymore

by dynchel Thu Oct 30, 2014 1:08 pm

IDK, iv'e researched this more times that i can remember. According to what i've read i should have all bases covered, yet the problem persists. I am really hoping these (traction bars) work. If not i can try keiths mismatched coil trick since i already own the coils to try it.

by dynchel Thu Oct 30, 2014 1:20 pm

Hey keith, l remember at CT you said you raced at thompson raceway park in thompson ohio. If you are out that way again let me know as that is about 45 minutes from me & i'd love to meet you and see your car in person.

by jerry46765 Thu Oct 30, 2014 2:22 pm

dynchel wrote:This is what they sell for coil spring cars.

Here's my copy prefitted.

From this picture, why does there appear to be a big gap between the rear tire and fender well lip?
Is the rear lifted with air shocks or high lift springs?

by dynchel Thu Oct 30, 2014 2:25 pm

It has station wagon springs in it, with 50 series tires.

by bracketchev1221 Thu Oct 30, 2014 6:27 pm

dynchel wrote:Mine will be done today, so i will (obviously) try them. My though is under load they will pivot againt the frame and force the rearend down. That would be the only way (i can figure) that they will work. I've had three different sets of rear tires on it (not drag radials just regular street tires)

They really only work if the rear of the car squats. A four link car generally doesn't have the rear pivot that a leaf spring car has. When the car squats, it is not actually planting the tire, but sucking it into the body. So those bars will hit the frame and redirect the force back into the tire.

by dynchel Thu Oct 30, 2014 6:31 pm

not what I want to hear.

by bracketchev1221 Thu Oct 30, 2014 6:44 pm

Keith Seymore wrote:
bracketchev1221 wrote:Keith, 2 questions are you still using the mismatched rear springs in the car with the stiffer spring in the passenger side, and what did you do to change the instant center? I am guessing that you modified the upper control arm mount, either front or rear of the bar.

Yes - station wagon spring on the RH side, with the production spring on the LH side. I also run an air bag in the right spring, usually preloaded at 20 psi.

For the instant center I relocated the upper control arm attaching holes at the forward location (in that main crossmember). I drilled new holes 1" lower than the production spot. That moves the instant center from the production location of 119.9" forward/18.1" up from the contact patch to 56.2" forward/15.9" up. I emulated the location I figured you would get from a set of anti-hop bars.

In "Alston Chassis" speak that takes you from a production setting of 43.7 Percentage of Rise to a new setting of 82.1 Percentage of Rise.

Ray - I'd like to hear more about the setup on your 70 Chevelle, either here or in another thread.

K

So you made your own "Trick Springs" cool. That is the way I would do it too. You have to get the lower bar flat and change the angle of the top bar. I ran the airbag in my 70 for a while and then put the Moroso springs in it. The mistake I made way back then was changing the angle of the bottom bar. It hit the tire hard, but too hard, and it wasn't productive. The best I went with the 10.5X29.5 tire and a 427 was 10.30's with a 1.42 60'. And then that motor broke a lifter and as they say the rest is history. Next came the 509 and the backhalf, and then I did it over into a 540. So currently its a ladder bar, 12 bolt rear, coil over setup. The motor is your average race gas, roller cam motor. 910hp/776 ftlbs. It's gone 9.03 at 148 and 1.26 60'. But now I have gotten a 76 for my next project, and I will apply the same stuff I learned over the years with the 70. I will try to make it hook and run in the 12's with a small block being a mild driver. Its funny when you have a 70 Chevelle, and it looks small in the garage compared to a 76!!!!! Really looking to talk to you about the drag racing part of it. I read part of your story about your dad's GTO. Great story, my dad ran in the Modified Production classes in the late 60's and early 70's before he gave up and went bracket racing. But my dad, running the A-body's as well gave me lots of the tricks they used back then when none of today's stuff was available. It is really cool stuff.

by bracketchev1221 Thu Oct 30, 2014 6:46 pm

dynchel wrote: not what I want to hear.

How stiff/soft is the front and rear? I am thinking, you need to soften the rear and let it squat but use a stiff shock, that controls the squat and doesn't allow it to start bouncing.

by Joe73 Thu Oct 30, 2014 7:02 pm

I dont think the traction bars are going to stop wheel hop. They are designed to stop or lessen axle rotation.

And I have to agree, there is alot of space between that tire and the wheel well lip. I always had plenty space in there as well. I ran competition engineering adjustable drag shocks front and back with no wheel hop. My rear shocks only extended 1 1/2 to 2 inches before they "topped out". I'm going with stock type heavy duty springs this time around.

Coil spring traction bars. I used to also have a pair in chrome but sold them.

Welcome Keith Seymore - Page 2 30wntdh

by bracketchev1221 Thu Oct 30, 2014 8:05 pm

Joe73 wrote:I dont think the traction bars are going to stop wheel hop. They are designed to stop or lessen axle rotation.

I think a solid or poly control arm bushing would do more to stop axle rotation than those do. The only rotation is due to bushing deflection. The other thing that MAY be happening and this is on a brainstorming level, (very small storm in my case) is that you are trying to plant the rear around 2 different locations. The MAIN point to plant the rear is the imaginary intersection point of the upper and lower rear control arms. Which is say for example, under the front seat. Now you try to apply force to the rear by the traction bar which is at a much shorter radius. It could be upsetting the MAIN intersect point and throwing off the leverage. But that being said, the traction bar would have to be hitting the frame.

by Joe73 Thu Oct 30, 2014 8:10 pm

And for what its worth, no poly on the diff housing. Just good rubber up there. Not enough give when the rear articulates with unequal length upper and lower arms.
Did alot of reading about the issue and the consensus is to use rubber above the diff. Even mentioned on the Ferd forums.

by bigredlaguna Thu Oct 30, 2014 8:13 pm

I've heard that the stock geometry GM 4 link suspension works better for drag racing when the car is sitting lower. Dynchel, If you can measure the geometry of your suspension, I bet that you will find the IC is way out in front of the car even more than factory ride height. You may want to simply lower the ride height and see if that helps. The top arms are shorter than the lower ones, so lowering the ride height effectively does the same thing as what Keith did by relocating the front mount point. The IC may not be as high off the ground, but at least it will be more centered fore/aft.

by bracketchev1221 Thu Oct 30, 2014 8:19 pm

Joe73 wrote:And for what its worth, no poly on the diff housing. Just good rubber up there. Not enough give when the rear articulates with unequal length upper and lower arms.
Did alot of reading about the issue and the consensus is to use rubber above the diff. Even mentioned on the Ferd forums.

Yes I agree, I ran rubber on the upper rear and solids on all others in my car as well. Way back when I did it, I didn't have anyone to ask. I just wanted to soften the hit on the factory ears. It made sense to me. I was just afraid of breaking the housing. But this setup went mid 1.40's in 60'.

by dynchel Thu Oct 30, 2014 8:39 pm

bracketchev1221 wrote:
Joe73 wrote:I dont think the traction bars are going to stop wheel hop. They are designed to stop or lessen axle rotation.

I think a solid or poly control arm bushing would do more to stop axle rotation than those do. The only rotation is due to bushing deflection. The other thing that MAY be happening and this is on a brainstorming level, (very small storm in my case) is that you are trying to plant the rear around 2 different locations. The MAIN point to plant the rear is the imaginary intersection point of the upper and lower rear control arms. Which is say for example, under the front seat. Now you try to apply force to the rear by the traction bar which is at a much shorter radius. It could be upsetting the MAIN intersect point and throwing off the leverage. But that being said, the traction bar would have to be hitting the frame.

I have poly bushings in fabricated arms. The upper is adjustable & has a pivot joint on the front. The traction bars aren't installed yet.

by dynchel Thu Oct 30, 2014 8:40 pm

Joe73 wrote:And for what its worth, no poly on the diff housing. Just good rubber up there. Not enough give when the rear articulates with unequal length upper and lower arms.
Did alot of reading about the issue and the consensus is to use rubber above the diff. Even mentioned on the Ferd forums.

I have a poly bushing on the rear end, but a pivot joint on the frame end.

by dynchel Thu Oct 30, 2014 8:43 pm

bigredlaguna wrote:I've heard that the stock geometry GM 4 link suspension works better for drag racing when the car is sitting lower. Dynchel, If you can measure the geometry of your suspension, I bet that you will find the IC is way out in front of the car even more than factory ride height. You may want to simply lower the ride height and see if that helps. The top arms are shorter than the lower ones, so lowering the ride height effectively does the same thing as what Keith did by relocating the front mount point. The IC may not be as high off the ground, but at least it will be more centered fore/aft.

The problem with lowering the ride height (which I would love to do)is the exhaust bottoms out now on speed bumps & dips in the road. Lowering it would just make the problem worse. Also my uppers are adjustable, I've tried two to make them shorter (to angle the pinion 2° down) and that didn't seem to help. I don't race it, I just like to do some burn outs once in a while (OK all the time lol)

by ant7377 Thu Oct 30, 2014 9:48 pm

Welcome! Love your car and the story behind it.

by Keith Seymore Fri Oct 31, 2014 8:20 am

Wow. You guys have been busy -

bracketchev1221 wrote: You have to get the lower bar flat and change the angle of the top bar.

This might be blasphemous but I'm not a huge adherent to emphasizing the bottom link must be level. My rationale is this: the Instant Center "is where it is"; said differently - it operates against the center of gravity of the vehicle based on its position regardless of how it gets there. With a full race car four link there are several configurations which would locate the IC in (roughly) the same position with varying degrees of control arm angle and they should all still respond in the same way.

My opinion on why there is a strong feeling for keeping the lower link level is because it allows you to make changes to the upper and move the IC fore/aft without changing the height. It sort of backs into the "make one change at a time" philosophy.

bracketchev1221 wrote:
Joe73 wrote:And for what its worth, no poly on the diff housing. Just good rubber up there. Not enough give when the rear articulates with unequal length upper and lower arms.
Did alot of reading about the issue and the consensus is to use rubber above the diff. Even mentioned on the Ferd forums.

Yes I agree, I ran rubber on the upper rear and solids on all others in my car as well. Way back when I did it, I didn't have anyone to ask. I just wanted to soften the hit on the factory ears. It made sense to me. I was just afraid of breaking the housing. But this setup went mid 1.40's in 60'.

With respect to control arm bushings I have solid bushings in the lowers; rubber in the uppers. My thinking is that the lower arm is in compression during launch; the upper is in tension, making it less critical and a reasonable place to allow some compliance without hurting anything from a performance perspective.

K

by dynchel Fri Oct 31, 2014 8:33 am

If you haven't already (Keith) check out the "my current project" thread for more on the subject.

by bracketchev1221 Fri Oct 31, 2014 6:18 pm

Keith Seymore wrote:Wow. You guys have been busy -

bracketchev1221 wrote: You have to get the lower bar flat and change the angle of the top bar.

This might be blasphemous but I'm not a huge adherent to emphasizing the bottom link must be level. My rationale is this: the Instant Center "is where it is"; said differently - it operates against the center of gravity of the vehicle based on its position regardless of how it gets there. With a full race car four link there are several configurations which would locate the IC in (roughly) the same position with varying degrees of control arm angle and they should all still respond in the same way.

My opinion on why there is a strong feeling for keeping the lower link level is because it allows you to make changes to the upper and move the IC fore/aft without changing the height. It sort of backs into the "make one change at a time" philosophy.

[quote="bracketchev1221

K[/quote]

I agree, but for many people it is easier to visualize with the lower bar level. Also I have had good luck with keeping the intersection point lower in the car than higher. it seems to apply a softer more consistent hit, than keeping it high in the car. High with my car, hit the tire very hard but it was not controlled. It was a shorter harder hit. This was kind of the reason I think the southside bars lost their novelty. Because the lower bar put the IC up and to the rear. The other thing I liked to have it parallel was just to keep the direction of force in line with the frame rail. Like you say, the lower bar is under compression, so it made sense to me to direct the force to the Frame where as bars pointing up would appear to put the force up into the body. Now I know its all vector forces and there are components that point in all directions, but I wanted the majority of the force forward and not upward. What is your opinion on this?

by Keith Seymore Mon Nov 03, 2014 8:53 am

bracketchev1221 wrote:

I agree, but for many people it is easier to visualize with the lower bar level. Also I have had good luck with keeping the intersection point lower in the car than higher. it seems to apply a softer more consistent hit, than keeping it high in the car. High with my car, hit the tire very hard but it was not controlled. It was a shorter harder hit. This was kind of the reason I think the southside bars lost their novelty. Because the lower bar put the IC up and to the rear. The other thing I liked to have it parallel was just to keep the direction of force in line with the frame rail. Like you say, the lower bar is under compression, so it made sense to me to direct the force to the Frame where as bars pointing up would appear to put the force up into the body. Now I know its all vector forces and there are components that point in all directions, but I wanted the majority of the force forward and not upward. What is your opinion on this?

I can't comment from experience on the hardness/softness of the hit with the various settings but - yes, I can agree with your theory.

K

by dynchel Mon Nov 03, 2014 6:22 pm

Keith Seymore wrote:
dynchel wrote:This is what they sell for coil spring cars.

I understand that they sell them; that doesn't mean they actually do anything performance wise.

K

Hey I got them installed... They work. Using the instructions I downloaded ( from Lakewood) I preloaded the right side (per the instructions) & they work...no more hop.

by Joe73 Mon Nov 03, 2014 6:55 pm

Glad they worked out.
I'd be careful when hitting any type of bumps with them. Especially preloaded. As soon as the rear suspension wants to compress, the bar will cause the axle to rotate pinion down. And the stress of this occurring will pull on your upper hein joint mount which would be the rebound bumper perch. That perch is pretty wimpy.

Anytime the snubber touches the frame and you add weight to the car (ie. additional persons) it will make the axle rotate pinion down and put a constant load on the perch.

Just FYI.

by dynchel Mon Nov 03, 2014 7:03 pm

By preloaded I mean they are touching the frame (RR) , not smashed against it. I thought the "bump stop" looked pretty beefy for its intended purpose. But thanks for the insite I'm just happy I got the wheel hop under control before putting her up for the winter. The car rarely goes more than 5 miles from home. (My job is 3 miles from home) the local cruise in in two miles away.

by Keith Seymore Tue Nov 04, 2014 8:47 am

dynchel wrote:[Hey I got them installed... They work. Using the instructions I downloaded ( from Lakewood) I preloaded the right side (per the instructions) & they work...no more hop.

I'm glad that worked out for ya'.

I'll tuck that bit of data away in my brain for future reference.

K

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