It was a disappointing day really. Not just the fact that I got beat off the line by a Fiero, but If you watch the video you'll see I backed off real early. Watch my head and the car in relation to the horizon. See how much I'm bouncing around. At first I couldn't figure out what was going on. Was it a high speed stability issue, alignment? So I took a run in my son's Mustang and figured it out. The runway has dips in it. You could hardly notice it in the Mustang but the GTM was bucking like a Bronco!
I have LSman's swaybar, Genesis shocks 350# front 650# rear coilovers.
Opinions, ideas?
I'll have to look at my gear chart tomorrow to figure out how fast I was going before I backed out of it. Looks like 5400 rpm in 5th.
Anyway, I think the fastest car was a ZR1 that ran 179.
Awsome man.. thanks for the summary. Yeah I see what you mean with the boucing around in the video... I would guess thats gonna be a shock setting issue. Some shocks are adjustable and some are just set a certain way with rebound stiffness and it can get VERY complicated on what works the best.
Check out this link
click on "VALVING" and you will see just how many options "racers" are faced with deciding on what will work best... what a headache. They do make a really expensive set of shocks that have a knob on them that you can set your stiffness with.. so my guess is you can either find someone who has tried them all and knows what works best or fork out for the expensive set and turn the knob hopeing to feel a difference. Ive never been very good at whats best for what either though ....
It was a disappointing day really. Not just the fact that I got beat off the line by a Fiero, but If you watch the video you'll see I backed off real early. Watch my head and the car in relation to the horizon. See how much I'm bouncing around. At first I couldn't figure out what was going on. Was it a high speed stability issue, alignment? So I took a run in my son's Mustang and figured it out. The runway has dips in it. You could hardly notice it in the Mustang but the GTM was bucking like a Bronco!
I have LSman's swaybar, Genesis shocks 350# front 650# rear coilovers.
Opinions, ideas?
I'll have to look at my gear chart tomorrow to figure out how fast I was going before I backed out of it. Looks like 5400 rpm in 5th.
Anyway, I think the fastest car was a ZR1 that ran 179.
Was that your first time at the track with the car, it looked l like he got the hole shot but you passed him fairly easy. How fast is the mustang?
Did you ever run the car with the original konis? It would be interesting to see if there is a difference in the bouncing and stability, between the yellow,black koni and the shocks you have on , also what are your alignment settings at, tires and air press. It would be valuable information for all, in how to set their suspensions.
watching the time and the runway... looks like you ran about a 13.5-14 second quarter mile.... I would call that babyin it !
1st gear I was about 1/2 throttle, second gear you can here when I firewalled it. So yes I was babyin it. I was going just over 140 when I backed out of it. So I think on a smooth surface I could be up around 155 in the 1/2 mile, maybe a little quicker if I start off in second. Keep in mind I have an LS1 putting about 410 HP at the tires. You guys with big horsepower could run some remarkable numbers if you can get the power to the ground.
I'd just like to find a solution to the violence going over the bumps. I couldn't get those pictures of that GTM in Texas after he swapped ends out of my mind...
Mike
Yes that was the first time I had it on a high speed track. The Mustang is just a stock GT so not very quick.
I had the car up to about 150 with the original black Koni's and springs. It was a little twitchy. I'm sure on that same road with the new setup would be fine. I have about 2.5 deg of castor, 1/8" toe in front and rear. I don't recall the camber setting and I was running 26# front, 24# rear in my PS2's
I know the exact feeling you are talking about when driving in the mid 100s. It's a white knuckle ride for sure. We have the sway bar but still running the stock black koni shocks inverted. I was hoping that swapping the shocks and springs with what LSMAN sells would minimize the twitchy feeling. But it sounds like you are running what we are working towards. Keep us up to date with what you do to overcome the twitchy sensation.
Congratulations on bringing the car home in one piece. Any time you can do that, it's a good day.
I know the exact feeling you are talking about when driving in the mid 100s. It's a white knuckle ride for sure. We have the sway bar but still running the stock black koni shocks inverted. I was hoping that swapping the shocks and springs with what LSMAN sells would minimize the twitchy feeling. But it sounds like you are running what we are working towards. Keep us up to date with what you do to overcome the twitchy sensation.
Congratulations on bringing the car home in one piece. Any time you can do that, it's a good day.
I was hoping the shock, spring, swaybar combo would do the trick as well. I also added the AGR 165 power rack and MR2 pump to the mix. This setup has a stiffer ride than the stock setup even though I have softer springs on all four corners. Also the tires will contact the swaybar before I reach full lock in both directions.
If I were to guess just based on observations of my car (keep in mind I have no background in racing or suspension setup) the stock setup is over sprung and under dampened. My current combination is probably over dampened and maybe over sprung still. I'm not crazy about being Goldilocks in search of the perfect mix, but here I am.
Keith
well my bet is still on it being in the steering ... it so responsive that above 100 it feels like you start riding on the edges of the tire instead of the flat part and as you minutely make corrections something is amplifying it in the rear and causes an uneasy feeling in your stomach and the only correction is to focus on steering SLOWLY....
iron.man,
I agree the steering is very sensative. I kow when I first started driving the car I was putting too much input to the wheel. You can see in the video I put my elbow on the arm rest to limit the steering motion to just my wrist.
I was hoping the shock, spring, swaybar combo would do the trick as well. I also added the AGR 165 power rack and MR2 pump to the mix. This setup has a stiffer ride than the stock setup even though I have softer springs on all four corners. Also the tires will contact the swaybar before I reach full lock in both directions.
If I were to guess just based on observations of my car (keep in mind I have no background in racing or suspension setup) the stock setup is over sprung and under dampened. My current combination is probably over dampened and maybe over sprung still. I'm not crazy about being Goldilocks in search of the perfect mix, but here I am.
Keith
It be interesting to see the dyno plots from your shocks. In watching the video it looks like the car is tracking well or you have a really good grip on the wheel. Did it track ok?
The early gtm's came with yellow konis and they can be used inverted for the coil springs to clear the control arm or in some cases the sway bars, the later gtm's have black konis and they can't be run inverted. Factory five has a retro fit to run the black shocks so they clear the upper control arm but it doesn't work very well.
Keith, Thanks for the info. I am using the corvette variable effort steering and active handling with the corvettes front and rear sway bars with 5.5 deg of caster but I haven't run the car over 80 mph
I was hoping the shock, spring, swaybar combo would do the trick as well. I also added the AGR 165 power rack and MR2 pump to the mix. This setup has a stiffer ride than the stock setup even though I have softer springs on all four corners. Also the tires will contact the swaybar before I reach full lock in both directions.
If I were to guess just based on observations of my car (keep in mind I have no background in racing or suspension setup) the stock setup is over sprung and under dampened. My current combination is probably over dampened and maybe over sprung still. I'm not crazy about being Goldilocks in search of the perfect mix, but here I am.
Keith
If the surface was perfectly smooth I would have no problems letting my hands off the steering wheel at triple digits. But as soon as one of the tires hits a expansion joint or some other minor imperfection and you see/feel the steering wheel rotate and then self correct, it just doesn't inspire confidence to push further.
I'm bummed that you have power steering and still have this challenge because that was another direction I was looking at to minimize the aggressive steering.
"But as soon as one of the tires hits a expansion joint or some other minor imperfection and you see/feel the steering wheel rotate and then self correct, it just doesn't inspire confidence to push further."
Adding the power steering did help that problem quite a bit. You don't get that sudden road induced jerk on the wheel. On the other hand the power rack has a quicker ratio witch is great for the twisty roads, but takes a bit of getting used to at speed.
Keith
"But as soon as one of the tires hits a expansion joint or some other minor imperfection and you see/feel the steering wheel rotate and then self correct, it just doesn't inspire confidence to push further."
Adding the power steering did help that problem quite a bit. You don't get that sudden road induced jerk on the wheel. On the other hand the power rack has a quicker ratio witch is great for the twisty roads, but takes a bit of getting used to at speed.
Keith
Thanks for the info. It sounds like something to add to the list of things I want.
Steve
I talked to Ted (LSman) of Quick Racing Products today. He is the supplier of my Genesis shock package and swaybar. He had seen the video and wanted to make sure I don't have a problem with one or more of the shocks. I don't even know how to rate that kind of service after a sale. Proactive Service and Support! Amazing! Thanks Ted & Ron! I doubt there is a problem but I'll update everyone once we check.
To add a little more data to the equation. Some of you have seen my project, not a GTM but very similar in stats and virtually exactly the same in suspension, weight bias total weight etc maybe slightly longer wheelbase.
I am running 7.5 deg caster, manual rack, qa1 double adjustables. Car is awesome at speed. Occasionally get a slight bump steer type thing but only on a severe pothole never over an even bump or drop. Raising the car slightly (3/8") helped the geometry and eliminated most of this may or may not help a GTM depending..... I have had the car over 175 so far, holding at that till I finish my splitter/wing aero stuff. Mojave mile in the spring to really push it!
eddie, looking forward to seeing that monster in action! i'm sure that 1/4 mile time was traction limted to say the least. i know you're not finished yet, how about some vids man?! i've been looking for a rat rod project, now i'm starting to question the rat part!
To add a little more data to the equation. Some of you have seen my project, not a GTM but very similar in stats and virtually exactly the same in suspension, weight bias total weight etc maybe slightly longer wheelbase.
I am running 7.5 deg caster, manual rack, qa1 double adjustables. Car is awesome at speed. Occasionally get a slight bump steer type thing but only on a severe pothole never over an even bump or drop. Raising the car slightly (3/8") helped the geometry and eliminated most of this may or may not help a GTM depending..... I have had the car over 175 so far, holding at that till I finish my splitter/wing aero stuff. Mojave mile in the spring to really push it!
The rack is stock c5 without any power run to it, not sure on the ratio. I was worried about it being to stiff, some would probably think so. I actually like it and did great with it autocrossing, no arm pump
Springs are 325 front 675 rear but these probably aren't very good comparison since my mounting/pickups and angles would are different from yours. I may be slightly more rear bias too after I thought about it. I'm right at 62/38 more rear than I was hoping for. I was afraid it was going to push really bad but was very happy with the way it ended up feeling.
Springs are 325 front 675 rear but these probably aren't very good comparison since my mounting/pickups and angles would are different from yours.
First,,, that is one bad a$$ hot rod you're building. I've been following your thread in the OT section and in reviewing the pictures the rear looks fairly close to a GTM setup although I can only see the tabs/mounting for the front but it looks close as well. Are you running C5 arms up front as well? Can you share any information about your QA1's?
First,,, that is one bad a$$ hot rod you're building. I've been following your thread in the OT section and in reviewing the pictures the rear looks fairly close to a GTM setup although I can only see the tabs/mounting for the front but it looks close as well. Are you running C5 arms up front as well? Can you share any information about your QA1's?
Thanks
c5 front and rear http://www.summitracing.com/parts/hal-dd401/overview/
I have bought a lot of qa1 product and have been really happy never a problem mostly hot rods though not really pushing the product except for a couple cars
c5 front and rear http://www.summitracing.com/parts/hal-dd401/overview/
I have bought a lot of qa1 product and have been really happy never a problem mostly hot rods though not really pushing the product except for a couple cars
Thanks. I took the liberty of contacting QA1 and they sent the graphs for the double adjustables. I've overlayed the numbers from the dynos I had done on the yellow and black Konis. The thich red line is the yellow Konis at the stiffest rebound setting, the thick green line are the blacks. Also,,, as the QA1's are 18x18 adjustable, so each line represents two clicks.
They said they can be run inverted.
Eddie,,, do you happen to know where you have yours set??
Now your asking a lot! hmmm I am guessing here as I started low and have worked my way up.
front around 3 compression and 1-2 rebound
Rear probably 7-8 compression and 3 rebound
I feel like I am a little under sprung on the rear and will probably go up another 50 lbs on the spring rate. I made my own mount on the A arm and am not as far out as the factory shock mount. I am losing more to leverage than I would like, but thats how it is. The heavier spring will do me some good.
Now your asking a lot! hmmm I am guessing here as I started low and have worked my way up.
front around 3 compression and 1-2 rebound
Rear probably 7-8 compression and 3 rebound
I feel like I am a little under sprung on the rear and will probably go up another 50 lbs on the spring rate. I made my own mount on the A arm and am not as far out as the factory shock mount. I am losing more to leverage than I would like, but thats how it is. The heavier spring will do me some good.
Thank you! I'm kinda liking these shocks. They have a really wide range of adjustablity. Looks like RCR ships them with their kits as well.
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but If you watch the video you'll see I backed off real early. Watch my head and the car in relation to the horizon. See how much I'm bouncing around. At first I couldn't figure out what was going on. Was it a high speed stability issue, alignment? So I took a run in my son's Mustang and figured it out. The runway has dips in it. You could hardly notice it in the Mustang but the GTM was bucking like a Bronco!
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