crazycooter Posted August 13, 2008 Report Share Posted August 13, 2008 At between 140 and 160 mph I get a lot of rear end wobble. What axle do you folks recomend to fix this problem? Link to comment Share on other sites More sharing options...
ff500 Posted August 13, 2008 Report Share Posted August 13, 2008 Maybe slowing down a little bit Link to comment Share on other sites More sharing options...
CRQuarto Posted August 13, 2008 Report Share Posted August 13, 2008 Is this on a smooth, flat, level road? Don't be fooled by freeway pavement....even if at 80 miles an hour you don't feel it, the trucks and stuff that are stuck on during rush hour will impact the pavement causing ripples and such that will mess with you at those speeds. Your axle is doubtfully the culprit...I would start with your suspension. Link to comment Share on other sites More sharing options...
crazycooter Posted August 13, 2008 Author Report Share Posted August 13, 2008 Maybe slowing down a little bit Why slow down? Link to comment Share on other sites More sharing options...
crazycooter Posted August 13, 2008 Author Report Share Posted August 13, 2008 Is this on a smooth, flat, level road? Don't be fooled by freeway pavement....even if at 80 miles an hour you don't feel it, the trucks and stuff that are stuck on during rush hour will impact the pavement causing ripples and such that will mess with you at those speeds. Your axle is doubtfully the culprit...I would start with your suspension. It was on these farm to market roads around here. Whats a good suspension uprade? Link to comment Share on other sites More sharing options...
sharabi Posted August 13, 2008 Report Share Posted August 13, 2008 At between 140 and 160 mph I get a lot of rear end wobble. What axle do you folks recomend to fix this problem? So you had the governed speed limiter removed? Link to comment Share on other sites More sharing options...
ColdwaterHotrod Posted August 13, 2008 Report Share Posted August 13, 2008 At between 140 and 160 mph I get a lot of rear end wobble. What axle do you folks recomend to fix this problem? a Watts link will help at higher speeds Link to comment Share on other sites More sharing options...
DubbsFaris Posted August 13, 2008 Report Share Posted August 13, 2008 Once you get above 170 it goes away...you just have to ride it out... I find far more disturbing that at 175 all lights look blue and red to me!! Link to comment Share on other sites More sharing options...
crazycooter Posted August 13, 2008 Author Report Share Posted August 13, 2008 So you had the governed speed limiter removed? I said that between 140 and 160 never said above 160 I have not gone over 155 due to being unstable. What is the governed speed? Link to comment Share on other sites More sharing options...
ColdwaterHotrod Posted August 13, 2008 Report Share Posted August 13, 2008 around 155 Link to comment Share on other sites More sharing options...
frydguy79 Posted August 13, 2008 Report Share Posted August 13, 2008 i have noticed it as well when you are between 125-145 lots of side to side motion so how many have changed your speed limiter with a tune, and then where does it limit it too? Link to comment Share on other sites More sharing options...
Son of GT Posted August 13, 2008 Report Share Posted August 13, 2008 A serious answer? Install a larger (and I mean LARGER) rear spoiler on the back of the car. Link to comment Share on other sites More sharing options...
rpretzel Posted August 13, 2008 Report Share Posted August 13, 2008 Although this car will do 155 off the showroom floor, it wasn't built to do it. This is a street car. At those kinds of speeds, I'm sure you are running into all sorts of aerodynamic issues. This car is a brick, and it's pushing a lot of air. A different rear spoiler would probably help keep the rear planted a little better. You might want to look into the front aerodynamics as well. Suspension upgrades would probably help as well. Performance springs could help. Lowering the car a bit means less air underneath. All the stock bushings are extremely soft, so I would look into performance LCAs, UCA, sway bars. A watts link would certainly help the side-to-side motion. Performance shocks & struts would also firm up the suspension a bit. Even new tires should help. The stock F1s suck. If all that fails...slow down. Link to comment Share on other sites More sharing options...
Cobramach1 Posted August 14, 2008 Report Share Posted August 14, 2008 A serious answer? Install a larger (and I mean LARGER) rear spoiler on the back of the car. Son of GT is right! There's a reason the 2000 Cobra R had such a large rear spoiler and that specialized front chin. It wasn't for looks! Link to comment Share on other sites More sharing options...
crazycooter Posted August 14, 2008 Author Report Share Posted August 14, 2008 If this car was not meant to go that fast then why do I own it and why will it run that fast? Link to comment Share on other sites More sharing options...
ColdwaterHotrod Posted August 14, 2008 Report Share Posted August 14, 2008 why are all your questions about speed? are you planning to outrun the law or race a vette? Link to comment Share on other sites More sharing options...
markhudd Posted August 14, 2008 Report Share Posted August 14, 2008 I have the FRPP FR1SVT Power Upgrade (CAI, FRPP axle back exhaust), does anyone know if that would disable the governed speed limiter? Thanks. Mark Link to comment Share on other sites More sharing options...
mustang crazy Posted August 14, 2008 Report Share Posted August 14, 2008 I have the FRPP FR1SVT Power Upgrade (CAI, FRPP axle back exhaust), does anyone know if that would disable the governed speed limiter? Thanks. Mark Mind was stable at 160 limiter not removerd.I read on some fourm that someone removed and had gps @ 195 do know how true. Link to comment Share on other sites More sharing options...
crazycooter Posted August 14, 2008 Author Report Share Posted August 14, 2008 why are all your questions about speed? are you planning to outrun the law or race a vette? You never know what I might have to do! lol Na I just miss running 160+ like I used to do on my crotch rocket and when I run fast I like to have some demented idea of control. Link to comment Share on other sites More sharing options...
sprint200 Posted August 14, 2008 Report Share Posted August 14, 2008 I don't think a larger spoiler is the answer. In fact the OE piece works too well at those speeds, which is why the KR has the V6 spoiler. I think the second part of rpretzel's post is closer to the mark; all the soft bushings and "Sunday Driver" suspension parts that make this car a nice "Cruiser" are more likely the culprit. Although I wouldn't rule out the rear end being slightly off-center or mis-aligned. Another thing to check is whether one of the wheels is slightly out of balance and the harmonics are showing up at those speeds. I've had mine up near 150 for repeated laps at the Texas World Speedway this past March and it was rock solid. If it wasn't for the left turn at the end of the straightaway it would have been a "non-event". But there's not a piece of stock suspension left on my car........... Link to comment Share on other sites More sharing options...
KCMO-GT500 Posted August 14, 2008 Report Share Posted August 14, 2008 I have the FRPP FR1SVT Power Upgrade (CAI, FRPP axle back exhaust), does anyone know if that would disable the governed speed limiter? Thanks. Mark mark while I am not sure, I imagine that ford is not able to change that parameter for the same reason that it is there in the first place, safety and liability. that is also why the tune they provide is not as aggressive as some of the others John Link to comment Share on other sites More sharing options...
DubbsFaris Posted August 14, 2008 Report Share Posted August 14, 2008 If this car was not meant to go that fast then why do I own it and why will it run that fast? Cuz the dealership was fresh out of rockets? You own it cuz you are crazy coozer... It runs that fast because it can... Any other mysteries need solving, I'll be down at the pub... Link to comment Share on other sites More sharing options...
Son of GT Posted August 14, 2008 Report Share Posted August 14, 2008 I don't think a larger spoiler is the answer. In fact the OE piece works too well at those speeds, which is why the KR has the V6 spoiler. I think the second part of rpretzel's post is closer to the mark; all the soft bushings and "Sunday Driver" suspension parts that make this car a nice "Cruiser" are more likely the culprit. Although I wouldn't rule out the rear end being slightly off-center or mis-aligned. Another thing to check is whether one of the wheels is slightly out of balance and the harmonics are showing up at those speeds. I've had mine up near 150 for repeated laps at the Texas World Speedway this past March and it was rock solid. If it wasn't for the left turn at the end of the straightaway it would have been a "non-event". But there's not a piece of stock suspension left on my car........... Actually, it's the other way around. The FoMoCo engineers put the V6 spoiler on the KR because it provides 35% more downforce over the stock GT500 spoiler. I don't disagree that suspension upgrades are not a necessary part of the equasion, but rear aerodynamic downforce on speeds in excess of 130 MPH is a extremely critical component to keep the car stable. F1 and Indy car races have been lost because of damaged spoilers and other ground effects components because the car goes all over the track and the driver can't keep it under control. In crazy's situtation, the main culprit that is the cause of the rear end wobble is because the rear of the car begins to get light as a result of the airflow that accumlates under that area of the car. Having a "boy racer" or R2000 rear spolier would stabilize the rear end becuase of the tremendious amount of downforce being applied at 160 M.P.H. That's why Plymouth installed those giantic spoilers on the Superbirds, and that was one of the key features that allowed them to kick everyone's ass for two seasons before NASCAR said no more. Link to comment Share on other sites More sharing options...
markhudd Posted August 14, 2008 Report Share Posted August 14, 2008 mark while I am not sure, I imagine that ford is not able to change that parameter for the same reason that it is there in the first place, safety and liability. that is also why the tune they provide is not as aggressive as some of the others John John, Could I, or should I get a more aggressive tune with the existing mod? Thanks. Look forward to going for another ride someday soon. Mark Link to comment Share on other sites More sharing options...
mciarochi Posted August 14, 2008 Report Share Posted August 14, 2008 Had mine in that vicinity a couple of times on stock suspension. I noticed once that with a mild crosswind I was loose at 130, and backed off. That might have something to do with it. Other than that, tighten it up. LCA and Watts at a minimum, or LCA, UCA, springs and anti-sway upgrade. Link to comment Share on other sites More sharing options...
sprint200 Posted August 14, 2008 Report Share Posted August 14, 2008 Actually, it's the other way around. The FoMoCo engineers put the V6 spoiler on the KR because it provides 35% more downforce over the stock GT500 spoiler. I don't disagree that suspension upgrades are not a necessary part of the equasion, but rear aerodynamic downforce on speeds in excess of 130 MPH is a extremely critical component to keep the car stable. F1 and Indy car races have been lost because of damaged spoilers and other ground effects components because the car goes all over the track and the driver can't keep it under control. In crazy's situtation, the main culprit that is the cause of the rear end wobble is because the rear of the car begins to get light as a result of the airflow that accumlates under that area of the car. Having a "boy racer" or R2000 rear spolier would stabilize the rear end becuase of the tremendious amount of downforce being applied at 160 M.P.H. That's why Plymouth installed those giantic spoilers on the Superbirds, and that was one of the key features that allowed them to kick everyone's ass for two seasons before NASCAR said no more. Sorry, but your going to have to explain to me how a V6 spoiler that lays flat as a pancake creates more downforce than the GT500 spoiler sticking way up in the air. I guess that THIS article is just a bunch of hooey about reducing rear downforce and balancing the front and rear grip.... The R2000 type spoilers are very good for large amounts of downforce on road courses where you need traction coming out of moderately slow corners where the air is not moving that fast. The faster the straightaways, the less wing you want in order to maximize top end speed. However this reduces your cornering "grip".........so it's always a balancing act.....in a real race car. For a street car you pick a happy medium. The superbirds had quite a bit more air getting under the car than we do too..... mciarochi, You were probably loose exactly because there was too much rear downforce and with any extra wind the front end got light......... Link to comment Share on other sites More sharing options...
Boston Mike Posted August 15, 2008 Report Share Posted August 15, 2008 You never know what I might have to do! lolNa I just miss running 160+ like I used to do on my crotch rocket and when I run fast I like to have some demented idea of control. Dude, I'm in Texas and I have never ever seen an armadillo other than dead on the side of the road. Doing 140-160 of the FMs will do one of two things eventually.................give the armadillo a friend to lay with or "click-click". But good luck with all that. Link to comment Share on other sites More sharing options...
Son of GT Posted August 15, 2008 Report Share Posted August 15, 2008 Sorry, but your going to have to explain to me how a V6 spoiler that lays flat as a pancake creates more downforce than the GT500 spoiler sticking way up in the air. I guess that THIS article is just a bunch of hooey about reducing rear downforce and balancing the front and rear grip.... "The R2000 type spoilers are very good for large amounts of downforce on road courses where you need traction coming out of moderately slow corners where the air is not moving that fast. The faster the straightaways, the less wing you want in order to maximize top end speed. However this reduces your cornering "grip".........so it's always a balancing act.....in a real race car. For a street car you pick a happy medium." The superbirds had quite a bit more air getting under the car than we do too..... mciarochi, You were probably loose exactly because there was too much rear downforce and with any extra wind the front end got light......... It does because it hangs off the deck lid farther than the GT500 ducktail does. Even if the V6 spoiler only extends past the decklid 1" more than the Ducktail does, it will create more downforce on the rear of the car than the ducktail would. Although the ducktail does provide significant downforce at speeds up to 120 M.P.H., because it's more vertical than the V6 spoiler, at higher speeds the airflow over the ducktail starts to break up and move vertically as opposed to the V6 spoiler which causes the airflow to press down on the rear of the car due to it's over hang. My statement that the V6 spoiler provides 35% more downforce than the GT500's ducktail didn't come out of my rear end, it came directly from FoMoCo's press release of the KR. I was suprised and dismayed that FoMoCo decided to install the V6 spoiler on the KR, so I decided to reasearch why; and what I posted in the above paragraph is what I found out from that reasearch. And I don't disagree with the Edmunds article; I've read it before and it's not "hooey". A taller R2000 type spoiler would provide more downforce at slower speeds by virtue of it's size and vertical positioning on the decklid, but that in itself also causes more parasitic drag at higher speeds too. But its that drag that's keeping the rear of the car planted down. The're right; in a street car you would want to strike a balance between the two needs (good low speed downforce with only moderate drag at high speeds), and even though our ducktail spoilers meet that balance, they can't provide the necessary downforce needed at 150 M.P.H. or faster. If you have a chance, please take a look at a picture of a Bonneville salt flat race car. The spoilers on those cars are low but extend quite a few inches (a foot?) over the decklid of those cars because the're designed to keep the rear of the car planted down at speeds exceeding 150+ M.P.H. The "superbullet" style Bonneville cars have vertical stabilizers on them in order to keep them in s straight line at speeds of 300+ M.P.H., but the slower cars all have low, overhung spoilers mounted on them. Same thing with Prostock dragsters too. They usually have a large, but low slung spoiler on their decklids for the same reason that the Bonneville cars do. And if you have ever seen a rear engined rail type dragster get airborne midway down the strip, odds are that both the front and rear spoilers were not adjusted properly which caused the rail to have excessive downforce in the rear and not enough downforce in the front. Link to comment Share on other sites More sharing options...
sprint200 Posted August 15, 2008 Report Share Posted August 15, 2008 The press release that I read (here) states that... The GT500KR’s impeccable balance of handling and performance is the result of a holistic approach to the development, looking at the total vehicle with chassis and powertrain engineers working together to optimize all vehicle attributes. For example, a new front splitter and revised rear spoiler aid in aerodynamic improvements, adding downforce over the front axle and moving the center of aero pressure forward in the vehicle to improve high-speed balance and stable, predictable braking character. The ride height has been lowered to the optimum setting for on-the-limit handling, lowering the front by 20 mm and the rear by 15 mm. This is why I wrote what I did in my previous posts. Not trying to pick a fight or anything. It's just that this is the first time I've heard this claim and I've just never seen any published information stating your case? edit for color change to highlighted text. Link to comment Share on other sites More sharing options...
crazycooter Posted August 15, 2008 Author Report Share Posted August 15, 2008 Dude, I'm in Texas and I have never ever seen an armadillo other than dead on the side of the road. Doing 140-160 of the FMs will do one of two things eventually.................give the armadillo a friend to lay with or "click-click". But good luck with all that. You live in texas and have never seen a live armadillo man you need to get out a little more! nothing wrong with running those speeds Link to comment Share on other sites More sharing options...
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