You are comparing a mid engined car to your previous experiences with front engined cars. Two VERY different animals. Mid and rear engined cars are MUCH harder to control when the back end breaks loose. Basically, as I have said in the past, you don't want this to happen, and should do whatever you can to avoid the rear tires from breaking traction.
You have ridiculous amounts of HP in a relatively light car. If you don't want to spend the $$ on things that will keep your rear tires from losing traction, well, I don't know what else to say.
If I were you, I would get the alignment correct, for sure, but I would also look into some REAL aero devices that build downforce at higher speeds, traction control, and STICKY TIRES. If you neglect any one of these things, it is likely you will have a bad experience at a high rate of speed in a GTM...or any other car for that matter.
Again, as I have said many times, going 200 MPH, or even 150+ is a very dangerous proposition and should be addressed as such...in ANY car. If you do this, please make sure to also wear the proper safety equipment as well.
Not trying to preach, just want everyone to be safe in their GTMs.
Yes i understand that. If i was worried about it i wouldn't have put twin turbos in it. the rear is going to break loose, it's a matter of being able to control it. As it sits today it's dangerous. In my camaro and my vette i was able to control the rear spinning and not loose control. This cars steering scares me as it sits because the car will be going 160 + and at that speed the steering as it is now will cause an accident.
Two cents worth: X2 what has been said so far
Just something to think about.
When talking traction/steering control think in complete package including aero when reaching for sky high speed
Veyron, Ferrari, Zonda, Lamborghini, Koenigsegg, they all have great steering, aero, and huge amounts of power and they use traction control to help them to keep going in the correct direction
__________________ "May you be in heaven a full half hour before the Devil knows you're dead".
You are comparing a mid engined car to your previous experiences with front engined cars. Two VERY different animals. Mid and rear engined cars are MUCH harder to control when the back end breaks loose. Basically, as I have said in the past, you don't want this to happen, and should do whatever you can to avoid the rear tires from breaking traction.
You have ridiculous amounts of HP in a relatively light car. If you don't want to spend the $$ on things that will keep your rear tires from losing traction, well, I don't know what else to say.
If I were you, I would get the alignment correct, for sure, but I would also look into some REAL aero devices that build downforce at higher speeds, traction control, and STICKY TIRES. If you neglect any one of these things, it is likely you will have a bad experience at a high rate of speed in a GTM...or any other car for that matter.
Again, as I have said many times, going 200 MPH, or even 150+ is a very dangerous proposition and should be addressed as such...in ANY car. If you do this, please make sure to also wear the proper safety equipment as well.
Not trying to preach, just want everyone to be safe in their GTMs.
I never said i wasn't going to use sticky tires. I never said i wasnt going to add areo devices. All i have stated was i wasn't happy with the steering and i was curious what others have done. This is the first round of getting the car where it needs to be, other items are in the works, I'm just not at that point yet. if i don't like the car steering at 60-80 MPH, adding devices will not do much if anything for me at these speeds. i'm taking this one step at a time. I appreciate all the advice. Will i use all of it, who knows? If i can't get the car to act how i want it to act then more support/devices will get added. Please do not feel offended if i do not jump out and say "OMG that's exactly what i'm going to do, thank you". I do value your opinion so thank you.
Quote:
Originally Posted by Presto51
Two cents worth: X2 what has been said so far
Just something to think about.
When talking traction/steering control think in complete package including aero when reaching for sky high speed
Veyron, Ferrari, Zonda, Lamborghini, Koenigsegg, they all have great steering, aero, and huge amounts of power and they use traction control to help them to keep going in the correct direction
Yes i understand that. these cars are sold to upper class people and those people "typically" do not understand how to drive a car without it. Just like when people started disabling the tracton control on the ZR1's all of a sudden (when they first came out) these were top news stories. XXX person learned the hard way about leaving traction control on.... Bla bla bla.
Again i'm not worried about the rear breaking loose. it simply helped make my point on the streering. I don't like it and I, like others, what to know how to make it better. I'm soaking all this in and i'm looking at the options. I'll work the options one step at a time until i rectify the issue. Ultimatly the car will be running MT drag radials (345). I'm still unsure on the front tires but they will prob. be 275's. this will help with traction in the rear and steering in the front. Also i'll be putting a boost by speed device on the car. So the car will only put out what's reasonably safe to propell the car forward. A rear wing along with a front airdam are planned, just not purchased yet. This is only the second GTM that i know of (perhaps there are others) that is capable of 1000 + HP. There is going to be a huge learning curve on getting it right. So please don't get upset with me if i disagree or don't use your opinion. I have been around and driven high HP cars for over 10 years now. By no means do i know it all and i don't pretent to. I'll weight the options and execute from there. Thank you very much for the input. I'll start with getting more caster in the front tires and then work on new shoes. we will see what happens from there. You do make some great points though, thank you again!
__________________
GTM build in progress
first start with TT's Video
First drive with TT's :) Video
This does not apply to a normal daily driver unless you drive like crazy and or have high HP.
So at 80 mph you break traction in a straight line.
Does the car still track straight or does the rear of the GTM move to the left or right?
If the rear of the GTM is not staying straight, find out why.
Use a string or a laser across the rear wheel at center line towards the front of the GTM through center line of front wheels. Measure from center of front hub out to your string or laser. Do this on both sides. Are they exactly the same?
If the above measurement is exactly the same, you may have a rear toe link flex issue.
Too test your rear toe link, you sit on the floor and grab the rear wheel with your hands and move the wheel front and rear and look for toe change (put some muscle into it or use your legs). Yes this takes a little effort but think of the load is applied by the rear tires under acceleration and braking (more than you can muscle). The inner toe link frame mount flexes in and out. The small square tubing that the mount is mounted too spans a long distance. The tubing actually flexes (twists). So guess what happens when the rear toe changes. Uncontrolled rear steering.
Team PDG posted what was done to the Racing GTM about 4.5 years ago. Team PDG cross braced the toe link frame pickup points to the center of frame under the transmission.
First let me say I have never been a high HP car guy, never had the money for it. Rice rockets are so much cheaper!
Linxs,
I too am very concerned for the handling of the GTM at high speed as I love top speed runs, drag races, etc. Thinking about the rear breaking loose, from your videos it looks like your running the Ricardo. I am not sure as to how much % lock up it has. (as I said I am not a car guy, Bikes only have one drive wheel) I know there is many factors in why a car slides out when breaking loose. But I thought one of the main reason's was when one tires looses traction first even for a sec before the other breaks loose. The wheel that held the traction last tries to pass the car. Reason I brought that up is because Giken has a LSD that locks up 100% under a load keeping both drive wheels spinning at the same speed and in theory they will both have to break looks at the same time keeping the car straighter. ( My conclusion mind you, please feel free to correct me on this! ) I have been thinking of getting this LSD installed just for that reason. Don't get me wrong I don't care about the car breaking traction either I didn't go with turbos but I am not short on cubes! But I do want to be able to control it.
I really hope you can get this thing under control, I see the guy getting out of you car in the start up video with the 200mph Texas Mile shirt and I know they don't sell them with out the time slip! Anyway see you there!
This does not apply to a normal daily driver unless you drive like crazy and or have high HP.
So at 80 mph you break traction in a straight line.
Does the car still track straight or does the rear of the GTM move to the left or right?
If the rear of the GTM is not staying straight, find out why.
Use a string or a laser across the rear wheel at center line towards the front of the GTM through center line of front wheels. Measure from center of front hub out to your string or laser. Do this on both sides. Are they exactly the same?
If the above measurement is exactly the same, you may have a rear toe link flex issue.
Too test your rear toe link, you sit on the floor and grab the rear wheel with your hands and move the wheel front and rear and look for toe change (put some muscle into it or use your legs). Yes this takes a little effort but think of the load is applied by the rear tires under acceleration and braking (more than you can muscle). The inner toe link frame mount flexes in and out. The small square tubing that the mount is mounted too spans a long distance. The tubing actually flexes (twists). So guess what happens when the rear toe changes. Uncontrolled rear steering.
Team PDG posted what was done to the Racing GTM about 4.5 years ago. Team PDG cross braced the toe link frame pickup points to the center of frame under the transmission.
The car doesnt track straight. There is flex!! you are 100% correct, I'll have to put in some supports to remove that. We noticed this when it was on the alignment machine. I forgot about this. <added to list of things to do>
Quote:
Originally Posted by flotowngtm
First let me say I have never been a high HP car guy, never had the money for it. Rice rockets are so much cheaper!
Linxs,
I too am very concerned for the handling of the GTM at high speed as I love top speed runs, drag races, etc. Thinking about the rear breaking loose, from your videos it looks like your running the Ricardo. I am not sure as to how much % lock up it has. (as I said I am not a car guy, Bikes only have one drive wheel) I know there is many factors in why a car slides out when breaking loose. But I thought one of the main reason's was when one tires looses traction first even for a sec before the other breaks loose. The wheel that held the traction last tries to pass the car. Reason I brought that up is because Giken has a LSD that locks up 100% under a load keeping both drive wheels spinning at the same speed and in theory they will both have to break looks at the same time keeping the car straighter. ( My conclusion mind you, please feel free to correct me on this! ) I have been thinking of getting this LSD installed just for that reason. Don't get me wrong I don't care about the car breaking traction either I didn't go with turbos but I am not short on cubes! But I do want to be able to control it.
I really hope you can get this thing under control, I see the guy getting out of you car in the start up video with the 200mph Texas Mile shirt and I know they don't sell them with out the time slip! Anyway see you there!
The ricardo is the tranny that's in the ford GT's. A stock ricardo was in the GT in the florida mile that went 260+ (or it was 258 MPH i can't remember). I think the GT was reported putting out 1700 to the tire? It's a good point i will look at what the lock up is on the LSD. I always assumed it would be fine, but it doesn't hurt to check!
__________________
GTM build in progress
first start with TT's Video
First drive with TT's :) Video
No matter what you do, there will always be gyroscopic forces produced because of the spinning internals of the engine and transmission. Dirt bike guys use this phenomenon to their advantage all the time, so while what Don mentioned should definitely be looked into and WILL be an issue if you stress the GTM hard, just know that you will NEVER get rid of the gyro effect of the spinning engine. It WILL make the car want to turn sideways when the rear tires are no longer contacting the ground well.
There used to be a wrist/hand strengthening devise on the market that used a spinning ball inside it to do exactly what I am talking about. The spinning forces created a gyroscopic effect, and the user tried to resist this effect in order to strengthen their wrist and hand muscles. Don't know if these exist anymore though.
Well I'm gonna be stubborn here and disagree with any gym having suspension flexing problems that affect straight line acceleration. The engine mounts are simply to close to the rear axle line for the frame to actually make much flex .... it would half to just break in order to move any distance that's going to make a difference. Now if it was front engine .... sure that might be possible
No matter what you do, there will always be gyroscopic forces produced because of the spinning internals of the engine and transmission. Dirt bike guys use this phenomenon to their advantage all the time, so while what Don mentioned should definitely be looked into and WILL be an issue if you stress the GTM hard, just know that you will NEVER get rid of the gyro effect of the spinning engine. It WILL make the car want to turn sideways when the rear tires are no longer contacting the ground well.
There used to be a wrist/hand strengthening devise on the market that used a spinning ball inside it to do exactly what I am talking about. The spinning forces created a gyroscopic effect, and the user tried to resist this effect in order to strengthen their wrist and hand muscles. Don't know if these exist anymore though.
Well I'm gonna be stubborn here and disagree with any gym having suspension flexing problems that affect straight line acceleration. The engine mounts are simply to close to the rear axle line for the frame to actually make much flex .... it would half to just break in order to move any distance that's going to make a difference. Now if it was front engine .... sure that might be possible
Take a look at the rear toe bar it flexes under heavy load. Where it's moutnied to the frame. I agree with you on the motor, especially if you use solid mounts.
__________________
GTM build in progress
first start with TT's Video
First drive with TT's :) Video
Well I'm gonna be stubborn here and disagree with any gym having suspension flexing problems that affect straight line acceleration. The engine mounts are simply to close to the rear axle line for the frame to actually make much flex .... it would half to just break in order to move any distance that's going to make a difference. Now if it was front engine .... sure that might be possible
If there is one thing about the PDG team that has been consistent the entire time I have been working with them, it is that they do not address an issue until it actually IS an issue. The rear toe link flexing thing was a pretty early on fix for problems with inconsistent rear toe measurements. These things DO flex quite a bit, and when 1/16 of an inch of toe at the wheel makes a huge difference in the handling of the car, it can easily get, and exceed, this amount through toe link mount flexure. Definitely not an area you want to disregard if you are stressing the rear at all. Don is right on the money, IMHO.
I have been around drag racing long enough to know it takes tons of torque to flex a frame. Even though my car has savage acceleration once the pro charger spools, off the line it's an underpowered low compression small block with an extra drag on the belts.
Two motors are gonna flex a frame .... A really high compression motor on race fuel ... Or a roots/screw blower motor ... With tons of torque right out of the hole. If you tried that in a gtm you would shatter any transaxle I dont care what it's rated for.
Now I'm not saying cornering won't flex it . I'm only talking about engine produced frame flex from acceleration straight line drag racing leading to traction loss and the rear wanting to come around is most likely which ever side the car is heavier on or which ever side the tire slips on first ... Certainly not frome frame twist.
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