Wheelbase
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If it's going to be like a Promod car (& if the rules haven't changed for 2006), Promod's wheel base max for a door car is 115", full size trucks is 140", & small trucks is 125".
If all you run is mostly 1/8 mile, staying at 112" might be an idea (112" sounds a lot better than the factory 108"). If you plan on running mostly 1/4 mile, 114-115" might be better. The longer wheelbase car will weigh a little more, but it might also have more re-sale value at 114-115". I don't remember how long the magazines said Mike Ashley's PM Stang was but it might be something to check into.
Are you planning to stagger (offset) the wheelbase side-to-side at the front, or mount the struts even (square)?
**EDIT** The type of motor should also be taken into account when deciding on wheelbase. If the car is going to be about as fast as a Super Comp class car (8.90's) the 115" max will most likely be excessive. On the other hand a blown PM motor good for 6.30's - 6.50's could be a scary handfull at only 108" wheelbase.
If all you run is mostly 1/8 mile, staying at 112" might be an idea (112" sounds a lot better than the factory 108"). If you plan on running mostly 1/4 mile, 114-115" might be better. The longer wheelbase car will weigh a little more, but it might also have more re-sale value at 114-115". I don't remember how long the magazines said Mike Ashley's PM Stang was but it might be something to check into.
Are you planning to stagger (offset) the wheelbase side-to-side at the front, or mount the struts even (square)?
**EDIT** The type of motor should also be taken into account when deciding on wheelbase. If the car is going to be about as fast as a Super Comp class car (8.90's) the 115" max will most likely be excessive. On the other hand a blown PM motor good for 6.30's - 6.50's could be a scary handfull at only 108" wheelbase.
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Wheelbase stagger
A chebby friend that has bought more than a few used kinda fast chassis cars (4.90's to 4.70's) over the years & has rotated the same few motors into most all these same cars. What he found was that for his driving style he liked the cars with staggered wheelbase better when running a pro tree.
The staggered wheelbase presented a slightly larger shadow in the staging beams (with shallow staging) giving him a little more room to squeeze the tree a little harder without redlighting.
When his current car was built it had about 1/2" stagger, after re-doing the front clip I bumped it to around 5/8" stagger. I think the max is around 1" stagger for door cars.
A chebby friend that has bought more than a few used kinda fast chassis cars (4.90's to 4.70's) over the years & has rotated the same few motors into most all these same cars. What he found was that for his driving style he liked the cars with staggered wheelbase better when running a pro tree.
The staggered wheelbase presented a slightly larger shadow in the staging beams (with shallow staging) giving him a little more room to squeeze the tree a little harder without redlighting.
When his current car was built it had about 1/2" stagger, after re-doing the front clip I bumped it to around 5/8" stagger. I think the max is around 1" stagger for door cars.
G
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·Wheel Base
Why do you want to lengthen it from 112"? Are you trying to get more engine set back? Look at Pro stockers. They have 105" wheelbase. I guess it's just personall preference. My car is 108" & handles fine. Jim Geese (Vanishing Point Race Cars) asked if I wanted to build it on a longer wheelbase. He said it would allow him more options on engine placement but that the 108" wheelbase would handle fine also. The 108" was already stretching the 98 Stang wheelbase 7" from stock. If I had gone any longer it would start to look like a funny car. What is stock WB on a 69? I know my 67 Stang was 108". I would stay with the 112". I think that will do whatever you want. Just my 2 cents. Good luck.
Why do you want to lengthen it from 112"? Are you trying to get more engine set back? Look at Pro stockers. They have 105" wheelbase. I guess it's just personall preference. My car is 108" & handles fine. Jim Geese (Vanishing Point Race Cars) asked if I wanted to build it on a longer wheelbase. He said it would allow him more options on engine placement but that the 108" wheelbase would handle fine also. The 108" was already stretching the 98 Stang wheelbase 7" from stock. If I had gone any longer it would start to look like a funny car. What is stock WB on a 69? I know my 67 Stang was 108". I would stay with the 112". I think that will do whatever you want. Just my 2 cents. Good luck.
385"............. make it match the series of engine!
I think the 112 is enough, unless it was blown, then I'd look to increase it.
How did the car handle before it was wrecked. That'd be your best indication of whether to do it or not. Can you get ahold of the prior owner?
I think the 112 is enough, unless it was blown, then I'd look to increase it.
How did the car handle before it was wrecked. That'd be your best indication of whether to do it or not. Can you get ahold of the prior owner?
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I ran 1" offset with a 108" whellbase in 1978 with the pro tree. According to NHRA rules at that time, you were allowed a maximum variance of 1" from side to side so I went ahead and placed it all in the front suspension. It only allowed an additional 1" of rollout, however every little bit helped. In the late 80's when we started running Pro Mod the car was a handfull, more than likely as the result of the shorter 108" wheelbase and an outdated chassis. The only advantage to staggering the front suspension is if your going to work the lights with shallow staging for quicker ET's and deep staging to trim a little off the ET.
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Being a chassis builder I can tell you that if you're building a tube chassis car and going with a strut set-up, putting in stager is not only a great benefit (IMHO) but is as easy as doing one side then moving the jig up and doing the other. It increases your roll out and actually gives you a running (re moving) start at the light. IMHO, if you DON'T do it, you'll be behind the power curve to those who have it. If you do do it, use all the rule book allows you to have.
Rob
Rob
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Since this thread was first started, a few things have changed regarding the "need" for wb stagger on some P/M (and T/S) cars. This is mostly due to the spragless converters with the new ultra-high HP big/tall fin stator design ($$$) finding increased favor in more & more of some P/M cars lately (vs a clutch). And also delay boxes being allowed in some of the P/M classes (like the ADRL) to work with the converter/trans brake setup.
With a delay box/converter/brake setup, there is no need for any wb stagger for adjusting/effecting a P/M's red lights since the delay box now does that job. Having said that, wb stagger can (as before) still be a useful tool on non-delay box P/M & T/S cars to help reduce/control possible redlights.
With a delay box/converter/brake setup, there is no need for any wb stagger for adjusting/effecting a P/M's red lights since the delay box now does that job. Having said that, wb stagger can (as before) still be a useful tool on non-delay box P/M & T/S cars to help reduce/control possible redlights.
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Mmmmm, sounds like a whole lot of electronics going on. I always thought Pro Mod cars used clutches with Lenco's or Liberty's. And I always thought stagger was used to cheat the other guy out of winning. I guess I've been out of it too long.
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The recent move to the converter driven setups (like the Lencodrive & Bruno/Lenco) over the time tested clutch/Lenco setup in P/M probably never would have happened without the recent mentioned stator design advances allowing the converters to consistantly handle the 2500+ HP numbers. But the birth of the ADRL circuit also played a big part because of their "outllaw/anything goes" way of thinking when it comes to the P/M rules. They split the blown & nitrous cars into two different classes so there was no more juggling the rules to pacify the crying about fairness/leveling the playing field you see with the NHRA/IHRA P/M cars. And their "no minimum weight-no maximum cubic inch" thinking on rules meant that the P/M guys could once again experiment & try new (and old) ideas again instead of just building the same old "cookie-cutter" cars to fit the more restrittive NHRA/IHRA rules.
Without their hands tied on weight & cubic inch numbers, there was once again experimentaion with engine height/fore-aft placement, trans setups, and electronics. At first most didnt mind admitting to using a delay box.......but the use of the real-time traction control boxes (like the Davis unit) was kept a secret by a lot of teams at first, even though the rules permited them. But now that everyone is pretty much used to the idea of a computer controlled traction device, they don't mind admitting to using them in classes that allow them like the ADRL/outlaw P/M & 10.5" tire cars.
At a recent local TOPMA P/M show in Kennedale TX there was a converter in probably 85% of the Pro Mod cars. One of the remaining clutch holdouts at that show was a blown sbc vette. They said they had tried the Lencodrive earlier, but it didn't work for them (at this time) and switched back to a clutch for now.
And because of the no minimum weight rule, a lot of the P/M guys were putting the cars drastic diets. Some guys have tried rear frame sections made out of Titanium instead of 'moly, Titanium firewalls instead of steel, standard rear end setups instead of full floater rears (that has changed though), CarbonFiber wheelie bars, new ultra-light weight CarbonFiber bodies insted of the normal Carbonfiber bodies, etc, etc, etc.
Heads-up drag racing will always evolve....if the rules let it.
Without their hands tied on weight & cubic inch numbers, there was once again experimentaion with engine height/fore-aft placement, trans setups, and electronics. At first most didnt mind admitting to using a delay box.......but the use of the real-time traction control boxes (like the Davis unit) was kept a secret by a lot of teams at first, even though the rules permited them. But now that everyone is pretty much used to the idea of a computer controlled traction device, they don't mind admitting to using them in classes that allow them like the ADRL/outlaw P/M & 10.5" tire cars.
At a recent local TOPMA P/M show in Kennedale TX there was a converter in probably 85% of the Pro Mod cars. One of the remaining clutch holdouts at that show was a blown sbc vette. They said they had tried the Lencodrive earlier, but it didn't work for them (at this time) and switched back to a clutch for now.
And because of the no minimum weight rule, a lot of the P/M guys were putting the cars drastic diets. Some guys have tried rear frame sections made out of Titanium instead of 'moly, Titanium firewalls instead of steel, standard rear end setups instead of full floater rears (that has changed though), CarbonFiber wheelie bars, new ultra-light weight CarbonFiber bodies insted of the normal Carbonfiber bodies, etc, etc, etc.
Heads-up drag racing will always evolve....if the rules let it.
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What's the ADRL? In fact, what's the AHRA or the IHRA out on the west coast? Is the "index" for Top Sportsman still 7.90? Perhaps your best betThe recent move to the converter driven setups (like the Lencodrive & Bruno/Lenco) over the time tested clutch/Lenco setup in P/M probably never would have happened without the recent mentioned stator design advances allowing the converters to consistantly handle the 2500+ HP numbers. But the birth of the ADRL circuit also played a big part because of their "outllaw/anything goes" way of thinking when it comes to the P/M rules. They split the blown & nitrous cars into two different classes so there was no more juggling the rules to pacify the crying about fairness/leveling the playing field you see with the NHRA/IHRA P/M cars. And their "no minimum weight-no maximum cubic inch" thinking on rules meant that the P/M guys could once again experiment & try new (and old) ideas again instead of just building the same old "cookie-cutter" cars to fit the more restrittive NHRA/IHRA rules.
Without their hands tied on weight & cubic inch numbers, there was once again experimentaion with engine height/fore-aft placement, trans setups, and electronics. At first most didnt mind admitting to using a delay box.......but the use of the real-time traction control boxes (like the Davis unit) was kept a secret by a lot of teams at first, even though the rules permited them. But now that everyone is pretty much used to the idea of a computer controlled traction device, they don't mind admitting to using them in classes that allow them like the ADRL/outlaw P/M & 10.5" tire cars.
At a recent local TOPMA P/M show in Kennedale TX there was a converter in probably 85% of the Pro Mod cars. One of the remaining clutch holdouts at that show was a blown sbc vette. They said they had tried the Lencodrive earlier, but it didn't work for them (at this time) and switched back to a clutch for now.
And because of the no minimum weight rule, a lot of the P/M guys were putting the cars drastic diets. Some guys have tried rear frame sections made out of Titanium instead of 'moly, Titanium firewalls instead of steel, standard rear end setups instead of full floater rears (that has changed though), CarbonFiber wheelie bars, new ultra-light weight CarbonFiber bodies insted of the normal Carbonfiber bodies, etc, etc, etc.
Heads-up drag racing will always evolve....if the rules let it.
would be with the Texas Lotto.
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The current AHRA is supposed to be the old, long dead AHRA sanctioning body from many-many years ago, brought back to life.
The ADRL has been around for a few years. Their growing popularity is mostly due to the much looser "no rules" (other than safety rules of course) format.
http://www.adrl.us/index.php/main/insidepage/rules/
From what I have read what is considered the "generic" Top Sportsman class index number does change depending on the sanctioning body/racing circuit/or area of the country. I know here in north Texas The Outlaw T/S cars use a 4.70 - 1/8 mile index. This year they did vote to lower the index to 4.50, but early on not enough cars could run the number so the index was bumped back to 4.70.
The ADRL has been around for a few years. Their growing popularity is mostly due to the much looser "no rules" (other than safety rules of course) format.
http://www.adrl.us/index.php/main/insidepage/rules/
From what I have read what is considered the "generic" Top Sportsman class index number does change depending on the sanctioning body/racing circuit/or area of the country. I know here in north Texas The Outlaw T/S cars use a 4.70 - 1/8 mile index. This year they did vote to lower the index to 4.50, but early on not enough cars could run the number so the index was bumped back to 4.70.
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I believe Dave and I have gotten off the original subject of wheelbase here. As we have all witnessed the Top Fuel cars have grown in wheelbase as they have gotten much quicker over the years. The thought process is while the shorter wheelbase will react and transfer weight quicker on the launch it will also react to changes in track conditions much quicker during the run. This can represent a certain level of instability as the driver is required to react quicker and the possibilty of over reaction is present. The front end offset was originally introduced by a fella by the name of "BIG DADDY" Don Garlits for those of you who have been around awhile. Garlits was an innovator and revolutionised much of what we see today. So, think ahead and if you're planning on going real fast, check on your respective sactioning bodies rule and lengthen that wheelbase as much as the rules will permit. Be sure to slow the steering ratio in order to avoid over reacting on your way down the track.
As far as the stagger goes, it depends on your perspective on things and what type of racing your focused on. If it's bracket racing you need to focus on the timing equipment and tricking the lights as much as possible. It's 90%at the starting line. Heck, I remember building an oil pan that would pick up the starting line beams after the trailing edge of the front tires ended. Talk about running much faster than your time slip.... "It's only cheating if you get caught." Be sure to put allot of thought into everything you do and look for opportunities that might give you an advantage over the next guy. Don't be afraid to try something nobody else has. Be innovative and use your immagination. Dave, I still think the converter cars and black boxes have taken all the fun out of drag racing......
As far as the stagger goes, it depends on your perspective on things and what type of racing your focused on. If it's bracket racing you need to focus on the timing equipment and tricking the lights as much as possible. It's 90%at the starting line. Heck, I remember building an oil pan that would pick up the starting line beams after the trailing edge of the front tires ended. Talk about running much faster than your time slip.... "It's only cheating if you get caught." Be sure to put allot of thought into everything you do and look for opportunities that might give you an advantage over the next guy. Don't be afraid to try something nobody else has. Be innovative and use your immagination. Dave, I still think the converter cars and black boxes have taken all the fun out of drag racing......
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When Jerry first started this thread his Mustang project was a more conventional full chassis layout that was getting a new front half. But now that the project has been upgraded to a completely new chassis/fiberglass body with a tri-pod mounted strut setup (vs the older design with the strut top mounted to the down bars from the firewall) and more modern "double adjustable" 4-link chassis brackets (for a much larger 4-link adjustment window to play with) it will be interesting to see how wheelbase plays into the mix.
Check out his pic link in the first post, you get an interesting comparison between his old, newer, & brand new setups. It's going to be damn cool.
Check out his pic link in the first post, you get an interesting comparison between his old, newer, & brand new setups. It's going to be damn cool.
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