A Question For Pro Mod Guys.

[W-409]

I have been planning to start a new ProMod build, and then I need to do a conversion from Factory Stock car body to ProMod body. So my question is, that do you usually narrow the body when building a Pro Mod, and if you do, how much?

What other things I should know or what other "Typical Mistakes" there are?

[stump]

Hi Niko,

Mate, while I do not consider myself an expert in such things, ProMods are indeed my favourite drag car.

I guess the main thing is wheel base. I believe most fall into the 110 - 115 inch wheel base. So you may need to stretch the body. Not saying ALL use this rule, but most would be a guess.

Having only built 2 ProMod bodies, the first one I stretched, but did not narrow, the second one (Camaro) was stretched and narrowed at the front. I also slightly widened the rear.

The second car was also 1:12, but from memory, I think I narrowed by approximately 6 scale inches. The cut tapered towards the rear, including the roof section.

The lower edge also benefited from a wedge piece glued along the entire length, helped to raise the rear for tyre clearance. Keep the front low, the rear higher.

Hope this helps your needs Niko.

[brett]

Really depends on what car it is Niko, first you may need to stretch the body usually behind the front wheels in front of the doors, some may also need a small stretch in front of the front wheels. Once you have that looking right you on average need to take about 8-10mm out of the front of the car (4-5mm either side of center ) and none from the back. find the center of the rear and run tape over to the front. Then you'll need to wedge the sides, cut and file both pieces together so they're exactly the same. Some cars you can add this wedge at the bottom of the sills( rocker panels), others you may need to install it in the sides again it depends on the car. Tape or glue the hood on before you cut anything, gluing will help hold things together a bit better while you're cutting.

Hope this helps a bit, I'm away for the next 3 days, so will check in then.

[W-409]

Thanks for the great tips and info Greg and Brett!

The car I will be building is 1960 Chevy Impala that has 119" Wheel base, so I guess I don't need to stretch that. For the Rocker panels, I will keep them original. That is the only thing I'm not so crazy about in some Pro Mods. Sometimes it looks really good, but in some bodies I think it don't and this is one of those. So I don't have to worry about that, though I'm going to get it as low as possible. Wow, how much you guys narrow those things was a surprise for me, I never thought that they actually were so narrow. Thanks, this is just the reason why I asked.

I've always liked ProMods too, they are my favorite Drag Cars, as Stockers & Super Stockers too. I'm not a Top Fuel Dragster type of guy, even if they are really fun to see on Drag Strips too.

This Gasser class '60 Impala inspired me to do this.

[ScaleDale]

The NHRA has to approve the body design of a Pro Mod before it's built. Some are narrowed and some are not. All are chopped and channeled to some degree. I like to stick to real world examples as best I can with drag models, so I went and joined the NHRA just to get access to the rule book. Here is the Pro Mod section and an approved blueprint of a Pro Mod Camaro built by Five star Race Car Bodies. Pick a body you want to build your P/M from and compare the body measurments to the ones allowed with the Camaro and you will get an idea as to what you can do if you stick to the rules. That's how I did my Pro Stock Mustang.

NHRA ProMod_Rules-2013.pdf

dims_ProModCamaro.pdf

Dale

[ScaleDale]

For a quick reference on narrowing, the overall width of a stock 2012 Camaro is 75.5 inches at the B post (behind the front door). The approved Pro Mod version of this body is 69 inches wide at this point, so it's been narrowed 3.5 inches. The stock wheelbase is 112 inches and the NHRA limit is 115, so it's been stretched by 3 inches.

On the '60 Impala, the 119 inch wheelbase is too long and it would need to be shortened by 4 inches. The width is 80 inches and the height is 54. You could narrow it 11 inches and chop it to 44 inches (10 inches). That's why the older body Pro Mods look like they have been chopped and channeled so much. They were so big to start with.

Dale

[1320wayne]

All of the info. given here is all good but the bottom line is whatever changes you make to the body that makes you happy.

This is simply my opinion but I don't ever get worked up too much with actual 1:1 measurements as a guideline. A lot of eyeball engineering and trial and error to get the desired results.

Here are a few shots of bodies that I have created and you should be able to see where most of the cuts and added styrene has been added. It will give you a basic idea of how much work may be involved in achieving what you are looking for.

Now, even though I don't think that actual measurements are all that critical reference material is invaluable. Most of what I created came by way of using every bit of real car ref. material as possible. For example, in the case of the 69 Daytona I used every bit of research available from Vanishing Point race cars website when it was up and running. That was over 100 detailed photos of how the real car was done.

I hope this helps in some way.

[ScaleDale]

Pretty much what Wayne said is better advise than mine. Pro Mod is the creative outlet of drag racing. Research, get a vision and create it. That's where the real fun is.

Dale

[comp1839]

niko, how will you be building this "pro mod" ? is it going to challenge your skills to build an accurate replica or are you going to build something "close" and put a pro mod sticker on it?

while neither direction is right or wrong (for you the builder). however, the advice you get, will be right or wrong based on the direction you choose.

[ScaleDale]

**EDIT**

What other things I should know or what other "Typical Mistakes" there are?

The biggest mistake any builder makes is not starting a project in the first place. Remember that it's not an $80,000 USD race car and the NHRA tech crew isn't going to inspect it. It's a plastic model. If you don't like the outcome, just start over. I have more junkers than I will admit to.

Now start building!

Dale

[comp1839]

niko, i will give you some things that are EXTREMELY important. the numbers i'm giving you are 1:1 numbers. this is so anyone can use these numbers in any scale IF THEY WISH TO.

we've all seen cars that are narrowed way too much. so much that the rear w/ wheels and tires on it won't fit inside the quarter panels. ovbiously "too" narrow. the rear width of the body can be determined by the width of the 4 link system you choose and the width of the tires plus clearance. on most pro mods and please note i said MOST pro mods ( i'm sure there are some out there that may be different) the four link system is between 16 and 20 inches on center (you can go to wark williams or strange engineering websites for their availlable widths). to get to the outside dimension of the 4 link add 1.5" you'll need 2" clearance on each inside of the tire. the cross section of each tire is around 22" ( you can go to goodyear or hoosier or m/t website for their info.). then add 2" per side for body clearance. so here's the tally.

16.0" center 4 link

1.5" to get to the outside dimension of the four link

4.0" inside to frame rail clearance ( l&r sides added together/ 2.0"per side)

44.0" cross section width of both rear tires (22" per tire)

4.0"body clearance (l&r sides added together / 2.0" per side)

----------------

69.5 total body width needed for this combo.

you can see the pro mod camaro body dale posted has a 70.125" width between the rear quarters over the tires.

if you want to build your body using 1:1 info. as a base for the body. i can go on.

I FIND the biggest mistake a builder can make, when starting a build like this, is not getting all of your thoughts together, not getting accurrate info. and not developing a plan on how to execute the build.

jumping in with both feet and no game plan is a sure recipe to building a "junker" as dale calls them.

[ScaleDale]

My process with builds like this is to collect as much reference stuff on-line as possible and study the heck out of it. I take 1:1 profile photos and scale them to match their 1:25 wheelbases and compare the measurements to the decal placement pages in the assembly instructions. I mark all the differences on the stock kit and look for surprises like different shaped wheel wells or variances between the distances in the length of quarter panels. Then I start to get a better picture of what I'm getting into. I studied the 2010 Mustang for weeks and still wrecked a body by not noticing that the hood wasn't cut in the center, but on each side.

The Camaro I was thinking about is so whacked out that I'm going to Pro Mod a '49 Merc just to relax and have a little more freedom to play.

Dale

[ScaleDale]

Another thought on the process here is that you need to finish all the body work before starting the chassis. Since the chassis must fit the body and the body is highly modded, all the pre visualization and measuring in the world will go out the window once the razor saw comes out. The finished product will be just different enough to mess us any finished chassis.

ChassisWorks.com sells kits for ProMod racers (1:1, sorry) and they note that the chassis should be assembled inside the body to assure a good fit.

Dale

[comp1839]

wow,....... good stuff, dale.

[DrKerry]

I'd like to build a Pro Mod, my biggest thing is I'm not wanting to do all the chassis work involved. I've seen chassis work that guys have done on here and think way kool!! But not something I want to tackle. So, maybe someday I'll wrap my mind around one and do it.....

[ScaleDale]

I'd like to build a Pro Mod, my biggest thing is I'm not wanting to do all the chassis work involved. I've seen chassis work that guys have done on here and think way kool!! But not something I want to tackle. So, maybe someday I'll wrap my mind around one and do it.....

There are some decent kit chassis in the Revell Pro Sportsman series cars. The 55 and 57 Chevy and the newer Jukebox Ford. Try adapting a body of your choice to one of these kits as a starter. Scratch building a chassis is a big undertaking regardless of skill level. The Model King re-issues of Pro Stock racers have good chassis, too. Your Mothers Old and the Match Race Firebird.

Dale

[W-409]

I haven't been much online for last couple of days. I was driving my Stock Eliminator Drag Race License with our '74 Chevelle at Finnish Championship Drag Race Event at Kalajoki Airport. I got the license and made one qualification run. Today I ran my best, 12,53 in K/SA but broke out even though I hammered the break pedal at the finishing line.

I just came home after 8 hours of sitting in a car, I'm feelin' a bit tired so I will read all of these posts again tomorrow and I'll send another reply then. Now it's bed time.

Edited July 21, 2013 by W-409

[brett]

good one Niko! nothing wrong for going to fast, next time you can lower your dial in time. Anyways back to your questions, some really good advice from everyone. Now I checked out the fit of the pro sportsman chassis on a Revell 60 and there's going to be a fair bit of modifying to get it to fit, so personally I think you're better off scratch building it . Now I'm no expert but I think if you follow my camaro build

http://www.modelcarsmag.com/forums/index.php?showtopic=74760&page=1

anyone can build a reasonable representation of what these cars should look like. By all means use styrene, talking to a modeller friend while I was away and taking a couple points from Dale's mustang build I may go back to styrene cages soon as well. Its not hard, break each section of cage down ie main rails, floor support, main hoops, drivers cage, back end etc. Each section isnt so hard broken down, it only as a whole that it looks confusing.

tried the pro stock pontiac chassis as well, way to narrow and too short a wheelbase, also harder to modify imo

[brett]

The Camaro I was thinking about is so whacked out that I'm going to Pro Mod a '49 Merc just to relax and have a little more freedom to play.

Dale

the pro sportsman chassis does fit pretty good under a merc though

http://www.modelcarsmag.com/forums/index.php?showtopic=44526&hl=%2B49+%2Bmerc#entry472850

[W-409]

First I want to say a big Thank You for all who has helped in this. When I started this topic, I couldn't imagine that I would get this much excellent information. Thanks!

The NHRA has to approve the body design of a Pro Mod before it's built. Some are narrowed and some are not. All are chopped and channeled to some degree. I like to stick to real world examples as best I can with drag models, so I went and joined the NHRA just to get access to the rule book. Here is the Pro Mod section and an approved blueprint of a Pro Mod Camaro built by Five star Race Car Bodies. Pick a body you want to build your P/M from and compare the body measurments to the ones allowed with the Camaro and you will get an idea as to what you can do if you stick to the rules. That's how I did my Pro Stock Mustang.

NHRA ProMod_Rules-2013.pdf

dims_ProModCamaro.pdf

Dale

For a quick reference on narrowing, the overall width of a stock 2012 Camaro is 75.5 inches at the B post (behind the front door). The approved Pro Mod version of this body is 69 inches wide at this point, so it's been narrowed 3.5 inches. The stock wheelbase is 112 inches and the NHRA limit is 115, so it's been stretched by 3 inches.

On the '60 Impala, the 119 inch wheelbase is too long and it would need to be shortened by 4 inches. The width is 80 inches and the height is 54. You could narrow it 11 inches and chop it to 44 inches (10 inches). That's why the older body Pro Mods look like they have been chopped and channeled so much. They were so big to start with.

Dale

Thanks for the Rulebook pages, and that ProMod Camaro blueprint. They'll help a lot. Actually I have 2012 NHRA Rulebook, but I will be building it with these 2013 rules, in case that there are some differences.

So a little shortening needs to be done. Luckily that shouldn't be a problem. You are right that those older ProMod bodies look much more chopped & channeled than newer ones. But they still are the coolest in my opinion, though it doesn't matter what body it has, a Pro Mod car is always very interesting. Thanks for the measurements too, I will use them on my build, since it's easier to build when there is an exact info of how these things should be done.

[W-409]

All of the info. given here is all good but the bottom line is whatever changes you make to the body that makes you happy.

This is simply my opinion but I don't ever get worked up too much with actual 1:1 measurements as a guideline. A lot of eyeball engineering and trial and error to get the desired results.

Here are a few shots of bodies that I have created and you should be able to see where most of the cuts and added styrene has been added. It will give you a basic idea of how much work may be involved in achieving what you are looking for.

-----

Now, even though I don't think that actual measurements are all that critical reference material is invaluable. Most of what I created came by way of using every bit of real car ref. material as possible. For example, in the case of the 69 Daytona I used every bit of research available from Vanishing Point race cars website when it was up and running. That was over 100 detailed photos of how the real car was done.

I hope this helps in some way.

That is another good way to do it. Those 1:1 measurements are not a must have for an experienced modeler that has done these things before too, but they help a lot when doing these first time I guess. I planned, that I will be doing so that I start cutting and building it to match those 1:1 measurements and then see how it looks. Then there is the possibility to do some modifications, if the result is not desired.

Thanks for the pics, they help a lot. It's great to see where you guys usually cut the body and other stuff like that. I will be using those for reference for sure.

I wish there would be more pics of '60 Impala Pro Modified but I guess that it's not the most common body. Though seeing other Pro Mod bodies and comparing them to original ones helps also, since it is possible to see where it has been stretched/shortened, cut etc.

Pretty much what Wayne said is better advise than mine. Pro Mod is the creative outlet of drag racing. Research, get a vision and create it. That's where the real fun is.

Dale

Well I wouldn't say that. Both of you had excellent advise and both replies were really helpful. I think that with combining the 1:1 measurements and looking at the result, maybe doing some modifications to get it look better without looking at the rulebook, will lead me to the best results.

.

[W-409]

niko, i will give you some things that are EXTREMELY important. the numbers i'm giving you are 1:1 numbers. this is so anyone can use these numbers in any scale IF THEY WISH TO.

we've all seen cars that are narrowed way too much. so much that the rear w/ wheels and tires on it won't fit inside the quarter panels. ovbiously "too" narrow. the rear width of the body can be determined by the width of the 4 link system you choose and the width of the tires plus clearance. on most pro mods and please note i said MOST pro mods ( i'm sure there are some out there that may be different) the four link system is between 16 and 20 inches on center (you can go to wark williams or strange engineering websites for their availlable widths). to get to the outside dimension of the 4 link add 1.5" you'll need 2" clearance on each inside of the tire. the cross section of each tire is around 22" ( you can go to goodyear or hoosier or m/t website for their info.). then add 2" per side for body clearance. so here's the tally.

16.0" center 4 link

1.5" to get to the outside dimension of the four link

4.0" inside to frame rail clearance ( l&r sides added together/ 2.0"per side)

44.0" cross section width of both rear tires (22" per tire)

4.0"body clearance (l&r sides added together / 2.0" per side)

----------------

69.5 total body width needed for this combo.

you can see the pro mod camaro body dale posted has a 70.125" width between the rear quarters over the tires.

if you want to build your body using 1:1 info. as a base for the body. i can go on.

I FIND the biggest mistake a builder can make, when starting a build like this, is not getting all of your thoughts together, not getting accurrate info. and not developing a plan on how to execute the build.

jumping in with both feet and no game plan is a sure recipe to building a "junker" as dale calls them.

Thanks for the great info! I need to take some good measurements on that Impala body so I can see how much I can narrow and where. Two last sentences are 100% true, I've been planning this build for one year now and I think I have some kind of a Game Plan. But of course, when the build starts, then I know if it works or not. But I guess it will work.

My process with builds like this is to collect as much reference stuff on-line as possible and study the heck out of it. I take 1:1 profile photos and scale them to match their 1:25 wheelbases and compare the measurements to the decal placement pages in the assembly instructions. I mark all the differences on the stock kit and look for surprises like different shaped wheel wells or variances between the distances in the length of quarter panels. Then I start to get a better picture of what I'm getting into. I studied the 2010 Mustang for weeks and still wrecked a body by not noticing that the hood wasn't cut in the center, but on each side.

The Camaro I was thinking about is so whacked out that I'm going to Pro Mod a '49 Merc just to relax and have a little more freedom to play.

Dale

I think this is exactly what I will do in here. The Mustang you are building is turning out very nice, and if I could get something even close as that, I would be very happy.

[W-409]

good one Niko! nothing wrong for going to fast, next time you can lower your dial in time. Anyways back to your questions, some really good advice from everyone. Now I checked out the fit of the pro sportsman chassis on a Revell 60 and there's going to be a fair bit of modifying to get it to fit, so personally I think you're better off scratch building it . Now I'm no expert but I think if you follow my camaro build

http://www.modelcarsmag.com/forums/index.php?showtopic=74760&page=1

anyone can build a reasonable representation of what these cars should look like. By all means use styrene, talking to a modeller friend while I was away and taking a couple points from Dale's mustang build I may go back to styrene cages soon as well. Its not hard, break each section of cage down ie main rails, floor support, main hoops, drivers cage, back end etc. Each section isnt so hard broken down, it only as a whole that it looks confusing.

tried the pro stock pontiac chassis as well, way to narrow and too short a wheelbase, also harder to modify imo

Yeah I am really happy with the record I ran even though I had little traction problems whole weekend. That was the only run where I didn't spin the tires much at the start. Though I did pretty massive burnout too. Only thing that still bothers me is that I didn't go full throttle to the end and make a massive break out, but a new record time. Well next time then.

I test fitted that Pro Sportsman chassis also when I first got the idea and you are correct, it will be easier to scratchbuild my own chassis. Actually your Camaro build with some others (Like Dale's Mustang for example) are bookmarked because of the great chassis and other work done. They are great reference material for this build. Only thing that I'm not sure is that should I try making that frame & cage from brass or styrene tubing... I've tried both, and both have their own challenges...

[ScaleDale]

Here are full specs on the 1960 Impala.

http://www.oldride.com/library/1960_chevrolet_impala.html

Dale

[W-409]

Yeah, actually I found that already, and then there is one 1:1 in the garage too, so I can check out some specs there as well.

Edited July 23, 2013 by W-409