Dirt Late Models Compared To Modifieds

[LewTheShoe]

I'm interested to understand more about similarities and differences between dirt late models and modifieds, other than the obvious bodywork distinctions. I'm thinking upper level racing series... say Lucas Oil or WOO late models as compared to DIRTcar big block modifieds or something similar. At the upper levels, I think the engines are pretty similar...?

One question I'm really curious about... If you follow the evolution of dirt modifieds and late models back to the post WWII era, do you find that they both directly descended from the same thing... street cars that typically had fenders/running boards removed, until Detroit design/styling advanced to integrated fenders post WWII? Any thoughts on this theory of dirt track evolution?

I recall the summer of 1971, when I worked a summer internship in Harrisburg, Pa. Sprint cars were king, but the modified racing scene was very vibrant and was the headline series at some tracks. I recall a popular bumper sticker: "RACING IS -- Modifieds On A Dirt Half Mile"

 

[gnomesayin]

Interesing topic, and it will be cool to read responses from those who know more. To me, it seems there some different turning points in the evolution of dirt modifieds and late models.

I believe that technically the use of "modified" as a class predates late models, and descends as you state from the first race cars that were significantly modified from street models post-WWII. Late models came along slightly later in the '60s and '70s, when the need to distinguish between older stock chassis and the newer, faster, and lighter models that were becoming popular. The late model division quickly became a top showcase class (except for areas where sprint cars ruled) with more lenient rules and faster evolution.

In all but a few states -- NY, PA, northern OH, and right across the border from there in Canada -- modifieds since the late '70s and early '80s have meant IMCA style modifieds and offshoots of that, such as USRA / USMTS and UMP. There are obvious major differences between Northeastern modifieds and modifieds everywhere else. The driver sits in the center of a NE big block or 358 modified, the chassis are somewhat taller and narrower, and the suspensions are more complex. It seems to me that the NE modifieds share more conceptually with the super modified classes that were popular in the '60s and '70s, and the IMCA descended modifieds everywhere else held on to the illusion of having a stock / street car counterpart for much longer. Both variants weigh in the 2500-2600 lbs range.

One important distinction is that the IMCA sanctioned modified class was created to be a mid-level class, between the top classes (late models and sprint cars) and street / hobby stocks. They were designed to use a stock '68-'72 Chevelle front clip, run on relatively small tires, and most famously featured an engine claim rule to keep expensive high HP motors out. Over time these modifieds have become a top class in many areas, with suspension rules opened up, quick change rear ends, bigger motors, etc. But some of their characteristics still show those early budget class roots.

Late models have never been anything but a top level class, and they quickly got very expensive as technology advanced. For a time they were close to an unlimited class, and they've had to be reined in several times since (see the outlandish wedge cars from the '80s with angled bodies and huge sail panels).

Today's late models have shorter wheel bases and somewhat more regulated bodies than what I grew up watching in the '80s and '90s, but they've still managed to end up a beast unlike any other. To anyone who ever mentions "twisted sister" cars, I tell them to take a look at a dirt late model and the crooked noses, left side being 10" taller than the right side, etc. They look kinda silly, but they can put on some great racing. They're faster than any type of modified because of bigger tires, lower center of gravity, lighter weight (2300-2400 lbs) and more powerful engines (mostly because they can get more power to the ground because of those other advantages).

 

[Yogisd1]

Here in California sprint cars, and super modifieds raced together at most tracks. The difference between them and modifieds, were modifieds had carbs instead of fuel injection. The only difference between late models, and modifieds was late models were full bodies, and modifieds were open wheel cars. That was back in the 70's and early 80's. I'm not sure if carbs are used in either class anymore. They probably run modern fuel injection like NASCAR does, but I can't be sure. I'm not as involved as I used to be.

 

[gnomesayin]

No, late models and modifieds are still running four barrel carburetors. Some of the lower versions of these classes like limited late models and the ever more popular due to affordability B-mods are using two barrel carbs to keep HP down.

 

[LewTheShoe]

I believe that technically the use of "modified" as a class predates late models, and descends as you state from the first race cars that were significantly modified from street models post-WWII. Late models came along slightly later in the '60s and '70s, when the need to distinguish between older stock chassis and the newer, faster, and lighter models that were becoming popular. The late model division quickly became a top showcase class (except for areas where sprint cars ruled) with more lenient rules and faster evolution.

In all but a few states -- NY, PA, northern OH, and right across the border from there in Canada -- modifieds since the late '70s and early '80s have meant IMCA style modifieds and offshoots of that, such as USRA / USMTS and UMP. There are obvious major differences between Northeastern modifieds and modifieds everywhere else. The driver sits in the center of a NE big block or 358 modified, the chassis are somewhat taller and narrower, and the suspensions are more complex. It seems to me that the NE modifieds share more conceptually with the super modified classes that were popular in the '60s and '70s, and the IMCA descended modifieds everywhere else held on to the illusion of having a stock / street car counterpart for much longer. Both variants weigh in the 2500-2600 lbs range.

One important distinction is that the IMCA sanctioned modified class was created to be a mid-level class, between the top classes (late models and sprint cars) and street / hobby stocks. They were designed to use a stock '68-'72 Chevelle front clip, run on relatively small tires, and most famously featured an engine claim rule to keep expensive high HP motors out. Over time these modifieds have become a top class in many areas, with suspension rules opened up, quick change rear ends, bigger motors, etc. But some of their characteristics still show those early budget class roots.

Late models have never been anything but a top level class, and they quickly got very expensive as technology advanced. For a time they were close to an unlimited class, and they've had to be reined in several times since (see the outlandish wedge cars from the '80s with angled bodies and huge sail panels).

Today's late models have shorter wheel bases and somewhat more regulated bodies than what I grew up watching in the '80s and '90s, but they've still managed to end up a beast unlike any other. To anyone who ever mentions "twisted sister" cars, I tell them to take a look at a dirt late model and the crooked noses, left side being 10" taller than the right side, etc. They look kinda silly, but they can put on some great racing. They're faster than any type of modified because of bigger tires, lower center of gravity, lighter weight (2300-2400 lbs) and more powerful engines (mostly because they can get more power to the ground because of those other advantages).

Lots of good perspective in this post, so thank you for taking the time and effort to post it. Yeah, I am aware that IMCA mods (and similar variants) are a budget-minded, mid-level class that has become very widespread. I guess that today, when most people refer to dirt modifieds, they generally are talking about IMCA-style modified racing.

My interest in this thread is to understand more about the Northeast big block mods, how these NE cars compare to top-level late models, and also to learn if top-level mods continue to thrive elsewhere besides the Northeast... or indeed if they are even thriving in the PA/New England area.

When I lived in PA, I don't believe there was any late model racing, and still isn't much today as far as I know. There are a handful of shows by Lucas Oil or WOO late models, but I don't think late models are important in weekly racing shows. Back in the day, modifieds were not part of the undercard... they were the featured class. Mods and sprint cars didn't share a program either on the same night. I don't know about today. Certainly my attention has been more on sprint cars, not modifieds, not late models, in recent years.

I was surprised by your comments that late models would be "faster than any type of modified" and have more tire than the Northeast mods. So I looked up qualifying times from the Charlotte World Finals last November. Yep, the WOO modifieds ran ~15.6 seconds fast time, while the late models were a full second quicker.

 

[LewTheShoe]

Here in California sprint cars, and super modifieds raced together at most tracks. The difference between them and modifieds, were modifieds had carbs instead of fuel injection.

I guess semantics can be confusing. When I hear "super modifieds," I think of paved tracks and offset engines either with or without wings... very low and very fast. Is that what you are referring to?

 

[gnomesayin]

One thing I've been surprised by is that the current IMCA style modifieds, especially of the UMP (now running under the DirtCar banner I believe) and USMTS sanctions that have less restrictive rules, are quite a bit faster than some realize. They certainly don't compare to late models or sprints, but I recall Bob Dillner posting that UMP mods were running lap times not far off the big block guys at Volusia a year or two ago.

 

[gnomesayin]

Weight matters a lot in dirt racing, and I'm not sure why the big block modifieds are designed to weigh approximately 200 more lbs than late models, and where that weight is concentrated.

 

[Yogisd1]

I guess semantics can be confusing. When I hear "super modifieds," I think of paved tracks and offset engines either with or without wings... very low and very fast. Is that what you are referring to?

No. Both sprints and super mods were built with the engine in the center of the frame, directly in front of the driver. This is a pic of them on asphalt. They would turn around and race the same cars
the next night on dirt tracks. This was around 1972.

 

[gone]

Modifieds technically predate Dirt Late Models, mainly due to how the evolution occurred.

The first cars raced could be called modifieds, since they were stock cars that had been modified (bodywork removed to save weight, some engine modifications). Many were built from the ground up for racing - bankrolled by car manufacturers. When racing got more widespread, in the quest for more speed it was easier to modify a street car than to build a whole race car from scratch... the street car modifiers tended to stay at the grassroots level, while the guys who built cars from the ground up went on to Indianapolis.

Like usual, modifying street cars got expensive, so local tracks started classes that limited how much modifications you were allowed - the "street stock" classes. How much a modified or street stock evolved from there depended a lot on the local economy.

In the Northeast the economy tended to be pretty good, so more people spent more money. Dirt racers noticed that narrow chassis with a lot of controlled body roll went faster... pavement racers learned that wider chassis with less body roll was faster on their tracks. Since you're mainly interested in dirt racing, I'll leave this except to point out that's why ground-up built dirt modifieds and sprint cars are so much taller and narrower than their pavement counterparts.

In the midwest, where the economy wasn't as hot, IMCA brought back the modified race car based upon a street chassis, along with engine and tire limits.

Dirt Late Models came about when tracks thought that NASCAR's idea that race cars should look like street cars caused them to create new classes where what started as street stocks were allowed to spend more money modifying them... but they had to keep the original factory wheelbase and at least the outer shell of the bodywork (fenders and all). So although dirt late models have morphed into cars built from the ground up with few factory parts, they've tended to stick with the stock wheelbases. The body shells have evolved way past their street counterparts... in the 1980s and 1990s they got pretty radical (remember the wedge cars and the billboard cars?) so many tracks throttled them back, but still without headlight decals and brand stickers you wouldn't know which street cars they're supposed to represent.

By the way, NASCAR itself started with modified cars. But the southern economy was slow so these cars stayed truer to the street versions longer. NASCAR started out promoting modifieds as a higher class than their more street-like class, but the local economy caused the street-like class to grow much more rapidly and even today modifieds only are found in small pockets in the south while fuller body race cars are almost everywhere.

That's a probably over-simplified summary of how dirt late models became so different than today's modifieds... if you get to take a good squint at dirt late models across the country, as well as modifieds across the country, you'll find definite differences - some that make the cars unequal if they tried to compete directly with their same-named friends.

 

[gnomesayin]

In the Northeast the economy tended to be pretty good, so more people spent more money. Dirt racers noticed that narrow chassis with a lot of controlled body roll went faster... pavement racers learned that wider chassis with less body roll was faster on their tracks. Since you're mainly interested in dirt racing, I'll leave this except to point out that's why ground-up built dirt modifieds and sprint cars are so much taller and narrower than their pavement counterparts.

This is an interesting detail I hadn't thought about.

 

[gone]

No. Both sprints and super mods were built with the engine in the center of the frame, directly in front of the driver. This is a pic of them on asphalt. They would turn around and race the same cars
the next night on dirt tracks. This was around 1972.

View attachment 39723

True, but again what is called a "Supermodified" depends upon where you were in the country...

By the 1990s, Supermodifieds similar to what you pictured were changing - built with their engines offset to the left and even laid over almost on their sides - for better handling and aerodynamics, particularly on paved tracks. And you had a few mavericks like Bill Hite who built 4-wheel drive Supers... although he lived and built race cars in Alabama he raced those Supers in upstate New York.

Supers in California and the Pacific Northwest tended to remain "straight" (engine and driver in the center of the frame, instead of offset) longer than the Northeastern Supers. But in the 1990s they tried some heads-up west coast vs. east coast Super racing, and it didn't take the west coast guys long to see what the east coast guys were doing...

 

[gnomesayin]

Here are a couple examples of the excess of the wedge cars from the '80s and 90s.

1982:

1994:

 

[Yogisd1]

I've seen some of the newer supermods here in California. They have changed a lot since I was involved. There aren't very many of them out here. There is only one track I know of that races them, and I think it's only once, or twice a month. The fields aren't very big either. A twelve car field is about as big as I've seen. In a couple of more years there may be none left.

 

[LewTheShoe]

NASCAR started out promoting modifieds as a higher class than their more street-like class...

Thanks for your extensive post, a ton of good insight there. This is a fascinating factoid, IMO. I'd never realized that. I always assumed NASCAR's modified championship started a year earlier just as a stop-gap series until the strictly stock division could be launched. Wow, thanks.

In the Northeast the economy tended to be pretty good, so more people spent more money. Dirt racers noticed that narrow chassis with a lot of controlled body roll went faster... pavement racers learned that wider chassis with less body roll was faster on their tracks. Since you're mainly interested in dirt racing, I'll leave this except to point out that's why ground-up built dirt modifieds and sprint cars are so much taller and narrower than their pavement counterparts.

Why is a narrow track with more body roll faster on dirt? Seems counter intuitive to me. Is it because the car is steered with the throttle, tail out and rear tires spinning? I would still think a wider stance with low center of gravity would have more forward bite...?

 

[gnomesayin]

Why is a narrow track with more body roll faster on dirt?

I don't think it actually is, which is one of several reasons why in modern times, late models have a clear advantage over NE modifieds with a lower center of gravity allowing more efficient weight distribution, among other things. Dirt setups, chassis and suspension design have become a lot more complex and technical in the past couple decades. I think historically the thought was that more body roll and weight transfer allowed the right rear tire to 'set' into the surface (at least while it has moisture) and then gain forward bite to accelerate back off the corner. You've probably heard the notion that dirt track cars tend to be driven off the right rear, and pavement cars off the right front. I think this is less true today, or at least it's not that simple, as the way dirt cars are set up to drive a dry slick track doesn't differ as much from pavement setup theory.

 

[gone]

Why is a narrow track with more body roll faster on dirt? Seems counter intuitive to me. Is it because the car is steered with the throttle, tail out and rear tires spinning? I would still think a wider stance with low center of gravity would have more forward bite...?

It has to do with how you generate grip with your tires against the track surface.

On dirt, the surface gives way and the tires dig in. You actually use the corners of the tires (where the tread meets the sidewall) and get some of the sidewall dirty too - in the turns. On the straights you want to be straight up (tread contact only), but when you get into the turns you want those tire corners to dig in there - body roll is the symptom of weight transfer that helps you do that. A narrower, higher car produces body roll more easily.

On pavement the surface doesn't give way, so you can't dig the tire corners into the surface. You want to limit body roll to keep as much of your tread in contact with the pavement as possible - if you roll over onto your sidewall it doesn't provide as much grip as tread does, and it also wears quicker. So the pavement guys also work harder to avoid unloading their left side tires, in order to get better grip overall from all four tires.

As gnomesayin says, this is complicated and I may be over-simplifying... especially on the dirt side since some dirt surfaces get pretty hard or car classes with limited horsepower don't dig into the surface as much, so they are run more like pavement cars. But since we started talking with modifieds and late models I was more focused upon cars that have enough horsepower to spin their tires. Cars that steer with the throttle (mostly Sprint cars) are using a lot of weight transfer to hang their tails out. Late Models generate so much weight transfer that they can lift their left front tire, and you can see a wide open space between their bodywork and their left rear tire (compared to when they're on the straights or sitting still). But again, as gnomesayin points out, lately the late models have been controlling this action more, and trying to keep more loading on their left tires.

 

[KTMLew01]

http://hogantechnologies.com/dirt-late-model-chassis-tuning/

http://hogantechnologies.com/more-on-dirt-late-model-chassis-tuning/

https://www.hyperracing.com/pages/tech_department/chassis_setup/rethink_dirtadvanced_theory.aspx

 

[KTMLew01]

http://www.teamgrt.com/setup2.html

 

[KTMLew01]

https://www.hotrod.com/articles/ctrp-0612-rear-steer-technology/