69 Charger on the autocross

[j-c-c-62]

I think some shared expectations here are unrealistic with heavy cars, 50+ sidewalls grippy tires and any pressure under 35Psi.
It's hard to have 70's looks and 2020 performance.

 

[Rusty knuckles]

I think some shared expectations here are unrealistic with heavy cars, 50+ sidewalls grippy tires and any pressure under 35Psi.
It's hard to have 70's looks and 2020 performance.

1000%

I'm trying to get the most i can out of a true to form muscle car. The whole idea is you don't need to spend $20k on a bunch of sales pitches from XYZ company selling the latest "geometry correcting" doo-dad and performance enhancement.

I keep saying, these cars don't handle bad as reputations suggest. They just feel different. My hellcat corners flatter and accelerates faster than my charger. But it understeers terribly and the stopwatch says at best it's equivalent to the charger.

 

[Kern Dog]

yeah, I'm running 275/60/15 Nitto 555R's on the rear of my car and 215/70/15 Mickey Thompson Sportsman S/T's on the front. I think I want to put same size tires on all 4 corners for better balance and have thought of using the Nitto 555R2's since I want to keep 15" tires.

The regular 555R have a softer sidewall even when aired up to 28psi and I can feel a little shift at the start of a hard turn before they settle.
I thought I had heard the 555R2's have a stiffer sidewall, is that correct? Do the 555R2's let you feel sidewall shift when turning or do they feel like a normal radial tire and what psi do you run them at?

I wish it was possible to have a sticky tire with sharp steering response that also holds grip in a turn that also comes in 15" diameter.

I think some shared expectations here are unrealistic with heavy cars, 50+ sidewalls grippy tires and any pressure under 35Psi.
It's hard to have 70's looks and 2020 performance.

Absolutely.
To get sharp steering response from a 15 inch tire, you'd need a 50 series or shorter.
Dwayne's car looks great:

But it will not steer as sharp as it would with a 17" wheel and a 40 series tire. Taller sidewalls simply have more mass to flex.
You choose to either have a traditional drag race look and what goes with it or change to a bigger wheel and shorter sidewall for faster response.
I understand why many guys stick with the 15" wheel....They are a natural look for the classic car. I'm not a fan of razor thin sidewalls either.

 

[SlinktRR]

Rusty how did your 2025 season go? I'm doing an autox event later this month with my 70RR, installing nitto555r2 on 15x8's at all four corners based on your experience and I really love these tires, huge upgrade from the usual classic Mopar tire compounds. Also added a deep transmission pan from cope and a new trans cooler to combat the extra heat.

Did your 727 fail from too much heat on the course or was it due for a rebuild?

I'm used to doing autocross with an "old" bmw e46 m3 stick car which is pretty reliable on a road course but I have some concerns with the 727. May need to add a temp gauge for it as well.

 

[68 Sport Satellite]

Rusty how did your 2025 season go? I'm doing an autox event later this month with my 70RR, installing nitto555r2 on 15x8's at all four corners based on your experience and I really love these tires, huge upgrade from the usual classic Mopar tire compounds. Also added a deep transmission pan from cope and a new trans cooler to combat the extra heat.

Did your 727 fail from too much heat on the course or was it due for a rebuild?

I'm used to doing autocross with an "old" bmw e46 m3 stick car which is pretty reliable on a road course but I have some concerns with the 727. May need to add a temp gauge for it as well.

I don't autocross my car all the time, but to share some additional feedback on frequent use of a 727 for this application - I recall reading an article about the Hotchkis RR driven by Dan Weisharr. He started out with the stock 727 and burned up 3 of them before finally converting the car to a manual transmission. Not saying it will happen to you, but it could. Depends how hard you drive it I guess.

 

[SlinktRR]

Thanks yes that's what I'm afraid of. I'm not going to push all that hard, I'm mostly interested to see how it performs without burning it up in one outing. Even if I'm one and done for autocross with this car I'm keeping the nittos. Great modern 15" tire that's light years ahead of anything I have run on the RR before. I have an a833 sitting on the shelf as well so maybe it's time.

 

[Kern Dog]

I don't autocross my car all the time, but to share some additional feedback on frequent use of a 727 for this application - I recall reading an article about the Hotchkis RR driven by Dan Weisharr. He started out with the stock 727 and burned up 3 of them before finally converting the car to a manual transmission. Not saying it will happen to you, but it could. Depends how hard you drive it I guess.

A buddy of mine races a couple of B body Mopars in the 24 hours of LEMONS events and told me yesterday that they go through a 727 every TWO races!
How is it that a drag racer can shock the heck out of theirs over and over and it holds together while an endurance race like LEMONS wears them out? Maybe they get hot in continuous use?

 

[Rusty knuckles]

Rusty how did your 2025 season go? I'm doing an autox event later this month with my 70RR, installing nitto555r2 on 15x8's at all four corners based on your experience and I really love these tires, huge upgrade from the usual classic Mopar tire compounds. Also added a deep transmission pan from cope and a new trans cooler to combat the extra heat.

Did your 727 fail from too much heat on the course or was it due for a rebuild?

I'm used to doing autocross with an "old" bmw e46 m3 stick car which is pretty reliable on a road course but I have some concerns with the 727. May need to add a temp gauge for it as well.

It's been going well. I actually raced again yesterday and last one is in October. No issues with the 727 at all but I do try to manage my heat between runs by shutting down and opening my hood in the staging lane. Then I just push it until I'm a few cars back. I'm due to tear it down. It has a skip between 2nd and 3rd but its had this for 25 years. It's not changed on me in I think 4 seasons of racing now.

I do need to add an adjustable brake bias block. I can't brake as hard as I like because it weight transfers so hard to the nose the rear locks up easily. Which has made some cool powerslides and one 360 smoke show lol. I get a ton of compliments in how I can throw my car around. I'm still a bottom 1/3 of the field for time but its competitive enough and still quicker than any modern challenger or charger including my hellcat.

Go have fun. Drive it hard. Hang on tight! @SlinktRR I'd love to see some pics with your big tires!

 

[Rusty knuckles]

I don't have good video from outside the car but here's a couple shorts about it.

 

[j-c-c-62]

It's been going well. I actually raced again yesterday and last one is in October. No issues with the 727 at all but I do try to manage my heat between runs by shutting down and opening my hood in the staging lane. Then I just push it until I'm a few cars back. I'm due to tear it down. It has a skip between 2nd and 3rd but its had this for 25 years. It's not changed on me in I think 4 seasons of racing now.

I do need to add an adjustable brake bias block. I can't brake as hard as I like because it weight transfers so hard to the nose the rear locks up easily. Which has made some cool powerslides and one 360 smoke show lol. I get a ton of compliments in how I can throw my car around. I'm still a bottom 1/3 of the field for time but its competitive enough and still quicker than any modern challenger or charger including my hellcat.

Go have fun. Drive it hard. Hang on tight!

So, upping the front the TB's a tad and adding a Wilwood? brake rear bias adjuster are pretty easy reversable upgrades to address rear tire early lock up, or just get a grippier front pad compound, right? Bypassing any engine radiator trans cooling and upgrading the trans cooling with its own fan might help, and very frequent trans fluid changes would be a path I would take to help an auto crossed beat on 727. Asking a lot when using 180F? water to cool your transmission.

 

[Rusty knuckles]

So, upping the front the TB's a tad and adding a Wilwood? brake rear bias adjuster are pretty easy reversable upgrades to address rear tire early lock up, or just get a grippier front pad compound, right? Bypassing any engine radiator trans cooling and upgrading the trans cooling with its own fan might help, and very frequent trans fluid changes would be a path I would take to help an auto crossed beat on 727. Asking a lot when using 180F? water to cool your transmission.

I've resisted doing the torsion bars but yeah I think I'm there if I want to go faster. Like you say, easy change and every component I've installed is bolt on. So if I decide I want to put it back to stock thats pretty easy.

The ole drum brakes are alright and I dont think different shoes would help because I'm modulating the brake to be more controlled in the slow down. It also doesn't help that the engine is doing some braking only on the rear as well when slowing down. Man you want to talk about how to make your car mad. Brake hard and then down shift from 2nd to 1st before a hard turn. If you can hang on to it you'll be the highlight of the day!

 

[j-c-c-62]

Sorry, I wrongly assumed you had front discs. Yes, you have your hands full with drums with a big car on AX. Changing to grippier shoes might not be an improvement as you seem to already know in this case.
Car does sound tough on the video BTW.

 

[Rusty knuckles]

Sorry, I wrongly assumed you had front discs. Yes, you have your hands full with drums with a big car on AX. Changing to grippier shoes might not be an improvement as you seem to already know in this case.
Car does sound tough on the video BTW.

I hate to make the comparison but its kinda like a Harley. Makes a lot of noise to look cool but doesn't really match its power. Ha!

 

[j-c-c-62]

Hey, lipstick and High heels aren't exactly a structural improvement either.

 

[RemCharger]

Que in Kern about the vertical video in
3

2

1

 

[Kern Dog]

Ha ha....
Are your eyes like this:

Or this?

 

[j-c-c-62]

Ha ha....
Are your eyes like this:

View attachment 1918148

Or this?

View attachment 1918149

That might be useful at the cinema or the opera on big hat nights.

 

[SlinktRR]

NT555r2's on magnum 500's. 275/60 R15. I've always been a raised white letter Mopar owner, but not after taking these out for a long drive. So much traction I'll never go back.

 

[68 Sport Satellite]

NT555r2's on magnum 500's. 275/60 R15. I've always been a raised white letter Mopar owner, but not after taking these out for a long drive. So much traction I'll never go back.

View attachment 1918401

View attachment 1918402

View attachment 1918403

what psi do you run on the street? I have the first version 555R's out back 275/60/15 and run them at 28 psi on the street, then at the 1/4 mile track once every few years at
12-18 psi. I've been thinking of trying the 555r2's for a bit stiffer sidewall.

 

[Rusty knuckles]

what psi do you run on the street? I have the first version 555R's out back 275/60/15 and run them at 28 psi on the street, then at the 1/4 mile track once every few years at
12-18 psi. I've been thinking of trying the 555r2's for a bit stiffer sidewall.

I actually dont adjust mine much. I run 45 front for autocross and 40 rear. For winter I'll take them down to 35 for just sitting. They're rated for 50 or 55 so I don't have any issue running them high.