GForce Engineering fully-fabricated 9” IRS With modified cradle

[Jon-MooredPerformanceLLC]

@Marc W didn’t you do testing with the 9in and lose 50 hp?

 

[Ta2ude]

@Marc W didn’t you do testing with the 9in and lose 50 hp?

I have read there is a 10-20 whp loss on a 800 hp car with the 9”.

 

[Marc W]

@Marc W didn’t you do testing with the 9in and lose 50 hp?

We did not come up with an exact number but you can read up on why the 9” exacts a hp price in drivetrain power loss. Has to do with pinion placement in relation to the ring gear. I basically went to the TH400 at the same time as the 9” rear. At that time a 3.40 ratio was the best you could do and that is too low to work with the 8spd if you were making 1000+ hp. I believe you can get 3.25 and 3.00 ratios with the 9.5” gears. Not sure. I haven’t shopped that for a while now. Back when I was doing that, it was really about trying not to break. The stuff available today wasn’t even dreamed of back then.

 

[Ta2ude]

So the farther I go down this rabbit hole the more complex it gets, leaving me with more questions than answers.
1) There seems to be a lot of discrepancy in regards to red eye driveshaft, axel and differential failures depending on where you look, some say problems and some say no issue. It’s hard to know what to believe, but wheel hop induced by pilot error may be the biggest culprit?
2) reducing wheel hop may be achieved through various BMR or AAD products
3) A modified cradle 9” rear end and 1 piece aluminum drive shaft with stronger 35 spline axels should address some potential failures but may slow down a stock red eye if traction gains aren’t substantial
3) Do you add more power via a PCM and tune before addressing suspension or after
4) When someone says they aren’t interested in doing power modifications you know it’s just a matter of time before the disease infects them

On a side note I am in Canada and the 9”IRS kit with driveshaft would cost me about $20,000 + Canadian with taxes duties and fees and I can get it with an extra set of axels for $5,000.
For me to buy the AAD performance Drag Pack I am at $3,530 plus whatever duties and brokerage fees they charge me.
The BMR cradle lockout kit would be about $430
A one piece aluminum driveshaft about $2000
Performance developments diff brace $1000

So do you go with the 9” IRS and modified cradle and plan on doing a stage 1 or stage 2 upgrade next year, believing that will be the extent of your performance modifications, or skip the “deal” and put the $5,000 elsewhere?

 

[Linda's Hell Cat]

So the farther I go down this rabbit hole the more complex it gets, leaving me with more questions than answers.
1) There seems to be a lot of discrepancy in regards to red eye driveshaft, axel and differential failures depending on where you look, some say problems and some say no issue. It’s hard to know what to believe, but wheel hop induced by pilot error may be the biggest culprit?
2) reducing wheel hop may be achieved through various BMR or AAD products
3) A modified cradle 9” rear end and 1 piece aluminum drive shaft with stronger 35 spline axels should address some potential failures but may slow down a stock red eye if traction gains aren’t substantial
3) Do you add more power via a PCM and tune before addressing suspension or after
4) When someone says they aren’t interested in doing power modifications you know it’s just a matter of time before the disease infects them

On a side note I am in Canada and the 9”IRS kit with driveshaft would cost me about $20,000 + Canadian with taxes duties and fees and I can get it with an extra set of axels for $5,000.
For me to buy the AAD performance Drag Pack I am at $3,530 plus whatever duties and brokerage fees they charge me.
The BMR cradle lockout kit would be about $430
A one piece aluminum driveshaft about $2000
Performance developments diff brace $1000

So do you go with the 9” IRS and modified cradle and plan on doing a stage 1 or stage 2 upgrade next year, believing that will be the extent of your performance modifications, or skip the “deal” and put the $5,000 elsewhere?

The real question is: do you want a street-friendly monster in the 750–850 HP range with mid-10s ET, or are you aiming for a track-focused beast pushing 1,000+ HP and dipping into the 9s?

 

[Ta2ude]

The real question is: do you want a street-friendly monster in the 750–850 HP range with mid-10s ET, or are you aiming for a track-focused beast pushing 1,000+ HP and dipping into the 9s?

At the moment I am interested in keeping it street friendly, as my wife and I enjoy driving it whenever possible in our Canadian climate but most of our drives are less than 60 miles on paved back roads. Going into the 9’s changes your requirements at the track up here so 10.001 would be the goal post for me currently.

 

[Linda's Hell Cat]

1) There seems to be a lot of discrepancy in regards to red eye driveshaft, axel and differential failures depending on where you look, some say problems and some say no issue. It’s hard to know what to believe, but wheel hop induced by pilot error may be the biggest culprit?
I think for what you want ET and HP wise, I'd keep your Redeye Driveshaft and axels.
2) reducing wheel hop may be achieved through various BMR or AAD products.
BMR is a very well known parts company and their parts were installed on my Husbands "Top Cat" Challenger. We were the original R&D and T&T for High Horse Performance with Joshua Schwartz. My husband loved R&D and wanted competitive parts. He didn't get to (rip) see as his Challenger 1st Manual into the 8's, his goal. But I watched the more HP his HC obtained, BMR wasn't holding up. I met Parker Bender owner of AAD at a race series I attend MSHS https://hemirace.com/. He gave me all the information about his products. Competitively, they are better and stronger. I pushed Josh to have them installed for T&T/ R&D and they held up to the higher HP, much better. I have the AAD parts installed on my HC Charger. I would spend your money on AAD.

3) A modified cradle 9” rear end and 1 piece aluminum drive shaft with stronger 35 spline axels should address some potential failures but may slow down a stock red eye if traction gains aren’t substantial
Not needed for the ET or HP you want.

4) When someone says they aren’t interested in doing power modifications you know it’s just a matter of time before the disease infects them
True, but do you want a Race car or a car you can race and Daily drive.
There are plenty of us who enjoy running 10’s—it’s more fun and far less stressful. The faster you go, the more maintenance and complexity you take on. At the last race, I met a forum friend who was new to racing. He had a Twin Turbo Built and Tuned Hellcat, spent a fortune, but had zero track support from his tuner or builder. He thought his transmission was failing.
I had a friend check it out—the trans was fine. The real issue showed up when I went up with him. His launch needed serious work, and because his Hellcat was so built, he had a long checklist of things to manage. In the heat of the moment, he forgot some of them. I pointed at him and said: “You are your problem.”
That’s why I always say: learn the basics before you build your Hellcat. Seat time and fundamentals matter more than horsepower. Too many tuners, builders, and parts vendors are happy to take your money, but they won’t be there when you’re struggling at the track. I also asked my friend to help him onto the track.
He was mad he spent all that money and knew his Tuner/Builder was out supporting other customers. He also said he has to get a lot more seat time and now realises that it was too much too soon.


I don't know much about the G-Force parts for Hellcats. But @fumanchu182 might chime in.

In 2014 while waiting for my Race car to be upgraded, I asked my husband since the warranty was done if he would send my 2010 SRT Furious Fuchsia Daily driver to HHP for a small build. It has a D1 Procharger and G-Force axels. I gave that car to my daughter Kate. She is a great Index racer and had made 1000's of passes and the G-Force back then were guaranteed for life. But, she races 11.50's it's a sweet spot for the 2010's Chase a 10.0 and lower, lots of race and break and adding parts.
That 2014 Tune and Build is still going strong. I know guys who used G-Force on SRT8 prior to Hellcats - bigger builds and they didn't hold up.

 

[Jon-MooredPerformanceLLC]

So the farther I go down this rabbit hole the more complex it gets, leaving me with more questions than answers.
1) There seems to be a lot of discrepancy in regards to red eye driveshaft, axel and differential failures depending on where you look, some say problems and some say no issue. It’s hard to know what to believe, but wheel hop induced by pilot error may be the biggest culprit?
2) reducing wheel hop may be achieved through various BMR or AAD products
3) A modified cradle 9” rear end and 1 piece aluminum drive shaft with stronger 35 spline axels should address some potential failures but may slow down a stock red eye if traction gains aren’t substantial
3) Do you add more power via a PCM and tune before addressing suspension or after
4) When someone says they aren’t interested in doing power modifications you know it’s just a matter of time before the disease infects them

On a side note I am in Canada and the 9”IRS kit with driveshaft would cost me about $20,000 + Canadian with taxes duties and fees and I can get it with an extra set of axels for $5,000.
For me to buy the AAD performance Drag Pack I am at $3,530 plus whatever duties and brokerage fees they charge me.
The BMR cradle lockout kit would be about $430
A one piece aluminum driveshaft about $2000
Performance developments diff brace $1000

So do you go with the 9” IRS and modified cradle and plan on doing a stage 1 or stage 2 upgrade next year, believing that will be the extent of your performance modifications, or skip the “deal” and put the $5,000 elsewhere?

Talking about a tune an issue you will have with your redeye is cat over temp. This can be fixed without removing the cats. No need to remove them. But it is a tune change. The car gets so rich it maxes out the injectors and opens the bypass to bleed boost as a safety since it sees the injectors are maxed. Typically, though a good tire. 305 or 315 (I would just the 315 on a 17in wheel) and a diff brace is where people would start. Like @Linda's Hell Cat said above a lot of hellcat people upgrade to the redeye shaft for racing. The aad will help with your 60ft. But I have cut a 1.2 without them with just e85 and pulleys and a 17in wheel. Putting the aad on will get you that more predictable launch. I will not talk you out of it it is an outstanding upgrade but is it required for a stock redeye at the track? No it isn't.

Long story short if I was you diff brace and a set of wheels and tires and go to the track. Personally I think you will want a tune but might as well collect data and have fun with the process. A tuned redeye with octane booster or 100 octane can do 9s I have seen it plenty of times with little to no modifications.
If time goes on and you want to start running a race fuel and pulley down then do the driveshaft. If you start chasing low 1.3 60fts do the axles.

 

[Speedy!]

Too many people will tell you to throw the kitchen sink at a problem that likely doesn't exist.

I raced my Hellcat for 8 years and have a stack of time slips an inch tall. Last pass was a 9.6 at like 146mph. Stock 2.62 diff and stock axles. I upgraded the drive shaft to a DSS 4" aluminum but the Redeye is stronger and I'd leave it a lone until it broke. Add a Per4mance Development diff brace and call it a day.

 

[2ndAmend]

Too many people will tell you to throw the kitchen sink at a problem that likely doesn't exist.

I raced my Hellcat for 8 years and have a stack of time slips an inch tall. Last pass was a 9.6 at like 146mph. Stock 2.62 diff and stock axles. I upgraded the drive shaft to a DSS 4" aluminum but the Redeye is stronger and I'd leave it a lone until it broke. Add a Per4mance Development diff brace and call it a day.

I tried to tell him that. But apparently he is enjoying this thread too much...

 

[Ta2ude]

I tried to tell him that. But apparently he is enjoying this thread too much...

I am not quite sure what you mean by this?
Should I have ended the thread after your reply and stopped trying to gather any more information from that point on ?

I did start digging deeper after your reply to this thread if that helps.

 

[2ndAmend]

No problem here, we all just want to help and/or be happy!

 

[Marc W]

My .02 Unless you’re going to build your motor north of 1000whp you do not need to spend all that money on a 9” rear with all the associated bits and pieces. My list would be…. Lock your cradle down. Secure your rear end with all the braces. Secure your suspension with the full AAD set. Replace your axles. My choice would be DSS. I don’t know about their current stuff but in the past there were a lot of unhappy G-Force customers. If you don’t already have a 17” wheel/tire setup…. I would advise going straight to a 15”. A 17 may get it done with the right prep but overall the 15 will be much better. With a stable (no hop) rear… a Redeye drive shaft stands a chance. If you want to go aftermarket…. PST Carbon Fiber. All that and pull some weight out of the car and you’re ready to go to the track and not embarrass yourself. You decide to start adding hp…. You’re ready for it.

 

[2ndAmend]

I am not quite sure what you mean by this?
Should I have ended the thread after your reply and stopped trying to gather any more information from that point on ?

I did start digging deeper after your reply to this thread if that helps.

We all have been trying to suggest that you just put on a DIRS and run it. Simple as that. No offense intended.

 

[Ta2ude]

Awesome I am glad to hear that and apologize if I am asking some of the same old annoying questions over again. I am new and I do appreciate the input.
Like I originally said at the start of this thread, I believed I could run my car basically stock, on drag radials without an issue. I do have one of the earlier versions of the diff brace that I installed several years ago now but it’s not the fancy one.
I was already looking into cradle lockout kits and the AAD stuff when
I came across what seemed to me to be a good price on what appeared to be a superior solution (9” kit and modified cradle) for less than the other stuff would cost me.
I ended up here and started a thread to see what I could learn and here we are now.
Once again I appreciate the input and just because I may still have some questions it doesn’t mean I am ignoring anyone’s advice.

Has anyone seen this guy on YouTube? He’s broken lots of stuff and on this video he shows how the diff brace tore out of the subframe

 

[DGatzby]

Take this solid advice from a guy happily married over 51 years....IT'S NOT A LIE ...IF YOU BELIEVE IT..feel free to lie to yer wife,,@ least twice a week..

Going on 51 years myself. He has solid advice.

 

[DGatzby]

Awesome I am glad to hear that and apologize if I am asking some of the same old annoying questions over again. I am new and I do appreciate the input.
Like I originally said at the start of this thread, I believed I could run my car basically stock, on drag radials without an issue. I do have one of the earlier versions of the diff brace that I installed several years ago now but it’s not the fancy one.
I was already looking into cradle lockout kits and the AAD stuff when
I came across what seemed to me to be a good price on what appeared to be a superior solution (9” kit and modified cradle) for less than the other stuff would cost me.
I ended up here and started a thread to see what I could learn and here we are now.
Once again I appreciate the input and just because I may still have some questions it doesn’t mean I am ignoring anyone’s advice.

Has anyone seen this guy on YouTube? He’s broken lots of stuff and on this video he shows how the diff brace tore out of the subframe

What else do you know?
Other mods, I see Nitrous posters on the wall? Power and tune? How was it set up to go? How was he launching it?

 

[Linda's Hell Cat]

What else do you know?
Other mods, I see Nitrous posters on the wall? Power and tune? How was it set up to go? How was he launching it?

When I saw the drag radials, I checked into Kelly’s Garage and found a video from 2022. At that time, I couldn’t determine what his horsepower numbers were.
If you click through to his YouTube channel, you’ll see that Kelly is someone who truly enjoys modifying cars. He’s been doing his own R&D and T&T for about five years, documenting what works and what doesn’t.

Currently, he’s running in the low 9s with a 3.0 Whipple supercharger—though that setup isn’t strictly necessary to achieve low 9s. My impression is that he’s probably chasing an 8-second slip. Some of his setbacks may come from not having all the supporting parts in place, or from using components that others avoid. For example, he experienced a built transmission failure. Personally, I would have invested in a Sipple Max Effort HP90 https://highhorseperformance.com/si...reak-demon-super-stock-6-2l-hemi/Transmission rather than a Pure.

Today, there are well-established packages for builds and tuning that combine proven parts and strategies. Vendors continue to innovate, competing to manufacture stronger components. But even with those advancements, there’s always R&D and T&T required to push the limits.
—Linda