Official 25.3 stock suspension Regal build

[Dusty Bradford]

I'm gonna document the changes my car is currently going through here. I have taken it from a V6 Regal bought from an old lady, to a low 8 second street cruiser, to a 7 second street cruiser. Now with the big block it's capable of 7.20's around 195mph while still maintaining the street car appearance and only using an 8 point cage. I have always tried to compete at 200-300# over min weight. Well time has come for some serious changes. The stock chassis was a becoming a bear to handle. I have always shifted the car myself, trying to fight the car and change gears has become unsafe so I'm upgrading to a 25.3 chassis and the car will look drastically different on the interior.

The seats will be aluminum but covered in material, the back seat will be gone to make room for the cage needed at this level. The console will be gone so I can save weight and utilize an air shifter so I can keep both hands on the wheel. The ride height will be lowered to get the ic and cg down. The factory panel the upper control arms bolt to will be replaced with the "g-box" from David Lemmond. It's a much stronger steel piece that won't risk being twisted or broken with better ic adjustability. I will still retain the stock location springs and shocks but the heavy factory spring perch is gone and replaced with a much lighter spring locater attached to the roll cage. So far I have lost 150# of raceweight. Front fenderwells have to go to make room for snout bars to help take the flex out of the front frame section.

Pics of all work will follow.

 

[86brick]

Thanks for the informative write-up on your car Dusty. I think a lot of people really don't know exactly what it takes to make a car work at this level especially on Drag Radials and stock suspension so it is cool to see someone like you willing to share info as well as put up pics in an effort to show all of what goes into a car at this level. I look forward to seeing how it turns out!

 

[Dusty Bradford]

I was curious myself just how fast a true stock suspension car can go so I didn't want to make any changes until I felt the limits had been reached. I know the car would run 4.70's as it sits. The 1.26 60' times I finally got Sunday would have put the car in the 4.74-4.76 range but the electrical issue kept me from getting those passes. The new wiring system will be simplified so I can more easily find issues like that.

The new suspension will be something people don't usually see by keeping the stock location springs and shocks but it's something I want to try. Many more pics will be coming next week. We're moving pretty quickly, just waiting on tubing.

 

[Bent6]

Welcome to the 25.3 club. I don't think many on this board have a clue what goes into building a chassis at this level. It's been an interesting journey for me so far. Lot's of little intricacies for the 25.3 cert. We managed to keep the back seat area open in my GS in an attempt to keep it "street" car but we've gone to extra lengths to maintain the rigidity underneath.

Is Lemmond doing yours? I assume you're going to the same extent of Stacks Monte Carlo?

 

[Dusty Bradford]

Welcome to the 25.3 club. I don't think many on this board have a clue what goes into building a chassis at this level. It's been an interesting journey for me so far. Lot's of little intricacies for the 25.3 cert. We managed to keep the back seat area open in my GS in an attempt to keep it "street" car but we've gone to extra lengths to maintain the rigidity underneath.

Is Lemmond doing yours? I assume you're going to the same extent of Stacks Monte Carlo?

Nothing as far as Stack's. This will be more along the line of Chad Henderson's Regal. I was going 25.5 but I hate the rear quarter panel buckling the Regal is known for so I wanted all the strength in that area I could get. So 25.3 it is. This has allowed me to skin the rear frame rails all the way down to the rear rail for a lot of tire clearance.

 

[John Wilde]

Thanks Dusty, now I don't have to beg for updates.

 

[Dusty Bradford]

Thanks Dusty, now I don't have to beg for updates.

If all the stuff already cut out hasn't been put in a dumpster I'll have a pic of all that early next week.

Lots of things you don't think about really adds up. Since the 25.3 has tubular rear frame rails you can save a lot of weight in the stock rails alone. Just by cutting off the old 1/8" plate I had used to box in the frame notch, you save 15lbs. We have taken about 30-40lbs off the rear frame section from just the back seat to the rear bumper.

The stock rear bumper with parachute bracket was 63lbs. This was a large part of the wheelie issue and is why I had to have 40lbs strapped on the nose of the car. So we lost 100lbs with that change alone.

 

[BlownV6]

Subscribed!! Make sure you get that passenger seat in there REAL GOOD!!
Thanks for for posting all this info for all to see. This is going to be verry cool!
Thanks Mike

 

[turbobuick]

ISince the 25.3 has tubular rear frame rails you can save a lot of weight in the stock rails alone.

Might want to check but I'm pretty sure the spec only requires tubular rear frame for unibody constructed cars that cut out the rear floor pan. Mine is near completion and will cert probably next month and I still have a full frame end to end. If you run a factory firewall and floor pan most of the additional spec over a 25.5 is in the passenger compartment, x-braced doors roof gussets everywhere etc.

For G-body cars it isnt much more than the 25.5. Underneath the floor and behind the main hoop it is essentially the same as a 25.5. We added some of the additional diagonal bars underneath. I cut the floor pan out firewall to taillight panel and dropped the body onto the frame. I am buying a one piece floor pan from Summit and splicing it in after the cage is complete. It was pretty easy to do and really made everything easier to fit and we have 360* welds on everything.

 

[Dusty Bradford]

Might want to check but I'm pretty sure the spec only requires tubular rear frame for unibody constructed cars that cut out the rear floor pan. Mine is near completion and will cert probably next month and I still have a full frame end to end. If you run a factory firewall and floor pan most of the additional spec over a 25.5 is in the passenger compartment, x-braced doors roof gussets everywhere etc.

For G-body cars it isnt much more than the 25.5. Underneath the floor and behind the main hoop it is essentially the same as a 25.5. We added some of the additional diagonal bars underneath. I cut the floor pan out firewall to taillight panel and dropped the body onto the frame. I am buying a one piece floor pan from Summit and splicing it in after the cage is complete. It was pretty easy to do and really made everything easier to fit and we have 360* welds on everything.

We're building it as if there are no rear frame rails. It will have bracing from the main hoop to the tail lights similiar to an o/l 10.5 car. We're going beyond spec.

 

[Dusty Bradford]

Subscribed!! Make sure you get that passenger seat in there REAL GOOD!!
Thanks for for posting all this info for all to see. This is going to be verry cool!
Thanks Mike

It will be in better than before:biggrin:

 

[86brick]

Dusty, you plan on running the big 30" tall radial on the car after it is 25.3?

 

[Dusty Bradford]

Dusty, you plan on running the big 30" tall radial on the car after it is 25.3?

I'm going back to the 295/65 which is a 30" tire. I won't have enough room for the 315/60 that everyone else runs unless I narrow the rear some more. I won't know what all needs to be done there until I get the new rear up in the car and mocked up. At this point though narrowing the rear enough to make the current wheels fit with the 315 is still an option.

 

[Red C5]

Thanks for the great thread. My GN is welded to the chassis table for a 25.3 build up as well. How light do you think you can get the car? I was hoping to get down about 3000 lbs. I have to retain rear rails for the class.

Really looking forward to more updates.

Peter

 

[Dusty Bradford]

A pic of the G-box by David Lemmond and a shot of what's left of the frame rail. We ground all the old plating off of it from the initial frame notch and hammered it flat to take the factory curve out of it. Makes a good bit of room for a 315/60 if needed. Do it once and be done with it. Rules call for the stock rear frame rail to be in place, notching is allowed.

I won't be worried about pulling the factory welds off the factory control arms mounts. This piece is built on a metal break then the metal caps are welded on the end. Plenty of adjustment holes to get the ic where you want it. The cage will be tied into the box to make it all super strong.

 

[Dusty Bradford]

Thanks for the great thread. My GN is welded to the chassis table for a 25.3 build up as well. How light do you think you can get the car? I was hoping to get down about 3000 lbs. I have to retain rear rails for the class.

Really looking forward to more updates.

Peter

I have to run at 3250# and I'll be lucky to get that light but that's the goal here.

To get to 3000# I'd need carbon doors and trunk lid for sure. I will never put Lexan in place of the glass.

 

[lazaris]

Dusty, your allowed to change the stock mounting points on the chassis in that class? I was having a hard time deciding what spec I was going with. I wound up going 25.5 to keep the weight down.

 

[turbobuick]

Dusty, your allowed to change the stock mounting points on the chassis in that class? I was having a hard time deciding what spec I was going with. I wound up going 25.5 to keep the weight down.

There are a few bars I would use a larger diameter for if building a 25.5 in case you want to go to a 25.3 later. Off the top of my head its the door xbars and the dash bar have to be a larger diameter. I have all the differences written down in my spec book and can look them up for you but your chassis guy should know. If keeping a factory floor pan and firewall there isnt really much difference in the two specs. The roof has to have an x-brace and some additional gussests. The larger door bars with some more gussets. Outside of the that there is little difference

Neither spec has any requirements outside of the drivers safety cage. Anything rear of the main hop is up to the chassis builder. I was able to maintain the factory frame and mounting locations but still tied everything into the cage.

Looks good Dusty. I thought about doing the UC mounting locations like that but I think I would run into some issues at some of the local races I plan to run.

 

[lazaris]

There are a few bars I would use a larger diameter for if building a 25.5 in case you want to go to a 25.3 later. Off the top of my head its the door xbars and the dash bar have to be a larger diameter. I have all the differences written down in my spec book and can look them up for you but your chassis guy should know. If keeping a factory floor pan and firewall there isnt really much difference in the two specs. The roof has to have an x-brace and some additional gussests. The larger door bars with some more gussets. Outside of the that there is little difference

Neither spec has any requirements outside of the drivers safety cage. Anything rear of the main hop is up to the chassis builder. I was able to maintain the factory frame and mounting locations but still tied everything into the cage.

Looks good Dusty. I thought about doing the UC mounting locations like that but I think I would run into some issues at some of the local races I plan to run.

Yes and those gussets have to be 1" diameter which is pretty big. They also want to see significant support and added bars behind the driver in the rear area which is not required for the 25.5.

I know some of the drag radial and stock suspension classes do not allow you have additional mounting points on the chassis end of the control arms.
Maybe in outlaw radial they are.

 

[Dusty Bradford]

This will cert 25.3 when finished. We're just going overboard with the cage from the main hoop rearward to make sure nothing flexes.

We can use adjustable mounts. The Mustangs can use the S-box with multiple holes, Racecraft and many others sell adjustable upper and lower mounts for the Mustangs. Once we all laid down and looked at most of the cars rolling through tech, it was obvious majority of them had done something for adjustability. Some had even cut the stock mount and relocated it so they only have one hole. The middle hole on this box is in the stock location.

It's alot of trouble but someone always finds away around the rules. If you knew you needed your mount 1" lower but could not use adjustable mounts. You cut the stock piece out between the frame rails, move it down 1" and weld it back in. Someone will go through that much trouble so the guys trying to keep the mounting locations stock have good intentions, but the hard core guys will go around it anyway. They just gave up in Outlaw Radial and allowed multiple mounts.

Some classes require the Mustangs have the control arm in a particular hole on the S-box. For this reason David put the center hole in the stock location in case it was ever specified.