How much clearance (frame 2 axle) needed on P-touring car?

Happy 4th of July fellow Mopar heads!

I am mocking up the rear axle housing of my pro touring '72 Satellite project. My new wheels are Show Wheels Streeters. 20 x 10 rear and 18 x 8 front. They are Awesome wheels! I plan on putting 315/35/20 tires out back, but need some advice as how low I can go. The rear suspension will be a custom fabbed coil-over 4-link. If I position the axle housing where I'd like see the top of the rims above the wheel well opening, the top of the axle housing is only 3 inches below the frame rail. The rubber stop on the frame is 2'' tall... leaving only 1'' of suspension travel. Is that enough clearance? I've looked for pics of other P-touring Mopars, and no one is notching their frame rails in the ones that I have seen thus far. HELLLLLLLP!!!!

Thanks!

P.S. I wish I could post some pics, but I'm having computer issues. I hope to solve them soon and start a build thread to show case what my brain causes me to do with power tools!

Rubber bumpstops can be trimmed or replaced with shorter ones. I doubt 1" of clearance is enough, unless you are running seriously high spring rates.

I dunno what stock clearance is but I'd go close to that.

Thanks! I forgot to measure the stock clearance before I removed the leaf springs. I did however bolt the wheels on when the car was at the stock height, but it didn't have that low-slung pro-touring look. This body style with the bulged out wheels wells makes this car perfect for that type of modification. I hope the chicks dig it when it's done! Although, I'll let them check it out right now... hah!

This is bizzare to me. There are thousands of pro touring cars running 19'' and 20'' wheels and many of them have installed bolt-in rear 4 link kits, which means they haven't altered the arch of their frame rails. Those cars are prowling the streets with lowered ride heights as I have mocked up on my car. I have 1'' clearance from the top of the rear axle housing to the rubber bump stop. Unless I am dealing with faulty eye sight or something far bigger than my brain can fathom... those guys must be bangin' their frames and rear ends together after filling their gas tanks, and bellies with lunch in some cases!

Can anyone explain this strange phenomenon to me before I break out the plasma cutter or perhaps lose my mind?!

1" is not sufficient. Many of the cars you speak either have custom frame rails or the stock frame rail is notched and reinforced. You can also relocate the bump stop to allow more clearance as well.

If lowering that much, you will also need to clearance/raise your trans/driveshaft tunnel to clear the driveshaft/differential.

Cool! Thanks! My drive shaft is out, so I didn't look for clearance problems there. I think fabricating all new frame rails instead of notching the originals would be stronger and better looking too! Hopefully car show spectators will be able to see all the cool custom work in the reflection off my polished wheels!

Wait a Mopar minute! Moparts member "Keepat" is building an amazing pro touring Bullit '68 Charger as seen in the "projects and survivors" section. His car sits very low with RMS suspension kits, but he has no rear frame rail notches, and no drive shaft tunnel modifications, except for the transmission area.

The bottom of my rocker panels now (minus the pinch weld) are 9'' from the ground front to back. I don't think that is extremely low. Can anyone provide me with the factory rocker panel height form the ground on their '71-'72 Road Runner or Satellite?

Appreciation in advance! Take your time... no wait! Please hurry!!!

Guess I should try a separate post for the rocker panel measurement.

I was looking at a '72 Charger at a local show yesterday. He had some tubular front k-member and suspension installed and I commented that he only had an inch of space between the frame and lower a-arm. He said the suspension was VERY tight.

He was one of those guys that makes you scratch your head ... decent car, lots of mods that appear to be garage-done but when I asked whose front end it was all he could say was "some company in California". The motor plates blocked the front of the heads so I couldn't tell whose they were and he couldn't tell me either ... "a buddy built the motor" he said. I was going to ask if he know how to open the door but I figured that was just being too much of an ass!

Hey man! That's my little brother you're calling an a-s-s!

JUST KIDDING! I'll be happy to tell you and anyone else whatever tid-bits you'd like to know about my ride! Except of course my secret trunk latch that I invented!

A lot of these guys are like the one Stanton encountered. They chose that wheel and tire/suspension combo strictly on the basis of how "cool" they think they look with it and IF they are even aware of the ramifications of 1" suspension travel (or anything else), it is just an accepted cost to look "cool".

IMHO, the only way to get that "cool" look and still have something more useful than static sculpture, is to go with a Ridetech air system.

http://www.ridetech.com/store/musclecars/?subcats=Y&features_hash=V298.V328

I've seen this system in action on an autocross track in their 66 Chevelle and I was astonished to put it mildly.

When it's time to look cool, just push the Cool Button and it's in the weeds.

Kevin

My charger, currently in mock up, has a T56, RMS front/rear, Moser D60, and V10. I'm running 18" wheels which fill the wheel well nicely. i have 5" of clearance at the bottom of the car (rockers).

Car is definitely lowered. I still have more than 3.5" of clearance between the axle and frame rails. Based on my shocks and spring rates i could lower it another 1.5" still with no significant issues.

I upgraded to a 4" Aluminum driveshaft and also pushed back and raised the V10/T56 a bit. As such, i completely cut out the transmission tunnel and raised it about 4".

All things being equal, going with larger wheels will increase ride height but won't affect the axle to frame rail distance. What you are finding out is that the larger wheels necessitate lowering the car more so that it doesn't look like a wagon... as such, your loosing that much needed space between axle and frame rails.

Ah haaa! Now I see thanks to you and your 18'' wheels, that my 20'' wheels are the culprit! All along I felt like I was mocking it up wrong because without tires on my rims, I was using wooden blocks in their place. The problem was there, but I didn't want to see it.

Now I feel better about modifying the frame rails, and drive shaft tunnel.

Thank you!

I appreciate your opinion... it's how we learn. Things like Ride tech and RMS suspensions are not in my budget, thus I must fabricate everything myself. However, I prefer to have fun designing and making things myself and receive all of those pats on my back from those who giving praise. That's my cool button moments!

Sash, the difference between your ride and the ones you've seen is that you plan to actually drive it beyond a trailer and that you are thinking ahead about how that'll work out for you. Good job.

Wow! Thanks Super Cuda! Cool button! Cool button! Yep, I'll drive it a lot! That's why it will have a mild small block instead of a 600-1000 hp stroked big block. NOT THAT THERE IS ANYTHING WRONG WITH THAT! I just want a nice easy to use, maintain and afford machine that drives the chicks wild!

Maybe in the distant future when I find a Hell Cat Challenger in a scrap yard, I'll get the "Red" key out of it so I can have 707 hp on tap! He-he-he!

One thing I learned years ago, when this stuff was cheaper and easier to find, was that build a car should be done backwards from most.

Suspension, brakes, rear axle, trans then engine.

Learned the hard way also never trust the brakes on a junkyard rearend, especially with a single reservoir master cylinder.

OMG! How any of us lived through our teens and twenties is a funny but scary thought! That would make a great thread... people sharing their wild-n-crazy stories from their youth! Although, I am in my 50's now and still I continue to put myself in danger! Why just yesterday, I gave myself a concussion while working on my Satellite. Honestly! That's why I'm inside messin' around on Moparts while I recover!

I used to dirt track race those stock body early 70s Mopars. We ran the old wide dirt track racing tires. 11" tread width, tall side wall 15" wheels. Probably had about the same tire diameter as your 20" wheels with the short sidewall tires.
Dirt tracks are usually pretty rough, and racing shocks of those days were pretty stiff. When we kept all 4 tires on the ground, we only had a total of about 3" of rear shock travel, that would be both up and down or 1 1/2" each direction from static position. The front shock travel was much more, but I wonder of you will be cornering as hard as we were (banked corners).

The stiffness of your springs and how much "bounce" your car experiences will determine how much suspension travel you will have. With proper springs and proper shocks, I would think 2" of clearance between the axle and the bump stop should be enough. You just have to be sure that 2" of clearance is at ride height with a full tank of gas, and the average passenger and trunk load you intend to carry on board. You can't start at 2" then add the gas, the girls and all your tools in the trunk.

Another note, we had issues with side to side movement even with leaf springs. Be sure you have a rigid parhard bar on the rear. Big tires will move that rear end side to side on turns, especially if your sliding. Gene

Two big assumptions in that; that they haven't modified the rails and they are actually driving their cars.