working on a 51 with a "Gambino style" notch and 4 link. the owner has the Fenton cast iron V8 "quad exhaust" headers and wants to run 4 pipes all the way out the back under the rear end. straight pipes (no bends)all the way to the bumper and under the rear end. as it is set up right now you can not remove the rear tires without dropping the shocks and bags,(with stock 5" rims and skinny tires) so he will also have to remove the exhaust if he ever gets a flat out on the road. sounds like a big pain in the ass to me. if a person is notching and bagging a car you have the trunk floor and inner wheelwells all cut up anyway, it would not take much more effort to run the pipes over the rear, even if a car is going to have 4 pipes. ""Tight and outa sight is a "new" concept"" .... a well done dual exhaust has been a staple of Hot Rodding since the beginning of Hot rods. not seeing it as anything new.
A year after I bought my 54 Chevrolet, I added Dual Carbs, and split Fenton Manifolds. Had dual exhaust run with Smitty Glass Packs. It was a nice touch for the car. The next year I saved up and lowered the car. Did dropped uprights and cut a coil in the front and 3 inch blocks in the rear. Car always hit bumps hard in the back of the car. Living In Pennsylvania the roads suck. Some bumps you could feel go through your body. So after a few weeks, the car starts to run rough. Back pressure is stronger out one side of the exhaust pipe. Spent the summer, tearing carbs apart, adjust carbs, messing with timing, chasing a problem I couldn't figure out. Next summer decided I wanted flame throwers on my exhaust. Lift the car up to start the project and noticed the problem. Exhaust pipe above the axle was crushed in the shape of a C. Hit a pothole, rearend came up and smashed the pipe almost closed. I cut the tailpipe off, had a new one bent. Guy bending the pipe had a hell of a time getting it so it wouldn't smash again. That pipe cost almost as much as the dual pipes did to start with.
Sure, why not. IRS Vettes all go under. (I did it on my 41 Willys 10 yrs ago, and to this day no issues).Just make sure the shocks are at a length that keeps all the weight of the rear end off the exhaust when jacking up the car from the body/frame
That's not hitting bumps hard, that's bottoming out on your suspension. A design flaw in the suspension alterations.
For a bunch of years Volvo 240s ran an "under axle" exhaust. Just flattened a little right under the axle http://www.ipdusa.com/uploads/images_products_slideshow/fullsize_1771.jpg yes, when the car is lifted by the body the dangling axle pulls the exhaust downward . The stock rubber o-ring mounts are pretty stretchy. The rear sway bar jogs upward on the right side for extra clearance, and the exhaust runs pretty close to the center of the car, so one wheel dropping into a pot hole is less likely to bonk the exhaust with the axle
In the '60s we used to run scavenger pipes inder the rear. I cannot say no proiblem but it was the style. here is the deal your rear has a punkin right? it is bigger around than the axle housing so if theory if you can the exhaust right up against the axle housing it would not get smushed. now here is the rub, unless you mount your rear solid you cannot run your exhaust right up against the tubes. the rear travels so you have to allow for travel as your pipes don't travel.
Not a HAMB type deal, but a friend of mine ran the tail-pipes under the rear on his street-strip car. He'd been running the car with open headers and collector extensions, and it had always hooked hard and ran low 1.50's. The first time he ran a street-legal deal, he just left it corked up, full tail-pipes and all. All of a sudden, the car wouldn't hook. It would lift, hook for the first foot or so, then the nose would drop, tires would spin, and the car would pogo all the way past the tree, and clock mid 1.70s. A bunch of us were standing around speculating on what was causing it, the general consensus was that it was making more torque with the full exhaust, just like it said in some magazine articles. I told everyone, they were completely out to lunch, that wasn't what was happening at all, and they werent watching the car. Told them to go look at the tops of the tailpipes where they passed under the axle, and the bottom of the axle tubes. Sure enough, there were witness marks on top of the pipes and the bottom of the axle tubes. When the car launched, and the rear suspension started to push the rear end down, the rear axles downward motion was being stopped by the tailpipes, the car would unload the tires, spin, the suspension would settle, and the cycle would repeat. I cut the tail-pipes off with a hack-saw in the pits, and the car went right back to low 1.50's. Shows what happens when you let pre-conceived ideas interfere with what you are observing in the cars behaviour.
I had a 67 Triumph TR-4A with live axle, (off topic) had the frame under the axle. Exhaust pipe ran right along the frame, car had fairly large wheel openings so when you jacked it up the axle laid on rubber bumpers on topside of frame and wheel was easily removable. Just something to think about instead of cutting the shit out of your frame to make "C" notches!
If you run the pipes under the rear end, just make sure you are at the ride height you are going to stick with. Any ride height change you make will change the relationship between pipe and rear end. If your exhaust pipes go over the rearend, that relationship will never become a problem. Been there, done that.
yeah Tommy, had a 54 Del Ray with split manifold, heated the front springs some (I was 15) and ran the scavenger pipes with glass pacs. Later, cut the bells off the ends and used the chrome pipes behind the header collectors back to the mufflers on my Firebird.
The axle has to drop far enough that the tire can slip between the fender and brake drum. On a low riding car with wide tires, the axle will have to travel down quite a ways from ride height to get the tire out.
I would never do it so I don't know, but I've heard guys build these lowered contraptions and have to disconnect the shocks to get the tires on and off any way.
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