solid exhaust , no flex

[dmiller]

i just finished connecting headers and side pipes on my 289 FIA. i'm concerned that there is no provision for flex. the engine can torque over in the engine mounts, but the exhaust is attached solid to the frame. this seems like a problem, broken bolts, cracked headers,

has anyone had these problems, or has anyone devised a method to allow flexing?

i'm thinking that unless someone has a better idea, i'm going to try to figure out someway to rubber isolate the side pipe from the direct connection to the frame.

[pgermond]

Although I haven't gotten everything together to experince your concern, I have consider the same thing. I don't know if a rubber (or some other material) would provide enough flex/give to be adequate. I would be interested in what your final solution turns out to be.
Good luck, Phil

427 Roadster
Southern Automotive FE
Toploader

Roseville (N.Cal)

[pgermond]

Although I haven't gotten everything together to experince your concern, I have consider the same thing. I don't know if a rubber (or some other material) would provide enough flex/give to be adequate. I would be interested in what your final solution turns out to be.
Good luck, Phil

427 Roadster
Southern Automotive FE
Toploader

Roseville (N.Cal)

[GeorgiaSnake]

Mine is stiff :) and I haven't had a problem.

Randy

Unique 289 FIA
Southern Automotive 396
Team III 16's
Brilliant Silver

[GeorgiaSnake]

Mine is stiff :) and I haven't had a problem.

Randy

Unique 289 FIA
Southern Automotive 396
Team III 16's
Brilliant Silver

[Brent]

I made rubber washers out of a conveyer belt to go between the frame and the exhaust. They are about .200 thick and really reduced the vibration. I have actually changed the trans mount by lifting the back of the trans high enough to get the studs out of the frame and the exhaust was still bolted solid.

Brent

[Brent]

I made rubber washers out of a conveyer belt to go between the frame and the exhaust. They are about .200 thick and really reduced the vibration. I have actually changed the trans mount by lifting the back of the trans high enough to get the studs out of the frame and the exhaust was still bolted solid.

Brent

[dmiller]

i think i'll try the rubber washer idea. thanks

[dmiller]

i think i'll try the rubber washer idea. thanks

[dmiller]

have given it some thought, my plan now is to get some 5/16 shoulder bolts, and some vinyl tubing that has 5/16 ID. slip the tubing over the shoulder bolt, just long enough to go thru the angle that attaches to the chasis. i'll drill the angle iron pieces out to accommodate the OD of the tubing. the bolt will pass thru the sidepipe welded mount, with the 1/4-20 nut to hold it all together. this will allow the pipe to flex around the vinyl and move forward and back along the shoulder bolt. i may have to grind the angle slightly to allow some clearance for forward and back motion. all of this is just night time planning, not actually done yet, so the application my result in some problems.

i attempted to put rubber between the chasis and the angle brackets, but wasn't happy with that.

[dmiller]

have given it some thought, my plan now is to get some 5/16 shoulder bolts, and some vinyl tubing that has 5/16 ID. slip the tubing over the shoulder bolt, just long enough to go thru the angle that attaches to the chasis. i'll drill the angle iron pieces out to accommodate the OD of the tubing. the bolt will pass thru the sidepipe welded mount, with the 1/4-20 nut to hold it all together. this will allow the pipe to flex around the vinyl and move forward and back along the shoulder bolt. i may have to grind the angle slightly to allow some clearance for forward and back motion. all of this is just night time planning, not actually done yet, so the application my result in some problems.

i attempted to put rubber between the chasis and the angle brackets, but wasn't happy with that.

[GeorgiaSnake]

I think you guys are over reacting to a preceived problem that doesn't exist. I have not had a problem and know of only one person that has. I think if you make the sidepipe a soft mount you will move the sress points to the header assembly. I would rather have a sidepipe bolt break than the header. Just a thought here.

Randy

Unique 289 FIA
Southern Automotive 396
Team III 16's
Brilliant Silver

[GeorgiaSnake]

I think you guys are over reacting to a preceived problem that doesn't exist. I have not had a problem and know of only one person that has. I think if you make the sidepipe a soft mount you will move the sress points to the header assembly. I would rather have a sidepipe bolt break than the header. Just a thought here.

Randy

Unique 289 FIA
Southern Automotive 396
Team III 16's
Brilliant Silver

[eliminator]

No problems on the 427 Cars, that big engine just shakes the whole car. Kinda like my Harley. I have heard of some FIA car problems in this area. The conveyor belt, or other material between the side pipe mounts and the frame works well but it is still a pretty solid mount. There are cars out there with thousands of miles on them with no problems.

Eliminator

[eliminator]

No problems on the 427 Cars, that big engine just shakes the whole car. Kinda like my Harley. I have heard of some FIA car problems in this area. The conveyor belt, or other material between the side pipe mounts and the frame works well but it is still a pretty solid mount. There are cars out there with thousands of miles on them with no problems.

Eliminator

[dmiller]

i appreciate your thoughts, and will do some more thinking.
thanks
doug

[dmiller]

i appreciate your thoughts, and will do some more thinking.
thanks
doug

[Okiesnake]

I also share GeogiaSnake's opinion.

[Okiesnake]

I also share GeogiaSnake's opinion.

[Tony Radford]

I've had problems with the side pipes on my car snapping the heads off of the front bolts that connect the side pipes to the frame. I quit replacing them because getting the bolt itself out of the frame is tough and they just break again anyway. The back bolts don't seem to be a problem. This last time, the mounting tab that is welded to the side pipe snapped off and had to be rewelded. When the bolt head comes off, a loud high-pitched sound develops as the pipe tab vibrates against the frame. I wedged 1 inch squares of felt between the front sidepipe tabs and the frame (leaving the bolts out) and just rely on the back bolts to hold the pipes to the frame. Doesn't seem to be a problem. I don't see any way to leave both bolts in and allow for any flexing of the system. When you crank down hard, the motor is going to twist. In the case of my 427 SC, the side pipe tabs fit hard against the frame. I had to pry the pipe away from the frame to get the felt pieces in place.

[Tony Radford]

I've had problems with the side pipes on my car snapping the heads off of the front bolts that connect the side pipes to the frame. I quit replacing them because getting the bolt itself out of the frame is tough and they just break again anyway. The back bolts don't seem to be a problem. This last time, the mounting tab that is welded to the side pipe snapped off and had to be rewelded. When the bolt head comes off, a loud high-pitched sound develops as the pipe tab vibrates against the frame. I wedged 1 inch squares of felt between the front sidepipe tabs and the frame (leaving the bolts out) and just rely on the back bolts to hold the pipes to the frame. Doesn't seem to be a problem. I don't see any way to leave both bolts in and allow for any flexing of the system. When you crank down hard, the motor is going to twist. In the case of my 427 SC, the side pipe tabs fit hard against the frame. I had to pry the pipe away from the frame to get the felt pieces in place.

[excelguru]

Mine is also pretty stiff and I never use rubbers... wait a minute... what are y'all talkin' about? :D

Keith :)
Unique Motorcars (http://www.uniquecobrareplicas.com)
Southern Automotive (http://www.southernautomotiveengines.com)
Bruce Bunn (the painter) (http://www.jodecoautobody.com)

My Photo Album (http://members5.clubphoto.com/keith355593/owner-429c-1.phtml)

[excelguru]

Mine is also pretty stiff and I never use rubbers... wait a minute... what are y'all talkin' about? :D

Keith :)
Unique Motorcars (http://www.uniquecobrareplicas.com)
Southern Automotive (http://www.southernautomotiveengines.com)
Bruce Bunn (the painter) (http://www.jodecoautobody.com)

My Photo Album (http://members5.clubphoto.com/keith355593/owner-429c-1.phtml)

[Mike Geddes]

Keith...sounds like we got the same train of thought.
Mine's been stiff for 11 years with no rubbers.

Doug....I think it's the Precision Machinist in you coming out with all these 'tight' to 'zero' tolerance ideas.....Remember the engine mounting bolts.????

Mike

Mike Geddes

[Mike Geddes]

Keith...sounds like we got the same train of thought.
Mine's been stiff for 11 years with no rubbers.

Doug....I think it's the Precision Machinist in you coming out with all these 'tight' to 'zero' tolerance ideas.....Remember the engine mounting bolts.????

Mike

Mike Geddes

[dmiller]

i compromised, i put a piece of rubber gasket under the chasis between the angles that the pipes bolt to. didn't use the shoulder bolts, will do that if these fastners shear.

mike, glad to have you back in the america's. hope trip home was good.

i'm making slow progress, got wiring harness on and now wiring up headlamps, tail lamps.

i've got to replumb the fuel line, and then body back on the chasis.

[dmiller]

i compromised, i put a piece of rubber gasket under the chasis between the angles that the pipes bolt to. didn't use the shoulder bolts, will do that if these fastners shear.

mike, glad to have you back in the america's. hope trip home was good.

i'm making slow progress, got wiring harness on and now wiring up headlamps, tail lamps.

i've got to replumb the fuel line, and then body back on the chasis.

[Mike Geddes]

Well thanks Doug.....the trip back home to the UK was great.
Did not see any Cobra replicas at all in the two weeks I was there..saw a whole mess of original and replica Lotus 7's and 2 TVR's that would make your eyes water.
Cobra's will not fare well in London...the average speed thru the city is 3 MPH...( I note in the gear ratio talks, top ends of 100 to 160 being talked about.)....The speed Camera's on British roads would eat you alive.
Maybe thats why we live here.(Yes, I do live North of the Mason Dixon Line.).....and North of the border.
Anyway ...glad you got your side pipe issue resolved.
Mike


Mike Geddes

[Mike Geddes]

Well thanks Doug.....the trip back home to the UK was great.
Did not see any Cobra replicas at all in the two weeks I was there..saw a whole mess of original and replica Lotus 7's and 2 TVR's that would make your eyes water.
Cobra's will not fare well in London...the average speed thru the city is 3 MPH...( I note in the gear ratio talks, top ends of 100 to 160 being talked about.)....The speed Camera's on British roads would eat you alive.
Maybe thats why we live here.(Yes, I do live North of the Mason Dixon Line.).....and North of the border.
Anyway ...glad you got your side pipe issue resolved.
Mike


Mike Geddes

[pbrown]

So would a better design be to just remove the front sidepipe mount and just use the rear? That's what SPF cars do. Perhaps relcate or alter the rear mount so that there could be a rubber isolator. Thoughts?

--Patrick

[pbrown]

So would a better design be to just remove the front sidepipe mount and just use the rear? That's what SPF cars do. Perhaps relcate or alter the rear mount so that there could be a rubber isolator. Thoughts?

--Patrick