The Jalopy Journal
Discussion in 'The Hokey Ass Message Board' started by ratrod0, May 5, 2012.
is that what it is called (Dead mans purch) if it is where can I get one
Do you mean dead perch, as in a spring perch on a solid axle with no shackle?? Generally used on one side only and is usually used on a street driven vehicle to eliminate the need for a front panhard bar.
Try PERCH instead of PURCH.
A dead man's perch is a joint on a leaf spring that doesn't have a shackle. Spring is bolted straight to the axle/bone at one end only. Acts kind of like a panhard rod to locate the axle side to side.
edit: beaten to it
This is what I'm talking about
Here is a Dead Perch,.. actually,.. they were originally developed from the oval track,.. Speedway use to sell them. I never actually seen spring failure from using a dead perch, But have heard a number of stories of spring eye failure while using these on the street.
PLEASE NOTE : I have no proof of this, and talk is cheap,.. just passing along the hear-say. Judge for yourself,... You might want to contact Speedway and ask if they still sell them,.. And if they don't , why they quit selling them.
perch is a mighty fine tasting fish too.
So-Cal shows a stainless version in their online catalog but i have no experience with using a dead perch so I can not advise one way or another on their utility.
That's what I was thinking..... Damn. I'm hungry again.
ahh, simple minds think alike.lol.
Morton & Brett offered them for Model T Dirt Cars in their January 1929 catalog. They placed them on the left or drivers side of the axle. Bob
And if its off it might be a dead mans perch !!!
I was surprised to see them being sold again because the Deuce Factory had them years ago and when I called to buy one they said they discontinued them because "some people didn't know the right way to use them", whatever that meant. I didn't know if there were some handling issues or what.
As I understand it they are mainly used when you are running cross steering and not really needed with traditional early Ford type steeriing.
sumthing smells fishy.
If used with cross steering, they have to be installed on the left. With side steer, they are usually installed on the right. If you install them on the right with cross steer, it magnifies any bump steer issues.
Ah, that might be what they were talking about. Makes sense.
So-Cal speed shop offers a stainless dead perch. I have one on my international.
I know that Dick Spadarro doesn't like them at all, "In reply to the question regarding a use of the "dead man" style ridgid perch on a street driven car my response would be "DUMBASS ENGINEERING". These things have been marketed for quite a while, undoutably many people have purchased them assuming that they would save time, money or cure a design engineering defect that they could not figure out. Well they only half work and might as well be considered band aids.
As others have pointed out these perches have been used on racecar applications for years, in fact this principle is still applied today in some instances. For use on a street car it has limited or no merit for useage.
While this perch would locate the front end of a race car turning left, its application on a road driven vehicle that requires some suspension travel to promote a good ride leaves a lot to be desired. Originally the dead perch was used to eliminate the use of a panard rod to control the lateral movement of the spring suspension in the chassis. This works ok in a race car but not on a street car.
The positioning of a fixed spring point eliminates the ablity of the spring to flex. Ridgid mounting of the spring at the u-bolt combined with the fixed mount at the perch virtually eliminates any movement in the spring thus transmitting all the flex movement of the spring to the shackled side and probably eliminates 50% of the spring characteristics that help determine a smooth ride. This basically has the spring working on one side but not the other. For proper spring action the ends of the spring must be flexible. In many cases steering design requires a panard mount to locate the front axle for stablity. I am sure that those installations using a dead perch were changed to a standard flexible shackle perch the ride characteristic would improve greatly.
To further make my point on the elimination of dead perch use, I'll use this as an example. Take a carpenters hand saw, place it flat over an opening where the ends can be fastened or held securely. Clamp or hold the ends of the saw tightly and attempt to push in the center of the blade down to get a deflection, this should be very difficult. Now unclamp the ends and repeat by pushing in the center, the deflection is almost instant. This is the same way your spring works when going down the road. The dead perch eliminates the spring action and while it might cure some handling problem, creates a much harsher ride and hides a defect. Just say NO to dead perches before you are."
But I've had one on my 32 coupe for 8 years now with Vega cross steer and a Posies spring with NO ill effects.
do you mean dead mans purse?
Maybe a gay guy in Iran can tell you.
Dead man - check
Dead perch (fish) - check
Dead perch (auto) - check (it's "dead" because it doesn't move like a shackle)
Dead man's curve - check
Dead man's perch - nope
Dead man on a porch - every now and then. GN
hotroddon, which side is your dead perch mounted on? passenger or driver side?
Driver's side, same as steering box
I would think there would be less bumpsteer if mounted on the passenger side. The way the drag link pushes on the steering arm, it would seem to cause more side to side movement of the axle to frame, ex. cornering in a tight turn. I guess as long as this lateral movement is minimized, it shouldn't matter what side it mounts to? Or I'm I totally wrong in my way of thinking?
What is the purpose?
In place of a Panhard bar
It seems a dead perch has the potential to get half your transverse spring working as a panard bar.
What has always had me curious is, do you or dont you need to have the spring main leaf slightly shorter by about 3/8" on the dead perch side to balance things up.
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