(Note: LANDRACING.COM donations are not tax deductible)


This is a public forum. The opinions expressed here don't
necessarily reflect the feelings of The Folks That Run The Site (that's us)
unless we explicitly say so, ok?


Author Topic: Watts linkage instead of panhard bar  (Read 17632 times)

0 Members and 1 Guest are viewing this topic.

Offline 1977MGBV8

  • New folks
  • Posts: 14
Watts linkage instead of panhard bar
« on: December 25, 2007, 03:28:20 PM »
As a newbie, trying to get my hands around some of the concepts for this kind of racing I am wondering why don’t I see more Watts linkages instead of panhard bars (link attached to wikapedia: http://en.wikipedia.org/wiki/Watt's_linkage)? I know that suspension travel is short ~1 inch on the salt and that a 24” panhard bar moving up/down 1 inch would move the axle about 0.03” laterally  which is a very small amount but in a front end suspension application  this might have an impact of bump steer conditions.  For the rear end (assuming this is the driven axle) I could understand the added complexities due to changing out the gears though this too could be resolved.  Any thoughts or comments would be appreciated.

Offline Rex Schimmer

  • Hero Member
  • *****
  • Posts: 2433
  • Age: 77
  • Location: Fulton, CA
  • Only time and money prevent completion!
Re: Watts linkage instead of panhard bar
« Reply #1 on: December 25, 2007, 03:40:56 PM »
I think that you "hit the nail on the head" regarding the simplisity of the panhard rod for locating an axle. If you make it long enough and don't have much travel then it doesn't do much steering on either end. I have used watt links on several road racing cars that I helped build and race and they had 9 inch Ford rear axle assemblies and I think for that application the watt is the best way to go but for the salt a well designed panhard is simple and easy.

Rex
Rex

Not much matters and the rest doesn't matter at all.

Offline willieworld

  • Hero Member
  • *****
  • Posts: 1818
  • Age: 75
  • Location: 921 chicago ave modesto ca. 95351
Re: Watts linkage instead of panhard bar
« Reply #2 on: December 25, 2007, 04:12:24 PM »
half as much to buy half as much to build and half as much to wear out and half as much to replace go with the panhard bar -- make it long and strong  willie buchta
willie-dpombatmir-buchta

Offline stratman59

  • Full Member
  • ***
  • Posts: 280
  • Age: 54
  • Location: Rocky Mount, North Carolina
Re: Watts linkage instead of panhard bar
« Reply #3 on: December 25, 2007, 04:19:48 PM »
what about the wishbone locator
http://chassisengineering.com/shopDetails.asp?CatId=10&SubCatId=69&ProductId=1620

with the anti roll bar
http://chassisengineering.com/shopDetails.asp?CatId=10&SubCatId=5&ProductId=908
thanks for any comments
not trying to steal anyones thread here just wanted to know yall thought
thanks
robbie
« Last Edit: December 25, 2007, 04:24:43 PM by stratman59 »

Offline willieworld

  • Hero Member
  • *****
  • Posts: 1818
  • Age: 75
  • Location: 921 chicago ave modesto ca. 95351
Re: Watts linkage instead of panhard bar
« Reply #4 on: December 25, 2007, 04:28:05 PM »
we tried them on the drag race cars --and they worked good --but then we were running with 2 flat tires   willie buchta-

they seemed like they had to much slop--and the way they are set up they wouldnt last long in the salt or durt  keep it simple you will have to many other things to worry about ---we always used the one from the chassisworks 
« Last Edit: December 25, 2007, 04:30:16 PM by willieworld »
willie-dpombatmir-buchta

Offline RidgeRunner

  • Sr. Member
  • ****
  • Posts: 822
  • Location: Ashfield, in the Territories of Western Massachusetts
Re: Watts linkage instead of panhard bar
« Reply #5 on: December 25, 2007, 04:32:13 PM »
     Don't overlook the wishbone option.  Buddy and I are building a lakester, were going to go with Watts then space got tight, considered panhard but it was going to have to be short, currently working up a wishbone.

                         Ed Purinton

Offline stratman59

  • Full Member
  • ***
  • Posts: 280
  • Age: 54
  • Location: Rocky Mount, North Carolina
Re: Watts linkage instead of panhard bar
« Reply #6 on: December 25, 2007, 05:17:50 PM »
i was thinking of going with the wishbone and 4 link in my studebaker because i think it will stay hooked better in high gear just my .02
robbie

Offline Bob Drury

  • Hero Member
  • *****
  • Posts: 2589
  • Age: 73
  • Location: Vancouver,Wa.
Re: Watts linkage instead of panhard bar
« Reply #7 on: December 25, 2007, 08:01:47 PM »
Stratman, you are asking for trouble.  If the car was glued on a rail then the wishbone locator is fine, but if you are sliding sideways at 200 mph, you are asking the heim joints and their brackets to work in ways for which they are not designed.  Leave the drag race Subaru on the drag race car and do it right.  Ask the salesman at Chassis Engineering if they would put the track locator on a roundy round car.  Your Studebaker is going to weigh a minimum of 3500#.  Either a panhard or a watts linkage put the heims in the plane on which they were designed to work............Bob       
 p.s., I think the wishbone locator would work fine on a lighter vehicle (as in m/c streamliner ) or a vehicle to slow to spin....lol)
Bob Drury

Offline stratman59

  • Full Member
  • ***
  • Posts: 280
  • Age: 54
  • Location: Rocky Mount, North Carolina
Re: Watts linkage instead of panhard bar
« Reply #8 on: December 25, 2007, 08:44:58 PM »
thanks bob for bring that to my attention. the salesman at chassis engineering said nothing about it when we but it does make alot of sense. do you think the panard bar with four link will be ok.
robbie

Offline 1977MGBV8

  • New folks
  • Posts: 14
Re: Watts linkage instead of panhard bar
« Reply #9 on: December 25, 2007, 09:44:37 PM »
It seems like there has been no ill effects wittnessed by using only a panhard bar.


I also have concerns about having the spherical rod-ends/heim joints loaded in an axial manner (forces applied to the bearing axis).  I don't pretend to know a lot about salt flat racing but my experience as an mechanical engineer tells me this could be a problem based on some info I have seen.  There is a limit to the axial performance of these joints generally, the is a rule of thumb I have seen applied of a reduction factor of at least 10 in difference between radial and axial load capabilities,  Ultimately, (in a slide as posted earlier) you are loading a joint that was not maximized for axial loads) that could be generated in a slide.  But it could be calculated to see how much margin there is.  But when doing so there is a combined load of twist and axial loads on the joint.

 


Offline jl222

  • Hero Member
  • *****
  • Posts: 2778
  • Location: Clovis calif.
Re: Watts linkage instead of panhard bar
« Reply #10 on: December 25, 2007, 10:20:23 PM »

     Stratman59

   We run a 4link with panhard bar ''Alston chassis'' no problems hooking up in any gear except low gear,still will not blow tires away except at slowest speeds.No problems in other gears,or high gear over 288 mph.

       Good luck  JL222
k


Offline Peter Jack

  • Hero Member
  • *****
  • Posts: 3717
  • Age: 76
  • Location: Calgary, Alberta
Re: Watts linkage instead of panhard bar
« Reply #11 on: December 25, 2007, 10:52:47 PM »
I've used the wishbone type successfully in other applications. Don't use a rod end for the single joint. Use a spherical joint, which is the joint they use in a rod end, and mount it horizontally in a machined socket. Just be sure you have the mounts built to give it adequate travel. The only other thing to be aware of with this set-up is that it gives a very low roll center which helps to keep the rear end stuck, a good thing.

Pete

Offline Rex Schimmer

  • Hero Member
  • *****
  • Posts: 2433
  • Age: 77
  • Location: Fulton, CA
  • Only time and money prevent completion!
Re: Watts linkage instead of panhard bar
« Reply #12 on: December 26, 2007, 01:04:24 PM »
I agree with Pete, turn the joint side ways to take the load and the other trick is to use a BIG rod end, 3/4 inch minumum and buy a premimum part, not the $10 ones that work for steering shaft supports. I use a "wish bone style locator on my streer roadster and the rod end is a 3/4 inch, aircraft quality piece that I paid about $75 for a number of  years ago. (I never throw anything away!)  Remember where ever the rod end is mounted to your rear housing that is the roll center. So you can do it high or low. My preference is like Pete's, low.

Rex
Rex

Not much matters and the rest doesn't matter at all.

Offline interested bystander

  • Sr. Member
  • ****
  • Posts: 990
  • Location: so cal
Re: Watts linkage instead of panhard bar
« Reply #13 on: December 26, 2007, 06:38:16 PM »
The lower triangle is probably the best approach although a Watt's linkage could offer more roll-center adjustability- be sure to either have it in phase with the other links to avoid "hinge bind" or if it's built with a slip joint that thing needs to be Seriously  STOUT and kept well-greased! 7/8 ball joints, NMB quality, would be my choice (take out a bank loan) The off road industry has manufactured housings for them that allow the part to be welded into your triangulated structure. G&J Aircraft Ontario, Ca should have them.

I'm not challenging the merits of the low roll center, but am interested in the it's why's and wherefore's as to its advantage on a basic straight line, low accelerating machine.
5 mph in pit area (clothed)

Offline GH

  • Sr. Member
  • ****
  • Posts: 843
  • Age: 78
  • Location: Springfield, Missouri
Re: Watts linkage instead of panhard bar
« Reply #14 on: December 27, 2007, 09:40:50 AM »
When I built my car, I made a panhard bar using heim (sp) joints, it had too much slop, you could rock the car left and right. I replaced it with a panhard bar using tierod ends with grease zerks in them, works much better.