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Old 12-25-2006, 08:39 PM   #736
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whats the point of a panhard bar? just put a little more triangulation in your links and there is no need.

edit- two links, both for rock crawlers but they are the ones that prodominantly use 4-link

http://www.rccrawler.com/forum/showthread.php?t=2169
http://www.4wheeloffroad.com/techart...ension_part_2/
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Old 12-25-2006, 08:51 PM   #737
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The point of the Panhard bar is to better control side to side movement of the axle. Better cornering results. Ford had a similar arrangement of highly angled upper links on the mustang for many years and they finally have seen the light and added a Panhard bar or its equivalent to the new mustang.


In tinkering with the suspension like it is now I have learned a couple of things. The angled links do resist side to side movement of the rear axle but it is a mushy feeling resistance. More angle reduces the mushiness but does not eliminate it. A Panhard bar with a sufficiently rigid fixed mount will reduce side to side movement and resultant cornering imprecision to a very small amount. You can see some space between the lower pod plate and the cars left side rear tire. I plan to sneek a frame rail into this space.

There is also an odd tendency for the rear pod to roll opposite to the way a normal car rolls with the upper links highly angled. The roll center must be very high. You can feel this when you push the pod sideways while you hold the car in your hands.

Putting more angle into the links would also result in the need to reinforce the center part of the car in some manner in addition to the front bottom link area. This way I think I can get away with the stock very light knife and just reinforce its support which will also reinforce the area where the bottom link attaches. I would not have put any angle on the top links but I needed a little more space to get the spur gear off without dissasembling too much of the car.

edit: A panhard bar will let me adjust the real roll center as well as letting me have a low roll center. I think this is important on a road car on asphalt.

Anyway I am going to try a Panhard bar. Thanks for the links. I notice some of the pics are down now.

Last edited by John Stranahan; 12-25-2006 at 09:14 PM.
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Old 12-25-2006, 09:02 PM   #738
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My initial thought when I first saw your panhard rod and saw that it wasn't adjustable I was surprised as any race car that runs a panhard rod uses an adjustable one. Then I realised that height adjustment is completely different on a pan car to a 1:1 car and the rear pod is not changing height to the chassis.

I'm an auto technician by trade and I've recently moved to doing wheel alignement and suspension work so it's interesting to see how you're doing this.
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Old 12-25-2006, 09:09 PM   #739
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Thanks. I appreciate the discussion. It lets me see things more clearly as well. I will be able to shim both sides of the Panhard bar up from its lowest position. I am able to adjust the height of the rear pod by raising and lowering the axle in the pod. Generally I keep it at ride height and you are right it will not drop much. For this reason I have put pan head screws under it to make a stronger bottom plate. Boomer knows about the weak hole.

edit: New Mustang Rear End with Panhard bar.

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Old 12-26-2006, 01:52 AM   #740
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Four Link Continued, Panhard Bar
The location of the Panhard bar has been more or less finalized. I plan to use this hollow Aluminum push rod to extend the frame back to support the fixed end. Trials on the table top seem satisfactory. The system is quite a bit stiffer laterally than with angled links. This aluminum extension will not be the best material to take a hard crash. It does flex, though, with lots of force and may actually survive a crash. The tube will sit in a U shaped plastic clamp and the forward end will be screwed into a bulkhead that will reinforce the frame on the sides. The right hand end of the Panhard bar is adjustable to change roll center or to compensate for ride height. The left side can be shimmed to adjust. It is supposed to be level at normal ride height. The roll center is where this Panhard bar crosses the center line of the car. There seems to be enough clearance on the parts for full left and right roll.
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Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-four-link-panhard-bar-resized.jpg  

Last edited by John Stranahan; 12-26-2006 at 02:16 AM.
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Old 12-26-2006, 04:36 AM   #741
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Quote:
Originally Posted by John Stranahan
Merry Christmas to all.

Four Link Rear Suspension with Panhard Bar Continued

Here is a pic of the new custom pod plates. The upper links will be angled slightly for convenience in changing the spur gear. Shocks and springs are on order. It will be a few days.

Mathijs-So the reason I donít just post the rollouts is that it only gives you part of the story. A guy needs to know what spur to buy what pinion is available. Is the spur too big to fit on the car. Now I am still wondering how you got that 25 mm/rev gear on your car. Did you find a source for a 16 steel 64 pitch pinion?
I have a full set of 64 pitch Corally pinions. I have to check but I believe the smallest was a17T.
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Old 12-26-2006, 08:54 PM   #742
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Four Link Continued, Shock Towers
Here is a pick of the new shock towers. There will be a 1/4 inch rail ouboard that they will be attached to at the bottom. I have all the details worked out now. A couple of small lower shock mounts to make and also the frame rails. Will be finished in a couple of days maybe. Losi style rear body posts will be mounted far back on the shock towers to better support the wing.

Now in case you want to make a part out of this graphite I'll tell you that I am just cutting this stuff out with the Dremel narrow cutoff wheel and then sanding it a bit. I marked the holes in the top and bottom plates using stock parts and a small prick punch or transfer punch. I covered the graphite sheet with masking tape and drew a pattern on it with help of a square. I used the lines as my guide to cut it by hand.

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Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-four-link-shock-towers-001-resized.jpg  

Last edited by John Stranahan; 12-26-2006 at 09:15 PM.
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Old 12-27-2006, 10:56 AM   #743
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Sweet it will look good with the Strut front suspension I am working on. with a lower arm only and a shock in the front!
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Old 12-27-2006, 09:01 PM   #744
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Why didn't you try the pan hard bar here ? Chassis and Pod?
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Last edited by Marty Peterson; 08-03-2008 at 01:40 PM.
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Old 12-27-2006, 09:26 PM   #745
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Marty-Thanks for the posts and the interest.

The main reason not to put the Panhard bar in that place is that the space there is an illusion. With certain gear combinations the motor will intrude into the space you have shown. The link cannot be quite as long which will cause more change in turning left to turning right. Also my rear battery spacer will probably not be there. This will allow me to move my Lipos as far back as possible for the best rear traction. I have an alternate battery support built into my frame rails. I did think about putting the Panhard bar there and maybe you could squeeze one in there. It is going to take serious abuse in a side crash into the boards so the link itself needs to be fairly stout. The angled upper links will help in this respect by lowering forces on the Panhard bar. I chose the T-max push rod for this part so that it would take the abuse of a crash. On my car, the part that goes back will not be a rod. It will be an extension of the frame approximated 1/4 by .3 inch in cross section. (Stout). I'll cut them out tomorrow and put up a pic. Note also the Panhard bar should be adjustable up and down. I don't know the perfect spot up and down yet, I will need a test.

According to Herb Adams in Chassis Engineering (and Mathjis) You can't put too much of your weight on the back on a two wheel drive rear drive car. Now that I have front shocks the car is much more stable at high speed on the straight. I can push things back a little.
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Last edited by John Stranahan; 12-27-2006 at 09:44 PM.
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Old 12-27-2006, 10:22 PM   #746
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I was thinking something similar to what Marty posted except maybe a little more like this, although I'd try to extend the front brace back to give it less of an angle.


I'm not sure if this picture will upload, and my artist skills are really bad.
Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-pantoura4link2.jpg  
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Old 12-27-2006, 10:51 PM   #747
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GreaseMonkey- Thanks for the sketch. The roll center is the place where the Panhard Bar crosses the center line of the car. A bar could be placed like your diagram more perpendicular to the center line of the car. The roll center would be way up at the top of the motor. I think the best roll center is going to be near the ground so the Panhard bar has to be low. The rear of the pod does not go down when you hit a bump. This lets me put the bar so that some parts are even below the pod bottom plate. I'll see more when I test it. The bar needs to be able to have adjustment from very low to maybe 1/4 inch up off the chassis.
This pretty much rules out both of those new suggested position. Raising the bar will hit the motor with Marty's suggestion. Lowering the bar will hit the motor with your suggestion.
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Old 12-27-2006, 11:18 PM   #748
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John your right it would hit the motor in front and the way you are going to do it with the Front Chassis extending back past the rear pod should work out for you. (this is the Wide Car right) I would not be able to make this work with the 190mm Car But I will sure be looking to try it on the wide car!

Here is something I was looking at no need for a pan hard bar but it would not work with your setup but it might with my 190mm
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Last edited by Marty Peterson; 08-03-2008 at 01:40 PM.
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Old 12-27-2006, 11:26 PM   #749
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Marty-yes my mod is on a wide car and would not fit as is on a narrow car.

Your last schematic is unclear to me. Would this be an independent rear suspension. If so it would not fit in a pancar class, but may be a good way to build the car. This would be a belt drive then?
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Old 12-27-2006, 11:44 PM   #750
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John I am making a belt car with a independent rear suspension as well But this is off of a 1/4 scale Car.
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eBay item number: 200947192161,200947193175,200947187493

Last edited by Marty Peterson; 08-03-2008 at 01:40 PM.
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