R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Reply
 
Thread Tools Search this Thread
Old 02-05-2009, 08:59 PM   #586
Tech Apprentice
 
Join Date: Oct 2005
Posts: 64
Default Question About 3 Link

First let me say your car look great, I have one question about the conversion to the rear shock set up. Why did you get rid of the center shock and go with a solid link???...

Dave D
__________________
RACING IS A LIFE SENTENCE WITH NO CHANCE OF PAROLE!!!...
"WINNING IS NOT EVERY THING IT IS THE ONLY THING" VINCE LOMBARDI
DANGEROUS DAVE
STSDAVE is offline   Reply With Quote
Old 02-05-2009, 10:25 PM   #587
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

STS Dave-Thanks. Let me answer your question directly first. Three pan car shocks and springs are replaced by two. Yes it looks like the center shock is replaced by a solid link, but the center shocks function is replaced by two shocks that are much closer and more direct with the wheel bump. The top/side shocks are now unecessary and are eliminated. Their action is taken up by the side shocks like in most cars. The pod motion side to side is now restricted by a Panhard bar just in front of the pod instead of a center hinge (T-plate or pivot). There is no center pivot on this car. If you unhook the shocks you will find this suspension extremely free moving compared to the hinged cars. The inspiration for this design is the Trans Am race Car (Mustang , Corvette, Camarro bodies) which have solid rear axles and used to run the Champ Car road courses before the Champ Cars in the not too distant past. The key is long rugged links, and a Panhard bar or Watts link to control side to side motion.
The Nascar Nextell cup rear suspension is actually more antique than this; it is a two long curved inward links extending forward from the axle solidly attached to the rear axle housing and pivoting at the front, from a 1957 Chevy Pickup, It adds a Panhard (or Track Bar).


My cars suspension is called a 3-link with Panhard bar rear suspension. The traditional suspension puts a hinge in the middle of the chassis. This is either a T-plate or a center pivot ball. I have neither. In my experiments through the bumps outdoors the performance goes like this, last place T-plate, It sounds better (is quiter), but the radar on the straight tells the tale. There is a lot of tire bounce (patter sound) and tire spin. Next a center pivot link car. Next a 3-link with Panhard bar. The numbers go like this 47, 49, 53 mph reached at the end of the straight. The improvement of the 3-link is evident coming out of every corner so improvement on the straight is not its only benefit. Lap times are improved.

So what does the three link do better. It returns the wheel that has gone up from an uneven bump faster to ground. The shock and spring acts much more directly on one wheel. The 3-link also loads the rear wheels on power faster and more than the hinged cars. It has better antisquat. I have determined this by feel and it is also evident in antisquat calculations of each suspension. Much of my experimentation was done on the Pantoura thread. Now I just hope to see a production version some day for World GT or Pro 10(wide pan). Mine is just a prototype free to the public.

This is the first model, I have made, that you can almost just bolt together. You do have to drill some holes.

It is my third pan car 3-link rear design in a series.

Pics
I Wide Custom Pan Car
Panhard Bar in Rear (moved to front of motor recently). Solid left side frame rail to Panhard bar. This car has a dual A-arm custom front. This is my fastest pan.
The two battery experiment was not succesful as the Mamba Max speed control was not up to the task even with a Novak 6.5 R. How about some Enduro. 10000 mA-h will fit.

II 200 mm car modified to 4 cell for the oval.
Front of Motor Panhard bar, Rear of Pod shocks shown on this pic and the next. MLP had a similarly designed road car partially CADed up at one time.

III Latest 200 mm 3-link. Almost a bolt together setup. The shock placement here makes the car more suitable to high traction and carpet. Rear Roll control is enhanced (stiffened) by wide shock placement. We should have high traction asphalt soon. Both ends of a short Panhard bar are just visible under the back of the Hyperdrive red upright.
John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-novak-6.5-r-4s2p.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-3-link-top-view.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-3-link-back-view.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-new-3-link-pan-road-car-005.jpg  

Last edited by John Stranahan; 02-05-2009 at 10:48 PM.
John Stranahan is offline   Reply With Quote
Old 02-06-2009, 01:27 AM   #588
Tech Adept
 
Join Date: Jan 2007
Location: Switzerland
Posts: 131
Default

Hey John

I didn't read the hole Battle Axe an Pantoura thread. Have you ever tried to combine the panhard bar suspension with the motor behind the differential?? I think this would add some traction through the motor torque. Also a very narrow chassis would be possible.
Der Dicke is offline   Reply With Quote
Old 02-06-2009, 07:12 AM   #589
Tech Apprentice
 
Join Date: Oct 2005
Posts: 64
Default

I missed the panhard bar when I looked at the first pictures of your car, now that I see that it is much clearer to see how it will work. I like your design, and missed if you are running on carpet or out side on pavement. I would like to try this for carpet racing just because it has a COOL FACTOR !!!...

Dave D
__________________
RACING IS A LIFE SENTENCE WITH NO CHANCE OF PAROLE!!!...
"WINNING IS NOT EVERY THING IT IS THE ONLY THING" VINCE LOMBARDI
DANGEROUS DAVE
STSDAVE is offline   Reply With Quote
Old 02-06-2009, 11:35 AM   #590
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Der Dickey-I have not tried putting the motor behind the axle. I have one small experiment that suggest the car would be too loose. I placed the speed control behind the rear axle and the car became very loose; it oversteered just from moving that weight back. I quickly moved the speed control back to the chassis.
The motor is aranged now to lift the front wheels on power. This gives the maximum rear weight transfer and forward traction on power. With the motor to the rear of the pod the rear of the pod would tend to lift but with good rigid links this would not drive the rear wheels down, it might even transfer weight away from the rear to the front wheels.

Dave-Give it a try. This latest suspension should work well on carpet. I have only tested on asphalt but at times it is very high grip, traction rolling the 1/12 scales.

This is what I made the lower shock mount from. Durro Collars
http://www3.towerhobbies.com/cgi-bin...?&I=LXD833&P=7



Get this high speed steel countersink, 82 degree, with an .082 tip to start the hole and then to Countersink Bottom of Chassis
http://www.mcmaster.com/#27535a13/=i1ec0

Get this Drill .110 inch, To Through Drill Chassis to clear a 4-40 screw.
http://www.mcmaster.com/#28765a881/=i1j92

These last two tools modify that Durro Collar into a lower shock mount.
metric tap 2.5 x .45 mm, plug tap
http://www.mcmaster.com/#8305a11/=i624l

drill for 2.5mm x .45 mm hole use a (2.05mm) or .081 inch, #46 drill
http://www.mcmaster.com/#28765a826/=i63fa

John

Last edited by John Stranahan; 02-28-2009 at 09:52 AM.
John Stranahan is offline   Reply With Quote
Old 02-06-2009, 03:58 PM   #591
Tech Initiate
 
Join Date: Jan 2009
Location: Netherlands
Posts: 29
Default

(Late, late reply. )

Okay, thanks. Just need to find a shop that sells them and accepts Paypal and has decent overseas shipping rates.
__________________
Pancars: Trinity Evolution10 mk.II, Trinity Switch Blade 2, Trinity Street Spec, Tamiya Group C
Thomas_H is offline   Reply With Quote
Old 02-06-2009, 05:29 PM   #592
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Difficult criterion if you use Paypal only.

Track Report Concrete Oval

I changed my sugar Recipe. I also changed to a part of the parking lot which has no through traffic. The dead end. I put on 12 lbs of sugar in 5 gallons of water. Traction was just super. Better than the asphalt. I can fine tune the sugar. Probably 10 lbs will do it. The secret is too have enough sugar and use enough water that it leaves a light stain on the concrete. If it dries concrete white you are not done yet. I am just thrilled. Oval testing can continue during our construction.

I ran the Superior spectre Oval car. It turned in like a son of bitch. Accelerated like a rocket. Perfect. Jeff and I both ran the oval. We thought the oval could use about 2 more feet of width on one side and it could be longer. I have about 4 feet more length of concrete that I could use. Woo Hoo. More test to come. Hope to have a group on it next Friday or Sunday. Not a single setup change was needed. I was using my typical for asphalt tires which are pink LF, purple RF, XXPink/Purple rears.
John

Last edited by John Stranahan; 02-09-2009 at 09:03 AM.
John Stranahan is offline   Reply With Quote
Old 02-06-2009, 05:59 PM   #593
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Oops wrong thread. Moved to the Gulf Coast Racing thread
Re: track progress, Possible Electric classes at Mikes.
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-pan-road-car-toyota-body-resized-006.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-peugeot-905-b-908-colors-006.jpg  

Last edited by John Stranahan; 02-09-2009 at 09:13 AM.
John Stranahan is offline   Reply With Quote
Old 02-08-2009, 03:20 AM   #594
Tech Regular
 
s13evo's Avatar
 
Join Date: Sep 2007
Posts: 361
Trader Rating: 8 (100%+)
Default

Hey john, would i achieve a little better rear end grip with the GENX10
235mm extention kit compared to its stock setup on outdoor asphalt??

thanks in advance.
s13evo is offline   Reply With Quote
Old 02-08-2009, 07:36 AM   #595
Tech Apprentice
 
rsperson's Avatar
 
Join Date: Nov 2002
Posts: 62
Default Fantastic looking 3 link

John. I love the look and thought and testing that has gone into this setup.

Its probably all through the thread in bits and pieces - BUT.

could you post a parts list for the whole thing?

I would convert my CRC to this in a heartbeat - If I was sure that I could get all the parts.

It just makes too much sense.

ps: I've been thinking about how to do just this - only on paper - for about 20 years and have always gotten to a dead end.
Thanks for showing the way.
rsperson is offline   Reply With Quote
Old 02-08-2009, 09:49 AM   #596
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

s13evo-yes. More cornering grip and more forward grip.
rsperson- Here it is.
Parts List for 3-link with Panhard Bar rear end
with transverse shock tower. I have had this rear end on a T-plate car as well as a Gen X 10. On a T-plate car the Darkside I-force shock tower will also work.

Axial AXA1102 Reverse Cone washer 3mm hole for flat head screw. (5) $5.99
Axial AXA1360 7 x 10 mm standoff Red Aluminum Threaded 3mm $4.79
Hyperdrive HD7326 Pro 3 Solid Cross Brace $28.00
Hyperdrive HD7320 Pro 3 Shock and Body Mounts $13.00
CRC 1403 Red Anodized Short Standoffs, 4-40 thread $4.00

GFR 1018R Red Aluminum Base, Body Post, Screw type $29.00

Shocks for the Transverse Shock Tower 3-link
ASC 21082 Ball studs for Associated RC18T $8.59
Associated 21216 RC 18T front shocks for Transverse Shock Tower Pan $18.39
Duratrax DTXC4212 Locknut 2.5 mm $3.59
Associated 4475 vcs side spring Black, Cut to length for 3-link, Cut end up. $1.90
Associated 5435 50 weight shock, silicone fluid $3.39
Dubro139 Duro collar, 1/8 inch, 4-40 set screw, for lower shock mount (4) $1.70

CRC 4246 Lowered left pod plate $17.00
CRC 4247 Lowered left motor plate $16.00
CRC 1365 Graphite top plate CRC cars $9.99
CRC 1366 Graphite Pantoura Bottom Plate V3 $13.50
Traxxas 5539X Jato Links set of 6 $28.99
Duratrax3737 Red Turnbuckle, 39 mm, Short for Panhard Bar $5.79
Associated 7260 thin 4-40 nuts $1.90

This is about $135 so far without dress up items nor shock oil and spring which you might have on hand, but there are enough links and ballstuds for two cars.

This is the tooling needed to drill and countersink the chassis, and to thread the lower shock mount.

Get this countersink, 82 degree, to start the hole,.082 inch, and to Countersink Bottom of Chassis. Get 3 each of these tiny drills while you are at it.
http://www.mcmaster.com/#27535a13/=i1ec0

Get this Drill .110 inch, To Through Drill Chassis to clear a 4-40 screw.
http://www.mcmaster.com/#28765a881/=i1j92

These last two tools modify that Great Plains Collar into a lower shock mount and are also found in most hobby shops.
metric tap 2.5 x .45 mm, plug tap
http://www.mcmaster.com/#8305a11/=i624l

drill for 2.5mm x .45 mm hole use a (2.05mm) or .081 inch, #46 drill
http://www.mcmaster.com/#28765a826/=i63fa

Additional lower shock clearance on the side links is gained by using a thin hex nut on the side link rear pivot (or even cutting the top flange off the pivot ball if necessary).

John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-new-3-link-pan-road-car-002.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-new-3-link-pan-road-car-003.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-new-3-link-pan-road-car-005.jpg  

Last edited by John Stranahan; 02-09-2009 at 08:55 AM.
John Stranahan is offline   Reply With Quote
Old 02-08-2009, 09:08 PM   #597
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

3-link with Panhard bar rear end
The function of the shock tower is simple. It has to rigidly hold that pivot ball in place. For this setup the pivot ball needs to be 1.75 inches above the chassis and 2.5 inches out from the center of the car. You can trade one distance for the other a little.
My though now was to reduce cost a little, but probably at the expense of some tidiness and extra handwork.

Here is pic of an alternate shock tower. I have shown two previously, the darkside I-force model, and the Hyperdrive Model. This one is more CRC based and takes advantage of pieces already on the Gen X 10. We basically have to add another inch to the spring side plates. That center red aluminum shock mount/antenna mount may help. It has two sets of cross drilled holes. This bolts up stock to the side plate or the extended side plate using existing holes. Then you are left to go up another inch with aluminum titanium or graphite. Here is a piece of titanium shock tower posibly from an NTTC3 that I trimmed. You need cobalt drills to drill titanium. I am satisfied with the Hyperdrive parts except that they are a little heavy.

CRC1745 Antenna Shock Mount $9.99

I have not worked this CRC based rear 3-link to a complete working suspension. The baby shock tower may need to be moved forward to another existing hole on the side plate and then a trim of the side plate, or the bottom plate redrilled farther back for lower shock mounts.

John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-crc-center-shock-mount.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-crc-center-shock-mount-001.jpg  

Last edited by John Stranahan; 02-09-2009 at 08:54 AM.
John Stranahan is offline   Reply With Quote
Old 02-09-2009, 04:34 PM   #598
Tech Adept
 
Join Date: Apr 2003
Posts: 222
Trader Rating: 18 (100%+)
Default three link

john wont the panarod make the rearend swing left and right i have looked at this for sum time and the geometry just dont jive
__________________
Team Green Racing
LemonHead motorsports
TOP Racing
Doug Lemmons is offline   Reply With Quote
Old 02-09-2009, 04:41 PM   #599
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Doug-Yes a Panhard bar makes the pod move left and right a little as the suspension moves. A longer Panhard bar like in my earlier designs reduces this. A Panhard bar is also supposed to change the roll center a little as the axle goes up and down. My experiments with the long and then short Panhard bar show little difference in handling. All the benefits are still there. A high vs low Panhard bar shows little difference in handling. We really do not have control of the roll center with this panhard bar.

The suspension also moves very little. The laden or outboard size is depressed only a little with roll. The side to side changes are not noticed at all. Movements side to side here are probably only in the .01 inch range. This is the really about the best setup for a solid axle on full size cars, and, as it turns out, on our solid axle.
John

Last edited by John Stranahan; 02-09-2009 at 04:55 PM.
John Stranahan is offline   Reply With Quote
Old 02-09-2009, 04:42 PM   #600
Tech Adept
 
Rob Burns's Avatar
 
Join Date: Jul 2008
Location: Sydney
Posts: 176
Trader Rating: 4 (100%+)
Default

That's a normal characteristic of a panhard rod. Ideally he'd be better off with a watts link. Making room is the hard part.
__________________
www.RCOttawa.com
Rob Burns is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks John Stranahan Oval, Larger Scales and More 0 05-25-2008 11:48 AM
Electric 10th scale sell-off (T4 team, Sphere, Transponder, LiPo, Brushless...) floatch R/C Items: For Sale/Trade 27 03-14-2008 04:37 AM
Battle Brushless Sensorless Mamba Max : Trinity N80 VS CM 36 moumerico Electric Off-Road 3 04-12-2007 03:18 PM
Battle of the EPs (On or Off Road)! marzin Singapore R/C Racers 4 09-22-2005 09:27 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 01:40 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net