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MG MGB GT V8 Factory Originals Technical - help please with a panhard rod
|I am going to build a panhard rod for my '77 B with a 3.4 V6 ove the winter. Does anyone have a great idea for the project?|
|c l sorenson|
I built my own panhard rod and ancillary. The anchor to the rear axle is welded with a rose jointed to the rod and the anchor to the shell is also welded with Triumph polyurethane bush to the rod. At neutral position the rod is parallel to the rear axle. That work very well.
|http://www.mgbmga.com/index.html. Doug Jackson's site with his own version, which I've heard from all who've popped for the bucks, is an excellent piece of work|
|Check summitracing.com or jeg's. They have a universal panhard rod kit for about $90. Just a little welding required. I think its a Competition Engineering piece. Good stuff.|
Panhard rods are a big improvement to MGBs. There are several examples here:
My two cents worth: It's important the rod sets parallel to the ground. It's desireable the rod be as long as possible. All else considered, lower is better than higher. The connection to the body needs to be stiff. Although rubber or poly bushes would've worked, I found using spherical rod ends on my Panhard rod didn't harshen the ride noticeably. I recommend them for ease of installation (since they make rod length adjustable) and obviously for performance (since they make rod length constant.)
|Go to your local Wrecking yard, look at a Camaro or Firebird V8 or V6 These cars have the best engineer bar. These cars needed so their design is a bolt on.|
It really works and it's simple.
I have what I need now.
|c l sorenson|
|Bill- You mean that four foot long tapered thingie running from the axle forward????|
That would be the torque arm.
|The Camaro has a torque arm that is attached to the axle and the tail shaft of the transmission.|
The Panhard rod is attached to the body pan and the rear axle. This type of copnstruction is very strong for the stock-modified V8 engine well over 375 hp (I have one) No welding necessary, it's just a well design piece and light and simple.
Bill, I'm not comprehending what's special about a Camaro Panhard rod, or why it's especially relevant to MGB. I'm curious, but can you save me a trip to the junkyard? Here's a photo I found of the Camaro body bracket:
Does this bracket bolt on? Certainly you're not suggesting it'd bolt onto MG?
Or is it the rod that's special? All I can see is the stock Camaro rod is quite long and non-adjustable... (It'd probably need to be cut down and rewelded, no?) There are lots of aftermarket "upgrade" Panhard rods available for Camaro, including tubular rods, rods with spherical bearings instead of bushes, and rods with adjustable length via Heim joints... Is it the mounting at the axle end that's special? Maybe these rods connect to some clever feature of the Camaro axle, but I didn't find a photo of that end. Is it something that would work on MG or Ford axles?
|What I did suggest is to copy the design. Adjustable bars help adjust discrepancies between models.|
The bar should fit level to the ground, in the midle of the housing and not strains, meaning it should bolt right up. The Camaro is a good design and it was suggested to copy the design and build your own bar for your MGB. The picture that you have share is for a late model Camaro 98 up.Camaro.
To be more specific:
The F body GM cars use a long bar that is bolted to the body pan, the bar curves down, the end attaches to the bar, bar attaches to the differential via a plate which is welded to the axle. Ok now that plate that bolts to the axle can be bolted to the B spring pad. This makes the Panhard rod 100% bolt on. The Panhard rod then can be adjustable if you like or made to fit your created space.
To get a better picture of this design look at F body maunal such as Haynes etc.
The bar that bolts to the body pan in the F body, similar rod can be bolted in the B on the front of the trunk pan same as the GT, then fabricate a plate that can be bolted to the spring pad with a hole or stud to accomodate the Panhard rod.Measure the space and fabricate the Panhard rod.
Three things to consider.
1. the bar should be paralell to the ground.
2. It should be place in the midle of the axle.
3. The ends of the Panhard rod should be solid.
The lengh is not a problem in the B since the travel of the rear suspension is very litle, so the lengh of the Panhard rod should be at least half the axle shaft or longer, but not shorter than half.
I hope this helps to clear your thoughs about the Panhard rod.
I have seen some that are bolted to the corner of the trunk with some reinforsment, avoid this design, make it as long as posible for stiffness of the supporting bar.
I have not looked at the camaro, but have a question.. I like the idea of spring perch mount, like a tubular shock conversion....
You said the bar should be at least half the axle shaft.. Do you mean I could make the bar from the spring perch to the center of the Diff housing (~length of a axle shaft) and that would be fine?? I always though they sould be most of the length of the rear axle housing??? Also it dounds like having the bar parrallel and in plain with the axle shafts is best.. so mounted behind the axle then?? has anyone ever seen or made a curved/form fitted bar to clear obstacles?? This has been a good disccussion with lots of ideas popping into mind...
That is something I need to so this year when I do the 8.8 Ford swap, so now is the time to figure it out...
|The bar does not have to be straight, but a straight bar will be more rigid than a curved one so you will need to allow for flex by using a larger diameter or thicker wall tube for the bar. The end points should be level with each other with the vehicle normally loaded. The further apart the end points are, the less side movement is created as the axle moves up or down so longer is better. (a Watts link avoids this problem but requires more space and fabrication to implement)|
|Larry, the bar is best in the rear of the axle.|
A short bar is ok in the MGB due to the short travel of the B's axle. A longer bar is always better.
conduct your own test.
Place a long bar on the floor of the garage, draw a straigh line in the direction in which the bar will move. Now move one end of the bar the amount of travel of your axle. Now measure how much the rod is inside that line. this will determine how short your bar can be. t should move 0 or very litle. When not sure make it long, the lengh of the axle.
I sent some photos and I have a couple more if needed.
|Has anyone tried a "Y" link that mounts near the front spring hangers and at the center of the rear axle? This would do double duty both as a panhard rod and also act as a bit of an anti-tramp bar.|
|Yes, I have. Actually is a Lotus design. A bracket needs to be welded to the rear axle to accept a Hiem joint 3/4 or 5/8 shank with a 1/2" bolt hole. At front you will need build and weld perches to accept the hard bushings, prefered is to use solid alum bushings, this helps in locating the axle.|
Problem is that it hangs low, good is that it changes the roll center. This type of changes creates a domino effect. Needless to say, they are good changes.
|Moss Motors offered a "Y" bar for a year or so, about 10 years back, advertising it as a combination panhard rod & traction bars. It did not sell very well.|
As far as fabricating a panhard rod, unless you have good skills & a welder, I suggest you buy one from Doug Jackson. While not cheap, for most of us, our time is limited, & designing & constructing one was for me, a bit like reinventing the wheel.
Doug's bar was custom made to fit my Ford 8" rear at no additional cost. Fit was perfect, adjustment took only about 10 minutes, & worked perfectly with the tube shocks & fiberglass spring mounts.
Panhard rod & heavy duty torque arm installed on a Mustang:
Panhard rod relocated to allow for dual 3" exhaust on a Camaro:
Aftermarket torque arm on a Camaro:
2005 Mustang w/3-link, Panhard rod, & anti-sway bar:
More, just add MGB body! :)
Bit long don'tcha think?
|Okay, Jim, just add MGB body + shorter driveshaft. :)|
|Most of the production cars such as Camaros, Mustangs, Volvos have rubber or poly bushings at the ends of their panhard rods. It seems like Doug Jackson and the folks that fabricate their own use adjustable heim joints on both ends with jam nuts. Does this cause the noise inside the differential to reverberate into the passenger compartment? I know there is a lot of outside noise anyway, but would this cause a drone like when part of the exhaust system is rubbing on the frame of car? I'd appreciate your thoughts on this.|
|I don't know about the noise transmission, but I prefer to use urethane bushings on street cars and save the heim joints for all out race cars. The urethane takes a bit of the harshness out of the ride while still maintaining good location.|
Larry asked: "Do you mean I could make the bar from the spring perch to the center of the Diff housing (~length of a axle shaft) and that would be fine??" The answer is NO! A bar mounted as described wouldn't be a Panhard rod, and furthermore wouldn't control lateral body movement relative to the rear axle and tires. The described bar would be redundant with the axle housing itself.
While an interesting compromise, I feel compelled to point out that a bar mounted from spring perch to body would be somewhat less effective than one mounted directly to the axle because there's a rubber pad between axle and spring perch. Combine that with rubber bushings on the rod and a body mount to sheetmetal (that flexes) and I bet you could rather easily make a totally ineffective Panhard rod while significantly increasing unsprung weight.
Whether you're gonna buy a rod or make one (which is a relatively simple and rewarding project), I recommend the book "How to Make Your Car Handle" by Fred Puhn. It's an entry level text that does an excellent job of describing practical suspension mods and tuning, plus theory.
I do have a "drone" noise I have not been able to find, so I removed the panhard rod - it is a Doug Jackson product- & found no reduction in noise drone. It goes back on tomorrow.
"a bar mounted from spring perch to body would be somewhat less effective than one mounted directly to the axle because there's a rubber pad between axle and spring perch"
It would depend if it was mounted on the top of the botton of the spring perch. Common sense would tell you to mount it using the four bolts on the perch away from the pad. Many SUB's (Japanese) use a short panhard bar. My Rod a 32 Ford, uses a short panhard rod on top of the axle. Many street rod kits come that way.
|for michel, aix en provence france |
I'm more inteested in your rear disc brake set up could you give me more info.? Your panhard rod set up
looks very well done congrats.
|Thank you Bob. For install the rear disks brakes I use the original flange machined with four tapped holes for bolting a bell machined in aircraft ally. The rotors are Brembo for front MGB machined for adapt to the bell. To the rear axle a new bearings retainer are built for holding the calipers. I use pedal box with balance bar and hydraulic handbrake.|
To the front I use 295mm vented AP racing rotor with four pots AP racing calipers. Good braking.
Sorry for my vocabulary.
|I must Michel, that I hope that you get the car on the road. It looks like a fine piece of craftmanship. /|
I installed the Doug Jackson Panhard rod and am very pleased with the results. That said, the noise transmission is notable. In fairness, I should say that the rear end was noisy to begin with, there are performance bushings all over, and being a GT with the rear deck removed, the resonation effect is increased. A roadster may not have the same level of noise. If I were going to start using the GT more for basic transportation again, I would consider dampened heim joints.
|To nourish my Holley carb, I fit an Holley electric fuel pump (blue). She make more noise than all the remainder.|
I have big problems for registration in france. I use the car for track day, essentially.
Chris, a question, what the Republic of Texas?
|Michel, do you you do your own tig welding? it's very nice work. Republic of Texas is kind of local joke. After the battle of the Alamo, Texas became a Republic unto itself, free and independent of France, Spain, and the U.S.. Many locals act like things are and should be the way they were in the 1840's. After living in San Antonio for two years now, I'm still tickled by the Texas Attitude. Comprenez-vous? Vous effectuez le beau travail!|
Thank you for your congratulations. Yes, I understand all. The ally parts are welded by a friend of mine. For the time I weld only the steel. Building the cars is my hobby, I try to do it well. Now, I am in process to build a 1924cc engine (fuel injection, ignition distributorless) for my BGT, daily use.
|Jim and Dean|
Thanks for addressing the noise issue. Seems like I should be able to drown out whatever extra noise by turning up the volume on my radio that is wired into headrest speakers on my Fiero seats.
I do have another concern. After I switched to 195/60 series tires a couple of years ago I did have some rub inside my left rear fender. Rather than putting on a panhard rod I installed the triagulation kit the MG Owners Club sells. For those not familiar with it, it consists of a piece of mild steel about 1 1/4" wide by 11 1/4" long and 3/8" thick. It is attached to the front spring ahead of the the axel and on the axel itself probably about 9 or 10 inches inboard from the axel flange. That solved the problem of fender rub on hard cornering, but since then I've sheared off the center bolt the holds the leaf springs in place on the right side. I think I've replaced it three times and this never happened before I put on the triagulation kit. Maybe the triagulation kit keeps the springs from operating properly? Last summer I was in a small wreck the pretty much demolished the left rear quarter panel. The center bolt on the left side sheared off then, too, but probably because I was skidding across I25. I had the body shop roll the inside of both quarters so now I have more clearance and maybe rub won't be a problem. I still think a panhard rod is a good idea to improve handling as well as adding torque arms to control spring wrap up. My friend that recommended the triagulation kit is using it on his 4 cylinder B and likes it.
|i may make a complete fool out of myself here but i'll ask anyway, what does a panhard rod do exactly? looks to me like it just keeps the hole back end a bit more rigid? |
|J P Connor|
Copied from another source...not my work! -
A Panhard rod is a component of a car suspension system that provides lateral location of the axle. Originally invented by the Panhard automobile company of France in the early twentieth century, this device has been widely used ever since.
While the purpose of the rear suspension of an automobile is to allow the wheels to move vertically with respect to the body, it is undesirable to allow them to move forward and backwards, or from side to side. It is this latter movement that the Panhard rod is designed to prevent. It is a simple device, consisting of a rigid bar running sideways parallel to the rear axle, connecting one end of the axle to the car body or chassis on the opposite side of the vehicle. The bar is attached on either end with pivots that permit it to swivel upwards and downwards only, so that the axle is in turn allowed to move in the vertical plane only. The advantage of the Panhard rod is its simplicity. Its major disadvantage is that the axle must necessarily move in an arc, relative to the body, with the radius equal to the length of the Panhard rod. If the rod is too short, there will be excessive sideways movement between the axle and the body at the ends of the spring travel; therefore the Panhard rod is less desirable on smaller cars than larger
|oh right, seems simple enough. so can you have a two directionsl panhard rod? one parrallel with the axel and one 90 degrees to that one to stop forwards and backwards motion? would that make it a bit too rigid?|
|J P Connor|
|A rod 90 degrees to the axle is not considered a panhard rod- these trailing arms would cause some deflection in the panhard that needs to be addressed with bushing compliance in a rubber or polymer bush, or a rotary motion as available in a sherical rod end.|
There are trailing arms kits available- they are usually referd to as traction aids, as they prevent leaf spring windup in acceleration and deceleration, ruducing wheel hop.
Probably the most common configuration of what you suggest in the US is what's known as 'truck arms'- this was a 3 link suspension with coils used in some Chevrolet light trucks. There are 2 trailing arms, converging toward the front, that are solidly fixed to the rear axle- no rotation of the arms with resepoct to the axle is permitted. This suspension has been the standard for American Silloute Sedan Racing (NASCAR) cars since forever- Not particularly sophisticated, but well developed and effective on ovals.
Not mentioned yet is that a panhard also controls roll center height- even of leaf spung cars. Depending on where the panhard is located (above or below the leaf spring mounting pads), it can modify roll couple distribution from front to rear, modifying handling
|Wouldn't the change in roll center depend on the mount location to the body either above or below the spring attachment points?|
A Watts link is what is used when lateral movement of the axle is not acceptable. A bit more complex, but it uses an arm (usually vertical) with a center pivot which is attached to the axle, then a link rod from each end of the arm to attachment points on the body, one high and one low. The rods are parallel. When the axle moves up and down the arm rotates a bit but the axle can't move sideways.
Michel, where in the world did you get those radiator hoses? Those are sharp!
On the subject of radiator hoses, Autozone #L182 and L59 are good hoses for the BOP conversion. Best match I've found yet.
Where? In Wales to Demon Tweeks www.demon-tweeks.co.uk
The trademark is SAMCO, www.samcosport.com a huge range of silicon hoses.
The roll center is relocated from the spring mount pads to the center of the panhard rod. If the rod is located below the spring mount line, the roll center is lower. If above the line, the roll center is higher.
A watts link pivot can also be mounted to the body, if a lower RC is than the axle centerline is desired
There are other methods if locating the rear and adjusting roll center height. Jacobs Ladders, Woblinks, and Mumford links spring quickly to mind. The mumford is particularly interesting- Mallock used it on his U2's to get rear roll center below the ground line. On the west coast, there is a Mallock that is a class legal Formula Ford, that runs VERY competitively w/ a front engine/live rear axle against the rear engine/Webster and Hewland transaxles common in the class.
|Yes Greg I seem to recall that now. But I do not remember what configuration is used in the Mumford.|
Any more info on those hose numbers you listed? Make, model, year, appliation, etc?
|No, I just went to Autozone and rummaged through their selection and those are the ones I came up with. They match up really well for me. I've been looking at hoses for better than 20 years now off and on. Anyway those are their stock numbers. If you have to go somewhere else see if they can cross reference them for you.|
Mumford is a 5 link transverse locator
Consists of two pivotng links that are frame mounted, and three connecting links. One pivot link is a 180 degree bellcrank with pivot in the center, the second is a 90 degree bellcrank. two of the connecting links are attached to the axle near the hubs, and are angled up and attached to the bellcranks at the top link point. The third connecting link connects the bottom link point on the 189 to the bottom link point on the 90 degree bellcrank. Pivots are horizonatl. Looking from the bac of the car forward, the 180 degree bellcrank's top will be tilted toward the closest wheel- the top arm of 90 degree will be tilted toward the other wheel
Roll center height is adjused by changing the length of the hub axle connecting length.
I think if yu go to billzilla's clubman site he may have a picture.
|Here are a couple of good shots of the Mumford setup:|
But bear in mind that although this does allow you to move the -rear- roll center as low as you like and eliminate roll or even cause the car to lean into the turn, it does nothing to change the front roll center, and this can be a problem if it isn't taken into account.
What are you using for a radiator in your BOP conversion? Is the rad inlet and outlet in the stock MGB locations?
|It's a custom. Brass, 5 row 3/8" tube and close packed fins but not louvered. Inlet and outlet both on the right at approx. the same location as stock except the core is longer, ~18 x 16". Fully shrouded crank mounted 6 blade 17" rigid fan. The radiator is about ten years old so if the new surge tank doesn't take care of the heat problem I'm likely to go to a crossflow design, in which case it'll be aluminum.|
|If you want to build your own panhard rod, the MG V-8 Newletter Vol. V Issue 2 pages 8 through 12 explains how to do it and also how to make traction bars. I really like the technical articles from the V-8 newsletters. |
I'm using a V8 radiator on my conversion and the hoses are from Autozone. The upper is a L 1239 and I think the bottom is a M 435. I got the parts for my lower hose from a friend who didn't remember where he got them. It is a hose that is 1 1/2 inches ID on the top and 1 1/4" ID on the bottom with a plumbing fixture in between. On the top hose I had trim about two inches off the radiator end to make it fit. The thermostat housing is a cast iron part for a '64 Buick 300 engine that point ahead, that I bought from Autozone for a little over $10.00.
Thanks to all for the good information in this thread.
This one is a keeper.
This thread was discussed between 20/12/2004 and 21/01/2005
This thread is from the archive. The Live MG MGB GT V8 Factory Originals Technical BBS is active now.