I'm working on a '58 Chevy truck and as most of you know, it's a really narrow frame so space is very precious. I set up my rear suspension and am at the point where I need to set up the panhard bar. I posted a thread earlier and asked questions on using a panhard bar mounted from pinion yoke but most of you guys said it was too short and to make it as long as possible so it won't arc as much. So this is what I came up with due to the space limitations. The bar will be mounted level with the axle at ride height and it would clear everything and when I fully deflate the bags the bracket connected to the frame will never hit the ground. My concern is that it will not be perpendicular to the axle. The other idea I had was to weld a thick wall spacer on the back of the 4 link bracket so that the panhard bar will be spaced out and parallel to the axle. Are my concerns valid or am I just splitting hairs?
Looks like it'll work to me - the only thing I'm questioning is why are you going to use that obsolete axle? Now is the time to swap something in there that has a better aftermarket support - for gears and such. Not a lotta stuff available for that axle. Just my $.02
Looks like you are running bags, are you not running shocks? I don't see why you couldn't bolt it to the top 2 bolts on the pumpkin and run a shorter bar. I have had a couple that way and they work fine. Panhard just positions the rear end, should be no stress on it if the rest of your suspension is set up correctly.
Longer is better but...the Panhard establishes the roll-center height for the suspension, it may or may not matter for your application but it's certainly lower than typical for a rear suspension...
Yes, I'm running shocks. I'm making brackets that mount off of the lower 4 link bracket bolts on to and attach the shock from there to the top cross bars. I just haven't gotten to that point yet. Originally I had it set up on the pinion yoke but it seemed that the arc would affect the travel of the chassis when the bags are deflated, so I opted to relocate it. I have 5 inches of travel down. I took a measurement 5 inches down from it's mounting point and the rod end was separated almost 2 inches from the frame.
With a panhard bar it will side squat with that much travel. It is not too late to do a non parallel 4 link and eliminate the panhard. Harley
5" of travel is a lot. Even with your long setup you will have side to side movement with that much travel. My short bar setups were not bagged and had minimal travel. Triangulated 4 bar may have been a better option with that much travel. You will probably need to set up you bar when ride height is set.
Just to ad comment to your post, with the use of air ride suspension the panard bar angle and length become more important as the ride height is changed with the air added or subtracted to the ride. If you are going to operate this car at different ride heights with the bags it might be beneficial to look into the use of a WATTS style locating linkage to locate the rear axle. This centers the rear over a wider range of drastic height changes when operating with bags and doesnt offset skew the rear as much as a straight bar. Just run the Watts pivot off the rear banjo housing with the rods to each side and it appears that this would be a livable unit so it would run true at a number of ride settings.
The other option was a diagonal track bar. A lot of folks said it was not a good idea but no one ever said why.
I don't think thats a good idea either. That diagonal bar will have a lot of stress cornering. I think your best bet is the Watts link or go triangulated.
JEM's comment about the roll center is valid. I would not mount it that low. Do not ask me how I know. Mr Spadaro's comment for a watt's linkage is very interesting. My question is when you raise or lower the truck does the angle that the bars of the watts move to cause the watts to bind. You would probably have to play with the center link length and link attachment holes. I guess build a wood mock up and move it thru the range of motion to see what happens.
Perhaps this doesn't apply to my setup but aren't panhard bars mounted below the axle up front on hot rods that use cross steering? I ask because this is where I got the idea from. Again, it might not have anything to do with my setup but i thought I'd ask.
The reason I went with a parallel 4 link is because I'm kinda building this truck on a budget and I had all these components on hand or I traded/bartered things I had for my build. I would rather find a way to make this work by relocating the panhard bar or fabbing up a watts link if need be. on the other hand it has to work properly, I will not put something on there that's not going to work or be dangerous in any way.
Go with a WATTS LINK setup, SPEEDWAY sells them and they do not cost very much. They work very well on many different configurations.
I agree with watts link! if you use a panhard bar that low, the rear is going to come around in a corner and slap the taste right out of your mouth. Rule of thumb, lower roll center in front, higher in rear. I'm not the greatest suspension man, but that is how it works!
I have the chassis set up at ride height right now. The only time I will deflate the bags is when I will park it. Do you think this still will affect the ride?
That's exactly what I would need. Mounting the watts in the rear of the diff is not an option since I have the bags there and they would interfere with one another.
I guess all these guys who say that your Panhard is too low have never looked under a NASCAR Cup car. (OK It's a little lower than I would mount it, but it will work) A lower roll center comes from a lower bar - this will generally make the car a bit more predictable and "Tighter". You can get too low for street driving (although Formula 1 cars have the roll center just about at the pavement!), but it is very common for dual duty (Street/Road Race) type cars like Mustangs and Camaro's to have the bar a little bit below the axle housing. You do want to have the bar parallel to the ground at ride height but since you have bags, you may really be better off with a watt's link anyway. On a Watts Link the roll center will be where the center pivot mounts to the rear axle housing, again, lower is better for most street cars. Most guys mount them in the center of the axle, but I think just below center is better. You need to make sure that your arms are long enough that the link doesn't bind at full travel and if you can keep them parallel to each other this is also better, especially with your long travel bagged rear suspension. Something else to take into consideration though is where your front roll center is. On a street car you usually want the rear RC a bit higher than the front RC - it just feels better to the driver.
The longer you can make it, the better it will work. Example- stand facing the wall and bend your arm at your elbow and place you fist against the wall, now move it down 6". See how far away from the wall your fist is? Now do it again, only this time hold your arm straight out from your shoulder. Your fist didn't move away from the wall nearly as much if at all. Same thing is happening to your rear axle. If you already have the parts, run them. No sense in starting over or throwing away money. 95% percent of all the big rigs on the road are on a 2link and panhard bar too.
Move the top 2 bars on your 4 link to the top, at the center, of the axle housing and change the frame ends to the proper angle and relocate them towards the top of the frame. Or get the watts link setup for the pinion from the other guy. Gene
You see a low panhard bar on the front of straight axle cars to lower front roll center,generally the end of the car with the lower roll center generates better side bite ,NASCAR stock cars run the rear panhard so low because with front a arms it is possible to get your front roll center (in theory) below ground level! Also they run antiroll bars front and rear ....enjoy you're project!
NASCAR also set a limit on the difference in height of the 2 ends. If you are using a leveling valve to set ride height and only plan to drop it lower when parked, the bags will keep your ride height pretty steady so the panhard angle will stay pretty constant.
Yes, I only plan to drop the bags when I'm parked. I'm not going to do anything fancy like side to side or anything like that and I'm also going to invest in some type of levelling system like Accuair or Dakota. The frame is set up at ride height right now and I originally wanted to put the panhard bar parallel to the ground and the axle. I just want to know if its safe and effective.
I don't see anything about your design that is dangerous, maybe not optimum, might need some anti-roll bars to get it to handle better. I don't want you to think I'm being a smart ass, but too many amateur builders want all the answers, but don't want to lay their pecker out on the stump and build something, trouble shoot it, and learn. If you fab up your assemble, take it for a ride, find out it is so bad you need to scrap it, it is only a few dollars in material and your time. We have already given you plan "B", "C", etc.
have you looked into a wishbone locator , we use them on tru unequal 4 link cars , it allows the axle to rotate on center and they are stiff enough to take cornering too and there is no side axle movement when it squats .or raises . it locates on the top of the housing , only drawback is you have to grease it every now and then .
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