Technical Would you guys have an issue with integrating your bump stops into the 4link?

1. The tabs would be boxed, so contact would be made on the top of the tab "box" and not the tabs alone.

2. There is NO chance of the link contacting the frame. Even if the bump stop is missing nothing can contact the link, or end link. Even with slight side to side movement, I still have a 1/2" or more of clearance between the frame and bar


3. I know this probably isn't ideal, but I can't see how it could hurt anything. It would have to completely collapse the tabs. If they are boxed, I can't see that happening unless something else catastrophic happens.

4. I would prefer not to do this, but I can't get enough angle on my bars if I don't. I also have a brake cable mount I'd have to move if they are moved inward and would prefer not to have to touch it.

 

In my view bump clearance would be a little short, raise run height to give around 3" and should be tolerable. I wouldn't worry about the boxing.

 

Integration is not the way to think of this. Interferrence? I'd put the mounting points on either end of those diagonal bars some place else, no matter what else you have to move around to make it happen.

 

Why? If these aren't bump stops, and I move them in, I have to make bump stops...

The shocks only permit 3" of compression. So I have to limit travel somehow, or the I'll blow the bottom out of the shocks.

 

That is about 3" of travel. That's why in my mind this is a winner.

It acts as a bump stop to keep the shocks from taking a beating, and gives me a good angle on the uppers.

 

If it were me, I would move both ends of the bars in, closer together and get them inside the frame then build the bump stop on the frame right in the relief you have cut out.

It's not going to hurt moving the bars in as long as you keep the angles.

It looks like your trying to keep the front of the bars on the tubing but I'd have no problem whatsoever building a bracket off the inside the tube and mounting the bars to it.

 

As those brackets sit, they are about a 25 degree angle. I plan to do as you say and move them in some and try to get to 30, but then the drive shaft starts interfering.

 

Why not add an angle bracket to the outside of the rail, and mount the bump stop to that. That way all of the geometry will stay the same.

 

My thoughts too.
Probably what they'd make you do in my country in order to be legal.

 

Don't forget if a shock only has 3" of travel but when hitting a pothole the rear end will move in a slight arc. Therefore 3" at the shock might be 4 " at the bump stop.

 

Take a deep breath and a step back. Looks like the link is a certain size and you're trying to make it work.

Move the rear end mounting point inboard, so the frame clears the mounting point. 1) this gives more suspension travel 2) it won't distort or crush the mounting point and cause the assembly to become unassemblable. 3) this will require the bar length to change or the hoops to be modified.

 

The shock is on the outside of the frame rail. About 2" away from the frame and mounted vertical. 3" of travel at it would actually be slightly less at the bump stop.

It actually equates to around 0.12". So I need to make sure the bump stop is less than that to make sure I don't ever bust a shock.

 

If you can use one bracket to do two jobs, it keeps things cleaner/simpler. Isn’t that just a part of hotrodding ? - I don’t see why not.

But I don’t understand the 4 link set up, - usually the top bars mount on the diff head and point away from each other, or are parallel- top and bottom. What is this set up called ? Thanks!

 

what he said! I don’t see any issue with mounting the bump stop as you say, but those upper arms are mounted the wrong way. You might be better off running all 4 bars parallel and running a panhard if you can’t connect the rear upper links to the center of the axle and fronts at the framerail.

 

If you move the links inboard to clear the notch you will gain more suspension travel. Then get different shocks that won't bottom out. This allows you to lower it more if you want, or just have more suspension travel for big bumps or with people in the back seat. More suspension travel is always a winner.

 

It is just a triangulated four link. Mounting them this way lowers the rear roll center slightly.

The 8.8 has a cast housing so I don't want to attempt to weld the brackets to it. Flipping the bars in this way is actually a pretty common thing to do.

 

I'd shorten the bars enough to get the ends inboard of the frame rail. I assume your shocks are coil-overs, outside of the rail, and vertical. If you angle them back slightly you gain a little more travel at the axle. And a little better ride.

 

A mustang 8.8 housing has uppers cast in. They are intrusive to the floor clearance.

How are you calculating the top bar angle when viewed from side of vehicle?
Old hamb thread with good reference
https://www.jalopyjournal.com/forum/threads/4-link-angle.759673/

Calculations for 4 link geometry.
https://www.crawlpedia.com/4_link_suspension.htm

 

Why go to all the trouble to C-NOTCH the frame...then place some apparatus that is the same amount as material removed?

 

Sorry, but shorten the upper links, quit trying to attach to tubes on the inside of the frame, make a crossmember and transfer your forces forward correctly.

You can change the CG by the elevation of the top bar in the z axis vs the bottom link bars, Putting the top bars angled down when the bottom are straight helps massively on the way the 4 link wants to bite. Your looking at 3" up travel, and 2" down probably in max setup, I would give a bit more than 3" down for loads of heavy people or other things. You notched the frame like you were going lower? Why not go lower then instead of trying to justify a bad setup and raise it up to fit link bars in? I would put the coil overs inside the frame, personally I hate seeing alot of coil over sticking out back in a car.

Pinion angle from max compression to max drop is negligible here in the setup if you shorten the upper links a few inches. That's all it will take how I am seeing it. 6" off the total length of the bar will fix your issues.

Definitely read the two links above, the upper 2 bar angles are not rocket science, 30 degrees will work... 25 degrees will work....

 

thanks !
In my head I am thinking that it probably works, (more stress on chassis internal cross member, less on outside rails), - but when I set up my car 40 years ago, I never saw it done that way, and possibly never noticed one done since.

 

1. It had leafs with a flipped axle.

2. To have room for a soft bump stop.

3. Once again....you CANNOT obtain separation on the bars. Thus again needing the clearance.

 

I have an upper bar...not shown in pictures. Problem is, with the upper cross bar, it pitches the upper arms up, and the anti squat rise above 100. I don't want that.

If you lower the bar it ends up in the drive shaft. If you mount the front links below the upper bar and clear the offset driveshaft, you lose angle.

Best case scenario with the bars the lengths they are now pinion change is right at 3 degrees. I will check shortening them, but Id venture to say it changes closer to 5 if 6" is taken off of the bars.

I like to see the coilovers. However inside the frame does give me more travel at the tires. Doing this would only put 28" between the two lower rails, and around 20" from the hub to the lower arm. That makes me uncomfortable. Maybe it shouldn't, but it does. Thats a lot more stress on the inner bars.

First time I've ever seen someone recommend a 25 degree angle...

I'll post more pictures tomorrow. This is the best I have fir now.

 

You mad bro? Are you planning on jumping and or hauling a bunch of fat chicks? I wouldn't worry about it, my cars never bottom out

 

I can't see the lower parallel bars that prevent the pinion climbing the ring gear?

 

There not in yet.

Im still finishing the frame.

 

With what I can see here is what I would mock up.

Take the bars back to the lower tube. Position wise- imagine drilling a hole right in the center of the frame tubes right on the outside of the bends, now Weld a small tube thru that frame tube. Now we have a reinforced small tube running thru the corner of the larger frame tube. This is where a long bolt goes thru and the front of your upper bar bolts to this.

3 points- 1- now you can raise or lower the rear bar mounts on the housing to get your angles back on your upper bars.
2- you will have to mock it up first to determine at what angle you to drill and Weld the tube thtu the frame tube to match the front of upper bar angle.
3- once you get this set you can build a support either front of the frame tube to wrap around the front of the upper bar mount to support the other side of the bushing or over the top of the frame bar to the other side of the bushing out of some 1/8 or 3/16 strap. Which ever way is easiest or gives you the most upper bar travel.

It's easy for me to give advice as I'm not there in to see it in person and I understand that I can't see all the angles your dealing with so I'm giving you the best advice I can with what I can see.

 

Here's a pic (worth a thousand words)

Now you can see where I'm going.

 

I will get a picture of what I am actually doing for the front mount. Ive approached it differently, but it still allows me to position it in a similar fashion to what you have drawn.

However, where you have the words "up bar", if I hold the rear housing mount inside of the frame rail as you have shown, I can only obtain 25 degrees there. Every thread on here has said that should be a minimum of 30 degrees, and preferably closer to a 45.

Stubbs said a 25 would be okay, do you agree with that.

 

Up bar just meant your upper bar.

Here's what I think. I've done frame and suspension for 40 years and there is a perfect world where everything fits perfectly but sadly we don't live in it. Ours is one of compromises and sacrifices, so with that said, we are working In a limited space and yes 30° is great but when I built mine I ended up at 28°. I even shortened my upper bars by 3", that helped greatly, allowed me to move the front of the bar out further.

IF I could only get 25° with ALL other angles in line then I would do that BUT no less.

Thru the years I've seen this problem tackled by building a truss from axle tube to axle tube over the third member and the upper links mounted close together and welded to the truss. Another built a 1/2 plate that matched the rear cover and then sandwiched between housing and rear cover then the upper bar brackets were welded to that.

It also depends on how you drive the car on the best way to design your system in limited space, race car? Then I wouldn't use the sandwiched plate but no problem building a truss. A driver? Then I wouldn't mind the sandwiched plate.

So 25° with other angles good on a driver? Yes I would, again space vs. Optimum design.

Here's a pic of mine, again compromises. I built frame, 4-link brackets, quarter elliptical springs, spring brackets etc. The only thing I didn't build are the housing and the bar ends.