Yet another Rear control arm design

[JMortensen]

Make sure you guys are looking at the axial load ratings for the rod-ends you're using. The bearings are loaded axially under accel and braking on most of your control arms, and the axial load rating is significantly lower than the radial load rating.

I have two rod XMR12 ends that I'm using with spacers to size them from 12 to 10 (smoking crack one day and ordered 3/4 instead of 5/8). I have two more oversize rod ends XMR10-12 which have a 3/4" shank and a 5/8" hole in the ball, and I have 2 XML10-12's to go with them for the turnbuckle. The regular 12 surprisingly has a lower radial load rating than the 10-12.

 

I checked the rod ends I'm using (QA1 XM) and found the following radial ratings:

 

40572 lbs for the 10-12

28081 lbs for the 12

 

I read that normal axial load ratings for a 3 piece rod end are 10% of the radial rating, these are 2 piece and are supposed to be good for 30%.

 

What I'm thinking is that I should put the 12 with the spacer in the clevis on the control arm for the toe link. That would mean that this particular end would be loaded radially since it is turned 90 degrees from the spindle, and then run the 10-12 ends on the front and back ends of the spindle. Sound about right to you?

[tube80z]

I don't see how you're going to get any radial loading on the toe-link. And a season of abuse has shown no issues in ours.

 

Cary

[Flexicoker]

I can't picture what you're describing, Jon. but if you've got a simple way of flipping the rod-end 90* so you can load them radially all the time, thats pretty awesome. I'd like to see a picture of what you've come up with.

[tube80z]

There are different ways to do it i,i made them with fixed track and just adjustable toe in/out they are made from thin wall 4130 tube

 

Really nice work!

 

Cary

[Flexicoker]

If its just a toe-link, it should already be loaded radially. Axial load on a spherical bearing is when the load is along the axis of hole in the ball, not the treads. Think about it this way, if you're force is pushing the ball against the race, thats radial load, and thats good. If your force is trying to push the ball out of the race, thats axially, and that is the incorrect way of loading a spherical bearing.

 

Ok, Jon, I think I see what you're asking now. i'm looking at your picture on post #101. Your toe-link is going to load the bearings radially in either orientation. Your toe-link is a true "2-force member," which means that the link itself, is loaded axially. This is the application rod-ends are designed for. You're other outboard rod-end is going to be loaded axially on accel and braking, and radially under cornering, that rod-end is going to be taking all of your longitudinal force for that wheel. Now, your bearings are pretty huge, so they can probably handle that. I would recommend finding the actual load rating from the manufacturer. I was looking at the aurora website last night and some the axial load ratings were closer to 5% of the radial rating, FAG doesn't even give an axial spec, they just say don't load them that way.

[JMortensen]

Duh. Of course the toe link won't be loaded axially. Brain fart...

 

I double checked the numbers I had since they came from a website other than the manufacturer. Turns out the 10-12 number was way off. The XMR10-12 is actually rated at 31680 lbs. So that's a lot closer than the original numbers suggested and I'm inclined to leave it alone.

[MoNkEyT88]

Where are you guys getting your weld in ends?

 

It doesn't look like the "chassis shop" carries them anymore.

[z-spec]

Where are you guys getting your weld in ends?

 

It doesn't look like the "chassis shop" carries them anymore.

 

I have seen them some where , but try your local machine shop to make them ,

[74_5.0L_Z]

I just got the new ChassisShop catalog. The weld in ends (AKA tube adapters) are listed on pages 9 and 10.

 

Here is a link to help you find the tube adapters on their web page:

 

http://secure.chassisshop.com/categories/5625/

 

Finding them through their web menu was impossible. I had to search their site using the key words, "tube adapters."

[proxlamus©]

First, let the part cool completely after welding.

 

Use a torch with a rosebud tip and get a 900F temperature crayon (Tempilstik). Mark each side of each welded joint with the crayon 1" from the weld. Use the torch to heat a joint until the crayon marks melt. Cover the joint with a heat blanket or something to slow the cooling process down. Proceed to the next joint. If you're really anal, heat all the joints equally and at the same time before letting the part cool down.

 

What you're trying to accomplish is to relieve any stress buildup and resulting distortion from the welding process.

 

EDIT: Before you go through all of this, you can take the part out of the welding jig and see how much distortion exists. If its just a little bit, I probably wouldn't worry about stress relieving the part.

 

 

Is there anything wrong with heat quencing?! Rather then allowing the part to gradually cool down.. why not dunk the part in a bath of oil. This would work harden the part dramatically.

 

or should suspension parts avoid work hardening?!

[MoNkEyT88]

Found this on Lincoln Electrics site about welding 4130. Chrome Moly.

 

Q. Should I quench the metal after I finish welding?

A. ABSOLUTELY NOT! Rapid quenching of the metal will create problems such as cracking and lamellar tearing. Always allow the weld to slow cool.

I've even heard that a heat blanket should be used over the part to let it cool slower.

 

 

Q. Do I need to pre-heat?

A. Thin wall tubing (< 0.120" wall) applications do not typically require the normal 300ºF to 400ºF pre-heat to obtain acceptable results. However, tubing should be at room temperature (70ºF) or above before welding.

 

Q. Do I need to heat treat (stress relieve) 4130 after welding?

A. Thin wall tubing normally does not require stress relief. For parts thicker than .120", stress-relieving is recommended and 1,100ºF is the optimum temperature for tubing applications. An Oxy/Acetylene torch with neutral flame can be used. It should be oscillated to avoid hot spots.

[JMortensen]

Back to this about 14 months later. Got these installed and checked them out for fitment, etc. Everything looks good except the rear rod end was very close to binding against the strut housing. I suppose I could have radiused the end of the strut housing with a grinder, but instead I grabbed a couple 1/8" bumpsteer spacers I had laying around and added them between the rear rod end and the strut housing. With them in place everything looks peachy, and due to the freedom of motion in the toe link the addition of the spacer shouldn't be a problem. Working on installing the whole suspension, doing a final once over on it, and then I'll be plumbing fuel and brakes.

 

 

 

 

 

 

 

 

Edited March 3, 2010 by JMortensen

[tube80z]

Looks good Jon. I used rod end spacers against the struts on mine and safety washers on the outer ends just in case. I hope you have better luck with the slot gap bearings but we needed to change to real three piece rod ends as the others were sloppy after one weekend of use.

 

Cary

[EMWHYR0HEN]

Looking good Jon.

 

Are you using 3/4'' rod ends? I noticed they look a lot bigger than mine. I like the use of the spacer between the rod end and spindle. I better check mine for bind.

[JMortensen]

They are 3/4" rod ends. Hopefully they hold up...

[JMortensen]

 

One thought keeps rolling around in the back of that hollow cavernous cranium of mine. I keep thinking that by putting the bolts through the monoball and screwing into the arm on the inner joints, I essentially have the arms mounted in single shear. It's "double single shear" since the arms have a bolt on each end, but I'm now wondering if I should drill the threaded bungs out, cut the heads off of the bolts and slide them in backwards and use nuts on the outer ends.

 

Wouldn't take that long to do. On the other hand, the stock arm had a tin walled tube with threading cut into it and I have a 5/8" grade 8 bolt so maybe I shouldn't worry about it.

 

[ModernS30]

I have one question. Something constantly sought after are 5 lug swaps and brake upgrades. Why when building these control arms does everybody limit themselves to other factory parts? If you are building custom control arms? Why Not do it all the way around and adapt something like 240sx parts or even Skyline GT-R parts? Or who knows? Maybe something non-Nissan that can be made to work and adapt a 5 lug for great wheel options as well as larger brakes without the hassle of other custom brackets and the hassle of sourcing parts. This is just a thought, I think you are really limiting yourself utilizing the factory Datsun Knuckle and strut tube setup.

[JMortensen]

I have one question. Something constantly sought after are 5 lug swaps and brake upgrades. Why when building these control arms does everybody limit themselves to other factory parts? If you are building custom control arms? Why Not do it all the way around and adapt something like 240sx parts or even Skyline GT-R parts? Or who knows? Maybe something non-Nissan that can be made to work and adapt a 5 lug for great wheel options as well as larger brakes without the hassle of other custom brackets and the hassle of sourcing parts. This is just a thought, I think you are really limiting yourself utilizing the factory Datsun Knuckle and strut tube setup.

If the intent is to run 5 lug you can get there by redrilling the stock stub axle at basically no cost. If custom brake brackets are too much hassle for somebody, then I wonder how that person justifies retrofitting an entire suspension system from a different car or designing and fabricating a new suspension. Bolting on brackets is relatively easy. If you look at the 240SX rear brakes, they're nothing to write home about, so those would need further upgrades to keep up with a Wilwood type system that is commonly used on the stock strut. I think the Skylines used the same brakes as the 300ZX, again, I think judging by piston size, rotor diameter, and pad size the common Wilwood setups are bigger.

 

The stock Z rear suspension's main limitation is the H arm IMO, and the arms that have come out of this thread have addressed that problem. The stock system has some pretty big advantages over 240SX or Skyline rear suspensions. It weighs a lot less and has no dynamic toe change, and again with the arms in this thread the issue of bushing deflection has been eliminated. If you really wanted to change to something else, I would be inclined to go SLA suspension instead of 5 link, but that is quite a big project in relation to making a new control arm or drilling the stub axle and bolting on bigger brakes.

 

If you have a better system from a different car from another manufacturer that is easy to retrofit, by all means post all about it and people will start doing that. Right now it seems like your only point is to **** up this thread.

[ModernS30]

If the intent is to run 5 lug you can get there by redrilling the stock stub axle at basically no cost. If custom brake brackets are too much hassle for somebody, then I wonder how that person justifies retrofitting an entire suspension system from a different car or designing and fabricating a new suspension. Bolting on brackets is relatively easy. If you look at the 240SX rear brakes, they're nothing to write home about, so those would need further upgrades to keep up with a Wilwood type system that is commonly used on the stock strut. I think the Skylines used the same brakes as the 300ZX, again, I think judging by piston size, rotor diameter, and pad size the common Wilwood setups are bigger.

 

The stock Z rear suspension's main limitation is the H arm IMO, and the arms that have come out of this thread have addressed that problem. The stock system has some pretty big advantages over 240SX or Skyline rear suspensions. It weighs a lot less and has no dynamic toe change, and again with the arms in this thread the issue of bushing deflection has been eliminated. If you really wanted to change to something else, I would be inclined to go SLA suspension instead of 5 link, but that is quite a big project in relation to making a new control arm or drilling the stub axle and bolting on bigger brakes.

 

If you have a better system from a different car from another manufacturer that is easy to retrofit, by all means post all about it and people will start doing that. Right now it seems like your only point is to **** up this thread.

 

By no means is that what I was doing. I was just asking for an answer to that question. You gave me the answer, your last comment was unneeded. I already had custom brackets CNC cut for disks on the rear of my car. Like I said, you gave me an answer, its seems like a solid answer with good reason.

[JMortensen]

Seems like bad form to me to post on a thread 7 pages long questioning the point of the thread, especially when there are other threads about putting 240SX suspension and SLA in these cars already and the question "why don't people focus on the rear suspension as much as the front" has come up probably 3 times in the last couple years.