Adjustable lower trailing arms discussion.

[ronny 204]

I agree Thom

Im using Mcdonald adjustable uppers and standard lower with rock hard bushes

Good enough for getting the pinion angle how i want it

[n00bus m@x1mus 465]

Is there any easy way to tell the difference?

 

Its quite obvious when u see them, the pin is below the diff filler plug instead of in line

 

A terrible picture to describe it i know but if you look closely you can make out the difference.

 

 

Plus notice the hand brake cable route on the face of the cover also.

[mcfly94 169]

 

Its quite obvious when u see them, the pin is below the diff filler plug instead of in line

 

A terrible picture to describe it i know but if you look closely you can make out the difference.

 

 

Plus notice the hand brake cable route on the face of the cover also.

Damn I cannot find one any where, need to try find one at the wreckers!

 

Just a thought on, diff pinion angle, I have slight issues with clunking in reverse and reckon its the tailshaft, could the diff pinion angle be playing apart in this, moving the uni in an awkward position?

[n00bus m@x1mus 465]

In addition to the watts link pivot pin dropping with the AUs  they also shortened the top arms by around 30mm aswell, my guess is to increase that roll forward rate as the diff goes up into the body.

 

Also note the tidy box section used and both bushes are the same part front and back.

 

 

 

[ILIED 316]

Are we sure the diff mounts for the top arms are in the same position?

[n00bus m@x1mus 465]

Yep if u look at the first pic i put up that was exactly what i was measuring. Swapped arms from one to the other and the hole in the top bracket is the same distance from anywhere on the diff housing. I cant say if its the same in the body but.

[Crazy2287 1,886]

So this is the final idea for the lower arms. This is a to scale drawing of the components that will make it up.

I asked the machine shop for max cost to have the threading done and he said $70 each. The bush receivers on the end will be salvaged from the old arms. only about $20 worth of steel. So will be $160 or under + time to put em together.

 

 

Will use 33mm OD black tube with 4.5mm wall. Weak spot will obviously be the internal thread.

Design allows for 11mm of adjustment in and 30mm adjustment out.

 

Thoughts?

[Thom 6,654]

You going.to use a lock nut/jam nut to stop them from self adjusting?

[Crazy2287 1,886]

the exact purpose of the little collar with the '13' above it.

 

It won't be able to adjust by itself due to it's design. but the collar will take out small movements within the thread which would otherwise fatigue the thread over time.

[Crazy2287 1,886]

So it's 55 bucks a pair for the bushes. 70 bucks machine work and about 10 bucks steel per arm. 135 bucks per arm. 270 for both plus probably 8 to 10 hours to build it.

 

Its borderline not worth it. You can get them ready to go for probably under 400 inc post....

[Crazy2287 1,886]

So confirmation on the prices.

Make my own = $250 the lot + my time. Get it by the end of next week.

Purchase = $420 inc post to my door. get it the week after next.

 

What do...

[Thom 6,654]

What do you have more of at the moment, time or money? (or neither)

[Crazy2287 1,886]

Neither, But such is life in the 21st century.

Assuming i get up in the morning and don't play video games i can make the time. It will have the side effect of improving my hand skills.

 

On the other hand, If i ask really nice i'm about 95% sure the misses will buy me the premade ones.

[mcfly94 169]

So confirmation on the prices.

Make my own = $250 the lot + my time. Get it by the end of next week.

Purchase = $420 inc post to my door. get it the week after next.

 

What do...

you might enjoy making them?

I know id make them myself if I knew I could produce the same quality

[XES 859]

You know you'd get a lot of satisfaction out of making them yourself tho Q. Can you make them better than the bought ones tho? Better quality , maybe better adjustment?

[Crazy2287 1,886]

well. same same really.

 

I'm not sure on the production method for the brought ones.. Are they tempered? What steel do they use?

 

It will come down to welds really. I will have 0.7mm increments. Brought ones will have infinite adjustments between max and min.

if i can get the steel hot, then weld it with lots of amps and a slow wire speed i will get really good joins. Will need to practice first the hit it.

 

Af for what is better... i can't say at this point. they are using 44.5mm x 3mm tube for lower arms. Mine is 33 x 4.5mm. It's a tuff one.

 

 

 

MIGHT cut a std lower up tomorrow and see how long it takes......

[Thom 6,654]

One thing I like to do when making 4 bars/ control arms I use late celica lower arms (last of the rwd models) easy to get various sized bushes for plentiful at wreckers.and very easy to modify as they are already a tubular control arm.

[Crazy2287 1,886]

Pick up the machined arms tomorrow. Just gotta weld these onto em:

 

Geez, i hope i don't need these anymore...

[Crazy2287 1,886]

 

 

preheat, then lots of heat. 2 passes. Slow air cool.

 

cold gal, stone guard. bushes in. Set to 3.5mm longer than factory.

 

 

end cost was $240 bucks after everything. 2 days work.

[Thom 6,654]

Looks good Q, so the question is does it drive better?

[n00bus m@x1mus 465]

I like your style bruz... top marks, looks like a tradesman did it.

[Campo 869]

Looks good mate!

[Crazy2287 1,886]

Here is some interesting information guys:
http://www.therangerstation.com/Magazine/winter2007/4_link_tech.htm

It's a big read though.
But it talks about about the engineering considerations for setting up 4 link suspension which carries over to a lot of other things.

I figured out the arms i made apparently with that steel have a 1.4 load factor for that corner. rough calculations but it means i could jack that wheel off the ground from the center of the trailing arm. Which is the MINIMUM you want really. Impact will exert a lot more pressure.
The steel i used was apparently a-53 with a 30000psi yield strength. Anyone planning to make their own should try and get that same size pipe but in 1020 DOM grade whatever the fek that is as it will give double the strength and can still be welded easily.

Prolly should have looked this up first. ROOKIEEEEEEEeeeEEEe.

The only thing i looked up was minimum required thread engagement for maximum strength. Steel aint steel. Every day is a school day.

Also going to have to get or make a tool to check and set the pinion angle now that i can... Gonna be a bitch? maby......
 

[n00bus m@x1mus 465]

When u work out that tool post up your findings cos im going to need one soon too .

[Crazy2287 1,886]

So i built a pretty simple tool for measuring the angular difference of the uni's

Basically i put this in photoshop and drew a square border around it: 

http://upload.wikimedia.org/wikipedia/commons/7/70/Protractor_Rapporteur_Degrees_V3.jpg

 

then printed it out and cut around the border exactly to ensure all edges were square.

Then glued it to a piece of board.

Cut the board to the size of the protractor making sure edges were square and straight.

Welded a small nut to one end of a piece of 5mm rod i had as scrap. and cut it to length, grinding a point on the end. Passed a screw through the nut and screwed it into the zero intersection of the protractor.

Pulled it apart and put a little grease on it then put it back together. This is my protractor needle, Works like a plumb-bob and complies to gravity. Thus it won't show you the angle, only angular difference. Which is what you want anyway.

 

Got a spirit level out and set it level. then placed my tool on the level to check for 90 degrees. Used this trick to calibrate the protractor needle.

 

Checked the diff and got 1.75º down. could not figure out how to check the transmission. Googled it and apparently you pull the tailshaft out and measure off the output drive end. Can be done but thats tomorrow. Then i'll know both difference i am supposed to tune them to be identical and +1-2º down on the diff.