Suspension and steering parts wear tests

[timpnw]

Turns out there was a wheel spacer installed by PO, I missed in there causing the squeak. The springs are good. RTABs installed. Took way longer than I thought, however, the second side took half the time. Existing RTABs had no visual degradation. The rear alignment was jacked up with uneven wear on previous tires, so no regrets about changing them out.

[sapote]

I'm assuming it's the strut but could be the spring... no rust on the car so I don't know why the spring would squeak like that.

Spring movement should make no noise, unless there is a gecko in between the spring coils.

[jet_dogg]

For me...clutch module.
It's nla.
The solutions are to buy the older switches and sub harness to convert.
Or buy a euro switch and recode.

I also own an E30 M3 and there are a lot of wearable parts that are nla.

Pff, I know that feels bro.

I bought a new alternator just to have as backup since I thought they were going nla. I'm going to have to pick up some pillars, rear parcel, a spare center console and some other bolshit soon just in case.

[FBloggs]

Great, which factory only parts are we talking about?

For me...clutch module.
It's nla.
The solutions are to buy the older switches and sub harness to convert.
Or buy a euro switch and recode.

I also own an E30 M3 and there are a lot of wearable parts that are nla.

[jet_dogg]

^^^
This is it really.
Do it all now.

Prices are shooting up.
Availability of factory and 3rd party replacements is spotty.
Quite a few Factory-only parts that are almost vital to keep the car running are NLA.

Before I acquired this car, I would attempt to diagnose instead of throwing parts at it.
It seems like one should not procrastinate with the replacement of wearables that are now getting scarce or are of sub quality.

Great, which factory only parts are we talking about?

[FBloggs]

Just change everything and be done with it. No telling how the POs drove the car.

The peace of mind is worth it and you can only regret not doing something.

^^^
This is it really.
Do it all now.

Prices are shooting up.
Availability of factory and 3rd party replacements is spotty.
Quite a few Factory-only parts that are almost vital to keep the car running are NLA.

Before I acquired this car, I would attempt to diagnose instead of throwing parts at it.
It seems like one should not procrastinate with the replacement of wearables that are now getting scarce or are of sub quality.

[timpnw]

Alrighty. I'm ready to tackle FCABs and RTABs. The only thing the jounce and rebound test revealed was a very loud squeak from the driver's rear... that was louder pushing down and quieter on recoils. I'm assuming it's the strut but could be the spring... no rust on the car so I don't know why the spring would squeak like that. Ideas? Am I on the right track?

[Arith2]

Arith2 Wow. I can't believe after all these years I've neither heard of the word 'jounce' nor of a "jounce and rebound" test. I've now watched 5 youtube videos on it... Thanks for the education. This is exactly what I was inquiring about.

$35k and a technical degree to learn dumb crap like that 😂

I'll gladly spread as much of that knowledge as I can. Warped Perception is a youtube channel that has some awesome videos to help you visualize the theories also.
Here's a list of cool channels. I don't think all are still active but most should be.

KYLE.ENGINEERS
Warped Perception
Engineering Explained
driving 4 answers(very informative on history also)
Julian Edgar
GraysGarage(pretty sure inactive but still good info)

If you like rockets, Everday Astronaut is probably the best, and most understandable channel for that. He doesn't do cars but they are still giant engines which might peak your interest.

[timpnw]

Arith2 Wow. I can't believe after all these years I've neither heard of the word 'jounce' nor of a "jounce and rebound" test. I've now watched 5 youtube videos on it... Thanks for the education. This is exactly what I was inquiring about.

[LSB4Me]

My 1966 Porsche still has the original lower control arm ball joint with over 300K miles. As long as the rubber boot not torn, no rust and zero plays, I will continue driving.

Slightly off topic but I have a 71 911T and almost went the same route. I think the original Porsche stuff was really over-engineered and the old, light cars simply don’t wear stuff out. That said, I did a suspension refresh and opted to change everything—on the 71 and my e46. Couldn’t help myself.

[Arith2]

Everyone mostly talked about bushings which is fine. I'll focus on springs and shocks.

The test is a jounce and reboud test. The literally compress the suspension on each corner. You cause the first jounce by pushing. It should rebound a little past where it settles and the slightly jounce back into the resting position. There should only be one rebound and one slight jounce. If it does it more, shocks are worn.

Checking spring can be as simple as checking ride height or any creaking. Look for rust and my rule of thumb is almost always do shocks AND springs for a good set up. Steel fatigues and if the shocks are worn, the springs are working overtime.

Missing bump stops are a red flag. You need bump stops. There is a maximum travel for the shocks. This is why just lowering springs are stupid. The dust boot is just helpful. Rear lower bushing is always torqued with the vehicle weight on it. This can be done with 4 tires on the ground and slightly lowered.

[sapote]

My 1966 Porsche still has the original lower control arm ball joint with over 300K miles. As long as the rubber boot not torn, no rust and zero plays, I will continue driving.

[jet_dogg]

At the bare minimum I would change without a doubt the following:
-front control arm bushings which are notorious for going bad quickly on most bmws
-rear trailing arm bushings (i have monoball myself)

I'm of the school of thought that says its time or will be time and you can restart the calendar on your watch since you took ownership. If you check them and they're good they won't be good for long and you can't measure incremental deterioration.

Start with the above first and then do these later as a refresh,

Front axle
-tie rods
-front control arms which house the ball joints

Rear axle
-new bushings for the lower wishbone or preferably new adjustable camber arms
-front diff bushing and rear diff cover with new bushings preinstalled since you can't purchase the pair separately
-solid subframe bushings

At 100k I'd do the four ball joints on the rear trailing arm, two on each side upper and lower along with the sway bar bushings and end links.

[timpnw]

sapote solid advice. Thank you. The car comes out of storage this weekend. I'll be doing what you said. I'm usually with @jett_dogg but I'm deep in this thing as the PO was terrible and I hastily bought it b/c it had the cinnamon interior. Anyway, I budgeted $5k after the purchase and that went fast as I outsourced the work that I was not planning (clutch,vanos and tires). I had an e39 540 in pieces at the time and couldn't have two cars apart and keep everyone in my house happy, Now that I have another car in the stable I can put this up on the stands for a week or so and get down to it.

[sapote]

How do you know when it's time to replace...

I would do this instead of just changing everything:
*For front lower control arms bushings and ball joints check: jack up only one wheel off the ground and leave the other on ground, then hold the wheel at 3 and 9 o'clock and rock it back/forth, and repeat at 12 and 6 position. If there is no noticeable plays then they are still good. If there is plays at 3/9 position, look to see if the arm is moving within the rubber bushing (in the lollipop) then only the bushing is needed, but if the plays is at the ball joint (most of the time it's the outer ball joint) then either replace the joint or the whole arm depending on the skillset or parts availability. All check the steering rack tie-rod rubber boots for tear and replace.