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44 votes
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Why do the brakes "freeze" the suspension?

I made a crude sketch illustrating the relevant points of the shown image. Brakes engaged: The center of gravity is above ground, the brakes "try" to slow down the car, the car itself "...
Martin's user avatar
  • 8,448
27 votes

Broken Coil Spring - How urgent is the repair?

That spring can rotate and rip out the tire - catastrophic loss when entering a bend could mean driver, occupants, other drivers, and/or bystanders could be singing with the angels... Ground the car ...
Solar Mike's user avatar
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21 votes
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Discovered disconnected part when removing wheels

I agree with @resident_heretic that these are the link arms for your stabilizer bars. The bar acts as a torsion spring that tends to keep the car level during cornering. With the links broken on the ...
dlu's user avatar
  • 14.5k
20 votes

Why is my car losing control and vibrating

The only way for a sway bar to bend would be an accident, so you are right to suspect they are full of it. It sounds like whoever did the suspension work botched the job and are now trying to cadge ...
GdD's user avatar
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16 votes
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Motorcycle Speed Wobble - How do I figure out the problem?

Motorcycle Speed Wobble Troubleshooting Troubleshooting speed wobbles can entail looking at quite a bit. Here are some bullet points on components you need to check on your bike for integrity and ...
DucatiKiller's user avatar
  • 32.9k
16 votes

Broken Coil Spring - How urgent is the repair?

My biggest concern with issues like this is causing additional damage since the spring is no longer being supported the way it was designed to be. Also, the rear suspension is (obviously) compromised,...
jwh20's user avatar
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15 votes
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Reusing self locking nuts

I'll make a couple of cogent points, but I doubt I'll be able to organize this coherently. Go get and read Carrol Smith's Nuts Bolts Fasteners and Plumbing. This is religious tome-level knowledge ...
SteveRacer's user avatar
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14 votes
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Spring tensioner safety

I use two part spring compressors like you show here on a regular basis.* I think you'll be fine but there are some good things to watch out for. Watch out for the threads. If the compressing ...
Bob Cross's user avatar
  • 24.4k
14 votes

Discovered disconnected part when removing wheels

Looks like a stabilizer bar link. They come in pairs one on the left and one on the right side. They attach to the stabilizer bar. Stabilizer bars are part of a car's suspension system. They are ...
Old_Fossil's user avatar
  • 3,962
14 votes
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Vibration at speeds between 40-47mph

Hitting a bump at speed can cause several problems: Tire or wheel damage: generally this requires a replacement tire or wheel Suspension damage: a suspension member could have been bent or damaged by ...
GdD's user avatar
  • 16.9k
13 votes

Broken Coil Spring - How urgent is the repair?

The basic issue from a mechanical point of view is that the spring (not the shock!) is what supports the weight of that corner of the car. Clearly, with a piece missing, it is not doing that as it was ...
alephzero's user avatar
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11 votes
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What are the advantages of upside down forks?

There are several advantages to upside down forks Rigidity Caliper Mounting Stability Reduced Unsprung Weight Reduced Sprung Weight Reduced Stanchion Friction Levels Increased Stanchion to Slider ...
DucatiKiller's user avatar
  • 32.9k
11 votes

Pros and cons lowering sedan?

For God's sake don't I'm still to see a car that was lowered properly. From what I can remember now you will have these issues: The car will jump at every small irregularity in the asphalt. Wheels ...
Gabriel Diego's user avatar
11 votes

Why do race cars need suspension?

Suspensions do two things: they smooth out a bumpy ride, and as such are more of a comfort thing. In fact, production cars have their suspensions tuned at the factory for some kind of compromise ...
tlhIngan's user avatar
  • 12.2k
11 votes
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Is alignment needed after replacing upper control arms?

ABSOLUTELY Yes, when you do any major work to the front suspension, you need to have the alignment done. Even though the parts are "basically" the same, they are not exact. Newer parts will be ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
10 votes
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Effects of sway bar stiffness on rough, uneven roads

tl;dr: stiffening one of the sway bars on a car will cause that end to be more likely break loose in response to transients. At a high level, the sway bar acts as a spring just like any other. You ...
Bob Cross's user avatar
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10 votes
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Wish to understand why non-stock vehicle alignment is an issue

Factory specs assume factory parts. Each modification you have made changes the angles at which the suspension operates so those angles no longer apply. This is especially true on truck lifts where a ...
finleyarcher's user avatar
10 votes

Why do the brakes "freeze" the suspension?

As it turns out the answer is very obvious and frankly quite simple. Consider a 1 meter long plank. Now if you lift up the right side of the plank by 10 cm (0.1 meter), the left side moves a bit to ...
user60481's user avatar
  • 1,339
9 votes
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"Always Replace" (torque-to-yield) Bolts

I cannot tell you directly if the bolts you are using are Torque to Yield (TTY or T2Y) bolts, but if Bently says to replace them, you bet I'd do it. What are three bolts in comparison to the well ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
9 votes
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How did luxury cars provide smoother rides without active suspensions?

Assuming they were the base models, the two cars you mentioned (Acura TL and Mazda6) are both Front-Wheel Drive (FWD), while the Mercedes is Rear-Wheel Drive (RWD). The FWD cars, having both their ...
MooseLucifer's user avatar
  • 6,007
9 votes

How to demonstrate that rear shocks are failing?

There should be no oil visible on the shocks. If you see oil that means they're not damping as they should be because the seals are compromised. They most certainly shouldn't be dripping, regardless ...
Zaid's user avatar
  • 39.1k
9 votes

When to replace struts?

Those look very worn to me. Of course it's your choice, unless your locality requires vehicle safety inspections, to keep driving on worn suspension parts but it's not the safe choice. The fact that ...
jwh20's user avatar
  • 12.1k
8 votes
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Ohlins Rear Motorcycle Shock - How do I setup, care for and tune it?

Overview In terms of rebuilding the shock, there are similarities between models but there are unique differences between them that make it impossible to review all of the nuance. I'll only give a ...
DucatiKiller's user avatar
  • 32.9k
8 votes

Effects of sway bar stiffness on rough, uneven roads

Adding a sway bar will result in a harsher ride I've tried to explain the mechanics with this side-by-side graphic: Explanation When a wheel encounters a ditch, the weight of the vehicle on that ...
Zaid's user avatar
  • 39.1k
8 votes
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What is the difference between a knuckle and spindle?

The knuckle is the part the spindle attaches to. The spindle carries the hub and bearing(s). Generally the spindle is used on non-driven wheels, but there are some where the spindle is hollow and the ...
Ben's user avatar
  • 10.7k
8 votes
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Torquing Strut Nut with Tire on Ground

You should leave them just about snug, if not just a little loose. If you tighten them before you put it on the ground, when you do get the car on the ground, there will be tension on the parts, which ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
7 votes
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How bad is this strut mount damage?

Strut mounts that tear a little are safe to drive with. The mounts themselves have metal inside them and are conically shaped at the top so they really won't fail unless you take the vehicle airborne ...
cloudnyn3's user avatar
  • 3,333
7 votes

Why are shock absorbers in wishbone suspension systems mounted on the lower control arm?

The late 60s to early 70s mustangs has shocks and springs on the upper control arms. Normally They are installed on the lower control arm to save space. By fitting them between the control arms the ...
vini_i's user avatar
  • 16k
7 votes

How to demonstrate that rear shocks are failing?

Do the knee test. Start at the front, since those shocks are assumed to be good, because they are new. Put your knee on the front bumper in one corner, put all your weight on it, then get off. Count ...
tlhIngan's user avatar
  • 12.2k
7 votes

Broken Coil Spring - How urgent is the repair?

The last three quarters of a turn of the spring is flat, and coiled to a smaller diameter than the body of the spring, so that it can sit snugly around the locating nub welded onto the frame, with the ...
Phil G's user avatar
  • 1,087

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