525i Front Violant Shakes

[MontesCarlos]

Ok ladies and gentlemen, I have learned a whole lot from your archived postings and you have saved me a ton of money. I trust that you can help me. I mean I hope. :)
I have two 525i's; an '89 and a 92. I just bought the 92. I had heavy vibrations on the front end so the first thing I did is replace the upper and lower control arms; they were original and the car has 116k miles. I still had front end vibs, and I learned from this forum that I was missing the Hub Centric Rings for the 18" non-stock wheels. I installed the correct rings but I still have a 60-65mph shake; which I suspect are the wheels being out of balance or that the wheels are not perfectly centered. However, I get violant shakes on the front end when I am on a turn and I go over turtlebacks on the road. What would cause this? Could it be the struts? They look original.

I changed the thrust arms on my '89 525, as well as all 4 struts, not including the springs; and 99.9% of the shakes went away. The only thing I haven't changed on the '92 is the struts. Could this be causing the violant shakes? And perhaps the vibs at 60-65mph? I bought the performance rubber bushing thrust arms from Bavarian online.
Thanks in advance; and I think you folks rock.
I have some other problems but I will attack them one at a time.
I also have pictures for repairing the Sword Resistor pack if anyone is interested. I got the idea from the www.bmwe34.net site.

MontesCarlos

[Martin in Bellevue]

Swap wheels for a day. Those 18's may be knackered.

[MontesCarlos]

Swap wheels for a day. Those 18's may be knackered.

I considered that for the shakes. I will probably do this next weekend.

I'm worried about the violant shakes. I bought this car from Oregon only a few weeks ago, and now I'm hoping it wasn't a mistake. :(

Bellevue, WA eh? I'm in Marysville, WA :)

[Martin in Bellevue]

I'll make a point to announce any garage get together's, as well as Redhook lunchings. I have a spare set of stockish wheels to check for shimmy causes.

[MontesCarlos]

I'll make a point to announce any garage get together's, as well as Redhook lunchings. I have a spare set of stockish wheels to check for shimmy causes.

Thanks!

[MontesCarlos]

Folks I hope you didn't think that I have resolved my problem? I'm trying to find out what would cause front end shaking when I go over turtlebacks on a turn. I have already replaced the control arms, both upper and lower.

Any ideas??? Anyone??

Thanks

[lesage]

havve you verified that the wheels are perfectly round on the INSIDE off the rim? IE no flats...

[632 Regal]

struts.

Only reason I say that is because it was suggested you have the wheels & tires checked for out of round and balance and I'm sure you did this already right?

Next thing is that the hubcentric rings are incorrect for your wheels or somehow got damaged.

Thats it mann!

[Jr ///M5]

Violent shakes are sometimes caused by sticking calipers. It's easy to check, the car is seem to be slightly underpowered upon take off, but when you hit a bump in the road, the binding caliper will cause that side to shake violently, as if the front end of the car was bouncing.

If the car still had the original control and thrust arms, I would doubt the owner never had the brake fluid flushed. The calipers will stick in the bore because of corrosion. The problem will be pronounced when braking before a turn, or it will start to shake above 40 mph after making a stop.

Find a good straight highway, make a few moderate stops and continue for a mile. Pull the car over safely, and get out and feel the front rims for excessive heat. They should be just slightly warm, anything else would mean a caliper problem.

You can try the rebuilding method first, the seals and new rings are cheap enough as long as the caliper piston isn't pitted. Clean everything up good and re-lubricate the contact points of the brake pads and slide pins. Once you price rebuilt calipers this option will definately look better.

It's easy enough to check, and doesn't cost anything to troubleshoot it.

Hope this helps,
Jr

[632 Regal]

when that happens you usually get a severe pull in one direction or another upon braking.

Thats what I remember at least.

[Kalevera]

JR - Do you know where I can find a good tutorial on how to rebuild the caliper? I can't tell if my rotors are warped, if the caliper's sticking, or both.

I think it's probably the former - the rotors are old and have a good sized lip on them. The car sat, exposed to moisture, for a long time prior to my buying it. Problem is that I have to drive from charlotte NC to cleveland OH in the next few days and don't have the time to get the rotors and pads to do the job.

I ordered a rebuilt caliper from the fools at autozone earlier today...but as I drove the car home, it just didn't seem to be pulling - just emitting a rhythmic scratching sound SOME of the time.

The problem was much worse prior to getting it aligned earlier today...I haven't ruled out bearings, but they seem to emit the same level of sound as the brand new set that was installed in my old strut housings.

[Jr ///M5]

If the car sat for an extended period of time in the weather, the disc pads can leave deposits on the rotors and the brakes will act just as if they are warped. Look for pitting on the rotor where the pad had made contact during that time. Sometimes this can be "scrubbed" off during normal braking action, but if you can see any pitting in the rotor and you've driven it for a while now, it's probably toast and will need replacing.

I did see a procedure for rebuilding the calipers on the net, I think it was an E32 site. If you have access to a small compressor to dislodge the piston from the bore, it will help. Sorry, I don't have the webpage bookmarked. Wait a minute, here it is....http://bmwe32.student.utwente.nl/index.php?dl=sean750/vcv_replacement/VCVvalves.htm

Look over on the left of the page and find caliper rebuild.

Hope this helps,
Jr

[AllanS]

I had the same problem and it was the struts. Both of them on the passenger side were completely dead. I changed all 4 to Bilsteins and it immediately fixed the issue.