shimmy in left front wheel

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06-23-2018, 12:51 PM
hippieman9

shimmy in left front wheel

Hello everyone,
So I just got my car back together after replacing the shocks and springs. ( I had a blown left front shock) I installed the lowering springs and Spax shocks. I also installed new lower ball joints and a new steering rack and tie rod ends, and I bled the brakes since I have no Idea when it was done last.
Before I did the work, I noticed that the left front wheel would shimmy and "bounce" when applying the brakes. I figured that was due to the bad shock ( The rubber was also gone where it attached to the LCA). So I took it out for a shake down. I noticed at 65-70MPH I was getting a shimmy in the left front wheel. You can feel it in the steering wheel and floor. I also noticed when I applied the brakes there was a vibration, not felt in the pedal, but again on that wheel.
Normally I would think its a warped rotor or something. But I am not 100% sure here. I plan on having both front wheels balanced as well just to rule that out along with an alignment (since I just replaced the rack and all).
I also noticed that the car would pull to the right a couple times when braking. I am thinking I disturbed the "trash" in the brake system and now I should rebuild it. New master cylinder, rebuild the calipers, and new braided hoses.
The pads have a lot of material still left on them, But I will also check the runout and mic the rotors this evening. I am debating on having them turned or buying new.
Does anyone have any thoughts as to what would cause this shimmy issue? Thank you for any input.
Also I did look through older threads but didn't see anything quite like this issue.
06-23-2018, 10:44 PM
hippieman9

After looking at the rotor this evening its obvious Its warped. Turning it by hand there is a "tight" spot and you can see some discoloration on the rotor. I am going to look at getting them turned, There is no lip or scoring on the surface so I will try that first. As for the Brake Master Cylinder I noticed mine has a Black band on it that says its a 50:50 MC vs the stock 38:62. Does any one have any information on what is the difference? I assume that the 50:50 is the proportioning of front to back braking. Can any one offer any further insight into the difference between these two master cylinders? I am thinking of Replacing with the 38:62 stock one seeing as though I don't know how old this one is. I will also replace the stock hydrolic hoses to braided stainless, rebuild the calipers and such. May also install the EBC red stuff pads in the front.
06-24-2018, 09:25 PM
David T

Refer to ST-08-10/82 for rotor specs. A warped rotor won't cause wheel shimmy if you are not braking. An out-of balance or bent wheel causes shimmy and any play or looseness in the steering or suspension allows it to get worse. Raise the car, place a stick next to the wheel so that it just touches it and slowly rotate the wheel. If the wheel moves in and out something is wrong. If you have a sticking piston in a caliper you will get drag on that wheel and the car will lead towards that side. If one piston sticks they all will eventually so the entire brake system should be done. Check the steering wheel column bushing too. If that is worn or missing that can cause a lot of vibration. Check your tire pressures. A low tire will cause a lot of waddle and vibration. If the tires are over 7 years old don't waste any money balancing them, replace them. Have all 4 replaced and balanced and do a 4 wheel alignment. As for the master, the proportioning, while it may vary, is not all that significant but if you can get a 68/32 you are better off. Check with your favorite vendor and see what is currently available and buy a whole kit. Before ordering see if you can save the rotors. If not then you will need them too. Probably a good idea to do wheel bearings and pads too. Unless you are racing you don't need any fancy pads, the stock ones are fine. If you have a 5-speed and you have a problem with the brakes you should also be replacing the clutch hydraulics, the brake fluid in there is also probably bad.
06-24-2018, 09:39 PM
hippieman9

Quote:

Originally Posted by David T

Refer to ST-08-10/82 for rotor specs. A warped rotor won't cause wheel shimmy if you are not braking. An out-of balance or bent wheel causes shimmy and any play or looseness in the steering or suspension allows it to get worse. Raise the car, place a stick next to the wheel so that it just touches it and slowly rotate the wheel. If the wheel moves in and out something is wrong. If you have a sticking piston in a caliper you will get drag on that wheel and the car will lead towards that side. If one piston sticks they all will eventually so the entire brake system should be done. Check the steering wheel column bushing too. If that is worn or missing that can cause a lot of vibration. Check your tire pressures. A low tire will cause a lot of waddle and vibration. If the tires are over 7 years old don't waste any money balancing them, replace them. Have all 4 replaced and balanced and do a 4 wheel alignment. As for the master, the proportioning, while it may vary, is not all that significant but if you can get a 68/32 you are better off. Check with your favorite vendor and see what is currently available and buy a whole kit. Before ordering see if you can save the rotors. If not then you will need them too. Probably a good idea to do wheel bearings and pads too. Unless you are racing you don't need any fancy pads, the stock ones are fine. If you have a 5-speed and you have a problem with the brakes you should also be replacing the clutch hydraulics, the brake fluid in there is also probably bad.

Very good! Thank you. I have ordered a New BMC in 38/62, new hydraulic lines, rotors, pads, front caliper rebuild kits and stainless pistons. I will check the wheel bearings when I disassemble. The tires, from the documents from the PO, are about 5 years old or so. I have already replaced the clutch master cylinder as it was leaking into the foot well (already had the stainless line, So I flushed that system and it works great. The slave cylinder was replaced not long ago. I have also ordered a new Steering column bushing, just because I have already replaced the rack, If I knew about the bushing when I replaced the rack, I would of done it at that time too.
As far as wheel bearings are there any tell tale signs that one is bad? I see they are a sealed bearing not a timken style. anything to look for or just see if its crunchy?

Thank you again for all of the info.
06-25-2018, 10:35 AM
David T

Every tire made has a date code on it. It should be a 4 digit number. The first two digits are the week # and the second two numbers are the last two digits of the year. For example 2810 would be the 28th week of the year of 2010. If your date codes are 3 digit #'s the tires were made before 2000. As for bearings, if there is any radial looseness or roughness they should be replaced. Be careful about date codes, just because the tires were replaced 5 years ago doesn't mean they can't have already been old when they were put on. They could have been years old already. Once they get to 7 years from the time they were made (not installed) they should be replaced.
06-25-2018, 01:14 PM
hippieman9

Quote:

Originally Posted by David T

Every tire made has a date code on it. It should be a 4 digit number. The first two digits are the week # and the second two numbers are the last two digits of the year. For example 2810 would be the 28th week of the year of 2010. If your date codes are 3 digit #'s the tires were made before 2000. As for bearings, if there is any radial looseness or roughness they should be replaced. Be careful about date codes, just because the tires were replaced 5 years ago doesn't mean they can't have already been old when they were put on. They could have been years old already. Once they get to 7 years from the time they were made (not installed) they should be replaced.

Yep, Well the date codes are from 2002 and 2003. So that could be an issue too.
06-25-2018, 05:00 PM
David T

Quote:

Originally Posted by hippieman9

Yep, Well the date codes are from 2002 and 2003. So that could be an issue too.

Well then, don't waste any money on them trying to balance them. Choose what tires you want to replace them, order them, and get a 4 wheel alignment. Choices are limited if you want to use matching type tires front and rear, not sure what the best/latest recommendations are. Make sure the rims are not bent and if they are corroded the bead area will have to be cleaned up. Might as well get a new spare too. Check on the steering bushing too. Check the date codes on the new tires you are buying so you get a whole 7 years out of them.