View Full Version : Rear tire rubbing on spring
I have a new complete kit with IRS and 17" wheels. In retrospect I should have mounted the rear wheels once I installed the IRS, but instead waited until I mounted the brakes. Now, I have a problem as I cannot even get the wheels on due to interference with the springs. Both sides have interference. I still have the car on floor jacks, so this problem may go away once it gets under weight, but I am not sure and don't know how to get it under weight without the wheels mounted correctly. Also, I have not done anything to align the IRS yet. Are there any starting measurements like the front suspension? I was waiting to get the tires on the ground before the rear alignment, but that will not be possible as things stand. Last, should I simply turn the coilover upside down? Will that fix things sufficiently for now?
Thanks
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chjort
03-09-2023, 12:17 AM
I had the same problem. Once you set the correct ride height and have the car on the ground with the alignment adjusted, I think you will find that the tire no longer rubs on the spring.
facultyofmusic
03-09-2023, 02:47 AM
Same problem here except I couldn't get it to not rub the springs while it's up in the air. Like yours, when the suspension goes underload it's fine. It only rubs when it's in midair. I ended up buying two 5mm spacers that solved the issue. (here's the amazon link if you're interested (https://www.amazon.com/gp/product/B01MRIB441/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1))
I've got no masters degree in suspension design but I think 5mm is fine. It depends on your wheel's offset anyway.
edwardb
03-09-2023, 05:39 AM
Two IRS builds. 315 size tires (normal max size) with 18" FF wheels. After ride height and alignment set they don't rub on the springs. Both on the ground and in the air. I have a lift so they're up in the air somewhat frequently. Spacers aren't needed and in fact could possibly conflict with the body wheel well opening. I set the adjusters to roughly mid-point during assembly and they didn't rub then either. Although were quite a ways off when time for actual alignment. BTW, important to get the adjusters centered and equal threads showing on each side as pictured. Provides maximum adjustment.
https://hosting.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/.highres/IMG_0152_zpsixzfry84.jpg?width=960&height=720&fit=bounds (https://hosting.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/.highres/IMG_0152_zpsixzfry84.jpg?width=960&height=720&fit=bounds)
https://hosting.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/.highres/IMG_0153_zpsshxrqbwz.jpg?width=960&height=720&fit=bounds (https://hosting.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/.highres/IMG_0153_zpsshxrqbwz.jpg?width=960&height=720&fit=bounds)
Norm B
03-09-2023, 04:22 PM
I don't know anything about the IRS or the associated shocks but, if possible, could the shocks be installed the other way up? Would that buy you more room?
I am sure one of the experts will tell me to PFO if appropriate.
Norm
JohnK
03-09-2023, 04:27 PM
Edwardb has it right. With the suspension at full droop and nothing aligned, everything will look all out of whack. I had the same exact concerns when I first saw my rear suspension after I assembled it. Once you get things roughly aligned and get the rear on the ground it will look more normal.
Thank you all, you were spot on. And the pictures from edwardb were great. I set the spacing to about 5 to threads on each side for the upper control arm and 6 threads on each side for the toe adjustment and the tires fit great. Once I get it under weight I can set ride height and a proper IRS alignment, but things are lining up for now to proceed.
Thank you all again