Hi, Can someone tell me what is the purpose of the two bolts in the center hub and if I can remove them for the installation of my spacers? See attached picture. Thank You in advance Image Unavailable, Please Login
On cars with cast iron brake disks, the bolts hold the disk assembly to the hub. The projections on the bolts help align the wheel to the hub to make installing the wheel bolts easier. As long as the disk assembly stays in place with the bolts removed, they can be eliminated. The wheel bolts will hold the disk assebly in place for normal operation.
They also keep the lugbolt holes in the rotor aligned with the lugbolt holes in the hub -- which is super-handy when wrestling with installing a large, heavy wheel. So when using a simple Type-1 spacer (to use Hill Engineering term) keeping that function in place somehow is a very good thing (because now you have three things to keep aligned when wrestling with installing the wheel); whereas, when using a Type-2 spacer it's not a big thing to just leave them out (as installing the spacer itself keeps the rotor aligned to the hub).
You can use a wheel assist stud. Wheel hanger, lug guide I can't think of the name of those things. They screw into the hub and thorough type 1 spacer and align stuff. Then you can hang the wheel off it as you hand place the other lug bolts. Then take out the wheel assist and put the last lug bolt in. You can buy them off Ebay in our metric sizes. OP make sure your lugbolts with spacers have enough threads to engage the hub. The minimum rule of thumb is say 12mm diameter bolt you want minimum 12mm of thread length into the hub. A type 2 spacer (AKA wheel spacer adapter) allows the OE bolt to be used and holds the rotor to hub position so you do not ever have to fumble with that. Using type 1 vs type 2 depends on how thick a spacer and application. Thin ones will be type 1. Thick spacers can be 1 or 2. 2 is best for streetcars and non-technical users. 1 is best on cars that see track time because we check lug torque after every session on track. You can't do that with T2 spacers because then you would have to take the wheel off to check which is a PITA. So on my 550M I use T2 spacers and my racecar Type 1. Image Unavailable, Please Login
When you take the small bolts out for spacers and then drive hard. You will find the lug bolts drag on the way out because the rotor has stopped against the lug bolt shank and the threads as the studs come out. I usually slightly loosed all five lugs and wiggle the wheel and that will ease up the drag on the studs and recenter the rotor holes around the stud.
Thank you for your detailed response, i purchased h&r 22mm for 599, and will use them on ff. I just hope it fits.
You can use two 8mm bolts instead of the pin bolt and regular bolt. Then you can machine a recess in the back side of the spacer to clear the bolt heads. I have also done this to keep the rotors from catching against the wheel bolts and making it difficult for them to come out.
