I've started doing the LS1 front brake swap and I have noticed that the LS1 rotors have a slightly different bolt circle size than the metric hubs (stock hubs with the rotor cut off) I'm using. I'm assuming since this is a common swap that this isn't an issue, but I thought I would confirm this on here before I go crazy ordering parts. The metric bolt circle is 4.75" and the LS1 is 4.65", so the difference is 1/10". Therefore the clearance holes in the new LS1 rotor hats need to allow for that discrepancy or they will need to be clearanced a tiny bit. I'm thinking that even if the stud holes have to be clearance it isn't a big issue since the the hub registers between the two rotors are almost identical, which is what centers the rotor on the hub.

I've read that a better calipers than the LS1 ones to use with this swap are the C5 Corvette calipers and that it's a direct swap. Is this a direct swap using both the LS1 abutment brackets AND caliper adapter brackets, or do one of these brackets have to be for the C5 calipers?

Thanks for any input.

 

LS1, C5 and C6 dual piston calipers are physically interchangeable; late GTO and Caddy XLR/XLR-V calipers too. Each newer caliper is slightly better and stronger than the previous one, with C6/GTO/XLR/XLR-V being the best (LS1<C5<C6/GTO/XLR/XLR-V).

But while each caliper type will fit each conversion type, the spindle adapter brackets, pad abutment brackets and caliper guide pins must be specific to the conversion type. In your case, LS1. They're what properly locates the calipers over the rotors.

As for the LS1 rotor question, I believe GM used rotors that were originally designed for a different application. They fit and work because the holes are large enough to accommodate the bolt pattern, but they weren't designed for it.

 

Yes the LS1 rotors also fit the front drive montecarlo SS with a smaller pattern..one rotor fits two different platforms

 

That's interesting.