I'm doing a 5 lug conversion and I have read many threads, but have not found an answer.

I will be using either mosler or 84-85 GSL SE 114.3 axles and have those drilled to 5 lug.

I don't have any parts in hand (I have an SA22 with drums)

my question is what is the diameter of the 84-85 GSL SE 114.3 pattern. the hub part where it the rotor goes on.

I am asking because I assume it's different from the 84 GSL with 4x110 bolt pattern axles, which is what I am starting with.......and I am trying to find rotors. but I need to know what the inside diameter of the rotor needs to be.

thanks.

 

update. I called centric to check the inside diameter of the 85 GSL SE rtors and they said it's 144.84



so is the hub diameter (where it goes into the rotor) on the GSL 4 x 110 the same as the GSL SE 4 x 114.3?

 

I just happen to have a pair of GSL-SE axles here as well as a digital mic and a couple free minutes.

I can't measure all the way across but it appears to be 154mm not 144mm.

ALSO - bear this in mind! The axles are shaped differently and locate things differently, so that measurement is irrelevant!

On the 12A axle, the axle face is flat and the wheel's pilot bore is part of the rotor or drum.

On the GSL-SE axle, the rotor is just a rotor and the pilot bore is part of the axle! Also, the rotor pilots off of the center like normal practice, and not the outside of the axle face like 12A.

The rotor pilot on the end of the axle is 66mm.

 

And just to clarify further, since I think I see what you may be trying to do now...

The difference in axle ends is deliberate on Mazda's part. The GSL-SE axles are longer outside of the bearing. This means that the rotor bells are different depths. GSL-SE rotors on GSL axles will not work since they will bottom out against the axle housing before the rotor contacts the axle end.

GSL-SE axles are the same as all other '84-85 axles from the bearing inward, so you can use GSL-SE axles in a GSL housing and vice-versa.

 

I will have the same rear axle set up as you, S3 disc axle housing with SE axles.
When the time comes and if I can afford them and they will drill them to 5x114.3, I plan on using the GSL-SE rotors with aluminum hats from KC Raceware
Then I'll be able to use the stock SE calipers and brackets.
I recall someone else getting some custom work done from them so I think they will work with you. I just hope it's not too expensive (I should get a discount for the props I give them on here).

Also, the S5 5 lug rotors fit nicely on the GSL-SE axles(with 3 of the lug bolts removed/drilled to 5 lug). But then you need the big brake kit or equivalent to mount the calipers and park brake cables.

 

There is a 10mm difference in the length of a GSL and a GSL/SE axle from the out side edge of the flange and axle bearing. The GSL axles are shorter

You can use FC turbo 5 lug rotors on GSL style axles but to do it right you have to do some machine work. Here is how I am doing it. https://www.rx7club.com/build-thread...-992966/page4/ - see post 86.

Note that I have redrilled the FC Turbo 5 lug rotors to 4 lug (4x114.3). I did this because there are more 15X8 4 lug wheels that fit my application than there are 5 lug wheels.

If I were doing a 5 lug swap I would use Moser GSL/SE 5 lug axles and FC Turbo rear rotors. They are 11" in diameter and they are vented. You will have to build adapters to fit the Turbo calipers to the FB rear end. See post 100 in the thread listed above.

There may be some bigger alternatives. For instance, look at 84-86 SVO Mustang rear rotors or rear rotors from 2005-201 mustangs. They have the same lug 5x114.3 pattern and are all vented. You would want to use the caliper that goes with the rotor in your setup.

By the way, Autozone gives pretty detailed specs on their rotors.