Steering, Suspension, & Brakes

Robbie, The .79-.81 is so close you could use the hat and rotor on the rear with no problem. For the front use a short hat behind the hub like stock. The only problem is the hats are all 5 lug. You could have a shop tig a ring over it and drill to your hub pattern. You would have to know somebody because if you have welding done on brakes or suspension parts, they either won't because of liability or the cost goes way up. That's why I comb through stock part interchange lists. The 86-88 Toyota Cressida rotor I'm using for the MGB kit is 10 3/4" diameter and 22mm thick vented like the RX7. I think you will find the GM rears way too big. I plan on using 86-87 Acura Legend front sedan rotor,10.4" diameter and 20mm thick vented like the RX7 for the rear kit. Perfect match. You could just drill your hub pattern between the 4 existing holes for the front and drill your wheel pattern between the 4 holes in the rear and slip on. Not knowing the hub diameter or axle diameter of your Alpine, may or may not have to be turned down to fit. You can get fancy slotted and drilled rotors also. On the master if you have excessive pedal travel move up to 7/8", again the same as RX7 Turbo II.



Edited 5 time(s). Last edit at 02/10/2011 08:29AM by mgb260.

Jim, where do you find stock part interchange lists?

I found a place that sold blank hats about a year ago when I was doing the rears. I can't remember if I saw it online or if I asked Wilwood if they can sell me one before the holes were drilled. I'll try to see if I can dig it up. I don't have power brakes so I'm worried about the pedal stiffness going up to 7/8 or 15/16 and not having a booster.

[www.summitracing.com]
Summit sells the undrilled wilwood hats, but a year ago I found a different company that made them and ost less.

Rob, not Robbie, Boy this is getting confusing. On Rockauto.com you can click on the blue stock# and it will tell you what years and models parts fit,very handy. Also Centric website for rotor dimensions. Robbie, I had no idea you could buy the blank hats,remember to have the offset so you have a minimum of 1/4" to 3/8"steel to 1/2" for aluminum caliper adapter. The 7/8" master is what the RX7 used. You don't need a booster. If too big you would get a hard pedal. You can try yours and if too much pedal travel go up then.



Edited 1 time(s). Last edit at 02/10/2011 11:17PM by mgb260.

I'd like to know that other source for hats, I may need a pair. Aluminum?

JB

I don't remember what they were made of but j know they had blanks in all sizes. My computer crashed a few months ago, so looking through all my bookmarks last night, it seems I lost the site. I think I found them by searching for undrilled rotor hats or something along those lines.

Most race suppliers sell undrilled hats in both aluminum and spun steel versions. The big guys like Pit Stop, Pegasus, and HRP World mostly sell Wilwood but look around at some of the more specialized outfits that cater to road racers. That said, the spun steel Wilwood hats come in an endless variety of hole spacings and off sets and at about $40-$45 each are an attractive option to aluminum and almost as light.

David, Your car looks great! Unusual mix of old and new style. I think it would look even better if the rockers flared out to meet the fenders. Or side pipes like a Cobra. You might need wheel spacers to fill the fenders. How are the brakes coming?

Jim,

Thanks for the props on the B. Going with side exhaust similar to LeMans cars so it will exit right in front of the rear wheel. Thought about the rocker flares and still may go that way or may save it for something to do after I'm on the road. I have a set of 1" spacers on hand (from previous project) that I can use if I need to move the front and rear tracks.

On the brake project, I have everything on hand (finally) and a complete write up (less photos) but have been giving my time to the B's bodywork while the weather has been warm (in the 30's for last 2 weekends). Funny how my build seems to revolve around the weather. The brake work is inside stuff (small work are in the basement) so I try and save it for when it's too cold to work in the garage. The new kerosene heater is a welcome addition and has really extended my ability to be in the garage but even it has limitations when the temps drop to zero.

Wow, it's almost scary how well the dimensions worked out. I still need to make spacers for the calipers and drill bolt circles but the caliper mounts are going to be dead simple it looks like. The hats that came with the rotors are 3.4" from the flange to the backside According to my calculations the new calipers will need to mount 3/8" (.363") inboard of the spindle mounting lugs. Couldn't get any simpler than that. I'll have to double check again of course but it looks right. They will also have to mount 1" outboard to accommodate the larger diameter. There is 2-3/8" on the front side so plenty of clearance there.

These rotors are a floating design mounted with about a dozen beefy fasteners. There is a floating block anchored by each SHCS that fits into a rotor slot. Weight is about 10 lbs with the hat. I dunno, NASCAR or something I guess. Extreme overkill for sure. Bill, over on MGE is going to have a cow when I tell him.

JB

Oh. Except for the tie rod ends. Knew it was too easy, the rotor is sitting 1/2" farther inboard this way. So a shallower hat, and close clearance on the wheels, or bend the steering arms inward. Hmmm.... decisions, decisions. Maybe a little of both and 1" thick aluminum mount adapters. After I remove the dust shields maybe I can get by with a 3" hat.

Those darn tie rod ends. I ran into that several times trying stock part alternatives. I also thought , boy this is easy! That's what makes this fun, the challenge! I have a healthy respect for the factory engineers and still I have problems.

Heim ends instead of tie rod ends.

Nah, that doesn't help any.

JB

FWIW, I just completed aluminum, sleeve/spacer/adapter, to fit series II RX 7 hub on to Mustang II spindle. Using Ford outer bearing in Mazda outer cup. Welded beads on inner RX 7 cup, to drive it out,(no punch-out ports). Adapter holds the inner ford cup and moves it .700" away from outer bearing. Adapter also holds Mustang II inner seal.Yes, I could have bought a Wilwood brake conversion kit, for a lot more $'s, for less braking. What's the fun in that ? Dem's da brakes, roverman.

Art, That's cool! Are you going to use the RX7 calipers with a hat and 11 3/4" .81"rotor set up? You need about 2 1/2" from face of rotor to face of hub that wheel bolts on. Plus 2 .035 stainless shims. See pictures on 4 lug Cressida rotor thread on MGB page.

Jim N. and clan, I got convinced .81" rotors would warp, on front. I went 1.25"thick x 11.75", bout a lb. more, $31 ea. and Wilwood 4 pots @ $126 ea. .81" x 11.75 with RX 7 pots, should work fine on rear.Car weight approx 2,800. Approx 500-600 hp. will NEED enough whoa. Price for "cryo" is $35./ea.. I'm thinkin, "radial" holes in the hats for additional cooling ? Wouldn't ceramic or pyrolitic graphite,( 200/1 thermal flow ratio), work better for shims, less thermal transfer ? Cheers, roverman.



Edited 1 time(s). Last edit at 03/18/2011 04:12PM by roverman.

"I don't see any problem using shims for .81 rotors.RX7 stock used 22mm(.88)rotor.Maybe they were thinking about going to 24mm and thats why the wider slot. "

Sorry to dig up this old thread, but Jim, you were right about the 24mm sizing.

[www.racingbrake.com]

And from this site:
The rotor thickness has been increased to 24mm from OE 22mm for increased thermal capacity. Read more here.

1.Some brake pad manufacturers have increased their pad thickness (ie. EBC) therefore our rotor will not fit. Please verify your pad thickness is below 16mm.
2.Remove any factory brake shims from the pads before installation so that the rotor will fit in the caliper.

Robbie, Thanks for verifying that. I thought it was strange that Toyota used a 22 mm thick rotor and Mazda RX7 slot was so much wider and pads always come with shims. My junkyard calipers had 3 shims on each side. One stainless(anti-squeal) and two plain steel about .030. I saw your thread on the Sunbeam Alpine board on your 4 link. Are you doing the RX7 brakes also? This thread was about to be resurrected anyway as David Townsend has done a comprehensive article on the Mustang hub/Intrepid rotor set up.

This weekend I just got started on my 4 link. I got the tires, brakes, gas tank, leaf springs and perch mounts removed. The rest of my
Parts should be in this week so I can start going in the back together direction with it. While I have my car up I was looking at what it would take to swap the rears for now since I have them off already. I think I could reuse my brackets that the gm calipers are on and just cut them a little shorter and drill 2 new holes in them. If everything else goes smoothly with the suspension I'll probably do that while it's apart. If it drags on I'll just put it back together as is and do it this winter.