Insane rx-7

iTrader: (1)

Hey guys,

Its time I do a write up on how I did my 4 piston front caliper conversion on my 1984 Rx-7. The reason I am writing this is because I used the second Gen four lug hubs to do it.

First thing I want to say is. This type of mod isn’t something you do in one day. Or expect it to be done in one day. Also it’s not something you can be cheap about. Do it right the first time and you will save money.

Step 1

You have to obtain second Gen front calipers and second Gen front hubs. (4 lug) Then you have to get the Respeed conversion kit from Billy’s site. This item is well worth the money. Billy himself is an awesome guy. He has awesome customer service. You need second Gen front rotors. These will be 5 lug rotors. The 4 lugs WILL NOT work. If you use these your car is unsafe. You can get second Gen brake lines if you want but I used my stock ones.

Step 2

Once you have acquired the items above. You can start modifying them to work together. This involves you having the rotors drilled at a machine shop to the 4 lug bolt pattern. You need only to drill 3 holes. This is the proper way to do it. You use one of the existing holes and drill the other 3 to the 4 lug pattern. I used junkyard rotors for this so I had to get them machined and drill. Also sometimes the aluminum hubs will fuse to the steel rotors. You have to get them pressed apart. You can try hammering on the studs but you will most likely have to get them pressed.

Step 3

Once you have the rotors machined and drilled, or if there new, just drilled. You need to get the hub machined down too let the rotor fit properly. When the 5 lug rotor slides onto the 4 lug hub there is a protrusion that sticks out from the rotor where it sits to the hat. This causes the wheel not to be flush up against the rotor and allowing the rotor to have “play” which causes safety issues and improper braking. This can be easily corrected by having a machine shop shave down the hat part that sticks out of the rotor so that the wheel bolts on flush. This material has no propose in keeping the hubs strength in tact. Machining it down won’t effect anything. In order for this to be done you have to punch out the studs. Either have them pressed out or use an air chisel and hold on for dear life. I DO NOT recommend you using a spacer behind the rotor to fix the gap between the hub hat and rotor. Having the hub machined is the safest way this can be done.

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Step 4

Once you have the hubs done and you can place the rotors on them properly. (No material sticking out the middle and rotors flush against hub) You can start looking at putting it on the car. First put the Respeed kit onto the car using the instructions given in the kit. Once that is bolted on you can slide the hub over the spindle. The inner bearing is on the back side of the hub and is held in with seals. The outside bearing is just placed on after the hub is set and you then can bolt the nut for the hub on and the castle nut with the pin. I suggest using new pins and not just reusing the old ones. DO NOT use the spacer that comes with the kit for spacing out the nut which holds the hub on. With the 4 lug hub it doesn’t allow the pin to sit properly. Now with the hub on place the rotor over the 4 lug hub and sit it properly. If you have a helper check for rotor clearance from the back side of the rotor and the Respeed kit. The clearance will be quite small. Although it should not touch. I have been running my car like this for a few months and I have had no problems with the clearance. Turn the wheel all the way in both directions and make sure your rotors don’t hit anything and you can make full turns.

Step 5

With the kit bolted on and the rotors and hubs on with no clearance issues. We can look at putting the calipers on. This now becomes an issue from how Billy’s kit is supposed to work. The hardware with Billy’s kit will not work for this. In order to space the calipers in the proper position you will have to get 8 more washers like the ones that come with the kit or ones that are close in size. Each side will need 3 washers for each bolt. You will also have to get 2 new bolts for each side. A total of 4. The bolt size is M12x1.5x45mm I believe. If you can’t get 45mm long bolts, like I couldn’t, what I did was get 50mm bolts and using a hacksaw I cut them to the length I needed. If you do this, make sure you get 2 nuts to go with it and thread both nuts onto the bolt. Thread them to where you want the cut to be. Open the one up so the hacksaw blade can slide in between the bolts and saw away. This will keep the saw in a straighter manner and after you finish the cut you can back the far bolt off and clean up the treads to allow it to thread into something. I suggest using something of grade 10 or higher. Because you have made them longer then what you get in the kit anything that’s above what the kit comes with should be bought. You can now take the calipers to the car and using the 3 washers place them between the spacer and the caliper and bolt the caliper on with the bolts you just modified. This is done for each bolt hole. A total of 6 washers and 2 bolts per side. Once again check for clearance from the bolt hole to the rotor back. This is to make sure your bolts aren’t sticking out and damaging the rotors. And also check clearance of the caliper now that it’s on.

Step 6

Once the caliper is on you can either place the second Gen lines on or use the first Gen lines. I used my first Gen lines because I didn’t have second Gen ones. If you use the first Gen lines you have to make sure you have clearance in the lines when you turn the wheel. My first Gen lines weren’t long enough to reach from the stock mounting spot. What I did is zip tied the line to the top of the stock mounting spot and it was enough to give me full turning clearance and suspension clearance. If you do this do not zip the rubber section of the line. Zip the metal section used to hold the line in the stock placement. With the lines on you can bleed the lines with a buddy and test the calipers to see if they are working correctly and have no leaks. Also when you have the lines off if you use a pair of vise grips and clamp the line lightly you can stop the fluid from draining from the system.

Step 7

With the lines, caliper, hubs, rotors attached and tested. You can bolt your wheel on. Your wheel has to be a 15” wheel I believe to bolt on and have clearance. Once the wheel is on, do another clearance check of all parts and the wheel. Doing this shouldn’t change your offsets. If you have wheels where a spacer is needed. Then you have to get new studs for your hub. I have a 1” spacer on my fronts and I needed to get 3 ¼” long studs to allow the spacer to slide on and have the exact stock amount of stud coming threw the wheel. I used ARP studs because there super strong and you don’t have to worry about damage. The other thing you could do is get an H&R spacer that bolts on and have your wheel bolt to that. I didn’t bother because it won’t be hub centric anyway and it’s another 400 bucks.

Step 8

I suggest once everything is bolted on take the car for a test run. Not to far from where you live and make sure its working properly and for the first run don’t be too hard on it. Drive around for a bit and go back and take everything off and retighten everything up. Check for leaks in the lines or any signs of clearance issues or rotor rubbing. If everything looks good drive around for another week and do it all again. I suggest that you check the breaks often and do a tightening check every week once it is complete.

Tips

Here are a few tips

Get all the parts first or have it all priced out before you start so you can decide if you want to spend the money

Find out if you can get the rotors machined. Some shops won’t do it.

Have the hubs machined and rotors fixed before you start. If you have all these things done before you start taking the car apart you won’t be out a car for a few weeks like I was.

DO NOT plan on making this a one day job. This should be done with patients and not at a quick pace; you do not want to miss anything.

Do a daily inspection and a weekly check on all bolts and parts used

I might have left some stuff out but this is a good start at what you would be looking at to do this job. Hope you guys find it informative and worth reading.

Insane rx-7

iTrader: (1)

Mistake in the tips part. It won't let me edit it I ment to say some shops won't drill the rotors. Any will machine it :O

Rico Suave

iTrader: (1)

i did it about a year and so ago also on mine.