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Discussion Starter · #1 ·
Today I started the 12" upgrade on my 77. This is not a kit, I do not believe in using kits. The spindles were removed from a donor Oldsmobile 98. After checking bearing numbers and measuring every angle and part of the of both spindles it will be a bolt in swap. To be sure I installed the Nova spindles on the Olds and they bolted in with no problems.

The difference in the spindles is the area the caliper bolts on. It is moved out to allow the larger rotor to be installed.

The stock Nova calipers, pads and hoses can be used they are the same part numbers as the ones on the Olds.

The rotors from the donor cars can not be used because of the wheel bolt pattern. However the 88-92 Camaro with the performance option (1LE) uses a 12" rotor, it is even drilled an slotted from the factory GM #18016035. It uses the same wheel bearings and seal as the donor car, so it will also be a bolt on. The wheel studs will need changed to the stock 7/16" thread from the metric 12 mm. The wheel stud holes in the rotor will have to be opened up slightly in order to convert to 7/16 studs. A 35/64 drill bit will do the job.

So the upgrade is started and using all GM parts that are easily available any where in case an emergency repair is needed while on the Power Tour or cruising the mountains over by Littlerock, CA.

Here are some photos of the Oldsmobile and Nova spindles.

The donor spindle from a 79 Olds 98 that I received for free.



The Nova spindle installed on the Olds just to check for fit. I spent a lot of time cleaning and painting these and now they will not be used.



The Olds spindle weighs less than the Nova one. It is a difference I can feel, but have not measured yet. The bosses where the ball joints and tie rod end attach are the same thickness, the casting itself has less mass, but that could have been a weight savings change. Since the Olds is a lot heavier car I am not concerned about the strength of the spindles.

Not all B body cars have the correct spindle for this swap. They were manufactured with 2 different sizes of outer wheel bearings.

Here is a list of possible donor cars but check the size of the outer bearing to be sure you are getting the correct part. The correct spindle uses a .850" bearing and the smaller spindle uses a .750". This is the diameter of the inner race where it fits on the spindle. The 1LE rotor will not fit the smaller spindle.

Buick Full Size- Le Sabre Wagon / Electra Wagon 1977-1994
Cadillac Fleetwood and Deville 1977-1984 Brougham and Fleetwood 1985-1994
Chevy full size 1977-1996 Caprice, Impala, Belair, Biscayne
Olds Delta 88, Delta 88 Wagon and Olds 98 1977-1992
Pontiac Full Size Bonneville, Catalina, Grandville 1977-1986

I anticipate the total cost of this upgrade to be the difference between the cost of a pair new Nova rotors and that of the 1LE performance rotors which is less than $100. All the other parts replaced would have been purchased anyway to rebuild the stock brakes and the spindles were free.

I will post photos as the upgrade progresses.
With the Cadillac rear discs already installed (click here for that thread) and these front discs the Nova should stop very well :hurray:
 

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On the Chevy donor car it will need to be a fully optioned Caprice to bump the GVW up high enough to get the 12" Brakes. All 12" disc brakes use a 5 on 5 inch bolt pattern with 1/2' wheel studs instead of the smaller 5 on 4-3/4" with 7.16" studs used on lighter Chevys. Chevys that have the 12 brake package for sure are all cop cars (look for a certified speedo as a lot of agencies just bought a regular car as they were cheaper) and station wagons.

The wheel bearings on the B-body cars (Impalas and Olds 98's or Buick Electra's) are all heavier cars hence the bigger brakes. They also have bigger wheel bearings and tie rod ends on the spindle. The 1-LE Brake kit is an excellent choice as they use the bigger bearings have the 12 (or 13") rotor and bolt onto a B-body spindle.

I know that Speedway.com sells tie rod ends that will adapt to the bigger B-body spindles to the Camaro and Nova But I am interested in what Philip will find and make fit as well. Personally I lust after the Corvette steering knuckle with it's 13" to 15" brakes from either Bembo or PBR depending upon the year. They are much more of a challenge to adapt to the Nova front end without trying to splice in the whole front sub frame of the 'vette.

Big Dave
 

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Discussion Starter · #3 ·
The stock Nova tie rod ends fit perfect in these spindles and the ones on the Olds have the same size joint, just the arm part is longer. The heavier ones may be the cop car parts. I was told that police car package front pads are larger than the stock pads, same backing plate but with more material. I'll check it out and post my findings.
 

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Nope same caliper and pad as the 11" brakes I have three sets of brakes here at the house as I own two ex cop cars (one of which was issued brand new to my wife back in 1989 and has been in our possession ever since). I used slotted vented zinc clad 12" rotors from SSBC instead of the 1-LE because my police cars all use a 5 on 5 lug pattern. Though if you keep the old rotors you could re-drill the rotors using a 4-3/4 wheel as a drill template and install Moroso 3" long wheel studs in 7/16" to get that racer look and to be in compliance with NHRA safety rules which require an inch of wheel stud showing past the lug nut.

Big Dave
 

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Discussion Starter · #5 · (Edited)
The old rotors are grooved from the pads not being replaced soon enough. The SSBC rotors for the 1LE F body are $150 from Summit, if I can not get a better price from NAPA they will be the ones I use.
The pad number I was given is D62 and supposedly has more material on it than the stock pad.
 

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Great information!!

What year range caprice, etc. has the correct parts for this conversion?

I guess the 89 Caprice cop car had the correct bearing sizes then? Does the regular cop car have the same spindles?

So you use the calipers from the donor cars or do you use the X-body calipers? I know they use the same pads (52s), are they the same?
 

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question are you trying to improve the stopping power of the brakes..there is a quick simple up grade...Just use a 1976 amc gremlin with manual brakes with the brakes line on the fender side..the master cylinder bore size 1/8 inch smaller diameter and in turn make more line pressure and whick make more psi at the calipers and wheel cylinders ok.ive all ready done this trick on 3 vehicles of mine....go figure..works great..
 

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Discussion Starter · #11 ·
question are you trying to improve the stopping power of the brakes..there is a quick simple up grade...Just use a 1976 amc gremlin with manual brakes with the brakes line on the fender side..the master cylinder bore size 1/8 inch smaller diameter and in turn make more line pressure and whick make more psi at the calipers and wheel cylinders ok.ive all ready done this trick on 3 vehicles of mine....go figure..works great..
More PSI is not the answer to increase the stopping power of a vehicle. The increase in pressure may not be good for the rest of the system. Brake components are designed to work within specific limits, changing the pressure the system was designed for could cause a failure.

If you want to stop quicker with less brake fade and prevent over heating the rotors and pads an increase in the size or construction of the components is needed.
 

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Discussion Starter · #12 ·
Great information!!

What year range caprice, etc. has the correct parts for this conversion?

I guess the 89 Caprice cop car had the correct bearing sizes then? Does the regular cop car have the same spindles?

So you use the calipers from the donor cars or do you use the X-body calipers? I know they use the same pads (52s), are they the same?
First let me point out that this conversion will only work on the 75 - 79 Nova, the 70 - 81 Camaro and the 73 - 77 Chevelles.
IT WILL NOT WORK ON THE EARLIER NOVAS, CAMAROS OR CHEVELLES!!!

Not all of the 12" disc set ups use the same spindles. All will fit, but you will not be able to buy a rotor with the correct wheel bolt pattern. The calipers are the same but after 77 GM used a metric size banjo bolt to attach the brake hose to the caliper. I suggest just using the caliper that came with your car or a direct replacement.

To find the proper spindles the outer wheel bearing size is all that will need to be checked and is easy to do without even removing the wheel. Just pop off the cap, pull the cotter pin and unscrew the nut. Remove the washer and check the number on the bearing. The number should be LM12649 and have an inside diameter of .850". If it is LM11949 with the inside diameter of .750" the spindle will not work with the Camaro rotors.

Here is a photo of the bearings and the larger of the two will allow the use of the 1990 Camaro 1LE performance option rotors on the B body spindle.



BTW I went with the SSBC rotors, although NAPA listed them they were not available.

 

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Discussion Starter · #13 ·
New calipers are going to be installed. Here is a photo of the test fit. Stock Rally wheels rub on the face of the caliper and the 15" American Racing Torque Thrust D will fit after removing the stick on weights and changing to clip on rim weights. It is a really tight fit with the 12" brakes, with the stock 11" there would be no issues.



Oh I also installed new control arms :D
 

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The rotors from the donor cars can not be used because of the wheel bolt pattern. However the 88-92 Camaro with the performance option (1LE) uses a 12" rotor, it is even drilled an slotted from the factory GM #18016035.
The interchange from 18016035 to a NAPA number is NBO 4885994. About $70 retail. I haven't verified fitment, but the listed diameter is correct. As I post this, NAPA has none, back-ordered to "the factory"; which may be a Virus Originating in the Wuhan Lab (VOWL-19) thing, or it may be that they're just plain discontinued.

Or O'Reilly number BBR-5994RGS. About $105.

i notice that in both cases, "5994" is part of the part number. I bet you could go to any other parts store, ask for a "5994" brake rotor, and get the equivalent.

Diameter is listed as "11.850" on one site, "11.87", or "11.9" on other sites.

The Olds spindle weighs less than the Nova one. It is a difference I can feel, but have not measured yet. The bosses where the ball joints and tie rod end attach are the same thickness, the casting itself has less mass, but that could have been a weight savings change. Since the Olds is a lot heavier car I am not concerned about the strength of the spindles.
The "spindle" is the round-section machined-steel piece that presses into the iron casting. The spindle is what the bearings ride on. The whole assembly is more-properly called a "Steering Knuckle".

The steering knuckle was re-designed in...1978, perhaps. Weight was shaved off, and--supposedly--strength was improved, all through the miracle of "Computer Aided Design".
 

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These are BMR for a 2nd gen F body. UMI also makes a nice set with more built in caster
So......I have been combing many places for info on suspension for 4th Gen Novas and have heard that the suspension is effectively the same as the 70-81 F-body. If true that's great because you could just about build a 2nd Gen F-body from scratch out of aftermarket parts!!

What I don't get though is that if this is universally true for front suspension, why don't all these manufacturers say their parts also fit 75-79 X-bodies?
 
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