3rd gen front rotors

[Bullett801]

Hey guys, I am new to the forum, so glad to be here. I am currently restoring a 78 Monte Carlo and its been quite the challenge!! Even though I have been a mechanic for over 25 years!! So my current issue is the front rotors. I am trying to put a set from a 79 on the spindle of a 78. I was told it couldn't be done without some part changes, and I have made some good headway. I sleeved the 78 spindle ( my brother is a tool and die maker) with a custom sleeve, but now the bearing rides further out on the spindle and not allowing the castle nut and washer to fit on properly. I can't get the castle nut even close to the hole for the cotter pin to go through unless i put the castle nut on backwards, and then can barley get half the castle nut threaded on the spindle. I was thinking of machining the castle nut thinner, of trying to find a thinner one, or possibly drilling a new hole in the spindle for the cotter pin.

Have any of you tried to do this with success? If so any advice would be greatly appreciated. I know all about the difference in the spindles, so no need to waste time typing out why it won't work. The reason I am doing this is because for a 78 cross drilled and slotted rotors and super expensive, where for a 79 they are a dime a dozen. Thanks for any and all advice guys, and if I can help out in anyway please don't hesitate to ask.

 

[gnvair]

The 78 A body set up are a 1 year only spindle/rotor and wheel bearing combo. The design was updated with larger bearings that sat in a different spot on the spindle shaft in 79. I would locate a set of the 79-88 spindles and use the more readily available rotors and bearings. Just be aware that the studs were 7/16" std thread up to 1981 and 12mm metric 1982-up. The 78 model year A bodies had a lot of 1 year only items.

 

[ssn696]

1978 was a transition year. Steering column is also different. Consider parting a 1979-up for the column, steering box and spindles. I think the ball joints are the same. Or, upgrade to the 98-02 Blazer spindles. Bigger investment, though. Details on the Forum.

Would your brother like to make a set of sleeves so I can put 80s bearings and 8-lug rotors on my '49 one-ton Chevy panel truck? Lots of swap kits for the half ton stock front axle, but nothing I have found for the 3/4 and 1-tons.

 

[Bullett801]

1978 was a transition year. Steering column is also different. Consider parting a 1979-up for the column, steering box and spindles. I think the ball joints are the same. Or, upgrade to the 98-02 Blazer spindles. Bigger investment, though. Details on the Forum.

Would your brother like to make a set of sleeves so I can put 80s bearings and 8-lug rotors on my '49 one-ton Chevy panel truck? Lots of swap kits for the half ton stock front axle, but nothing I have found for the 3/4 and 1-tons.

I doubt he would to be honest with you. He is a pretty busy guy and it took him almost a month to make the ones that I have and needed some pretty precision measurements. But I will bet any machine shop would be willing to make them for you.

and Yes, I know about the blazer swap, and maybe in the future I will upgrade to that. I am determined to make this work though. When I do finally complete it I will make a video and post it for everyone to see. Thanks guys!! Im sure I willl have more hurdles to jump as the build goes on!

 

[Bullett801]

The 78 A body set up are a 1 year only spindle/rotor and wheel bearing combo. The design was updated with larger bearings that sat in a different spot on the spindle shaft in 79. I would locate a set of the 79-88 spindles and use the more readily available rotors and bearings. Just be aware that the studs were 7/16" std thread up to 1981 and 12mm metric 1982-up. The 78 model year A bodies had a lot of 1 year only items.

Thanks for the information. I have considered that and it is still an option, but I am determined to exhaust every possible way to make this work before I buy more parts. I am also aware of the blazer upgrade aswell.

 

[MC96]

Just go get some newer spindles, and be time and money ahead.

Any 2wd s10 / s10 blazer or any other G body.

 

[pontiacgp]

I would bit the bullet and follow what's been suggested...

 

[Bullett801]

Well, I managed to accomplish the impossible, and got it done with no out of pocket money, used all the proper torque specs and bearing adjustment methods described by GM, and only had to change one part. I went with a thinner washer between the outer bearing and castle nut, I made the grooves longer in the castle nut where the cotter pin goes after proper tightening and adjustments, and elongated the hole in the spindle. Keep in mind these adjustments to the castle nut, spindle hole and washer thickness were in the .000 range, but a little goes a long ways! So it can be done. Thanks for all the advice guys, but I had to put the front coil springs in with the body off the frame, no engine in it, nothing to weight down the frame. Even with the proper spring compressor tool it was sketchy at best, and did not want to do it again. That is the reason for doing this modification. Im sure when I get it all done, Ill be upgrading to those S-10 brakes soon. After all, we are always looking to for a reason to upgrade....right???

 

[pontiacgp]

Well, I managed to accomplish the impossible, and got it done with no out of pocket money, used all the proper torque specs and bearing adjustment methods described by GM, and only had to change one part. I went with a thinner washer between the outer bearing and castle nut, I made the grooves longer in the castle nut where the cotter pin goes after proper tightening and adjustments, and elongated the hole in the spindle. Keep in mind these adjustments to the castle nut, spindle hole and washer thickness were in the .000 range, but a little goes a long ways! So it can be done. Thanks for all the advice guys, but I had to put the front coil springs in with the body off the frame, no engine in it, nothing to weight down the frame. Even with the proper spring compressor tool it was sketchy at best, and did not want to do it again. That is the reason for doing this modification. Im sure when I get it all done, Ill be upgrading to those S-10 brakes soon. After all, we are always looking to for a reason to upgrade....right???

the "washer" between the outer bearing and castle nut has a key on it so it fits the keyway to prevent the rotation of the wheel on the left side to spin off. Years ago on the left side they had a left handed thread. The castle nut has no torque on it and the cotter pin just stops the castel nut from vibrating off or from decreasing the bearing play. If you are relying on the cotter pin to keep the rotor and wheel in place you should not be driving the vehicle.