What Are My Front Brakes?

[Rekateer]

From the help of you guys and some local mechanics I've been able to pull apart my front end. I've made a discovery that the front end is disc brakes and not drums. I think someone would call this an upgrade but right now it's a headache because I can't figure out what it's from. I have some basic knowledge of cars, but I have no idea what's going on here. There were some bolts holding what I assume is the wheel hub to the rotor, but I think it's rusted on. I'm afraid to damage this piece of kit without understanding more about it. Any answers or idea of where to look for answers are appreciated!

 

 

[Rekateer]

I may be using some incorrect terminology with the rotor/hub. Forgive any mislabeling of the parts. I'm happy to take in new information on what is happening here and what all the parts are called.

[datzenmike]

The '78 and '79 had front disc brakes so either someone put a '74 cab on a '78-'79 frame or the '74 engine tag was swapped to make a '78-'79 truck look like a '74. Post a picture of the caliper to be sure.

 

The rotor can be turned down by a shop if not worn down too far. The minimum thickness is 0.413". If it can't be turned down then it must be replaced.

 

 

This does come apart right down the middle but very tight tolerances and age and rust is holding it. Strike the flange just to the left of those wheel studs and hit towards the right. A crack will form, keep tapping around and around and it will split apart to remove the rotor.. .

 

Below:

That seal needs to be pried out with a screw driver. If just replacing the seal you need go no further. Make sure you have new ones before doing this. The bearing will fall right out, clean in solvent, remove all the old grease and repack with new. If replacing the bearing there is an outer race you have to reach in from the other side with a brass drift and drive it outward towards where the seal was. The new one goes in from the seal side then pack the new bearing and fill the hub cavity with new grease and install the new seal. Grease the seal lips so it does not start dry.

[Rekateer]

Quote

The rotor can be turned down by a shop if not worn down too far. The minimum thickness is 0.413". If it can't be turned down then it must be replaced.

Good to know for the future

 

Quote

The '78 and '79 had front disc brakes so either someone put a '74 cab on a '78-'79 frame or the '74 engine tag was swapped to make a '78-'79 truck look like a '74. Post a picture of the caliper to be sure.

Here's the caliper. I actually was able to find the right size pads for the thing by saying it MAY be for a 78 instead of a 74. 

 

 

 

To be honest with you the innards of assembly looks good and the grease looks kinda recent compared to the rusty dusty majority of the truck. I'm just trying to confirm what it's from. 

 

While I'm here I also pulled the soft lines off and they're double female but everything I see online is male/female fittings for a '78 620. Why would this be?

 

[datzenmike]

Yup later '78 -'79 disc brakes and also used on the '80-'82 720 truck is looking for parts.

 

 

I don't think there can be female ends on the hard lines

[Rekateer]

So I'm dealing with a 78 or 79 620 and should look for those kinds of parts? 

 

6 minutes ago, datzenmike said:

 

I don't think there can be female ends on the hard lines

All the hard lines are male, that's not what I meant though. When I look for replacement flexible lines I see only male/female combos online, but what I pulled off the caliper is female/female m10x1.0. There's a place near me that apparently can make me custom flex line at my needed length, I'll go to them tomorrow and ask them about it.
Thank you DatzenGodMike

[datzenmike]

The L&R sides are the same Nissan part. #46214-89918 and again also used on the '80-'82 720. Take that number to an auto supply store and see if the can cross reference it.

[Rekateer]

Seeing the condition of the calipers, do you think they'll be ok as they are or should they also be replaced?

[datzenmike]

If not leaking or obvious damage to them they are probably ok. Easy enough to change later.

[Rekateer]

Other than being rusty as all get up, I don't SEE any real damage. I'll try to make them work as is then, and watch for leaks or lack of function. I found the proper hose line a little bit ago and I'll have them by Monday.

 

Again, I really appreciate the help and understanding of the users on this forum, and it's why I felt more confident in buying this truck beforehand than I would've had I not known this website existed.

[mklotz70]

you can get rebuild kits for the calipers on rockauto and ebay.  
Didn't the 620 calipers have a short hard line connected directly to them.....accounting for the female end on the rubber hose.

 

If you're going to spend some money on that front end, my suggestion would be to get spindles from a D21 Hardbody.... '86 and later.  You get better calipers, vented rotors.  You can use the hubs you have with the HB spindle.  I'd avoid any spindle earlier than that because of wheel fitment. The swap is just disconnecting the upper and lower ball joints, tierod end and brake hose from the hardline at the body.

Getting the rotors off....provided you're not going to reuse them(vid).  If you're going to have them turned, put the bolts back in and don't try to remove the rotors. 

 

 

More info about the brake differences for scrapyard reference.... 

http://www.bluehandsvideo.com/hub-info.html

 

If you haven't R&R'd bearings before, these vids should get you started....

 

 

More pics of your suspension might help solve the confusion over your frame/frontend.  There have been cases where guys have bolted the disc arms to the drum frame.  The shock tower on the drum trucks were inline with the frame. The towers on the disc trucks were at an angle.  I'm not that familiar with the 620 disc frames to recognize if the entire frame has been swapped.  

 

Good luck

 

 

 

[datzenmike]

The build date will be on a driver's door tag along with a car number I think.

 

The engine tag will have the car number on it. It's on the left inner fender near the coil.

 

If you wire brush the top of the frame in front of the right engine mount and near the alternator the car number will be stamped there. The frame and the engine tag should match.

 

 .

[Rekateer]

I swear I've looked where you're talking about by the alternator already for the number and didn't see anything obvious, but I'll look again, now that I'm in the weeds with this mystery machine. 

7 hours ago, mklotz70 said:

Didn't the 620 calipers have a short hard line connected directly to them.....accounting for the female end on the rubber hose.

They do, after the hose line there's about five inches of hard line.

 

8 hours ago, mklotz70 said:

If you're going to spend some money on that front end, my suggestion would be to get spindles from a D21 Hardbody.... '86 and later.

This is good information to have! It's a little funny that I can swap this because I used to own a D21 as my first vehicle. 

 

I'll look into the rebuild kit from rock auto and probably keep it on hand. I've already got so many parts anyway so what's a few more?

 

Thanks!

[Rekateer]

On 3/10/2024 at 1:28 AM, mklotz70 said:

The swap is just disconnecting the upper and lower ball joints, tierod end and brake hose from the hardline at the body.

Coming back to this, do you mean I only have to disconnect and reattach what I already have on the 620 to the new spindle points, or I need tie-rods and ball joints swapped along with the spindle? I'm having a little issue finding the spindle itself on rock auto for a D21. Obviously it exists, I'm just not sure where to find it under all the trees of options on the website.

[mklotz70]

ball joints and tie rods stay....just the spindle, caliper, rotor come from the '86 or later HB.  You can use your hub.  I would recommend just getting new rotors for the HB....by the time you pay for used rotors and have them turned, it cost about the same as new.  You're not going to find new spindles on rockauto.  If you want it lower, now would be the time to buy dropped spindles.

[Rekateer]

14 minutes ago, mklotz70 said:

You're not going to find new spindles on rockauto.  If you want it lower, now would be the time to buy dropped spindles.

I wondered because nothing was coming up and the only thing I see online is the dropped option. I don't necessarily WANT it lowered though. I'll look further into this as an option. Thanks!