320 Brake Drum Replacements

[duckapin]

Hello 320ers,

 

I had just started a thread in Parts Wanted, but now I think I could use some help to determine which parts I should actually want, so I veered into this specialized area. I have made a good faith effort to search this site before starting this thread, but I did not  find the information I am looking for.

 

I am in need of two rear brake drums for my 1964 L320.

 

I was under the previous impression that 320 and 520 drums were identical, but now I see that they have different part numbers: 40206-32204 and 40206-14900 respectively. So they are not identical, but I still hold the unattributed presumption that they are interchangeable. As for later year models 521 and 620's drums, I had the impression that they were by dimension incompatible. 

 

I'd like to hear from members who have successfully used later year models' drums on 320s. It seems 520 drums will take much more effort for me to obtain at the moment, so I am especially interested to know if anybody on here has used the 521 drums and can tell me for from experience that they work in this application. And incidentally, I really like the idea of upgrading to disks, but it's really not in the budget for the foreseeable future.

 

Thanks for reading! Please respond if you can help.

[wayno]

You need to keep in mind that if there is any difference at all in the drums, they will have a different part number.

One of the differences is the 320 and 520 have these screws that hold the drum onto the axle ends, I don't know when this part was deleted, but any drum without this is going to have a different part number such as the 521 drum, even if it is the same.

Another thing I have not looked into is if the backing plates, if they are different shaped, then the drums might be different shaped also, I just went out and looked at 3 different styles in my stock pile, with 3 slightly different shaped drums.

Question, can 521 backing plates be used on a 320 axle housing, or can even 620 or 720 backing plates be used on a 320 axle housing, and use the more modern available datsun parts?

I think that if the 320 axle back plate mount surface on the axle housing measurement is the same as the 520/521/620/720, then they are all likely interchangeable.

I have a 320 axle out back complete, but the reason I did not chime in on your parts wanted inquiry, is because the drums will not move, I quite likely could ruin them just trying to get them off.

[KFunk740]

I just bought mine at Autozone, for $30 I think.  I think they were for a 521.  Seem to be working fine.

http://www.autozone.com/autozone/parts/1969-Nissan-Datsun-521/Brake-Drum-Rear/_/N-iw976Z8knp2

[420n620]

got a few rear drums that are from a L320. 

 

Let us know which way you want to go. used or new

[Conner]

When I was researching parts I found this very helpful thread from Zenon: 

http://community.ratsun.net/topic/3907-320-brakes-overhaul/

 

He bought Beck Arnley #080-0307 for the fronts and #083-0307 for the rears.  Those were for a 520.  When I went shopping for parts a few months back B/A appeared to have discontinued the #083s (the rears) and they since appear to have discontinued the #080s (the fronts), because neither part appears in their online catalog anymore.  And they no longer list a drum in their catalog for 320, 520, 521, 620s, or 720s.  B/A is not the only vendor, though.  Rockauto lists some different drums for the 520s, 521s, and 620s. 

 

I guess there are two questions.  (1) can the 320 run drums from a 520, 521, 620, and/or 720?  (2) are the 320 front and rear drums different/unique parts or are they interchangeable? 

 

From my 320 FSM the brake drum specs (complete with broken English) are as follows: 

Inner diameter, both front & rear:  254mm (10")

Degree of real circle of drum:  less than .05mm

Amendment limited of dittoed degree:  0.20mm

Allowable limit of inner diameter 0.80 x 2mm

So it seems like the 320 front and rear drums are the same size. 

 

I also have a Haynes manual for a 510 and PL521 1968-1973.  In the brakes section the specs for the 521 drum are as follows: 

Front drum diameter:  10" (254mm)

Out of round (max):  .0008" (.02mm)

Maximum reconditioned diameter:  10.059" (255.5mm)

Rear drum:  Specifications similar to those for front drum brakes. 

So it seems like the 521 front and rear drums are interchangeable and at least have the same inner diameter as the 320 drums. 

 

For a 1967 520 Rockauto lists a single drum, Centric #12242005 ($20.89 each) and cross references that with the 521s, 620s, and 720s up through 1981.  That listing includes a nice pic with dimensions and specs for the Centric drum which are: 

Outer diameter:  288mm

Height:  59.5mm

Norm diameter:  254mm (this is the same 10" as the 320 drums above)

Max diameter:  255.5mm

Friction surface:  48.58mm

Hub reg:  90.00mm

Bolt size:  13mm

Bolt circle:  6 x 139.7mm

Weight:  12 lbs. 

This drum also seems to have the same inner diameter as the 320 drums and the same drums are used front and back. 

 

Other than the inner diameter and bolt pattern and whether a drum will physically go onto the 320 hub, I don't know what else needs to be the same, in terms of specs, for these later drums to interchange onto a 320. 

 

I bought a set of the B/A 520 front drums (B/A 080-0307) and was planning to try those on all four corners but can't say they worked because I haven't done my brakes yet. 

 

I'm looking forward to hearing what others have done. 

[Stoffregen Motorsports]

I'm 99% sure that the 320 front and rear drums are if not the same, at least interchangeable.

[Conner]

I just looked in the Centric catalog online (http://centric.cataloglookup.com/), and they do list the 1964 and 1965 320 as an application, and the drum for both front and rear is part number 122.42005 (same part Rockauto lists for the 521 onward).  Cenetric also lists the same part number for a 1969 521, front and rear, and for a 1981 720 for those produced to 6/81.  After 6/81 they list a different drum for the 720.  I also spot checked a 1972 620 and it lists the same part number front and rear.  All the same drum. 

 

So at least this Centric drum is available and listed as a fit for the 320.  And it provides some indication that these drums should be somewhat interchangeable between the early and later trucks. 

[wayno]

Here are what I have at the moment.

320 drum, the center is sunk in slightly

Here is the 320 mount screw hole, 520s also had these.

521 drum

1978-79 620 rearend drum from a mobile home, same drum as any 620, slightly sunk in the center.

1980 720 rear drum, came from a 4X4, slightly sunk in the center.

1986 720 rear drum, as you can see it is not sunk in, but sticks out slightly, this happened when the automatic rear brake adjusters appeared.

All the drums except the 320 and 86 720 drums had these markings.

This is a 1985-86 dually rearend drum.

All the drums from the early 720 back to the 320 appeared to look basically the same.

[Conner]

Thanks for the pics! 

[Stoffregen Motorsports]

This is a 1985-86 dually rearend drum.

Wow, the dually was a full float axle. That would be a fun conversion.

 

Is the spindle welded on or bolted on?

[wayno]

Wow, the dually was a full float axle. That would be a fun conversion.

 

Is the spindle welded on or bolted on?

 

Spindle?

 

I just put that photo in because it was there.

 

EDIT

I guess I have only had it apart once to do the brakes.

 

I hope this answers your question.

[Stoffregen Motorsports]

The full float hub is just like a front wheel hub. It has two bearings inside, either packed in grease or fed with oil from the diff. The bearings ride on a spindle and are held in place and adjusted with a pair of nuts...just like a front hub.

 

Lots of full float spindles are a welded on part of the axle, but some of them bolt on. If those ones bolt on, chances are that they use the same bolt pattern as do the backing plates of a non full float setup, opening up a world of mix-match opportunities.

 

I bet they are wleded on though.

[wayno]

I guess I never really thought about what that was called, but your right, it is a spindle.

The spindle is a big tube with a giant nut holding the drum in position, and the axle goes threw the spindle into the side gears and bolts onto the end of the drum/hub with six bolts.

It's been years since I had one apart, I seem to be able to even wear these rearends out in my work truck though.

I have no reason at this time to tear into this rearend, I am looking for a new carrier case(the part that holds the spiders and ring gear), as the shaft that goes threw the spider gears has ovaled its own hole in the carrier case, since it is ruined, I thought about welding the shaft in its original position, but I found another rear axle to replace it instead, so this one sits awaiting another dually project.

I have asked here on Ratsun before, but is the later 720 4wd axle carrier the same as this dually carrier, the housing looks the same.

[Stoffregen Motorsports]

Well Shaggy, there's only one way to find out.

[duckapin]

Thanks for all the responses, guys. I think I'll order the oldest model-fitting drums available from my local parts place and just give'r. I'll let you guys know how it goes in case anybody wants to know. 

[KFunk740]

Thanks for all the responses, guys. I think I'll order the oldest model-fitting drums available from my local parts place and just give'r. I'll let you guys know how it goes in case anybody wants to know. 

Yup, thats what I did.  If the wrong drum shows up, then you just take it back.  But you shouldn't have a problem. 

[bigman420]

How bout the wheel cylinders for the front and the back?? Are they the same anybody have good party number handy

[duckapin]

As for rear wheel cylinders: I have twice bought a pair of '65-'66 520 wheel cylinders on ebay from seller: vintageimportsinc.com1999.

 

Mine were NRC brand, made in Japan, in the box, but the part number is illegible on either box. The seller worked with me on adding a second part to the single part listed and combined shipping for me. The wheel cylinders worked perfectly for my '63 L320. 

 

Incidentally, I ended up ordering drums for a 1969 521 from Autozone. They look a bit different and some of the dimensions don't correspond to the 320 drums, but after assembly, they seem like they'll work just fine. The axle I'm working on is still out of the truck, but I'll follow up when it's all back together.

[bigman420]

Are front the same or what that's one one i need to replace

[KFunk740]

Fronts and rears seem to be interchangeable for drums, wheel cylinders are different though.  I replaced both front wheel cylinders with some that I bought on rockauto.com just by looking up the oldest truck they had them listed for (520 or 521).  I did the same for the rear, and got what appear to be correct.  I haven't installed the rears yet.  One of those jobs that keeps getting put off... 

[bigman420]

Well previous owner did the rears...so i just need to do the fronts...guess i need to get on rock auto and get some:) thanx....everything i saw on Ebay or whatever only listed rears

[KFunk740]

Yeah, looks like RockAuto has them for the 521, and so does Autozone.  They look like the proper ones.  The fronts only have one piston in them that goes out, and the rears have pistons on both sides.  No idea why.... 

[bigman420]

They look pretty cheap too

[bigman420]

Yay for non expensive parts for once