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Glengemen

Front disks on a Pre-78 620 (Control Arm Method)

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Since I get asked every now and then how to end up with front disk brakes on my 77 620 here is the write up:)

 

First thing is gather up your parts. Listed from what truck to pillage.

 

D21 hardbody 2x4 (might be abe to use later 720 stuff with vented disks????)

 

Lower control arm

spindle and bearings

disk brake assy(rotor, caliper, rubber lines)

radius rods (you will need custom hardware to bolt this up)

master cyl. with dual front outlets

metal lines (I actually used S-13 hard lines)

ball joints

hubs (will need to modify to run the small bore wheels)

 

720 2x4 (I used an '85)

 

Upper control arm pivot pin

upper control arm bushings

 

620

 

Lower control arm bushings

shocks

steering linkage

 

Upper control arm is your custom part, mine was built by BEEBANI here on the forum. Heve him build it about 1/2" longer than mine

 

 

Take out your current suspention and put up a post here to see if anyone wants your old stuff.

 

You will probaby have to cut out your lower arms as the bushing likes to freeze in there and on mine there was no amount of WD-40 that was going to free them.

 

Install new lower arm bushings

 

install lower arm

 

assemble your upper arm, bushings, pivot, and balljoint

 

assemble your spindle brake and hub

 

Install upper arm install 2 1/8" alignment shims brtween the shock tower and the control arm

 

install spindle assy on lower arm, tighten 24mm? nut

 

Install spindle assy on upper arm

 

punch out the hole in your frame to accept the thicker HB radius arm

 

insert radius arm and find what you are going to use to bolt it up, and line up the first hole in the lower control arm. The second WILL NOT line up. This is due to increased track width.

 

using the now positioned radius rod as a jig drill though the lower arm with a 12mm drill bit and put your bolt through.

 

remove your master cylinder and front brake lines.

 

install your 2 front hard lines as they were in the doner.

 

slot the holes in the HB master all the way out so thy clear the booster studs.

 

gently place the master up to the brake rod sticking out of the booster, and measure how much needs to be trimmed off the brake rod so the master can be mounted. have the screw adjustment in the middle when you do this to allow for a slight error.

 

trim your brake rod up and remember to round your edges.

 

bench bleed your master

 

reinstall your rod and install the master

 

attach the 3 hard lines to the master

 

bleed your lines (it's OK to use the wife for this)

 

check to make sure your front brakes aren't locked up, if they are you need to bring your brake rod down a bit, if you have too much free play check your rear brake adjustment, then your brake rod lenth.

 

double check your work before putting your wheels on

 

I am not sure if there is a spcial bleed procedure if you still have the ride height valve installed ( I dont)

 

 

 

 

 

PICS WILL BE COMING

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Guest DatsuNoob

What parts would you need if you came across a 620 with front discs? There's one just like bleach's (well same year and beat up) down at Pull-a-Part. What parts would I need besides the obvious calipers and rotors?

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You'll also need the hubs, bearings, spindles, ball joints and I'd grab the control arms for good measure (although they will be too long for your truck, you'll want the bushings and whatnot)...then you have BEEBANI fab you up some new control arms and your set ;)

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What parts would you need if you came across a 620 with front discs? There's one just like bleach's (well same year and beat up) down at Pull-a-Part. What parts would I need besides the obvious calipers and rotors?

 

Really. I would go right past the 620 disk parts, as they are of the non vented variity. Look for vented rotor 720 and HB stuff. Regardless, the same mods have to be performed due to the disk brake truck's suspention geometry, hence the need for the fabed upper control arm,

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Do the Titans tuck with the custom upper control arm?

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If I were to bring my tortion bars all the way down the tires tuck in the front fenders. With a hardbody drop spindle it would tuck for sure.

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:)Most of you have seen these but I said I would put up some pics and here they are:

 

DatsunInterior032.jpg

 

DatsunInterior039.jpg

 

DatsunInterior016.jpg

 

DatsunInterior020.jpg

 

DatsunInterior015.jpg

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I know this is a really old post, but does this swap apply to the earlier 520 as well? I'm not completely familiar with the differences between the front end on the 520 vs the 521, but I'd love to get rid of the kingpins/add discs to my '67. Any help would be very much appreciated!

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I know this is a really old post, but does this swap apply to the earlier 520 as well? I'm not completely familiar with the differences between the front end on the 520 vs the 521, but I'd love to get rid of the kingpins/add discs to my '67. Any help would be very much appreciated!

 

Yes it does, and I have an updated design of the arms, it's currently in the new posts "upper control arms V2" or something like that is what it's called.

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Man!! This is a really nice write-up thanx dudes. I was wondering is it possible to get more pictures on this, pictures really help a lot for people like me who have limited experience working on cars,

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I am going to the yard to pull parts tomorrow! How much does it widen the track width?

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I measured it at 2.25" and i have seen posted by somebody else here that it was 2.5".

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anyone know of a way to just go ahead and use a 5 lug hub? i would really like to just go ahead and swap to disks AND to 5 lug all at the same time, hopefully.

 

let me know what you guys can come up with and ill do some research of my own.

 

***EDIT***

 

http://infamousnissan.com/forum/showthread.php?t=3104

 

this shows how a stock hardbody spindle can be machined to accept stock toyota hubs and rotors. :) 5 lug swap made easy. =D =D

 

 

let me know your thoughts and suggestions.

Edited by matwood

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I can't view pics right now....but it sounds kinda like the same thing I did for 808a6? Brian. I machined the mustang spindles to accept his 6 lug hardbody hubs.

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okay...I just went and read the thread....interesting. I've read/posted before that the bearings in both hubs are the same....so that raised the question of why they couldn't simply be mounted up. The way he has a 1/4" taken off the base of the spindle suggests that the Toy hub is 1/4" longer. If it were the same length as the nissan hub and the cut was made to get the rotor into position, then the outer bearing would be left hanging out on the end. I think the only way you're going to answer that question is to get a Toy hub to measure.

 

They also mentioned that the Toy seal diameter is smaller than the nissan and to have the base of the hub turned down at the same time it's shortened. You could compare the seal dimensions online to answer that question. Not running a seal would possibly explain why the conversions I've seen like this all say they destroy the bearings.

 

On the drum spindles on the older rigs, they all have a removeable collar at the base of the spindle......does the hardbody spindle? If so, that piece could simply be replaced with one that is shorter and has a smaller diameter.

 

 

On Brian's mustang II spindles, I turned the diameters down. I'm pretty sure the ball joint tapers match between the nissan and mustang spindles. If the wheel base and track width are really close between the two vehicles, I'm thinking the spindles could simply be swapped.

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Just went and found a pic of some dropped spindles....the seal collar is cast to the spindle...so that negates simply making a new collar to put on. It could easily be turned down at the same time it's shortened.

 

I couldn't find a pic of stock spindles....anyone have a pic. This conversion is intriguing, but not enough so that I'm going to go dig mine out of the shed in this cold!! :)

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I'm going to a couple junkyards today. In my neck of the sticks, there's very slim pickin. I'll be lucky if I find a hardbody, pathy, hilux, OR 4runner. If I do, I'm getting both front suspensions, complete, and also a rear end out of a toyota. Anyone know enough about these rear ends to suggest a ratio? It's gonna be behind a fully built L20B in my 521.

 

I'll let you guys know when I get back.

 

Beebani's UCA's.

Hardbody LCA's

Hardbody ball joints.

Hardbody spindle.

toyota hubs.

 

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Guest DatsuNoob

So I'm starting this on my truck real soon, got mostly all the stuff except for the UCA pivot rods. I've found out for myself the hard way that HB UCA's and pivot rods will not work out. Width difference of the mounting holes of the UCA pivots are different spacing. early ones are 19mm and later ones are 22? 24mm cant remember. Anyway, my question is which UCA pivot rod will match the factory holes(spacing and hole size) in the frame of a 620 and still have the same length as what's in there now?

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So I'm starting this on my truck real soon, got mostly all the stuff except for the UCA pivot rods. I've found out for myself the hard way that HB UCA's and pivot rods will not work out. Width difference of the mounting holes of the UCA pivots are different spacing. early ones are 19mm and later ones are 22? 24mm cant remember. Anyway, my question is which UCA pivot rod will match the factory holes(spacing and hole size) in the frame of a 620 and still have the same length as what's in there now?

 

The 720 pivot rod is what I used, it has the right spacing. I wish I had a good way to machine these and provide them with my uca's.

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Guest DatsuNoob

The 720 pivot rod is what I used, it has the right spacing. I wish I had a good way to machine these and provide them with my uca's.

 

Okay, surprisingly there was a shortage of 720's at the local yards last week. Guess I'll just wait it out and keep checking back. I saw a 720 4X4, but didnt pull them since they looked the same as D21. Thanks

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The late 720 used the same stuff as the hardbody. The early used the same as the 620. You want the middle years....but I don't recall which those are... '85ish?

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The late 720 used the same stuff as the hardbody. The early used the same as the 620. You want the middle years....but I don't recall which those are... '85ish?

 

Yeah, '85 is what I used. They came out with the hardbody in 86.5, so that's probably the last year for 720 that will work.

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So I'm starting this on my truck real soon, got mostly all the stuff except for the UCA pivot rods. I've found out for myself the hard way that HB UCA's and pivot rods will not work out. Width difference of the mounting holes of the UCA pivots are different spacing. early ones are 19mm and later ones are 22? 24mm cant remember. Anyway, my question is which UCA pivot rod will match the factory holes(spacing and hole size) in the frame of a 620 and still have the same length as what's in there now?

 

 

Noob, the pivot shafts that are needed are from the 78/79 620's or the early 720's. I thought the late 720 worked also, but others have said different. However, these shafts have the correct hole spacing for the drum brake frames, but the bolt hole diameter does not fit exactly. The drum 620 uses 12mm bolts and the disk frames use 14mm bolts, so the holes in the shafts are also 14mm. Have a spacer made if that little bit bothers you, its about your only option. Not sure i would weld on the shafts.

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