Spindles and Disk Brakes for a 77 620?

[frenchsquared]

First off, Hello.
New to Datsun's but not cars or minitrucks. I have a nice collection of toys and Im a pretty good at doing all my own work.

Looking forward to getting to know this community. Picket this 1977 up about two weeks ago. Dropped it 3" added new wheels and I am about to install a weber and header. It has 94,000 original miles. Runs ok but the I think the carb leaks from every seal possible.

 

 

I have spent a while reading in google and it seems 720 parts will fit the 620. However, I did not find any clear info on what parts. 

I figure I need upper controls, lower control arms, after market spindles, rotors and calipers. 

 

But is there other stuff needed as well? Tie rods work?

 

I think I saw that the shock mounts wont work. They need relocated can someone confirm this? 

 

Long term plan is to bag the truck. Is it better to get a disk brake upgrade for a king pin truck, keep the king pin set up and bag it as is.
That will get the truck lower or is it better to get the 720 parts and bag it on those?

 

Short term is the get it 2" lower and drivable for a while. I am also working on a B2200 and I want to finish it before tearing into this one. 

 

If there is a thread on all this, please send me a link. I really have been searching in google the last few days and didn't find anything clear. 

 

Thanks. 

[datzenmike]

.

[wayno]

Welcome :)

 

You cannot just bolt on disc brakes to a drum brake truck, if it was possible everyone would do it and there would be threads about it, it can be done but it takes fabrication skills and extra suspension parts.

I have done it to my 1971 Datsun 521, but it took years to get it dialed in, and there is no dedicated thread about it from me as I did it before this forum existed, I have wrote about it but I cannot recall any of the threads now.

I for the most part discourage doing this as I have had the upper control arm bolts break several times, but again I did this to a 521 not a 620.

There are kits out there like Mike K's that bolt onto to your kingpin front end, Mike's use the later 720 vented rotor/calipers, they work correctly without having to fiddle with them, I believe he makes/has made them for the 620.

[Farmer]

Multiple post in the brake section. Good luck

[Charlie69]

Be carefull of what you read on the internet.  720s have the steering box & idler arms on the outside of the frame rail. 620s are on the inside of the frame rail.  720s are disc brake fronts as are the 78 & 79 620s. 84 720s went to vented disc brakes & different calipers.

[frenchsquared]

Welcome :)

 

You cannot just bolt on disc brakes to a drum brake truck, if it was possible everyone would do it and there would be threads about it.

 

Yes you can. Wilwood makes a kit. Very easy and well priced. It just bolts on. Im not running out and buying it because it is for the kingpin trucks and I am not sure I am keeping that. As for fab skills if I have to I will change the entire front suspension. This truck will lay on the ground and it will have disk brakes. Just deciding the best way to it. Im sure I can make an S10 front end fit under it. 

[frenchsquared]

Be carefull of what you read on the internet.  720s have the steering box & idler arms on the outside of the frame rail. 620s are on the inside of the frame rail.  720s are disc brake fronts as are the 78 & 79 620s. 84 720s went to vented disc brakes & different calipers.

 

Thats why I am asking here, figured if it actually works then someone here will have done it. 

[wayno]

Yes you can. Wilwood makes a kit. Very easy and well priced. It just bolts on. Im not running out and buying it because it is for the kingpin trucks and I am not sure I am keeping that. As for fab skills if I have to I will change the entire front suspension. This truck will lay on the ground and it will have disk brakes. Just deciding the best way to it. Im sure I can make an S10 front end fit under it. 

 

OK that may be true, but you were asking about what 720 parts that will bolt onto a 620 kingpin truck, you said,

 

Quote "I have spent a while reading in google and it seems 720 parts will fit the 620. However, I did not find any clear info on what parts" End Quote

 

You can do it with a combination of ball joint 620 LCA/tension rods, lengthened 720 upper control arms(how I did it) and any Datsun truck ball joint disc brake assembly made till 1986, I am even using the 1990 Nissan hardbody V6 dual piston caliper setup on my 1971 Datsun 521 truck, everything between the upper and lower control arms bolts right in once the control arms are done/installed, but them control arms are not bolt in, they need modifications, and it can be done with the stock shock towers you have, but stuff needs to be modified/changed.

[thisismatt]

Yes you can. Wilwood makes a kit. Very easy and well priced. It just bolts on. Im not running out and buying it because it is for the kingpin trucks and I am not sure I am keeping that. As for fab skills if I have to I will change the entire front suspension. This truck will lay on the ground and it will have disk brakes. Just deciding the best way to it. Im sure I can make an S10 front end fit under it. 

 

Wilwood doesn't make anything for a 620.  Other people make caliper adapter brackets that fit wilwoods to 620 kingpin spindles.  You're still stuck with kingpins and bushings that are becoming more scarce by the day.  No one makes a bees knees kit to convert kingpin to balljoint...please don't mention beebani crap.  

[2wheel-lee]

Yes you can. Wilwood makes a kit. Very easy and well priced. It just bolts on. Im not running out and buying it because it is for the kingpin trucks and I am not sure I am keeping that. As for fab skills if I have to I will change the entire front suspension. This truck will lay on the ground and it will have disk brakes. Just deciding the best way to it. Im sure I can make an S10 front end fit under it. 

 

Just to clarify, Wilwood does not make a kit for the 620. There are other people making kits using Wilwood calipers. 

 

You'd really butcher a 620 to fit S10 suspension?

[datzenmike]

Geez S10? Nothing will line up. Frame rails, steering, body mounts, suspension, engine mounts, oil pan clearance.... Beter to swap a 620 body to an S10.

 

Cut the front from an Oct '82 or newer 720 and graft onto the 620.

[BEEBANI]

Why not mention it Matt?  Do tell. 

 

I have many many very happy customers out there who have done the swap with great results.  Upper and lower arms bolt right up, little bit of welding to do for the lowers.  Allows you to use spindles, hubs, brakes, etc. from '86-'98 hardbody pickups.  Keeps the stock track width and has full adjustability for camber and caster.  Perfect for bags.  I even make bag brackets and external shock mounts to go with the bags.

[frenchsquared]

Whats wrong with beebani? 

He is one of them that I have looked into. 

 

No, I wont use an S10 but I will either bag it on the kingpin or I will just use a complete front end from something. Haven't done enough research to define the something. 

 

Im leaning towards a bolt on brake upgrade and keeping the kingpin know that I know it will lay from on them. 

[datzenmike]

King pins are shit even except maybe when new and working right. Takes a shop who know what they are doing and have the reamer and measuring equipment to do it right. Any idiot can change a few ball joints.

[2wheel-lee]

I've driven a number of 620s with king pins over the year and I never thought there was anything wrong with them. Yeah, the trucks drive like antiquated crap, but it's what we're used to and expect from them compared to newer designs. 

 

And then I started to rebuild them on my current truck. What a bunch of crap they and the pivots are! 

Disassemble then reassemble them and let us know what you think. 

 

Though I put mine back together just fine, I wasn't going to keep them. I got a set of Beebani's upper and lower control arms and a set of Hardbody drop spindles. I also installed a set of QA1 coilovers to lower it even further. Oh man...such an improvement in ride and steering over those king pins. 

 

If you have the means, dump that stock crap. 

 

Oh, and bags are for groceries and taking out the trash.

 

Just a fun jab from an old school mini trucker. ;) 

[Rick P]

Hi, I’m attempting to resurrect this old post because I’m considering purchasing a neighbor’s 73 620 truck. I once had a very bad (scary) experience driving a vehicle with drum brakes in the front and swore I’d never do it again. So, I’m wondering if in the years that have passed since this thread was active, has this product come on the market as a viable, no fabrication, bolt-on conversion? It is assumed I will purchase 15” wheels to fit if the truck doesn’t have them already.

 

https://www.silverminemotors.com/products/1964-1977-datsun-620-520-521-310-front-brake-upgrade-kit

[Ooph!]

I've heard of the Silvermine kit but have not used it

[datzenmike]

You must be rich. These trucks need the 4 brakes adjusted at minimum every 6 months or it will pull to one side and/or the pedal becomes too soft. Otherwise they stop the same. Disc mean no maintenance or adjustments ever, just pad replacement. Drum can often feel grabby on damp mornings.

[Rick P]

No, I’m not rich, but I’ve been waiting for this guy to sell this truck to me for many years, and luckily he is being very reasonable on the price considering it’s in decent shape. I’ve been saving for something like this so I have the cash to buy it, but I will have to part ways with my 1980 Harley FXWG that haven’t ridden in many years to pay for the brake upgrade and the other maintenance work the truck needs. So no, not rich, but determined.

[Stoffregen Motorsports]

19 minutes ago, Rick P said:

No, I’m not rich, but I’ve been waiting for this guy to sell this truck to me for many years, and luckily he is being very reasonable on the price considering it’s in decent shape. I’ve been saving for something like this so I have the cash to buy it, but I will have to part ways with my 1980 Harley FXWG that haven’t ridden in many years to pay for the brake upgrade and the other maintenance work the truck needs. So no, not rich, but determined.

Somewhere on this site someone did a writeup on installing that kit. Or maybe it was just part of their thread.
 

I understand why you'd want disc brakes. Drums can overheat and then you have absolutely nothing. I've been there too.

 

$800 bucks for a comprehensive kit is by no means expensive.

[Ooph!]

I know Mklotz no longer sells kits but is Beebani still in business?

[thisismatt]

9 hours ago, Ooph! said:

I know Mklotz no longer sells kits but is Beebani still in business?

Hope not 😆

[Rick P]

22 hours ago, Stoffregen Motorsports said:

Somewhere on this site someone did a writeup on installing that kit. Or maybe it was just part of their thread.

$800 bucks for a comprehensive kit is by no means expensive.

I did some searching on this site and found quite a few conversations about conversions where Silvermine products were used or discussed for use, and most were positive responses/experiences, with one or two calling the kit crap. I did not find the write up you referred to but that’s OK, I think I found enough information to determine that the kit is safe, doesn’t require fabrication to install, and is somewhat straightforward to install, which is all I was after in that regard.

 

In the process of doing the research I learned a couple of things that are concerning though, the manufacturer themselves state that stock wheels will not clear the calipers, and there are two reviews from customers who bought just the brackets to save money by rounding up OEM parts to complete the install, they were both happy with the brackets but both regretted going that path and recommended buying the complete kit to avoid headaches. I’m fine with buying a complete kit but one of the threads on this site said that the calipers that came with the kit required 1” spacers for the wheels to clear the calipers. I’m not interested in using spacers, but apparently there are calipers that don’t stick out as far and with the right caliper and wheel combo, no spacer is needed. The truck does not have factory wheels, it has 14” aluminum slotted wheels, so there is a chance they will fit over the calipers without spacers, but it’s a crapshoot at best, I may end up having to chase down the right wheel with enough offset, and I don’t want the wheels sticking out of the wheel well. So, there’s a bit of uncertainty as to how straightforward this would be from start to finish.

 

On 8/25/2024 at 5:57 AM, datzenmike said:

Drum can often feel grabby on damp mornings.

That grabby feel is exactly why I’m researching the conversion, my El Camino had drums up front from the factory, and it grabbed one damp morning and nearly put me into a spin. Lucky for me, later model disc brakes bolted right on, I swore to never drive on drums in the front ever again. The owner of the truck said he’s owned the truck for twenty years and never felt it grab. For some reason that statement doesn’t raise my comfort level all that much.

[Stoffregen Motorsports]

1 hour ago, Rick P said:

The owner of the truck said he’s owned the truck for twenty years and never felt it grab.

Of all the vehicles I have ever owned, only two of them have had drum brakes that grab, and for no apparent reason. Both of them had completely stock brakes with no mods, all new parts correctly installed, and for some reason, when it's damp or snowy or the first braking of the morning, the brakes grab suddenly. My 77 Cherokee which I drive almost daily, has this problem still. I've never been able to figure it out.

 

The wheel spacer thing, I think I remember that conversation and I believe that guy was trying to use stock steel wheels.

[Ooph!]

Just for thought, 18 wheeler's or Semi trucks use drum brakes, it would be rare to find one with disk brakes.

In my experience, my 73 620 still has drum brakes I used to daily drive it until 1987, I never felt a lack of stopping power in the front it was the need to get under it every oil change to adjust brakes that was the problem because they never put automatic adjusters on them. If the steering linkage and suspension are kept in good condition there shouldn't be any problems.