521 front end conversion

[521Symmonds]

So, while I was wandering around junkyard I happened to find a guy trying to pull an engine out of a 85 pickup. Helped him out, and he gave me the whole front end out of it for free. I was wondering if the RWD set up mostly bolts into a 521. I'm unsure if the torsion bars had a matching spline design(trying to keep the original bars installed),and I'm trying to avoid tearing down the front end of my truck to find out. It would be nice to have ball joints and front disk brakes though.

[datzenmike]

Cut the frame behind the rear torsion bar mounts and graft it onto the 521 frame. None of the disc brake stuff will fit a king pin truck. Upper and lower control arms won't either. Torsion bars are all different lengths.

[wayno]

It can be done as I have done it, but it is not a bolt in, you have to do some modifications.

First you need to remove your lower control arm bushings if you want to do it right and replace them with 78+ Datsun 620 lower control arm bushings, then install the lower control arms, lower ball joint and a set of 620 tension rods with 620 tension rod bushings with the back half bushing cut in half as the 620 tension arm is slightly too long but the 720 tension rod will not work/fit.

Next you need another set of upper control arms other than the ones you are getting with the frontend, then you cut the arms in such a way that when you weld them together they will be three quarters of an inch longer than stock, when that is done you should also drill the 521 upper control arm mount bolt holes out and thread them to except the 720 upper control arm mount bolts, then you mount the left upper control arm on the right side and the right upper control arm on the left side, this will set the castor close to what it needs to be.

Now you can mount the 85 spindles, next you need to remove the right and left brake lines, cut the SAE ends off and put metric ends on them and re-double flare the ends of the brake lines, then you can connect the rubber brake lines to the new metric threaded hard lines.

Now you need to take apart the 521 brake master and remove the residual valve and put it back together, now you can bleed the brakes and it will stop the truck in a straight line, but it takes a lot of pressure, I drove mine like this for years, it stopped straight rather than doing a counter clockwise spin in an emergency stop.

As I said I drove it that way for years, I finally figured out how to make and mount a power brake booster, I then switched over to a dual circuit brake master cylinder, this was actually a great upgrade as it stopped way easier, it still was not great but it was way better than what it was.

After this I drove it for a while and then found a 1986 720 with a dump bed, so I gave up on the 521 frame which was falling apart as I also had power steering and that alone destroyed the 521 frame where I had mounted the 720 steering gear, I mounted the 521 cab onto the 86 720 frame and have never looked back, this truck stops better than it ever has even while pulling a trailer(trailer has electric brakes and has had them for years), putting that cab onto that 86 720 frame/chassis was the best conversion I ever made, but I have both the frame and cab titles in my name.

The only way to keep your 521 with all the numbers matching your title(frame and cab) is to cut the 720 frame right in back of the shock towers and graft them together there, that way you still have the part of the 521 frame with the VIN numbers on it, it's easier to just put the 521 cab onto the 720 frame, but my work truck has a flatbed which makes it easy.

I did put a 521 cab and box onto a 720 short frame, but there was a gap between the cab and the box(extra couple inches), I was able to mount the cab and box to make that gap a little less, but it was still a little larger gap than I liked.

I also use the 720 wiring harnesses in my 520/521 conversions that are for the 720 engine in that frame along with the steering columns, in the end it is a awful lot of work, but I believe it was worth the effort.

[Charlie69]

I followed Wayno's lead and put a 1980 720 2wd short bed chassis under my 1966 520.  I am also using the steering column with the turn signal and the ignition switches and wiring harness.I am also using the 720 heater/AC and the electric fuel pump.

 

I cut the bed mounts off of the 720 chassis and shortened them and moved them forward to lessen the cab to bed gap and also to align the bed height with the cab height.  I had to re drill the main and intermediate leaf spring leafs centering holes to center the axle in the 520 rear wheel well.  I also had to flip the centering bolt in the 1985 720 4x4 springs that I used to lower the rear of the truck 2" to match the drop from the Belltech 2" drop spindles in the front.  When going to the Belltech spindles you have to run a larger diameter wheel as the stock 14" wheels will rub on the lower control arms.

 

I retained the 520 gas tank and removed the right hand gas tank mounts from the 1980 720 chassis.  In removing the front gas tank mount I also removed the mount for the e brake cable in which I will remove the e brake mount from the tank mount and make a bracket and weld it back to the frame.

 

I will be going to rear disc brakes using the the Isuzu Trooper rear disc brake rotors and calipers and have made custom e brake cables.  I will be using Mike Klotz rear disc brake brackets that are still in the design phase of research and development.

 

The sky is the limit when customizing a Datsun truck or bar.

 

My 520 last year on the trailer to the SWDP 10th Annual Barbecue in Fontana California.

 

 

Shawn Drawdy's customized, removable hardtop, stretched cab, and shortened bed 521.

 

 

 

 

 

Shawn's 521 runs a 720 Z24 5 speed on the customized bagged 521 chassis.

[521Symmonds]

Thanks for the advice and a bit of direction. I'm assuming bebanni's custom upper arms would afford that adjustment Wayno was talking about. I'm in that "I wonder if I can make this work in a not extremely painful and complicated way" stage and I know everyone here has the knowledge and experience to save me from going down some dead end streets. Also, that's a sexy truck there Charlie!

[thisismatt]

Wouldn't touch beebani parts with a ten foot stick. But that's just me...

[mhub91]

51 minutes ago, thisismatt said:

Wouldn't touch beebani parts with a ten foot stick. But that's just me...

 

 

Not that I agree or disagree, but how come?

[thisismatt]

IMO, poor design/quality, some borderline scary products. Sends out products requiring additional work or correction just to use.

[wayno]

Save your money for something you cannot make, it is easy to lengthen a set of upper 720 control arms three quarters of and inch if you have 2 sets of them.

I suppose you could just cut your 720 upper control arms, spread them apart three quarters of an inch and bridge the gap with metal welded in there.

I think the hardest part is removing the 521 lower control arm bushings and installing the 620 control arm bushings made for a ball joint frontend, but I heard that some have just put washers in there to take up the slop.

I think the most import part is to drill out them 521 upper control arm mount bolt holes to except a larger bolt, them 521 mount bolts break as they are not strong enough, it sure does suck when you hit the brakes and the frontend falls out from under you because that upper control arm came loose because the bolts broke.

 

[Charlie69]

I would put the 720 a 720 chassis under it before I tried to make Beebani's arms work.  Datsun/Nissan spent a lot of time and money designing and producing the 720 chassis..  I used a 1980 720 chassis on my 66 520 and then I added Belltech 2" lowering spindles and 85 720 vented rotors and calipers.  I disd a re index on the torsion bars and this will get my front end down where I want it.

 

I would feel safer driving Any of Wayno's vehicles then driving a vehicle with Beebani's adjustable arms.  I have personally worked with a complete Beebani link setup, coil overs and adjustable control arms that a good friend of mine spent good hard earned dollars to buy.  His truck is sitting uncompleted and waiting for a local fabricator to design a working safe drive able setup.

 

Wayno does his work himself and what he does sometimes might not be the prettiest design but it works and it is safe.  Wayno drives and works his trucks.

[Paul hieb]

Anybody ever hear of a 280z front end fitting under a 520 truck. I want to do a disc brake conversion and someone said they heard people using a 280z front end. Control arms, hubs, spindles. Just curious if you all heard anything about it before I start looking for one in the junk yard. 

[]2eDeYe]

8 hours ago, Paul hieb said:

Anybody ever hear of a 280z front end fitting under a 520 truck. I want to do a disc brake conversion and someone said they heard people using a 280z front end. Control arms, hubs, spindles. Just curious if you all heard anything about it before I start looking for one in the junk yard. 

They are completely different. There are some options to use hardbody brakes but require custom adapters. 

[Crashtd420]

If you after just the disk upgrade Check out Silvermine...

 

https://www.silverminemotors.com/collections/datsun-620-520-521-310

 

I always recommend just the brackets and the buy the rest at your local autoparts store for the warranty...