720 front Suspension on a 620

[orangie]

Does anybody know if a complete front 720 suspension wll fit on to a 620, including power steering box? This would include the 720 tie rods as well.

[datzenmike]

The suspension parts I don't know. Maybe but not a truck made after oct. '82. For the steering box you would also have to swap the complete steering 720 column as well. The 620 is a one piece column and box. How will you mount a power steering pump???? on an L series engine???

[orangie]

The pump can be electric worst case and the steering  shaft can be an after market Borgensen shaft if need be.  This truck has an SR20det so it is really tight.  Still trying to figure out the picture thing with photo bucket, that thing crap it hangs up all the time.

[jesusno2]

Personally I would graph on the 720 frame horns onto the 620 to get the full benefit of a 720 front suspension especially a king pin 620.

[orangie]

I'll find a pic and take a look. I thought they were the same. I have beebani's shock towers for coilovers, but I need to check the height and distance for the control arms to make sure the front suspension geometry won't get scewed up doing a control arm swap.

[wayno]

Find another photo hosting site other than photolame.

Is you 620 a 4 drum truck?

If it is, forget it, I have went down this road, there are to many issues long term.

The first issue you will run into is that unless the upper control arm brackets you have can be extended 3/4 of an inch, you will not be able to align it, the 620/720 balljoint lower control arms(LCAs) are longer than the kingpin LCAs, but you can shorten the LCAs if you can fabricate stuff, I actually made some 720 drop arms, the first set I made I narrowed about an half inch on each side, the second set I narrowed 1 1/2 inches on each side.

 

 

 

When you do stuff like this you are basically starting over.

This is what happened to me recently, I added power steering to my 521 several years ago now, I had to fix the frame yesterday after many years of abuse, unless you do it correctly, these frames were never made for power steering.

The bolt on the right side of the photo below is the front power steering gear mount bolt, the bolt with the big washer is the back steering gear bolt shared with the front idler arm mount bolt, I have an idler arm on the driverside mounted in the stock position of the stock 521 steering gear, I will show you why.

This is the custom centerlink I had fabricated, it has a tierod connection on the passenger side.

 

This is the 720 steering gear mounted on the outside of the 521 frame.

The clearances are tight, but I had a frame to mock this up on before tearing into my actual driver.

 

As you can see, I have done a lot of fabricating over the years I have owned this truck, I am hoping by next year this cab will be on a 720 frame, as I am tired of the monthly repairs and other issues I have been having with this frame making it into something it was never designed to be, but I did not know what I was doing back when I did all this, so I have the attitude that I was learning and am giving myself a break.

[orangie]

I do have a 4 drum car. I was thinking about putting the 720 control arms and spindle as well. As for rust on the car, there is very little. This is an original Arizona truck. Hmmm, maybe its easier to shell out money for a narrow set of custom wheels and run skiiny tires up front.

[ol' 320]

I had the guy I bought my 320 from install a 720 clip and rebuilt 720 frnt suspension before I bought the truck. I drove it before and after... no comparison. There is a thread on here about it. 

 

http://community.ratsun.net/topic/34698-320-balljoint-conversion 

[jesusno2]

I'll find a pic and take a look. I thought they were the same. I have beebani's shock towers for coilovers, but I need to check the height and distance for the control arms to make sure the front suspension geometry won't get scewed up doing a control arm swap.

Yea it will. Their not good to begin with. Even the stock 720 geometry is bad. It's better than a king pin truck, but still has positive camber issues. The 720 has about 1/2 degree of castor angle give or take. ya gotta remember these trucks were Cheap, and engineered to haul garbage to the dump and drive easy down the road. Shameless plug but if ya look at my 521 build were trying to fix those issues with a set of good adjustable upper arms and roll center anti-dive adjustment on a king pin truck. their never gonna handle like a F1 car but with some work and trail and error hopefully we can get one to handle like a more modern car would.

[orangie]

Jesusno2, thanks for the reply.  If it handles similar to the 720, I'll be happy.  This truck is going to be for cruising, some light truck duty and  maybe some occasional drag strip fun.  It wouldn't be my choice of cars for handling anyway.  I just like the way the truck looks.

[erichwaslike]

i have a full kingpin/drum to balljoint/disk conversion in the works, one truck with it but i didnt keep track of cost. when i do the next one im jigging everythign so it can be duplicated. it will be modified arms that use 620 or 720 spindles(your choice)

 

arms will cost about 300, all you supply is bushings, balljoints and spindles. all the hard fabrication work will be done. will also be building drop lowers. the drop setup will be for slammed trucks and run abour 400 maybe a lil more

[orangie]

erichwaslike, got any pics of the front control arms?  I might be interested.

[erichwaslike]

the drop arms not yet, the standards look like a stock arm. they arent changed much but they are. everythign is a modified stock arm so when ppl look at it it blends in and no one will be the wiser its not the as delivered setup. the drop arms will be done next month hopefully as they will be going on my personal truck. it rides at an inch of the bump stop and i plan to make em clear the stop a bit but not a cut up stock arm, it will be a full fabricated arm from scratch.

[jesusno2]

Dropped lower arms are pointless from a geometry stand point. They do the same thing as turning your torsion bars down.

[erichwaslike]

no they dont, i only have an inch to where the bump stops should be. i need a lil more travel so it will allow more up travel at the same ride height....

[jesusno2]

geometry wise, they move both ball joints up altering roll center and instant center angles. same as turning torsion bars down. they may give your more clearance from the bump stop I agree. dropped spindles are far batter as the dont alter any geometry only down fall to a drop spindle i can tell is a touch of bumpsteer i notice. 

[wayno]

Dropped lower arms are pointless from a geometry stand point. They do the same thing as turning your torsion bars down.

 

Let us face it, if you lower any of these torsion bar datsuns, the geometry is screwed up, either you live with the ride/handling, or you start over, and yes the easiest way to lower a stock "disc brake" frame without issues is to use drop spindles, if you start adding custom arms and such, you are starting over.

 

Drop arms(LCAs) have an advantage, they allow the use of stock 14 inch wheels, drop spindles do not have this option unless your vehicle came with 15 inch wheels stock to start with, at least I believe this statement to be correct.

[jesusno2]

Let us face it, if you lower any of these torsion bar datsuns, the geometry is screwed up, either you live with the ride/handling, or you start over, and yes the easiest way to lower a stock "disc brake" frame without issues is to use drop spindles, if you start adding custom arms and such, you are starting over.

 

Drop arms(LCAs) have an advantage, they allow the use of stock 14 inch wheels, drop spindles do not have this option unless your vehicle came with 15 inch wheels stock to start with, at least I believe this statement to be correc

My point, why make a bad system worse. I mean they look cool, air bagged trucks look cool, but worthless in my opinion. Everybody likes to add all this horsepower to these trucks, or what have you, and make it drive like a shopping cart with wobbly wheel lol. and in reality theirs prolly 10% of datsun/nissan guys that use stock 14 inch wheels. I lowered my 720 with blocks, spindles and a touch of T bar drop so i am being a bit of a hipocrite, but i am in the process of a panhard bar to correct my rear roll center and the front i can correct some with a bigger sway bar. But even 720 front suspension is only slightly better. You still lack caster adjustment, and stock arms are positive camber city. Anyone can walk up to a datsun truck and push down on the left or right corner of the fender and you can physically watch the front tire tip out at the top. emagine whats going on in a corner. your tire is only contacting the ground with maybe (Depending on how bad the front end is) with 25% of the tire. I personally like quite a bit of caster angle also makes the car/truck drive nice at highway speed the steering wheel comes bad to center fast etc. Sorry for the long post.

[wayno]

We have gotten a little off track here, what was asked here is if the early 720/620 disc brake assemblies can be put on a early drum brake 620 truck, the short answer is no, it will not bolt on to your truck and function properly.

Can it be made to fit, the long answer is yes, if you throw enough time and money at something, you can make it work, I was able to make it work, but if I was to do it again, I would do certain things differently from the start.

I have changed the way I upgrade, I use 720 frames now, but my builds are more involved than just upgrading front brakes, I want all the bells and whistles now.

 

I can talk all night about how to drop a torsion bar datsun truck, I have learned a lot on here about all the different ways, and all the little tricks to get another inch, or in some instances half an inch, but if it don't drive decently, I don't want to drive it.

[orangie]

I got my ebay lower/upper control arms and a spindle last night.  I'll take more measurements this weekend, but it looks like it will fit and the changes are small.  The upper control arms is the same length and looks like it will bolt right in.  The lower looks like it is about an inch longer, but the difference is made up with the lower connection of the spindle going further out an inch.  The only fabrication I will have to do is add about a quarter inch spacer on the inside of the control arms, unless the bushings take up that much space.

 

I want to be confident this can be made to work before I commit to cutting the innter fender to get the 720 power steering box mounted.  Also the mount on the frame is going to take some slight mods to accept the 720 box.  The 620 mount sticks out a little so the power steering box will not mount flush.

[wayno]

I got my ebay lower/upper control arms and a spindle last night.  I'll take more measurements this weekend, but it looks like it will fit and the changes are small.  The upper control arms is the same length and looks like it will bolt right in.  The lower looks like it is about an inch longer, but the difference is made up with the lower connection of the spindle going further out an inch.  The only fabrication I will have to do is add about a quarter inch spacer on the inside of the control arms, unless the bushings take up that much space.

 

I want to be confident this can be made to work before I commit to cutting the innter fender to get the 720 power steering box mounted.  Also the mount on the frame is going to take some slight mods to accept the 720 box.  The 620 mount sticks out a little so the power steering box will not mount flush.

 

The 720 steering gear mounts on the outside of the frame, so what steering hardware are you going to use?

If you are using the 720 hardware, you will have to use all of it, even the idler arm, I have never measured it to see if they are the same width, if they are not, it's not going to work without some major modifications.

You buy your arms from someone on here, or on ebay?

[orangie]

The plan was to use as much of the steering and suspension as possible.  Custom stuff or fabricating is possible, but it also gets more expensive.  Yes, the control arms and spindle are ebay so I hope the are the correct 720 parts.  I think Johnny Cash had a song about a car that was made from parts from all different kinds of cars and years.

[orangie]

http://img819.imageshack.us/img819/1015/datsun620007.jpg  Testing this web host out.  This is with the SR engine next to the steering box.

[orangie]

Uploaded with ImageShack.us.  Testing this image host.  This is the SR and stock steering box. 

[orangie]

 

There is hardly any room for accessories with even the manual steering box.  Still playing with the 720 suspension fitting on the 620.  I put an angle finder on the stock suspension and ran it through it's travel.  It measured about 89 degrees from almost lower to upper end stop. Keep in the mind this was just for reference since I don't think the truck is actually on level ground.  So far the 720 mocked up the on truck measures about 87 degrees across full upper to lower position, so it's only about a degree difference and that tilting in towards the truck. 

 

My next hangup is getting the coilovers to fit.  This may take some modying of the upper control arms.