720 Suspension Mods Question

[620slodat]

I have been reading the 720 part of the forum, and so far I haven't found the information I have been looking for. This is for a 1982 720 front suspension, and I am looking at possibly changing the torsion bars to coil overs. I'm not interested in lowering, unless there will be enough fuel savings to offset the cost. There have been a few threads about coil overs, but nothing that tells about the possibility. I'm assuming that this can be done, but none of the threads I have read about this have been completed.

 

From appearances the center opening of the UCA has the width, but possibly not the depth when the suspension is at it's extreme lowest position. It's not a forgone conclusion that this is a mod that I will do, just that I need complete information just to make an informed decision. The only reason I am considering the mod is because I am swapping in a diesel motor and not having a torsion bar there would make it much easier to run a large down pipe through that area (planning ahead for a future turbo). I have been told that an exhaust can be run through there with the torsion bar in place, but it looks to me like it isn't an easy thing to do. Information please, and thanks in advance.

 

OOooopppps, this is in the 620 forum, not the 720 forum. If it would make any difference mods can move this.

Edited January 22, 2019 by 620slodat

[datzenmike]

The '82 suspension is almost identical to the '78-'79 620 so what ever has been done to a 620 will transfer to the early 720 as well.

 

wayno has a turbo diesel on either a 521 or a 720 and both have torsion bars. Having a custom down pipe made is cheaper than converting to a coil spring although I'm sure someone did this... maybe Mrbigtankers? Again on a 521? If you couldn't find a finished one it's because it's too difficult or expensive.

[Charlie69]

The upper control arms are the same from 1978 to I believe 1990 on 2wd trucks.  I have change the spindle on my 1980 chassis to a 1985 spindle to get the vented rotors and larger calipers.

 

Mike Klotz makes custom upper & lower control arms check out the Bory 521 build thread.

Edited January 24, 2019 by Charlie69

[Lockleaf]

http://www.infamousnissan.com/forum/showthread.php?t=23303

[wayno]

There is plenty of room to do this, I have just in the past few weeks changed over to another turbocharger in my 720 and I piped it the way it is in the photos below.

 

I am in the process of piping the other one I took out in case I don't like the one in it now.

 

You have the links to them threads I sent you via email on NWD and the diesel forums.

[620slodat]

Thank you all who replied. Like I said, this is an exploratory thread to help me make a decision, and all the replies (current and future) will do so.

 

Knowing for sure that the 78 and up 620 front suspension, and into the early years of the 720, are basically the same helps with decisions. It stuck in the back of my mind from the reading I did that they were (too many facts for this simple mind), but knowing for sure is a big help. The extra costs are the big thing now. I will have to rebuild the non-vented rotor front brakes anyway, so the extra expense between the two will be the deciding factor. I do know that upgrading to the vented rotor will mean the cost of 85 and up spindles as probably the only extra cost. Now I need to decide if the extra cost of drop spindles over used factory style spindles is actually needed. I'm not interested in dropping, unless the extra cost for dropping compared to fuel savings will be enough of a factor. 

 

Wayno, you already mentioned your view on this, and now I need to explore your avenue. My first thoughts are about space involved. I know that you did this to a 521, and that a 620 engine bay may very well be slightly different. The pictures of just the motor and transmission with the exhaust in place you already posted are helpful, but if you have any pics of the engine bay in this area will also help. Something else that will be a big help is if you have pics of where the downpipe goes around the torsion bar and dimensional space to nearby objects. I realize that if you don't already have the pics that time for doing so may be short, so if you don't have the time now it is OK.

 

Something that will make a big difference with the exhaust is that the e-brake cable cable comes through the firewall and, because of the down turn it has, comes within 1/4 inch away from where the exhaust exits from the manifold. One thing (less expensive maybe) that will help tremendously is moving the e-brake handle to the transmission tunnel. This will open up that area of the firewall, and just maybe I can use the current 620 cable with the "new" long wheelbase 720 frame I got from you. The big thing will be can I find an e-brake handle that is reasonably easy to put on the transmission tunnel, and what does it need to hook up the e-brake cable.

 

From his web site I don't think Mike K has anything in stock for a replacement UCA, and am not sure if he plans to make any more in the near future. However, I live very close to Beebani. Maybe within 10 miles, so I need to get together with him and see what he has available for doing a coilover and how much I would spend setting up for this.

 

Lockleaf, thank you for that link. I read the whole thread, and it really helped with knowing more about Beebani and coilovers. Now, what are the costs for the parts and are they compatible with my pocketbook. Decisions decisions.

Edited January 24, 2019 by 620slodat

[wayno]

OK, let's talk about the e-brake first, the 720 had a few different types of e-brake handle assemblies, one had the cable pointed down at a 45 degree angle likely like your 620 does, I do not use this type, I use the e-brake handle assemblies that point straight forward towards the radiator in my diesels as I recall, I also used the longer front e-brake cables that allow me to route them where I want them rather than trying to work with what I have with a shorter cable.

Now I realize that you have a 620, but I stick the 720 e-brake handle assemblies in my 521 trucks, so you can likely put them in your 620 also.

Here is the e-brake handle assembly in my 1980 720 turbodiesel sticking straight out the firewall.

Here is another angle, you can see the rubber filled oval hole below it, that is where it comes out on the type that is angled down.

Here is a 720 e-brake handle assembly in my 521 work truck with an LZ23(L block), it is the type that sticks down as there is no starter or exhaust pipe directly in the way.

 My 1969 Datsun kingcab turbodiesel truck has the type sticking straight forward as you can see in the photo below, you can also see the rubber piece covering the hole for the original e-brake cable below that bolt/nut holding the 720 e-brake assembly in my 521.

 

It's too hard to get a photo of the down pipe routing, but from the starter back it's basically the same as stock routing.

 

Now I understand that there is not as much room in the 620 engine compartment as there is in the 720 engine compartment, and my turbo in the 521 is mounted on the side of the manifold in that truck which allowed me to route the exhaust out in the stock 521/720 place, and the photos of my turbo mock ups are for 720 trucks, but I suspect your 620 has more room in the engine compartment than my 521 has also.

 

The exhaust is piped out between the torsion bar and the transmission on all my builds, I make sure that when I have my exhausts built/made, I have a flange put in to be able to remove that piece of exhaust pipe so I can remove the transmission without having to cut anything.

 

Personally I would wait on the front brakes and use what I sent with you, they will stop the truck just fine, just not so good if you were coming out of a pass with a shitload of firewood in the back of your truck, they may get hot in that situation and not work so good, I had non-vented rotor disc brakes for a long time in my work truck, but I used to haul massive amounts of weight in that truck, not so much anymore.

If you wait and keep looking you could likely find a good deal on brakes out of a 1985+ Nissan 720 and they will bolt right in, you could also keep checking out the wrecking yards, seems like you should be able to get something good for way less than new parts will cost you.

 

Edited January 24, 2019 by wayno

[620slodat]

Thank you for the reply Wayno. I had not realized that Datsun made anything other than the angled e-brake cable. I will definitely check that out. I am going to put bucket seats in place of the stock bench, so IF I go with the e-brake handle on the transmission/driveline hump I will have the space. When Dad was still alive I occasionally rode in the 620, and I never liked the bench seat, very uncomfortable. And now with the back and hip problems I'm dealing with a very comfortable seat is a no brainer. The 05 Buick Century we have makes me hurt when I'm in it for more than about 30 minutes because of the seats. I already have a pair of 1995 Pathfinder seats stored away hoping that they will be comfortable for me. 

 

Since I have the 3/4 ton Chevy I will be using that for any heavy hauling/travel trailer towing I need to do. Most of the time it will be setting, especially since I can't afford to use the travel trailer very often. So, the only "work" the Datsun will see is just occasionally carrying tools, light duty hauling, and daily driver use that is conducive to putting it together with mileage as the focus. Also, I'm hoping that the mileage will be good enough, and the creature comforts I'm planning to add will induce my wife to be willing to take the occasional longer trip in it, She is dealing with fibromyalgia and needs the creature comforts.

 

Because of the expense of the changes I am thinking of I will most likely have to go with stock items. This includes the brakes. But, I need the information (including costs) so I can make informed decisions. The biggest reason I decided to use the 720 frame was because of the front suspension. To have room for the creature comforts that need to be attached to the motor the steering gear box needed to be on the outside of the frame. I was already looking into the possibility of changing the steering to the outside of the frame on the 620. It involved a lot of work (which I'm not afraid of and have the time for), then you offered the 720 frame and it was a no brainer for me. Your pictures and information are crucial to these decisions, and I really do appreciate and thank you for them.

 

Something I thought of today involves turbo placement. Every turbo I have ever seen had the intake air facing the front of the vehicle and the exhaust into the turbo behind that, towards the firewall, with the exhaust out of the turbo at the very back. What if the turbo was turned 180* from that. Would that make it any easier to install in this situation? I haven't had time yet to even look at the 620 to see if it is even feasible. The reason I'm bringing this up is because I want/need input about this. I want you, or anybody else, to give me your ideas about this, good or bad.

 

I know that this thread has gone beyond questions about the front suspension, but everything so far still involves the 620 and how it will be set up, so it is OK with me.

 

 

Edited January 25, 2019 by 620slodat

[wayno]

What I would do if I were you is go to the wrecking yards and sit in a bunch of different seats and find ones that work for you.

As for the turbocharger exhaust being pointed towards the front, that creates a couple issues, first the exhaust would likely have to either go under the oil pan cross member, that is the lowest(closest to the ground) part under the truck, below that area is the steering gear, I like power steering and that adds extra lines in the way and the steering column goes from the steering gear up towards the firewall, there just isn't any room in that area.

The way I did the last couple of exhaust routings  was I had the exhaust from the stock outlet go forward and stay away from the block to the turbo base inlet pointed down, what this does is it gives me a route to the get the turbo exhaust out by coming out of the turbo down and a little forward in towards the block, then once I get to the pipe going from the exhaust manifold to the turbo I start routing it out under the steering column and beside the starter, by this time I am now under the steering column and between the frame and starter, if I get too low in this area I hit the frame section supporting the front suspension stuff, so i basically have to parallel the pipe above it as soon as possible, point it down after passing the starter and then making a turn between the torsion bar and the transmission case, the exhaust guys have to make a sharp turn after clearing the torsion bar to get the exhaust away from the transmission, this is why I want this section removable as I need to get the the transmission out without cutting up the exhaust system.

There is room to route the turbo exhaust under the pipe going to the turbo and between the starter and frame, there is no other room down there.

Now if you were to find someone that can cut a hole in the side of the exhaust manifold between  #1 and #2 cylinders, and then weld a flange on it, and then cut the stock exhaust outlet off even with the rest of the exhaust manifold and weld that closed, then you will have lots of room to get the exhaust out thru the stock place/route, but finding someone that can weld cast without it cracking takes talent, I tried getting a Ratsun member on here that welds for a living to do it, but now I am out 4 exhaust manifolds, an intake manifold, and a not so good turbo, he will not answer his phone and none of his friends(members on here) will ask him about it for me, 2 of the exhaust manifolds were not even mine.

You and others were interested in the turbo manifolds like what is on my 521 kingcab but it appears I cannot get it done, so I did it the way I have done it because it is something I can do myself and I wanted to lower the turbo so I could put my stock 720 hood back on the truck, the 1998/99 VW Passat 1.8 liter turbo I am using now appears to be working out, I filled the truck up a couple days ago and I am going to drive it and see what kind of mileage I am getting in the city.

1.8 liter gas turbochargers appear to work good on my 2500cc engines, I suspect a 1600cc turbocharger will work on the 2200cc diesel engines, I believe that was the size of the turbocharger I took off the 720 diesel engine, but that turbocharger was modified and that is why I changed turbochargers, I believe that turbo would be good for drifting or spin out competitions, but it was terrible on the freeway.

Edited January 25, 2019 by wayno

[620slodat]

I know somebody who used to be a welder. I might see his son tomorrow and will see if he knows if his Dad has experience with cast iron. I don't hold up any high hopes because where he worked (probably 15 years) made saw mill equipment, and I'm not aware of any cast iron that is used in making saw mill equipment.

[wayno]

Today I went to the wrecking yard to see if any of the VW Passats had my turbocharger on them as I need an exhaust gasket, no luck on that front, but I did figure out that the 2001/02/03 VW Passats there have the turbocharger that I pulled of the 720 because the former owner modified it, there were 4+ of them in the South Portland yard alone, but last night I also searched VW Passat turbochargers on ebay and they are cheap new, under a $100.00 shipped, I am thinking about getting one and trying it out, it appears to be a smaller turbo(exhaust side) so it will spin up faster than the ones I am using now but it should not move as much air like the modified one I took off which moved too much air.

The turbocharger guy in Scappoose  OR said if I was building up 20psi boost it was too small, now that kind of goes against what most would think, most would believe one needs a larger turbocharger to build up more boost.

 

I believe the trick to welding cast is to completely heat it up real hot, then weld it, then put it in a pre-heated barbecue(charcoal) and let it all cool down slowly, keep in mind there are special welding rods to weld cast also, I would do it myself but I do not see so well when I am welding, I can fix my mistakes on normal steel, but I suspect mistakes welding cast will be way harder to fix.

[Stoffregen Motorsports]

Peening with a hammer while it's hot helps relieve the stress. I wrap with leather blankets and let cool overnight.

 

Another trick I've heard, but never used, is to submerge the piece in kitty litter to let cool overnight.

[620slodat]

21 minutes ago, Stoffregen Motorsports said:

Peening with a hammer while it's hot helps relieve the stress. I wrap with leather blankets and let cool overnight.

 

Another trick I've heard, but never used, is to submerge the piece in kitty litter to let cool overnight.

 

Interesting information!! I don't have any leather blankets here, but I just happen to have an almost full bucket of kitty litter from several years ago, but I don't consider myself to be that good at welding. My medium of "artistic" talent is wood, not metal. Maybe Wyatt will say that his Dad has experience at welding cast iron.