620dude Posted June 16, 2016 Report Share Posted June 16, 2016 So, I should start by saying that I bought this truck off a guy who was on his was to turning a 1975 datsun PL620 into a rat rod.. Things he modified were: Nissan Silvia Engine: SR20 non turbo direct Brembo Disc brakes and 5 speed transmission he also took out the torsion bars and replaced it with double adjustable coil over shocks. Here's where I need help. He cut the springs on the shocks (why? I don't know, cause these shocks should be adjustable to get whatever ride height you want!) they were nearly ruined when I got the truck. I replaced the front tires and afterwards realized that the passenger side shock snapped at the base where it bolts in. NOW I AM IN NEED OF NEW SHOCKS AND AM THINKING I SHOULD STICK WITH THE DOUBLE ADJUSTABLE COIL OVERS, UNLESS THERE IS ANOTHER AND MORE AFFORDABLE OPTION. WHICH BRINGS ME HERE. DOES ANYONE HAVE ANY TIPS? OR HAS ANYONE CONVERTED THEIR DATSUN TO SHOCKS AND HOW WAS THE BEST WAY TO GET A RIDE HEIGHT THAT MATCHES THE ORIGINAL RIDE HEIGHT OF THE 620? any help appreciated!! thanks!! 1 Quote Link to comment
datzenmike Posted June 16, 2016 Report Share Posted June 16, 2016 Cutting a coil; spring increases the stiffness or spring rate. If the spring was too weak for the weight of the truck front end, cutting them could be one way to go. Cutting should never be done to adjust the ride height. The chances of getting the ride height AND the stiffness right where you like it is very remote. Type 620 coil spring into the search engine top right of every page and start your research. 2 Quote Link to comment
Lockleaf Posted June 17, 2016 Report Share Posted June 17, 2016 Pics are going to help your cause a great deal. Let people see exactly what you want to replace and you will get more accurate help. 2 Quote Link to comment
5t341tH Posted June 18, 2016 Report Share Posted June 18, 2016 He's done a great job on the car. Let's see pictures of the setup. Quote Link to comment
distributorguy Posted June 19, 2016 Report Share Posted June 19, 2016 You may want to get in touch with QA1 in Lakeville, MN about shocks. They may be helpful in figuring out what will ride best. High quality affordable stuff. Quote Link to comment
DanielC Posted June 19, 2016 Report Share Posted June 19, 2016 "TO GET A RIDE HEIGHT THAT MATCHES THE ORIGINAL RIDE HEIGHT OF THE 620?" Make it original again. Very few people and I do mean a smaller than you think are as smart as the Nissan engineers who designed the truck in the first place. A stock Datsun is a reliable and safe Datsun. 2 Quote Link to comment
]2eDeYe Posted June 20, 2016 Report Share Posted June 20, 2016 If the coil over has snapped chances are it is not mounted correctly and is in a binding state. Just replacing it may not address the root issue. Pics would help a lot with troubleshooting your setup. 1 Quote Link to comment
620dude Posted June 21, 2016 Author Report Share Posted June 21, 2016 ok I'm looking at the QA1 coilovers...pretty sure they will work. does anyone know what the front end weight of the truck is? I know the whole thing weighs about 2300 but I'm trying to decide a good spring rate... 400-450 sounds about right but I'm not sure Quote Link to comment
2wheel-lee Posted June 21, 2016 Report Share Posted June 21, 2016 Spring rate required is also determined on leverage ratio. In other words, where the lower mount is attached to the lower control arm makes a difference to the leverage ratio. 1 Quote Link to comment
]2eDeYe Posted June 21, 2016 Report Share Posted June 21, 2016 Also sprung weight vs unsprung weight should be taken into account. A 620 Kingcab weighs about 2650lbs, about 60% of which is over the front end. Of course part of that is the tires and control arms (unsprung weight) Quote Link to comment
2wheel-lee Posted June 21, 2016 Report Share Posted June 21, 2016 My earlier reply was incomplete, and really, you're not going to get all the information you need here, especially if you're not familiar with suspension setup. Springs are measured in the amount of force required to compress it 1 inch. Other than leverage ratio I mentioned above, you also need to take shock stroke length into consideration. For example, if you're running a 3" stroke shock, you may want the static ride height to have 30% sag - or 1". However, if you're running a longer stroke shock, you might want more than 1" of sag. In short, without having the slightest bit of information on the suspension on your truck, there's no point in even guessing what spring you need. 2 Quote Link to comment
datzenmike Posted June 21, 2016 Report Share Posted June 21, 2016 See post number 2. Contact someone who has done this (or it may be in the text) for a spring rate to start with. Quote Link to comment
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