Tube-frame 1968 Datsun 510 - Slowest moving project ever!

[blueridgespeed]

I don't like cutting upside down, actually I think welding upside down is worse :D

 

Yeah!, well, I've got the spatter-burns in my lap instead of on my neck and shoulders, that's one difference. I know about welding upside down! -that, and there's less of those stray little f*#$@*-ers that tries to jump over the helmet and set your hair on fire! - HA!

[blueridgespeed]

As most folks have figured out, the main hindrance to lowness (other than rear geometry, is clearance for the wheels up into the wheelwells. I'm talking when you're REALLY low here.

 

[blueridgespeed]

 

Well, today I took the 3-inch cutoff wheel, reciprocating saw, and metal snips to the inner fender wells in preparation for the tubs.

 

This will free up over 3 inches of clearance, vertically, above the rear wheels.

 

 

I'll post pics, which should make it more clear, but the fender lip structure and the stamped brace that sits at the 12:00 position above the wheel well will be retained in a way that the new tub will be welded to it. IT'll be very strong, without any "flopping, flapping sheet metal" Many folks might have never seen this brace if they haven't had a car this far apart, but if you pulled off the rear pillar vents and looked down in there, you'd see the braces that tie in the top of the wheelwell housing and then form a support to the outer sheet metal - following the exact shape of the "blood groove" body character line that run horizontally along our 510's

 

 

[blueridgespeed]

Almost done with the other side, and then driveline placement will be ironed out before the inner wheelwells are made. I call these the "outer wheelwells"

 

 

 

[nismopu]

Your car is going to be SO AWESOME!

[Duke]

I don't like cutting upside down, actually I think welding upside down is worse :D

 

 

Jeff, that is why you need a TIG...no problems with welding upside down:cool:

[Icehouse]

Yeah!, well, I've got the spatter-burns in my lap instead of on my neck and shoulders, that's one difference. I know about welding upside down! -that, and there's less of those stray little fuckers that tries to jump over the helmet and set your hair on fire! - HA!

 

 

haha Yeah and then you take a shower and massive hair falls out :D The shirt I'm wearing today is the one I wore when I did my mini tubes, aka full of holes!!

 

The one thing I did different (well I copied Duke :D ) is cut off the step. I can run 7" wide rims with zero offset with little to no camber. Recently Frank picked up the red car which has super rolled fenders, he has 235's on the back!! They took a body hammer and went to town, completely removing the step without cutting any metal!! Everyone has there way :D With your setup you will be able to move the wheel mounting surface inboard so wider wheels won't be as big an issue.

 

Jeff, that is why you need a TIG...no problems with welding upside down:cool:

 

I had a tig, sold it :( I use the one at work all the time tough :D I want to start playing with the pulse width adjustments. I'm thinking of building my own header (got the idea from a really cool dude :D ) I will have to update My 68 thread, actually both of them :D

[blueridgespeed]

I got the other side done and the control arms mounted up to the uprights with new poly bushings.

 

Cutting the wheelwell step like ICEHOUSE did may have been enough, I don't know. Doing the work with a body hammer is a creative idea I hadn't thought of -

 

Anyway, in it's current state, I didn't see any reason not to go for the "max reasonable" clearance (given my preference to retain stock outer sheet metal)

 

Comparing the old housings:

-to the new housings:

Shows the increased clearance.

 

Now on to a "subframe" structure to mount the differential and control arms. The diff COULD come down and out with some fancy manipulation, but we'll probably make it a "top loader" since fabrication of all the sheetmetal above it will allow access from above to be designed in.

[blueridgespeed]

So with your new suspension what is going to be the widest tire you can run?

 

The 15x7's from my 240z bolted right on with the 225/50/15's mounted. No clearance problems at all. I'd say 235's or wider should fit with the correct wheel offset.

 

At this point, the question is HOW much to narrow the rear end. The Watanabes have a slight negative offset and have 195's currently mounted. The half-shafts have been shortened enough to give us some flexibility about how far inward we mount the control arms, and thus the hub faces.

 

Right now we've looked at a lot of options/possible future combinations and we'll probably go 10mm in and run the current wheels with 10mm spacers.

 

Front tire width will probably be the limiting factor (the strut body, of course, presents an inner limit, and offset wheels and/or spacers can't go very far out without flares (especially when the car's low and the top of the front wheel is deep up in the fender. I don't want to deal with rubbing or a reduced turning circle, so I'll probably just run what works on the fronts, and then run a good match on the rears .

[blueridgespeed]

A subframe of DOM tubing with brackets to mount the control arms was fabbed yesterday. We're going to integrate the differential mount on top of this, allowing diff removal/servicing without affecting alignment settings.

 

The diff and control arms ARE independent on a 510, of course, but this is 240z suspension (modified) and the control arm mounts (front) need to be loosened the take the diff out of a z. Most mods to the Z suspension to allow aligment adjustments would also be affected by diff removal. I like the idea of leaving them separate, and independently servicable.

 

Pics to follow soon

[]2eDeYe]

Can't wait :D

[blueridgespeed]

A subframe of DOM tubing with brackets to mount the control arms was fabbed yesterday. We're going to integrate the differential mount on top of this, allowing diff removal/servicing without affecting alignment settings.

 

The diff and control arms ARE independent on a 510, of course, but this is 240z suspension (modified) and the control arm mounts (front) need to be loosened the take the diff out of a z. Most mods to the Z suspension to allow aligment adjustments would also be affected by diff removal. I like the idea of leaving them separate, and independently servicable.

 

Pics to follow soon

 

Edited October 16, 2008 by ]2eDeYe
[IMG]picturelink[/IMG]

[]2eDeYe]

Hawt! :cool:

[Duke]

Very nice, the rear suspension is defineatly one of the weak points of the 510 and I like what your solution has been.

[Icehouse]

OOWWW NICE!!! Is that going to be the hight the center section is going to be welded in at?

[blueridgespeed]

It'll probably end up pretty close to that mocked up height, which is 1/4" up from the current 4" rocker height.

 

Roll center, camber gain, and half-shaft angulation are some of the factors involved in the placement height decision, but the plan is to pretty much mimic close to what's in a s30 Z car. The main difference being that it'll be set up "in it's happy place" ie: no angulated to be at this ride height like a z would be if it were lowered to 4".

[Icehouse]

From what I know about suspension (not that much) Shouldn't the LCA's be at a slight angle down? So when the suspension is compressed in a corner camber is added not taken away? The camera angle doesn't really show 100% the angle of the arms though. It just seems like once the arms have past the horizontal position the suspension no longer adds camber as it's compressed it actually takes it away. With strut suspension anyways. With dual A arms it would be different.

[blueridgespeed]

You are exactly right!. How much of an angle is the question. For, say 3 inches of compression travel, I'd raise the inner LCA pivots (this subframe) up 3 inches to give (negative) camber gain through that range of compression.

 

The problem is, this would give me (negative) camber LOSS on extension, or "droop travel" from the static ride height. No big deal, probably.

 

This susp design gives maximum "length" of the LCA at horizontal, and less as it traces it's arc. Since it's attached to the strut base below the axle centerline and the top of the strut is fixed, any "shortening" gives a loss of (negative) camber.

 

The question is, where do you want that point of maximum (negative) camber to be? Full compression? perhaps. Static ride height? Keeping in mind that anti-roll bars/sway bars can limit roll and thus compression of the "outside cornering wheel" we have that at our disposal as well.

 

Static camber can be set wherever, by altering the strut top mounting point. Then the change from there is what we're talking about. The stock z actually travels through "maximum (negative) camber"(which is when the LCA's are horizontal) after a few inches of compression, and it seems to handle fine. I'm trying to also set this up so when the torque on the half shafts is greatest (likely in the zone from static ride height to full compression) - that the angulation on the half shafts won't be too extreme. If I ever do c/v's they'll have an easy life!

[Icehouse]

Now that is a tough question! Like I've said on project threads before, "The hardest part is planing the car from the beginning, and knowing what the end will hold." Or something to that effect. To know what you want for suspension there has to be a point/goal set for your rig. Something like "I want my 68 to pull 1.1G's in the corners." Okay, Well judging from all the dimes I've had a 300lb coilovers is about as stiff as I would want to go. So if your car is approximately 2100lbs and its close to factory weight distribution (48,52) the rear weight would be about 1k at 1G thats 2k on the out side tire with no sway bar!! Damn I need to dig out some books!! I know there are some equations for this! :D I will get back to you on this :D Maybe they will shed some new light.

[blueridgespeed]

Icehouse, it's eerie how well you understand my project. It's obviously an aptitude of yours - and perhaps some phenomenon of the "brotherhood of the 68 dime"?

 

I don't think I've posted, but in fact I do have 300lb springs selected as my start point. 50:50 is the goal f/r weight distribution, and the VG30ET is definitely heavier than a l20 (by about 150lbs I think) but then again it's going to be WAY back -courtesy of the sectioned cowl and firewall.

 

My goals, unfortunately, are very specific and (with work!) attainable for the things like a. light weight b. servicability c. decent strength/safety but one main handling goal is difficult to quantify - that is...I hate to overuse a phrase...but "fun to drive"

 

I've driven a lot of cars, but honestly my last 510 was the most "fun to drive". So I'm going to try to mimic as many features as I can and hope for the best. More power, less weight, and a stiffer (tube) chassis should put me in the ballpark. Then hopefully the spring options (easy with coilovers) and alignment adjustability (now possible with the new susp setup) will allow me to tune to happiness

 

Thanks for your input. I'm impressed you have any time for this, seeing how you're blazing away on your own project.

[datsunwizard]

Hello, not to step on your very nice build, but this is my similar rear end build, using Miata "A" arms and up rights with STI R-180 rear end. It is a work in process. I can't wait to see how you are going to do the upper frame part of the assembly.

Monte

[]2eDeYe]

I hate to overuse a phrase...but "fun to drive"

.

 

It may be overuse...but that's what it's all about in the end :D

 

 

 

...and I want your shop datsunwizard :)

[blueridgespeed]

Hello, not to step on your very nice build, but this is my similar rear end build, using Miata "A" arms and up rights with STI R-180 rear end. It is a work in process. I can't wait to see how you are going to do the upper frame part of the assembly.

Monte

 

Datsunwizard/Monte - you didn't just step on my build, you snatched it up, hurtled it from my shop down the river to the crusher, and had it hydraulically compressed into a twisted cube of steel unworthy of even being MELTED DOWN to be used for one of your projects! Ha!

 

Seriously, though, what you've done there is amazing. You're in another league, but in my own defense, I've got to learn somehow! I'm doing the best I can with what I've got, man!

 

Sheesh, that green Decker unit in one of those pics probably cost about 3 times my whole shop AND my project cars. Please tell me you don't own that.

 

Seriously nice work, though. The eccentric adjusters are a nice touch, and I like the "monocoque-ness" of it - I can make that be a word, right?

 

No doubt that kicks my arse SOUNDLY, but then again, the old BRE cars were running L16 and L18's, and (modified) stock rear semi-trailing arms, and THEY did pretty good. Good enough to be fun for me! I'm not saying that modern isn't much better (heck, I'd have done superlight unequal length A-arms if I had the gumption) but I decided to work with what I had, and the best-looking stuff I had was some 240z stuff. So here I am.

 

(Ok, I'm going to go cry a little bit now)

[datsunwizard]

Datsunwizard/Monte - you didn't just step on my build, you snatched it up, hurtled it from my shop down the river to the crusher, and had it hydraulically compressed into a twisted cube of steel unworthy of even being MELTED DOWN to be used for one of your projects! Ha!

 

 

Thanks for the compliment.

 

 

Seriously, though, what you've done there is amazing. You're in another league, but in my own defense, I've got to learn somehow! I'm doing the best I can with what I've got, man!

 

 

I think that you are doing a fantastic job!

 

 

Sheesh, that green Decker unit in one of those pics probably cost about 3 times my whole shop AND my project cars. Please tell me you don't own that.

 

 

Don't hurt me but, I own two of the Deckel's, a manual mill and a CNC mill.

 

 

Seriously nice work, though. The eccentric adjusters are a nice touch, and I like the "monocoque-ness" of it - I can make that be a word, right?

 

 

I am still aren't done with the lower sub frame yet, it is just tacked together and i am going to put some large holes in the bottom for lightning and for diff draining. My next part of the project is to start working on the upper frame assy, which will mount the top of the diff. to the car and for mounting the coilcovers and the upper "A" arms. If you want to check out my build go to http://the510realm.com/phpBB3/viewtopic.php?f=3&t=8375 for more pics and why I have done certain things.

 

No doubt that kicks my arse SOUNDLY, but then again, the old BRE cars were running L16 and L18's, and (modified) stock rear semi-trailing arms, and THEY did pretty good. Good enough to be fun for me! I'm not saying that modern isn't much better (heck, I'd have done superlight unequal length A-arms if I had the gumption) but I decided to work with what I had, and the best-looking stuff I had was some 240z stuff. So here I am.

 

(Ok, I'm going to go cry a little bit now)

 

 

 

If you want some help in brain storming and sharing ideas do not hesitate to contact me. I will be watching your project very closely. Wishing you the best!!!

Monte

[blueridgespeed]

The rear suspension planning needs to integrate into the frame of the car as smoothly as possible, so many factors needed to be sorted out before proceeding with the subframe.

 

The LCA mount point was selected (2" above horizontal at ride height - so maximum (negative) camber at 2 inches of compresssion)

 

Then mockup was done inside the shell, and then the shell was lifted off

 

Then the diff placement was settled on, and bracketry fabrication began for that...

 

My camera battery quit, so I'll post a pic or two later that gives better perspective...