Well this is my second try... My first post got deleted, the sight timed out. How frustrating! Lets see if I can remember everything I was trying to ask....


I actually don't own an FD, a friend had one. I was very impressed at how well it handle with aftermarket springs and dampeners. After some google searches I had to have it! The suspension part anyways. Being into old Datsun's I've wanted to graft the complete front and rear suspension into my car for at least 3 years. Being such a big project I've avoided it at all costs. It seems no matter how hard I try I just can't get the pogo stick suspension where I want it. 510's come stock with a steering box (ickk!!) So I've done a few rack and pinion conversions. The difference is amazing, but with power increases the car needs better suspension. Since it's not a 100% track car I have to deal with crappy roads. When I switched from my ES100 summer tires to some auto-xing tread wear 50, 235 45 13's it got very unstable on bad roads. I've tried adjusting toe, camber, caster. I've come to the conclusion it would be better to just start with some real suspension. To make sure it's exactly what I want I figured I would ask the guys who deal with it on a day to day biasses. So here they are..

1. When running DOT approved race tires does it affect how stable your car is at high speeds on rutted or grooved roads? (especially you non power steering guys)

2. Will 15" wheels fit over the stock brakes?

3. How low can an FD be lowered before suspension angles cause real problems? (just in case I can't raise it enough in my car)

4. Any advice would help. (Yes it would be cool to own an FD but I don't see it in my future )


Here are some pics of cars me and my buddy built. I know on the datto forums it's hard to put effort into a post when you feel the person will never actually do what they say they are going to do. With that said I could post updates here if you want.


My SR car, soon to get FD suspension




We build this one for my buddies son.




Saved this one, PO pulled everything off the front end to "do a motor swap" after 2 years of being stripped down he put it on CL and we picked it up and put it back together.







Installed the non turbo SR in this one.







A buddy wrecked his car so we fixed this one. I hate drilling spot welds!




After paint. (for some reason my cell phone made the paint look orange)





Pulled this one out of someone's back yard. No drive train and the suspension was put together SO BAD!! That was a lot of work.



dual cam KA in that one




That's just a bit of what we do. The list goes on. Hopefully you guys take my questions seriously.

Basically I'm sick of engine swaps. Besides that it's all about the corners!!

This should most likely be at the top but I did a bunch of searches. I did find the exact answers I was looking for.


Thanks in advance

 

No. But the heatcycling from driving them on the street will kill them quickly.

Yes, if you have the proper backspacing.

 

You have to admit they are damn fun while they last. It's like race gas on a boosted engine... MMMHHH putting the timing back

Awesome!!!

 

Like majik said, no, but its possible they could tramline worse due to their super stiff sidewalls. If you "need" r comps on the street you should have your license revoked. You have to being driving super hard to even begin to push an auto-x tire and that sort of **** has no business on any street.

Your toe and caster have the biggest effect on straight line stability. More toe in + more caster = more stable.

You can lower any double wishbone car til the lower arm is just under parallel to the road. Any more causes geometry issues like whoa.

Nice cars, always had a soft spot for 510s. Please keep your aggressive driving on the track and don't crash a nice car doing something dumb.

 

Dude! Where're you at in WA? ha ha ha, j/k. I moved from WA already.

Anyway, good luck on setting up your cars.

 

2 no's, that's good to hear.


Everyone is entitled to an opinion.


Why are the DOT approved then?



I've noticed that in my pogo stick research. I'm more curious how stock FD suspension does with no mods though. Kind of a base line.





Thats kinda what I figured. Similar the strut suspension.



I really don't drive that fast, I just don't like slowing down for corners. Basically I just want to be able to run some good tires at freeway speeds (70-80 in Seattle) on the way to events if they are close. Its not fun to be scared driving in the slow lane if the ruts are big.





I live near the space needle. So you know the roads I'm talking about

 

I've driven a entire summer on ra-1's(5-6k miles) and a few track days mixed in without any problems. They seem to be one of the few r-comps that are not affected by numerous heat cycles.

 

low offset wheels can also cause tracking. are the R-comps on a different wheel than you ran before? if they stick out more, they can get twitchy over uneven surfaces.

 

I'm glad to hear you had good luck. I'm excited to get cutting and get this project under way!



Yeah the wheels were 0 offset, that's what I think the problem is to, but the only way to get tires that wide (235's) to fit a dime is with 0's. The tires comes within a 1/8" or so of the coilover on the strut. The only real way I could see fixing the problem is to run struts off an even newer car that has more spindle angle then run a wheel with more a positive offset. Which is fixable and not to far out of reach. Instead of spending months fixing pogo stick suspension I'm ready for something bigger and better.




So from what I gather FD suspension with wide sticky tires does fine at high speeds and rough roads?

 

generally speaking, every car will get worse as the tires get wider, because the offset required to fit those tires is lower than stock.
just something you gotta accept and deal with, or run a lot of toe in..

 

So you've never ran racing tires on stock wheels on the street.

 

love the 510s. i raced against them in B/S for 10 years and w the factory racing program they were tough customers. and thanks for saving them.

you PM'd me re how the FD suspension is w R DOT tires on rough roads.

the FD suspension is pure racecar. it is excellent anywhere if it is properly set up. period.

as to adapting it to the 510.

once you strip a car down to it's bare bones it becomes apparent how flexible the chassis is.

once you put stiffer springs larger stickier tires, bars on the chassis it is essential to stiffen all the chassis load points w a roll cage or you end up just flexing the chassis and not achieving cornering force. especially the 510 which is a simple box.

so job one is to re-inforce the chassis. that would need to be done after the fd suspension is mounted of course.

as to ride height... the upper A arm of the FD suspension needs to be adjustable as to length if you lower the chassis more than a couple of inches as it goes negative w bump and it gets to a point that it can't be adjusted out.

hc

 

Do you have any old pics perhaps with your car next to a 510?




The exact reason I want it in my car.




I plan on doing some chassis stiffening, I'm not sure about a full cage but I would like a nice weld in roll bar (more than 4 point) I just don't want to many bars but who knows at this point. I do have 2 510's maybe I should install a full cage in this one.


What is the fix? Shimming the tie rods down to get rid of bump steer?


So getting the suspension at my desired ride hight is critical... That's kinda what I figured.


I'm all for fully adjustable suspension but I don't like seeing custom suspension will millions of extra "just in case" holes. I would like to plan my project a little more than that


Lastly do you have any pics of what is commonly done with FD suspension. I've read about replacing some rear bushings, that's about it besides coilovers and swaybars.

I found a few pics doing a google search, not many though....


Thanks!!!

 

Just FYI - there are various cars out there with dual A-arms up front. The miata also has the same suspension design. I think some of the earlier Civics also had dual A-arm suspension up front.

I say that b/c you don't specifically need to use FD parts to accomplish your goals. In fact you might be better off use parts from another car with dimensions (particularly width) closer to the 510. The FD is a fair amount wider than the 510. Getting the arms to fit might not be worth it or even doable. It is probably cheaper to use donor parts from those cars or even aftermarket parts for those cars that can be modified for use in your car.

You don't need the FD's rear suspension subframe either. You'll probably run into the same problem in the rear b/c the FD is longer and wider than the 510. Its a pretty standard multi link design. There are lots of cars out there these days that have a similar design.

I read an article a while back in Grassroots Motorsports where they used a bunch of Miata components on the 510 chassis. I don't remember if it was solely drivetrain or if they did suspension changes as well.

Good luck on your project and keep doing your research.

 

Yeah the Miata is the only other car I can think of with small dual A arm setup. Honda has IMO Gay front suspension, to me it's similar to z32 suspension. I'm not really a fan, yes it's designed to fit into a tight area but other than that it's kinda cheesy. I like how straight forward the FD setup is, a standard dual A arm setup with big brakes and aluminum arms. yeah A arms are only 50% unsprung weight but it's still cool that they went to such great lengths.


From looking at pictures not actually measuring the FD A arms look shorter than the Miata ones. The price also won't be bad since importing front clips is so popular.


I just want the sub frames so I can get all the pivot points, then build my own custom one a bit narrower. A friend of mine installed z32 rear suspension in his 510, he needed something to handle the RB26DETT he installed though


See if you could find out what issue I would like to read the article.



When I get started I will post up progress

 

Click to view full size!

Q: Do DOT racing tires affect handling on rough roads?
A: They sure make the ride worse!

I wouldn't ever go fast on bad roads for it to matter.

 

That's not really and answer, it's more of a "by the way" kinda deal.


It's funny you say that, my girlfriend says most roads aren't bad my car is just to low She drives a Mercedes though..... Basically a couch on wheels.

 

All performance tires get less comfortable on bad roads. Tires are a very important part of the total spring stiffness of the suspension. The stiffer sidewalls of racing tires and high performance summer tires will ride noticeably rougher than a regular all-season tire.

Very grippy tires will also dart around more on the road, and on bumpy roads it can feel very unstable.

Of course, lowering means you need stiffer springs to keep it from bottoming out. On the FD, about a 1.25" drop is perfect before suspension angles lose their excellence. Stiffer springs also affect ride quality. So keep that in mind.

If you're interested in an FD read the 3rd Gen FAQ and all the stuff listed under "Buyers Guides".

 

Yeah I've noticed all of that, I was more or less just wondering how the FD compares to lets say, a first gen RX7 or any pogo stick car for that matter.




1.25" Good to know, thanks!

Do you have a link?

 

Depends, exactly what kind of tires you're talking about. When running autox special race tires, pressure play an important role. With more pressure, stiffness increases and wont absorb as much shock, transferring through the suspension, to your body.

In terms of rutted or grooved roads, this usually depends more on tire width. If it's wider, it will tend to track in ruts and grooves more.

Now as for high speeds, and high speeds on rutted or grooved roads, they have been fine. The Toyo RA-1s (and other DOT-R tires i'm sure) provide excellent grip and very positive, confident feel. They track quite straight, even with 305 width tires, and feel supremely confident all the way up through 190mph. There is absolutely nothing scary at all about going 160 on these tires every day. They will take it. However, high speed stability is also largely based on chassis, which might have accounted for how stable my experience was.

 

I don't mind a rough ride. I've learned over the years that's why they invented nice seats



Exactly why I was wondering how the FD performed before I get carried away with the Sawlzaw.




Finally, the guy I've been wanting to talk to! So let me get this straight you have 305's in the front of you FD? What chassis mods have you done? Details!!

 

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/faq-3rd-gen-other-useful-links-68640/

Suspension:
https://www.rx7club.com/suspension-wheels-tires-brakes-20/howard-colemans-fd-chassis-setup-723617/

 

Thanks Dgeesaman!!!! I really like Howard's suspension setup thread. I like how technical it was.


This is a great sight for technical info, I read it every night. The biggest problem I have now is I kinda want an FD haha Hopefully the suspension will be enough