Datsun Roadster Forum-311s.org

SLOroadster wrote:

gboone wrote:I got my composite springs recently and started the install today. Much less arch than the steel monoleafs and they weigh only 6 pounds each. That negates the weight I added with my new roll bar. Flex Form found an old die for me in one of their drawers, tested it, and it worked well. I may have to add lowering blocks but they'll be pretty thin. We'll see after I install one and sit it on the ground.

I'll bet you have to add some weight to the back end. I'm guessing that I'll end up pulling 20 lbs out of the car, or running a half tank of fuel to get the balance right. It would be nice to loose more, but I don't think its going to happen. With your springs that are half the weight of mine, you will likely have to add more weight than I do to get it balanced right. Time will tell. I'd love to put my car on a set of corner weight scales, I just don't happen to have any.
Will

Will, my battery is mounted the trunk. My car is very neutral balance wise (no oversteer or understeer) and like I said I just added weight with the roll bar over the rear axle. I guess I'll see in a couple of weeks after the SCCA Nat Tour.

Gary, I have a new set of lowering blocks you can have for shipping. I honestly don't remember the height, but I'm thinking they were 1'' or so... if interested I will measure. They however will require that you modify the top metal plate(s) that sandwich the spring as the blocks themselves are longer than the plate and will sit on the plate edges... just grind down the edge so the block sits flat and it should be no problem. They have a locating pin that may also require some minor mod to the mounting plate.
I too am happy with the flexform springs so far. Glad you were able to get this worked out.

I got to get an idea of what the car does now. I found a nice wide radius 15 mph corner and took it in a spirited manor. The back end starts to step out at about 45 mph but then the front end breaks loose and it settles into a gentle drift. Before lowering the back end, the car became a handful at about 25 mph, only the back end was coming around and the front end was staying where it was. Instead of spinning the car now wants to drift in a smooth balanced manor. With real tires on it, I might be onto something. I'll find out at the end of the month (unless I get bored and throw the RA1s back on the car for a little fun...) The attitude of the car feels flatter as well.

Will

I got one of my fiberglass springs installed tonight. I won't need any lowering blocks. They're near perfect for maintaining the height of the rear of the body compared with the Nissan Comp springs.

gboone wrote:I got one of my fiberglass springs installed tonight. I won't need any lowering blocks. They're near perfect for maintaining the height of the rear of the body compared with the Nissan Comp springs.

Cool! Post some pics when you can. My car is 4.5 inches off the ground at the frame in front of the rear wheel as I recall (195/60/14 tires), making it equal to the front comp springs. You said that FF found a different "form" or dye I think... does that mean they made a different spring for you than what I got? If so, that may be the one to go with so that you don't have to use blocks. The ride certainly is a million times better than my old de-arched comp springs, even with the stiffer Gas-adjusts...

Gregs672000 wrote:

gboone wrote:I got one of my fiberglass springs installed tonight. I won't need any lowering blocks. They're near perfect for maintaining the height of the rear of the body compared with the Nissan Comp springs.

Cool! Post some pics when you can. My car is 4.5 inches off the ground at the frame in front of the rear wheel as I recall (195/60/14 tires), making it equal to the front comp springs. You said that FF found a different "form" or dye I think... does that mean they made a different spring for you than what I got? If so, that may be the one to go with so that you don't have to use blocks. The ride certainly is a million times better than my old de-arched comp springs, even with the stiffer Gas-adjusts...

I'll post pics after I get both installed and on the ground. After closer inspection, I think I will install 3/4" thick blocks. But that's a lot better than 2" blocks like I had to use with the steel monoleafs. I pressed Mark at FF for a flatter spring arch and he found this die in a drawer that he hadn't used in years. When I line up the eyes with the Nissan comp springs, the top surface of the FF spring at the axle is 1.125" lower than the comp spring. So there is still some arch but much less older ones. Of course the rear ride height will depend on the spring you specify. That's the beauty of the FF springs.

Got both FF springs installed with 3/4" lowering blocks and the rear sits about 3/4" higher than with the Nissan comp springs but I'm happy with that. My Koni's make the reach. I raced it this weekend in a SCCA Solo 2 National Tour event and got killed. But the springs behaved really well. How is a Datsun roadster supposed to compete with a CSP Miata with 33% more HP and better suspension?
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Gary,

Have been fallowing the post for a while and was wondering on your FF springs if you are using sliders on the rear?

Thank you,

Johnw wrote:Gary,

Have been fallowing the post for a while and was wondering on your FF springs if you are using sliders on the rear?

Thank you,

No sliders. I'm using the factory shackles.

gboone wrote:How is a Datsun roadster supposed to compete with a CSP Miata with 33% more HP and better suspension?

I've thought the same thing, but more on the DP level. I doubt the SEB really cares about a 40 year old car of which only a few turn out, and would be in no hurry to reclassify it. That's why my thoughts turn more to track days than Solo. I can NOT be in a competitive environment "just to have fun." We may as well run in AM as CSP, the odds of being competitive are about the same in either.

Gary, the ride height looks perfect. Interesting that you are still 3/4 inch higher than the comp springs... guess mine where so de-arched that I was seriously low in the rear. I used the "other" FF arched springs, can't remember the weight rating (190-200lb spring as I recall) and needed a 1.5 block I think, with the spring eyes installed reversed for max drop (for those who don't know, the spring eye is bolted and then glued to the fiberglass spring and can be flipped over to provide a lowering effect. The owner can try one way without the glue and then flip it if they want to lower the car a bit, then glue). How many inches are you off the ground at the frame in front of the rear wheel? I think I'm 4.5 off the ground, same in front with comp front springs (with 14 inch wheels, 195/60/14).

Gary,
How is your weight bias, I'm guessing its way far forward. I had 1 CSP miata beat me by just a tick. I also only got 2 runs in before breaking my axel, also I'm on 7 year old RA1s, running in the 2nd run group on a surface that never allows even the softest tires to come up to heat.

I'd think you can run with the CSP Miatas no problem.

Will

I know for a fact you can run with the CSP Miatas,just pay the entry fee and show up.The big question is how can a roadster ever beat a nationally competitve Miata.

Greg, I just took measurements after springs have completely settled. The height from the ground to the centerline of the pin that connects the front of the spring to the frame is 7.00" . That's with my street tires mounted and the measurement from the centerline of the rear axle to the ground is 11.5".

Regarding my Tour event results, I have lots of excuses. My Hoosier A6 tires are almost 2 years old, I got severely dehydrated before the first day to the point where I was blacking out Saturday night. I drank 2 quarts of Gatorade Saturday but that wasn't enough. It was hot as hell on the pavement, like 105 degrees air temp. I'm pretty sure my EFI conversion tune is not optimized even though I had an "expert" dyno tuner did his thing. Compared to my 45mm carbs, I lost 2 HP but the torque comes in earlier and is flatter longer on the rpm scale, compared to the carbs. I'm looking into improving that. My RWHP is only 118 compared to the Aro's Miata's 158 RWHP (they're running variable valve timing too which helps the torque curve). I'm looking at increasing my tires from 225's to 275's but it's impossible to gain 40 HP with a U20 under the rules even if I optimize the EFI tune.

I got corner weights at the Tour event but I think the numbers are reversed front to rear.
But the display said this:
LF 459
LR 579
RF 471
RR 592

Hmmmm 118 sounds a little low,what was the brand of the dyno? Dynojet or?