What Are the Weak Points of the 260z (for Endurance Racing)?

[Carl Beck]

Thank-you John, that is very helpful.

Carl B.

[John Coffey]

You could be right, but the suspension was not a random design. Pro Shocks of Lawrenceville, GA specializes in racing suspensions and they did the work. Of course, that doesn't make them perfect... but in late October we ran the quickest lap the car has run since the summer of 04 and finished 1st and 2nd in our events, so they must have done something right. Very slight push in, slightly loose off. Perfectly balanced in the center with good weight transfer and constant, predictable and controllable handling at the limit. I'm all for making it better, but the 19 cars we beat that weekend unanimously agreed that it's not junk.

I didn't say your car or its performance was junk. If your front shocks are Tokico Illuminas (BZ3099 - typical shortened 240Z fronts) then Tokico's engineers and my own personal experience says the rebound valving is gone with springs rates of 350 lb. in. There may be a different Tokico shock in there that have the correct rebound valving for the spring rate. The only two Tokico shock inserts that I'm aware of that can handle those spring rates are the HTS102F and HTS112F.

[sopwith21]

I agree! My only point was that they appear to still be working. And yes, they are BZ3099's. But if the rebound is shot, I should be having rebound problems under acceleration out of a turn. I'm pretty experienced and can't feel any such problem???

[rxsleeper]

Here are some pictures of my brake setup. 2 3" lines to each shroud. Excuse the dryer duct, this was done by the previous owner and has been corrected. FWIW, I run hawk HT-10 brakes in front, and OEM drums in the rear with carbotech shoes. My brakes don't work well until I get several laps on them in a session/race but then work very well, for even the longer races. I do burn out the caliper seals after about 2 races. I check them after every race and rebuild/replace the calipers as needed.

JohnC said it best. The only people that are breaking stubs are usually running a welded diff. I haven't broke one yet but I recently picked up a quaife and I am still looking for a clutch LSD (R-180).

Heat management is the key. Redline in the gearbox and diff. Coolers for engine oil and if legal for your class the diff. I have only had problems with engine cooling when a thermostat failed closed.

Now for the pictures:

A better picture of my current set up

FWIW, this setup was used on my car to win several endurance races on the "left" coast before the car migrated East

Edited January 4, 2011 by rxsleeper

[John Coffey]

I agree! My only point was that they appear to still be working. And yes, they are BZ3099's. But if the rebound is shot, I should be having rebound problems under acceleration out of a turn. I'm pretty experienced and can't feel any such problem???

Rebound issues are generally felt on corner entry and mid-corner. The car turns in well but "falls" over on the outside front shock, doesn't take a set, and then understeers. On corner exit you should see more weight transfer to the rear and understeer.

Your shock may be fine, there are exceptions to every rule, but keep an eye on it. It may not leak any oil and still have problems with the rebound valving. What setting do you run the front shocks at?

[z-spec]

Verry interesting hear technical things about racing Z,s there should be much more written about this .

I run a 4.40 R180 from a Subaru WRX Gr N Rally car , this is a purpose build Plate type LSD diff from Prodrive Subaru STI , we made our own output flanges for the Datsun drive shaft .

I have a 200SX gearbox with a 240Z Bellhouse , fits straith to a L6 engine , with better gearshift and close ratio 2.43-1.81-1.36-1.00-0.82 (Kameari gear kit )

My second option would be a Turbo T5 with a G-Force Close Ratio kit these have more options for 5e gear

For brakes we use the Toyota 4 pot Calipers or the much lighter AP Racing

I do not have expierece with Datsun 240Z in Endurance racing but i have with my 65 Shelby Mustang with Spa 6 Hour and Nurburgring 500 Marathon

We uses yellow Pagid but I prefere Performance Friction , they are easyer to bedding in and frienlyer for the Discs , the rear drums we use Porterfield R4 but the only the racing stuff the other stuff dont last for 6 hours.

Whats actually the minimum weight you can build a Racing Z

[rxsleeper]

Whats actually the minimum weight you can build a Racing Z

Depends on which class/sanctioning body and class you are racing with. In my case, I must weigh not less than 2430 at the end of the race. Last time I rolled over the scales (including my fat butt at 200+ lbs ) I was at 2437 and I had about 2 gallons of fuel left in the cell. I have a friend with a tube frame Z that weighs around 1900 lbs and he still has a lot of steel body panels. He adds ballast to make minimum weight.

Paul

[sopwith21]

Rebound issues are generally felt on corner entry and mid-corner. The car turns in well but "falls" over on the outside front shock, doesn't take a set, and then understeers. On corner exit you should see more weight transfer to the rear and understeer.

We're not getting any of that. The car turns in with slight understeer, then sets and balances in the center quite well, then slowly and predictably transfers weight and slightly oversteers coming off the corner. Everything you would expect with a welded diff. The car does not snap from under to over steer. It's slow and predictable.

Your shock may be fine, there are exceptions to every rule, but keep an eye on it. It may not leak any oil and still have problems with the rebound valving. What setting do you run the front shocks at?

I will, thanks. And now I know what to look for. We set the fronts at 3 and the rears at 2. We've tested them at all settings and this seems to work best on a technical course that averages right at 75 mph.

I suppose we could change the settings to something more extreme, but if you have to go 5 at one end of the car and 1 at the other, to me that's just indicative of another problem somewhere else on the car. I don't think you can over-adjust struts to compensate for another issue... we just need to solve the root problem to begin with and let the struts do their job. So 3 and 2 seem to work okay.

Edited January 4, 2011 by sopwith21

[John Coffey]

Verry interesting hear technical things about racing Z,s there should be much more written about this .

http://www.hybridz.org

[sopwith21]

We're at 2,213 lbs and legal.

[gnosez]

Is your airdam deforming in your avatar picture?? Urethane?

[sopwith21]

Yes, but not due to airflow. When it was originally installed by another owner, it sagged in the center. We tried to bolt it up again after the plastic had developed a memory and it deformed it a bit.