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

[sopwith21]

Here's what we have:

• 1974 260z early production
  
• 1983 L28, N42 head
  
• Not sure if we have an R200 or 180, but it's a live axle (welded diff)
  
• Coilovers
  
• Crummy stock brakes soon to be replaced
  
• Close ratio 5-speed
  

Hi guys;

For some years we've raced our 260z on off weekends at local and regional club events with some success, winning 21% of our events. But now we want to take the same car endurance racing in long distance events and that's a whole new ball game. So the million dollar question is...

What weaknesses does this car have that should be addressed prior to an endurance race?

These are the problem areas we've had with this car so far:

1. Occasional broken half shaft
   
2. Dead ignition module every few races
   
3. Weak 5th gear that we're afraid to actually use in a race
   

If I pick up one extra half shaft, will the same one work for either side?

Is there anything we can do to permanently fix the recurring ignition module failures?

What else fails on these cars, and how should we prepare for it?

Many thanks for all your thoughts!

[5150 will]

I'm not personally aware of endurance issues, but there are some guys that run a Z out of the Northwest (Washington or Oregon I believe). They have run all of the 25 hours of Thunderhill races and they have over 10k race miles on their car. The thing is typically like the energizer bunny so they know whats what with the endurance end of the Z. I believe they go by "C note racing" in the IRDC and NASA. They would definitely be the people to contact.

Edited January 1, 2011 by 5150 will
add on info

[ajmcforester]

Design wise not a whole lot. I know that some people in the 70's ran a front bearing oiler system, that was very rare.

My biggest concern would be age with metal fatigue. 35+ year metal that has bent and flexed and vibrated, then put it under 20-24 hours of hell sounds like a potential for failure. So I'd check the metal.

The car isn't as convertible for racing as some newer car so anything that can be done to reduce driver fatigue would be smart.

[cygnusx1]

Stub axles, I would venture to guess. Maybe get a set of billet ones from MMS. Do the rules allow you to modify or upgrade the ignition system in any way? If so there are dozens of systems that can be more reliable. Get rid of the welded diff and get a good LSD unit in the car. The welded unit could be helping to tear up axles. Quaiffe comes to mind. A locked diff might make it push on corner entry as well.

Edited January 1, 2011 by cygnusx1

[sopwith21]

We've never opened the rear end of this car, so give me some basics... do we want the 180 or 200? Do all 200's come as LSD's?

[Zealous]

Will is correct C Note Racing is their name and they run a lot, if you can contact them the guy who owns the car is Manfred. Sorry I don't have his contact details. I helped them with the 25 Hours of Thunderhill this year. Problems they had this year included alternator failures, chewing through alternator belts and a Broken Rear Diff Mount. Their alternator was a high output one, especially for when running the lights at night.

You could also call Les at Classic Datsun he deals with a lot of Datsun vintage racing customers and probably knows the weak points better than anyone.

I would say from what I have seen:

• Half shafts
  
• Stub axles
  
• Diff mount
  
• Extra alternators
  

I also believe there was a post on here or hybridz about spares needed for 240Z most is probably valid for a 260Z.

You probably have done it already but I would try to track down what is causing the ignition module failures, maybe changing the mounting location or grounding is causing the problem? I have no experience with those problems.

[cygnusx1]

Get yourself an R200 if you don't already have one. I am not sure if the 260's are setup with the 180 or the 200. My 260 specific knowledge is weak. If it's a 180, you need to get appropriate axles and stub shafts to switch to the 200. All Datsun R200's are open diffs with much stronger spider gears than found in the R180. There are internals you can swap to make the R200 into an LSD. Search OBX, Quaiffe, or you can track down a Nissan R200 LSD which came in one very specific model year turbo 300ZX (1986?), white in color. You can also convert to an Infinity Q45 LSD rear end with more custom work. A must, as mentioned above, is to replace the front diff mount with an engineered RT style mount, or a solid mount.

Oh, and one more thing, left and right axles are not interchangeable, as far as I know, due to lengths.

Search over at HybridZ.org for all the terms and acronyms I mentioned here.

[Jeff G 78]

Yes, all 260 (coupe's) came stock with R180 diffs and yes, we did break ours in LeMons endurance racing. You will also need a R200 mustache bar to make the swap.

You can use the short side half shaft on either side if needed, but it's best to have both and mark them. There isn't much length difference.

Which distributor do you have? We have had stock ignition modules fail. We borrowed Geezer's ZX dizzy and module and we plan to swap once I buy one. Those too are know to fail often, so I'm not sure what the best long-term solution is.

I've been told that the trans should be double roll pinned, but we haven't had a problem with our stock trans(s). We did break a trans housing when the R180 diff broke. The vibration and shock cracked the housing that holds the rear seal.

Edited January 2, 2011 by Jeff G 78
Added info

[jmark]

Gira races an ITS 240Z in the SCCA endurance races. He can advise you.

[gnosez]

Pertonix and an MSD box will fix that dizzy issue for good. Then megasquirt if you plan on EFI.

Where are you driving that you need 5th gear??? In the past 7 yrs I have had our 240 in 5th maybe a dozen times at best. With the current engine (185hp@rwhs) we topped out at 135mph. The new engine will add another 50 rwhp so maybe we'll get into 5th more often.

By close ratio do you mean a 280b tranny? If yes, then fill w/ half Swepco and and ATF.

Remove welded diff, get LSD or Quaife (3:90 gears for all around track use). Install RT mount. Replace 1/2 shafts w/ZXT CVs and 280 stub axles.

Z31 calipers and Porterfield pads in front, Porterfield shoes in the rear.

Engine cooling and oil pressure are your best friend. Plan accordingly.

Please provide more info on your car's specs.

[sopwith21]

Very helpful, guys. Keeping notes on everything. Keep it going. Tx!

Pertonix and an MSD box will fix that dizzy issue for good.

Already have the MSD box linked to standard ignition. Of course, that may be the electronic equivalent of pushing a bowling ball through a straw, but we're halfway there.

Where are you driving that you need 5th gear???

We're not. The question is whether to use the close ratio 5-speed and risk a missed shift and blowing the tranny, or use the 4-speed with the wider ratio and eliminate the concern over missed shifts.

By close ratio do you mean a 280b tranny? If yes, then fill w/ half Swepco and and ATF.

Never heard of a "280 lb" tranny. I'm talking about the close ratio 5-speed that had a smaller gap between 2nd and 3rd. Used on ZX's from - I think - 75 onward.

Z31 calipers and Porterfield pads in front, Porterfield shoes in the rear.

Already using Porterfields. The caliper change must be the key.

Please provide more info on your car's specs.

Next post. Tx again.

[sopwith21]

Additional notes:

Triple SU carbs. Was cutting out in left hand corners at the last race. Hmm. Holley Blue fuel pump. Will send carbs in for service, including bigger jets, and replace all rubber fuel lines.

New engine. Two races on it. L28 with N42 head, +.030, 11.9:1. Ran hot until we poured tons of fuel into it. Now it peaks around 230 degrees in a 30 minute event in 65-degree weather. I'm still worried about long distance races.

15x9 wheels with Hoosier DOT's. Good combo so far.

Stock brakes. Porterfield pads. Upgrade already planned.

Suspension is good. Coilovers and Tokicos. 350 lbs in front, 250 lbs in rear. Handles very nicely. Slight push in, loose off, due to live axle.