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

[gnosez]

Well first I suggest you spend the next week or two researching Zs and all related racing info. If you don't know what a "b" tranny is then you need to do some catching up.

So here's a freebie - there are a number of 5-spds but for most people they break down into a few simple types;

1) 77-79 "a"

2) 80-83 "b" - for me there is a subset for the '80 tranny which I prefer

3) turbo BW

4) Z32 w/adapter plate

5) truck, SX and others

All this info and more is out there. Spend some quality time getting up to speed (no pun intended) and then ask more detailed questions. Most of the things you want can be found a click or two away.

[gnosez]

Triple SUs? Okay. What fuel pressure? Is 230 the coolant temp? If yes you have issues.

We have run for nearly 6 hrs with only refueling stops and not overheated our 240.

[sopwith21]

Well first I suggest you spend the next week or two researching Zs and all related racing info. If you don't know what a "b" tranny is then you need to do some catching up.

I misread your post... thought you typed "lb."

I didn't put the tranny in but can find out if it's an early or late edition. I'm sure it's not a Borg Warner.

Either way, the question still remains. I would think that the 4-speed would be preferable to an early 5-speed, but the B 5-speed would be preferable over the 4-speed.

[sopwith21]

Triple SUs?

Yes.

What fuel pressure?

Dunno yet.

Is 230 the coolant temp?

Yes. Temps were awful until we dumped a lot more fuel into it. Now it peaks at 230, rides around 220-225. Would sure like to drop 20 degrees or so.

[preith]

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.

Speaking from experience, a Quaife WITHOUT a cooler will lead to trouble. My R200 without one was hitting 300 degrees at the end of a 1/2 hour session.

No experience with a welded, but I'd venture to guess it would operate a bit cooler. The flip side is it does put additional strain on the halfshafts - the only time I'd hear about guys breaking them was with a welded diff.

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

2nd on the ATF/swepco, my synchros were getting a bit tired, this cleared up the grinding immediately, and the shifts were quicker too.

So here's a freebie - there are a number of 5-spds but for most people they break down into a few simple types;

1) 77-79 "a"

2) 80-83 "b" - for me there is a subset for the '80 tranny which I prefer

Technically both the 77-79 and 80-83 5spds are "b" transmissions, all fs5w71b's. I ranted about this on the transmission/diff setup thread. While yes, 2-3 is a bit closer on the 80-83, for all practical purposes 1-4 on both the 4sp and 5sp (77-83) are the same. You're not going to see any big difference until you go with something like an option 2 comp box or ratios similar to that. The only time I'm going slow enough to use 2nd is at race starts or with lapped traffic.

[preith]

I've been told that the trans should be double roll pinned, but we haven't had a problem with our stock trans(s).

This has been discussed at length on other threads. IMO it's really for the most ham-fisted drivers. Many speculate the actual problem is the pins "walk" out of the forks and some guys actually safety wire them in place.

[cygnusx1]

As for cooling, you may want to take a look at the aerodynamics section at hybridz as well. There are basic aero tricks that a racing S30 should have. Some of which relate to cooling.

[gnosez]

Most of the aero tips can't be used in SCCA or vintage racing sad to say. We just removed the MSA Type II airdam, the blocked off grill areas, the radiator shroud, etc. to make our 240 fit VRG and SVRA rules.

[John Coffey]

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.

OK... you don't have a live axle, you have a welded diff. Live Axle is what's under 1970s Chevy pickup trucks. You front Tokico shocks (unless they are HTS shocks) are junk by now with those spring rates.

Shoot for a constant 200 degree coolant temp on the track. Oil temps should be around 230 to 250 with synthetics. If you don't already have an oil cooler, put one on immediately. Stick with the R180 diff and run a real limited slip unit. Add a diff cooler if you're running sessions over 1/2 hour. For anything over an hour you'll probably need a trans cooler - depending on how hot it gets where you race. Redline MT90 in the trans and 80W/140 in the diff.

Get rid of the Porterfield brake pads and move up to at least Hawk Blues. Get as much air to the front rotors as possible (two 3" ducts are best, one to the caliper and one to the rotor).

Keeping a car alive in an endurance racing is mostly about heat management (coolant, engine oil, trans and diff oil, brakes, driver comfort, and tires.)

For spares you should bring one of everything and, if possible, four completely assembled suspension corners. You'll need the equipment to do complete oil and fluid changes, brake bleeding, caliper and rotor swaps, and draining the fuel cell without spilling a drop.

[Carl Beck]

Replace 1/2 shafts w/ZXT CVs and 280 stub axles.

I have a couple questions about swapping stub axles.

1. The OP said he has a 260Z - looking at the parts catalogs - it seems that the 260Z and 280Z got the same stub axles to begin with - after 08/73 {yes/no??}

2. The original 240Z stub axles - mounted in the strut housing - with a spacer {size A, B, C} and washers at each end of the spacer - between the inner and outer bearings. It seems that the 260Z and 280Z stub axles still use the spacer {A, B, C} but without the washers on each end.

So the question is - if you swap to the 280Z stub axles into the strut housings machined for the 240Z set up - do you have to use the washers or not?? Put another way - is there a difference in the machining or build of the strut housing - where the stub axles mount - between the 240Z and 280Z struts? {not talking about strut tube thickness}.

I'm trying to rebuild a set of 73 rear struts - the previous shop took the stub axles out - and it seems they lost the washers that go on each side of the spacer. Looks like I could just get a set of 280Z stub axles and use them without the washers. {the washers are NLA}.

FWIW,

Carl B.

[John Coffey]

The point of the distance piece (spacer) and washers are to end up with end play and rotational torque with the specs listed in the FSM. Generally the spacer goes with the hub so in the 280Z, MM stub axles installs I've done in 240Z hubs, I assemble with the 240Z spacer and no washers and then torque to 175 ft. lbs. I then measure end play and turning torque. If they are within spec then I'm done.

If the end play is out of spec, I increase torque in 10 lb. increments until the end play is within spec or I reach the max torque number listed in the FSM. If I reach the max torque spec I go with the next shorter distance piece and try again. I've had to do this only once in the last 8 years

If the turning torque is too high I disassemble and add one new copper washer between the inner bearing and the spacer. Then re-torque to 175 ft. lbs. and check again. I've never had to add more then one washer and that is only needed in about 20% of the assemblies I've done.

[sopwith21]

You front Tokico shocks (unless they are HTS shocks) are junk by now with those spring rates.

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.

Shoot for a constant 200 degree coolant temp on the track. Oil temps should be around 230 to 250 with synthetics. If you don't already have an oil cooler, put one on immediately. Stick with the R180 diff and run a real limited slip unit. Add a diff cooler if you're running sessions over 1/2 hour. For anything over an hour you'll probably need a trans cooler - depending on how hot it gets where you race. Redline MT90 in the trans and 80W/140 in the diff.

Good thought on the diff cooler. Oil cooler is already in the plan. And thanks for the temperature levels and fluid recommendations - we'll use them.

Get rid of the Porterfield brake pads and move up to at least Hawk Blues. Get as much air to the front rotors as possible (two 3" ducts are best, one to the caliper and one to the rotor).

Already ducting 4 inches through both headlight holes to no avail. We'll look at the Hawk Blues upgrade, but I don't think anything short of a serious system upgrade is going to do the trick.

Granted, we were running a very tight track that's murder on brakes, but we were boiling fluid within 20 miles of racing. And it's not the driver. I think I'm going to follow your advice on the pads and the previous advice on new rotors/calipers as well. It's a total system upgrade, I'm afraid.

Keeping a car alive in an endurance racing is mostly about heat management (coolant, engine oil, trans and diff oil, brakes, driver comfort, and tires.)

Excellent way to put it. Good thoughts. Thanks!