RLY240

no visual deflection.

Hi Justin, sure the wheels may flex but that wont make the calipers deflect compared to the rotors. As discussed before there is no issue on the straight or even while cornering on the street, only when loaded up during cornering on the track and to a lesser extent during a rally. The knock back actually gets worse when the pads wear as there is more travel in the pistons. I resurected this thread recently because TTT now offer a fabricated chromolly stub strut which they wouldn't need to do if the 40 year old standard ones weren't causing some issues.

Stuck a camera under the front guard at Mallala today, video is unfortunately inconclusive. In some corners it looks like the strut-to-wheel gap changes but because the angle changes during steering it makes it very hard to judge. What it does tell me is that as suspected there isn't enough travel in the shocks before the bump stops are reached, I don run long stops but clearly this could use an inch shorter strut. Another project. Roger

Hi Mike, the bearing spacer and piston return springs certainly helped but the effect is still there. I'm going to stick a camera up there for the next meeting and see if I can get some evidence of flex before making the next move. The TTT fabricated struts look very nice but are a bit of a budget breaker at the moment and tapping the pedal is free.....

Tilton twin masters with bias bar and no booster. For sure the effect would be lessened with a larger master on the front but I'd need to spend more time at the gym to be able to press the pedal. There's a couple of things I will try now including removing the spacers and loading the bearings, and sticking a camera under the guard to get a better look, stuff I can try between track days. The pedal at the moment isn't terrible just that it could be and used to be better.

Or that the inherent problem (stub stiffness) is getting worse over time. I'm in the process of rechecking the tolerances to compare to the original work. This really was all triggered this time by the release of the new fabricated TTT struts suggesting the standard ones (with bracing) still had room for improvement.

Yes.

Adding the bearing spacer/stub sleeve is more or less the same thing, the bearing inners are effectively tied together so the only way to put more preload on the bearings would be to irreversibly shorten the spacer or remove it. I'm sure I'll give that a try at some point. Appreciate your feedback.

+1 if the header flange isn't the same thickness as the inlet flange then the bolts don't pull down evenly and leaks are likely.

No brake noise (apart form squeals on some compounds). It's fine after a straight (and on the road) it's only after corner loads. Same for cold or hot. Can drive on the road for kms and not an issue, head out onto the track and a couple of heavy weaves on the out lap is enough to make the pedal drop. Not dangerously low but enough to dent your confidence especially at Mallala which is all brakes. By comparison the long run up Mountain Straight at Bathurst didn't need a tap before a big brake at 180kmh+

Struts are already braced (TTT), stub stiffeners fitted, calliper piston return springs installed, alloy dogbone calliper mounts used. Going to add a camera or tell tale device to actually see what's happening at the next event. Or just put up with the confidence tap.

Struts are free more or less but there's also the costs associated with swapping again (brakes, wheels, dampers, etc) that is a little confronting.

yes.

Not yet but it's on the list. TTT do some custom stuff so you could certainly ask them.

Any difference between the 240 and 260 hub in this department? Looking at them it's hard to imagine and flexing within the hub but Nissan must have changed them for a reason.

I'm dragging up this old thread as the pad knock back has gradually got worse again and although not as bad as before it's still annoying enough to require a confidence tap on the straights before a big brake. The bearing spacers are still in place and don't seem to have lost their tolerance and there are no other changes to the system to explain the faults. Have even used temperature paint on the rotors and f.expensive brake fluid to confirm that it's definitely not an over temp fluid problem. To recap, under racing conditions the brake pedal drops after cornering (not after braking) such than even weaving on the warm up lap is enough to make the pedal drop. I'm now convinced that the issue is in flex or movement of the spindle compared to the strut making the rotor push the pads and pistons back into the calliper. If I'm right then the only recourse is to stop this flex somehow. I've recently noticed that TTT now offer a fully fabricated front strut in CrMo which would presumably be stiffer than the 50 year old cast iron ones. https://technotoytuning.com/nissan/240z/evolved-front-coilover-conversion-datsun-240z-260z-and-280z Anyone got any insight into this issue? Roger

I've also found that swift hammer blows to the body of the upright can help break the bond in the same way you can get a tie rod end out of a steering knuckle. Still needs a press or puller though. Roger

Mine touched 226 last year on the GPS (not this lap).

Ok, my bad.

I'm no expert and I've only seen roughly matched springs. Having a weak and a strong spring of different lengths such as your photo would give a graph that ramped up quickly to a mid point and then take a lot more revs to get up to full advance. To get it right you first need to know what advance graph you want and then choose the right springs to get there (and have a dizzy dyno to measure the result). Or you could do what most of us do and chuck in whatever you have but I think you can still buy the stock springs from Nissan. Roge

The total mechanical advance is set by the weights (they should be stamped with the number) and the springs set the rate at which they advance or where they start advancing in the rev range, soft springs come on earlier. If you replace the springs with something too stiff then the mechanical advance will never kick in. Roger

The distributor shaft isn't one solid piece all the way through it's actually two pieces to allow the mechanical advance to work. It's quite possible that someone has dissasembled it and rotated the top section (part 9 below) 180 degrees on assembly. If this is the case you can either pull it apart and make it right or just move the leads on the cap and pretend it didn't happen, this won't affect the engine at all. Roger

There's nothing stopping you just relocating the leads on the cap 180 degrees.

There is no fuel line reducer on the returning fuel line. ​​This seems odd to me, if there is no restrictor in the return line then the flow will always follow the easiest path back to the tank. The factory fuel rail has a restrictor built in. Roger

Thanks for checking, I'll keep looking!