260DET

The topic question was prompted by an experience with the original solid front rotors. Fitted Toyota 4 spots and went out to the track. They worked quite well but got a bit hot, actually they turned blue in colour. Driving home there was a bit of shudder through the steering wheel when braking. Checked the rotors with a dial gauge when I got home and found they were warped, not badly but over max specified runout. Obviously the 4 spots were too effective

Problem is I have to have a mechanical handbrake to be street legal. The PBR combination type caliper will have to do, not pretty but they are light.

Yes, USE RELAYS I used a fused relay and therefore was able to take power for the lights directly from the starter motor terminal, using a very heavy cable, about 30 amp wire? Now, the headlights are like brilliant. Don't know what bulbs are in it but they certainly work. On the dash lights, you can get slightly more powerful bulbs than stock but don't get the big glass ones. Clean the green bulb shrouds thoroughly, or remove them completely. I would guess that white faced gauges would improve the situation as well.

Thanks for the tips, the car is used occasionally for supersprints which involve timed laps of a racing circuit, not wheel to wheel racing. As I see it, the 300zx solid rotors are larger in diameter than most and therefore you get better leverage, better stopping performance.

So how thick are the Jag rotors that your calipers matched and were they from the front or rear? The 300ZX rear ones blueovalz mentioned are 10mm thick.

They are 290mm in diameter, 10mm thick

Believe Mike, the front rotor won't fit on the back

From whats available at my end of the planet, it looks like the most viable rear disc brake setup will involve using solid rotors. In particular, the early 300ZX 4 stud rotors, which should slip on without alteration. For those who aren't familiar, these rotors are 10mm thick, have 47mm offset and are 290mm in diameter. They are viable because I can get a set of locally used lightweight calipers which incorporate a handbrake mechanism and a 45mm piston, whereas for any thicker ventilated rotors that might fit, only old design heavy all iron calipers are available. To get to the point, has anyone had any problems with solid rotors on the rear warping after heavy use?

Fitting an adjustable proportioning valve into the rear brake circuit is, I think, supposed to reduce the tendency for the rears to initially tend to lock up. Correct me if I'm wrong, but such a proportioning valve does two things. One, it reduces the amount of pressure transferred to the rear brakes in a set proportion to the amount of pressure being applied from the master cylinder. Two, it adjusts the pressure threshold point at which the above begins to occur. Which I guess is why they are used in the rear circuit ie to counter the tendency for the smaller cylinder capacity rears to come on first. A stimulating discussion, fellow enthusiasts

Nothing as neat as your setup, Pete, I didn't know that there was such an item as that Wilwood handbrake only caliper. No, my present rear setup uses a PBR combination caliper, but that is now too small compared with the fronts. So I considered using the PBR for handbrake only duties and adding a two spot.

Thanks all for the advice Seeing that I'm committed to big fronts, the rear rotors and caliper piston will be big in diameter, too, to help balance. The present setup uses a Willwood adjustable proportioning valve in the rear circuit so that will be left as is. If there is still a problem I can try using grippier/softer pads on the rears. Scca, your 2 piston with handbrake rears should be a winner. I considered using two separate calipers on the rears, one two piston, one sliding for the handbrake only, but concluded that would be too messy and difficult to fit in.

Something just occurred to me if you have 4 piston front calipers with single piston rear calipers so as to keep the handbrake, the front/rear brake balance is going to be way out. Assuming for the sake of the argument that all the pistons front/rear are the same diameter, you will have 4 times the pressure on the front brake pads as on the rears. So having adjustable bias on the rears seems pointless. Would it be better to fit the bias adjuster into the front brake circuit in that case?

Re MoTec ECU. Mine is the basic M4 which drives sequential injection for a four cylinder engine. The M48 and M8 drive sequential for up to 8 cylinder engines. Sequential injection is desirable for smoother engine idling and drivability. While a MoTec is not the cheapest system around, it is very simple to set up and tune and will drive any ignition system. This keeps the final cost down. As an indicator of how good they are, MoTec recently won a contract with Porsche against all comers, including Bosch and other big name suppliers. I don't sell them but am a completely satisfied user

No rear roll bar is the thing to do here, too, even with a LSD. I like mine with bars front and rear. One thing I've found is that the stock '77 mounts are not strong enough, the rear ones particularly allow a lot of flex which means that the bar is not working as it should. So I use beefier aftermarket poly mount bushes and retaining brackets. Plus I've strengthened the stock chassis mounting areas, the stock rear ones being particularly weak.

Sorry for the double post, but it just occurred to me that the starter may be jammed. Try rocking the engine at the crankshaft pulley. The stuck shifter indicates that the trans may be loaded up, too. This could be caused by a jammed starter, or, perhaps by a jammed pilot bearing that, possibly, has caused the starter to jam. Anyway, best of luck.

Never done a MR2 clutch but you'd think that if the transmission fitted up ok the pilot bearing couldn't be too tight. But on the other hand if you had to pull it in using the bolts....... Then again, if its in neutral a binding pilot bearing should not stop the engine from spinning over, it will only make it difficult for the clutch to disengage? Tried disengaging the clutch when attempting to spin the engine over?

Being of the KISS ilk, things like full front to rear undertrays on a Z seem like overkill to me. If each mod you do is based on sound, aerodynamic principles, with a specific advantage in mind, the combination should work. Designing a full length undertray seems to fall outside that concept. We know that a whaletail rear spoiler with the correct slope (30 degrees?) works, same with a modest Gurney lip. A low as possible front spoiler that restricts airflow under the car, ducted to direct air where you want it to go, works. A horizontal splitter helps that process. As someone said, rake helps too. Also consider horizontal extenders parallel to and below the sills so as to reduce air exit from under the car. One problem area is the bonnet (hood to you Murricans ) so look at doing something to it so as to reduce SMOOTH airflow over it. Vents would help there and would assist cooling, just prominent enough to spoil the airflow without creating too much extra drag. See, KISS works

The only 'bad' thing I've heard about the SR20 is that the aluminium block flexes when putting out a lot of power. This claim may have been realised by Nissan when they brought out a race version for some series in Japan. That version is dry sumped and has what looks like a substantial cast iron 'sump', which is almost flat. Such a sump would assist in preventing block flex. I suppose that something similar could be fabricated.

Thanks, Mike, as you say there is not a lot of meat around the Outlaw holes, I'll helicoil the strut holes.

Truly excellent, ZR8ED, nice work, love the colour, too. A couple of querys, does the pan/undertray slope from the horizontal? And it looks like you have used some semi flexible heavy (black) strip around the front which extends below the undertray?

My preferred option would be to get one of the kits on offer but the weight of the rotors puts the airfreight cost too high. Therefore I'm adapting locally available stock rotors. A check of the Outlaw 3000 mounting holes shows that they are a bit over 11mm so maybe using a 12mm parallel reamer to open them out would be ok. Be better engineering practice to ream them rather than drill them out? Unless someone has tried this and had problems. The calipers came with Carbon Metallic 7751.80.20.04 pads, marked 'race ready', whatever that means. Are these pads ok for road and track use?

I made one up based on a design from our Zoom car mag. Basically, the air line from the turbo to the diaphragm is bled of air pressure. Using lots of suitable flexible tubing, I mounted an adjustable needle valve in the cabin. Of course an accurate boost gauge is needed to set the adjustment range, and perhaps a restrictor in the air line to reduce adjustment sensitivity. But it is never adjusted in practice, set at 15psi boost permanently. Use my right foot to govern boost

Seeing that the cost of airfreight on heavy items such as rotors from the US to here is a killer, I am in the process of adapting stock ventilated rotors and Outlaw calipers to my '77. Using 15" wheels, it looks like 292mm (about 11 1/2") diameter rotors will be max, with the calipers located on the stock lug hole centers. The Outlaw mounting hole centers match but their holes are slightly smaller than the stock holes. Seems like I have a couple of options. One is to drill out the caliper holes to match, but this may weaken the calipers too much. Another option is to drill out the stock lug holes and use inserts to re-thread them to match the caliper holes. Any comments or suggestions? If inserts are the go, what brand/type is most suitable?

quote: Originally posted by Mikelly: So I should be good pushing 42# injectors on a 500HP small block chevy right??? Man that would be a good hting if I don't have to buy another pump! Mike Don't want to rain on your parade, Mikelly, but on the advice I was given using a theoretical 520 bhp capable pump on a 500 hp engine would be pushing it, greatly. The Bosch Motorsport pump B580 152 460 is rated at 600 bhp but even that would be marginal for your application IMHO, considering that the pump pick up, fuel lines, etc would have to be perfect in order to deliver full flow. Some people use twin pumps on high HP engines but I don't know how they are set up ie in series or parallel.

See also Aerodynamics topic in Paint and Body.