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Datsun Brakes??


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:D:roll: OK - I'm not too sure I like being referred to as car #2 here. I usually had a bunch of cars behind me which generally made me car #1. Let's not discuss why so many cars were behind me :oops::lol: - oh yeah - BRAKES - or lack thereof. I also will have to add the tires because they didn't help a lot compared to what the other cars were running. Bottom line, at 3,100 lbs the brakes just don't hold up without me being perfect and the maintenance being perfect - neither of which is going to happen. Look at it this way - for the safety of all the other cars & drivers on the track it would be best if I had better brakes. I nearly ate the back end of both the Lotus and the RX8 because I was catching them - and then catching them too fast when they braked and I couldn't even come close to matching them. Their cars were lower, wider, lighter than mine. They had wider, better tires and they had 4 wheel disks, vented, and ABS - and I was keeping up with them. Actually I was overtaking them until my brakes faded away. I have video of the Z repeatedly closing the gap in the straights and then losing it going into the corners. My speed through the corners was actually pretty close to many of the other cars. I just lost it having to brake so early and, in some cases, not being able to accellerate to even higher speeds because of the condition of the brakes. I would have really eatenthem on the oval if I'd had more confidence in my ability to get stopped. I could easily carried another 15-20 mph by moving a bit higher and using 4th gear instead of shifting from 3rd to 5th. I just couldn't afford to be close to anyone coming into the hairpin turn into the infield.
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Phantom,

 

I had similar issues with my 240Z on a recent track day in March at Summit Point Raceway. I have stock 240Z brakes with new Porterfield R4S pads up front (probably not fully seated) and stock rears with green stuff shoes, silicone brake fluid, stainless braided lines and the brakes were adjusted and bled before the event.

 

The first 2 sessions were ok but sessions 3 and 4 I noticed considerable brake fade towards the end of the 20 minute sessions. By the last 5 minutes of session 4 I had almost no brakes at all.

 

In the first 2 sessions I was able to carry 110-115MPH by the end of the main straight and still brake in time for the turn. By the 4th session I had to keep it down to 90-100MPH to be able to brake in time and on the last lap I probably only hit 80-85MPH as I was scared of running into the wall of tires. All this with the L28.

 

I will also need to upgrade my brakes once the LS1 goes in.

 

Let us know which big brake system you decide to go with. For your type of car, I agree with Gary. I would rather have too much brakes than not enough. Especially if you plan to add a supercharger in the future. The unsprung weight doesn't matter as much with a multi purpose car like yours.

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John, what is Thunderhill lap time? I may get down there in a couple months as part of the All Datsun Meet in Shasta. Being in Oregon, I'm stuck with Portland Int'l, or a long trip to T-Hill, Sears or Laguna....all in the plan for next year! :-D

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Thunderhill full track including Cyclone - 2:06.295 (ROD's best - 2:00.0xx)

Willow Springs big track - 1:33:908 (ROD's best - 1:28.2xx)

Buttonwillow 13CCW - 02:03.521 (ROD's best 1:55.1xx)

Buttonwillow 13CW - 02:05.601 (ROD's best 1:58.xxx)

Cal Speedway - 01:55.134

Street of Willow - ?

Sears Point - 1:52.868 (ROD's best 1:48.1xxx)

Laguna Seca - 1:44.812

 

Good luck guys!

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Sounds OK to me Savage, but I'm in the middle of a huge rebuild right now (gets bigger every day--while I'm at it syndrome) so I'd probably be looking at late fall to early spring for a timetable.

 

I think I can take that Buttonwillow time 13 CW time, probably the CCW as well. That's a track I'm familiar with, and I did a 2:11 when it was 105*, I had just installed Mikunis (it was like 2 weeks before the autox vid that I posted before), and I was running out of brakes. The float levels in the carbs were all wrong and it was starving on right hand turns. I thought that if I could have pulled my head out of my butt that day, the car was capable of a 2.09 despite the brakes.

 

Drop the temp 30*, allot me my extra ~50 hp that I've built up, and big brakes, a little diet. Yeah, I'll be ready for that one when I get back to CA.

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Beating the ITS record at the track I usually run (CMP) has become a personal goal for me. On used Kuhmo's, I can consistently run 2-3 seconds off the record. This fall at the time trials, I'm gonna put on some fresh Hoosiers or Goodyears and see what happens.

 

Of course, I might just spin out faster than I normally do.

 

John

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I'm not saying ITS cars don't turn good lap times, they just don't get it done with power. I don't know if you have ever been in a high HP Z on a long straight. Anything other than GT1's. Again I'm talking about speed at the braking zone. ITS cars may carry a little more speed through a corner but now way do they use the brakes as long. The track record for an ITS car at Firebird is 1.07:4. It has held that as long as I can remember. That is not the norm though. The average would be lucky to break the 1.10's with a tail wind. Mine is a 1.05:7. I run used slicks and lack the time it takes to set it up to get every last second out of it. I can run the at the ITS all time record all day long and never think twice about brake fade. An ITS car does carry a little more speed through the turns but I will pass any ITS car like it's running on 4 cylinders down the long straight and have 30 mph before turnn 1. It may carry 5mph more through a turn but it doesn't have to brake as long either. That's how they can get Datsun brakes to work. If I had a way to put up some of the in car tape I would.

 

 

IT cars don't carry the same speed into the braking point as 300+ rwhp Z, not even close.

 

I don't think anyone can make such an absolute statement. Remember, speed at the end of the straight is a COMBINATION of acceleration rate, acceleration time, and exit speed from the previous corner.

 

If ITS car #1 hits the corner apex at 90 mph and V8 Z #2 apexes at 70 mph, car 1 has two advantages at the start. The first is that car 1 is generally able to get on the gas sooner so it has more time to accelerate and car 1 also started the acceleration run from a higher speed. The speed difference at the end of the straight won't be anywhere near as great as most people think 'cuz most folks think in terms of a drag race heads up start.

 

And we can't use the "all things being equal" arguement because I have yet to hear of a V8 (or any hybrid) Z match the ITS lap record at any of the tracks I race on.

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After reading a couple posts here I don't feel too bad in some respects. If you guys were experiencing brake fade during 20 minute sessions think what the 30 minute sessions were doing to my car. 50% more time!

In other respects, though, I don't feel so good. I went through the brakes last night with the following observations.

Front brakes obviously had seen some very high temperatures - the rotors were blue and the pads were half gone and looking pretty rough. Also have grooves in the rotors I didn't have last week. Not serious but not good.

Here's the really bad part - the rear drums look great. No obvious signs of overheating at all. Pretty obvious they weren't working as hard as they should have been and the fronts were carrying more than their share of the load.

Bled the brakes thoroughly last night and they are better today (drivable) but not what they should be. May have to spend a little more time on them if they don't straighten up in the next couple days.

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The track record for an ITS car at Firebird is 1.07:4. It has held that as long as I can remember. That is not the norm though. The average would be lucky to break the 1.10's with a tail wind. Mine is a 1.05:7.

 

There we have it! Finally, a HybridZ that can beat an ITS car on a track.

 

I don't know if you have ever been in a high HP Z on a long straight.

 

Yup, the Rusty Old Datsun is at 138 at the end of the front straight at WSIR and at 143 in turn 8.

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Guest Anonymous

After spending years on the track in my Lt-1 240-z I can say with out a doubt, It's the driver. Generally speaking, those IT guys can drive circles around me. I bet one of those guys in my car would walk away from any other IT car out there. Now if I could just learn to drive.........

 

Mark

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I adjusted my rear drums last night and gained a lot of overall braking ability from 15 minutes of playing around. They don't suck, they just need to be in good shape and well adjusted! (as john has stated)

 

This discussion has not really touched on how important quality tires are to the overall braking of the car either. It doesn't matter how good your brakes are if your tires suck!

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