"Lift-off oversteer

[JMortensen]

Just out of curiosity, what does it take to be a good design? If a GT3 cup car is 20 seconds faster around a road course than your Z when its all done, is the GT3 still a bad design?

 

I used to work at a Porsche shop and poke fun at the customers who poked fun at my Datsun. I'd tell them that driving a Porsche is like throwing a dart backwards, or that I'd rather have 6 in the front than 6 in the rear, but realistically, there are a hell of a lot of Porsches that are faster than my Z will likely ever be.

 

For axles, I don't think you're going to do better than Chequered Flag and that's about $700 if I recall. Then you can buy adapters for CVs from me or Joe [me] and if you get my short shafts you'll be into it $1500. That should be enough to move the weak link in the chain elsewhere.

Edited March 29, 2012 by JMortensen

[johnc]

... it is successful because of the people who drive them. Not because the car. Why are f1 cars not rr then?

 

Rules.

 

What's funny is that you'll hear these arguments about how ill handling a Porsche (or any FWD car) is on the Internet and in car magazines. But you do not hear these arguments at a race track. Racers know that on any given day pretty much any driver/car combination can win. And the Porsche 911 has so consistently won races since the SWB version came out in 1964 that its the winninest race car in history. That says a helluva lot about the success of the design. Its the ultimate test.

 

FYI... I was just out at the SCCA Double regional at Buttonwillow and two ex LBGP Pro Celebrity Toyota Celica's beat two T1 C5 Corvettes in a 30 minute race. The folks on the Internet and in the car magazines will say that can't happen, but it does - all the time. Its nothing remarkable.

[vega]

Just out of curiosity, what does it take to be a good design? If a GT3 cup car is 20 seconds faster around a road course than your Z when its all done, is the GT3 still a bad design?

 

I used to work at a Porsche shop and poke fun at the customers who poked fun at my Datsun. I'd tell them that driving a Porsche is like throwing a dart backwards, or that I'd rather have 6 in the front than 6 in the rear, but realistically, there are a hell of a lot of Porsches that are faster than my Z will likely ever be.

 

For axles, I don't think you're going to do better than Chequered Flag and that's about $700 if I recall. Then you can buy adapters for CVs from me or Joe [me] and if you get my short shafts you'll be into it $1500. That should be enough to move the weak link in the chain elsewhere.

 

I am not ragging on porsche. I love the cars, fun to drive if you know how to drive them. It takes a very very skilled driver to drive them well. I have driven 911s (on the street not on the track unfortunately)and I have driven caymans and 944s etc. I personally really enjoy the cayman s, and the 944s, and the 928 (when more power is added) after driving the 911 I think sticking the same driver (if we are talking open class rules here) in a different more midship design the later of the two should out do the 911 from my person experience thus far. Btw when I personally think 911 I think of the traditional rear engine rear wheel drive car. I am not talking about the awd 911 cars, I suppose I could be more clear. I can see how an awd 911 can and would out handle a traditional 2 wheel powertrain, that is, IF the electronics are properly controlled etc. I have yet to have the pleasure of driving an awd 911, from what I have been told by other racers they are amazing.

[vega]

Rules.

 

What's funny is that you'll hear these arguments about how ill handling a Porsche (or any FWD car) is on the Internet and in car magazines. But you do not hear these arguments at a race track. Racers know that on any given day pretty much any driver/car combination can win. And the Porsche 911 has so consistently won races since the SWB version came out in 1964 that its the winninest race car in history. That says a helluva lot about the success of the design. Its the ultimate test.

 

FYI... I was just out at the SCCA Double regional at Buttonwillow and two ex LBGP Pro Celebrity Toyota Celica's beat two T1 C5 Corvettes in a 30 minute race. The folks on the Internet and in the car magazines will say that can't happen, but it does - all the time. Its nothing remarkable.

 

How much does the celica weigh? how much the corvette weigh? The corvette still using that oh so amazing leaf spring suspension? I can see the celica taking a c5. Power to weight, less weight in general, a good driver, the power curve for the track, etc. Also I own and drive daily a em1 civic si with an sirII motor with sticky street tires, pretty stock suspension for an em1. disconnected the front links. I can take clover leafs in mn at about 65 before a spin out (sand forgiving). Fwd is not as horrible as people think if the steering shaft is low, the suspension is a wishbone style strut like the em1 etc.

 

From a design perspective, a vehicle with the bias of weight behind the rear wheels and being rear wheel drive, is NOT the optimum for a high performance vehicle. If this was the best of the best why would F1 cars be all rear midship engine rear wheel drive cars? Why is it that they are the only performance cars with the engine behind the rear wheels that has had any success? Porsche has done an excellent job tuning the suspension on a layout that in physics and (again) from a design perspective doesn't really work that well for optimum performance. BUT that does not change the fact that if Porsche were to focus on a car (the cayman) as they should more that the cayman would blow the doors off and run circles around the 911 around the track, which it does from what I have been told by Porsche racers around mn.

 

If I were do build my own car up from scratch it would end up being almost identical in every way to the cayman r. There are very few flaws in that design. The biggest flaw and advantage is the boxer motor. Boxer motors have an issue with their oiling system (from my own and other people I have worked with - experience) this can cause premature wear on the bearings. The advantage of a boxer motor is the ability to place the motor low in a vehicle cause the center of gravity to go lower with it. The power curve of a boxer is fantastic when tuning correctly it can make the tq through out the rpm range, up and down. I think a displacement of about 3.8 litters with a compression of 13:1 with direct ignition and injection with vvt and a variable intake and two cams above each cylinder head would be advantageous to such a motor. I have come to really like the new diesel designs myself and would like to see a boxer diesel motor if possible.

 

Even internally at the *** this same argument is being made. Porsche vs audi vs lambo. Us discussing this topic really is about as useless as a 80 pound girl at a green treat wrack at a lumber yard.

[vega]

Anyhow, back on topic. In your opinions at what tq level do you fellas agree upon that the axles start snapping on these cars?

[vega]

Also thanks for the heads up to Chequered Flag the adapter flanges for the cv conversion (280zx or z31) are 400 plus shipping. The billet axles they have are 700. I am not sure if I need the adapter kit though. I am running a 78 280z with a r200 so I think i just need the billet axles.

[vega]

So I have been doing some further reading and I saw your amazing post.

http://forums.hybridz.org/index.php?showtopic=50499

 

So let me just make sure I have this right. Using the cv adapter can I not use the entire shaft of the z31 300zx turbo? Why would I still need to use stub axles if the z31 300zx turbo cvs are the correct length? I feel like I am missing something here.

[vega]

Entire z31 cv axle set.

http://www.classiczcars.com/forums/attachment.php?attachmentid=31263&d=1250938463

[JMortensen]

I don't have a torque number for failures on these things. I can say that it seems that the flange failures are more common than twisting the shaft off. Maybe some of the drag racers could answer that question better than I can.

 

The splined shaft part of the CV that you linked to fits into the diff. The 4 bolt part bolts to the CV adapter, which is the companion flange to the stub axle. So you still need stub axles, and you still need the companion flange. Stock Z31T axles are too long and the bind can cause diff failures.

 

Here's the M2 group buy for the CV adapter (I have these in stock right now):

http://forums.hybridz.org/index.php/topic/105514-m2-cv-adapter-for-z31t-cv-280z-stub-axle/

 

Here's the M2 group buy for the short axles (on order, should be available in 3-4 weeks):

http://forums.hybridz.org/index.php/topic/105510-m2-z31t-short-shafts-group-buy-2/

 

This is an install thread of the short shafts:

http://forums.hybridz.org/index.php/topic/103391-z31-axle-swap-r200-clsd-m2-differentials/

 

And here is the discussion that led to M2 making these parts:

http://forums.hybridz.org/index.php/topic/103391-z31-axle-swap-r200-clsd-m2-differentials/

[260DET]

Just out of curiosity, what does it take to be a good design? If a GT3 cup car is 20 seconds faster around a road course than your Z when its all done, is the GT3 still a bad design?

 

I used to work at a Porsche shop and poke fun at the customers who poked fun at my Datsun. I'd tell them that driving a Porsche is like throwing a dart backwards, or that I'd rather have 6 in the front than 6 in the rear, but realistically, there are a hell of a lot of Porsches that are faster than my Z will likely ever be.

 

For axles, I don't think you're going to do better than Chequered Flag and that's about $700 if I recall. Then you can buy adapters for CVs from me or Joe [me] and if you get my short shafts you'll be into it $1500. That should be enough to move the weak link in the chain elsewhere.

 

Time attack at my local circuit (Lakeside, look it up) well driven Porsche cup car gets comprehensively owned by two Evo's and not for the first time. Bang for buck P cars don't rate on the club scene. An the Evo that came second is a daily driver with air con etc. http://www.natsoft.com.au/cgi-bin/results.cgi?11/11/2023.LAKE.P4

Edited March 30, 2012 by 260DET

[260DET]

Rules.

 

What's funny is that you'll hear these arguments about how ill handling a Porsche (or any FWD car) is on the Internet and in car magazines. But you do not hear these arguments at a race track. Racers know that on any given day pretty much any driver/car combination can win. And the Porsche 911 has so consistently won races since the SWB version came out in 1964 that its the winninest race car in history. That says a helluva lot about the success of the design. Its the ultimate test.

 

..................................

 

If Porsche is the winningest car in history then that is due to their focus on doing so and the lack of constant and similarly dedicated opposition, P sink or swim according to their race results, no other car company does, Ford showed what could be done by a casual multinational car co with the GT40. Geez, S30's given a level playing field can smack Porkers down, really they are pretty ordinary cars in a lot of ways with some pretty ordinary engineering.

[Sideways]

The corvette still using that oh so amazing leaf spring suspension?

 

Apologies- The batteries have died in my sarcasm detector. Were you taking a stab at the "leaf-spring" suspension employed by the C5 corvette?

 

 

If this was the best of the best why would F1 cars be all rear midship engine rear wheel drive cars

 

So can we further extrapolate your logic used here (or at least the logic you have thus implied here) and deduce that open-wheel design is better than close wheeled design for racing? I mean, if it wasnt- Why would F1 do it, right?

Edited March 30, 2012 by Sideways

[vega]

I don't have a torque number for failures on these things. I can say that it seems that the flange failures are more common than twisting the shaft off. Maybe some of the drag racers could answer that question better than I can.

 

The splined shaft part of the CV that you linked to fits into the diff. The 4 bolt part bolts to the CV adapter, which is the companion flange to the stub axle. So you still need stub axles, and you still need the companion flange. Stock Z31T axles are too long and the bind can cause diff failures.

 

Here's the M2 group buy for the CV adapter (I have these in stock right now):

http://forums.hybridz.org/index.php/topic/105514-m2-cv-adapter-for-z31t-cv-280z-stub-axle/

 

Here's the M2 group buy for the short axles (on order, should be available in 3-4 weeks):

http://forums.hybridz.org/index.php/topic/105510-m2-z31t-short-shafts-group-buy-2/

 

This is an install thread of the short shafts:

http://forums.hybridz.org/index.php/topic/103391-z31-axle-swap-r200-clsd-m2-differentials/

 

And here is the discussion that led to M2 making these parts:

http://forums.hybridz.org/index.php/topic/103391-z31-axle-swap-r200-clsd-m2-differentials/

 

You say in that original thread that the z31 axles are the correct size. Then it appears that later on people found they bind, from what you are giving me, because they are a tad too long. Couldn't one just take the z31t shaft to a local machinist and have them shortened? That seams that it would be significantly cheaper. For some reason I was thinking the splined end was the end that went to the hub not the diff. So is the spline the correct count from the z31t to the longnose r200 I have in my 78' manual 280? In other words would it slide right in as it appears?

 

Also just want to get this straight. You are saying the companion flange the stub axle goes into is the part that usually goes bad instead of the stub axle itself unless we are talking about a car running say 10s with drag radials? I will not be running drag radials or slicks of any kind ever. To me it sounds like I can use 280z stub axles (the ones I have) with the cv conversion and be just fine. Is this correct?

Edited March 30, 2012 by vega

[vega]

Apologies- The batteries have died in my sarcasm detector. Were you taking a stab at the "leaf-spring" suspension employed by the C5 corvette?

 

 

 

 

So can we further extrapolate your logic used here (or at least the logic you have thus implied here) and deduce that open-wheel design is better than close wheeled design for racing? I mean, if it wasnt- Why would F1 do it, right?

 

If you guys are so desperate to have a discussion about this open a different thread please.

[vega]

I finally got a chance to go look under the z at my shop a minute ago. I get what you are saying now. I think I am going to have to go in on the next group buy. I just spent 1800 in parts this last month. Got to wait a few weeks before I have another 700 again to blow.

 

The woman just got mono this last week so she is out of work for a while. Her case is fairly serious. We thought it was the flu but the fevers just wouldn't quit. I took her to the hospital on Wednesday this week. It came fast and hard when it did come. Neither of us make a salary we are both hourly and commission so this kind of blows. We were told it could last up to a month.

 

I am going to end up using my stub axles with your flange/cv adapter with the shorter shafts you sell. Probably going to be May until I purchase them from you. I will keep you updated. Thanks for the patience btw.

[johnc]

Hope your wife/girlfriend gets better soon.

[JMortensen]

You say in that original thread that the z31 axles are the correct size. Then it appears that later on people found they bind, from what you are giving me, because they are a tad too long. Couldn't one just take the z31t shaft to a local machinist and have them shortened? That seams that it would be significantly cheaper. For some reason I was thinking the splined end was the end that went to the hub not the diff. So is the spline the correct count from the z31t to the longnose r200 I have in my 78' manual 280? In other words would it slide right in as it appears?

That original statement that the Z31 shafts are the right length is a mistake. They do bind. I covered why you can't just cut the splines further down the shaft in the other thread, but I'll post that picture here again too. The problem is that the CV shaft tapers down from the splined area, so there is no metal there to cut. Yes, the Z31T shafts plug right into a standard 29 spline open R200 out of a 280Z. The only exception is the 88 SS version which came with a VLSD that had 30 splines.

 

Also just want to get this straight. You are saying the companion flange the stub axle goes into is the part that usually goes bad instead of the stub axle itself unless we are talking about a car running say 10s with drag radials? I will not be running drag radials or slicks of any kind ever. To me it sounds like I can use 280z stub axles (the ones I have) with the cv conversion and be just fine. Is this correct?

The companion flange is not the part that normally breaks. It's usually the stub axle flange where the wheel studs are, or the end of the stub axle shears off where the splines are. You might very well be fine with stock 280Z stub axles and the CV conversion. If you're drag racing part of the game is shock loading the axles. Obviously that's worse if you're on slicks, but somebody who drag races could give you a better idea of when you might expect to have a problem.

 

Best wishes for your woman. I've had mono, it's not fun.

Edited March 30, 2012 by JMortensen

[vega]

Much appreciated to the both of you in reference to my girl. She was shaking Wednesday morning she is a bit better now. We got her on some kind of anti viral they gave her. She has had continuing fevers up and they break up and they break. She has stay below 102 for the past two days thus far. Albeit she has gone as low as 97 which is odd to me. The highest she was at was 104.7

 

--------------------

 

JMortensen

 

I must have missed the section on why they can't be cut. I won't be drag racing unless its on the street on STREET sticky tires (non drag radial type) I probably wont hook worth crap. I assume that if the tires are breaking loose this is a bit easier on the parts. These tires are more for high speed cornering. The tires are 320AA rated so I don't really expect them to hook, but they should hold grip around a corner for the track if I don't goose it too soon.

 

The initial reason for the post is I haven't experience said "lift off oversteer" in any of the cars I've owned aside my old fiero (which is prone to it as well too short of a wheel base for the location of the motor and weight of motor/trans in my opinion). The civic si I own if I want to take a tight turn not only do I have to use the Scandinavian flick, I also have to flutter between full throttle and the clutch as well as trail break. In the datsun I haven't had to do that at all, just using a controlled slide is what I have found to work best for me thus far, which is WAY easier to control than the SI. I was taught how to drive from Chris Gordan who has done every Rally America event for the past 10 or more years. So my style of driving has come mostly from that. I also did participate at Nemadji trail with Chris Gordon and Dan Adamson back in 2010 in the G2 class. Just to give you guys my background.

 

I will be driving the car on the street, on the highway mostly. Also as far as the track I will be at most of the time, I will be going to Brainerd International Raceway in MN. Just a track day weekend racer with the local import club. Nothing serious, I would only be racing against myself really. I am not really concerned about the other people and their records etc. The reason I am doing the v8 swap is I am tired of getting smoked by the darn civic and mustangs around down - on the highway. I figure that I will have plenty of power with the 327 I am using. That and the extra power will really help around the track as well. I have ran it with the L6 and really was disappointed. This is also coming from a guy who had used to own a fiero with a 383 blown sbc.

 

You mentioned "shock loading the axles" can you fill me in on this a bit?

[JMortensen]

Drag racing starts/dropping the clutch puts a huge load on the axles.

[vega]

That makes sense to me.