Deception

Just letting everyone know that I pulled the pushrods and checked them, everything was good. There was a small bend in a few rods but only about 1mm, barely noticeable. Buttoned the car up and took her for a quick ride everything seems fine to me.

I think I'll take American_HP's advise and buy a lotto ticket today cause I can't believe that nothing broke.

2GOFAST

The rev limiter does not help in a missed shift. It is there to help on the way up to keep you from overreving with the gas pedal. If you downshift instead of upshift the mechanical linkages will overrev your engine regardless of the rev limiter.

vjjack04

What 'mechanical linkages'? The rev limiter is within the ECM software. Anytime you engine revs beyond the 'limit' the revs are electronically cut. I am not sure that as a previous poster stated 'when you miss a shift you go directly to 7k...

BlackZ06

We are discussing a manual (RPO MM6 or M12) transmission .... there is no "line pressure" to "kill" (the gear has been selected by the driver using a mechanical linkage between the shift lever and the shift forks in the transmission) ..... and killing fuel pressure if you selecct 2nd gear at 100 MPH won't make any difference .... when your foot comes off that clutch pedal the weight and momentum of the car is going to spin the engine to at least 2,000 RPM over redline in this example .....

The incorrect selection of a gear with a manual transmission is an inherent risk .... on upshifts or downshifts ..... you can do serious damage selecting the wrong gear ..... caveat emptor ....

BlackZ06

Again, we are talking a MANUAL transmission ....

Let's take simple example .... redline is 5000 RPM and .....

1st gear redline is 20 MPH
2nd gear redline is 40 MPH
3rd gear redline is 60 MPH

(SIMPLE example ..... meant to illustrate the discussion)

Driver accelerates the car in first gear to redline .... then shifts to second gear and at redline (40 MPH) intends to shift up to third gear .....

First, let's assume that instead of shifting up ... the driver stays in 2nd gear with the accelerator pedal to the floor. The PCM (Powertrain Control Module) will use the built in rev limiter to keep the engine at 5000 RPM. The driver can keep the pedal floored all day long and (at least theoretically) the engine won't go over 5000 RPM. In the "olden days" before engine management computers I could damage my engine by simply staying on the accelerator until the engine blew up because it had no protection against such an over rev.

Now, to continue the example, the driver shifts ..... BUT .... instead of selecting third gear the driver mistakenly selects first gear .....

Well .... when the driver releases the clutch ... in this example (40 MPH shift into first) the engine speed will immediately rise to close to 10,000 RPM ...... I say "close to" because the drive wheel tires will probably lose grip with the road before the engine speed can get that high ... plus there will be some "braking" effect as the drivetrain tries to accelerate to match the 40 MPH speed .....

Manual transmissions use MECHANICAL linkages for the driver to select a gear. The only "electrical" connections to my manual tranny are for things like transmission fluid temperature sensor ...... my PCM has NO CONTROL over the gearbox ...... with enough brute force I can basically select ANY gear in the gearbox at ANY speed. I may have to fight the synchronizers ..... but it can be done.

billla

...and you put them back in?

Warp Factor

What you're after could probably be done a couple of different ways.

(A) The computer applies the rear brakes when the fuel shut-off fails to take care of the over-rev condition.
The downside is that you probably lose control and crash. With an over-revved engine, people rarely die.

(B) The computer monitors the gear selected, compares that with road speed, and a solenoid doesn't allow the clutch to engage when there's a mismatch. Downside is greater complexity and more to go wrong. Instead of column lock threads, we'll have "My clutch won't engage" threads.

Question: How much intervention do you want in a sports car?

XtremeVette

iam learning and yes completely agree since line pressures won't work on a manual transmission. We will have to do it electronically. I would say again, it probably is not difficult just takes more programming to be done to get all the systems in sync. I would compare it to a sophisticated CAGS (skip shift 1-4) program only running in reverse. Basically the car would know, hey stupid what your asking me to do....NOPE I aint gonna do it. This is the wrong gear selection. Thus it will lock out the gear on you and prevent you from going there. I know this already applies to reverse. This is why under no circumstance can you accidentally shift into reverse by accidentally going from sixth back to fifth. The car has lock outs on that. hmmmm I think we are onto something that should go into GM's thought box for their next manual transmission. Automatic gear lock out selection so no over reving can occur. Each gear would have a maximum redline and would not allow you to pop into that gear if the car knew you were going to fast for it.

PerrinPhantomZ06

I completely agree, how many more electronic controllers (or any controllers) do we need on these cars. Its bad enough when you try and row a gear and then find you left traction controll on and looked like a fool. When driving a manual car that has any power (or any manual car) you need to hook up the plug n play left foot right hand brain monitor... These are free and only require the proper use of mind over matter.

Left foot never leaves the clutch untill brain senses right hand in proper gear. If you cant feel your proper gear then you need to pull over, turn the motor off and gently practice which gear goes where and when.

Not flaming anybody, especially not the original poster but user error shouldnt be the means of a new controller system. Its just not necessary.

I feel bad for those nissan techs...Just wait untill people start tapping into the electronics on those AWD and ECU systems of the new GTR which are all controlled by computers. Your gonna see 9 Technicians all standing around the mechanic bay scratching there heads

BlackZ06

Yeah, you could do that (raising price of car and complexity ... which could affect reliability) ..... but you also have taken away "driver control" ..... and I like to be in control ..... (several ex-girlfriends and wives have noticed this fault .... )

Let me give you an example of where your system would drive me nuts ....

Look at Laguna Seca .... come out of turn 11 and accelerate flat out through turn 1 to turn 2 .....

http://www.laguna-seca.com/pages/Track_Map

You will be close to redline in 4th gear (120+ MPH) as you approach turn 2 ..... but turn 2 is so tight that you need to exit it in 2nd gear .....

So I approach turn 2 in 4th gear ..... as I begin braking for the turn, I shift from 4th to 2nd (Right foot braking - Left foot on clutch pedal) .... as my speed falls within the range of second gear I "blip" the accelerator pedal to raise engine speed and allow the clutch to engage.

I'm now in the correct gear to "throttle steer" through turn 2 .......

Your system would require me, for some split few seconds, to choose 3rd gear ..... a complete waste of time .....

To me, driving a car is like piloting a boat .... YOU are responsible for the outcome of your trip.

If you're out in the middle of the ocean and your GPS fails ... you had better have the charts, tools (sextant and chronometer) and skills to get to a safe harbor ..... it is your responsibility.

If you're on a race track or on city streets, quit relying on "nanny" aids ..... you bought a Corvette ... freakin drive it ..... or sell it because you don't have the skills or cojones to drive it.

msuc5vette

Since you have a blower, you might have been better to take the opportunity to upgrade the push rods while you had them out.

If you didn't fully engage the clutch, i.e. just drop the clutch back in, you probably noticed the RPMs being forced up and let off before you spun the engine way too fast anyway.

Deception

I may in the not-to-distant future, it would be easy enough anyways. It probably wouldn't take me more than an hour since I've already taken it apart once...


As far as I know the bends were completely normal, that's how small it was. I mean spinning them on a glass table, the end would move less then 1 mm. If I saw any markings or anything else abnormal I would have replaced them, no questions asked.

I thought about the same thing, it would be very easy to implement in a new car design. However, I think it's because my ego is bruised that I'm thinking like this. I made a mistake and am now petrified that it will happen again, in this instance an electronic control would be perfect. Practice makes perfect I suppose.

billla

ANY bend is not normal. Additionally, if they are deformed at all - they're weakened.

IMHO, I'd put a new set on your todo list - and observe a 5500 or lower redline until they're in.

But that's just one guy's opinion

bassman12350

Wow! Gotta thank God for this "less serious" outcome. Gotta agree with BillA though. Any deformity of the rods is a sign they need to be replaced.

Bill Dearborn

I have known several previous members from when the forum first started who over revved their engines when downshifting going into a turn during an HPDE. Some of the engines even survived the initial incident but grenaded at a subsequent track event.

Bill

02gt350

revved my stock ls1 to 7200 all the time...no issues. 6200 is gay. plenty more there without failure

but who knows what you hit if you downshifted..maybe 8000, never know. but if it drives fine, leave it. if the valvetrain gets loud or is louder, you have bent a pushrod, which is a really cheap and quick fix...your not gonna have any PVC issues that is IF your block is still all stock

Deception

Thanks guys. I'll definitely order some pushrods tomorrow. Who knows, they may have been bent by the previous owner as I know that he tracked the car a lot. Either way I'd rather be safe then sorry.

I may do a compression sanity check anyways. How likely is it that I bent a valve but don't hear any additional noise? I don't have the tools for a compression check so I'd have to take it somewhere.

billla

Might want to consider a valve spring swap and rocker rebuild as part of an overall valvetrain update "while you're in there".

IMHO, I wouldn't worry about checking the CR...a leakdown test might tell you something, but I'd suspect you'd see a code and/or noise and performance issues if there was anything worth worrying about.

Chuck A

so i also need to say i have done that on my vette, i was going nice speed when in fact i was supposed to go into fourth , i went into second , man those rpms, went crazy, so you guys think it should be allrigh then, huh, i was in second for 2-3 seconds tops, let me know, sorry about the hijack, but figured its the same basic question

02gt350

listen to yoru valvetrain.......is it more noisey than usual?

check your pushrods...20 min job. re-TQ rockers to 22 ft lbs.