let me start by saying i have about 455 miles on a new clutch, RB light steel flywheel, and pressure plate. well last night i took off in first an then i gunned it and i got up to about 35 mph in first. befor i got the new flywheel i could esily hit 40 in first. whats the deal? also my car makes a worring noise at idle when the clutch is not depresed. any one have any idea on what that could be?

 

could be your throw out bearing. i know mine made that noise at first. it eventually went away. as for lowering the top speed in gear. well i could be wrong , just a guess. but you now have a lighter flywheel. Since you have less wieght carrying the momentium. it will hit the max faster. with cars you normally have draw backs. use a lighter flywheel. you have a quicker from a start but you loose top end speed. each mod you do will most likely have a draw backs.

 

You are wrong.
Lighter flywheels does not lower top speed, it actually increase it. It's common sense. Can you spend a 10lb wheel faster or 20lbs wheel faster?

With a lighter flywheel, you can spin it faster because it takes less force to spin.
Momentum on a flywheel comes handy ONLY when you are launching.

Momentum = mass x velocity. With as lighter flywheel, just launch it at a higher RPM to get the same momentum.

Anyhoo, to the original poster, your limited top speed could be from something grinding... check it out before your clutch/drivetrain gets destoryed.

PD

 

the whirring noise sounds like a pilot bearing. i'm guessing it wasn't changed. it's good to change whenever you get a new clutch installed.

the problem regarding speed also wouldn't be the problem of the flywheel/clutch...unless for some reason it is slipping at high revs.

 

you too sir are wrong.

simple answer, there should be no change in top speed in the gear. why? because the e-shaft and trans. input shaft act as one piece while the clutch is engaged, this would not affect the speed of the input shaft. the only reason it would lower the overall top spead of any gear would be if the clutch was slipping.

the lighter flywheel would change the launch characteristics and acceleration but not the gear ratios.

tire pressure and changing tire size can affect the speed of the gear, did you happen to change the tires at the same time with a smaller profile tire?

 

In the case of 1st gear, momentum only affects acceleration and deceleration. The top speed in the gear is determined by the engine redline and the driveline gear ratios and associated losses. The only way the clutch could affect the top speed is if it is slipping or there is something mechanically wrong creating drag, which would create more slip or less efficiency than with the original flywheel setup.

The only time momentum would affect top speed is when the engine's power available is close to the power required for the car to maintain that speed, and the momentum difference makes enough difference in power available that the speed is affected. This would normally only come into play in the higher gears where weight and drag become more of a speed limitation than gearing.

The reduced speed problem could be a false perception, but it may be good to take a look around when you have the system apart when troubleshooting the noise problem.

The noise sounds like a problem with the pilot bearing. A bad throw-out bearing usually starts making a chirping noise when the clutch is depressed during a gear change before it wears enough to start making a whirring noise at idle.

 

In theory, you should have a higher top speed at the top gear given the fact that our cars are HP and Drag limited. With less power required to turn the flywheel, more power is used the turn the wheels, which translate into a higher top speed. Marginal as it is, it is still an increase.

 

top speed yes, slightly. in first? RPM to speed correlation will be the same regardless of the clutch/flywheel used.


this thread is regarding 1st gear not top speed, it has gotten a bit off the mark.

 

If your car is drag limited in 1st gear, then it has major hp issues. Even when my friend's NA engine was running on 1 rotor it could still go over 35mph.

 

lighter flywheels allow the engine to rev faster.. i dont think the top speed would change, it would just get there quicker, which could lower the speed when taking off quick.. so maybe in some cases you would have a lower top speed?

 

it's not going to reduce your top speed, it's not affecting the final drive ratio in any way shape or form. X RPM in Y gear will give the exact same MPH as it did before the flywheel change, assuming the clutch is not slipping.

It is possible that his speedo is just lagging behind if he's basing this observation on speedometer glances while accelerating.

 

i got the piolt bearing changed when i got al the rest changed could the noise just be the bearing breaking in? the noise stops when i press the clutch in thought i would mention that.

 

Yes most likely it is. I had the same problem when I put in my ACT stuff, i also put in a lighweight flywheel. Yet I didnt have any speed issues with it. The car just went up the rpms faster.

 

it does go through the rpms faster and it does accelerate faster. but it hits redline and ill be going slower than before i ever changed the flywheel

 

also is it normal for a clutch as it breaks in to become a little less grabby. when i first got it it was REALLY grabby but now its not as bad but it still has bite just not as much

 

Redline could not be changed via a clutch. Gear ratios are not changed by a clutch. If you were 40mph@7K rpm then it should be the same now. There has to be a mistake

 

I bet this is what is happening. Now that you rev through first gear more quickly, the speedometer lags behind, more than it did before. Try just cruising in first gear at redline -- you will find that it is exactly the same speed that you would have seen with your old flywheel.

You guys should all know that changing a flywheel does not change your gear ratios at all, which means your speed in each gear will be exactly the same that it was before.

And while a light flywheel will allow you to accelerate more quickly (especially in low gears; the effect is not significant in high gears), it won't change your top speed. You aren't accelerating at all when you reach your top speed, so the reduced inertia from your light flywheel has zero effect. And in reality, you will be accelerating so slowly in top gear that the flywheel wouldn't make a significant difference in your rate of acceleration in that gear anyway.

-Max

 

You tell 'em max

 

i will check the redline how you said maxcooper i never thought that the spedo could be laging behind

 

i think its the speedo lagging...

in my protege, in neutral the tach lags behind (reved it to the limiter (6750RPM)) but the tach was still only at 6000RPM when it hit the limiter.... but the tach caught up after...

i just think its the same thing with the speedo happening imo

 

FYI:
If you have whirring noise without depressing the clutch then you got problems prolly with the bearings inside the tranny or your pilot bearing. Throw out bearing noise will usually occur when pedal is depressed

 

Ya know the older I get the more I find my Speedo lagging.












Sorry

 

<Nitpick>Since the speedometer takes its input from the transmission (on all the rx-7's I know of), it doesn't change indication with tire size. Sure the speed has changed, but speed indicated on the speedometer doesn't.. </Nitpick>

 

On my last NA tranny, a similar issue turned out to be a tranny bearings issue

 

Clutch pedal was probably never adjusted and is causing the t/o to press against the PP(which is the whirring), which could have killed the clutch already. However, there seems to be a few things going on here.

A clutch CAN effect speed. And I've never heard of a mechanical speedometer that would lag noticably. If you can only top out 1st gear at 35 vs 45 prior, and your RPM's are the same either the following happened:
You changed Tires/wheels/pressure/etc
Changed the speedo gear/etc
The clutch is slipping
Your tranny or speedo are fuqt