Auto or Manual?
Discussion
Hi JT,
Thanks for the tip.
I did check for that as I had read about it before, but the symptoms I had were strange in that the car started and ran fine for a couple of minutes, and then started coughing and banging and running rich before cutting out. It didn't backfire prior to playing up. But just to be sure I checked all of the vacuum connections that I could see.
I think it may have something to do with when the engine switches over to closed loop mode. I've started the car several times since and it will run OK for a couple of minutes and then suddenly goes chuggety chug, running very rich for a while before dying. I suspect that something in the ECM is faulty.
But just to be sure I will recheck all the vacuum lines. Of course it could be one under the plenum, but I won't pull the plenum until I've tried swapping out the ECM.
Thanks for the tip.
I did check for that as I had read about it before, but the symptoms I had were strange in that the car started and ran fine for a couple of minutes, and then started coughing and banging and running rich before cutting out. It didn't backfire prior to playing up. But just to be sure I checked all of the vacuum connections that I could see. I think it may have something to do with when the engine switches over to closed loop mode. I've started the car several times since and it will run OK for a couple of minutes and then suddenly goes chuggety chug, running very rich for a while before dying. I suspect that something in the ECM is faulty.
But just to be sure I will recheck all the vacuum lines. Of course it could be one under the plenum, but I won't pull the plenum until I've tried swapping out the ECM.
Is the Auto truly a 4 speed auto???
Confused here..
Yesterday I counted 5 changes (was not accelerating fast, quite slow actually) - I was sure of it... (Well it dropped back to 1200RPM 4 times!)
I was sure that it changed in to second at 20, 3rd at about 30, 4th at 40ish and again it dropped back to 1200 RPM at 50.
Does it have some sort of overdrive?
Confused here..
Yesterday I counted 5 changes (was not accelerating fast, quite slow actually) - I was sure of it... (Well it dropped back to 1200RPM 4 times!)
I was sure that it changed in to second at 20, 3rd at about 30, 4th at 40ish and again it dropped back to 1200 RPM at 50.
Does it have some sort of overdrive?
For driving and cornering - manual.
You just can't get the delicacy of gear shifts in an auto and the damn box keeps changing up when you want it to change down. The gaps between ratios is quite severe and the autos come with higher gearing in the back axle. Manual allows selection of the right gear, feathering of the clutch, a clutch if it oversteers and generally more punting ability.
For drag racing and highway use - auto.
The auto is usually faster up the strip because you're watching the tacho on a manual and getting the shift just right can be messy without a shift light. The 2nd-3rd shift can also go wrong. Auto is foot hard down and wait for the finish line as the car changes up at the optimum revs. Also on the highway, when you kick down, the auto, though slow to start with, will pick the lowest gear it possibly can which is often one lower than you might risk in a manual although you've still got the four ratios to slow you and the higher rear axle ratio giving ground to the manual.
Manual is more fun though. Auto is better for just being lazy, cruising and steering. Learning to provoke the kickdown is useful to making swift progress but you still get that upshift when braking.
Cost is a very serious consideration. Autos will last forever if not abused, with regular fluid changes but clutches are danged expensive to replace and you're without the car while it's being done.
Do what I do - have both.
You just can't get the delicacy of gear shifts in an auto and the damn box keeps changing up when you want it to change down. The gaps between ratios is quite severe and the autos come with higher gearing in the back axle. Manual allows selection of the right gear, feathering of the clutch, a clutch if it oversteers and generally more punting ability.
For drag racing and highway use - auto.
The auto is usually faster up the strip because you're watching the tacho on a manual and getting the shift just right can be messy without a shift light. The 2nd-3rd shift can also go wrong. Auto is foot hard down and wait for the finish line as the car changes up at the optimum revs. Also on the highway, when you kick down, the auto, though slow to start with, will pick the lowest gear it possibly can which is often one lower than you might risk in a manual although you've still got the four ratios to slow you and the higher rear axle ratio giving ground to the manual.
Manual is more fun though. Auto is better for just being lazy, cruising and steering. Learning to provoke the kickdown is useful to making swift progress but you still get that upshift when braking.
Cost is a very serious consideration. Autos will last forever if not abused, with regular fluid changes but clutches are danged expensive to replace and you're without the car while it's being done.
Do what I do - have both.
gsmcoverage said:
Is the Auto truly a 4 speed???
Yesterday I counted 5 changes .... Does it have some sort of overdrive?
This one surprised me when I first got the Vette because the final shift that comes around 47 mph in gentle driving feels exactly the same as the gear changes. However this is just the lock-up clutch kicking in to save fuel and is not another ratio even though it looks on the rev counter and feels in the seat of the pants just like one.
So far as I know lock-up only ever happens in 4th gear although others may know more about it.
The main difference in gear ratios manual/auto is the heavy reliance the auto places on 2nd gear which tops out at 100 mph on the speedo! (I think the official GM figure is 92 mph) But given that stock manuals force a 1st to 4th shift under normal driving this is not surprising. Most or all manual owners disable CAGS though. The auto is marginally slower off the line but once it's rolling in 2nd gear there's very little that can stay with it including manual Vetts. The big TVRs are quicker than all Vetts but if you have one behind you on the track then under full throttle you can sometimes (depending on the driver) see them drop back at gear changes while the auto Vette keeps on pulling to the red line and then power shifts to third for more of the same!
LuS1fer said:
snip...
The auto is usually faster up the strip because you're watching the tacho on a manual and getting the shift just right can be messy without a shift light. The 2nd-3rd shift can also go wrong. Auto is foot hard down and wait for the finish line as the car changes up at the optimum revs. ...snip
Interesting. GM quotes a faster 0-60 time for the manual box
yellowshark454 said:
snip...
The auto is usually faster up the strip because you're watching the tacho on a manual and getting the shift just right can be messy without a shift light. The 2nd-3rd shift can also go wrong. Auto is foot hard down and wait for the finish line as the car changes up at the optimum revs. ...snip
Absolutely right and in the right hands, the manual will be faster. When I say usually, I mean rolling off the line and flooring it involves little scope for getting it wrong. The manual box is not a fast box and it's very easy to miss a change. Also it's very hard to watch the tach and the track and get the change spot on at the maximum revs whereas in the auto, the computer does it for you. Finally, the manual technique involves dumping the clutch and in the US, power-shifting is common ie you don't lift the throttle when you change. Americans will get the fastest time possible by any means possible, whatever the cost to the car (which isn't theirs). At RWYB's, I see autos running quickly and consistently but manuals tend to be slower in practice unless you've got a very good driver who knows what he's doing. So in tgheory, the manual is faster, in practice, it's often slower and less consistent.
I know because I've beaten a Viper. In theory, that could never happen.
Interesting. GM quotes a faster 0-60 time for the manual box
Can I be controversial? You guys with late model 5 and 6 speed manual boxes won't be able to match the 1/4 mile times of a early Muncie close ratio 4 speed.
If you look at the ratios available on your 5 and 6 speed boxes they have a 1st gear that is far lower than a c/r Muncie and overdrive ratio on fifth and sixth gear and biased for mpg and low rpm touring.
In effect you guys have a first gear that will light the tyres, a second gear that is slightly higher than the first gear of the Muncie.A properly set-up and driven 4 c/r speed will outperform an automatic going through the traps in 4th gear.
If you look at the ratios available on your 5 and 6 speed boxes they have a 1st gear that is far lower than a c/r Muncie and overdrive ratio on fifth and sixth gear and biased for mpg and low rpm touring.
In effect you guys have a first gear that will light the tyres, a second gear that is slightly higher than the first gear of the Muncie.A properly set-up and driven 4 c/r speed will outperform an automatic going through the traps in 4th gear.
LuS1fer said:
snip.... So in tgheory, the manual is faster, in practice, it's often slower and less consistent.
Can't argue with all of that. I would suggest though that the HUD makes a difference in covering the track and the revs simultaneously. Hurst shifters are very popular in the States. Anyone got experience of these? Personally I think my replacement sexy gear knob makes a difference but yup still clunky. A manual box has never been one of Chevy's strong points in my view.
The aftermarket shifters seem to mount directly off the gearbox (rather than the transmission tunnel) I guess a directly shifter mounted is in theory better but you will have to accept modifying the centre console to allow the gearstick to move side to side with torque reaction.
Yes I agree the Muncie shift operation is inferior to some period gearboxes. I had a Ford toploader box behind a 428 big block in a mid 60's Galaxie.The upwards shift action on this was sufficiently good enough to allow full throttle upshifts. Just try doing that with a Muncie !
Yes I agree the Muncie shift operation is inferior to some period gearboxes. I had a Ford toploader box behind a 428 big block in a mid 60's Galaxie.The upwards shift action on this was sufficiently good enough to allow full throttle upshifts. Just try doing that with a Muncie !
Please excuse me stepping back a bit further in history... back to pre-89 cars.
Looking at the old Car & Driver articles and tests the auto's vs manuals (specifically it was either 85 or 86 cars, the differences were 0-60 time of 5.7 seconds for the auto and 6.0 seconds for the manual. Quarter mile times were also similarly better for the auto. Top end speeds were the same, and you suffered a 2mpg penalty for the auto.
In the real world I have done an officially timed 5.73sec to 60 with mine - not bad for a 120k 18 year old car. Traffic light grand prix's - often I have the joy of watching other drivers seemedly select reverse as they change gear. Agreed that auto is tricky in the wet, although I didn't notice any issue on the one track day I've done, could drift and control the car easy.
Anyway I waffle on. I prefer the earlier hydraulic box 'feel,' and think (from camparison with the 4L60 electronic box fitted to later Corvetes and Firebirds)it responds more instantaneousely. I think it may have a shift improver kit in it, it shifts lovely and firmly, and it seems to know what I want to do most of the time. But the L98 motor is more of a low down pull motor - LT1's and on that were bilt with more RPM capability are perhaps more suited to a manual.
Sorry - I'll stop now...
Looking at the old Car & Driver articles and tests the auto's vs manuals (specifically it was either 85 or 86 cars, the differences were 0-60 time of 5.7 seconds for the auto and 6.0 seconds for the manual. Quarter mile times were also similarly better for the auto. Top end speeds were the same, and you suffered a 2mpg penalty for the auto.
In the real world I have done an officially timed 5.73sec to 60 with mine - not bad for a 120k 18 year old car. Traffic light grand prix's - often I have the joy of watching other drivers seemedly select reverse as they change gear. Agreed that auto is tricky in the wet, although I didn't notice any issue on the one track day I've done, could drift and control the car easy.
Anyway I waffle on. I prefer the earlier hydraulic box 'feel,' and think (from camparison with the 4L60 electronic box fitted to later Corvetes and Firebirds)it responds more instantaneousely. I think it may have a shift improver kit in it, it shifts lovely and firmly, and it seems to know what I want to do most of the time. But the L98 motor is more of a low down pull motor - LT1's and on that were bilt with more RPM capability are perhaps more suited to a manual.
Sorry - I'll stop now...
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