OK. Well, picking a trans doesn't depend on the HP. It depends on the torque curve. So you need to figure out which engine you really want to go with, and stick to, and pick a trans to match up with what it puts out, and what sort of MPG and performance you want. You also need to know what tires you're going to use. Big sticky tires are going to make the shock load much higher, and so you're much more likely to break axles or a trans with them.
I agree 100 percent with what is said by dobey the engine will determine what gear ratio and how big a ratio spread is needed between gears . you wouldn't take and try using a drive train geared for a 4 cyl turbo behind a Big Block and expect it to work perfect or vice versa
Afraid I just don't get this. Yes, you can build racing ultra close ratio 6 speeds, but none of the stock 6 speeds are done that way. You've already admitted that the first gear on this trans is too low. What do you gain over a decent set of 5 speed ratios?
If you intend to drive at under 100 MPH most of the time, the 6th speed which is normally a long OD ratio, does nothing for you.
Must be some sort of hidden magic to the idea of being able to say you have a 6 speed that I am not getting.
BTW, my 1962 Triumph had a 7 speed close ratio with OD operable on 2nd, 3rd and 4th.
Originally posted by BillS: Afraid I just don't get this. Yes, you can build racing ultra close ratio 6 speeds, but none of the stock 6 speeds are done that way..
It's a shame they do it this way. I read somewhere that a C6 Z06 reaches it maximum speed in 5th, not 6th gear. The top gear is just to be able to cruise off idle basically. More weight and complexity for no reason - a CAFE-induced mutilation of a sports car. The top gear should be arranged so the engine is running at maximum power while going at maximum speed down a 10 percent grade or something.
I have no problem with a shitload of speeds if 1st gear is set to provide an appropriate amount of wheelspin on launch, top gear is chosen as per the above, and the engine is peaky enough to require 6 speeds or whatever.
(for example, I'm okay with my bikes having 27 speeds)
/rant
That said, a reason to go with a newer transmission is that even with equivalently crappy ratios, it could help you put down more average power to the wheels.
Even when manhandling my Isuzu transmission Fiero like a cheap hooker, shifts feel like they take an eternity compared to the 1999 DOHC Saturn I used to drive (that car, in my opinion, shifts like a dream).
Originally posted by pmbrunelle: It's a shame they do it this way. I read somewhere that a C6 Z06 reaches it maximum speed in 5th, not 6th gear. The top gear is just to be able to cruise off idle basically. More weight and complexity for no reason - a CAFE-induced mutilation of a sports car. The top gear should be arranged so the engine is running at maximum power while going at maximum speed down a 10 percent grade or something.
If you want a race car, buy a race car. There are very few places in the world where it's legal to drive top speed on the street. There are plenty of places where driving even the posted speed limit isn't necessarily safe, given poor road maintenance. The Z06 gears aren't special. The standard Vette, Z06 and ZR1 all have very similar gears. What you "read somewhere" and what is true, aren't always the same thing. Gear ratio, tire size, and engine speed dictate what the top speed is going to be. Nothing else matters in that equation. HP and Torque will only tell you how fast you can get to that speed, but not what that speed is. The amount of weight it takes to have that extra gear is insignificant. The benefit of having it, far outweighs the cost to have it there. A brand new stock Z06 runs 11s in 1/4 mile, and with drag radials only, can drop into the 10s. The engine also makes enough torque that you can go from 0 to 175 MPH in only 5th gear. So clearly you don't need any of the other gears in the trans.
You might as well say that street legal is a bastardization of a sports car. Might as well just put straight exhaust on it; pull everything out of the interior except the seat, steering wheel, and pedals; and stiffen the suspension all the way up with road course tires. Only then can it be a true sports car, right?
Originally posted by BillS: Afraid I just don't get this. Yes, you can build racing ultra close ratio 6 speeds, but none of the stock 6 speeds are done that way. You've already admitted that the first gear on this trans is too low. What do you gain over a decent set of 5 speed ratios?
If you intend to drive at under 100 MPH most of the time, the 6th speed which is normally a long OD ratio, does nothing for you.
Must be some sort of hidden magic to the idea of being able to say you have a 6 speed that I am not getting.
Originally posted by dobey: Gear ratio, tire size, and engine speed dictate what the top speed is going to be. Nothing else matters in that equation. HP and Torque will only tell you how fast you can get to that speed, but not what that speed is.
No. Unless you were running at redline already, or running above the maximum power RPM, you can't increase a car's top speed by making the gearing taller.
But anyway, there isn't a single car on the market that's up to my liking. I'm picky.
[This message has been edited by pmbrunelle (edited 08-01-2011).]
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12:10 AM
whitey078 Member
Posts: 39 From: austin, tx, usa Registered: May 2011
That's basically it... it applies more power to the inside rear than an open diff would.
Well, i can certainly say the ones I've used in the past can certainly do "interesting" things when one wheel hits snow and the other has traction. I know a lot of people with Quaife diff's in their Porsche, i should see if theirs is setup differently than mine... At least under-steer cause by acceleration isn't a horribly dangerous thing, i can press the gas less if that suddenly happens (but whats the fun in that)
Originally posted by pmbrunelle: No. Unless you were running at redline already, or running above the maximum power RPM, you can't increase a car's top speed by making the gearing taller.
Yes. When you shift into 6th, the RPM drops. If you bring the RPM back up, you will be going faster than you were in 5th. That's how the transmission works.
Originally posted by Archie: ... A few others' have worked on 6 speed swaps & have fabricated axle tripots & made other modifications in the axle & intermediate shaft area. They've been working on those projects for quite some time & I would guess that a couple of them might be completed. I'm sure that if they have been completed & tested, those people will speak up. AS of right now we & our customers have completed more than 40 6 speed swaps & they are all on the road.
..
This is so true. I bought my first F40 for $600 when they started to drop and most still were over $1K. I bought a spare for $450 or so. Yes Archie kit is not cheap but I have being enjoying this trany for a long time now (2006?) rather than spending time reinventing the wheel. The other great thing is that the kit is like 98% true bolt on and it works flawlessly. You only need to weld the trany mounts. Finally the best of all is that is is a brand new trany and it feels like so. I think not too many here had a Fiero brand new so they can't remember how nice a new Getrag felt shifting. I do remember that. This new one brought back the same feeling. And also something no one mentioned it is 10 times easier to bleed than a stock Fiero system. The 1st gear thing is overrated and most just repeat what they heard rather than from experience. If you can afford it and want to enjoy it quick get the kit. If you have the time then build it. Either way you will be rewarded.
------------------ Red: TPI V8 + 6-Speed White: 3800SC auto 304rwHP/366rwTQ
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11:32 AM
1fatcat Member
Posts: 1519 From: Zimmerman, Mn Registered: Dec 2010
Originally posted by dobey: Gear ratio, tire size, and engine speed dictate what the top speed is going to be. Nothing else matters in that equation.
Horsepower and aerodynamics are probably the biggest factors. Most cars don't reach their top speeds by hitting the rev limiter, they simply don't have enough power to overcome the drag. Granted, by changing the gear ratio to more closely match the top speed you might be able to get an extra few mph out of it, but it won't be very significant.
Originally posted by 1fatcat: I wanted to say something, but I have not driven one yet. It was figured to be like 2mph slower in 1st? That doesn't seem like an issue to me.
It's like 2.1 MPH difference in 1st between the F40 and 86-88 Getrag, at 6000rpm, yes.
Originally posted by Zac88GT: Horsepower and aerodynamics are probably the biggest factors. Most cars don't reach their top speeds by hitting the rev limiter, they simply don't have enough power to overcome the drag. Granted, by changing the gear ratio to more closely match the top speed you might be able to get an extra few mph out of it, but it won't be very significant.
Aerodynamics and traction are the two biggest external factors that determine if you can reach the top speed the gearing allows for, yes. There are a lot of external factors that effect that. Losing control of the car, and having it sliced in half by a telephone pole is another factor.
As far as top speed goes, everyone defines it as the maximum speed a car can go on flat terrain with no wind under its own power. If you want to consider a car's top speed the equivalent road speed it can spin its tires when jacked off the ground in top gear, go ahead...
quote
Originally posted by Alex4mula: The 1st gear thing is overrated and most just repeat what they heard rather than from experience.
One doesn't need experience with the F40 to make conclusions about it. If you drive a Fiero with an Isuzu 5-speed as I do, and you find the RPM change on the 1-2 shift irritating, then the F40 can only be worse.
Honestly, the Isuzu is pretty decent once you've gotten going. 2nd, 3rd, 4th, 5th are all pretty damn evenly spaced in a near geometric sequence. I really like it for backroad driving where I'm going fast enough to not need to dip into the oddball 1st gear.
The F40 on the other hand, starts as a wide ratio transmission, then as you go up the gears, the spacing gets closer and closer.
Isuzu, aside from the oddball first - gear changes and throttle blipping are consistent.
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02:12 PM
Will Member
Posts: 14249 From: Where you least expect me Registered: Jun 2000
It's a shame they do it this way. I read somewhere that a C6 Z06 reaches it maximum speed in 5th, not 6th gear. The top gear is just to be able to cruise off idle basically. More weight and complexity for no reason - a CAFE-induced mutilation of a sports car. The top gear should be arranged so the engine is running at maximum power while going at maximum speed down a 10 percent grade or something.
Gear for max speed is set so that the combination of the engine's power and the car's aero drag, frictional losses and tire waste heat generation combined put the top speed at the engine's peak power RPM. Odds are that's not the best ratio for fuel economy.
Go buy a ZO6, then ***** about it getting gas mileage that's better than it should be.
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02:16 PM
Gall757 Member
Posts: 10938 From: Holland, MI Registered: Jun 2010
Gear for max speed is set so that the combination of the engine's power and the car's aero drag, frictional losses and tire waste heat generation combined put the top speed at the engine's peak power RPM. Odds are that's not the best ratio for fuel economy.
Go buy a ZO6, then ***** about it getting gas mileage that's better than it should be.
Who buys a Z06 for fuel economy?
My main beef is that then you have a kludge of a shift pattern involving pressing down on a gear lever instead of three normal shift planes, all in the name of fuel economy.
[This message has been edited by pmbrunelle (edited 08-01-2011).]
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03:16 PM
Will Member
Posts: 14249 From: Where you least expect me Registered: Jun 2000
I wouldn't buy one *for* fuel economy. But it's nice that it gets 26 mpg instead of 24. Or 22 like the Viper. Or 18 like the Ferrari 458. Or 13 like the Ferrari 599 GTB.
I have no idea what you're talking about re: the shift pattern.
[This message has been edited by Will (edited 08-01-2011).]
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03:58 PM
Alex4mula Member
Posts: 7403 From: Canton, MI US Registered: Dec 1999
One doesn't need experience with the F40 to make conclusions about it. If you drive a Fiero with an Isuzu 5-speed as I do, and you find the RPM change on the 1-2 shift irritating, then the F40 can only be worse....
Well off course. Then you don't like any 5+ speed trany the Fiero can use so is moot point.
[This message has been edited by Alex4mula (edited 08-01-2011).]
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05:40 PM
Will Member
Posts: 14249 From: Where you least expect me Registered: Jun 2000
Originally posted by Alex4mula: Well off course. Then you don't like any 5+ speed trany the Fiero can use so is moot point.
Regardless of my personal desires, the irritating 1-2 RPM drop is still a valid point worth mentioning for someone else who may be considering drivetrain options. It's actually a pretty common complaint about the Isuzu here on PFF.
quote
Originally posted by Will:
I wouldn't buy one *for* fuel economy. But it's nice that it gets 26 mpg instead of 24. Or 22 like the Viper. Or 18 like the Ferrari 458. Or 13 like the Ferrari 599 GTB.
I have no idea what you're talking about re: the shift pattern.
Having to press down on the shifter to get into reverse, or having some sort of lockout, solenoid, whatever. Anything more complicated than simply either allowing the lever to self-center with the springs or slamming the lever off to one side. The H-pattern works nicely with three shift planes. More than three, less so...
Why VW would sell 5-speeds with a messed up reverse gear engagement absolutely boggles me.
(if the engine is peaky enough to require 6 speeds though, then fine)
It is true that the fuel economy is nice. I can see that side of the coin. But I'm minimalistic. If I had money to burn, I'd probably be driving a Series 1 Lotus Elise. The Fiero is more cost-effective though. Maybe I'd think differently if my Fiero were a daily driver.
[This message has been edited by pmbrunelle (edited 08-01-2011).]
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09:47 PM
Aug 2nd, 2011
Will Member
Posts: 14249 From: Where you least expect me Registered: Jun 2000
Having to press down on the shifter to get into reverse, or having some sort of lockout, solenoid, whatever. Anything more complicated than simply either allowing the lever to self-center with the springs or slamming the lever off to one side. The H-pattern works nicely with three shift planes. More than three, less so...
Why VW would sell 5-speeds with a messed up reverse gear engagement absolutely boggles me.
Would you like some cheese with your whine?
BMW puts reverse to the left of first and "blocks it" with simply a stiffer preload spring. Still four gates on a five speed... works just fine. I learned to drive in a Datsun with Saginaw 4 speed and C2 Corvette shifter. External linkage is where it's at. That transmission had a T-handle to pull up to get into reverse, which was to the left of first. That wasn't a big deal. It didn't have any preload springs *at all*. It was by far the most badass shifting setup I've worked with.
Originally posted by pmbrunelle: Having to press down on the shifter to get into reverse, or having some sort of lockout, solenoid, whatever. Anything more complicated than simply either allowing the lever to self-center with the springs or slamming the lever off to one side. The H-pattern works nicely with three shift planes. More than three, less so...
I don't know what you're complaining about exactly, but you don't have to press down on the shifter in the G6/Saab for the F40. It has a collar around the shifter that you pull up, to shift into reverse. Pretty much the same as was on a 4 speed Corvette in 1969, but with a smoother shifting trans. Of course, using the 4 speed Fiero shifter modified to be able to shift into all the gears, doesn't have this collar. I'm not sure how that feels. I'll be making custom short shifters for my cars, built like the newer GM shifters, but designed to fit and mount in the Fiero correctly.
Also, I haven't seen anyone complain about having to 'press down' on the shifter to get into reverse, for their F40 swap into a Fiero.
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09:43 AM
Alex4mula Member
Posts: 7403 From: Canton, MI US Registered: Dec 1999
I like my F40, my only 2 complaints are the ratio's between 1st and 2nd and that it's a noisy box. I was the 1st 2.8+6speed, now 3400 block. As for 1st being too high, I'm using bigger tires in the back so it's the same as the getrag with stock tires.
That's because you don't if you use the modified Fiero shifter. You just push left a little harder.
That's what I presumed happened with it. I'm not using that shifter, and haven't driven a Fiero with modified 4 speed shifter and F40, so I didn't want to assert that in fact didn't happen. But I can say that I haven't seen anyone complain about it.
In fact, I don't know anything that requires you to 'press down' on the shifter to go in reverse. Am interested to see one that does though.
I've driven lots of cars that require you to push down on the shifter to get into reverse. It's designed that way to help prevent the driver from accidentally trying to enguage reverse at high speeds...I think?
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12:06 PM
PFF
System Bot
qwikgta Member
Posts: 4669 From: Virginia Beach, VA Registered: Jan 2001
I admit, I have not read each post in this thread, but i thought I'd chime in.
Last November I went up to Machesney Park and had Archie, Rob and Chris install a new LS376 in my 88 coupe. I wanted the 6 speed, but the extra $5500 ($500 trans, $1200 LSD, $500 cryo, $3500 kit, + misc parts) was too much for my budget. I bought a "rebuilt" 1994 Getrag 282 5-spd off a member here on Pennocks. Archie told me he'd install it if I wanted to but cautioned me about putting a used trans in the car. He has (had) a pile of old 5 speed trans from other cars. I listened to what everyone said, and in the end I went with the 282.
I wish I could do it all over again. I'd spend the extra for the F40.
It has leaked, fixed, leaked again and just been a bad deal from the start. I run at about 2600-2700 rpm on the highway and my milage is about 20 mpg in this car.
I'll admit, I was suckered from the get-go, and the trans I got was not what I was told, but that is hindsight. In the end I wish every time I drive the car that I had went with the F40.
My cradle has been modified for this trans, and the amount of work to do the F40 now would cost a small fortune. I'd still need the original $5500 plus I'd have to get a new 88 cradle, modify it for the F40, modify the driverside frame rail, get new mounts and and it would have been so much better to have it done back in November.
If your thinking about doing the F40, do it. If not, make sure you build the best 5 speed you can, make sure you get what you pay for.
I've driven lots of cars that require you to push down on the shifter to get into reverse. It's designed that way to help prevent the driver from accidentally trying to engage reverse at high speeds...I think?
strangely, the only time I've had this was when reverse is on the left, when its on the right side it's either no protection, or like in my vette, you cant even push the shifter over far enough when moving at all.
And to all the comments about not needing 6'th gear cause 5'th is a higher top speed (and that was a correct quote for corvettes, and also many other cars). the highest gear is for cruising not performance. I'm not big on mileage on my kit-car, but one thing that will be nice, if I'm going a long distance on the highway, having a gear where the engine isn't at some high rpm making a bunch of noise for hours. 6'th gear in my vette has always been about "OK I'm at the speed i want to be, now lets just stay there and try not to fall asleep from boredom on the highway). If i didn't do that and tried to amuse myself for hours with it,,, I'd be in jail by now.
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03:38 PM
whitey078 Member
Posts: 39 From: austin, tx, usa Registered: May 2011
Originally posted by qwikgta: My cradle has been modified for this trans, and the amount of work to do the F40 now would cost a small fortune. I'd still need the original $5500 plus I'd have to get a new 88 cradle, modify it for the F40, modify the driver-side frame rail, get new mounts and and it would have been so much better to have it done back in November. Rob
Just curious, but why woudl you need a new cradle? The Archie video for the f40 shows him changing the 5-speed getrag that's on a v8 to the f-40 and doesn't modify the cradle (aside form welding on mounts that which wont require anythign new except for the supplied pieces of metal. According to the video, SOME cars need to slightly dent the driver-side frame rail, but I'm not sure that I'd consider that beating it with a hammer to get another 1-2 millimeters over a very small area a real modification. I'll admit that i haven't put my engine and trans in yet, but i've watched both that video, and the lsx video many many times, as well as done the real frame modifications on the passenger side for the lsx engine. with the kit and trans, this really isn't a massive undertaking if you have the tools.
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04:34 PM
Will Member
Posts: 14249 From: Where you least expect me Registered: Jun 2000
I wouldn't buy one *for* fuel economy. But it's nice that it gets 26 mpg instead of 24. Or 22 like the Viper. Or 18 like the Ferrari 458. Or 13 like the Ferrari 599 GTB.
I have no idea what you're talking about re: the shift pattern.
A Viper that gets 22 MPG ?
[This message has been edited by weaselbeak (edited 08-02-2011).]
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04:52 PM
whitey078 Member
Posts: 39 From: austin, tx, usa Registered: May 2011
Originally posted by weaselbeak: A Viper that gets 22 MPG ?
My friend gets 26 mpg in his dynoed 505 rwhp (+300 shot of nitrous) viper on the highway. It turns about 1150 RPM at 70+ mph in 6th gear, 60 mph in 1st gear... 10.80's in the 1/4. Around town is another story. He can't keep his foot out of it!!! If you have the gearing and torque with low throttle input, you will have high mileage. Look at the 8000 lbs diesel pickups getting low 20's on the highway. http://www.youtube.com/watch?v=eGT3qJ1DurI
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05:36 PM
Will Member
Posts: 14249 From: Where you least expect me Registered: Jun 2000
Diesels get good mileage because they're unthrottled. They don't have the low load pumping losses that gasoline engines have. Also because they're unthrottled, they have higher cylinder pressures at low load, which gives them a higher thermal efficiency. Lower internal losses + higher thermal efficiency = MUCH better fuel economy than gasoline.
But a basic Corvette can touch 30 mpg on the highway if carefully driven.
[This message has been edited by Will (edited 08-02-2011).]
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07:10 PM
qwikgta Member
Posts: 4669 From: Virginia Beach, VA Registered: Jan 2001
Just curious, but why woudl you need a new cradle? The Archie video for the f40 shows him changing the 5-speed getrag that's on a v8 to the f-40 and doesn't modify the cradle (aside form welding on mounts that which wont require anythign new except for the supplied pieces of metal. According to the video, SOME cars need to slightly dent the driver-side frame rail, but I'm not sure that I'd consider that beating it with a hammer to get another 1-2 millimeters over a very small area a real modification. I'll admit that i haven't put my engine and trans in yet, but i've watched both that video, and the lsx video many many times, as well as done the real frame modifications on the passenger side for the lsx engine. with the kit and trans, this really isn't a massive undertaking if you have the tools.
Yea, I guess, I powedercoated it and the mounts for the 282 are welded on now, so I guess the "modify" part of my statement is just that, cutting, welding, painting. Maybe not that big of a deal. As for the driverside frame rail, my concern is that when they mounted my motor/trans, it was put in place for the LS/282 combo. The motor mounts and such were welded in place for that setup. Im worried that if I remove the 282 and install the F40, the LS/F40 will be in the wrong place to use the motor mounts as they are now. So now im cutting/welding all new mounts, moving all the stuff over, even if its a 1/2 inch or so, now im doing a lot of cut/welding on my powedercoated setup. Again, maybe not enough of a issue to do this someday, but I will have to do some additional research, and talk with Archie about it.
