I have a 4 spd myself and I've been looking at the different tranmissions. It looks like all of the final drive ratios for the V6s are 3.65 or 3.61. Not much of a difference. For long distance travelling I like to cruise from 80-95 mph. With my 4 spd my rpms look high enough to make me worried and my mpg drops significantly.

Long trips take longer when you can only cruise at 65-70 mph instead of 80-95 mph. My Dodge Stealth spoiled me for high speed cruising. 90 mph is just 3000 rpms. I'm tempted to bolt up a Isuzu but I've seen a lot of posts about how weak the Isuzus are.

Are there any other transmissions that have a final drive ratio close to 3.0 or maybe a transmission rebuild gear kit that has taller gears?

My 88 V6 5 Speed (Getrag) is at about 3100 RPM at 90 mph with 245/40/17 rear tires. I've done a lot of highway driving and noticed that I seem to get very consistent and similar mileage anywhere from 70-90 mph average speed; I don't notice increased fuel economy until I get to the sub-70 mph cruising. To give you an idea of what I mean with cruising done at 55 mph I'd usually get about 29 mpg, and with cruising at 90 mph I'd get about 25-26 mpg.

Of the five speeds, I believe the Isuzu has the lowest final drive ratio...at 90 mph it would be closer to 3000 rpm instead of the Getrag's 3150.

Bryce
88 GT

Just get a 5-spd. Either Getrag or Izusu.
The 4-spd has a 4th gear of 1.00 But the 5-spd has a 5th gear of .76 The final drive isn't the only thing that affects RPM it's the actual gear. As for Izusu strength, Archie uses them with V-8's and doesn't have a problem with them.

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[This message has been edited by Oreif (edited 06-12-2003).]

I've got an isuzu in my coupe, from a '96 sunfire, with a 3.35:1 FD. 90mph is about 3,000 rpm 3rd gear tops out somewhere over 100

Main problem is, it won't bolt up to the stock fiero engine. But I would think if you got a Fiero isuzu you could swap either the bellhousing or the final drive over.

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1988 Quad 4 Coupe 5 speed click for more pics
1986 GT 5 speed
AOL: LastMinuteBastrd AIM: SavedbyJebus

There was a rare 4 speed in '84 with a 3.32 FD.

The 3.65 and 4.10 Muncies have 0.81 4th gears. The 3.32 Muncie has a 0.73 4th gear.

The Getrag has a 3.61 FD with 0.72 5th gear.

The Isuzu used in Fieros has a 3.35 FD with 0.74 5th gear.

Overall, the Isuzu and 3.32 Muncie have the tallest top gears and are approximately the same. The Muncie may have an immeasureably small gas mileage advantage because it has one less meshing pair of gears and theoretically should have less drivetrain loss, but you probably won't be able to measure it.

Using 3150 rpm at 90 mph with the Getrag as a benchmark the Isuzu would be 3005 rpm at 90 mph and the economy 4 speed would be 2932 rpm at 90 mph. The economy 4 speed is the lowest ratio at a 2.42 actual drive ratio. The Isuzu is 2.48 and the Getrag is 2.60. Going from a Getrag to the economy 4 speed yeilds only a 218 rpm drop.

quote Originally posted by Rodney: Using 3150 rpm at 90 mph with the Getrag as a benchmark the Isuzu would be 3005 rpm at 90 mph and the economy 4 speed would be 2932 rpm at 90 mph. The economy 4 speed is the lowest ratio at a 2.42 actual drive ratio. The Isuzu is 2.48 and the Getrag is 2.60. Going from a Getrag to the economy 4 speed yeilds only a 218 rpm drop.

Thats interesting to know. I thought the isuzu was a bigger drop then that, But I havent drivin one to actually find out.

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I wish I had a place that I could "cruise" at 90MPH. The State troopers dont like it when I cruise over 70

The easy way is to just get bigger tires...but then your speedometer would be off.

-FD

Too bad, there is a 3.32 4 speed in the 1984 econo coupe in my driveway, I'd gladly trade it for the 3.65 tranny but I am in Gander Newfoundland which makes things a little difficult.

Ira

Hi revs are not bad! My 95 integra gsr revs at 4k at 80 miles an hour and I get 28-33 mpg with it. hehe

quote Originally posted by Rodney: Isuzu would be 3005 rpm at 90 mph

That sounds about right, I have the 88 5 speed Isuzu.
I don't remember what my 86 isuzu 5 speed cranked out but I know it was different.

The TH125 in my corsica cranks a mind bending 2300 rpm at 80 mph.

For the best of both worlds the 4T60 automatics offer a compromise between having a good FDR for accceleration and one for highway cruising. They are available in a wide number of different ratios but it must be remembered that the lower the RPM's at high speed, the slower your car will be on the street and "off the line". Don't expect to win as many street races as before.

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quote Originally posted by FXRseen: Hi revs are not bad! My 95 integra gsr revs at 4k at 80 miles an hour and I get 28-33 mpg with it. hehe

My 87 Celica has the same exact final ratio in 5th. 4000 rpms for 80 mph. There is a big difference though.

My Fiero is a 6 cylinder pushrod engine that isn't meant for high revs. My Celica is a DOHC 4 cylinder that revs all the way to 7250 rpms without thinking twice. 2.8L engine as opposed to a 2.0L engine. I'll bet that My Celica's 2L engine burns the same or less gas at 4000 rpms than my 2.8L Fiero engine at 3000 rpms. Another comparisons is that my Celica is rated at 135 hp and 125 ft/lb of torque. My Fiero is rated at 135 hp and 170 ft/lb of torque. Higher torque means I should be able to run higher speeds with much less rpms.

There are a lot of 5 speeds that I can pull from wrecked cars in my area. The only thing is that the final drive ratios between my current 4 spd and 5 spd are nearly identicle. 3.61 Vs 3.65 is hardly enough of a difference to justify doing a transmission swap.

quote Originally posted by voyagerspe: I wish I had a place that I could "cruise" at 90MPH. The State troopers dont like it when I cruise over 70

I've been in NY before. Crusing speed there was like 60mph lol. I'n the toronto area its sick. Crusing speed is normally about 120kph, all the way up to 150 sometimes.

I've passed enough cops at 140, and they don't seem to mind.

[This message has been edited by ManiMack (edited 06-12-2003).]

quote Originally posted by Dennis LaGrua: but it must be remembered that the lower the RPM's at high speed, the slower your car will be on the street and "off the line". Don't expect to win as many street races as before.

Not when you can hold the gear for a lot longer than the other guy I've found holding first until almost 30 and second till around 65 helps out a bit

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1988 Quad 4 Coupe 5 speed click for more pics
1986 GT 5 speed
AOL: LastMinuteBastrd AIM: SavedbyJebus

While on the subject, any good auto transmissions to use for the same purpose? I've heard you can use Caddy transmissions that have overdrive, but I don't really know...in addition, what years/makes/models of cars can you get these transmissions from? ease of installation? Any modification required?

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'86 Pontiac Fiero SE 2.8
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'88 Ford T-Bird 2.3 Turbo Coupe
'67 Chevrolet K10

quote Originally posted by Standard: Not when you can hold the gear for a lot longer than the other guy I've found holding first until almost 30 and second till around 65 helps out a bit

What ratios do you have in that thing? I hit about 33 in 1st and almost 60 in 2nd.