Gears for 10.50's.

[Race Jace]

I plan on running the same RPM range as every one else, but just using all of four gears.

If a lower ratio is so great, then get a 1.83 gear and just use 1st and 2nd gear.

Or better yet, just run a straight drive 1:1 and just use one gear the whole track, like a rail car.

I'm sure you can get stupid in either direction.

My question may be:
What is the best number of gears for a 10-9sec car with an automatic? Not one or two obviously. Three is what 99% run, I guess. Why not four? We already have it, and it's spinning, ready to go. Gear it up for a 3-4 shift just after the eighth, and then run thru OD. Shifting at the same RPMs as everyone else, just sooner in time compaired to a "normal" geared car using 3 gears.

So, some of you thing by shortning the actual time spent in each gear, we are loosing some torque usage, or something like that? Like, the motor can't rev-up that fast?I don't feel that happening. Faster cars spend much less time in each gear but, seems to work for them. I am refering to low nine sec TRs, etc.

I too am aiming for 10.5 and better next year.

I agree it seems like 4 gears would be better but i have not tried it personally so all i can offer is what i have tried. One thing we are trying in another car i am tunning on is "getting stupid" in one direction. we are running a power glide, so yes it will only have low and 1:1. I don't know how this will work. We'll see.

I have a 200 not a 400 in my car.

also everyone says it is more streetable with the 3.42 but i drove a car not too long ago with a 200R4 and 3.73 gears and it was much funner to drive than the 3.43s. It "felt" much faster on the street because it spun the tires more, was more responsive and went through the gears faster.

Also people talk about too loose of converter making it not streetable but a loose converter makes it much more fun to drive similar to the lower gears.

this thread is very debateable. I would like to see more experiences in this area.

 

[DonnieShort]

I don't think it would be a waste of time on all TR motors. if you had a motor that made power up that high it would benifit because the converter would have less slip. I would say most of us don't but there are some.

I would love to see a comparison myself.

I was meaning that for 90% of TR owners. A comparison would be interesting though on say a low 10 high 9 car.

 

[Cheeseburger]

I bought my car with 3.73 gears in them years ago and liked them, i broke teeth off the ring gear and switched to 3.42 gears and did not like them.

I now have 3.70 gears and like them wayyyyy better then 3.42 gears.......must be my combo!

 

[John Wilde]

We have a 1.80 first gear in Chow's Power Glide and 3.70 Gears with a 29.5 Inch Tire.

1.28 - 60
5.20 @ 144 - 660
7.97 @ 175 - 1320

with some more converter tuning and droping the gears we will see 7.7 @ 180 Plus.

In addition the Outlaw Turbo Cars that run 33inch tall tires all run between 3.40 and 3.89 Gears. They make over 2000HP and go 200MPH in the 1/4.
Even the guys with 5 Speed Liberty/G-Force and Lenco Transmissions.

Why reinvent the wheel on a slower car?

 

[Race Jace]

We have a 1.80 first gear in Chow's Power Glide and 3.70 Gears with a 29.5 Inch Tire.

1.28 - 60
5.20 @ 144 - 660
7.97 @ 175 - 1320

with some more converter tuning and droping the gears we will see 7.7 @ 180 Plus.

In addition the Outlaw Turbo Cars that run 33inch tall tires all run between 3.40 and 3.89 Gears. They make over 2000HP and go 200MPH in the 1/4.
Even the guys with 5 Speed Liberty/G-Force and Lenco Transmissions.

Why reinvent the wheel on a slower car?

but i went from 26" tall tire to 28, to 30 and then to 3.23 gear with those 30" tall tires and picked up every time. ????

weird eh?

 

[John Wilde]

but i went from 26" tall tire to 28, to 30 and then to 3.23 gear with those 30" tall tires and picked up every time. ????

weird eh?

I will not argue with success my friend and you have had a lot off it.

 

[PhilM]

So is anyone here ran/run a 400 with ~3500stall and 28" tire? Im trying to figure out what's gonna happen with a lower ratio. I've heard of a lot of ppl having to pop it into OD just at the last bit to avoid overrev at the end.

Phil

 

[MAX PSI]

How about a 5.14 gear?

I run a 9" rear in my TSM car. I run the above gear. I do use all 4 gears. I usally 60' in the high 1.3's to low 1.4's. We are going to use a lower first gear sometime in the near future. (I forget what the ratio is). If you do the math a 5.14 in OD is the same as a 3.42 in drive, or real close. There are a couple advantages to this setup. I can get away with a tighter converter and it reduces the load on the drivetrain from the rearend foward. I've gone 3 seasons on the same trans. It does have all the billit parts in it.

Who knows maybe a 3.42 and 3 gears would be faster. Someday i'll find out but 9.93 on a iron headed motor ain't bad.

I guess that puts me in the 1% that don't use a 3.42

 

[got rice?]

i understand that our motors work best under load,but wouldnt putting numericaly higher gears in as we go taller with tires still be the rule of thumb like most other car? taller tires take away tork. with a taller tire on stock 3.42 gears,it would be like having numericaly lower gears in the car.

 

[BLACK6PACK]

Most people go with taller tires and keep the 3.42s to keep the rpms down in 3rd while crossing the line. If you're running 12s, stick with a 26" tire. If you're running 9-10s you need to the 28" tire at least so that you can cross the line at less than 6000 rpm.

 

[Race Jace]

I run a 9" rear 5.14...
I guess that puts me in the 1% that don't use a 3.42

wow that is cool, i would really like to drive around that car and see what it is like.

 

[MAX PSI]

wow that is cool, i would really like to drive around that car and see what it is like.

I'll be at Bowling Green this year. You will be more than welcome to take it for a spin.

When going down the track it will shift to 2nd before the 60' mark and unless you listen close you don't hear it.

 

[Blazer406]

I have always read.... turbos love load..... and make tons of torque down low... so really don't need the extra torque multiplication from a lower (numerically higher) gear. This also lessens the engines perceived load... thru extra torque multiplication....(which I think is counter-productive)....Our torque is modulated via how much boost you launch with..... IMHO... as long as you can leave on good boost... on the edge of tire slippage.... why would you need the extra torque multiplication? .... with the lower gears (i.e. 4.10's).... you probably couldn't launch on as much boost as with the higher (ie 3.42's)
(the above argument applies to running lower gears to "help it out of the hole")

The following argument applies to running the lower gears ... so you finish the 1/4 mile at the top of OD instead of D)

From an engineering point of view (as applied to a car running a 1/4 mile drag race).... looking at shifting into OD ... and running it out thru the traps.... this is less than 1:1 which means... you have to run the input shaft through some gearing... to achieve the .67:1 OD .... for every gear mesh you have... there is/are efficiency penalties due to friction in the mesh itself.... some types of gears are more efficient than others..... with that said.... I see no engineering advantage... to using all 4 gears... and finishing in OD....... as opposed to proper gearing and finishing in D... just a shade past peak RPM....

If you had some way to measure running resistance... I would bet money you could set up a test.....with and engine.... 2004R... and a 3.42 rear end..... spin it say 4800 engine RPM... in D..... ... lets just say this would equate to 120 mph for a car running a L/U converter with a 26" tire.......measure the required HP to maintain this RPM......

Now... change rear end gears to say 4.10's.... or whatever it would take to achieve 120 mph in OD at 4800 engine RPM....same tire size......bring it up to 4800 engine RPM... and measure that required HP to maintain 4800 RPM.....

I'd bet it takes more HP to maintain a steady state 120 mph with 4.10's in OD... than 3.23's in D.......

Does any of this make sense?

 

[Garycar]

The bottom line based on my testing of my 86 GN with the stock motor and cam but with ported iron heads was that the higher numerical gear set (3.90)ran esentially the same as the 3.42 but lost several mph and a just a few hundreths in et. I would always evaluate each time slip. I would look at the et difference from the 60' to the 330', from the 330' to the 660' and to the 1000' and finish line and not once did I see even an slight advantage with the 3.90 gear set including 60'. Since I drive my car several hours on the weekend weather permitting with the new bigger stage 1 motor it just doesn't make sence to me to buzz the motor on the street for no gain in the quarter mile.

 

[Blazer406]

The bottom line based on my testing of my 86 GN with the stock motor and cam but with ported iron heads was ........... it just doesn't make sence to me to buzz the motor on the street for no gain in the quarter mile.

Amen..... well said.

 

[Turbo-Archie]

Anyone ever run a 3.08 on a stocker? I would think that would make the stockers MPH more.

 

[Dominic]

I run 3.23 in my Buick with a TH400 and 28" tire, my converter is a 4500. It has good street manners and it 60's good too.

 

[Blazer406]

I run 3.23 in my Buick with a TH400 and 28" tire, my converter is a 4500. It has good street manners and it 60's good too.

Love the sig! :biggrin:

 

[VadersV6]

Ditch the IRS and throw a solid axle with 4.56's in a 99-01 cobra, and the thing will wake up beyond belief. Thats what I had. The stock 3.27's made the car feel like a yugo. But thats because the cobra has a peaky motor. It doesnt even start to pull till 4k, and you can shift over 7k. So it needs and loves the extra gearing. But the TR motor makes so much torque down low, and the powerband is so flat, that you have no need for a low gear. The idea of running 4th in the 1/4 makes no sense to me though. You end up on the opposite side of torque multiplication...more like torque division. You're just working against your own gearing, and not towards accelerating the car. OD is meant for fuel economy. Not drag racing.

 

[chevyII]

Alot of the hybrid guys are running 3.08 gears and picked up time VS stock. I think that all being equal running the trans in OD with the small clutch pack cant be good for long. If an engine has a flat torque curve like any turbo engine does try to maximize the time the engine stays in that curve. Straight from the mouth of the late great John lingenfelter.