can a 373 gear be used with a auto trans

[stacks1]

every 373 gear I view to buy shows with manual trans.is that not a good gear with auto trans?

 

[Huskerman]

Should work ok.....drivability would depend on what auto tranny your are going to use with it and how those gear ratios would work in relation to the 3:73's. It would work ok you just might not be happy with the cars rpm's at cruise.......Hib or some others know more I'm sure.

 

[BigJimZ16]

every 373 gear I view to buy shows with manual trans.is that not a good gear with auto trans?

Will probably need a Torque Converter change with a higher stall speed to be drivable.

 

[aboatguy]

You won't need a stall converter for your gear swap. Higher stall converters are to let the engine get into the power band easier (usually in conjunction with a head cam swap since you lose some low end). Your gear swap helps the engine get into the power band. I don't know if the VSS and speedo gear combo you need to correct the speedometer are available. If the gear-set you are looking at says manual only it may be for a Dana 44 and not the Dana 36 that your A4 equipped C4 came with. Ring & Pinion Gear Sets - Dana 36 Ring & Pinion Gear Sets Make sure the gearset you get is proper for the carrier in your rear IE 2 series carrier if you have 2.59s in you car now. mike

 

[Hib Halverson]

Can 3.73s be used in a C4 automatic.
By all means

Would you want to do it?
Probably not.

On the street you'll see a significant loss in fuel economy. Also, since the first gear ratio in the 4-spd auto is 3.06, you're final drive ratio is going to be really low. The car will spin the tires constantly.

 

[stacks1]

appreciate the responses. I have a 2000 stall ,trans go s/s shift kit, zpack gears.383 stroker ported heads runners plenum 58 mm t.b long headers 3in borla exhaust.just want a little more off the line..what gear would I have 1990 conv? what gear would I want..week end driver for me and the wife to cruise the big city of Memphis tn.

 

[stacks1]

maybe after spending $16,000 I thought it would be faster..:confused

 

[Hib Halverson]

maybe after spending $16,000 I thought it would be faster..:confused

For street high-performance, you can go wrong with the stock performance axle ratio for automatics which is 3.07:1.

 

[aboatguy]

appreciate the responses. I have a 2000 stall ,trans go s/s shift kit, zpack gears.383 stroker ported heads runners plenum 58 mm t.b long headers 3in borla exhaust.just want a little more off the line..what gear would I have 1990 conv? what gear would I want..week end driver for me and the wife to cruise the big city of Memphis tn.

With all of that work..... You should look into a D44 swap Good news is the majority of C4 D-44s are loaded with 3.45s which in my experience are pretty darn good on the street. Mike

 

[Dog House]

With all of that work..... You should look into a D44 swap Good news is the majority of C4 D-44s are loaded with 3.45s which in my experience are pretty darn good on the street. Mike

Glad to here this. That's exactly what I'm in the process of now. That and an engine swap.

 

[WhalePirot]

I didn't like the 3.73s for reasons stated here. Now, I wish my car had 3.07s or 3.36s versus the 3.54, as wheelspin upon launch is a continual problem; power is not.

I had the entire rear unit cryo treated for hardness with no breakage problems... so far. Those who redo the cars with plenty more power are wise to save for rear end work and possible tranny/driveline.

 

[John Robinson]

Here is the formula for figuring the rpm for the different gear ratio

RPM=mph x final drive ratio x gear ratio x 336
________________________________________
26

So lets use the final drive ratio and gear ratiofor my 93 for this example

75 x .70 x 2.59 x 336 = 456876 Divided by 26 = 1752 RPM

Now all you have to do is plug in what ever ration you want

Using a 3.73 instead of a 2.59 will have the following results at 75 MPH theRPM will be 2530 or 778 RPM more per mile.

You can simulate this by dropping the trans into a lower gearthat puts the rpm in that range at 75 to see if you would like that on theroad.

As others have said the MPG and the traction will be big issues but this wouldgive a lot more low end performance without touching the engine.

If the engine has any miles on it this will increase the piston wear factor byabout 7% because of the increase in what is called feet per minute. This is based on using the stock gear ratios in the transmission and only changing the final gear ratio.

 

[vetteoz]

383ported heads runners plenum what gear would I want..week end driver for me and the wife to cruise .

With any form of long runner (TPI) intake you are rev limited and the bigger the engine then the lower down the restriction happens
TPI limits power above 4500 ish on a 350 so would be even lower on a 383.
Get a better , higher breathing intake before you change the rear ( esp as Hib states with a T700 and that super 1st gear )

Some interesting reading for you.
http://xtremecarzone.com.au/index.php?showtopic=386
Look what a intake change does for a injected 383

just want a little more off the line .

Be careful what you wish for
I have 3.73's behind my 383 but with a single plane, 4bbl,TB intake it revs past 7K so it has much longer legs in each gear.
Notwithstanding , WOT on street tires there is no traction until D
Even my strip MT ET Streets will break loose on the 1-2 shift on the street @ WOT