XXO/BVGC '38 Chevy Coupe Build

[38flattie]

I've been offered a 3 speed, with GV overdrive, good for a 1000Hp. I'm thinking this would be the way to go.

[Kiwi Paul]

Buddy, Don`t forget to choose a combination that you can adjust on. if a quickchange and a bunch of spur gears aren`t on the menu, stick to your 9inch and round up a few gearsets to take. As for the 3 Speed and Gear Vendors idea, well, I hope Dale can learn the shifting system. I still like the idea of a Tremec and a batch of ratios in the back....

[Freud]

Buddy I wish the Target550 group could have provided you more help. Without coming to

your pits Marlo didn't have much to go on. We were up to our scrotum in alligators about

the time you came by.

I failed to get over the remaining days but I love your Caddy.

I'll lurk and listen for your next step.  You did great for a new outfit.

FREUD

[RichFox]

Buddy, Don`t forget to choose a combination that you can adjust on. if a quickchange and a bunch of spur gears aren`t on the menu, stick to your 9inch and round up a few gearsets to take. As for the 3 Speed and Gear Vendors idea, well, I hope Dale can learn the shifting system. I still like the idea of a Tremec and a batch of ratios in the back....

I believe it shifts like any other three speed which is the same as my truck around town where I don't use granny low or overdrive 5th. And then you flip a switch for Odrive. Millions built and people learned to use them. Why do you think Dale will have a problem?

[Tman]

I think that was a joke Rich.

[SPARKY]

I have run a AT 400/GV and no torque converter and I have run a PG/GV with no converter---
In a low HP high AERO DRAG combo  if you want to be combetitive you must minimise your total drag---you have worked hard on the body AERO

An area you have left is drivetrain effieiency--at Bonneville ---IMO  the cheapest-MOST power to the ground comes from not using 9" -4.5% fords
 and QC -6.5%  gear change with tires ---but especially trannys you can change the gear sets easily!!! like Libertys and such you can rally "Tune for the Eng/trap speeds you want

PS: If I could get my buddies with the red truck on board--(missed a hat by .5 MPH) they run a QC with a 2.74--real clsoe to a GM 2.73 which would put over 6% or in their case 65 HP more TE to the salt---think that might cover .5 mph

[38flattie]

Thanks everyone!

Kiwi Paul, I have a Halibrand Camp QC in the car, not a 9 inch, so changing gears is easy. I thought we had a gearing problem, but after running the numbers again, I realize we had to have had clutch slippage.

Sparky, I have a Liberty tranny, and will be talking to them Monday about gear selection, to decide if I want to stay with it. I think a rear end with about 2.35 gears will get us to where we want to be.

Suggestions?

[SPARKY]

with GMs you can do 2.41 or 2.28s  I would go with the 2.28s and continue to play with the liberty---let me have your dyno sheets and I will build you a TE chart that will show you what speed and what you are putting to the ground at each rpm on the dyno sheet!  You then will be able to play with gear selection!

[38flattie]

Thanks Sparky-I sent you the info.

Did anyone happen to get a pic of the FlatCad with the chute open? I really wanted one, but we missed it!

[panic]

Your HP curve will determine how much ratio spread you can tolerate on the shift into high gear.
Very peaky? 10-15% drop
Flat as Kansas? 25% drop

[RichFox]

The thing about the Liberty or the transmission in my Dodge is that when they are in fifth or sixth gear they are running through the cluster. And that has more drag than direct 3rd or 4th. The Ford top loader with the gear vendors OD runs through a planetary gear set for the Over drive. The transmission itself is in high and is running direct. So the question becomes which has the least drag and power loss? I don't know. I think it's the planetary gears. But I have nothing solid to back that up. Who has some real numbers they are willing to share? We could call Gear Vendors, but I think I know what they will say.

[Pete1]

The thing about the Liberty or the transmission in my Dodge is that when they are in fifth or sixth gear they are running through the cluster. And that has more drag than direct 3rd or 4th. The Ford top loader with the gear vendors OD runs through a planetary gear set for the Over drive. The transmission itself is in high and is running direct. So the question becomes which has the least drag and power loss? I don't know. I think it's the planetary gears. But I have nothing solid to back that up. Who has some real numbers they are willing to share? We could call Gear Vendors, but I think I know what they will say.

You lose 5 to 8% every time you go through a gear set..Slightly less if they are not driving.
In a planetary transmission like a Lenco, when you are in direct, no gears are moving. It is like a straight shaft going through with parasitic drag coming only from oil friction and loss in the bearings.
In a Bonneville car it is more efficient to NOT use an overdrive. The cheapest way to go would be have a push car that could push the race car
up to 100 mph.(Like the Kenz & Leslie 777) The race car could get along with only a clutch and no transmission then. The most expensive way to go is probably a Lenco.
Oh, I forgot, there is another way, have way more hp than you can possibily get to the ground and then you can afford to lose some in the drive train.

[RichFox]

I understand that. However my question has to do with an overdrive transmission. In direct i am aware the Gear venders unit is about the same as the Ford trans would be without it. But buddy want's an overdrive of some sort, between the flywheel and the rear end. So we are pretty much limited to a standard transmission in which top gear is an overdrive or an add on overdrive such as the Gear Vendors unit. The question is which is more efficient.   

[SPARKY]

the freewheel feature is nice---saves tires and shorts if you blow and eng. saves auto trannies when you push off the line.

[Jack Gifford]

... I have a Halibrand Camp QC in the car...

Umm... then why are you looking for a different ring/pinion set? What am I missing here?