DragStuff

I currently have 4.86 progears in my car. I have to drop them because the RPMs are shooting up way too fast in the car. I cant stay in the gears at all. I have a 400 turbo trans. I was thinking about dropping it down at a 4.29 progears.

What you guys think?

Blade wrote:I currently have 4.86 progears in my car. I have to drop them because the RPMs are shooting up way too fast in the car. I cant stay in the gears at all. I have a 400 turbo trans. I was thinking about dropping it down at a 4.29 progears.

What you guys think?

Not sure what you mean by the rpms are shooting up too fast.

I always gear the car to hit the target finish line rpm.

I figured I am in high gear just pass the 60ft marker. If I drop the gear ratio in the ring and pinion, I should be able to stay in the gear longer?

Maybe a little, but why are you worried about that?

What diameter tire?

I ran a th400 (stock 2.48 1st), 4.11 pro gear and a 28" tire. Never had much problem hitting the shift points. I was usually shifting into second gear around the time the front tires touched the ground from the wheel stand, 3rd gear was further out.

Ever checked your converter slippage?

What's your tire diameter, mph and finish line rpm?

Is your finish line rpm correct for the combination (just past peak HP)?

DOTracer wrote:Maybe a little, but why are you worried about that?

What diameter tire?

I ran a th400 (stock 2.48 1st), 4.11 pro gear and a 28" tire. Never had much problem hitting the shift points. I was usually shifting into second gear around the time the front tires touched the ground from the wheel stand, 3rd gear was further out.

Ever checked your converter slippage?

What's your tire diameter, mph and finish line rpm?

Is your finish line rpm correct for the combination (just past peak HP)?

A buddy of mine said that I was losing et and mph from the gears being too big.

The slicks are 14*32*15

I am corssing the line at 6300

I was thinking about dropping down to 4:30s

Blade wrote:

DOTracer wrote:Maybe a little, but why are you worried about that?

What diameter tire?

I ran a th400 (stock 2.48 1st), 4.11 pro gear and a 28" tire. Never had much problem hitting the shift points. I was usually shifting into second gear around the time the front tires touched the ground from the wheel stand, 3rd gear was further out.

Ever checked your converter slippage?

What's your tire diameter, mph and finish line rpm?

Is your finish line rpm correct for the combination (just past peak HP)?

A buddy of mine said that I was losing et and mph from the gears being too big.

The slicks are 14*32*15

I am corssing the line at 6300

I was thinking about dropping down to 4:30s

I know nothing of your engine combination, but 6300 does not sound very high at all.

I shift my 582 bbc at 8000 rpm and go through the traps at 8200 rpm (peak hp on the engine dyno was 7500). 1.80 glide, 6500 flash converter, 4.11 gear 30" tall radial tire.

That is what I was thinking. I should be higher

Got a new 400 trans with a brake in it, new externally balanced flywheel, and changing the ring and pinion.

What ones?

http://www.jegs.com/i/JEGS-Performance- ... tId=750807

http://www.jegs.com/i/Richmond-Gear/836 ... tId=744484

imo,...you are not going to be happy with that gear. Like some one else in here has said in a lil' nicer way,.... you're basically idling across the line. You're running 14x32 tires??? I just think you are going to regret spending this money.

What does the lower end of your engine consist of again,...upper end too while you're at it. Throw the cam specs in as well.

It was also mentioned in this thread somewhere that your converter could very well be the issue. If you're in 3rd gear by the time you're getting past the 60ft lights you're slipping something radically imo. Tires, trany internals, or converter. Is the front end coming off the ground at all? This a ladder bar, 4 link, or stock suspension car?

If these are for a 9" rear make sure you get the shim pack instead of the crush collar.

All this is just an opinion of a want-a-be, so you may want to take my advice with a grain of salt.

Don

want-a-be wrote:imo,...you are not going to be happy with that gear. Like some one else in here has said in a lil' nicer way,.... you're basically idling across the line. You're running 14x32 tires??? I just think you are going to regret spending this money.

What does the lower end of your engine consist of again,...upper end too while you're at it. Throw the cam specs in as well.

It was also mentioned in this thread somewhere that your converter could very well be the issue. If you're in 3rd gear by the time you're getting past the 60ft lights you're slipping something radically imo. Tires, trany internals, or converter. Is the front end coming off the ground at all? This a ladder bar, 4 link, or stock suspension car?

If these are for a 9" rear make sure you get the shim pack instead of the crush collar.

All this is just an opinion of a want-a-be, so you may want to take my advice with a grain of salt.

Don

YES the slicks are 14x32

Doesnt have larger tires drop the ratio in the rear gear. So if you have 4.87 then its equal to having 4.56?

So far as the motor wont know exactly inside until we break it down and refreshen it.

But I keep hearing that I am losing et and mph with those larger gears in the rear and that 4.87 is used for 1/8th. My 1/8th mile time is 7.01 and my 1/4 is 11.20s at 124mph.

The car is a ladder bars, the trans that I was using before breaking the housing didnt have the break in it. The Convertor is an ATI 8inch 4500. The rear is a 9inch with strange center section with moser axles.

Hmmm,...well,...after thinking about this a bit more. You are running a 3 spd tranny as opposed to the glide. I'm not used to that myself as no one I know or have help uses a 3 spd tranny. Launch gear will be lower I guess.

You are crossing the stripe at 6300 in the 1/8th or the 1/4? How much 1/4 do you run and how much 1/8th?

When I was racing a vega years ago I was running the 14x32s with a 5.67 gear. Would cross the stripe at about 7200. But I never ran 1/4. Wasn't afraid of running that thing to 8500 anyway so it didn't matter. It had a glide in it though. I always wanted to try a 5.80s or a 6.0 gear in that car but never got around to it. it ran 5.80s and in the low 120s or so... Just a little nothing cast iron headed 355. ladder car also.

Don

want-a-be wrote:Hmmm,...well,...after thinking about this a bit more. You are running a 3 spd tranny as opposed to the glide. I'm not used to that myself as no one I know or have help uses a 3 spd tranny. Launch gear will be lower I guess.

You are crossing the stripe at 6300 in the 1/8th or the 1/4? How much 1/4 do you run and how much 1/8th?

When I was racing a vega years ago I was running the 14x32s with a 5.67 gear. Would cross the stripe at about 7200. But I never ran 1/4. Wasn't afraid of running that thing to 8500 anyway so it didn't matter. It had a glide in it though. I always wanted to try a 5.80s or a 6.0 gear in that car but never got around to it. it ran 5.80s and in the low 120s or so... Just a little nothing cast iron headed 355. ladder car also.

Don

I was crossing the stripe at 6300 in the 1/4. I am running the car at 1/4 mile tracks. The 1/8 mile time was off the slip.

After doing some thinking, this time was off a motor and flywheel that was NOT properly balanced. So the time should change.

what are your shift points.

Don

I was planning on shifting at 6500 but with the RPM going up so fast pretty sure I shifted early.

When I shift frm first to second the RPMs didnt drop. So I was going right to Thirds.

Sounds like you need to find out what is in the lower end of your engine. If it would hold up to the rpm,...I'd stretch it out to at least 7k or so. I sti;; think you'll end up putting your old gears back in the long run.

Need to revisit this question after you find out what is in the engine,...Carb to pan.

Don