gear help please

[Guest BigRay]

I have a 77 280Z that has a 383 stroker, that i use for racing only. The motor came out of a 77 chevy monza that ran 12's with the same motor my Z is in the 15's. I heard that I should be running 4:11's in the rear. is there a gear set availbe for purchace or do i have to do a rear end swap? Any help would be appreciated.

 

Thanks

BigRay

[Here comes trouble]

the 1985-86 200 SX turbo had a 4.11........81-83 non turbo zx's had a 3.90. ..1987--89 Turbo ZX's had a 3.90 LSD..... A search will net you a considerable amount of knowledge on differential swapping

[dr_hunt]

Hey Ray, what color is your car and when did you take it to the track? I saw a white hybridz getting towed out of there two weeks ago, just didn't know the history on it.

[Michael]

Ideal rear-end gearing would depend on a multidude of factors, including rear tire diameter, transmission gears, and operating rpm range of the engine. I recall mention of cars on this site running in the 11's or better, with tall gears such as 3.08; most Z's run 3.54, which is the most common ratio in R200 rear ends in 280Z's, and R180 rear ends in 240Z's.

 

But intuitively, it's very hard to ascribe a slowing down from 12 seconds to 15 seconds in the 1/4 mile to bad gearing alone, considering that the Z's weight is comparable to (if not less than) the Monza, the aerodynamics are comparable, and the Z has better weight distribution. Could it be that something went wrong with the engine, during the swap?

[awd92gsx]

What's your trap speed?

[Guest BigRay]

i havnt taken it to the track since last year. i was dissapointed with the time. but it is red.

 

BigRay

[Guest BigRay]

compression is at 160 in all 8 cylinders. took the motor back out and put it in a el camino and the el camino ran in the 12's also. i know it my gears, i have a decent top end just no out of the hole, or bottom end.

 

thanks

BigRay

[Guest BigRay]

trap speed is 86 mph.

 

thanks

BigRay

[Scottie-GNZ]

trap speed is 86 mph.

 

thanks

BigRay

In the 1/4-mile? That is what it should run at the 1/8-mile or even faster. Post a side-by-side comparison of the 12-sec pass in the Monza and the 15-sec pass in the Z.

[dr_hunt]

An el camino is heavy, like 3500 lbs, the z is alot lighter. I'd expect higher trap speed than that in the 1/8th when in the z. Sounds kind of like there is some other problem.

[awd92gsx]

Even if you had some custom one off 2.x:1 ratio rear end, a 383 in a Z should be running faster than 86mph in the 1/4 mile.

 

There's something else wrong with your car. The rear end is fine...ESPECIALLY for a 383.

 

It'd be one thing if you had a 4,000 pound car with a 305...but, we're talking a sub 3,000 pound car with a 383 cubic inch V8. Your '77 280Z should have a 3.54 rear end, which is already a bit shorter than most Chevy's. (hence the reason TH350's work like garbage in a V8Z on the freeway, even though in the Chevy chassis with Chevy rear end it works perfectly fine).

[Guest zfan]

This makes no sense. The gears in the Z car are all good, its not like you are going to find 2.56's in them. They go from 3.36 up to 410 I think. Sounds like you have some serious tranny or internal rear end problems.

 

My Z will run 11's on any gear they offer in a r200.

 

Mike

[Guest BigRay]

so where can i find other gear set for it so i can try something else.

 

 

Thanks

Ray

[Guest BigRay]

i guess that the other thing that i should have mentioned and sorry for the mix up is that, the monza runs a 4:11 gear ratio and the el camino ran a 4:56 ratio so i do have a feeling i have alot less gear than i should for this type of motor. any old chevy i have tried this motor in so far has ran in the 12's but has run 4:11 or 4:56 gearing.

 

Thanks

Ray

[Guest BigRay]

what type motor do you run in your Z? is it highly modified, light mod, mild, or stock

 

Thanks Ray

[awd92gsx]

so where can i find other gear set for it so i can try something else.

 

 

Thanks

Ray

 

Ray' date='

 

You're hearin' us, but, you ain't listenin' brutha!!

 

People usually run much faster than you on engines WAY smaller than a 383 using standard Datsun rear ends without any custom, or non-stock, rear end gear ratios.

 

The 383 is a stroker motor designed to give power in the low to mid range RPM power band. Unless you've dropped an extra 2,000 pounds in your Z that would require MORE torque than what you're getting out of the engine there is absolutly, positively, indubitably, nothing wrong with the gearing of a Z...or AT LEAST not enough to make such a big difference in what you *should* be running vs. what you are running.

 

Your Z doesn't NEED any more torque than what a 383 can put out to run a solid 12 second or faster time [i']through the stock Datsun 3.54[/i] rear end.

 

Either A) The engine is not running correctly on all 8 cylinders or The power transfer from the engine is being lost between the engine and the ground through slippage somewhere.

 

i guess that the other thing that i should have mentioned and sorry for the mix up is that, the monza runs a 4:11 gear ratio and the el camino ran a 4:56 ratio so i do have a feeling i have alot less gear than i should for this type of motor. any old chevy i have tried this motor in so far has ran in the 12's but has run 4:11 or 4:56 gearing.

 

Don't forget that the El Camino probably had a curb weight of around 3500 lbs and the Monza around 3200 lbs. Even IF your Z weighed as much as the Monza, the gearing isn't going to change your ET 3 seconds and it would probably have less of an effect on your trap speed.

[Guest BigRay]

so where should i start. i would like to correct this problem so that i can go on to other things. im just now sure why the other two cars are so much faster with the same motor and alot heavier.

 

Thanks

Ray

[awd92gsx]

Can you post your timeslip?

[Scottie-GNZ]

The problem has nothing to do with gearing so put that out of your mind. Post the Elky and Z timeslips side-by-side so we can see the comparison and try to help.

[dr_hunt]

Ray, Need your tire size and rpm limit as well. I run a 29.5 inch tall rear tire, and am switching to 4.11 gears with a 406. It had 4.56's in it before but was bumping the 7K msd chip about 200 feet before the end of the track and top trap speed was 126 and change, and if you punch that info in to a tire/gear/speed program with converter slip, you get about 7000 rpm. I want to bring mine down to about 6500 here and make room for the 20% HP gain when and if I go to SEZ6. Point is, use one of those programs that is on the net, it'll give you a feel for what you have and where you want to go with the powerband, rpm limit of your engine. I'd expect some low 11's from your setup in the z. My guess is depending on your tire combo 3.90's to 4.11's should work.