Which overdrive transmission and rear gear?

[MaineShark]

I'm currently thinking about putting in an overdrive transmission, and debating between the 700-R4 and the 200-4R.

The 700-R4 would work very well with my stock rear-end ratio, which is a good thing, because it requires a new crossmember and modifications to the drive shaft to fit, which costs a decent amount of money.

The 200-4R would not work well with my stock ratio, but it bolts in with little expense, meaning I'd have enough left over to buy new rear gears. That would give me a new transmission, and new rear gears. So, I'll probably go this way.

To look at the ratios:

With my current rear gearing (3.55:1), the overall ratios for the 700-R4 are 10.86:1 in first, 5.75:1 in second, 3.55:1 in third, and 2.49:1 in fourth.

With 3.90:1 rear gearing, the overall ratios with the 200-4R are 10.69:1 in first, 6.12:1 in second, 3.9:1 in third, and 2.61:1 in fourth.

So, the 200-4R will not give me quite as good of a first gear (high number is better) or as good of a fourth gear (low number is better), but the first gear will be within 2%, and the fourth gear difference will only amount to 100 rpms at 70mph. The 200-4R will have more aggressive second and third gears, though, which should help with in-town driving.

Alternately, I could go with 3.73:1 rear gears with the 200-4R, and get 10.22:1, 5.86:1, 3.73:1, and 2.50:1. So, I would have essentially the same gear in fourth, but first gear would not be as good (over 6% difference between this setup and the 700-R4), although second and third would still be more agressive than the 700-R4.

So, my real debate is which 200-4R setup to go with, not between the 700-R4 and the 200-4R.

Thoughts?

Joe

 

[page62]

How many HP are you producing? This will determine what flavor of 200-4R you're going to need.

Are you interested in 1/4-mile times? If not, the 200-4R/3.55 combo is going to be just fine.

Bottom line: In either case, just drop in a 200-4r and worry about the rear gear later! Fortunately they don't all have to be done at once.

 

[Tom73]

I agree, drop in the 200-4R and then drive it awhile. It may be just fine as is or you may need to do some fine tuning with the rear gear to get just want you want. No need to do it all at one time.

tom...

 

[MaineShark]

I think doing it in two stages is a great idea. While the first and second gear ratios are not dramatically different, the 200-4R would definitely be an upgrade from the TH350, and the overdrive is the big goal. The rear gear can be changed later, bumping the performance up quite a bit.

Page62: Right now, I'm putting 200hp to the rear wheels (so, probably 225-250 at the crank, depending on whose correction numbers you use). But, I plan on building a 400-hp 406, which is the big reason for the upgraded transmission. My stock unit already has 100k miles on it, and wasn't taken very good care of by the previous owner, so I don't want to put that kind of power to it. I, of course, could replace it directly, but if I'm going to yank the transmission anyway, I want overdrive... gas is getting pricey.

I talked to Bowtie Overdrives, and they recommended their stage two 200-4R for this power level.

I don't really plan on racing at the drag strip, often, but I probably will occasionally go on their open nights, just for fun. And I really love that pinned-to-the-seat accelleration, even in ordinary driving. It's practical, too - being able to accelerate quickly can get you out of dangerous situations, and good 0-60 times directly translate to merging onto the highway.

Plus, there are far too many ricers out there that, due simply to the modernity of their cars, and not due to any of their own skill, can out-perform a C3. I enjoy putting them in their place, and want to increase the diversity of sticker-charged commuter cars which I can stomp

Joe

 

[page62]

I don't know how much you've done to your L82. But mine has true duals, an Edelbrock QJet, and a Lars-recurved distributor. It's pretty quick!

In fact the other day, as I was getting on the freeway accelerating in 3rd, I pressed the throttle down for more speed. The car downshifted into 2nd -- WHAM! -- and pressed my kidneys into the seat. Afterward, my wife asked "What the heck was that?" That's a good sign I've achieved sufficient performance...

I've given up trying to keep up with modern vehicles. It's time we all started realizing these cars are classics, and could basically whup all other mass-produced cars of their era.

 

[MaineShark]

Well, mine isn't really an L82. The car originally was, but the engine has been replaced, at some point. The only mod I've done is true duals, and a recent (Tuesday) trip to the dyno showed 200 hp (4200rpm) and 260 ft-lbs (4100 rpm) at the rear wheels.

Don't get me wrong, it moves pretty dang well when I stick my foot in the carb, but I want more Nothing too extreme - basically just getting back the performance that I feel the Sharks should have had, if it weren't for the silly smog laws.

To me, that's "restoration"

Joe

 

[MaineShark]

Thought I'd bring this back up...

A few thoughts to ponder, since the cost of swapping the rear gears is a bit more than I originally thought:

200-4R: $1800, plus cost of labor to swap rear gears.

700-R4: $1800, plus cost of shortening driveshaft.

So, the 700-R4 is going to be a bit cheaper. From what I gather, shortening the driveshaft should not cost more than $150-200, while swapping the rear gears will start at $200, and probably be more.

On the other hand, the 200-4R swap would mean fresh rear gears, and a chance to make sure the diff is in good shape (of course, that could mean greater expense). The 200-4R also offers full-throttle upshifts.

And, as a couple people mentioned, the rear gear can be swapped at a later time since the 200-4R, even with my current gearing, is a significant upgrade from the TH-350. First would go from 8.95 to 9.73, second would go from 5.40 to 5.57, third would be the same, and fourth would drop my highway by a third.

200-4R, without rear gear swap: $1650

That does look more appealing (doing it in stages), and will ultimately offer a better second and third gear than the 700-R4, but never the quite same first gear.

Still, I want to get as many opinions as possible, before making any sort of final decision. Particularly any opinions from people who've done the 200-4R swap - the 700-4R seems to be the most common, which leads me to wonder why since the 200-4R seems better, at least on paper.

Joe

 

[page62]

You're worrying about those rear gears WAAAAY too much. Quite frankly, I doubt you will feel compelled to change the gears after you've done the tranny swap.

Bear in mind that what you're considering is exactly the setup I have (BTO Level 2 200-4R, 3.55 gears) so I should know what I'm talking about. As it is, I barely spend any time in 1st gear. If I had a 700R4, I'd have to be really careful every time I pulled away from a stop!!!

The 200-4R is cheaper than the 700-R4 because you can use the stock crossmember (which saves about $179). And there is no driveshaft cutting.

If properly built, either tranny is a good choice. Here's the criteria that Bowtie uses: If your rear gears are 3.08 and lower, go with the 700-R4. If the gears are 3.55 or higher, choose the 200-4R.

Just do it!

 

[MaineShark]

Hmmm... first time I talked to Bowtie, they said I should use a 700-R4, because of my rear gearing. But I see where you're coming from, and I think you're right that having too much first gear could get tiring. I still think I may do the rear gear swap, but at a later time. If for no other reason, than the original has over 100k miles on it, and I'm looking at some engine upgrades that will put quite a bit more torque on it. I'll have to pull the diff anyway, to check it out, so I might as well do that while I have it apart

Just do it!

I think you're right Let's see, my Shark was built in August of '78, so it will turn 25 this August. Sounds like a good birthday present

Joe

 

[patsnitrovette]

Maine shark i just recently got my 700r4 swap finished and i have 3.70 gears and 1st gear is very short,winds out very quick .But i wouldnt change them for the world.

 

[page62]

It all depends on your goals. If you want a seriously quick launch, like Pat, go for the 700R4. If your car is a driver, like mine, then the 200-4R is an obvious choice. Neither is better; it's what you want out of it that makes all the difference!

 

[wichitacorvette]

i bought my 700r4 performance tranny w/with stage 3 b&m shift kit and bands and bilet servo for 700 from ebay....... New. the guy had sold a couple online but i cant find his user id....... there are many companies online that sell 700's just do a search on ebay........ it will at the least give you some ideas...... 700r4 all the way...... my rear end is 2.87 stock gears......a nd she kills EVERYTHIGN off the line and 60ft, but a little above the 1/8th it gets close....... and by the quarter its over...... im thinking of a higher gear maybe 3.11 or so...... can that be done in the 82 rear end?