3.73 worked real well in my 98 M6. With 4.10 you can forget about coming out of the hole in 1st with radials and expect any kind of hook. JMO

 

as dan told u before man just get some 4.10s and be doen with it or some get those the will work good with a 28' tall tire

 

I've seen that link before, and I believe that its off a little. Either way I know that I was way into the limiter (6600rpm's) with stock tire height, bouncing off it trapping 119.69, which is almost exactly 1 more mph then you have listed on your web page (118.70 not 119.00).
What was your tire height when you ran? And what RPM were you at when you crossed the traps?


Peace,
Craig.

 

i crossed the traps at 124 pegging 4th at 6700RPMS w/ 26x10.5x16 ET Streets, i lost the time slip otherwise i'd post it.

I never made it to the track once i had the 15in Prostars though.

 

Jeremy doen't ever take his car to the track, and the only tracks around this area that are open are 1/8 mile tracks at that.. So I beleave that the 4.10's would work great.. And if he did want to go to a 1/4 mile track, I would just put on a set of 28's and be done with it...

 

3.73's

 

I will go 3.90 when i go to the 9in rearend. As far as 390's whining, it's all in the install, plus don't use crappy gears. I should know, I built semi trannys, car trannies, and rearends for two years, no complaints from any customers. Gm rearends are a bitch anyway, you gotta have a lot of shims on hand ,and a surface grinder to fine tune the carrier shims- just takes patience.

 

Someone once told me that if you are using a grinder or dremel to fix parts.... something is wrong. I wonder how true this is??

maybe this is regarding sliders etc in the trans.... but whatever.

 

hey dude, before you postup, find out what a surface grinder is. it's operated like a mill, u do know what a mill is right? the parts are held down by an electric magnet, and instead of using endmills and such, it has a stone, so you can take off a couple thousandths at a time, evenly, from any flat surface. any good rearend shop has hundreds of old shims just for this purpose, sometimes you gotta fine tune the shims to get a good pattern, especially if the pinion depth is correct.

 

I can honestly say I have never seen a surface grinder used on shims on a rearend. Nor do I work in a shop. Thanks for the lesson and clarification. Shoulda searched google first... you are right.

what I was thinking of are grinding down the sliders by the syncro's in a T-56.... not shims in a rearend.

I'm not a moron.

 

just bein a smartass bout the moron comment. whats with grinding on the synchro's, never heard of that.

 

About the rear gear swap, here's a comparison for a stock 2002 M6.

My M6 has a 3.42 rear end and the stock T-56.

At 60 mph in 6th gear, I'm turning 1344 RPM. With a 3.73, I'd be turning 1465 rpm. With a 3.90, I'd be turning 1533 rpm. With a 4.10, I'd be turning 1611 rpm. Just a comparison.

Stock, these cars turn the quarter mile in the low 13s at a trap speed of 105 - 108 mph. Let's say you wanted to be able to run the quarter mile without shifting out of 3rd gear, and you wanted to turn about 110 mph while doing it. You'd need a 3.20 gear to do that.

With a 3.42, your speeds at 6000 rmp are: 1st: 50 mph, 2nd: 75 mph, 3rd: 103 mph, 4th: 134 mph.

With the 4.10, your speeds at 6000 rpm are: 1st: 42 mph, 2nd: 62 mph, 3rd: 86 mph, 4th: 112 mph.

So, if you go to a 4.10, you'll be in 4th at the end of the quarter mile, not 3rd. I'm not saying that is good or bad, just throwing out the numbers for you to consider.

Personally, I would not go to a 4.10 with the stock read end. It is weak to start with (so is the stock clutch) and a 4.10 means a gear with less metal in it, making it weaker. You can drive it fine, but it won't handle abuse at all. If I were getting a 4.10, I'd go with a Ford 9-inch rear end and an upgraded clutch.

About the highway, with my 3.42, I'm doing 1568 rpm in 6th gear at 70 mph. With a 4.10 at 70 mph, I'd be doing 1880 rpm, and that is still just above idle rpm, so a 4.10 would work fine for me.

Last, the 4th-gen Camaro is electronically limited to 161 mph by the computer unless you bypass it. With the 3.42 rear end, at 6000 rmp, 5th is good for 181 mph ... which means the engine limits before you get there. 6th would be good for 267 mph ... IF you could get to 6000 rpm in 6thm which you can't.

OK, let's limit the top speed in 6th gear to 170 mph. That would take a 5.39 rear gear. With the 5.39, you'd still only be turning 2470 rpm in 6th at a 70 mph crusing speed, and that is acceptable to me.

Just some food for thought ... not recommending anything.

Oh yeah, all the numbers above are for the stock tire size (275-40R/17). If you want numbers for another tire size, that's easy. Let me know.

For you techies out there: in the T-56 as sold in 2002, the internal gear ratios are: 1st: 2.66, 2nd: 1.78, 3rd: 1.30, 4th: 1.00, 5th: 0.74, 6th: 0.50, and reverse is 2.90. So, at 6000 rpm, any deranged 2002 F-Body owner can back up at 46 mph if so inclined. That would, of course, decrease to a lowly 38 mph if you went to a 4.10. , but you'd probably beat a Mustang doing it.

 

just read your right up... very nice.

sounds like 3.73's are the way to go if you want to stay in 3rd on the 1/4 mile!

 

QUOTE: 5.7 > 3.8SC > 3.4 > 3.8

Just curious as to what this means. Are the 3.4l's better than the 3.8l's?

 

Depends on what you mean by "better." As with any rear end change, there are trade offs.

You can go with anywhere from 3.10 to 5.39 and still have the rpm available to go 170 mph or more ... IF the top speed limiter is turned off and IF you make that much HP. Mine is about 30hp above stock, so I'm not in the "Hi-Performance" category yet.

Persoanlly, I like the 4.10 ... but NOT with the stock rear end and clutch (for my M6). If I were sticking with the stock rear end, I'd opt to stay with the 3.42. If I had my druthers, I'd go with anywhere from a 4.10 to 4.56 in a Ford 9-inch, a Mosler 12-bolt, or a quick-change IRS unit (saw one in Kitcars) instead of the solid rear axle. If I were road racing, I'd go with the IRS unit.

To me, Zexel-Torsen doesn't mean anything except a solid axle. Independent Rear Suspension (IRS) rules.

I'm just offering some comparison number ... not making recommendations. The recommendations depend on what you want to do with YOUR car. Want to beat a Z06? Then you can't stay with the stock engine and rear end.

The best in my book is to change the internal ratios of the T-56, but that takes a real pro and some bucks or a a real pro at home with some gaskets and spacers. I'd change the ratios so 5th is 0.85 and 6th is 0.70, and then go to a 3.71 rear axle if using stock tires or a 3.91 if using tires that are slightly bigger in circumference than stock ... but that's just me.

I can easily do the calculations and will send YOU the Excel file to do the same if you want. The formulas are simple, and you can "what if" to your heart's content.

If there is a way to post this spreadsheet on this forum, someone PM me or let me know in this thread, and I'll be happy to post it with instructions. There formulas are basic physics and some are straight out of "Hot Rod" and "Road and Track." Those would be the quarter mile estimates based on weight and HP.

 

I have a TA.... I have a GTP.... I had a Grand Am GT w/ 3.4 LA1 60 degree v6 and it was much faster than Grand Prix GT's......


so ......................

5.7 > 3.8SC > 3.4 > 3.8