HioSSilver

iTrader: (8)

I run a 275 15 nitto that's 26" tall

dbs1

Besides the 28" tire looking a little goofy imo, with the 3.73 gears it would put the effective ratio back down to 3.46. With 3.90's using 28 inch tires it would be like a 3.64 gear.

Of the 3 tracks I run on currently for road racing, the longest of the three uses the 1/4 mile drag track as the straightaway, so you get a big sweeper coming out of the staging lanes, then at least another 200 ft (depending on when you decide to start braking) for the straights. If I push it with the 3.42's I'll get to 125mph. With the 3.73's I'm guessing perhaps another 1-2 mph is possible running the rpm's up to where my shift light comes on, but not enough for valve float.

With the 3.90's it might put me at 6600 which is close to the point I'd be having that issue, but I would go backwards at that point having to shift into 5th, just to almost immediately downshift back into 4th.

Having a little more umph out of the corners with the 3.73 gears and possibly a 25 shot of nitrous may be the ticket. If it was a track only car I think hands down the 3.90's would work better and again, then use the 28" tires if need be. Another thing for me to consider is the downshifting to slow down and the 3.73's might be a better option in a hard downshift to make sure the rear does not get squirrely on a greasy track.

Since I bought a used set of 3.73's from a guy here on the site I guess we will be finding out how well they work. The other 2 tracks are shorter and I am sure the 3.90's would be an advantage there. Getting a 100mph in those straights is an accomplishment for my car.

BlkBird2000

iTrader: (10)

I've have 4:10s in my 10 bolt. It was a blast to drive. Short gears. Top of 4th was about 115. I went to 4:56 with a spooled 9" and it was fun too just not very fun to drive on the street. I am now back down to 3.75s with a wavetrac. I haven't gotten on it but it really doesn't feel much different from your normal daily driving. RPMs are are different by just a few hundred. Good thing, I think, about 3:73s is you can use it for every aspiration. NA, FI, and nitrous and it will work well with each. I should never have to change gears again since I don't ever plan on using a turbo. Procharger is where i'll be heading.

A2Garcia3

I have recently bought a 99 pontiac trans am ls1 5.7l (6 speed manual transmission) im starting to step my feet into getting it ready for what ever occasion (track or street)! On the motor i have longtube,x-pipe, custom tune, my uncle mentioned having gears but doesn't remember!..! Past Saturday I installed 26's MT ET STREET & 1st pass beat a Z06, 2nd pass i beat a 5.0 and then after that race started hearing noises from the rear end! Please help! (Yes it has TCS)

mackdaddy66

I have 3.73 gears and still have a problem off the line with wheel spin on the street even when not using the sauce... was real bad when running drag radials, a lot of it has to do with how much power you are making... don't want to run out of rpm way before the finish line... am running 28x13.5x15 et streets now, they hold the best for my stick car so far but sure would suck for road course I am sure

A2Garcia3

With these 26x11.50x16 i didn't have problem i just want gears that won't blow if i launch like 2800-3400 rpms!

mackdaddy66

I launch at around 4700 and shift at 7k... if I launch at 3500 I am way out of my powerband... at the strip car hooks good but I am thinking of getting an anti roll bar

A2Garcia3

Wow that good but i launched on 4k and thats when it started making its noise (like a thrown out carrier bearing on a pick up) and in that case i probably just had stock gears then huh!? Also when i jacked it up on jack stands it as soon i slowly let it spin a lil it started locking and my TCS light came on too any idea?

mackdaddy66

my car didn't have traction control, but from cars and trucks that I have seen that had it, the system would apply the brake on the side that was spinning diverting power to the wheel that had traction so I would assume on a car with traction control it would have an open differential. so the first thing I would be checking is to make sure there is not a brake caliper sticking or possibly that for some reason the park brake is not releasing all of the way thus causing noise due to glazing from the heat. it may not be the cause of your noise, but it is easy and free to check those things. if nothing found wrong there make sure the diff is full to the bottom of the fill plug opening and check to see what the gear oil looks like... should not have anything looking like glitter in it, while under the car checking that check pinion axial endplay and rotate pinion back and forth to get an idea of how much backlash there is in the diff and spin it a few times to see if you can hear where the noise is coming from... maybe can hear it at that low of rpm and no load, maybe not, but worth checking... could be a backing plate or something bent and hitting a rotor... be conservative and check the cheapest things first... I would also be saving up money for a good differential for when your stock one bites the dust... keep an eye on the classifieds here on ls1tech and sooner or later you will find a good deal

mackdaddy66

your traction control light may be coming on while you are letting the wheels rotate while on jack stands because one wheel is moving faster than the other and it is doing it's thing that it is supposed to do.. a friend of mine has a mustang with it and when he drag races he shuts it off, but I do know from my girlfriends car that has it, that it is effective for helping with wheel spin to a point.. once you get to a certain point as far as power you are better off to run a good posi unit in a real good strong diff or do what ever you can as far as stud girdles and such to beef up a stock 10 bolt

mackdaddy66

posi units or even complete differentials for the f bodys are pretty cheap and plentiful and a lot of them have posi.. mine did and so did a friend of mine .. they are just weak and that is why a lot of people get rid of them before failure and they are worth a little bit of money

A2Garcia3

I see! Hmmm? As for now til i save for a good rear end what would be recommended for what's on the car! As in a stock rear end

mackdaddy66

if yours checks out good run yours and get a rear cover set up for a stud girdle to help give it some support and prolong it's life for a while... as far as an aftermarket diff you need to decide what the end game is of your car... no reason to blow a bunch of money on a diff that way surpasses what you plan to do... if making a lot of horse and running a stick and nitrous you will need a real good one but if you are going to stay in the 400 to 500 hp range you don't have to buy a high dollar one.... if going to play around with gearing some get a 9" that is built to fit your car... easy to change carrier and gears and complete carriers are easy to find... I am running a strange s60 which seems to be holding up real well, but the internals are heavy so it takes some hp to drive it, but it seems to do real well in my stick car... my brother has a 9 inch in his car but he seems to go through at least one ring and pinion a year and he is putting less hp to the wheels than I am... but the 9 inch is lighter so he is happy with that.... if I was to do it over again I would probably do the 9 inch due to being lighter... I have over 700 hp at the tire now, but I wouldn't mind the lighter internals to get a few more hp at the wheels... now days a person normally has some dyno numbers, knows how much their car weighs and what size tire they are going to run and they can get pretty close on calculating what ratio they want to have.... on a lower hp car I would probably run 4.10 if it was just a weekend toy, if cruising around a bit I would go with 3.73

A2Garcia3

Thanks bud and its only a weekend car but i do sometimes go to my hometown in it which is an hour drive

mackdaddy66

with a n/a motor and 26 inch tires I think that 3.73 would treat you good... start spraying nitrous just step up to a 28 inch tire... it all has to do with what rpm you want it to cross the finish line and if you are willing to give up a little bit of fuel mileage. winter is coming and car parts usually get cheaper after racing season is over

A2Garcia3

Thanks ill look into them whats a good recommended brand names? Don't wanna buy any junk brand!

mackdaddy66

I would watch the classifieds here... strange, currie, a lot of different manufacurers out there, do a search and you might find one close to where you are from and save a bunch on shipping... just make sure it is specific to your car and you aren't trying to make one fabbed up for a mustang fit your car per example...or one that is narrowed more than what will fit your car without mini tubbing or back halfing so if you want stock width make sure what you are buying is for that application. I am partial to strange, but that I because they have been around longer than I have been breathing air so the name was always being displayed... some people say they are over priced, but most of the time high quality is high priced... if it is cheap it was probably made in china or japan... quick time is what my brother bought for his and he has had good luck with it too