InfernalVortex

iTrader: (4)

Before christmas I took the 3.27's out of my 9-bolt and put in some 3.70's, and by I, I mean I paid for the gears and had mw66nova do it while I took notes so I could do it myself next time. Just wanted to note a few things for all the 9-bolt guys who end up doing searches about this sort of thing.

-Gear availability is pretty limited unless you want to order from Australia. I wanted 3.70's or 3.90's, ended up just getting aftermarket 3.70's.

-I got my 3.70s from biggearhead , very friendly, communicative, and good seller. I was a bit leery of buying from a guy with (at the time) 300 posts and a paypal account who was a "dealer", but he has a good reputation on other boards and I took the plunge. Got my gears within a few days in a new unopened package for around $200. I would definitely buy from him again, and would recommend him to anyone looking for gears. He carries Yukon gears.

-My 3.70's are Yukon brand. A few other brands make them in that ratio, some say (noisy) in parentheses or asterisks after the part description. Some don't. Not sure what to make of it.

-The backlash ended up at about .007, which is, according to who you ask, perfect for a 9 bolt, or a little tight. I've heard differing theories on whether loose vs tight is better, both make sense, so I dont know which to recommend to anyone.

-My old pinion gear was a bear to get out of the housing. Had to pull the axle and beat the hell out of it to get it to give up on life. So be ready to pull the axle off the car. mw66nova taught me a neat trick of using vice grips on the brake line to keep the brake fluid from leaking out, worked beautifully.

-After a few tries, the pattern was beautiful, and the backlash was at .007, so we decided to call it good. There is noise at 50mph+. It hasn't gotten worse, it hasn't gotten better. It just is. Might be a little irritating for the more refined street cruiser cars out there, but my exhaust is louder than the gears and with the radio on I dont notice it. Very tolerable to me and there's absolutely no noise at all around town. Patten was beautiful and backlash was within spec, preload felt good, so it's anyone's guess as to whether the setup is a little off or the gears are just inherently noisy.

-I got all my shims/gaskets/bolts/pinion spacers from http://ratech.stores.yahoo.net/79bogmax.html . They are fantastic for those kinds of parts, heavily recommend a solid pinion spacer. Their installation kit is excellent but includes a crush sleeve.

So in summary, biggearhead is a good seller, just bite the bullet and pull the axle off the car, the Yukon gears seem good but noisy at highway speeds, and ratechmfg is great for random parts.

But before you go through with it, consider going to a stronger rear end before dumping this kind of money into a 9-bolt, and DEFINITELY check the posi cones before you do all this. The reasons Im sticking with my 9-bolt is convenience (I already have it) and Im not making enough power that Im willing to give up power at the wheels. The 9-bolt doesnt suck near as much power as the 12-bolt and 9 inch do. If it lasts a year or two it'll be worth it, if it blows up this summer, then I will have a different opinion. Probably just recommend you to use a 10-bolt where you can find replacement parts everywhere cheaply and use a torsen posi.

And in case anyone is wondering, the gears were one of the best mods I've done to the car, period. They're up there with the T56 and the Koni yellows.

85FBTranam

iTrader: (3)

What did you do about the speedo recalibration?

InfernalVortex

iTrader: (4)

My T56 doesnt work with my factory speedo to begin with so it was of no consequence. However I am planning to get the SGI-5 box from Dakota Digital that converts the VSS signal from the trans. I think it's the 89+ cars that got the electrical speedo, so you'd have to play around with speedo gears and that's not anything I've got any experience with.

Keoman

iTrader: (3)

BACK FROM THE DEAD!!

Ill just add this in case anyone is looking in the future about 3.70's.

https://www.thirdgen.org/forums/tran...0s-really.html

I agree with InfernalVortex, they just make some noise. Just have to deal with it.

mw66nova

iTrader: (13)

so, the car has a year on it since we slapped those gears in it...how's the noise now kyle?

InfernalVortex

iTrader: (4)

Its the same as it ever was. Just past 50ish mph you start to hear it. It's noisy on coast and acceleration at those speeds so it's consistent. Around town speeds there's no noise. Hasnt gotten worse at all, and it hasnt gotten better. Made a huge difference in drivability and I can still barely use 6th gear...

Atilla the Fun

With an XE262 I'm not surprised. I'd definitely get the 3.90:1 gears.