mickman

I had the 373 gears in my car last year. They are ptp's made by richmond they say. Since day 1 they have whined terribly, my mechanic has also talked about difficulty in setting them up! when i went to buy gears the guy at the race shop he asked if my car was 7.5 or 7.625, i said I don't know, he said we needed to know. I called countless dealerships and came up with nothing, the race shop guy called a mechanic and he said its the same thing? so i got the 7.5 and this year they are srewed up. when we checked my original 2.73's and the ring IS bigger than the new one and appears to be a 7.625! PTP sells 2 versions of gears we just discovered, 1 for 3.08 and lower carriers and 1 for 3.23 and higher carriers. Here we thought the problem was solved right? wrong, the code on my 373 box says its for the 3.08 and lower carrier wich I have. now we're really confused??? Please help. My mechanic has been working on muscle cars since the 60's, he knows what he is doing! He adjusted these gears 3 times in one year and every time he says the clearance has changed dramatically. He says the gears are walking in the housing and is not really willing to put his name on this rear end! Can you actually get aftermarket gears that are 7.625, does it make a difference, my mechanic says it will! Someone PLEASE HELP!!!

RB83L69

7.5" & 7.625" are the same thing. No difference. That's why they're listed for all cars and trucks with this kind of rear, from 77 up to the present. They're all the same. They changed the pinion bearings (the head bearing specifically) in I think it was 80, and then the axle & side gear splines in about 89; but everything else is the same and always has been.

As far as the 3.08-down and 3.23-up thing, think for a minute about gear ratios. There's more to it than just the number of teeth; the diameters of the ring and pinion are in that same ratio too. I.e., in a 3.73 gear, the pinion is 1/3.73 of the ring diameter, but in a 2.73, the pinion is 1/2.73 of the ring diameter. The ring is always the same size in all ratios, about 7.6" in this model of rear; so as the ratio increases, the pinion diameter decreases. As a result, if you imagine taking a 4.10 gear set and installing it on a carrier, then take a 3.73 gear set and install it on the same carrier, the ring will be thicker since the pinion is smaller; a 3.42 will be a little thicker still; and a 3.23 even thicker. Eventually you get to a point where the gear is very expensive to make because thick things are difficult to heat-treat without them warping. So, they make a carrier with the flange moved over farther away from the pinion, and start over again with thin gears.

I have no clue who PTP is. But I can tell you that the Richmond drag-racing gears will always be noisier than stock gears; their teeth are cut differently, which is one of the ways they get added strength against shock loading. And they will never last as long as stock type gears on the street, because their metallurgy is different; they are made of a "softer" material, so that they absorb that shock load better, but their softness also causes them to wear out much faster in street duty. They are single-purpose racing parts, not suitable or appropriate for a daily driver.

I would recommend that you get rid of those; and put some Motive, US Gear, Precision, or Dana gears in it. You have a stock TPI motor, so you don't have anywhere near enough power to be bothered worrying about breaking the stock gears. Especially if the noise is a concern to you, those Richmonds are simply the wrong gears for you.

I think your mechanic will also have an easier time setting up stock gears; they almost always use a .035" pinion shim (in fact I've never yet taken apart a factory-built one of these and found any other thickness besides .035" in it), and then when the backlash is set to specs, it'll be quiet and reliable.

I would also strongly recommend against using the special thick gears, to put 3.23-up gears (3 series) on a 3.08-down (2 series) carrier. Use a spacer instead. The thick gears work fine as far as that goes, but will forever require you to run a 2-series carrier; whereas if you run the spacer, and you come across a 3-series posi someday, you can install it by just leaving the spacer out, instead of having to buy new gears.

my3rdgen

I also have the same PTP gears you have and I also got the 3:73 3:08 and down gearset and mine started out very noisy too. I have broken them in and then drained the crappy 80-90W and installed some Homogenizer oil (got it from work) that is an EP320 synthetic. Its close to a 120-140W heavy lube oil, this should quiet it down. I also made sure that the large holes that go to the axle tubes were not covered by the cover gasket.

Edit: I also added some additive for the posi. Also make sure that your mechanic is using the lash settings that are engraved on the pinion gear. They are not the same as the factory settings, my mechanic found this out the hard way too.

RB83L69

OOOppps, after re-reading that, I realize I got it backwards..... the 4.10 ring gear is thick, the 3.73 a little thinner, the 3.23 so thin that it can't be made any thinner; so they move the ring flange over away from the pinion centerline when they get to 3.08, so it's thick again; then the 2.73 is thinner, the 2.42 a little thinner, etc.

My apologies for confusing you.