When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I got my 373's in today. 3 days but lost a day because we got hit with 15" of snow yesterday so no trucks were on the road. These are the real deal with the logo on the RG, made in the usa and this set dated Dec 2016- sitting for 4 years so all the old stock is being sold off now. The word is out now so they won't around much longer.
I found that both Zip Corvette and VanSteel have US Gears in stock, but I would recommend verifying it by phone before ordering online. VanSteel provided a forum discount and I ordered a 336 gear set today; made by US Gear.
I just called Strange Engineering to get an update. They did say the sets are on back order but the have them coming today from a supplier. My receipt does indicate US gears, They should receive them today once inspected they should ship as soon as tomorrow. Description GM 8.4 Corvette 3.73 Gear Set US/Strange Gear - Produced in USA
Item# RS01884373C
GM 8.4 Corvette 3.36 Gear Set US/Strange Gear - Produced in USA
Item# RS01884336C
GM 8.4 Corvette 3.55 Gear Set US/Strange Gear - Produced in USA
Item# RS01884355C
1966 big block posi. Here’s a gear head question. If I have (4:11) and want to change to 3:73 or 3:55 do I need a different carrier?
thanks in advance.
They are still out there but once the stock is depleated that will be it, unless US Gear changes and starts up again. Since they were bought out I personally doubt that will happen but who knows. I spoke to another person in the business today and they confirmed they stopped making them. Once you get them look at the date code to see if it's NOS like I got in.
411 and 4 series gears were installed on a 4 series posi case which has a thicker flange then a 3 series case. The old trick when going from a 3 to 4 series gear was to use a spacer between the 4 series gear and flange. The problem with that is the ring gear bolts loosen up over time and that was the end of the diff once it locked up and broke everything inside.
Tom has US Gear made a thick ring gear to use 4 series ratios on 3 series cases without a problem. It basically obsoleted the 4 series posi cases as fewer and fewer guys want 4 series gears for a street car now.
So a 66 BB posi case setup with 411's would be a 4 series case and yes you need a 3 series case for 373 or any 3 series gear- UNLESS someone was in there over the past 20 years and installed a 411thick on a 3 series case.
Add to that 65-68 Eaton cases were not the best and prone to cracking. You are best looking for a good use 72-79 vette Eaton posi, NOS GM, or lastly a new loaded (imported) posi - there are 2 new on the market today that I am aware of. They are ok but I don't use the clutches or spiders, although the Eaton spiders are now about the best you will find new. NOS Tom's spiders are the best if you can find them.
I used a set of the US Gears 3.73 Lightning on a new buildup semi-recently. That build is in the car and runs great so far. I haven't abused it yet though. I went to rebuild the rear I took out for a spare and ordered another set from Summit. The gears were on backorder for a few months, finally came in and were not in a Lightning box. The pinion gear had light rust on the end, but more problematically they didn't have a depth measurement anywhere on them. The first set had the measurement in white paint on the pinion gear. Looks kind of like they sent a regular gear set off to be polished and didn't scribe or paint the depth measurement back on. I sent them back and ordered a set of the REM polished Eaton gears. Those were backordered too. I ordered them in early November and they have a 1/10/21 anticipated ship date (which has been bumped twice already). I'm in no particular hurry though since it is just a spare rear.
I have setup several Lightning sets and the depth dimension wasn't on any of them that I recall. I go by pattern setup so it wasn't a problem. At this point I recommend getting a gear set, you can always have them REM polished by a company with the equipment or go direct to REM in CT. They are going to be harder to get unless things change, Lightning series have been harder to get in the recent past suggesting vendor issues or lack of stock.
Good to know you can use the pattern alone as a guide. I read that the gears were pre-run and since the tolerance was so tight (+/- 0.002") on the depth setting per their instructions, I was worried that they would make noise if I deviated too far from that dimension. That was my first rear setup, so I was being pretty careful. Sounds like there might be a little more room for error as long as the pattern is correct.
All ring and pinion gears are matched sets that have been lapped on a machine. One reason buying used gears can be tricky if someone mixed gears to make a sale.
As you know getting a pattern on the polished gears is not as sharp as standard gears but you can still get a pattern with equal length between the root and crown and US Gear typically sets up center to toe, sometimes center but most are center to toe.
Here is a set I just setup, the surface was so smooth I had to work the paste consistency a little. If this was a standard set the pattern would be a lot sharper but they are dialed in.
I just ordered a set of 373's to see how long it takes to get them and because they are the most common ratio I have used in the last 20 years. I will use them so I have no concerns. I only saw 355's - 4 left when I was online, and 373's. I had a set of NOS Tom's 308's that I used a few months ago, they are probably long gone now.
Expect to see the prices skyrocket on the remaining ones now. Those that have a rebuilder replace the gears I would strongly recommend you ask whose gears and get a picture of them and the final pattern.
As for what brand to order I would do my homework before ordering any gear set at this point. If I was looking for 308's I would still be looking for US Gears. I would personally pay more for them since they aren't coming back unless Meritor changes their mind, doubtful. Now it could be my source was incorrect but that source is highly reliable.
Will anyone step up and make vette gears like US Gear did? I can't say but I can say US Gear stopped making the 10-17x30 spiders for Tom about 10 years ago, and I haven't seen any others like those since. There was more of a market 10 years then there is today, what about 5 years from now? In the case of those spiders they are the same as used in the chevy 12 bolts so there was a much larger window of sales available rather then just vettes with Eaton posi's and they still haven't been made. There are some on the market, one brand is decent and I would use but they are not at the level of what Tom sold. The other brand, I have seen QC issues with and would not use.
GTR1999. Looking to replace my Gear Set in my recently purchased1979 which has 3.55 ratio. I'm doing a complete rebuild of suspension and differential this cold Canadian winter. An over abundance of information on gear sets is overwhelming. An acquaintance of ours in Oakville Ont. Ca. told me that you are the differential Guru. I'm currently looking at a U.S. gear set at summit Racing. 1979 CHEVROLET CORVETTE US Gear 01-884355C US Gear Ring and Pinion Gear Sets | Summit Racing. It lists mid January as a shipping date. Would you recommend this set or another. I'm also in the market for a rebuild kit using Timken bearings as well as a Posi Pak. Do you have any suggestions? I know this may be a burden on your time but I would like to do it right the first time around. So far I have received new a new Timken Bearing spindle install kit with shims and installation set up tool. New spindles and yoke shafts are in transit. Any thoughts/help would be greatly appreciated. John
Just a heads up on Summit. I ordered some US Gear 3:55 for a 9 inch Ford and they told me whatever they have in stock is it and they will not be getting anymore.
Man oh man.... can you feel the regret by me here for not having researched this topic sooner????
My rear diff rebuild has been on a slow roll due to my rebuilders health problems last year, so we didn't get around to discussing rear gears until earlier this year and I went to Tom's to order everything.... They had ordered 10 sets of 01-884336 gears from US Gear in March and were told that was the last of 40-50 sets they built. Sitting around through April because everything now takes forever lately to ship/receive and I got a call from Tom's last week that when their Pallet showed up it was sans the 3:36's they ordered.
I researched and learned the last 9 sets shipped out of US Gear in February to Moser who attests that they just passed them through to someone else....
I've called several well-known and not so well-known Corvette and Diff folks as well as suppliers and have hit dry wells. Thought Strange was going to come through as they still have 01-884336C on their website and they took my cc and everything only to call yesterday and tell me "sorry"...So now I am at the tail end of what's turned into an almost 2 yr rebuild (the car is a frame off endeavor) and cannot find a decent set of 3:36 rear gears... Has to be 3:36 as this car is an L82 4 spd and was one of only 382 cars ordered that year with that rear gear.
I've heard not so wonderful things about the most prevalent gear available, Richmond and I had one very reputable Corvette parts supplier tell me he had 10 sets of gears (OEM unknown) in stock(he still does) only to confirm they now come from China... no thanks!
US Gear's bean counters have left the hobby in a lurch and I was caught off-guard because this was not the Corvette problem- du Jour 6 mos ago when this whole mess started to unravel per what I am now reading...
