Ok folks tossing the idea about gearing my 8.5 down a little lower so just looking for insight, tips, tricks, etc. Never done this before but I don't see why I can't acomplish it.
rear gear swap info
- Thread starter mebe007
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I have a one-legger GN axle with 3.42s. I am in debate about dropping in a used G80 posi I have from a 1979 K10 that had the stock 8.5 axle, and just keeping the 3.42s that have 80K on them. Your thoughts?
The 3.42 is great but with having a clutch I want to get my first gear ratio up closer to the 10 mark. Makes life easier on the clutch and my life easier around town. And possibly a little quicker provided I can hook
I bought a Tremec TKO 600 (TCET5009) about 6 years ago - has the 2.87 first gear. With 3.73 I calculate 10.7 and with 3.42 I get 9.8. The 0.63 overdrive gets 2.15 with 3.42 and 2.34 with 3.73. But, we have a 75 mph speed limit out here.
Which way would you go?
Which way would you go?
With the OD I would be all over the 3.73 without a doubt I plant to install 3.90 gears. I don't have OD but I don't really drive it on the highway. It's all around tow, through the country or trailer to the track
If this gear change is going to be a one time event you might want to consider finding someone to do it. It's not a difficult job but if you don't have the tools it gets expensive to buy them. You should be able to get it done for about $100
you can get a dial indicator used for pretty cheap. Since you'll be heading to the track you might want to consider using spacers and shims to get your preload instead of a crush sleeve
I think you will want to do it yourself. Please read a factory manual until your head hurts and you grasp the concept. The correct tools are very expensive and even with them it's a time consuming headache of a job. But there are cheaper models available like at JEGS, Speedway, and other places. Basically it's a pinion depth setting tool, a dial indicator with magnetic stand, and a set of feeler gauges that go down to .001". It's best to start with an all new bearing, seal, and shim kit. As far as the pinion depth, I have always said that whenever I checked it, the required shim was always either exactly the same as the factory shim, or one or two thousandths up or down. So if it's not chewed up, you could probably just leave the factory pinion gear shim in place and go from there. That eliminates the depth setting tool. The carrier shims are where the big changes occur. No matter what ratio you choose, that will change the ring gear carrier position. The factory assesses this to .000" clearance, adds .004" pre-load each side, sets backlash, and then selects a cast iron shim exactly as thick as is needed and it is pressed into place. We cannot do this and even if we had a selection of cast iron shims to choose from, banging them in with a BFH risks cracking them. Thus we use a steel shim pack that is made up of various thicknesses to get to the exact thickness needed. The better kits come with a shim holder that keeps them in place to ease installation. The feeler gauge is used to check the clearance between the carrier bearing race and the case, you need to get it to .000", meaning where a .001" feeler won't quite fit. . The dial indicator is used to measure backlash between the pinion and ring gears, the magnetic stand makes it easy to mount and position the tool. Changing the carrier shim thicknesses an equal amount moves the carrier closer to or farther from the pinion gear which changes backlash. So you are doing two things at once, getting the ring gear carrier into the carrier housing with .000" clearance then adding .004" to each side making .008" pre-load, and getting the backlash at .008" or whatever is specified for your application. Be assured this takes many attempts to accomplish and can be very frustrating. But when it's dead on you have a rear end that will last 100K quietly and you will now possess a valuable and rare skill.
and i thought y head was spinning before with all the reading ive been doing. any recomendations on brand of gears?
btw ive heard the stock pinion shim being right over 90% of the time from quite a few folks
btw ive heard the stock pinion shim being right over 90% of the time from quite a few folks
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