Thread: Gear Ratio

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What would be best for the diff a Limited Slip or a Posi Trac. I’m not planning on racing it but still would like to race it on occasions.

Thanks for all of your help with this i appricate it.

Originally Posted by 1972chevy

What would be best for the diff a Limited Slip or a Posi Trac. I’m not planning on racing it but still would like to race it on occasions.

Thanks for all of your help with this i appricate it.

Limited Slip and PosiTrac are just two names for the same thing, a clutch pack type carrier to bias the load to the wheel with the best traction http://en.wikipedia.org/wiki/Limited-slip_differential. They are subject to clutch wear over time, and require the addition of a friction additive to the differential. To improve upon that you might consider an Eaton/Detroit TrueTrac, which is a spiral gear locker that is pretty much bullet proof, IMO - Performance Products | Detroit Truetrac Differentials They launch straight & true, no side slip at all, and require no special additives.

Changing your gear ratio would be as easy as just changing out rear axle, chevy trucks starting in `67 started using friendlier ratios, 60 to 66 most ratios were 4.11 and 3.73, posi and non posi, other ratios were 3.42 and 3.08 but not common place 67 to 69 will have the same axle track width as the `64, `70 to `72 will be one inch wider on the axle width and started using 5-lug as opposed to 6-lug, there will also be a change in the track bar configuration but can be fixed by buying from POL, LMC or ECE truck sites, you never did say whether you have 6-lug or what ratio/posi you have now.