Just curious as to how they're working out there in the real world. Not entirely too sure how they work and someone today was talking about the improved fuel mileage and acceleration with the "additional" gears.
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Oct. 22, 2008 10:46 p.m. Duende New Reader
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Oct. 22, 2008 10:50 p.m. Strizzo Dork
huh?
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Oct. 22, 2008 11:29 p.m. HappyAndy New Reader
are you talking about the planetery gear driven over drive unit that stacks onto the back of a regular transmision? I have no experience with them, but if that is what you are talking about, they have been around for a long time.
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Oct. 23, 2008 5:58 a.m. ignorant SuperDork
Never used one, but well regarded in the towing scene. It's a gear splittler and the concept is rather proven.
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Oct. 23, 2008 1:22 p.m. Evan_R New Reader
No question they do work. It's licensed (and modernized!) version of the Laycock de Normanville overdrive unit found on countless LBC & Volvos.
Thing is, the kits start around $1800 and then you've got to pay to get your driiveshaft shortened. For that dough, you'll need to save a LOT of fuel.
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Oct. 24, 2008 11:49 a.m. curtis73 Reader
I had one for years in a 66 Bonneville tow rig. I never had a load of luck with saving fuel with 508 cubes and an 800 cfm carb, but it was bulletproof. I chose it for several reasons. I towed a lot with that car and I needed an OD that I could tow with. For about $2000 I could have bought a 4L80E, adapted it to the Caddy 500, and run a computer. But, I couldn't tow in OD. Instead (for about $2000) I ran the GVOD which can run all day towing, plus I had the added engineering simplicity of the mechanical tranny instead of a 4L80E that required sensors, wiring, computer, and all kinds of junk.
They are used behind the Scheid Diesel dragster that puts out somewhere north of 3600 lb-ft of torque through a 4.6:1 Lenco first gear. That is 16560 lb ft of torque and its gone down the track several hundred times.
They really are an intensely robust unit. Shifting is firm, like a TH400 with a shift kit. You can fine tune the shift firmness by deviating from the recommended oil viscosity, but you run the risk of additional wear.
Really killer unit. Is it worth it? Maybe. I think its market weakness is that its TOO much overkill. Its way to much fuss, strength, and cost to have a real place in the market.
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Oct. 24, 2008 12:41 p.m. Travis_K Reader
Is there any truth to what I have heard from several people that going downhill with a heavy load and letting compression braking slow you down will quickly fry the gear vendors unit? Other than that I havent ever heard anything bad about them.
