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Gear Vendors under/overdrive auxiliary transmissions Hot Rods, GM 4

Time:2018-02-08 00:35Turbochargers information Click:

Gear a Under Vendors Overdrive

GM 4-Speed Automatics 700R4/4L60E/4L80E

There are two basic GM 4-Speed automatics: The light duty 700R4/4L60E found mainly in half ton and car applications, and the heavy duty 4L80E in the heavier applications.

Denny Terzich's, '56 Bel-Aire

700R4/4L60E’s have a low 3.06 first gear which is good for initial take off but this makes the transmission have the widest ratio changes of all popular makes and is the route of all the 4L60’s reliability and performance issues. The intention of the designers (a low starting gear and tall overdrive) was the best possible EPA ratings, which the trans does well but these wide ratios are a big compromise to performance and durability.

Even if you use forced induction (supercharging) on a 4L60 trans equipped vehicle it is hard to overcome the wide ratios. The vehicle cannot simply increase its vehicle speed 47% (the ratio split of the 1-2 shift) without pulling the motor rpm down a huge amount.Thus the more power you feed the 4L60 the more it converts to heat in its clutches and torque convertor. If you try to lock down the clutches without computerized torque management you break the transmission – there is jut no way to work well with stock ratios that are equivalent to skipping a gear (going from 1st to 3rd – skipping 2nd in an M21 manual is only 41%).

The GEAR VENDORS will give you Gear-Splitting to fix those wide ratios with a gear between each of them for tremendous gains in performance. Because of these wide factory ratios there is no better example of the difference that can be made with adding a Gear Vendors. See Final Drive Ratios. Gains of over 50 horsepower and 70lb ft. of torque are easily achieved just by having the close ratios when you need them.

The GEAR VENDORS also gives you an important towing or performance overdrive gear that is between the tall factory overdrive ratio (4th) and Drive (3rd). This gear will give you 11% more torque multiplication and the right rpm when you want instead of the torque converter locking and unlocking repeatedly or lugging the engine. When towing this gear will lower transmission temperatures by as much as 100 degrees when compared to factory overdrive. Cars and Trucks with 3.73 rear gears and higher (numerically) can also make use of double overdrive when not towing for 10-15% gains in MPG.

Warren Freitas's, '64 Nova

4L80E’s used in motorhomes and trucks have a .75 overdrive ratio very similar to GEAR VENDORS .78 but the factory unit tends to unlock and lock (hunt).The GEAR VENDORS will not hunt and will also reduce temperatures in the main transmission by as much as 100 degrees on warm days when towing. Consequently all our customers tow in the GV ratio and greatly extend the life of the trans.

Trucks running empty can make use of double overdrive for great economy and extended engine life. Motorhomes present too large a frontal area to the oncoming wind to make double overdrive practical but because they are always loaded they greatly need the GearSplitting and alternative Overdrive features of the GEAR VENDORS.

GearSplitting is the feature that allows the UNDER/OVERDRIVE to shift between the gears. You will now have approximately ½ the drop of engine rpm from one gear to the next when you want power. This is why a GEAR VENDORS will give you more power than any underdrive or overdrive on the market (see Common Questions). By keeping torque multiplication higher and engine rpm narrower you increase engine performance by typically more than 40hp and 60lb ft. of torque without any modification to the engine (see Final Drive Ratio charts and Horsepower and Torque curves), (see also Common Questions on performance modifications).

This is why big trucks (Kenworths etc.) use gears (most 18 wheelers have 15 to 21 gears) instead of engine modifications. Because gearing gives them performance which actually improves the reliability of the engine. The heavier you are loaded the more you need a GEAR VENDORS.

If you already have engine modifications (chips, exhaust, fuel increases, etc.) the GEAR VENDORS will let you get the most from them through working in narrower rpm ranges when loaded and also by adding torque multiplication to make it easier on the engine and transmission so as not to damage them with your improvements.

Walt Ast's, '57 Pontiac

The GEAR VENDORS comes with a 2-year unlimited mileage warranty (1 year on commercial applications) and a 30 day money back guarantee that you will love the performance (see Warranty for details). The GEAR VENDORS is the only aftermarket performance device or auxiliary transmission to come as original factory equipment on new cars, trucks, vans or motorhomes. Over 1 million in the 80’s and 90’s were installed by manufacturers on vehicles; ie: Ford Diesel Transit Vans (european market), Volvo gas and diesel, Fleetwood, Allegro, Rexhall, Monaco and other motorhomes and GM’s Twin Turbo Callaway Corvette.

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