GM TH700-R4 Transmission Rebuild - The 700 Club

Monster 700-R4 Rebuild

Sean Haggai Feb 8, 2011 0 Comment(s)
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Getting the best out of something usually means taking something else out of the equation to get it; a little give and take, if you will. For instance, in order to get a small-block to create big-block-like grunt would require a camshaft spec so big, it would be nearly impossible to drive on a daily basis. Adding steeper rearend gears will help accelerate your car harder at the lights, but it wouldn’t make for an ideal cruiser during sustained freeway hauls. Traditionally, the same adage went with automatic transmissions too; they were either great at the track or on the street, but never both.

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Automatic transmissions, namely the GM TH700-R4, were widely used and often found in LT-1powered Corvettes to work trucks. Unfortunately, these were never known for their strength and would tend to self destruct with any significant amount of horsepower. On the other hand, their First and Second gear (3.06:1, 1.63:1) ratios are lower than the gears found in the more common TH350 and TH400. This made First and Second gear shifts much quicker, ultimately helping to accelerate the vehicle. Added features included lighter internal components, which created less drag on the engine, and add in the overdriven Fourth gear with a 0.70:1 ratio and the 700-R4 had the great potential for increased fuel economy.

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If you’re looking to install one for yourself, but worried about its inherent weaknesses you’ll be happy to know that Monster Transmissions has the solution. These days, it’s possible to have a smooth, durable, and strong four-speed transmission that can handle the added power, all the while providing lightning quick and positive shifts at the track. To do this, Monster Transmissions packs some serious gear when it comes to retrofitting these four-speeds. Monster’s Monster-In-a-Box kit came with everything we needed to rebuild our 700, including the five-pin front and rear planetary gear sets, a Corvette Second gear servo, Teflon pump bushings, superior shift reprogramming kit, heavy-duty sprag, and a chrome pan. It even came with all the incidentals like the gaskets, seal, and O-rings. Should you need a converter, Monster can supply that too. In our case, we added a 2,600-2,800 stall torque converter.

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To get it all done correctly, we headed over to Reb’s Specialites in Reseda, California, where Brian Kardell tore the transmission down to the case, cleaned all the reusable components and installed the entire Monster kit.

Master Overhaul Kit

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The SS Mega Monster rebuild kit includes:
-Rear heavy-duty five-pinion planetary
-Front heavy-duty five-pinion planetary
- Chrome transmission pan with drain plug
-Gaskets
-O-rings
-Lip seals
-Sealing rings
-700-R4 Corvette Second gear servo
-700-R4 billet servo Fourth gear and cover
-0.500 boost valve
-Alto Kolene steel kit
-Alto Red Eagle clutch kit
-700-R4 filter
-700-R4 Alto wide high-performance band
-Teflon pump bushing
-Delco front seal retainer clip
-700-R4 Superior shift reprogramming kit
-Hardened pump rings
-700-R4 10 Vane rotor gear
-700-R4 10 Vane rotor guide
-700-R4 high-rev Vanes
-700-R4 heavy-duty throttle valvespring
-Heavy-duty Beast sun shell
-Heavy-duty 28 element Sprag

Five-pin Front & Rear Planetary Gear

Both the front and rear planetary gears are substantially larger and stronger than the factory 700-R4 units from GM. While the factory units only had four pinions, the Monster units have five. The additional pinion allows for a greater load capacity and increases its strength.

Monster Servo
In the transmission, servos serve as a direct link between increasing pressure to hold power and to reduce slippage. Monster supplies two servos, one for Second gear and another for Fourth, and they both apply the band onto the direct drum. Both supplied servos have larger piston diameters than the factory, which allow for more clamping force for the band to the drum.

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