GO­ING ON OVER­DRIVE

A 700-R4 trans­mis­sion ca­pa­ble of big-block dura­bil­ity

Chevy High Performance - - Con­tents - TEXT & PHO­TOS Jim Smart

A 700-R4 trans­mis­sion ca­pa­ble of big-block dura­bil­ity

It­was a mat­ter of ne­ces­sity the GM Turbo-Hy­dra­matic 700-R4 trans­mis­sion ever hap­pened at all. GM’s pow­er­train en­gi­neers were handed a chal­lenge amid higher fuel prices and tougher gov­ern­ment stan­dards to im­prove fuel con­sump­tion with an old-time proven con­cept called over­drive. GM took the Turbo 350’s proven in­ter­nals and adapted them to a new pack­age known as the 700-R4 over­drive au­to­matic.

When the 700-R4 was in­tro­duced in 1982, it had mi­nor per­for­mance is­sues GM en­gi­neers had to work through. Just five years later, the 700-R4 had un­der­gone sev­eral en­gi­neer­ing re­fine­ments and gained a more fa­vor­able rep­u­ta­tion with en­thu­si­asts. By 1990, the 700-R4 be­came a pop­u­lar swap for the clas­sic Turbo 350. That same year, the 700-R4 be­came known as the 4L60, the same trans­mis­sion, but with a new des­ig­na­tion. In 1993, the 4L60 be­came elec­tron­i­cally con­trolled and known as the 4L60E. Even though the 700-R4 trans­mis­sion isn’t be­ing man­u­fac­tured by GM any­more, it re­mains one of the best trans­mis­sions around.

Zack Farah founded Gearstar Per­for­mance Trans­mis­sions to pro­fes­sion­ally serve hard-core en­thu­si­asts. His goal, based on decades of ex­pe­ri­ence in the mass-pro­duc­tion trans­mis­sion re­build­ing in­dus­try, was to be the best cus­tom au­to­matic trans­mis­sion shop in the in­dus­try.

“Gearstar is a cus­tom trans­mis­sion shop, one trans­mis­sion, one builder, start to fin­ish,”

Zack com­ments. “We cus­tom man­u­fac­ture each trans­mis­sion to the ex­act ap­pli­ca­tion, mean­ing how the car is go­ing to be driven, spec­i­fi­ca­tions, horse­power and torque, ve­hi­cle weight, rear axle ra­tio, and rear tire size.” He adds, “We cal­i­brate shift points and set red­line pa­ram­e­ters. We also set up the cor­rect speedome­ter drive and

driven gears so the speedome­ter is 100-per­cent ac­cu­rate. We also build the trans­mis­sion to have a firm, hard, or very hard shift, de­pend­ing on the cus­tomer’s pref­er­ence.”

Gearstar builds a wide va­ri­ety of 700-R4 trans­mis­sions—five of them—rang­ing from 325 to 600 lb-ft of torque ca­pac­ity. Be­cause the 700-R4 can easily over­heat, it gets Gearstar’s clos­est at­ten­tion in terms of cool­ing and dura­bil­ity. Over­heat­ing is one of the great­est causes of trans­mis­sion fail­ure.

We’re putting a Gearstar 700R4 Level 4 be­hind a Chevro­let Per­for­mance ZZ454 big-block crate engine, sport­ing 440 horse­power and 500 lb-ft of torque, in a ’67 Chev­elle. The Gearstar 700-R4 is up to the task for this engine, and any fu­ture horse­power and torque in­creases.

“In this case, we built a street/ strip pack­age with au­tocross­ing in mind,” Zack tells us. “Each trans­mis­sion and con­verter is dynotested as a pack­age the equiv­a­lent of 100 miles on the street. When you re­ceive the trans­mis­sion it has 8 quarts of ATF in the trans­mis­sion and con­verter. This is not just an­other off-the-shelf 700-R4.”

The Gearstar Level 4 700-R4 sports a heavy-duty, re­in­forced cast-alu­minum case. Gearstar loads it with its best Mas­ter Over­haul Kit with Raybestos Gen­er­a­tion II Rac­ing Fric­tions and hard­ened Ko­lene steels, wide car­bon-fiber 2-4 band with a heavy-duty band an­chor.

The 700-R4’s valve­body gets a Tran­sGo Re­cal­i­bra­tion Shift Kit with Shift Com­mand and new valve­body sep­a­ra­tor plate with orig­i­nal equip­ment-style fil­ter.

Zack adds, “This 700-R4 trans­mis­sion build for Hot Rod Spe­cial­ties in­cludes the up­grade to a Smart-Tech Drum and in­put hous­ing kit with the heavy-duty hard­ened in­put shaft. We can reg­u­late line pres­sure un­der a high­torque load and you get in­creased clutch ca­pac­ity.” Zack goes on to say, “Our 2.84:1 in­put car­rier kit trans­forms the pop­u­lar 4L60 se­ries trans­mis­sion from the fac­tory ‘wide ra­tio’ 3.06/1.63 to a ‘close ra­tio’ 2.84/1.55 for game-chang­ing ac­cel­er­a­tion on the track. This keeps per­for­mance en­gines in the op­ti­mal power­band while al­low­ing a longer pull in First and Se­cond gears, im­prov­ing consistency, re­li­a­bil­ity, and per­for­mance.”

Gearstar fit this 700-R4 with cus­tom-ma­chined Se­cond-gear servo and Fourth-gear su­per hold servo, new Tor­ring­ton bear­ings, bush­ings, thrust wash­ers, new 29-el­e­ment dual cage sprag, new low-re­verse spring and roller clutch, high-ca­pac­ity 10-vane front pump assembly with new ro­tor and slide, hard­ened sta­tor shaft, new vanes and hard­ened rings, 0.500 boost valve, up­dated pres­sure reg­u­la­tor valve, re­in­forced in­put drum, ex­tra ca­pac­ity 3-4 clutch drum assembly

with high-rev spring kit, heavy-duty hard­ened rol­ler­ized sun shell, fivepin­ion heavy-duty steel plan­e­tary gearsets, fully rol­ler­ized plan­e­tary gearset, new orig­i­nal equip­ment steel trans­mis­sion pan, new speedome­ter drive, and driven gears.

Gearstar im­proves dura­bil­ity with a 30,000-pound gross ve­hi­cle weight Hay­den trans­mis­sion cooler and vac­uum/elec­tric torque con­verter lock-up sys­tem for greater efficiency.

We took a clas­sic ’67 Chev­elle and swapped out a Turbo 400 for the late-model efficiency of a Gearstar 700-R4 over­drive au­to­matic and were pleased at how easy this swap was. All it took was the same flex­plate, a slight ad­just­ment to the cross­mem­ber, and a mild TCI shifter de­tent re­place­ment and we were back in the game.

Joel Rode at Hot Rod Spe­cial­ties in Up­land, Cal­i­for­nia, per­formed this swap in a mat­ter of hours and was driv­ing the Chev­elle the next day.

WHAT WE LEARNED

When Joel took the Chev­elle out for a road test, he was pleas­antly sur­prised at the crisp per­for­mance of Gearstar’s 700-R4 Level 4 trans­mis­sion. “The shifts are per­fect,” Joel com­mented. “I drove the Chev­elle home and have to say the 700-R4 is pretty badass. It shifts right on time with my shift light all by it­self with­out man­u­ally shift­ing.

All I have do is point and take a stab at it.”

Joel drag-tested the car with the 700-R4 and came up with a 12.43 e.t. at 107.8 mph. When he took the car to GTR High Per­for­mance for dyno test­ing, he broke the 12-bolt dif­fer­en­tial, which tells us plenty about the fierce dura­bil­ity of the Gearstar trans­mis­sion. It sur­vived the dragstrip and the pu­n­ish­ment of a dyno ses­sion.

With the Turbo 400 trans­mis­sion, Joel ex­pe­ri­enced 362.34 hp and 381.83 lb-ft of torque at the rollers. Al­though the 700-R4 con­sumed power, it stayed to­gether with 344.24 hp and 372.49 lb-ft of torque at the wheels. That in­di­cates a loss of around 18 hp and 9 lb-ft of torque. What does this mean for you in the real world? Suc­cess comes to those who fin­ish the race, not those with hard luck sto­ries and failed trans­mis­sion tales to tell. The Gearstar 700-R4 gives you real efficiency on the street where you drive most and proven dura­bil­ity when it’s time to go rac­ing. CHP

04 | The Turbo 400’s im­pos­ing de­meanor is re­flec­tive of its brute rugged­ness. There’s a slight weight gain with the 700-R4, which tips the scales at 155 pounds ver­sus the 400’s 134. How­ever, both trans­mis­sions are roughly the same size with near match­ing cross­mem­ber align­ment. The cross­mem­ber has to be moved slightly aft.

05 | Here’s the Gearstar 700-R4 over­drive au­to­matic on a sling ready to in­stall. Sum­mit Rac­ing Equip­ment has pro­vided ev­ery­thing else we need for this swap. In­land Em­pire Driv­e­line Ser­vice is set­ting us up with a cus­tom-made drive­shaft to con­nect the trans­mis­sion.

03 | The Turbo 400 is sup­ported with a trans­mis­sion jack for re­moval. Be­cause the Gearstar 700-R4 has sim­i­lar di­men­sions to the Turbo 400, it is easy to swap with­out ex­ten­sive mod­i­fi­ca­tions. Gearstar and Sum­mit Rac­ing Equip­ment have pro­vided vir­tu­ally ev­ery­thing nec­es­sary to do this swap.

02 | Re­moval of the Turbo 400 be­gins with re­mov­ing bell­hous­ing bolts and dis­con­nect­ing the torque con­verter up front, shift link­age, and vac­uum mod­u­la­tor. And fi­nally, the trans­mis­sion cross­mem­ber and drive­shaft are re­moved, as shown.

01 | Chevro­let’s Turbo 400 trans­mis­sion is a time-proven rugged per­former. It can take the power. How­ever, it is not an ef­fi­cient au­to­matic trans­mis­sion for cruis­ing. We’re go­ing to re­place it with a fuel-ef­fi­cient Gearstar 700-R4.

07 | What makes the Turbo 400 dif­fer­ent from the 700-R4 is shift mo­du­la­tion. The Turbo 400 re­lies on vac­uum mo­du­la­tion based on throt­tle po­si­tion and load, which af­fect man­i­fold vac­uum. Shift mo­du­la­tion is also con­trolled by out­put shaft speed. The vac­uum mod­u­la­tor is fully ad­justable to con­trol shift points and firm­ness.

06 | GM’s Turbo 400 (top) and Gearstar’s 700-R4 are po­si­tioned side-by-side. As you can see, both sport sim­i­lar di­men­sions. The Turbo 400 is ac­tu­ally lighter by 21 pounds. What you gain in efficiency with the 700-R4 beats the 400’s weight ad­van­tage.

08 | The 700-R4 looks to this throt­tle valve (TV) ca­ble to mod­u­late shift con­trol and firm­ness. In­stead of re­ly­ing on in­take man­i­fold vac­uum to con­trol shift mo­du­la­tion, the 700-R4 goes on throt­tle po­si­tion and out­put shaft speed.

09 | When you in­stall the throt­tle-valve (TV) ca­ble, Joel sug­gests mov­ing the ca­ble all the way out and lock­ing the ad­just­ment in as shown. This ap­proach makes the ca­ble eas­ier to con­nect at the throt­tle valve.

10 | With the ca­ble locked, it’s eas­ier to con­nect this link to the throt­tle valve.

11 | Joel took the lib­erty of re­mov­ing the 168-tooth flex­plate, which fits both the Turbo 400 and the 700-R4, to check the in­tegrity of the rear main seal. If you’re go­ing to fix a rear main seal leak, now is the time to do it. Joel will re­in­stall the flex­plate us­ing a thread locker and torque wrench. Flex­plate bolt torque is 75-85 ft-lb in a criss­cross fashion in one-third val­ues us­ing Per­ma­tex Thread­locker.

12 | The 700-R4 is at home on the same flex­plate as a Turbo 400, which makes this an easy swap. This is the 168-tooth flex­plate for both the Turbo 400 and 700-R4 and an 11 1/2-inch bolt-cir­cle torque con­verter.

13 | Gearstar has fit­ted our 700-R4 with a Yank Per­for­mance torque con­verter of­fer­ing a 3,200-stall speed for crisp street/strip per­for­mance. This is a big-block Chev­elle born for the com­mute, which is also ready for the weekend au­tocross or dragstrip.

14 | Joel guides the 700-R4 into place. This Level 4 700-R4 trans­mis­sion sports a whop­ping 600 lb-ft of torque ca­pac­ity, which means Joel can build more power into the 454.

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