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guestperson 02-28-2002 08:06 AM

shifting hard
checking out a car for the secretary at work. she has an 87 Firebird. She says when she checks the tranny fluid it looks a bit high. she took a trip i guess a while back and it was burning oil. now she says that the car is shifting kinda hard. any ideas?

NOVA JEFF 03-11-2002 08:31 AM

Need more info,what trans is in vehicle? Suggestions! Ck for trans leaks if loosing fluid, repair. If trans has kickdown cable could be streched or out of adjustment,if trans has vaccumn modulator, it could be defective allowing trans fluid to be sucked up through vacumn line to intake manifold and burning the fluid through exhaust,pull line ck for fluid,vac line may be cracked insufficient vac. or modulator is bad


ragona 03-13-2002 10:49 AM

Is it a big deal to change the modulator on a th350 ?

NOVA JEFF 03-15-2002 08:45 AM

NO, Look under car passenger side toward rear of trans, look above back of trans pan,metal looking bulb with line hooked to it. REMOVALE unhook vacumn line . There is one bolt 13-14mm. Remove the bolt and modulator metal retainer, pull mod. out of the hole. If possile take to part store get new 350 modulator AUTO-ZONE $10-$15 ect. Take new mod. from box,new O-ring seal in box or on mod. look at old mod to verify correct. Look in vac line hole on new mod ck for adjustment screw.Will get to that after installed. INSTALLING NEW MOD. clean area where old mod removed, lube seal with tran fluid. Take new mod. push into hole, will feel spring tension NORMAL,push mod all the way in while holding in install metal retainer bracket & bolt. Tighten bolt till bracket & mod.seated all the way, give bolt Quarter turn DON'T OVER TIGHTEN. Hook up vacumn line ,start car ck for leaks,OK,ck trans level hot in park eng running top off to fill hot if low. Test drive car observe how it shifts if it feels soft or hard when trans shift. If it feels comfortable your done, if not MODULATOR ADJUSTMENT,IF HAD ADJUSTSCREW IN VAC opening of NEW MOD, INSTUCTION should be on paper in box with new MOD.It will tell you how to adj. the mod turn screw in or out upon the harsh or soft shift test drive after an adjustmemt at casuall intown speeds & heavy accelleration.Hope this helps, let me know.


gordon kitson 03-16-2002 11:17 AM

when working at chevy dealership we had to change the fluid and filter if posible drain the toruce converter and change the fluid when changing fluid check old fluid for a lot of metal shavings there should be a magnect drain plug check for over amount of metal shaving the tranny may be gone i dont think so.gordon

69 Firebird 03-16-2002 08:58 PM

For your 87 firebird, the trans is a 700R4. The hard shift can be by modification (i.e. BM shift kit) or anomaly. If by anomaly, 2 potential suspects: detent misadjusted or governor valve sticking. Both will cause a late, hard shift. To adjust detent cable, locate detent cable at bracket on intake manifold. There is a "wedge" in the section of the cable immediately behind the bracket. Pull out on the wedge with a screwdriver. Move throttle to wide open and push wedge back in. If it iss the governor, remove housing cover at left rear of trans. Remove governor. Valve runs through center of governor. Check for freedom of valve movement. if stuck, remove roll pin at nylon gear and remove gear. Extract valve by puching on it from between flyweights. Clean assembly with brake or carb cleaner. If it sticks again after reassembly and driving, trans is probably trashing out and will need rebuilt.

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