Oil Pan Back seal & Backlash...

Rosco · 10-28-2003, 05:53 PM

Ok, well i took my car to a shop today to get it looked at due to leaking oil on the back of the engine. I was told that the rear seal on the oil pan is leaking oil. Is it necessary to drop out the oil pan to put a new seal on it?

Also, the tech left a note in my car about the rear-end having about 1/4" of backlash in it. I never got a chance to talk to the mechanic due to me getting out of work so late. I was wondering what this actually means and what it deals with in the rear-end. I know somewhat that it means the driveshaft is able to move in the opposite turning direction, but what does this mean for the rear-end?

andy669 · 10-29-2003, 06:44 PM

Chances are the oil leak is from the rear main.

Backlash is the measured distance the ring gear will rotate without the moving the pinion. Basically its the distance between teeth of the ring and pinion. Normal is around .018". If all the tech is doing is rotation the driveshaft and saying theres 1/4 inch of backlash, hes an idiot. Being able to rotate the driveshaft 1/4 inch is normal. Was the rearend making alot of noise?

Andy

302 LX Eric · 10-30-2003, 02:39 PM

Andy's right on.

Just to add a little bit to the above...you want to make sure that the backlash is set w/in tolerance or else you'll get excessive gear wine and wear - or possible breakage. It's an easy thing to measure with a dial gauge mounted to a magnetic stand: just place the dial gauge on perpendicular to one of the teeth on the ring gear and measure how much movement occurs (back and forth) while the pinion is stationary. Adding or removing shims from one side of the carrier to the other and vice-verse will either increase / decrease the amount of backlash.

But, as stated above, turning the driveshaft a 1/4 inch either way is normal....I wouldn't trust this 'mechanic'.

E

Rosco · 10-30-2003, 06:06 PM

Thing about the oil leak..I really don't think it's the rear main. That was replaced less then 15k ago. Yeah, the mechanic said i should be able to hear noise coming from the rear-end if there was alot of backlash, I haven't heard a thing. I guess i'll just have a shop look at the axle when they install my gears. Thanks alot guys

andy669 · 10-30-2003, 10:04 PM

Eric did a better job of describing it. If you are putting new gears in they will check the backlash when they install them. I'm guessing everything is normal now.

As for the oil leak, its not going to be easy either way. Replacing the pan gasket isnt easy. Personally, I'd rather pull the trans and change the rear main again, then replace the pan gasket.

Andy

Rosco · 11-03-2003, 06:03 PM

Dropping the pan shouldn't be that bad of a problem, but i do have to replace the gasket, and both front and rear seals on the oil pan. Is there anything i should look into changing as well?

10-28-2003, 05:53 PM	#1
Rosco Registered Member Join Date: Mar 2002 Location: Vestal, NY Posts: 307	Oil Pan Back seal & Backlash... Ok, well i took my car to a shop today to get it looked at due to leaking oil on the back of the engine. I was told that the rear seal on the oil pan is leaking oil. Is it necessary to drop out the oil pan to put a new seal on it? Also, the tech left a note in my car about the rear-end having about 1/4" of backlash in it. I never got a chance to talk to the mechanic due to me getting out of work so late. I was wondering what this actually means and what it deals with in the rear-end. I know somewhat that it means the driveshaft is able to move in the opposite turning direction, but what does this mean for the rear-end? __________________ 1989 Mustang 5.0 Conversion, Full Saleen ground effects and spoiler, '94 saleen decal set, '93 Saleen Seats, Black interior from a '93, Steeda quadrant, smog pump delete, a/c delete, Steeda Tri-Ax shifter, '97 rear differential, aluminum driveshaft, 5 lug conversion, '97 rear disc brakes, southside upper and lower control arms, '99 GT Anniversary wheels, flowtech longtubes, flowtech offroad H-pipe, saleen lowering springs, kyb shocks, caster/camber plates

10-29-2003, 06:44 PM	#2
andy669 Registered Member Join Date: Jan 2001 Location: Moline Il Posts: 901	Chances are the oil leak is from the rear main. Backlash is the measured distance the ring gear will rotate without the moving the pinion. Basically its the distance between teeth of the ring and pinion. Normal is around .018". If all the tech is doing is rotation the driveshaft and saying theres 1/4 inch of backlash, hes an idiot. Being able to rotate the driveshaft 1/4 inch is normal. Was the rearend making alot of noise? Andy __________________ 88 coupe 91 LX NMRA Pure Street 5120

10-30-2003, 02:39 PM	#3
302 LX Eric or '331 LX Eric' Join Date: Jan 1999 Location: Columbus, Ohio Posts: 2,142	Andy's right on. Just to add a little bit to the above...you want to make sure that the backlash is set w/in tolerance or else you'll get excessive gear wine and wear - or possible breakage. It's an easy thing to measure with a dial gauge mounted to a magnetic stand: just place the dial gauge on perpendicular to one of the teeth on the ring gear and measure how much movement occurs (back and forth) while the pinion is stationary. Adding or removing shims from one side of the carrier to the other and vice-verse will either increase / decrease the amount of backlash. But, as stated above, turning the driveshaft a 1/4 inch either way is normal....I wouldn't trust this 'mechanic'. E __________________ 1991 5.0 LX Coupe - 40,750 miles 331 cu. in. / Tremec 3550 / BFG Drag Radials 12.22 @ 114.31 mph - w/1.89 60'

10-30-2003, 06:06 PM	#4
Rosco Registered Member Join Date: Mar 2002 Location: Vestal, NY Posts: 307	Thing about the oil leak..I really don't think it's the rear main. That was replaced less then 15k ago. Yeah, the mechanic said i should be able to hear noise coming from the rear-end if there was alot of backlash, I haven't heard a thing. I guess i'll just have a shop look at the axle when they install my gears. Thanks alot guys __________________ 1989 Mustang 5.0 Conversion, Full Saleen ground effects and spoiler, '94 saleen decal set, '93 Saleen Seats, Black interior from a '93, Steeda quadrant, smog pump delete, a/c delete, Steeda Tri-Ax shifter, '97 rear differential, aluminum driveshaft, 5 lug conversion, '97 rear disc brakes, southside upper and lower control arms, '99 GT Anniversary wheels, flowtech longtubes, flowtech offroad H-pipe, saleen lowering springs, kyb shocks, caster/camber plates

10-30-2003, 10:04 PM	#5
andy669 Registered Member Join Date: Jan 2001 Location: Moline Il Posts: 901	Eric did a better job of describing it. If you are putting new gears in they will check the backlash when they install them. I'm guessing everything is normal now. As for the oil leak, its not going to be easy either way. Replacing the pan gasket isnt easy. Personally, I'd rather pull the trans and change the rear main again, then replace the pan gasket. Andy __________________ 88 coupe 91 LX NMRA Pure Street 5120

11-03-2003, 06:03 PM	#6
Rosco Registered Member Join Date: Mar 2002 Location: Vestal, NY Posts: 307	Dropping the pan shouldn't be that bad of a problem, but i do have to replace the gasket, and both front and rear seals on the oil pan. Is there anything i should look into changing as well? __________________ 1989 Mustang 5.0 Conversion, Full Saleen ground effects and spoiler, '94 saleen decal set, '93 Saleen Seats, Black interior from a '93, Steeda quadrant, smog pump delete, a/c delete, Steeda Tri-Ax shifter, '97 rear differential, aluminum driveshaft, 5 lug conversion, '97 rear disc brakes, southside upper and lower control arms, '99 GT Anniversary wheels, flowtech longtubes, flowtech offroad H-pipe, saleen lowering springs, kyb shocks, caster/camber plates

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