Engine drop question

maxhofer · 06-09-2011, 03:38 PM

I'm about to drop my engine for a rebuild.

I'm planning on dropping the engine along with the transmission.

My question is: where is the center of gravity for the engine+tranny assembly?

I want to make sure I place the jack in the correct spot.

The car is a 1985 Turbo-Look.

shrtshck · 06-09-2011, 05:16 PM

Working from memory, based on dropping my 3.2 with G50 the CG falls be on the engine side of the flywheel.
I used my main floor jack under the engine and a smaller floor jack under the trans crossmember to position the transmission. The concern with using the center of gravity to balance the engine transmission on a single point is it will be unstable. Any bump or push will knock it off balance and it dump it.
Used a piece of plywood between the jack and the engine, in the center of the plywood I screwed on two small strips of wood spaced about 1/2 inch apart. I positioned the center seam of the crankcase in the small gap between the wood strips.

Best of luck with the drop, last fall was my first time. She is now back together and running stronger than ever.

Ken911 · 06-09-2011, 05:25 PM

i got that floor jack adapter they sell here it fits the Cg perfectly and is ajustable to get the angle right as it slides into the car.

billjam · billjam's Garage

I made up this adapter from plywood many years ago and it has done many engine drops on Carreras and 930s (same crankcase shape).
I screw it to the jack pad and it fits snuggly under the engine just ahead of the the balance point.
Looking at the second pic, the CoG is maybe 1/2" behind the centre of the jack pad for a 3.2 and 1" for a turbo (based on standard exhaust weights).

maxhofer · 06-10-2011, 06:16 AM

Shrtshck and Ken, thanks for your answers.

Bill: your adapter looks very nice and easy to build. I'll try to make my own.

Max.

Number1_dog · 06-10-2011, 07:42 AM

One thing you have to remember to do is tip the engine down and the trany up so you can slip the transmission shift shaft out of the car body. You do not want to get that shaft hung up in the car body with the weight of the engine and trany on the other end.
I used a Motorcycle lift with a wooden saddle to cradle the engine and a smaller jack under the transmission.

shrtshck · 06-12-2011, 03:29 PM

The motorcycle lift works well, I had picked up one on sale years ago, never trusted it to pick up the bike but is does a great job for Porsche engine removal. The broad surface area ensures the engine and transmission are stable, a floor jack under the transmission allows you to position the transmission as needed. Did the drop and reinstall (first time) single handed.
It does-not have enough lift to bring the engine up to the mounts in a single lift. What I did was lifted the engine to max height, started the trans mount bolts to stabilize the unit, braced under the engine, then dropped the lift and added some spacers under the lifting board.