Shark Attack

after the big frame issue, I am now having the tranny done ( 5 speed, mine needs syncros)... The guy that sold me the car is doing the work as a favor to say, Hey i f'd up when i sold you the car.... all i have to do is buy parts. We have desided to rebuild one he has then just exchange the two. Now, Not knowing this tranny that we are going to rebuild. I assume new sycros on all gears.. all new bearings including the throwe out....the clutch feels good at this point. the TT has no issues that i can feel. what else should i look for or what can you rip apart about my above plan???

any advice would be great....

PS I plan on supercharging or going turbo in a year or so, if that matters.....

Andre Hedrick

SA,

Been there done that, and now headed to FOURTH tranny! I have paid lots of "stupid tax", and the finally tranny is a G28/13 w/ LSD. Don't rebuild anything less than a G28/10, the syncros that are not BW so not last long. I hated my 05 rebuild (cost $1400+), base was 178K miles. It is forsale cheap $350.

You need an extra $3K to find the desired tranny.

You asked for input, it worth what you have paid for it.

Cheers,

Shark Attack

Ya know what that reminds me.. the tranny in this car is thought to be an LSD..... I should rebuild that one huh? how can i check for sure if it is or is not?

mark kibort

with the car in neutral, jack up the rear and spin one wheel, both should spin the same direction for LSD

MK

WallyP

"We have desided to rebuild one he has then just exchange the two. Now, Not knowing this tranny that we are going to rebuild. I assume new sycros on all gears.. all new bearings including the throwe out..."

A bit of research might change the approach a bit. As an example, the input bearing alone is $485.

Buying a good used box might be better.

You can move the LSD from one box to the other.

Shark Attack

You guys are great, I dont care what my wife says! Ill check for the LSD tonight. can i lift the whole rear on the "pumpkin" like an old chev.

You all make great points. the car is a 79 so it could have anything in it.... is there any numbers to check exactly what it is? if so where are they?? Let me guess you have to remove the tranny to see the number on the top, right?

is an early LSD compatible with an 85 or later tranny? where might i find a later tranny?

Jim bailey - 928 International

When you hear grinding crunching when you shift everyone calls out "Worn Syncros" which is TRUE but BIG BUT the noise is NOT from the syncros but is from the gears dog teeth and sliders. The parts are eating up each other every time it grinds. One recent trans rebuild excluding labor it needed about $2,000 in PARTS using some good used parts if new it would have been over $3,700 in parts. That trans became just a pile of parts only some of which are any good. The Porsche design syncronizer transmission is a pretty good road race box but a rather poor drag race box. The later 1985> Borg Warner style box is more tolerant of the abuse of drag racing. All the 911s used Porsche syncros until 1988 !

John V

I'm in the devil you know camp. I know whats bad in my box... buying used, you just don't know and even warrantied, the labor it takes to get it on and then off if there's a problem is substantial. Then there's shipping to deal with in many cases. Not an easy decision in my book.

Would I like BW synchros, yes. But I like my early box's final drive ratio better than the newer box's. I thought guys were having good luck rebuilding the old box's for street applications... racing is a whole other story. Any more info would be appreciated.

BC

I have two 78 transmissions. One is in the 78 and one is in the cabinet. I bought another one so if I screw one up, I can pop the other in. Cheaper it seems.

I do need to rebuild both. It will be a good learning experience.

sublimate

I think the 928's front engine/rear tranny has the biggest effect on the life of our syncros. Our syncros have a lot more mass to slow down and speed up during shifts - the normal clutch and input shaft plus the whole TT shaft - while the 911 syncros have a lot less to contend with.

If only they'd put the clutch and the rear...

Jim bailey - 928 International

The driveshaft weighs 12 lbs BUT is ONLY 1 inch in diameter so it has little flywheel effect.

Shark Attack

I was told today, by a porsche wrench that the early trannies are very week and even after i rebuild, if i miss one gear i may ruin the sycros and be back in the same spot im in now.... that doesnt sound right.. is it? cost is always a factor.. but to have anything done right costs money.... yes 3500 is a bit more than i wish to go.. but if my tran gears are working now..... why would they not work after a rebuild? that is if i rebuild the one i have.... it doesnt pop out of gear... their is not a lot of grinding when you know their is a problem... you just have to drive it a little easier... so i do not think i am makingh things worse right now..... the trans just isnt right.. and i cant stand when something is not "right"..... it has to be fixed or gotten rid of..... now that brings me to my wife... oops thats another story

svp928

If it's any consolation, I have 9 yrs and quite a few track days on a rebuilt G28-05 with LSD. Got it from 928 Int'l, and was built by the shop Mark uses in SoCal. Still shifts fine, and I haven't been very nice to it. You get sort of carried away by the heat of the moment on the track... I even admit to missing a shift once in a while...the instructor distracted me, right... Trans now has about 40k on it, no issues. My car has 285's on the rear, so its fairly well connected back there. I DO keep on top of the clutch adjustment for the 2 discs, and I think this has a lot do with life of the old synchro's.
So, I wouldn't be too afraid of your old style trans. The gears themselves are really not any weaker than the later ones, they just have different cones and dogs for the BW style synchro rings.
Just my .02...

Steve

BC

I may simply do a single disk clutch when I get the 78 put together. I have a 78 flywheel though, ready with the 36-1 wheel I need for megasquirt.

Rick Carter

You can get a rebuilt trans from 928 Int. for $2500 plus core exchange. Other vendors may have similar deals.