G50 trans newbie

Al Cody · 03-10-2010, 10:28 AM

I recently bought an 87 Carrera with the G50 trans. Most of my interest in that year was for the G50, as it is very well spoken of. However, I have to say I am not overly impressed with it so far.
Once its warmed up it ain't bad, but cold yikes.

Cold it is a bear to shift first to second, especially.
Any hints on how to get smoothly through the first mile or so until it warms up? It feels like I am forcing it into second, which is not at all pleasing. Warm it shifts fine as long as I am at least moderately sensitive to the shifting. Down shifts actually go better than upshifts.

What gear oil is best with this box, (not a limited slip). 3 liters like the 915?
Thanks.

porschenut · 03-10-2010, 10:37 AM

This is normal behavior for the G50 with Borg-Warner synchromesh. Nothing you can do but be gentle until it gets warm.

If you think that's bad, try driving a Ferrari 308 when it's cold.

detroiter · 03-10-2010, 10:48 AM

Here's the latest discussion:

http://forums.pelicanparts.com/porsche-911-technical-forum/524583-swepco-transmission-fluid-quistion.html

Happy reading! :>

Randy

flatsixjunky · flatsixjunky's Garage

This is the opinion of a well respected member of the forum, post #20 on the thread detroiter linked.

Take care.

Al Cody · 03-10-2010, 01:50 PM

thanks, I figured Swepco would be the way to go. And I'll read the string.
Seems like the hotter it get the better it shifts.
I'd love try a cold 308

flatsixjunky · flatsixjunky's Garage

The link to the thread posted by detroiter say's that swepco is not the best option for the G-50, it's the best option for the 915 tranny. Read the thread, there are several good options posted for the G-50.

Take care.

NewfieMZ3 · NewfieMZ3's Garage

Swepco for the 915, full synthetic for the G50. Royal Purple maybe?

McLovin · 03-10-2010, 02:10 PM

Quote:

Originally Posted by Al Cody

thanks, I figured Swepco would be the way to go. And I'll read the string.
Seems like the hotter it get the better it shifts.
I'd love try a cold 308

swepco is not the way to go.

your G50 almost certainly has the wrong fluid in it, which is causing the problem.

Put a synthetic in it. I've tried a bunch of them over the years, I like Mobil 1 Delvac 70/90 the best.

Al Cody · 03-10-2010, 02:11 PM

okay, read the thread...maybe not swepco. full synthetic kendal or redline glad it isn't a worn out transmission, i was worried cheers.

McLovin · 03-10-2010, 02:13 PM

Here's a link to the Mobil 1.

Mobil Delvac Synthetic Gear Oil 75W-90, 80W-140

McLovin · 03-10-2010, 02:16 PM

BTW, the mid 80s Ferraris are difficult to deal with as far as trans lube, because the lube is shared with the trans and with the limited slip differential. One lube needs to handle both, and they have somewhat different needs.

88-diamondblue · 08:10 PM

Use the Mobil Delvac 1 for non LSD and Mobil Delvac 1 LS for trans with limited slip.
I have used the Mobil 1 from the local flaps and the Delvac 1 has been better IMHO. Porsche Racing factory fill is Delvac 1

KTL · 03-10-2010, 06:54 PM

A very balky shift like that is more than just fluid. My transmission suffers from that same inital 1-2 shift problem when cold. Only the first 1-2 shift is a a real bugger. I double clutch it, and each shift afterward can be normal-clutched and they each get better as teh trans warms.

I certainly agree that synthetic fluid in the G50 is an improvement, but it's not a cure-all. I actually have used local auto parts store off the shelf Valvoline non-synthetic 80W90 gear oil in my trans with good results. I switched to 80W140 for very hot days at the track and it performed better than Mobil 1 Delvac/SHC- less crunching of gears on quick upshifts.

kidrock · 03-10-2010, 08:00 PM

You may still have some "stiffness" in 1-2 with Delvac or other full synthetic, while cold. I followed earlier recommendations of "double clutching" with good success. Also, I've noticed a good difference with allowing a slight stall into neutral while transitioning between 1-2.

In other words, while cold, you will need to pause a bit between those gears...until warm.

Por_sha911 · Por_sha911's Garage

Your G50 requires a full synthetic 75/90.
I figured that a notchy 1-2 shift in my LSD when cold isn't the worst thing since I want to let it warm up first since the oil needs to warm up before getting it above 4K anyway.
I've been told that you can mix your lube: 1 qt of non LSD in with the rest for LSD (same brand synthetic 75/90). Has anyone tried this?

KTL · 03-11-2010, 01:33 PM

The G50 doesn't REQUIRE a full syn. lube. However it does LIKE some of them. The specs. for the car, according to the tech specs book issued by Porsche simply states that 75W90 GL-5 lubricant be used.

And yes you can mix lubricants. A Redline Oil representative, who incidentally had a 993 at the time, suggested I use their 75W90 oil with a blend of 1 qt. Redline Lightweight Gear Oil

SpeedracerIndy · 03-12-2010, 09:48 AM

Quote:

Originally Posted by porschenut

This is normal behavior for the G50 with Borg-Warner synchromesh. Nothing you can do but be gentle until it gets warm.

If you think that's bad, try driving a Ferrari 308 when it's cold.

Really? I've driven several G50's, and never noticed them significantly harder to shift when cold. Maybe a tad bit stiffer until warmed up, but not like the original poster described. My dad has an 88 with 90k on it, and it shifts nice and smooth right out of the garage on a cold morning.

I think the OP's trans has the wrong fluid in it. I wouldn't be surprised if green/blue sweppco comes out when he changes the fluid. People praise that stuff so much here that a lot of people assume it's the right fluid for EVERY 911.

dshepp806 · dshepp806's Garage

Mine's a tad bit tough on REALLY COLD mornings,..I'm just careful with it...otherwise she gets up to temp and is smooth as butter...

Mobile One Delvac 75W90 (GL-5) for my G50.

On a sidenote,..I don't recall "who" but someone posted (long ago) [[[may have been Grady?]]]]] something I do always, now:

When ready to engage first (on those cold mornings), I will first put the tranny in third,..then shift to first...it's smoother that way,....IIRC, something to do with "setting up the syncros" (whatever the hey that means)..after getting through second then on to third gear, (cold mornings,....) I stay there,..around 3K RPMS until I start to build some oil temp.....I'm VERY careful during this initial drive "stage" (cold)...Hell,..I won't even let my car see 4K RPMs until she's TOTALLY warmed up...

By then , the G50 is the least of my worries.....

Fluid selection can DRASTICALLY impact performance.

Best,

Doyle

dshepp806 · dshepp806's Garage

also,..double-clutch that second gear shift (when cold)....

Doyle