G50 gearbox questions

[reub]

Hi,

I'm new here with a couple of G50 gearbox questions.

1.
I've got a 1988 G50 5 speed box installed in my car. The gearbox is making engine speed related noise. The noise is primarily heard when backing off the accelerator, making a groaning type noise (obviously hard to describe). If when backing off I push the clutch peadal the noise disappears, but pulling the foot off the clutch pedal the noise comes back.

Also if accelerating at slow speed without shifting down, say in third instead of shifting to second, then there is a slight noise heard as well.

Any ideas?

2.
Can someone please provide gearbox oil capacity and confirm the filling/draining procedure (even if there is an internet link to this info).

I appreciate assistance with the above questions. Cheers.

[MConn]

The bentley service book calls for 3.6 quarts of lube.
There's a drain plug for the trans at the bottom, the fill plug is on the side - fill till oil runs out the side, I used a squeeze bottle, took a while.
Take this advise with a grain of salt because I'm a porsche newbie, but it kinda sounds like the throwout bearing.
My g50 improved when I switched to Swepco 201 oil.

[charleskieffner]

i'd second the throw-out bearing angle. i used mobil-1 and w/in a 100 miles a world of difference better shifting. good luck. dont even think about doing this on the ground the first time. my fill allen was so tight it took my buddies IR 1/2 impact to get it off! we tried with breaker bar then cheater bar.........then the IR impact finally got it! drain plug was pretty damn tight.........read that overtorqued by some MORON who hasnt a clue what a torque wrench is aside from some type of club apparatus! do it on a lift if possible and get long clear hose and hang bottle up above spring plate and let gravity do its thing. or do what one guy did on here from europe........get really long hose and duck tape bottle to roof and let the juices roll down hill!

[KFC911]

Welcome Reub! The conventional wisdom is that for the G50s, a synthetic tranny oil is best (Mobil 1, Redline, etc.) and the organic tranny oils (Swepco) is preferred for the earlier trannys. Before you drain, make sure that you can loosen the fill plug (on the side). They can be a bear to get loose if it's been a while and you don't want to drain it, then find you can't get the fill plug loose. When I fill, I just use a 1/4" tube attached to a funnel (positioned above the left rear wheel arch...the higher the better), and let gravity do it's thing. Good luck!

edited: Oops, Charles beat me to it...

[KFC911]

BTW, My fill plug is always a b**ch to get loose, even though I torque it properly. I've never had to use an impact wrench on it, but did require a breaker bar with a pipe extension.

[reub]

Thanks for the quick replies guys. Appreciated!

I honestly hope it's just the throwout bearing....fingers crossed.


Can you let me know the torque setting to tighten the filler and drain plugs to when putting them back in.

The transmission fluid currently in the box is a full synthetic, using Castrol Syntrax http://www.castrol.com/castrol/productdetailmin.do?categoryId=8290050&contentId=6007745 and will be refilled with the same....I think

[charleskieffner]

kc 911..........it sounds like you too have had the same fun as myself! read bentley and said this will be a snap.............and the next thing my tools are flying out of garage at warp speed and no creatures are safe on planet until job(mission) accomplished!!!! LOL have learned my lesson well.................1) read manual 2) drink a beer 3) read manual again 4) drink a few more beers 5) get on computer and ask stupid question on pelican 6) drink more beer and wait for response 7) drink more beer while laughing ass off reading responses 8) drink more beer and look back and forth from car to toolbox 9) go in house, jump girlfriend 10) wake up buy more beer and take car to buddies shop(with lift) and BRIBE him w/beer and tell him the exact way to do the job since you have read all the responses and then drink more beer and smile!......................repeat as long as you own the car! LOL!

[KFC911]

That's funny Charles! But...in my opinion, you're not using the proper tools....sometimes a job calls for beer, but if it's a real 'b**tch of a job', and you need a BFH to accomplish the task...that's when you grab for the tequila ! The first time I removed my fill plug, I too thought that King Kong must have installed it, but I've since found that it almost always requires a breaker bar w/ a pipe to remove. Reub, If no one else responds with the proper torque values, I'll look them up when I get home an post again this evening. I don't even want to speculate, but even though the torque values aren't that high, they can still be a bear to remove. Also another thing... if your car is filthy underneath, make sure you clean out the plugs good before you insert the hex bit. When clean, you can insert the hex wrench a fair amount and avoid stripping the plug or smashing your knuckles, etc. If you do smash your knuckles however, then reach for Charles' remedy....beer !!!

[MBEngineering]

HI just put in 'G50 gearbox noise' in the find box on this forum, loads of info to look through, you have two plugs to remove to change the oil, both with 10MM alankey size, drain under the diff, fill up the side of the box on your drivers side, fill to approx 3.5L of multigrade SAE75 W 90 trani'oil, API spec GL5.

regards mike

[charleskieffner]

kc 911 just got into office and had to laugh. btwn beer and tequila(TO-KILL-YA) we will have this guy having a cinco de mayo fiesta underneath the damn p-car! O-LAY! but back on track while you are planning the bentley 10 min G-50 oil change(yeah right!) try and plan your day around the job with digging up a hot water pressure washer and get some smart and final restaurant degreaser and some wd-40 both safe for alum/mag/steel/titanium etc and degrease the entire underneath of p-car from front to back. it WILL run cooler and you will be amazed the following hung over morning at how clean it is, and the value added bonus.............when you climb out from underneath your no longer a walking grease ball! was amazed at how much crap was underneath and how much cooler car ran. plus you will be able to identify all oil leaks and their source. and then that part of the bentley manual is opened! and the cycle continues! havent been able to find the BFH after last temper tantrum............its still out in the dez somewhere! the pelican underneath front hood throwing tools is a perfect visual!

[sushinav]

Eureka! Charles has finally shown me what I've been doing wrong all this time! Thanks for the help! Now I'll need your address so I can come over and do #9 (jump your girlfriend).

Reub, this is an easy job, but even for these, you should invite your nearest Pelican bro over to double check your work. Just post a "help needed in ______ town" here and see who lives near you. Pelicans are everywhere.

[charleskieffner]

suishi nav............too funny! it sounds like any of our next oil changes will be involving girls, beer, tequila and fellow pelicans! what more can you ask for???? well maybe more go-fast/stop quick parts! remember when you pay too much attention to the "mistress"...........girlfriends/wives get pissed off. so from now on include them, give them drinks, talk their clothes off..............and the next thing you'll know..........they will be doing the oil change for us naked! the power of persuasive speaking! it can only happen with a porsche! LOL!

[Hendog]

You'll also want to check and see if you have a Limited Slip Differential (LSD). This will determine what kind of tranny oil to use. In my case I don't have a LSD so I used Redline 75W90NS; the NS stands for No Slip. My G50 shifts great.

[KFC911]

Originally posted by reub
....Can you let me know the torque setting to tighten the filler and drain plugs to when putting them back in....

On the G50, both plugs should be torqued to 22 ft/lbs (per the Bentley Manual). As I posted earlier, even though I personally torque mine to the proper values, they can still be difficult to remove (and the first time I removed them after acquiring my car, they were a royal PITA, and required a breaker bar). Hope this helps....

[reub]

Thanks again for your assistance guys.

I've sucessfully done the fluid, just to make sure there is enough there. I drove the car yesterday. Can I ask that if the throwout bearing was gone would the gearbox make a chattering kind of noise at low revs? The noise is the same one as previously mentioned that has a kind of howl when backing off at high revs.

Just thought I'd post my further observations prior to pulling the engine out.

[charleskieffner]

hard to say what exactly it might be. since this is driving you nuts it needs to be addressed. i would look at the various options open to you as far as once your in their. stock OEM parts, or upgrades real carefully before doing anything. i have not had to replace clutch yet so i cant say whats best for your application. since i will be running mine at track im sure, actually make that positive i will have to have what is best and shell out wads of cash before i am happy. it just seems to work that way. but while in their i would do everything i could and then some to assure i dont have to go thru the ordeal for a very long time to come. the SACHS kit that pelican offers sounds pretty reasonable and its OEM im pretty sure. my stock clutch has never wimpered at track at all.........knock on wood.

[dean]

Originally posted by reub
Hi,

I'm new here with a couple of G50 gearbox questions.

Also if accelerating at slow speed without shifting down, say in third instead of shifting to second, then there is a slight noise heard as well.

Any ideas?



Cheers.

That is a normal noise from the G50. I got used to it quickly

[KFC911]

Originally posted by dean
That is a normal noise from the G50. I got used to it quickly

While not unusual (from what I read), my G50 makes no noise whatsoever....

[reub]

-

[reub]

Ok,
I've pulled the engine out....trans fluid every where.....
Looks to be leaking from the input shaft but also appears to be coming out of the breather under pressure as it's blown over my inlet and exhaust pipes.
Any ideas?
Cheers again