Porsche Enthusiasts Club Forum

The 944 has been doing the daily's work recently as my gf has needed the Mazda. It's been spot on until today!

Pulling into the work carpark after a 20min stretch of dual carriageway it was fine until I selected reverse to swing into a space. Car felt normal pulling away but there was a loud grinding noise from the gear box direction while the car was moving. I went forward again in first and the grinding noise was there again. Rolled back into the space and left it there.

I think I have a basic understanding of the gearbox innards, but I've never had reason to play with one, so I'll try to use lunchtime for some diagnostics - primarily I think to see if the noise is limited to 1st and reverse - as they share a shaft would that point to bearings on that shaft having gone?

Am I likely to cause more damage (are there likely to be bits of metal floating around?) by doing that test?

Are there other things that I can check in a car park with no jacks? Can borrow tools from work, but I'm not dressed to be doing too much crawling under a car.

I'm presuming a ride home in a recovery truck today... First time in three years ownership, not too bad I guess!

Well where to start! I've been forced to learn about gearboxes very quickly of late. I'd say it's a good shout it will happen with all gears, if it is indeed the gearbox. It may be a CV, would be best result, but somewhat unlikely. First thing is to check for gearbox oil. You should be able to feel it with your finger tip when the fill plug is out. I would then drop the gearbox oil and check for swarf. If it has happened suddenly it points to a rapid gearbox oil loss or something gave up inside the box. Could be anything and unlikely to be diagnosed until box out and opened unfortunately.

You could also have a stone stuck in between a pad and a disc at the back or you could have a bent or disintegrating brake back plate fouling on a disc, either of which would make a grinding sound in all gears, and be an even better result than a CV failure! If it does turn out to be the gearbox I would suggest getting a known good lux box to swap over would be by far the cheapest option. They are plentiful for around the £200 mark on ebay.

Stuart

Thanks Stuart, I've been reading your gearbox woes! Didn't have much to contribute though...

The CV's were clonking a while back, replaced them with 4 new GKN ones about a year ago so unlikely but I'll take a look. I had a quick glance under before I left the car and didn't see any evidence of oil, but it might all be on the A46 somewhere!

What struck me was how sudden it was. I had got lucky with traffic, got from the A46 to the car park in 3rd and higher, then the moment I moved in reverse it was very grindy.

the other option could be the clutch has fell to bits,

but to just stop and then select a gear and the noise is there points to something else other than gearbox, if it was a bearing failure it would have been noisy for a while.

I'd check the rear pads and discs, handbrake mech and your brake back plates as a first port of call.

I do happen to know of an early 2.5 lux box as it happens, its up in Scotland so postage would need paid but sure I could get it for you for a decent price if it turns out you need it.

Stuart

Clutch did occur to me, but the noise was definitely from behind me, and I could still select first and pull away as normal. No knocks or clunks, pulled off smoothly.

I'll feel really silly if this is just a stone caught in the dust shield or similar... I've had that before though and this sounded more like a bearing. Hopefully I'll know more after lunch

Thanks guys!

I may just be feeling a bit silly... No evidence of anything rubbing, car drove fine, although more whine from the gearbox than I remember - probably just because I was listening specifically to it.

I'll drive home and see if there's anything different when it's warm. This has given me the little kick to finally do a gearbox oil change though

Looks like a slight overreaction on my part

Thanks for the help!

First and reverse can tend to be a bit grindy and occasionally difficult to select, especially reverse, if you don't quite get it in there fully normally caused by wear in either of the gear selector linkages.

Changing the oil in the transaxle is a pretty simple job, but you will need a 17mm hex key to get the plugs out. Well worth doing, especially if you have no record of it having been done.

sshhhhh.....I have first dibs on that box, for when I blow the one in my track car

When changing the gearbox oil the plugs can be incredibly tight, and undo the filler before the drain, if you drain it out then can’t undo the filler you will be in a bit of a pickle

Ha ha! Where are you in Scotland?

Two more commutes down... When everything is up to temperature there is a crunch sound when pulling off in first. Clutch down and gear selects fine, clutch up to bite point and a brief ~1s grinding noise as force goes through the drivetrain to the wheels, then pulls away as normal.

It still sounds like it's coming from the rear, but could well be the clutch. I tried pulling away in second as a test, riding the clutch a little and there were no suspect noises, just pulled away smoothly.



I've just re-pinned and re-bushed the front linkage which has removed all of the fore/aft play but there is still significant side to side play from the rear selector... Need to replace that but I look at the prices people charge for them and my head goes "I'm sure I could make one..." Would be an interesting exercise before giving in and buying one at least

I've done a few gearbox oil changes on other cars and have a set of large plug hex keys, just never got round to the 944. Shifting has always felt impressively smooth on it as is. The 'specialist' I bought the car from claimed that they'd changed it, but I saw no witness marks from tools on the plugs, or oil on the casing so I suspect it's not been done in a long time.



Absolutely, the less pickling the better

Now to find a decent GL4 oil... Despite all the high praise (and expense) Swepco 201 is still GL5 so should probably be avoided? (Edit: just checked clarkes and it say's GL5 is the recommended oil spec from Porsche. More reading required apparently!)

At risk of going slightly off topic... you're running a lux box with the V8? I was under the impression that they weren't strong enough and were generally swapped out for tubo or S2 boxes?

All of the 016 boxes (I think all 944's use an 016 variant) are fairly tough and with decent oil change intervals and use of decent oil they should be good for lots of years and abuse. The only difference to an S2 box is more aggressive gearing which gives better acceleration traded off with lower top speed. So some racers go this road. The only box which is "tougher" is the AOR box, or turbo s box, which has shot peened shafts and hardened 1st and 2nd gears. It also benefits from an external oil cooler and an LSD which are both advantageous for hard driving. The LSD can be swapped in to any 016 box but you need a specific casing to use the oil cooler. Its also worth noting the square dash and oval dash use different mounts and different speedo drives so it's not a simple task to swap a later box in to an early car.

Get a decent 75/90 synthetic oil.

Stuart

I think this whole GL4 vs GL5 topic is a bit of a red herring. I did quite a lot of research before changing the oil in mine and I came to the conclusion that some of the older cars had handbooks calling for GL4 because that was the current state of the art. The Porsche workshop manual calls for GL5 from memory.

I believe that if you use the better synthetic oils they are suitable for both GL4 and GL5 applications (rather than simply being backwards compatible) and they don't tend to smell of sulphur which I understand to be the telltale of GL5. I went that route (I think I used some expensive Motul stuff from Opie) and it seems to be fine. Can't say I noticed a massive improvement but the shift was pretty good to start with.

I hope you get the grinding noise sorted out without too much expense.