Gearbox question

[Elsaetka]

Hi,  would appreciate some feedback on the following re the gearbox in my 1.9 DG, 1990,  standard 5 speed box.

I have started to get a gear crunch when changing from 1st to second, (nothing else), i can avoid it by slowly changing into 2nd when the van has just started moving, i.e not holding 1st until the higher end of its range. 

It never used to do this although it did start of being a bit tight to select 2nd, had to push it a little compare to other gears. Under normal circumstances the van does very few miles per year so no problem to me.

One important factor is that the problems don't show when it's warmed up, which leads me to a point i'm coming to.

Problem is as well that due to my daily drive car being repaired at the moment I am using the T3 regularly, so not the best for a daily commute given it is 30 years old

About 15 years ago the box was refurbished by a T3 gearbox specialist who was by far the most recommended on the forum at the time, they were very good.  When I collected the box the guy said he always advised the use of the heavier grade (thicker) gearbox oil they had filled it with.

I absolutely went with his recommendation however I think the problems I am experiencing are made worse by the thick oil. I have a feeling if I put a thinner grade in, the problem might go, but of course I don't want to do anything to damage the box.  It crossed my mind about an additive I may have seen years ago, however again, would'nt do anything that could cause damage.

E D I T: Just realised after writing, that there is only one grade of oil recommended for the box anyway, the box currently has the correct grade as it was filled when the box was refitted by a VW dealer.

Thanks in advance for any advice.

 

[Aidan]

all our boxes suffer a little with baulking on the first shift of the day from 1st to 2nd and even 2nd to 3rd on the 5 speed because those lower change gears are on the lower (pinion) shaft and sat in the cold oil; when changing gear the synchroniser slider starts to move and the catch keys push the synchro ring into the cone of the gear to move the oil out of the way and grab the gear to slow it down and effectively line it up so the slider and gear's dog teeth engage in a tidy fashion; the faster you try to change gear the more you'll find it baulks and the leading edges of the dog teeth bang into each other and are blunted making the shift worse etc.. so slow gentle precise shifts are required initially, once the cold oil has been sprayed around the box by the spinning gears and started to warm then the problem diminishes.
VW tried to reduce the effect by lowering the volume of oil in the petrol boxes to 3.5 litres, but this also reduces the oil in the differential area and may lead to higher wear there; ultimately VW developed the oiling plates that were fitted to the SA vans to improve oiling to the crown and pinion and top two gears which also reduce oil temps thus reducing carbonisation (and thus helping to keep lubricity) of the oil.
I recommend a fully synthetic 75w/90 oil, 4 litres for all 2wd boxes. The 75w means it is less gloopy when cold so helping with those first gear changes, but you still get the 90w protection when hot. Smith and Allan is readily available on Ebay and direct by phone, UK blend and packaging and good value for money, dual spec GL4 and GL5.
Change the oil every 3 years or 20k whichever comes first. Only by changing the oil do you see the drain plug magnet and gauge the wear between oil changes and get the box rebuilt before the wear is excessive. Oil is cheap, rebuilds aren't and will only get more expensive as parts availability (both new and good used) reduces and cost of new parts increases going forward. Brexit will probably force a cost increase of between 5% and 20% on parts from Europe, and we have already seen some parts increase in price by more than this, this year. Availability of good used boxes now is pretty minimal, long gone are the days of £50 used boxes.
When VW said sealed for life they meant 10 years, 100k miles, throw it away and buy a T4, they didn't mean keep it on the road for 30+ years. I still see boxes in 'original' condition and the wear due to the oil no longer lubricating makes me weep, if only the oil had been regularly changed the box would still be great as it has clearly been driven with mechanical sympathy.
When there is wear in the main bearings then the shafts are able to move back and fro and that will have an effect on the gear shift, 5 speeds that pop out of 2nd gear on the overrun generally have a very worn pinion bearing and consequential wear on the face of 1st gear and 1st reverse synchro hub which leads to 1st bearing failure and some very expensive damage; it usually shows up as sludgy build up of fines on stem of drain plug magnet in addition to any spikey head.

 

[Elsaetka]

Hi Aidan,
Thank you for taking the time to give such a comprehensive reply,  I found your explanation not only extremely helpful, but also very reassuring, because fortunately I flagged this almost as soon as the fault manifested itself and thankfully as you say, I have been very careful with the changes.

I just arrived home from a journey of a few miles and it was absolutely fine as soon as the oil had some heat in it.

I was hoping an oil / viscosity change may be the answer and you have confirmed that, I really do feel it will make a difference.

I ordered the oil straight away from the supplier you recommend and will get that changed as soon as I have my car back. I can do it myself, however given the temperatures / weather I have a former colleague who was a VW Commercial Master Tech who now has his own business near me, so either way the job will be done properly.

I will update this post in a few days when the work is done.

My thanks again.