Crunch in 4th gear
 

My bugeye is on 92k miles, I put it in a recommended garage for a full service last week, everything done gbox oil, diffs all filters etc

Last few days I have noticed when I select 4th gear at 3k rpm or over im getting a crunch when gear engages

A quick search shows possible problem, either gear box oil level, type of oil used or syncro issue

The car is due back at the same garage for exhaust work tomorrow, do you think the crunch is related to the service? Had the car 6 months and only started after the service

I have the same issue on my 03 sti, had 60k service that includes gear box oil and still the same. Had a clutch done after as that gave up the ghost but was told to keep running the box with the cruntch if i could put up with it as would cost £1200+ to rebuild the box on top of the clutch.

Mine only cruntchs on boost really but is 100% drivable, syncros are prone to this i was told.

Wouldnt it be cheaper getting a used box put in?

Whats the spec of your car? WRX or STI?

02 wrx ppp wagon, had service 2 weeks ago and this crunch started a week after it, annoying as hell as scared to boost from 3rd into 4th, no fun at all

what gearbox oil did they use? my 93wrx crunched into 2nd with the wrong oil. switched back to castrol and its fine again.

I dont know will talk to them tomorrow about it, hope an oil change will sort it

Change the box oil again and use COMMA SX 75/90 GL4. make sure its this exact oil dont use the GL5 spec oils as this is what causes subaru synchro probs. It fixed my 6 speed 5th crunching issues. Its not expensive oil either.

incorrect oil used.
 

Subaru recommend only to use Subaru extra s oil in their transmissions. Specially blended oil which is synchro friendly.
Castrol syntrax now called castrol universal is o.k or Comma SX 75/90 GL4 .
GL5 transmission OILS ARE THE ROOT OF THE PROBLEM. They have double the extreme pressure additives of Gl4 oils and cause synchro problems.

Castrol universal is the stuff you want, I put comma in and it made the problem worse. put the universal in and its like new again.

comma sx75/90 comes in GL4 and GL5 variants. Look at the label carefully when purchasing as they all look the same. Comma sx 75/90 GL4 ONLY is the direct equivalent of castrol universal. You may have used the GL5 variant in as I did originally causing the problem. The GL4 cured it.

nope It was gl4. still got the bottles in the garage.

If one dont work try the other i suppose. One should work...

I tried the cheap option first ha ha 20 something quid. ended up spending twice. the Castrol is 40+

I'm getting crunching in my bug eye in 5th over 3k revs. I was told it's more than likely a syncro issue and best thing to do is change the box for a decent condition used one. Now I've read this its got to be worth replacing the oil with castrol universal gl4 first to see if it fixes the issue. If not ill be looking for another box.....

is yours a 6 speed or 5 speed. Remember the GL4 SPEC is the critical factor.

The garage have told me they used lucas 75/90

I am looking at castrol universal and some other oils mentioned here and most of them say gl4/gl5 on the bottle such as here http://www.halfords.com/motoring/eng...rsal-75w-90-1l

Can someone link me to the right castrol universal I should try

The castrol universal is supposed to cover both .
I used Comma SX 75/90 GL 4. Its cheaper than castrol universal and comes as GL4 specific. Its the castrol equivalent. Cost me £22 for 4 litres in my 6 speed box. Stopped my 5th crunching at high rev upshift.

Mines a 5 speed. I think I'll go straight for the universal as dj said he tried both and universal stopped his crunching. Mines only just started doing it so hopefully I will catch it before it does any long term damage.

Can anyone confirm if this is the right stuff and how many litres to buy? Thanks
http://www.opieoils.co.uk/p-744-cast...universal.aspx

Is it the part synthetic castrol universal people would recommend or the fully synthetic universal plus worth using like here.....
http://www.opieoils.co.uk/p-77373-ca...-diff-oil.aspx

Did it sort the clunking in yours Miztera? Ive gone for the castrol universal 75-90 but still clunking in 5th. Every other gear is fine. Looking at either getting the box rebuilt or a used replacement fitted along with new clutch and flywheel.

Ive not tried to sort mine yet, too busy with other things. But the funny thing is mine only starts it crunching once the gearbox has heated up, it wont do it when still cool/cold.

Been a long time, but heres an update.

The garage servicing the car who are subaru specialists had used millers gbox oil and thats when the crunch into 4th gear started. I limped the car around for a few months avoiding high rev upshifts into 4th.

I got them to change the the gbox oil for castrol universal when the car was in for other work recently and guess what.... crunch is gone.

The crunch would not happen when the gearbox was cold, it would only happen once the gearbox had heated up, then everytime I upshifted into 4th above 3k revs it would crunch in.

Castrol Universal 75w-90 semi-synthetic gear oil (formerly Castrol Syntrax universal) from opie oils.

So pleased

Alas GL4 didn't sort my 110k mile 6 speed out: in fact it is worse than with Millers synthetic.

Worth a try ... but looks like box out time :cry:

Try the castrol universal before you take the box out, millers caused my crunch as the syncro's did not like it, castrol uni sorted it out instantly

Here the link http://www.opieoils.co.uk/p-744-cast...universal.aspx

well worth a try.. API quoted me £1800 for a six speed synchro repair. Thats with box already out...
These 6 speeds may not strip the gears but the synchros are Sh*t..
you can't win...

Alas that is the oil I tried as I had seen this thread when I was experiencing the issue ...

Now have Millers 75/140 in for a while and it has made a significant difference with it much, much better now with just a little stiffness going down into second when cold .. otherwise fine.