rb20det third gear crunch.

[mek]

Crunches third at high RPM all other gears are fine and third is also fine at low revs.

What could be the problem?

Broken mount?

Missalignment?

Shagged gearbox?

This is an RB20 into Sil by the way.

Thanks!

[Joe]

Sounds like a synchro..

Best thing to do is try some Redline lightweight shockproof. In WRXs, this can cure crunchy synchros.

If it doesnt work, then your synchro will need replacing to stop the crunching.

[mek]

Bulk $$$ to replace a synchro? Sorry...im a gearbox n00b

[Joe]

Usually its the labour thats pricey....remove, disassemble, replace synchro, reassemble, refit.

If your box is pulled apart, you may find other bits that are also worn/damaged, so that becomes a further expense.

For the dollars, its probably worth getting another 2nd hand box and putting that in.

Like I said before, try the Redline lightweight shockproof gear oil first and see how that goes :)

[mek]

Thanks for that. i will give the redline stuff a go.

i did some digging also and looks like it would be cheaper to just get a 2nd hand box and not bother fixing the stuffed one.

Thanks again.

[tuyen]

experiencing same problem with mine man. Got some motul rally spec oil in it though.. didnt help.. yeh guess gotta live with it til got enough dough for a better box...

[Iandawsonwa]

if you going for a 2nd hand box get an R33 one

[SkyviaPete]

dont mean to hijack, but is 33 box straight bolt on on a 20?
do u have to change the bracket for a silvia? mine doesnt enjoy flat changing much anymore