Small Crunch From 3rd To 4th

[nsta]

Hey guys i recenetly done an auto to manual conversion in an r33 with a box that had done 51000kms(rb25det), problem is when shifting from 3rd to fourth in high rev range, theres a slight crunch, and no its not my driving hahaha. Are my synchros gone?and should i take it easy cause its doing that?

[KLR33]

what oil and additives did u use ?

r u sure the box only had 51 thou on it ?

sounds like synchros or old oil but if u just put it in may be wrong oil.

Edited October 7, 2007 by KLR33

[nsta]

i used castrol vmx80 5spd transmission oil - 4 litres of it to be exact...

[benm]

Common problem in the RB boxes, some redline lightweight shockproof can mask the problem but it's just a wearing gearbox. My 89 gtr has new bearings and syncro's and doesn't crunch at all.

[nsta]

how much does it cost you for new bearings/synchros?

[benm]

Not much less than buying a new complete gearbox from japan.

[MotoMan]

new gearbox $2800 +fitting

bearings and all 5 synchros including labour $1500-1800

not a whole lot cheaper

Edited October 7, 2007 by MotoMan

[PT]

yeah 3rd to 4th seems weakest synchro in the RB25 (well it appears that way from the last 2 RB25 boxes I've had)

yes you should take it easy, shift slower so your actually rev matching or even though it can be a pain clutch IN shift to neutral clutch OUT then clutch IN again and select 4th this was all I could do on my old box as the synchro was totally rooted, don't keep grinding or forcing it in you'll just wear your box out quicker. If the other gears are good and no bad bearing noises I'd just put up with it, the synchro's themselves aren't expensive it's the labour to pull the box off car/pull box apart etc that costs the most

[nsta]

cheers mate, whats the life expectancy of a fully rebuilt manual transmission?ikm just thinking of doing this once my box starts to get old, it works out cheaper in the end, and at least that way you know youve got a new box recon. and not taking the risk buying another 2nd hand one that may be rooted!

[benm]

Except that you could get about 5 second hand boxes for the price of a new 1.

[nsta]

thanks, exactly how cheap can i get a new rb25det box for?

[MotoMan]

thanks, exactly how cheap can i get a new rb25det box for?

Brand spanker is around $3K plus fitting...

2nd hand around $1500...

Fix your own $1500-2000 (bearings synchros) including clutch

[charlie25T]

i used castrol vmx80 5spd transmission oil - 4 litres of it to be exact...

you used 4 ltrs.....................

i use royal purple and only used 3ltrs

[nsta]

yeah used 4 litres, i know of alot of people who have been using 4 or close to 4 litres, is this sound right?

[MotoMan]

yeah used 4 litres, i know of alot of people who have been using 4 or close to 4 litres, is this sound right?

yer i put around 3.5-3.8 litres in mine..