new gbox- noisey in 4th and 5th

[jamesmay]

Hi Kids...

I replaced a 752vb1aa box with a supposedly good 752vb4aa BUT it seems very noisey in 4th and 5th.

gutted...

does anyone know if its easy to remove the 4th and 5th bits from my other box (blown 2nd at autocross) and put into new box???

[kamineko]

easy? um well its possible. you would have to swap in all of 3rd as well

i wonder if its the gears or a bearing

[jamesmay]

unfortunately i don\'t know enough to be sure either way... there is a tiny amount of noise in third but very obvious in 4th and 5th. are bearing easy to change?

[kamineko]

what tools do you have access to? i know i need a bearing puller and shop press before even thinking about it

oh and the biggest f***off adj.spanner from supercheap

[kamineko]

un-educated guess : see the to rear bearings? the bottom rear one (driven shaft) is a thrust bearing. if damaged that would probably make noise under load in all gears

the top (input) shaft rear bearing does not see any thrust loading so *i expect* would be noisy from seeing load on the closest gears, 4th and 5th

again this is a guess. seems common for a shaft nut to come loose, causing weird things to happen as well

you do have that VB1AA box to learn on..

[Guest]

My 4th had a distinctive whine/hum in v3/4 sti box. Then granny shifting 3-4th coming out of 70km/h area it lunched itself completely. Pics in my garage thread. No idea if it was related to the lunching.

[jamesmay]

Ah, ha... my (very) narrow understanding of boxes... is that the input shaft has first and second gear on it? is it possible to replae the whole bottom shaft from my other gearbox?... silly questions i know, but i am completely green at all things mechanical.

[Guest]

Start with making sure they have the same ratios. I know with my v3/4 sti box it was the same ratios right through bar reverse as non sti v5/6.

[kamineko]

 jamesmay said:

Ah, ha... my (very) narrow understanding of boxes... is that the input shaft has first and second gear on it? is it possible to replae the whole bottom shaft from my other gearbox?... silly questions i know, but i am completely green at all things mechanical.

oh. well you have to learn somewhere. gearboxes are more of a show than a tell..

regarding the ratios,

TY752VB1AA 3.545 2.111 1.448 1.088 0.825 4.111

TY752VB4AA 3.454 2.062 1.448 1.088 0.825 4.111

yeah no problems. wait no you can\'t just swap in the other shaft. you would want to swap both input and driven gears 3/4/5 themselves so the cut is compatible

this is assuming the gears are damaged. i would assume if 4th and 5th are worn enough to make noise, the gearbox oil would be silver by now

[jamesmay]

oil is perfectly clean (only done maybe 30K\'s since install) i might just have to suck the sav and use my other spare box or con mum into yet another box purchase... anyone got a cheap box?

[Guest]

Plenty of cheap boxes around you just need to find them. STI\'s are easy to get to.

[Jesus]

Fuck ever trying to find a perfectly quiet box. Every single one ive bought has made some kinda noise. Current one whines a bit in 3rd but im just going to put up with it because everything else works.

And whoever was saying the input/main shaft bearing sees no thrust loading, yes it does. That metal plate that sandwiches between it and the transfer housing keeps it all in line.

[Jesus]

Hey Nick, is yours a 754 or 752 in that pic?

My one was supposedly a type R 754 and i can see a couple of minor casting differences. Wondering how different they really are inside.

[kamineko]

 jesus said:

is yours a 754 or 752 in that pic?

My one was supposedly a type R 754 and i can see a couple of minor casting differences. Wondering how different they really are inside.

mine is a TY752VB4CA

i was under the impression the TY75x was the shaft thickness which seems to increase over the years? something i\'ve only read though. would be good to measure up

[666SubSpeed]

752 = 4 bolt housing

754 = 8 bolt housing

There is info out there tell us exactly what each number/letter refers to and the first bit is all to do with the actual casing.

all the other numbers are to do with ratio and sensor type and when it was designed.