gearbox rebuild advice

[kamineko]

about to attempt to replace 3rd main and driven, all main bearings and all syncros.

what i don't yet understand is which part is usually replaced when the syncros are worn? [crunchy between 5th/4th but want to replace all while i'm at it]

i assume the brass baulk rings.. but about to order parts and would like to be certain. anything else usually replaced?

i've circled the main bearings i assume i need so far. (and 3rd gears)

sorry the forum resized these, click for 100%

cheers

[rockr]

items 21,33 and 27, all are lock nuts, helps to have new ones so when they are locked onto the shafts after torquing up they stay there, instead of reuseing the old ones which get damaged when they are taken off. replace all seals and gaskets, front axle seals are directional seals and are marked left and right , they leak if they are in the wrong side. the bronze baulk rings are normally all that is replaced when ya do syncros. while the gears are out id get them crack tested and shot peened ( if they not cracked) to destress them and get any dags from factory machineing removed (stops them working and coming of and being churned up in the oil), also check the clearance of the front diff while ya at it.

[kamineko]

Thanks

Another question, I have a diff i want to swap into a gearbox. for ease do i swap the pinion or the crown, (i wonder if bolting up a new crown onto a diff will alter its pre set alignment with the pinion.. or does the crown fit square on to the diff without play?)

am i making sense? i aim to do this the cowboy way and not need to adjust the backlash afterwards

[driftrex]

i could be wrong here but i thought the crown and pinion are matched gears, as in you cant use the crown from one gearbox and the pinion form another, must be a matched pair.

i know when i had to replace my synros and the 2nd gear set that this was the case, was told by speed-tech that i could get some whining by putting unmatched gears together. you certainly dont want a new gearbox that whines lol.

[kamineko]

yes i understand this, i have 2 gearboxes and i'm swapping the diff over, so i have the 2 matched pairs.

to keep the alignment between the two correct i'm pretty sure i can swap in the pinion shaft from the diff i want to use - but i want to know if i can swap on the crown from the diff i don't want

id rather just undo a few bolts on the diff instead of getting new washers and nuts etc for the pinion shaft

[driftrex]

 kamineko said:

yes i understand this, i have 2 gearboxes and i'm swapping the diff over, so i have the 2 matched pairs.

to keep the alignment between the two correct i'm pretty sure i can swap in the pinion shaft from the diff i want to use - but i want to know if i can swap on the crown from the diff i don't want

id rather just undo a few bolts on the diff instead of getting new washers and nuts etc for the pinion shaft

ah ok i understand what your doing now, i dont see that been a problem.

[rockr]

yes that will work , have done this but still checked the clearance and bearing area of the diff anyway , as i guess you will be useing the bearings with the diff you want with the old races in the box you want to use. doing this may upset the clearances etc always pays to check them if you chnage anything with them. have you got acces to a DTI and bearing blue???

[Guest]

Honestly, if you have never set up a diff before

Dont even think about it !

If you set it up wrong, it can seize (lock up) , whine , or even grind itself apart destroying every bearing in the gearbox

As for syncros (usually just the bronze ring is replaced) make sure you lap the syncro face on the gear and check new syncro operation before installing

The gears you circled are sold as 3/4 gear set which is 3/4 driven gear (H- Gear) with 3rd and 4th driving gears

Axle seals as noted are directional, use insulation tape over spline to prevent seal damage on reassembly of axle drives thru seals

The main bearings only require replacement if noisey or you got lots of spare cash

? did you find the key that locates 5th gear to shaft

Also did you find the key that locates 3/4 H-gear to shaft

[kamineko]

yar i found out about the gears being sold as a set.

have taken the easy route and bought a 2nd hand gearbox, have just swapped over the whole main shaft and driven gearset into my original case, keeping the original pinion and diff.

lol ichiban if i don't know then don't bother? sorry broken that rule a couple of times.. yes i'm aware gearboxes are complex and i have studied the workshop manuals, and taken apart broken boxes to learn how they work

anyhoo thanks for the advice people, can't wait to get this car back on the road

[Guest]

Many things you can suss yourself but somethings are best left alone

[funkytown]

 Ichi Ban said:

Many things you can suss yourself but somethings are best left alone

talking of which Rick - I have found a replacement box, mines nasty grauchy now - its getting worse. Worth splitting one open to check its in good knick? Or both?

[Guest]

couple of hours and some gaskets to check internals

Did it come from a known good car?

When you fly out? When do you want to drop the car off?

[DRFVDR]

I must agree with ichi ban

doing gearboxes are pretty easy BUT doing diffs can be problamatic in that to set backlash and the pinon to crownwheel matching is time consuming and requires at least a DTI to set correctly....

I have never done a subaru diff but have done a multitude of other applications and i know that even a half a thousand of an inch of misplacing can cause a diff whine(also if replacing only a pinion and not a set,had to be done as parts are no longer avialable)

[kamineko]

i also agree with what he's saying

however given the opportunity, the right tools and an experienced teacher i'd love to learn how to do it properly

[Guest boostcut]

you should just get some bearing blue and check it.... you never know.... it may be fine..

[Guest]

 boostcut said:

you should just get some bearing blue and check it.... you never know.... it may be fine..

Yeah but to an untrained eye, what sort of marking is he looking for !

Has the side bearing preload been set up correctly?

Too many variables and severe concequences if it turns to pooh

[Guest boostcut]

i thort they mite have some idea... too much heel/too much toe =pinion out. too much coast/flank pinion is too deep.

[Guest]

 boostcut said:

i thort they mite have some idea... too much heel/too much toe =pinion out. too much coast/flank pinion is too deep.

Yeah they might have some idea..... You dont ! ( too much coast - now thats funny)

Both of your listings of gear set-up are WRONG !

[kamineko]

easy guys..

[DRFVDR]

heheheheeh u make it sound so easy

remeber kaminko has never used bearing blue to check for gear matching

[kamineko]

lol i've used it, just not on gears

[Guest boostcut]

 Ichi Ban']

[quote name='boostcut said:

i thort they mite have some idea... too much heel/too much toe =pinion out. too much coast/flank pinion is too deep.

/quote]

Yeah they might have some idea..... You dont ! ( too much coast - now thats funny)

Both of your listings of gear set-up are WRONG !

Checking the Pattern

Check the pattern for proper pinion depth only after setting the backlash. Brush three or four of the ring gear teeth with a moderate coat of gear marking compound in two different places on the ring gear. Rotate the ring gear past the pinion gear three or four times and then back so the pattern can be seen.

Pinion depth is indicated by the position of the pattern between the face and flank of the ring gear teeth. Backlash must be kept within specifications, and will therefore only slightly affect the pattern between the heel and toe of the ring gear teeth. Housing alignment and pinion bearing bore alignment can also affect the pattern from heel to toe and can not be corrected without machine work. In some cases an ideal heel to toe pattern can not be achieved. If the backlash is within specifications, you may disregard the heel to toe pattern. A contact pattern that is centered from face to flank always indicates correct pinion depth even if a pattern that is centered from heel to toe can not be obtained.

If the contact pattern is towards the face of the ring gear teeth then the pinion is too far away from the ring gear. Adjust the pinion shims to move the pinion gear towards the ring gear centerline (add shims; subtract shims for pinion support designs). If the contact pattern is towards the flank of the ring gear teeth then the pinion is too close to the ring gear. Adjust the pinion shims to move the pinion gear away from the ring gear centerline (subtract shims; add shims for pinion support designs).

When changing the pinion depth, make large changes (0.005" to 0.015") until the pattern is close. By making adjustments that move the pinion too far, you can determine that the correct pattern is somewhere between the two extremes. Then make smaller changes (0.002" to 0.004") until the pattern is centered between the face and the flank of the ring gear teeth.

When setting up a used ring & pinion, pay more attention to the pattern on the coast side of the ring gear teeth and pay less attention to the drive side. Low mileage gears should be patterned as if new.

funny that, i dont know anything!!!!

[Guest]

Well done you can copy from a BOOK

Your orginal reference was to too much coast

Coast is a driving condition!!

Having too much coast does not = pinion too deep !!

To much heel / too much toe are opposites !!

[BC5RA]

It would seem that one of you is out of his depth.

Can we leave it to PM's please.

[Guest boostcut]

you dumb fuk!!!! do you never look in books?? oh thats right, your rick wheeler!!! the best mechanic under YOUR sun... your a baiting h o m o that is only on here to get a reaction and argue with people.

im only trying to help the guy get some idea of how complicated it can be setting a diff up.

thanks for your 2 cents but people do use different terms to describe things like coast.