how to remove a T-50 gearbox from a 4ag step by step

Tim.duncan

Active Member
Nov 11, 2008
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Snowy mountains
hey Lads

resident gtv owner and all round good guy Virg needs to pull out his gear box

this is a pretty rough off the top of my head step by step to help him get it done
hope it can be of assistance to others

This job is no worries on your own but having a few mates around can really speed things up, bribing with beer and/or BBQ is a sure winner to get some excellent "tool handing while your under the car" help along for the day

im going to assume if you own an AE86 you have some sort of mechanical knowledge and spanner spinning skillz so im not going to baby you through the step by step. Its a good idea to replace loose bolts a few turns back in the hole they just come from making putting everything back together MUCH easier. decent tools are also needed for this job a good 1/2 and 3/8 socket set are a good start and assorted spanners ect mainly you will be using 12,14,17,19 and a 24 socket for the drain plug. Also get a tom thumb oil jump for refilling the gear box

lets get started

*get the car up to a good height front and back, i use 4 jack stands but the front ones can get in your way so car ramps for the front wheels can be helpful

*Disconnect your battery (this is important and will make sense later do it first before you forget)

*before you get real dirty (and you will!) jump in the car remove the centre console and remove the shifter, it will be oily so have a rag ready to place it in and not drip on your lovely carpet

*drain oil from gear box

*remove the clutch master cylinder and tuck out the way

*unscrew the speedo cable and tuck out the way

*undo the reverse light cable and tuck out the way

*remove the 4 bolts from the diff end off the tail shaft (make sure car is out of gear and no handbrake so you can rotate the shaft)

*undo the centre bearing bolts but don't remove completely

*now the centre bearing bolts are loose undo them by hand while holding the tail shaft, the diff end should just come loose with a wiggle and then the yoke will slide out the back off the gear box. have a rag ready to wrap up the yoke and place the tail shaft to one side under the car

*place the gear box drain plug back in and remove the dirty oil

*undo the 2 bolts that hold the starter motor on and slide it out the way it should just rest on the motor, remove it completely if it dosent look happy sitting there (There is a decent power cable running to your starter motor if the battery is still connected you may see sparks fly in a bad way)

*cars differ with different systems but it can be a good idea to remove the exhaust system to give you more room and to allow the motor to move around on its mount a little easier

*undo the 4 bolts on the REAR gear box cross member but leave 2 in loose

*undo all the bolts around the bell housing .... sounds easy right .... most will be fine but a few can be tricky
the 2 bolts at the top of the bell housing can be a pain so leave them till last. Leave the two large bolts each side finger tight

*place your jack under the middle of the gear box, take the weight, and remove the 2 loose bolts in the gear box cross member

*now slowly lower the gear box down. have a friend keep a close eye on the back of your motor and make sure nothing will get damaged if the motor hits the fire wall

*now for those two top bolts, if you look up the trans tunnel above the now lowered gear box you should be able to see the top bell housing bolts, get every extension and uni joint you can find with your socket sets and hopefully you can get it long enough to get up to the bolts from between the gear box and trans tunnel

*remove the finger tight bolts and you are now ready to remove the box. Try not to force anything (if its not budging make sure you have ALL the bell housing bolts out.... its not to hard to miss one). side to side movements work well to get things moving. once you get a small gap between the gear box and motor start with a reward wriggle and it SHOULD..... should just slide off

*lower the box to the ground and slide it out from under the car

*high five your closest mate and have a cool beverage

for what ever reason you have removed your gear box there is a fair bit i would pay attention to while you have it out

~throw out bearing
~flywheel bearing
~gear box front seal
~rear main seal

inspect all these components and really they are all pretty cheap might be worth just buying them before you start and replacing them if needed

check out your clutch as it may need replacing
check you imput shaft of the gear box for excessive wear

Now to chuck it back together

*if you have removed the clutch you will need to re align in. use a good aligning tool (your finger does not count.... the best is a old imput shaft from a gear box if you can get one).

*get some anti seize grease put a touch on the swivel point of you clutch fork (not to much)
fill up the throw out clutch bearing housing slider thingymabob. there is a grove inside make sure that is full, same thing not to much excess.
and just a LIGHT smear on the spline


*get the gear box back up on the jack lie on your back looking up with both hands on the bell housing

*T-50s are pretty light but please don't drop it on your head as it will hurt alot !
get your mate on the jack handle and then lift the bell housing
this is tricky you will have to line up the imput shaft into the clutch try and get everything square and straight and it should slide straight back on (Do not force this step you will know when you got it right)

*hopefully the spline has lined up with the clutch and slid into place and you will have a 10-15 mm gap between the bell housing and engine block replace the two large bolts on the sides and slowly tighten them up DO NOT FORCE and keep an eye on the gap making sure everything is staying square
just easssseeeee it in if its getting hard or dosent feel right remove the gear box and start again

then its just a matter of putting it all back together

HAVE FUN!! if you find your self getting frustrated take a deep breath ....then make one of your mates do it instead

please feel free to add anything if you feel i have left anything out