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View Full Version : *HOW TO* Final Drive Swap for an F10/F13 Gearbox



Stuart
22-02-08, 01:00 PM
I appologise for no pics.... Maybe someone can follow the guide and do the honours for me :D

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# Author: Stuart Lindborg (Cambridge) #
# Date: 2nd March 2005 #
# Contact: lindborg.stuart@googlemail.com #
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The FD (Final Drive is the last gear ratio seen by the gearbox before transmitting the drive engery to the wheels. This gear is permanently engaged so even when you change gear it still gets used, also applicable to reverse gear too. A low numberd FD will give the car better top speed over a greater numberd counterpart but you lose acceleration due to the leverage force needing to be greater to give similar results, conversely the higher numbered FD's give better acceleration but at a cost of top end speed. Also if you fit a greater numbered FD then the ability to wheel spin is increased due to the increased leverage force to the wheels (torque), so yes you could shave a few tenths off a 1/4 mile time or a track time but you could then lose that gain by losing grip, its worth considering that. Although we have seen time and again that the fitting of a 4.18 FD to most novas gives it a totally new lease of life and makes it much more fun to drive as there is always good acceleration to be had from the gearbox.
This guide also demonstrates how to change the gear clusters over if you wish to fit a different "selection" of gears in from the F10/F13 WR/CR ranges, just ignore the FD swap bits and possibly the removal of the Differential as you might not nessecaraly need to remove it if the FD is the same, or your changing the pinon gear from your previous cluster.
Available FD choices
3.74 (least acceleration, but highest top speed)
3.94
4.18 (most favoured as it gives a nice blend of acceleration and top end speed) 17T on small gear (pinon) and 71T on Crown Wheel (big gear)
4.29 17T 73T ***check on EPC ******
4.53 (most acceleration and low top speed, and lots of wheelspin from standing start)
Others maybe available from a gear supplier such as Quaife etc
This can be done with the gearbox in the car OR out of the car (Obviously its easier out of the car, but beggers cant be choosers)
If you want a haynes style "spanner rating" id honestly say it was a 2.5 spanner job. Maybe 1.5 with box out of the car. Its more time consuming than difficult.
Weather you have acess to ramps or not, the procedure is the same, its just easier if you have ramps.
Stuff needed:
Soft Beverages (alcohol and car repairs are a bad idea)
Food, and maybe a maccy D's break in the middle (other fast food outlets available)
Radio (select desired genre of station)
seriously:
2 or 3 Legged Puller
WD-40 or duck oil, and some grease.
1/2" drive socket set (3/8" will do) ranging from 8mm - 22mm.
Breaker bar to suit above set.
Spanners (An adjustable will do).
A Length of Angle Iron (25*25*3-5mm) approx 2-3 feet long (for the diff "nut")
Hammer(s)
Circlip Pliers (External vital, internal an option)
Sturdy Flat bladed Screwdriver (for levering)
Jack/Axel Stands
RTV/Instant Gasket Silicone gooooooo
approx 1.8 Litres of Gearbox oil

Procedure (in the car)
Im going to run through with the basics incase some folk arent as aufait with stuff like this as others.
Slacken all 4 bolts on both front wheels (or 5 if youve been mad enough to go 5 stud)
Place Hand brake on and chock the rear wheels (safety first)
Jack both sides of the car up and place on stands, id say higher the better, but its your call on that one.
Remove the front wheels and place under the car behind the stands (just incase) or just anywhere out of the way.
If you have your anti roll bar fitted, remove this (and throw it away, but thats another discussion).
Slacken off the front tie bar nuts (22mm), if they havent been removed before then soak in WD-40 (or similar) and leave for a while.
Remove the Tie bar nuts.
Undo the inner TCA bolts (15mm ish), they are the bolts at the other end of the arm that has the ball joint/hub on.
With a little wriggling and moving about the tie bars should come out of the mounts and the Track Control Arms will be out of their mounting positions. this will enable the steering knuckles to "float".
With assistance get someone to pull each hub with sharp jolts and you pry at the CV joints in the gearbox (be aware some fluid may drip/run from the box at this point). Do this to both sides and then chock/secure the hub,driveshaft,suspension unit out of the way without placing excess stress on the parts.
Break - Time for a beverage and a snack
Get a large tub under the differential acess plate (diff cover) and loosen off the diff cover. Be warned, lots of fluid will come from this, and it stinks.
Take the diff cover and inspect the film of oil left on it, if the glitteris gold in colour then a brass baulk ring has failed, if the glitter is silvery then something could be faulty with a bearing or synchro (but thats less common), the remedy to the baulk ring replacement is coved in another guide. Wipe the cover clean (both sides) and clean the gasket surface while you wait for the gearbox oil to drain properly from the diff housing. Also clean upo the bolts, remove all traces of oil and sealer from them.
Break - Banter with mates/food time
Once all bar a few drips of oil has drained from the box you can commence the removal of the diff itself. On the passenger sied of the gearbox there will be a 10mm bolt holding a small piece of metal in place, this metal acts as a lock for the big castelated nut that holds the diff in place. Remove this bolt and the metal locking piece.
Mark the location of the castle nut in relation to the diff housing. Using the angle iron place it across the diff nut and apply pressure to hold it in place, while doing this undo the nut. Its very very stiff, and seems to go on for ever. This will take a fair while but hey. Oh be carefull as the bar WILL slip every now and then!
Once the diff nut is out, place it to one side and wiggle the diff about inside the casing to get it out. be carefull not to damage the plastic gear on the narrow end as this is your speedo drive.
Break - Admire your work thus far, and drink beverage
With the diff out you can move onto lowering the gearbox to gain access to the endplate. To do this you place your jack under the main body of the gearbox and just support it, but not the car. Undo the front passenger side engine mount and remove the bolt, let the jack down slowly until you can see all of the bolts around the end casing of the box.
Look in the engine bay from the top. you will see the selector ontop of the gearbox, undo this and remove it. Slip the linkage pin out of the linkage-selector section.
Again clean up the sealing surface and the bolts.
Back to the passenger side under the Wing.
Undo the nut holding the earth strap to the box, sometimes the whole bolt will come out. Thats not a problem, just remove the strap from the body of the car too.
then proceed to undo all the bolts on the end of the casing. there are 2 different size bolt heads, the amller ones dont hvae to be removed, but you may wish to reseal the cover properly in which case you do need to remove these.
With all the bolts removed tap the immediate end cover with a hammer to coax it off. this will reveal 5th gear and the input shaft access hole (to pull the shaft if your changing the clutch). More gearbox fluid WILL leak from here, so place the tub under here. Again clean the bolts of oil and silicone, as too with the cover.
Were nearly there with pulling the cluster (the actual gears) from the box. You may find you need to hammer at some of the lugs to get the end plate free, but be carefull, ive knocked the lugs off before now. DONT try to poke a screwdriver into the join as this will damage the sealing surface. When its seperated more flud will leak, so again be prepaired.
Once the cluster is "free" the slide it out, be carefull not to let the magnet go walkies nor the washer with a D shapped hole in it. Be ready to catch the gears as the shafts are removed from the bearings. They wont fall all over the place, but the will drop due to the imbalance of it. Place the cluster on a work bench or a sheet over the floor.

Stuart
22-02-08, 01:01 PM
I think lunch could have been earnt by this point.
To recap, you have your diff acess cover plate, diff, castle nut, 5th gear cover plate, gear cassette and selector + a bunch of bolts+nuts on the side with you.
Place the gear cassette so that 5th is on the bench, ie you have two shafts about 10-15" long pointing up at you. You will see there is a smallish gear at the end of the main shaft (the input shaft is the one with the long narrow splined part), this is the Pinon of the FD setup. To remove this you will need to take off the circlip that is on the top of the gear, and then remove the gear itself, most of the time it will slide off by hand, but on occasions ive known them to need lots of wd-40 and loads of puller work. I guess its the luck of the draw.
With the gear off, note the orientation of it as the "new" one has to go on the same way. You may wish to count the teeth of the one youve removed and compare to the one your fitting and verify with the info at the top. Fit the new gear on the shaft, you may want to apply a small ammount of copper grease to ease the removeal process next time. Once in its rightful place refit the circlip.
Clean up the sealing surfaces of the end plate, both sides, ensuring all the oil and dirt is removed from the surface. You will also want to cleanup the magnet, be careful as there may be swarf on it and you might get that stuck in your fingers/thumb (it fecking hurts a few days later). With that clean, and the sealing surfaces clean you can apply a bit of silicone to the magnet then "stick" it into its location in the end plate.
Place the diff in a vice and undo the bolts securing the crown wheel to it, note the orientation of the gear on the diff prior to removal, again you might want to count the teeth to ensure you have the desired one.
Fit the new crown wheel to the diff and bolt up tight and progressively, if your paranoid then use a bit of thread lock, but its not vital.
The diff can be refitted into its housing and the big ole diff nut can be wound back in to be just short of the position it came out of, refit the locking tab and bolt while your there.
Break - Drinks and food again
Time to put her all back together again.
Ensure the gearbox sealing surface is all clean and debris/damage free, maybe wipe the inside of the box to be sure there isnt a chance of oil getting to the sealant before its set. Apply a bead of sealant around the gearbox seal surface and also apply a bead round the gear cluster seal surface (top one with the majoroty of gears on it), if you sprung for the gasket set place the gasket on the silicone and apply more to the top of that. apply a little grease to the washer with a D hole in it and place that on the shorter shaft that has the reverse gear on it (its the straight cut gear as opposed to all the others that are helical cut), add mroe grease to this washer/shaft to ensure it stays on!!
Here comes the tricky bit, offering up the gear cluster to the box without disturbing the silicone, you need one hand on the gears and the other holding 5th gear (another person could be uselfull) make sure the washer (with the D shaped hole) stays in place and push the cluster home, you can refit some of the shorter bolts that hold the cluster in place.
Clean up the 5th gear cover plate sealing surface on the box and them apply sealant to that, the cover and the gasket if you got one. Put that in its appropriate place and then refit all the bolts. Do them up in a circular pattern to ensure the seal gets clamped up evenly. Once all the bolts are in nice and tight you can refit the earth strap, this could be the ideal time to renew this as its sometimes a cause of electrical faults. You will notice that there is lots of sealant around the joints as its been squeezed out, I recomemend running a blunt blade round to try and smeer the extra sealant over the joint to try and make sure the box seals (they nearly always leak).
Break - feel smug as youve not got far to go
Jack the gearbox back up to its proper location and bolt the mount back in. The jack can be removed now.
Clean up the diff cover seal surface and apply sealant to that, and the cover, and the gasket if you got it. Put a bolt in the front and back hole of the cover to make offering up easier. Once you have caught both threads you can fit all of the bolts and progressively tighten them to make the seal consistent. Again smeer the excess sealant around the join to assist the protection.
Wait 1-2 hours approx to let the sealant go off to a satisfactory ammount, in the mean time refit the drive shafts into the diff, then refit the TCA and tie bar into their appropriate locations. Copper grease on the TCA bushes might be favourable to help reduce wear. Bolt up the components appropriately to ensure secureity.
Refit wheels, lower the car back to earth. Ensure the wheel nuts are torqued appropriately
Undo the gear box level plug that is located just behind and above the passenger drive shaft in the housing. pour approx 1.8 litres of suitable gearbox oil into the selector hole in the top of the box, when oil starts to run out of the level hole, stop adding oil and refit the plug (ptfe tape can help ensure a seal).
Clean up the seal surfaces for the selector and then sealant/gasket that and refit the bolts. Reconnect the gear linkage. Double check that you have the bung in for the gear selector setup pin as its been forgotten in the past and caused the entire oil content to "fall out" through that tiny hole.
Leave to stand for approx another hour, observe any leaks and apply extra sealant as nessecary.
Take her for a spin to see the difference.
Keep an eye on the gearbox oil level and check the bolts are tight too.
Enjoy.

Version 1.01
email address updated 18/09/2007

John
04-04-09, 08:39 PM
Stu, does the f10 cwp fit the f13 diff? likewise for the gear?

Anyone know what the 4.18 is commonly found in? f10?

And lastly, are all f/d ratios stamped on the casing?

Stuart
05-04-09, 09:44 PM
the FD ratio "should" be stamped on the casing, but with all things GM never trust entirely what it says on the tin ;)

yes F10/F13/early F15 CWP stuff is interchangeable

16v Nova Kev
18-01-10, 01:00 AM
pic of a 4.29 final drive random i know.
http://i244.photobucket.com/albums/gg8/16vnovakev/SDC11671.jpg

milko96
04-06-10, 08:48 AM
Can I swap the diff from a F13 Nova GSi box onto an F15 box Corsa Sport box (both have 3.74 FD)?

If so is it just the diff I need to swap (ie the first few steps in the how to above)?

Stuart
04-06-10, 10:44 AM
In theory yes.
Dont quote me if its not 100% right lol

milko96
04-06-10, 10:43 PM
Haha... I wont.... honest!

milko96
05-06-10, 02:55 PM
My diff wont come out, drive shafts out, big nut undone.... is there something I'm missing or that could hold it in place, ie other gears?

Came straight out the other box!

mowgli
05-06-10, 09:20 PM
clout it

milko96
05-06-10, 09:42 PM
Haha, believe me I wanted to!

Had to pull gear cluster out slightly for it to clear and drop out... not sure why, unless box is goosed.... not drove it yet.

w88rdy
05-06-10, 09:45 PM
Did it come out of my old box ok pal?

milko96
05-06-10, 09:59 PM
Did it come out of my old box ok pal?

Yeah yours came out fine bud, it was the diff in the f15 that wouldnt come out.... swapped em over now, but were not 100% its right....

Test drive 2moro....

Dod
06-06-10, 08:14 PM
Update coming.

Stuart
18-05-11, 08:32 PM
http://www.pngclub.com/forum/showthread.php?t=169296&highlight=notch