*HOW TO* Final Drive Swap for an F10/F13 Gearbox
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.
