Starlet KP diff..

[wde_bdy]

I still have pieces off my crownwheel and pinion sitting here. 7000rpm launches on sticky tarseal can do some big damage.

Callum

[Dr-X]

This is the diff from my bro's Falcon. This has happened not once, but twice, and the crownwheel/pinion has been reused both times.





Of course it's possible to damage the crownwheel and pinion, especially doing straight line launches - but if you're doing skids/drifts, or if you're just daily driving on a locker, the odds of blowing the crownwheel/pinion are incredibly minimal.

[wde_bdy]

Your comparing Falcon to Starlet though, all diffs have weaknesses in different areas. The ones I have blown and the blown ones I have seen are Starlet/Corolla ones.

Callum

[oem-r]

Well. im definate its the diff. so im looking for a replacement at the mo..would 40-50 be a resonable price for a replacement diff?

when inspectiing a diff, what things should i look and take into account when looking for a diff in good condition?

[rwd_mayhem]

i think purple_beasty is right.

wouldnt it be easier to replace the diff drum to drum, get a ke70 or something that will fit, then u will upgrade the brakes as well, and the wheels might stick out more either side.

[wde_bdy]

Is that $50 for a diff head or complete diff?
If its only the head be sure you get the same model as your current one. Refer to my previous post about determining what diff you have. If its the whole housing then it won't really matter what sort it is. Ke70 head will fit as I stated above but the whole housing will not bolt in as suspension mounts are different.

Callum

[oem-r]

not sure, he just said diff..i posted on the club-k forums, i asked him a few questions regarding what year starlet it was but hasnt yet to reply yet.

mines actually a 1982...which means KP60, right?

Say if i brought a replacement 5 speed diff head, out of a KE30 or 70, is it hard to replace a diff head than get a whole diff and replace that?

[AE85coupe]

just replace the diff head dude, cause KE70 and KE30 complete diffs aren't bolt in, the mounts are different

oh and Dr X on my AE85 i broke the crown wheel and pinion, just an 8 bolt diff, theres a fair chance it may be that, but you won't know till you pull it out

[oem-r]

yeah thats what i wana do, but as mentioned before it currently has a 5 speed diff, so i may as well find a ke30 or 70 diff which are 5speed and replace it.

ill confirm all this when i pull the diff out next week.

[AE25]

i broken a couple T series axles with a locker. they dont last for ever for sure.. mine due to axle splines wearing out and too much slop. managed to drive home the first time on the other axle, replaced axle and cleaned the head out.. put it back in. second time wasnt so lucky.. it peened the carrier and cracked the side bearing.

your 5speed doesnt really have anything to do with the diff. every car came with different ratio's and diff sizes. you should try get the same size, same ratio diff head as what was originally in your car to keep the speedo in spec (unless you've changed rolling diameter or something).

some things you could do to check for a broken diff without driving it..
jack diff up and sit it on axle stands or sit it on a jumbo trolley jack. let handbrake off.
if its a locker then if you spin one wheel the other one will spin same way without any restriction to movement. they should both spin at same rate.. if not then could have broken axle. if its jamming up then sounds like crown/pinion gears damaged.
if its open diff, other wheel will spin in opposite direction or driveshaft spins but either one should spin in a smooth manner. if not then sounds like spider gears or crown/pinion damaged. if you were to turn driveshaft then both wheels likely to spin same direction (but not always). either way there shouldnt be harsh operation.

replacing the head can be frustrating if you dont know how. especially if the axles dont come out easy and you dont have the correct tools.
put simply.. you need to drain the oil out. take driveshaft off, pull axles out, then lastly unbolt the head and remove it from the housing. that is often a bastard job. dont leave axles sitting in the housing as the weight of em will squash the end seals. also try not sit axle up on the wheel end if they covered in oil as if it seeps into bearing it thins the grease out.
must make sure no metal fragments left inside diff housing.
fitting is opposite of removal but make sure the gaskets are replaced or resealed. is a good time to replace any leaking seals

try find out what size diff and ratio you have.. its either the X series 5.6" or U series 6" - that refers to the crown wheel outside diameter. the diff ratio is how many times the driveshaft spins compared to the wheels.

if you have a jap import then the diff code should be written on the firewall chassis plate under 'trans/axle'... would have a code like X382 or U312 etc. if you have a 'made in thames' sticker on firewall or a date stamp where the trans/axle is written then its nz new and wont tell you the diff details.
to check ratio. with a locker... with diff in the air and handbrake off, mark a spot on the flange where the driveshaft bolts to diff and the diff itself so you can see how many times it has turned. do the same to a drum and the backing plate. then turn the driveshaft and count how many turns it takes to spin the wheels one rotation.. it should be somewhere between 3.3 to 4.5 turns. you could possibly get more accuracy by turning the wheel twice round and halving the amount of rotations of driveshaft.
if you have open diff then it a bit more tricky. you can do it by holding one wheel, probly easiest to sit it on a block of wood whilst the other wheel in the air. turn the driveshaft and count the turns but do two rotations of the wheel to get the ratio number.
if you happen to take diff head out then the ratio is written on the crownwheel. (may need to rub oil off to be able to see it) either in a 4mm dia circle with a number in it or will have a teeth count number like 41/9 which when divided will give ratio (that one would be a 4.55:1). once you know what it is you can try find one the same.
its not that important to find same ratio (well against law for speedo to be out) but is nice to keep speedo accurate if you have kept factory tyre size.
$50 is ok price. pickapart sell diff head for $42 in aucks.
can check wear by how much backlash there is between the teeth. it hard to explain how much is too much tho
em hope that helps? borrow or buy a corolla or starlet workshop manual for instruction on how to replace a diff head in detail.

[oem-r]

Thanks for another detailed and informative read AE25!!

yeah the speedo on the starlet is way out, im guessing this is because of different diff and bigger wheels. eg 75 is actually 55km!!

well ill try and find someone who can help me replace it as i dont think ill be able to do it as ive never changed one before. the axels, theyre the two metal bars coming out of each side of the diff in which the wheels are connected to right?

cheers.

will keep everyone up to date with the progress

Edit... just went outside to check info on the firewall chassis plate.

and the info are..

Frame n0: KP61 336366

Trans, Axle: K40 X332

[AE25]

yep axles are the metal bars that the wheels bolt to heh

sounds like a jap import starlet since it has the diff code.. X332 means it has the 5.6", 2 pinion open diff with either a 5.58:1 or 7.5:1 ratio which is really low!! rally cars often run around a 4.8 or 5.2 but 5.5:1 holy crap that must rev like a router! you sure thats not a typo?
follow the link to find out how to read the diff code
http://www.geocities.com/MotorCity/Pit/9975/dataBySubject/AxleCodes.html

are you in auckland?

[oem-r]

nice low gear ratios good for quick acceleration, but being only 4 speed and cruising along the motorway at 100 you can feel it revving quite high because of that!

im quite sure aye, maybe i exaggerated abit but say 70 reads as 50KPH.

not in auckland aye dude...windy and cold welly!!

[oem-r]

Ok i have gotten back from holiday, i have been offered 50 for a whole new diff set. would it be easier for me to replace just the diff head, or would it be easier replacing the whole diff unit??

[wde_bdy]

Depends on how seized up the bolts are, but generally swapping whole axle is easier than just the centre.

Callum

[TRD Man]

A KP Starlet pinion is pretty weak. It's quite possible that you've ripped the teeth of the pinion.

[AE25]

interestingly brad from club-k does a 13.7 1/4 with a modded 4age with the std starlet 6" diff (locked) hes only broken one head so far. just dont run big tyres on the back and stay clear of clutch dumps and lockers.. all depends how you drive!

[Muzzie]

I disentergrated everything on my first locker. Crown wheel blew apart. Smashed up anything and everything. Had like 1/4 of a wheel turn worth of slop though so I expected it, did't expect it to let go and JAM up on me at 80k though. That was .......... interesting to say the least.

I got my second locker is it now, and I have another whole drum to drum diff waiting for when i blow this one too

Shouldn't be too long, especially if I keep using it on taupo instead of meremere dirt track

[TygerTung]

I just pulled my axels out the other day, that put the tire on and kick it idea works great!

[oem-r]

Well finally got off my ass, got some axle stands and approiate tools and removed the diff, (was pretty easy) and took out the diff head and waalaa the diffs has striped off a few teeth off the gears..

all good scored another diff head for $50 which should arrive tomorrow and chuck it in and she should be running all good...its been 4 weeks

also would a diff head of a kp60 bolt straight onto my 82 kp61?