Hi, was wondering if there was any advice I could tap into....
I have an open diff in the TII and while its sat on the garage floor I thought it would be a good idea to investigate the options..... oh and im not an intentional drifter.
Was reading from the 2nd gen section and I can see some options are
MX-5 diff (either 1.6 or 1.8) (strength?)
FD diff
Others??
RX-8 diff?? (is it different to the FD? Better or worse or even possable?)
I\'m not looking at kaaz etc cause I have a tight budjet, so is it even worth the swap? Use would be normal road use + the odd blast..
Last question, what kind of cost is invoved in this, if any one has any experience of this? (diff is on floor & I would be bolting it all back up) Or is the swap something I could undertake myself?
Cheers
IIRC the FD diff will fit... I think McPie on here has done the conversion... and kind of LSD will be worth the upgrade IMO.
im under the impression that the MX5 diffs are for the egi\'s.
I think the FD diff will be you\'re best bet. It will be more than fine for getting you round a track quickly. Cheaper option is to weld but i assume you wont want to do that, what a shame!!
Anyway, hows the FC coming along? I remeber the old project thread which i havnt see in ages!
Am I right in assuming that once you\'ve drained the oil, taken the back plate off, and remove the output drive shafts, the diff gear mechanism should just be removable?
So provided the FC drive shafts fit in the FD\'s torsen unit, you could just bolt this unit to the ring gear in the diff?
BTW - I don\'t know the answer - I\'m looking for the info as well ;)
Thanks for the reply\'s folks....
Project????? Oh yeah, I almost forgot :o:o:o lol
It\'s coming along got a lot of things done (well for me anyway!) Last weekend I made up some new brake lines (amongst others) for the rear and fitted them which look rather good and lined up perfectly which was a bit of a shocker! :D I stopped doing updates because lets face it - I was raving about fitting a bolt in the end!
I was thinking of welding it but the only thing stopping me was how the thing reacts on tight turns. I dont know anything aside from that about welded diff\'s (I wouldnt even know where you weld it or how much etc)
Ok so the MX-5 diffs are out, which is fine. Anyone know if the RX-8 diff is different / better / stronger than the FD one (is the FD torsen?)
From what you say Prof, it\'s tempting to fit one myself, I have heard of people doing it. So really its just sockets to open the thing (maybe a rubber mallet to crack the case off) and general tools to swap over plus some liquid gasket & new oil....hmm have to do some more digging........ I\'m sure i saw some pictures of someone doing one on here.
Im pretty sure the half shafts wont fit. I think they just slide on from memory, been a while since i was under an fd though. Maybe you can use the FC half shaft joins on the fd diff.
Couldn\'t tell you about the 8 diff. Might have a different ratio etc. No idea about the strength.
Changing a diff on an FC is a pain in the arse IMO. Entire subframe has to come out, i also had to half take off my rear hubs too. Youll need someone to give you a hand putting it back together i reckon. If you can leave it on the car that would be the best option.
As for the welded diff, I\'d find someone whos done a lot of them if you plan on getting that done. Its not a big hassle to drive with IMO. Harsh coil overs are much worse. Basically on tight turns (as in full lock at 3 mph) it acts as a brake and theres a bit of tire hop.Other than that there dont seem to be any drawbacks. Very predicable in comparison to an LSD
FC t2 diff is long-nose and 30 spline
FD diff is short nose and 30 spline
NA FC diff is long-nose and 26 spline
mx5 is long-nose and 26 spline
halfshafts are different on all of them,, and even unique between years of FC
-- VLSD ( s5 ) versions have unequal length inner shafts that are unique
and there is also revision part way through the standard FC t2 series shafts
the only thing that is going to swap is if you find a LSD pumpkin from an FD and refit your crown gears to it and stick it back into the FC nose
( using the already lapped to pinion FC crown is much preferred to using the same ratio crown from an FD )
if you wish to alter the ratio,,for 30 splines
3.9 is from FC/FD autos, 4.1 is in the manuals
and occasionally in some special models you will find a 4.30
( methinks the only FC 4.30 is US NA GTUs and so is a 26 spline smaller crown, not so sure about infini/efini t2 models )
else the 4.4 and 4.875 and 5.1 options will amount to fabbing a new tailshaft and diff nose cradle onto a commercial van/ute short nose diff
or by being tricky and welding a fabbed extension onto a short pinion gear for the T2 nose
- none of this easy or cheap,, and are not really good ratios for turbo cars anyhows
methinks there is a post somewhere on miata net and also on mazdatrix that shows the differences between the half shafts
if you wish to do the locker you must do it by just welding the spider gears to one another and to the case
and also a spot,, ( ground back so it clears when the pumpkin rotates )
to the ends of the pin that holds the spider gears
using the other drop in plate method is usually much stronger
but for FC you must remember that the half shafts are C clipped into place
- and any plate will negate you getting the clips back in
PS
penetrene/ CRC is you friend to limit spatter on oily parts
( even the mig will spit )
when doing so,, place the half shaft back in so as to protect the splines from spatter
http://www.mazdatrix.com/G8LSD.HTM
note the differences in half shafts
S4 post VIN 608385 and ALL S5 TII halfshafts are longer, stub shaft shorter
post VIN 608385 Longer halfshaft has to match 5 7/8" stub shaft
pre VIN 608385 shorter halfshaft has to match 6 1/4" stub shaft
http://www.mazdatrix.com/g7.htm
note on this page,, they advertise exchange pinion swaps ( and bill ) to make 4.875 and 5.1 long pinions up for you
and that P092-27-110B should come up as an FC t2 4.30 gear set
Quote from: Ricco_04;737238I was thinking of welding it but the only thing stopping me was how the thing reacts on tight turns.
It\'s not just tight turns, it\'s
any turns - think about why diffs do what they do in the first place!
I would advise against a locked diff in a tarmac car. We used to lock the Escort diffs but they were rally cars on the loose where the inner wheel could spin rather than drag.
The stress induced in the inner wheel when cornering fast in a medium turn will be phenomenal (it will try to twist your half-shafts... where\'s that force going to go?), and the induced understeer will be unwelcome.
Wow, thanks for the info - Think im going to have to read that a few times before I understand it! :2Confused :Laugh
The more I read up on it the more confused I seem to get. I was just reading that the UK TII\'s would be fine with it\'s standard stubby shafts & halfshafts and I just find conflicting info everywhere!
Back to more reading then.... (and youtube videos - video helps me lots lol)
Right, for me the welded diff is out and torsen is on the cards, if I can work it out :spank
Quote from: Ricco_04;737397Wow, thanks for the info - Think im going to have to read that a few times before I understand it! :2Confused :Laugh
The more I read up on it the more confused I seem to get. I was just reading that the UK TII\'s would be fine with it\'s standard stubby shafts & halfshafts and I just find conflicting info everywhere!
Back to more reading then.... (and youtube videos - video helps me lots lol)
Right, for me the welded diff is out and torsen is on the cards, if I can work it out :spank
If you figure out how to do it, post it up - I think a few of us may be interested :)
Ha ha, yes no worries - its a big learning curve for me but I will be happy to post something up when my poor brain can get over it!
Oh I feel kinda stupid asking but what is the \'pumpkin\' thats been mentioned above ???
That\'s the big round part of the diff - it looks like the front cone shape bit can be detached from that part - at least on some diffs. So the pumpkin actually houses the differential gears themselves. The actual working part is I think called the \'gear case\' and that has the ring gear attached to it - that\'s where the power comes in from the pinion driven by the prop shaft.
The two drive shafts come out of the \'Gear Case\' - which is where all the magic is done ;)
I still think I have a viscous diff - if I rotate one back wheel slowly, the other goes the opposite way, bit if I rotate one wheel back and forth quickly, then just in one direction, the other wheel comes the same way.
pumpkin is the bit the crown bolts to,, holding all the spiders
ie pumpkin head , with a crown on it
nose= the bit that unbolts from the tube ( if solid axle ) with the pumpkin , pinion, spiders and crown inside
pinion gear- input gear
crown- output gear
YOU CANNOT PUT A FD DIFF NOSE INTO AN FC WITHOUT MAJOR MODS BECAUSE ITS A SHORT NOSE AND FC IS LONG NOSE
sheesh-- how hard is that to grasp ?
THE PUMPKIN SWAPS , AS LONG AS YOU USE YOUR FC PINION AGAINST IT
PRUDENTLY THAT ALSO MEANS THE CROWN GEAR TOO
because only idiots put a ( FD ) crown to a foreign ( FC ) pinion as they are not lapped together
and obviously if there is a ratio difference they will not work either
smart men will see i am telling you to use the FD LSD PUMPKIN and the FC crown and pinion in the FC nose
for this you need the FC s4 stubs and half shafts ( matched pair , knowing the VIN date change )
s5 stuff must be the open diff,, cause VLSD have unique stub lengths
if you want the hella short ratios,, you need to make a long pinion gear from a short one , requires welding and machining ( cause NOT AVAIL in long pinion ) and is an obvious fail point
else you have to use a short nose van/ute diff with major mods to the diff mounts, tailshaft and internally for the c clips
too basic , if you cant work that out,, you need to go to a shop ,one who can see the obvious
Quote from: bumpstart;737514pumpkin is the bit the crown bolts to,, holding all the spiders
ie pumpkin head , with a crown on it
nose= the bit that unbolts from the tube ( if solid axle ) with the pumpkin , pinion, spiders and crown inside
pinion gear- input gear
crown- output gear
YOU CANNOT PUT A FD DIFF NOSE INTO AN FC WITHOUT MAJOR MODS BECAUSE ITS A SHORT NOSE AND FC IS LONG NOSE
sheesh-- how hard is that to grasp ?
THE PUMPKIN SWAPS , AS LONG AS YOU USE YOUR FC PINION AGAINST IT
PRUDENTLY THAT ALSO MEANS THE CROWN GEAR TOO
because only idiots put a ( FD ) crown to a foreign ( FC ) pinion as they are not lapped together
and obviously if there is a ratio difference they will not work either
smart men will see i am telling you to use the FD LSD PUMPKIN and the FC crown and pinion in the FC nose
for this you need the FC s4 stubs and half shafts ( matched pair , knowing the VIN date change )
s5 stuff must be the open diff,, cause VLSD have unique stub lengths
if you want the hella short ratios,, you need to make a long pinion gear from a short one , requires welding and machining ( cause NOT AVAIL in long pinion ) and is an obvious fail point
else you have to use a short nose van/ute diff with major mods to the diff mounts, tailshaft and internally for the c clips
too basic , if you cant work that out,, you need to go to a shop ,one who can see the obvious
So if you have a TII you need to do the following ??:
- Get FD pumpkin or whole diff and discard the nose.
- Swap FC crown onto the LSD from the FD, as it needs to mate with pinion gear from FC nose.
- Get FC Series 4 stubs and half shafts (or Series 5 open diff)
- Bolt FD pumpkin back onto the FC nose
- Put S4 stubs in and put new clips and oil seals
- Bolt up half shafts
If I\'ve understood this correctly?
bingo red leader
tally ho
Garage up yer FDs - there\'s a marauding herd of FCers with a bunch of spanners roaming the streets... ;)
Now that is funny :rollin
Good stuff folks, all sorted. Just reading up on backlash now :)
good show old chap :Thumbs-up
hi m8 do u still want the thermostat? mick
Bit more progress I now have a Torsen diff from an FD (Cheers to Craig)
Going to get a few quotes to set it up, in the meantime I will clean it all up and probably get it all in the FC case.
Cool... got pics? :)
This would be good with step by step pics and then sticky as this would be a good mod for a lot of people.
I agree I\'d defo be interested.
Planning on spannering on Sunday, I will have the camera handy. Once it\'s all bolted up in its new home I will be taking it to a mates workshop to have a look at setting it up. If it all goes successfull then I will put details up :)
Just wanted to shout out for the section that coveres the differential in the workshop manual, does anyone have that section on a pdf? :wave
I thought they where on a sticky but cant find them :o (yes I fail :Laugh)
google is you\'re friend !
http://www.rotaryheads.com/PDF/2nd_gen/
there you go, has links to each section and even each chapter which saves scrolling!
Ah mucho thank you :cheers
More bedtime reading!! :Snoring
I hope it goes well!
Interesting thing I\'ve only just put into real though was how much grip I\'m getting with my welded diff. I NEVER struggle for rear grip, wet or dry, and I\'ve only got 225\'s. My friend with a Z4M spins up his 265\'s easily, just pulling away moderately in the wet, whereas I\'ve got a HUGE amount of grip.
But it DOES help promote understeer, I\'d admit. But if I had good front tyres, not budget ones it\'d probably be a lot better.
Ive been running an fd diff on my t2 for about a month or so with the fc stub shafts,crown,pinion etc Seems 10x better than the open poo it came with.
Quote from: Adam fc;739959Ive been running an fd diff on my t2 for about a month or so with the fc stub shafts,crown,pinion etc Seems 10x better than the open poo it came with.
Adam,
was that with the FD pumpkin and the EGI shafts ?
"Open diff, bad. Locked diff, good. Slipper diff, awesome."
"Open diff, bad. Locked diff, good. Slipper diff, awesome."
"Open diff, bad. Locked diff, good. Slipper diff, awesome."
Me want one! ;)
Quote from: Prof;739963Adam,
was that with the FD pumpkin and the EGI shafts ?
No it was running the standard uk tII stub shafts and pumkin with no problems till my worn pinion shaft bearings let go lol.
I was gonna say, the UK stub shafts are the correct length (or in tolerence I should probably say!)
Had a scan through the PDF (I have the book but just couldnt find it :spank) and its got all the info I could dream of (all 26 pages of it!)
The Diff is all swapped over, just got to start measuring things to get it properly setup now :)
Quote from: Ricco_04;740286I was gonna say, the UK stub shafts are the correct length (or in tolerence I should probably say!)
Had a scan through the PDF (I have the book but just couldnt find it :spank) and its got all the info I could dream of (all 26 pages of it!)
The Diff is all swapped over, just got to start measuring things to get it properly setup now :)
Any pic\'s ?
i did it too! picked mine up for 150euros
(http://public.bay.livefilestore.com/y1p6Qz-VtsxB5gpCfeKJAIPZLaKRMspl4Di-5hyg_XqrSu6jCQtSxS9I9YJnUUEtPHES5CmkHF3ax4Hdz-hCeX6Ag/P1000448.jpg?psid=1)
You got all yours set up Furb?
Or you going to try it as it is for now?
i have the FD diff for about 2 years now! i love it :D
destroyed one already due to lack of oil, had a leaking seal that i did not know of.. :lol:
2 years!!! Ok your well ahead of me!!! :Giggle
Did you get it setup or just swap them over?
Quote from: Prof;740288Any pic\'s ?
Was going to write up so here is a couple - its very easy to do - the hard work will be in the setting up :)
(http://i16.photobucket.com/albums/b10/effazef/Project%20TII/IMG00208-20110130-1531.jpg)
(http://i16.photobucket.com/albums/b10/effazef/Project%20TII/IMG00221-20110130-1615.jpg)
i swapped them and did the gear alignment myself, as i am an engineer this was not that big of an issue :)
Quote from: Furb;740295i swapped them and did the gear alignment myself, as i am an engineer this was not that big of an issue :)
Ah fair play, I suppose being an engineer made things a bit easier ;)
well actually being an engineer made me cheat :Giggle:Hammer
because i KNOW how gears need to be aligned, in my previous job i did a lot of that in gearcases of factorysize printing presses.
i did NOT measure the gears in the diff, because i dont have the tools to do it at home. i just went with gut feeling..
but when I took the wrecked diff out, the wearmarks on the gears were perfect!
Well if you dont have the tools then I guess I definately dont! Better get a quote to get it setup and cheat my way! :Nono! (Gut feeling for me may end up in a "oh bugger, thats not ment to do that" moment
haha yeah, then we have another "clunking/rattling noise in the rear" topic :rollin
Is it not just a case of marking everything up before you strip it. Then rebuilding it to suit making sure you align everything up again? Making sure there is no play or tight spots in it.
well, in fact it is..
but as you replace the entire diff with another unit, the alignment is not exactly the same as it was before. there are always minor differences
Thats what I thought. So just to clarify then. You can use everything from the TII diff, half shafts etc. All you do is split it an pop the FD internals in the way the FC ones came out. Put it back together and fill it with oil.
It does look like you could replace the actual diff unit with the one from the FD - and just unbolt the ring gear from the FC diff and put it on the FD torsen - then your pinion gear will mesh nicely.
Does the torsen have the same number of splines as the FC unit then ?
Quote from: TiddlesRX7;740358Thats what I thought. So just to clarify then. You can use everything from the TII diff, half shafts etc. All you do is split it an pop the FD internals in the way the FC ones came out. Put it back together and fill it with oil.
Depends what series FC you have as the stub shafts can be different lengths
Quote from: Prof;740371It does look like you could replace the actual diff unit with the one from the FD - and just unbolt the ring gear from the FC diff and put it on the FD torsen - then your pinion gear will mesh nicely.
Does the torsen have the same number of splines as the FC unit then ?
Yes it all just swapps over (stub shafts aside) As in another post, the real work is setting it up properly :)
actual diff?? as in just get a fd diff (pumpkin with fd bits in it)?
whats a ring gear? crown?
then just chuck into an fc tii 1990?
whats this thing about lining / marking points?
sorry if they dumb questions and have been answered before.
The first three of your questions are answered in the first page of this thread.
As for the lining/marking points, after you install the diff and before you assemble the case, you need to set the backlash and tension. First you set the tension by screwing in the two rings and then you set the backlash by screwing both rings at the same amount towards the same direction. You go by the FSM. You will need a dial gauge (micrometer) and gear marking compound, to test and verify afterwards that you have it set correctly.
Basically what you are trying to do is keep the bearings under slight load to each other so that when the torque path changes (pinion to ring and ring to pinion) the carrier won\'t shock around. Backlash is set to ensure that the pinion and ring teeth mesh correctly, that is at the center of the area of each tooth.
Quote from: infernal;763501The first three of your questions are answered in the first page of this thread.
As for the lining/marking points, after you install the diff and before you assemble the case, you need to set the backlash and tension. First you set the tension by screwing in the two rings and then you set the backlash by screwing both rings at the same amount towards the same direction. You go by the FSM. You will need a dial gauge (micrometer) and gear marking compound, to test and verify afterwards that you have it set correctly.
Basically what you are trying to do is keep the bearings under slight load to each other so that when the torque path changes (pinion to ring and ring to pinion) the carrier won\'t shock around. Backlash is set to ensure that the pinion and ring teeth mesh correctly, that is at the center of the area of each tooth.
Fantastic explanation - I read the FSM and really didn\'t understand it at all!
This gear marking compound - does it require the internals to be free of oil (as in clean) in order to work?
Quote from: Prof;763517Fantastic explanation - I read the FSM and really didn\'t understand it at all!
This gear marking compound - does it require the internals to be free of oil (as in clean) in order to work?
Hehe sometimes the FSM is ommiting valuable information and just sticks to the numbers... But for DIY numbers are inadequate! ;)
As for the gear marking compound, I sprayed and wiped the ring gear (nothing else) with a bit of brake cleaner prior to applying the compound, just to be sure.
Also after I finished, I removed the leftovers of the compound with a soft copper brush and I flushed everything with the old diff oil I had removed before.
The compound makes small chips and I didn\'t feel like letting it sit inside. Some people tell me that they don\'t wipe it or clean it at all and there is no problem, but to me it feels wrong, especially for the torsen and the bearings. :Thumbs-up