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6 speed LSD Mk1 gearbox build
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PW@Woodsport
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PostPosted: Sat Jan 12, 2013 5:49 pm    Post subject: 6 speed LSD Mk1 gearbox build Reply with quote Reply with quote including images

As you may or may not know i do offer this gearbox conversion for customers of mine, but i thought i'd write a "how to" build thread for any of you that fancy having a go yourself.

So if you want to have a crack at building your own 6 speed gearbox with LSD this will be a pretty good guide for you.

This gearbox will be a direct replacement for your 5 speed, there is nothing to modify on the car itself, but you will need to use Mk2 NA driveshafts with the LSD, but don't worry it's still all plug and play.

Hope some of you find it useful, enjoy!

I haven't included the work stripping the 6 speed box or the Mk1 box down to their component parts, this is just the new 6 speed Mk1 gearbox build up.

So we start with our Mk1b bellhousing, this has to be a Mk1b item, a Mk1a housing is not compatable with this conversion, you can identify a Mk1b gearbox because it has two starter motor locations on it, a Mk1a only has one. So this has been steam cleaned and degreased with all bearings removed.



This is all of the 6 speed internal parts from the donor C60 gearbox...



Here are all of the new bearings and seals from Toyota, nearly 400 worth, not a lot for the money but essential if this is to be done right.



This gearbox is getting the Mk3 LSD unit, so the first step is to remove the old bearings from the Mk3 LSD...



The Mk3 speedo cog is the same as a Mk1 cog, so the speedo will work as before.

Now install the new bearings onto the diff...



Now fit the 6 speed crownwheel onto the LSD, for the non LSD version you use the MK1 diff and Mk1 crownwheel which is also the same gear size but a different bolt PCD...



Now we fit the original diff washer into the case, this one is a fixed 2mm width, we adjust the preload on the diff by changing the thickness of the opposing shim in the other half of the case....



The new bearing race is then fitted...



Now we install the new output shaft bearing...



Not forgetting the retainer and bolt...



Now we fit the new input shaft bearing...



The adjustment shim is fitted to the middle case, this shim is what affects the load on the diff...



And the new race fitted over that...



This shim will need to come back out if the preload is not correct.

Now to adjust the preload we need to install both the diff and output shaft into the case...





The mid case is then dummy fitted and all bolts torqued down as it would be on the finished box, the top snap ring is also fitted...



A 14mm headed M10x1.25 bolt is screwed into the top of the output shaft so my torque meter can be used...



Rotating the meter reveals how much resistance there is on the new diff bearings, if it is too much then the case comes apart again, top shim replaced for a slightly thinner one and the case refitted again, this process is repeated until the correct diff preload is obtained. For info, 0.05 shim thickness results in 3.5 in/lbs of difference to the preload, the shims are available from Toyota in 0.05 increments.

Now that the preload is correct we can start to build the gearbox up properly starting with the input shaft and one of the selectors...



The rest of the selectors are then refitted...



Then three selector retaining bolts are fitted...







The lower selector detent ball and spring are now fitted....





Fit the case magnet...



Now time for the reverse selector...





The reverse idler is now added...



The shaft on this needs to be orientated correctly to the case or the retaining bolt on the outside won't line up...



Now the case is ready for sealant...



With the middle case fitted and all bolts torqued down for the final time, the reverse idler bolt can be fitted...



Now both snap rings are fitted to input and output shafts...



Add the shaft retainer plate and bolts..



Fit the selector circlip...



Install both upper selector detent balls/springs...





Now add 5th driven gear...



The roller bearing for 5th....



Refit the 5th/6th selector fork and synchro hub along with circlip....



Fit selector fork bolt...



Fit roller bearing and synchro ring....



Refit 6th gears, top bearings and circlips....



Refit end casing...



Turn the gearbox over and install the inner bellhousing bolts, input shaft oil seal and release bearing trumpet...



The outer selector assembly then slides back in, add the Mk1 reverse light switch and that's it!
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Finn




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PostPosted: Sat Jan 12, 2013 6:12 pm    Post subject: Reply with quote Reply with quote including images

That is interesting. [salut]

What kind of gear/final ratios are we talking here compared to say stock Mk1b ratios?
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MartG




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PostPosted: Sat Jan 12, 2013 6:21 pm    Post subject: Reply with quote Reply with quote including images

Finn wrote:
That is interesting. [salut]

What kind of gear/final ratios are we talking here compared to say stock Mk1b ratios?


List here http://en.wikipedia.org/wiki/Toyota_C_transmission
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PW@Woodsport
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PostPosted: Sat Jan 12, 2013 6:34 pm    Post subject: Reply with quote Reply with quote including images

Sadly the information on Wikipedia about the C52 is wrong regarding the final drive. I can confirm that both the crownwheel on a Mk1b gearbox and a Celica C60 crownwheel are identical. So must have the same final drive ratio.

This is my definitive list of comparable ratios between the 5 and 6 speed...



Last edited by PW@Woodsport on Mon Jan 14, 2013 7:30 am; edited 1 time in total
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Finn




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PostPosted: Sat Jan 12, 2013 6:41 pm    Post subject: Reply with quote Reply with quote including images

Thank you, gentlemen. [salut]

Need to check first if I have a limited slip differential in my car and day dream then. [Embarassed]
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PW@Woodsport
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PostPosted: Sat Jan 12, 2013 6:42 pm    Post subject: Reply with quote Reply with quote including images

Some comparison graphs showing the key differences, both based on stock Mk1 wheel/tyre sizes and a 7,500 RPM limit.

Mk1b ratios....



6 speed...



Last edited by PW@Woodsport on Mon Jan 14, 2013 7:36 am; edited 1 time in total
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Ryan S
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1994 Toyota MR2 Mk2 Turbo Rev3

PostPosted: Sat Jan 12, 2013 6:44 pm    Post subject: Reply with quote Reply with quote including images

no 6 speed for a mk2 tubby??
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PW@Woodsport
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PostPosted: Sat Jan 12, 2013 6:49 pm    Post subject: Reply with quote Reply with quote including images

Yes that is possible, but it needs other supporting mods to make it viable which we are working on, but yes there is a Toyota 6 speed that bolts to the 3s-gte.

Did you get that AM2 issue sorted? I was consulting with Peter a lot about it, we bash heads together a lot on issues like yours.


Last edited by PW@Woodsport on Sat Jan 12, 2013 6:50 pm; edited 1 time in total
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Ryan S
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1994 Toyota MR2 Mk2 Turbo Rev3

PostPosted: Sat Jan 12, 2013 6:50 pm    Post subject: Reply with quote Reply with quote including images

PW@Woodsport wrote:
Yes that is possible, but it needs other supporting mods to make it viable which we are working on, but yes there is a Toyota 6 speed that bolts to the 3s-gte.



nice!!! keep us updated Paul [thumleft]
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PostPosted: Sat Jan 12, 2013 7:00 pm    Post subject: Reply with quote Reply with quote including images

PW@Woodsport wrote:
Sadly the information on Wikipedia ........ is wrong


Not unusual [Laughing]

( or could just be ratios for a different market - I think they supplied different ratios to the US for instance )
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Ryan S
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1994 Toyota MR2 Mk2 Turbo Rev3

PostPosted: Sat Jan 12, 2013 7:07 pm    Post subject: Reply with quote Reply with quote including images

PW@Woodsport wrote:
Did you get that AM2 issue sorted? I was consulting with Peter a lot about it, we bash heads together a lot on issues like yours.



sorry mate, only read half your reply, really need to get my eyes tested, no not yet, narrowed it down to basically 1 wire, just waiting on Peter calling to get the ohmmeter on it again before we start cutting wires, as it stands, Peter thinks it's a short in the wire that goes to the 2 pin plug on the coil, won't know for certain until we get the meter out again [Smile] can't wait as the car is stuck on my street with no MOT or tax, need to get it off the road [Shocked]
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PW@Woodsport
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PostPosted: Sat Jan 12, 2013 7:07 pm    Post subject: Reply with quote Reply with quote including images

Maybe that info is for USDM models or something? (just read your edit, yep that must be it)

Last edited by PW@Woodsport on Mon Jan 14, 2013 7:37 am; edited 1 time in total
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stenky




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PostPosted: Sat Jan 12, 2013 10:35 pm    Post subject: Reply with quote Reply with quote including images

C52 used in Celica AT200 has different final drive. It's different part number on EPC. This might be the reason why wiki says its under 4 and mk1b has more than 4 final drive ratio. However, this doesn't explain the lack of difference between C52 and C60 unit
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PostPosted: Sat Jan 12, 2013 10:35 pm    Post subject: Reply with quote Reply with quote including images

Great work, I tell you I'm not averse to wielding a spanner but that scares the cr@p out of me [Laughing] I think the fact that you share this info is often under-appreciated given other specialists most certainly wouldn't/don't - good on you.

Jon
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stenky




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PostPosted: Sat Jan 12, 2013 10:47 pm    Post subject: Reply with quote Reply with quote including images

I have disassembled S53 once, that thing is still in a box under the workbench [Very Happy]
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PostPosted: Sat Jan 12, 2013 10:54 pm    Post subject: Reply with quote Reply with quote including images

The Haynes comic for the AE92 Corolla quotes the 4.312 FD figure. Unfortunately their MR2 one doesn't seem to have any ratio info ( nor does their Carina E one ) nor does the US Chilton manual I also have.
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PW@Woodsport
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PostPosted: Sun Jan 13, 2013 8:56 am    Post subject: Reply with quote Reply with quote including images

jon_st205 wrote:
Great work, I tell you I'm not averse to wielding a spanner but that scares the cr@p out of me [Laughing] I think the fact that you share this info is often under-appreciated given other specialists most certainly wouldn't/don't - good on you.

Jon


Thankyou John, nice to get recognition for that, i always share all of my mods and discoveries with the Mk1 community, sometimes at my own cost when others often copy/pen it as their own.

It's not that scary when you take your time, there is a lot that can go wrong mind you and it only takes one small mistake and the gearbox won't work.

I think it's a great upgrade for the Mk1, i think more people should have a go themselves.

Any chance this can be added to the knowledge base or stickied? I think it's worthy.
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PostPosted: Sun Jan 13, 2013 12:17 pm    Post subject: Reply with quote Reply with quote including images

I don't need 6th gear but intend to add LSD to my C52 box, which is fully stripped down at the mo

I have a Mk3 LSD, complete with crownwheel

Equal length drive shafts could be another useful mod

Am I correct in thinking that is possible [Think]
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PostPosted: Sun Jan 13, 2013 1:13 pm    Post subject: Reply with quote Reply with quote including images

The Mk3 bearings won't work in the C52 cases unless you also fit the Mk3 races and redo the preload, i recommend you fit new complete bearings from Toyota.

The Mk3 crownwheel is totally different to the Mk1 NA crownwheel, you cannot use that with the C52 internals, and you cannot use the Mk1 crownwheel on the Mk3 LSD, the PCD is different, so what you need is a Celica 6 speed crownwheel to make that work, this will bolt to your Mk3 LSD but share the same diameter/tooth count as your Mk1 NA crownwheel.

The above is the only way to make a Mk3 LSD work in a Mk1b gearbox.

Equal length shaft setup is possible, i've done it many times, with your LSD you will need a left side Mk2 NA shaft on the passenger side, and on the drivers side you will need a St202 supported shaft, but you will need to put another left side Mk2 NA shaft onto that to keep the distances correct.

Once you get that far you will need to make a carrier bracket that attaches the supported shaft bearing to the engine block, this needs to be correct to 0.1mm or the gearbox oil seal will leak.
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PostPosted: Mon Jan 14, 2013 7:29 am    Post subject: Reply with quote Reply with quote including images

PW@Woodsport wrote:
It's very strange Mart, i keep seeing 4.312 listed as the Mk1 C52 final drive, even on pretty esteemed websites/Toyota clubs, they all list it as 4.312.... but in my experience it simply cannot be, the Mk1b diff crownwheel is identical to the C60 one in diameter and tooth count (different mounting PCD only)

Therefore a Mk1b must have a 4.529 final drive the same as the Celica 6 speed unit.

Maybe that info is for USDM models or something? (just read your edit, yep that must be it)


A fresh discovery has been made thanks to member "Gon" , after actually counting the teeth on a Mk1b crownwheel and output gear the final drive ratio was indeed found to be 4.312 as stated on many websites, so that information is correct.... this means the listed C60 (6 speed Celica) final drive of 4.529 is wrong, that too is 4.312 (as above Mk1b and C60 crownwheels are identical).

The Wiki was still wrong though, the table and graphs abpve have been edited accordingly, thankyou to Gon for actually taking the time to count the gear teeth, i should have done that ages ago but you trust what you read, i should know better!
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