How to convert a c160 box for mr2 AW11

[AdrianS]

This is how I converted a c160 gearbox from a JDM AE111 (1999 Trueno BZR) for use in an AW11 MR2.

It uses a selection of c60 (celica) parts purchased new from Toyota, as I did not want to gut an MR2 (c52) gearbox.

Thanks go to Aaron Willis (Lithia Toyota, Oregon) for help with parts choice.

You will need :

c160 gearbox complete with selector assembly.

c60 parts, with Toyota part numbers (assembly number in brackets) :
selector shaft : p/n 33261-20080 (33261C)
inner no 1 shift lever: p/n 33252-20060 (33251A) Correction: part# 33251-20060
inner no 2 shift lever : p/n 33252-20030 (33252A)
shift interlock plate : p/n 33266-20030 (33266C)
oil seal : p/n 90310-15002 (33261H)
dust boot : p/n 33531-17010 (33531B)
spring #1 : p/n 90501-16167 (33276F)

I also purchased a new end cap, but you could modify the c160 one by welding a cap on it.
selector end cover : p/n 33506-20280 (33528B)

Here is the c60 selector mechanism :


Here is the c60 end cap (with integral reverse lockout) :

to be continued...

[AdrianS]

To adapt the c160 for mr2 usage, the selector shaft must exit from the opposite side of the gearbox.
This means the case has to be drilled for the c60 selector shaft, and a new oil seal carrier must be made and fitted to the box.
I also made a drilling jig to center the hole you need to drill in the casing.

These are the parts I had fabricated :

The tolerance for the oil seal is a bit tight; the ID could be increased by 0.1mm to make the seal an easier fit.

Here is the drilling apparatus : I used a Bunnings drill extension, and linished the chuck end down by about 1/2 mm to be just under the diameter of the selector shaft.


Note the shortened 2.5 mm pilot drill (cut so that the chuck is a snug fit in the internal bush in the casing when the drill touches the case)

Method :
Remove selector assy from c160
dismantle c160 selector mechanism so you can detach the end cap and oil seal
pack gearbox with paper/rags below selector mechanism (to keep junk out of box), while leaving room for the drill bit and extension.
re-fit c160 end cap complete with oil seal.
Grease pilot bit heavily to catch metal shavings
Fit pilot drill bit in extension
Slide drill jig (bush) on extension
Slide the drill assy into the geabox through the end cap (jig/bush should be a snug fit in the oil seal)
Attach drill to extension and drill 2.5mm pilot hole

replace drill bit with (greased) 4.5mm bit and enlarge pilot hole

You should now have a nicely centered 4.5 mm pilot hole through the casing, where the selector shaft has to come out.

Remove drilling apparatus and c160 end cap.
Pack gearbox with rags, as the next step will generate a lot of aluminium shavings.

Turn geabox over, and carefully expand the hole to 19mm (3/4 ") with a step drill from outside the casing.
The oil seal carrier should now fit in the hole you have just made.

to be continued...

[AdrianS]

Now clean and scuff-up the surface of the gearbox where the oil seal carrier is to fit, and carefully clean out all the aluminium shavings from the step drill (I used compressed air, a shop vacuum, and thinners), while the box is still plugged with rags

Insert the c60 selector shaft (without any select levers or springs) in the case, and temporarily fit the end cap to locate it.

Dry-fit the seal carrier; it should fit in the 19mm hole you just drilled in the casing, without binding on the selector shaft.

When you are happy with the lineup, press the new oil seal into the carrier. It should protrude by about 5mm; this provides the lip the dust boot fits on.

Clean all surfaces to be glued with metho, and lightly scuff them with (clean) sandpaper, but leave the selector shaft slightly oily/greasy, so it can't bond to any overspill.

Now bond the oil seal carrier in place with JB weld; the oil seal will help center it on the selector shaft.



Leave to set for at least 24 hours.

nearly done...

[AdrianS]

When the glue has set, remove the end cap and selector shaft.

Assemble the hybrid selector mechanism (I re-used the c160 roll pins) :

Make sure the flat on the selector shaft is at the bottom (the same side as the shift levers)

Insert the new selector mechanism in the box, and fit the new end cap (I used gasket sealant and a dab of low-strength loctite)

Here is the assembled box, waiting for the JB weld to be sanded smooth :


That's as far as I have got.
All gears and reverse select nicely (with multigrips on the shaft).

Next : making a bracket for the cable mount (when I build it)

to be continued (in a week or two)

[senn]

omg rep to you for this! Lots of photos, and looks like you have taken your time explaining all the steps. Drop into AW11 anon and link to this, i'm sure some of the other boys will be interested in this conversion..

[GUN METAL]

excellent work Adrian, keen to see how it all pans out, do you have a gear chart handy for the c160 copared to the C52 ?

And what of the engine and use for the car......unless i missed something

[AdrianS]

These are the figures I am using (may be wrong )
taken from http://www.twincam.info/index.php?showtopic=33790

Box	1st	2nd	3rd	4th	5th	6th	Rev	Final
c50	3.545	1.904	1.310	0.969	0.815	n/a	???	3.722
c52	3.166	1.904	1.310	0.969	0.815	n/a	???	4.313
c60	3.166	2.050	1.481	1.166	0.916	0.725	3.25	4.529
c64	3.166	2.050	1.481	1.166	0.916	0.815	3.25	4.529
c160	3.166	2.050	1.481	1.166	0.916	0.725	3.25	4.529

Calculated speeds in kmh/1000 RPM
Wheel = 195 50 15
Dia = 576 mm 15" + 2x (50% of 195)

Box		1st	2nd	3rd	4th	5th	6th
c52		7.95	13.22	19.22	25.98	30.89	
c60/160	7.57	11.69	16.19	20.56	26.17	33.07
c64		7.57	11.69	16.19	20.56	26.17	29.41

Note how 5th in the six-speeds is close to 4th in the c52. The lotus (c64) box has a lower 6th gear, again quite close to 5th in the c52.

[AdrianS]

And what of the engine and use for the car......unless i missed something

I didn't mention it, as I didn't want to clutter up the thread, but it's a 20v blacktop. I bought a '99 JDM Trueno (AE111) BZR half-cut: blacktop, c160, helical lsd and big brakes all in one yummy package.
Should spuce-up my mk1a mr2 nicely. He's a daily driver, but will be doing some hillclimbs & track days once it is sorted.

[GUN METAL]

excellent, i just wanted to check it had a 20V or something that wanted to rev as i would imagine the 6 speed would be a bit pointless otherwise.

in the sacond chart on post 7 there is a format issue with the C160 being out s notch so its a bit confusing (at first). the ratios look good but i will be interested to see how it works out in the real world. I think the best part will be having the overdrive 6th........great for getting "to" the race track

excuse my ignorance but is the C 64 normally connected to a 2ZZ if its to do with the Lotus ?

finally hows the strength of the 160 compared to the 52 ?, not that i think you should have many dramas as i have seen 52 connected to some decent 4As, even up to 130 kw at the wheels (forced induction) in an Adub but you have to be gentle with them. all i am saying is i dont think i would be doing to many 8 grand clutch dumps at the start of your hillclimbs ........or going forced induction UNLESS the 160s are a fair bit tougher than the 52s

Sorry for all the interuptions to your technical thread its just that i know many aduubers would love the idea of the 6 speed but i think there are other factors involved with its final use / application.If you dont want this non installation related stuff in the thread for sake of ease of reading let me know and i will be happy to delete it.

[MR22ZZ]

C60 is on the Celica
C64 is on the Corolla and Lotus.

The C60 has the shifter linkage position in the same place as the AW11 C52 hence my want to get a celica 2ZZ package.

As for strength, a C series is a C series. They are not built to take heaps of HP, but I have seen a few 250kW cars still using C56, C60 and C64 and lasting quite well... though they do break eventually after 6-12 months.

[AdrianS]

.. i just wanted to check it had a 20V or something that wanted to rev as i would imagine the 6 speed would be a bit pointless otherwise.
...

Actually, the 6 speed would make a big difference for a 16v also, maybe more than for a 20v.

This table shows the revs in the next gear, when changing up at 7000 RPM

Box	2nd	3rd	4th	5th	6th
c52 	4210	4816	5178	5888
c160 	4533	5057	5511	5499	5540

note how with the c52, you need over 7000 RPM in 1st to be above the TVIS opening point (approx 4300 RPM) in 2nd.

[GUN METAL]

250 kw at the wheels with a C series, man you would have to be gentle with that !

Adrian, yep its all about power under the curve and shortening the difference between gear withg a peaky engine works well.

its interesting that going into 5th is worse but you probly wont be seeing that on a track much, let alone a hill climb.

appreciate your comments on the TVIS, ah the ole TVIS you dont need that or variable valve timing when you have forced induction (supercharger).............well its not as much of a requirment anyway when the torque curve looks like a billiard table

The other thing to note is when you launch an Adub you get instant traction, when you launch a Corolla (where the black top drive train came from) you will never have as much traction, hence clutch and CV and drive shafts etc wont see as much torque transfer.

Yuo might want to think at least about the clutch, then again maybe not, may make the gearbox last longer

[AdrianS]

Adrian, yep its all about power under the curve and shortening the difference between gear withg a peaky engine works well.

I started out just wanting to fit a c160 and keep the 16v, but the easiest way to get a c160 is to buy a half-cut (or so I told myself ): c160 boxes are neither common nor cheap, especially with the lsd.

The other thing to note is when you launch an Adub you get instant traction, when you launch a Corolla (where the black top drive train came from) you will never have as much traction, hence clutch and CV and drive shafts etc wont see as much torque transfer.

Yuo might want to think at least about the clutch, then again maybe not, may make the gearbox last longer

Good point.
I figure with the traction the aw11 has off the line, I'd rather slip the clutch a bit than try to wheelspin. Clutches are cheap compared to gearboxes.
The c160 has a lower diff than the c52, and the blacktop has better low-end torque, so it shouldn't be too much of a handicap.
I will enjoy learning to drive better/faster on the track; drag-strip starts are what keep gearbox rebuilders in business.
It's still only an n/a 1600 after all.

ps I appreciate people's comments, but I don't want to go into too much detail about my mr2, as this isn't the forum for general chit-chat. I have a build thread on MR2 Australia with more (too much ?) info, photos etc.
This thread is fine for things like clutch & driveline discussion (including not breaking the box off the line), as well as the swap how-to and any issues I come across in the conversion.
Please no-one take this as a criticism! I don't want to stifle discussion; this reminder is mainly aimed at myself, or I'll be off on a tangent in no time!

Back to the gearbox :
The donor BZR has equal-length driveshafts to minimise torque-steer; this requires an intermediate driveshaft, running back under/alongside the block, with a support bearing in a massive forged? bracket.
This intermediate shaft isn't needed in the aw11; the aw11 driveshafts fit straight into the diff. I believe I'll have to modify the alloy brace connecting the box to the block to clear the aw11 drive shaft; that will need to be documented.

I'm working out a gearchange chart for fun, using both Toyota's power figures and a dyno run I found for a blacktop corolla. I'll post it here when it's done.

no I won't.

[AdrianS]

Final steps before installation : mounting the pivot bracket to the c160, and fitting the gearbox-end mount to chassis.

To mount the pivot for the selector, we first re-drilled and tapped the small threaded hole on the box in front of the selector shaft, and fitted a threaded insert.
A mount was made which bolts to the insert, and snakes around to pick up a threaded hole on the other side of the casing. The mount has to curve to clear the speedo sender, and was shimmed to the correct height. The original c52 pivot bracket (with some modification to clear a bolt head) bolts to threaded holes in the new mount.





The c52 gearbox mounting plate has been re-worked to fit the c160 casing, while still using the stock aw11 rubber mount.



I apologise for the quality - gloss+flash=no detail.


Ready to go (except for some paint) :



The next step is gear selection - when installed !

[AdrianS]

ps no drawings or dimensions for the mounts - they were made in stages, tacked while on the box, then removed and welded properly. You can see some of our alignment marks on the back of the box.

[AdrianS]

Note - the flat on the c60 selector shaft positions the cable linkage approx 10 mm further out from the centre of the box. Until I fit the cables, I won't know if that's going to be a problem. If necessary, I'll modify the cable mount on the engine.

[AdrianS]

Update : the gearbox is in!
The chassis mount was within 1mm, and the aw11 shift cables mated perfectly. All 6 gears and reverse can be selected with no problems.
The c160/blactop combination has an alloy stiffener that joins the lower block to the gearbox. This needs to be ground away to clear the aw11 rhs drive shaft - I removed approx 8 mm of metal, but managed to do so without any issues.

A successful conclusion.
Thanks to Aaron Willis for help with part selection for the gearbox, and John Ellis for fabrication of mounts & brackets.

[AdrianS]

Final update (unless it breaks) : car is on the road, all gears select smoothly. Combined with the 20v blacktop, it's a very balanced package.

[chillii]

Excellent write up.

I just sent you a PM. How's the MR2 coming along? I'd be very interested to have a chat and a look at it one day if your free. I'm also in eastern suburbs of melb.