KE25 Diff/Brakes/Suspension
Current:...
Front : std ke25 strut/disk with kp61 Starlet hubs, 4x114.3mm stud pattern.
It's a bolt in swap. (ke25 studs are 4x110mm on NZ models). Front springs have 1-1/4 coils
cut out of em but are still captive with the standard shocks, this lowers the front
about 25mm.
Rear : Diff is from a '68 RT40 corona which is an 8bolt version. But apparently the 6.62" D series 10bolt diff will fit a 6.7" T series head. To make this diff fit, the leafs needed jacking out 20mm total to bolt onto the corona mounts (not good for the bushes). There's no shock mounts on the rt40 diff as the corona has them mounted on the leaf retaining plates, so new shock mounts need welding on top of the diff mount like the original ke25 diff. (i never got round to doing this). ke26 wagon has the bottom plate shock mount like the rt40 so would be an easier conversion in a ke26 wagon. RT80 era Corona diff is another option ie around 1370mm wide.
planning...
Diff:
I plan to use a shortened toyota 'F' series 7.5" live axle disk brake diff. These are pretty rare and found in jdm spec ra45, ta45, rt132 GT spec, and us spec ma45 seem to be the same. These have identical axle bearings as ae86 disk diff.. Another option is the ms110/ ms112 Crown which some models have
an internal drum handbrake and 260mm disk. The Crown diff are 5stud 5x114.3 so
the axles would need redrilling to the corolla 4stud. The locating ring on the
5stud version are also larger diameter so be wary as the std corolla or celica rwd rims will not
fit! The crown diff will require shortening too as they're pretty damn
wide! (1450mm) i've had one of these diffs fitted in my KE70 done early 2004 and had to
watch what rims used due to guard rub.. the ke70 has a wider chassis than
ke25 tho so will be worse. A 7.5" F series lsd diff head can be found in jdm cr30 masterace-surf and probably in the odd
liteace or estima emina? some ra28 celica.. but are pretty rare to find in live axle variation. IRS versions are found in GT spec jdm tt142, ta63, aa63, ra63 corona/celica/carina and ma61,
ma63 etc celica-supra's as they were optional from factory. Altezza torsen lsd and aftermarket LSD's for altezza also fit as they're 7.5" A01B etc.. some may need minor mods to the diff housing for clearance on the crown wheel retaining bolts or end of pinion shaft to the torsen housing depending on particular parts used. Toyota IRS diff internals
including the lsd can be swapped into a live axle diff head of same size. (there are some exceptions)
Driveshaft:
Will use a shortened shaft from something using same box and diff yolks.. should keep costs down by simply shortening a std shaft. May be an old corona shaft with W50 box and T series diff as these will match W55 and the F series diff pinion flange. (there are variations tho)
Front Struts:
Too many options and plans keep changing... ive yet to decide..
Setup #1 the lightest and simplest way apart from using original strut! is using ae85/ae86 strut (which is a common upgrade for te27 owners), sitting atop te21/te27/te28 steering arms (bolts in a ke2#) with short stroke shocks and ke25 top hat to bolt straight into the ke2# chassis.
The simplest option for vented disk is the std ae86 9" v disks/calipers/backing plates. But with an F series 7.5" diff with 10" disk's down the back, it
wouldn't be pukka for brake bias. so a 10" front disk and caliper upgrade would be in order. i'm favouring this option.
Setup #2 is to use ma45
mk1 celicaXX strut with 10" solid disks which will bolt onto te27/ae86 steering arms (can use ae86 p/s
arms 115mm C-2-C if te27 arms not available). The mx73 cressida 10" vented disk/hub do swap across to
these struts as the bearings are the same but the ma45 caliper is not wide enough to fit
around the wider cressida vented disks (tho maybe with worn pads). so a fabricated caliper mount
plate required to suit new caliper, ie 4-pot calipers could be used. This
should theoretically give me a bolt in 10" vented disk strut with decent
calipers (tho weighs more than option 1).
Setup #3 to use toyota 10" vented
disk/struts (ta63, cressida etc) but many geometry changes required to make work and they're not exactly light in weight. Best to use custom made steering arms as the
shortest factory arms available for the 90mm strut (that we can find) are 125mm between
centres (from power steer ta63 celica etc) compared to the ke25 arms at 110mm. Otherwise this set up would give an
increased turning circle and slower steering response with longer steering arms.
The downside of the larger struts is the added positive camber amongst other things so camber plates or longer lower arms etc would be required for ideal setup. Then the usual RCA's fitted when lowering the car substantially, short stroke shocks, urethane bushes throughout etc etc.
Steering:
Gimme rack and pinion! The mounts
for this can be welded onto the rear of the engine cross-member similar to an ae86.
This will also give me more steering component clearance under the 4age's sump than the std
recirculating-ball steering system and will have quicker lock-to-lock if the correct
rack steering ratio is found. Mods required would included modifying/adding universals to the bottom of the steering column (as used in fwd corolla's) since the rack input shaft would be in a
different location. This obviously is ALOT of work and careful planning is required
to make it work successfully. Most toyota racks measured so far
are all too wide. The ke2# inner tie rod pivots are about 100mm narrower than
most later model toyota's with racks. If i did use one of these later racks it'll affect the toe
as the suspension travels up and down (bump steer). So i'm looking for a rack the
correct width between the rack ends. Too little is known about steering/suspension geometry thus far so i'm in no hurry to feck it up! The other option is to widen the control arm
pivots which can be done using a modified ke3# engine crossmember and shorter lower arms which will allow a wider rack than needed with the ke2# engine crossmember. hmm major surgery!
Brakes: lookin at using 10" vented disks on front and 10" disks
on the rear. the downside is some 13" rims will no longer fit. I'm trying
to find more information on the jap spec rhd te27 pedal box, brake master cylinder, brake
booster and hydraulic clutch -as these are rare-as-rocking-horse-shit in NZ.
(any info much appreciated!) Im thinking i'll eventually be forced to fabricate a custom pedal box to shift the brake
master cylinder closer to the strut tower as found in a rhd te27. This will give me
room to fit a longer (later model) twin brake master cylinder and brake booster if i need one.
After a study of a jdm te27 and the NZ ke25, the brake master mounting holes are in
totally different positions. The ke25 does not have any markings to remount in the
jap te27 positions. A different brake bias valve will need to be fitted to balance
front/rear brake bias etc.
General suspension upgrades:
Will use Nolathane bushes all round. Use strut bar on the front to lessen
chassis twist.. possibly upgrade the front sway bar but do this once the rest
of the suspension is finished. The 7.5" diff has a sway bar mount
already so will mount up a rear swaybar by adding some end links to the ke25
undercarriage. (std ke25's don't have a rear
swaybar). To lower the rear I have sourced some reset leaf springs which are
better (to reduce axle tramping) than using lowering blocks. I'll then play with
adding/removing leaves to stiffen the spring rate. I'd
like to also add some tramp bars because axle tramp (wheel judder) is a problem.
Wheels: Always keeping eye out for Jap oldschool 14x7 or 15x7 deep dish
alloys. Was using 13x7 cheviot hotwires and now scored some 13x7 mega dish
8-spoke Performance Superlites (Panasport or Watanabe look-a-likes). Bought some Konig Rewind 15x7 for it too =)