MA70 7MGTE CPS Rebuild

Brent here of Concept Auto Ind

Doing a walk/talk through of a CPS Digital Hall effect sensor upgrade with a bearing & oil seal replacement for good measure on this client’s MA70 Supra currently receiving a host of upgrades from us. (The parts used in this kit are offered by ‘Driftmotion’ over in the USA)

First thing after removing the CPS unit from the motor, MEASURE the shaft depth exiting the housing will ensure the correct dimensions are maintained when reinserting the shaft upon reinsertion.

…onto disassembly.

Remove the plastic inspection cover revealing the inner pair of OEM sensors. A host of phillips-head screws secure original sensors inside the housing, all these including sensors & wiring can be removed and set aside.

Now is where access is granted to service/rebuild the CPS shaft bearing & oil seal. Being 35+ years old with a seal unlikely in shape and the shaft’s bearing having seen the same amount of revolutions as the motor, this is an easy option to perform.

Now disassembling the CPS unit:

I secured the drive gear in between a pair of wooden blocks in a vice to keep the teeth safe whilst drilling out the pin securing gear drive to the shaft – take care to drill straight through & not oval the pin bore! Some hammer taps on the shaft to separate the shaft out of the gear drive piece & set aside.

Then inverting the CPS Housing and hammer driving the shaft (from gear drive end) completely out of the bearing and removing it from CPS housing.

The shaft is solid and forgiving & should move with medium strike force but the pickups (opposite end) are precision machined so keep them out of range of damage.

With the shaft removed, linishing the shaft with a scotchpad (or similar) to remove the years of grime and muck built up followed by a light grease and set aside ready for reinsertion.

Now I did not have a small enough bearing remover or suitable tool to fit the inner shaft diameter, so I drilled and destroyed the ball-bearing carriers between the inner & outer races and was left with only the outer race which was large enough to install a pilot bush tool and removed.

Next was the oil seal that sits below the bearing, it is a miniature oil seal like any cam,crank, rear main etc.

Again not having a thin enough extraction tool as the shaft diameter, I carefully collapsed the old unit by destructive force and bit by bit, managed to leverage out the seal’s remnants & finally the outer metal shell.

Next was drilling the secondary hole through the original housing for the new hall effect sensor to meet the OEM pickup. Mount the new Billet Top housing to the Toyota case, scribe the hole to be drilled & remove top housing.

Pilot hole, drill up to size. Refit housing check sensor installs cleanly through both cases.

With all the tooling & modifying work done, next is time to clean the assembly.

I threw this in an ultrasonic bath with some light degreaser & ready to reassemble.

Starts with installing the new oil seal into the housing with a suitable drift or the exact right size socket works well for getting the seal home down into the bore.

Then the new shaft bearing into the housing, again a suitable drift till bottom out.

Then the shaft with machined pickups, be careful if swinging a hammer to not deform the pickups. It should not need too much force but using a press will make it easier to achieve the original shaft depth with precision. The shaft will have wear markings but they are virtually impossible to see once installed – pre measuring the setup is easier.

Reinsert the drive gear back onto the end of the shaft, install the new supplied gudgeon pin, install the new rubber seal onto the neck of housing where it inserts through the cylinder head and that is CPS assembly rebuild complete…onto the upgrades!

Install the new billet top cover with its inspection panel removed. Insert the rear sensor lower nut into housing, load the rear sensor through the 2 housings and land it on its nut.

Now I found the nut locks against the inner housing so rotating the sensor into housing (careful not to damage the premade wiring for both sensors) until the desired clearance is achieved, I went for a “loose“ .6mm gap between the teeth and sensor pickup.

When I was happy with sensor depth, did the final tighten on the upper nut locking the sensor in place.

The front sensor was a little easier, it has a knurled lower nut and is easier to access but same methodology ensues – load the knurled nut inside CPS housing & then sensor. With the first sensor fitted, you cannot rotate the second sensor since their wiring is spliced together but the knurled nut makes it easy to achieve appropriate depth, again feeler gauge for clearance on the upper most tip on the outer pickup and lock off the sensor’s upper nut.

Rotate by hand and check clearance.

Mount the 4 pin sensor plug onto the housing in OEM position with supplied new machine screw and reinstall onto the cylinder head.

*BIG NOTE* – OEM ecu will not support the new hall effect sensor signal and sensor &/or ECU damage will occur if not rewired & coupled with an appropriate engine management upgrade.

In this case, the vehicle received a Haltech S3 standalone with a new bespoke loom (with a host of other upgrades also) and was wired & calibrated appropriately for the new Crank & Cam 

Trigger setup.