Fitting a Collins T3 actuator

contributed by Alex Woolley
My standard T2 actuator wouldn’t hold 18 psi very well; this was shown up mainly on rolling roads when the boost dropped off to as low as 15 psi so I decided to buy a stronger T3 type.


I managed to find a Collins actuator very cheaply on eBay so I set about fitting it. To fit them you need to either but a new modified bracket (£15+VAT from KTR) or modify the standard one, I decided to modify the standard one. You will also need to run the ‘cup mod’ boost circuit. You may need a different wastegate adjuster but I didn’t (£25+VAT from KTR)

1, Take off the old actuator together with the bracket which is spot welded to it. It’s held on with several bolts on the compressor housing. If you have a heat shield on the turbo this will need to be removed. Take the actuator arm off the wastegate pivot, this is held on by a small circlip also remove the actuator hose.

2, Once off drill the three spot welds that hold the bracket to the actuator (be very careful if you want to keep the old actuator)! Elongate the bottom hole as shown in picture and also drill another larger hole between the 2 top holes.

3, Remove the 2 small studs on the T3 actuator and replace them with longer ones (otherwise it will foul the compressor housing)

4, Fit the bracket to the compressor housing and slide the actuator studs through the elongated holes of the bracket. Attach it by using nuts and washers on the studs giving just enough room that the actuator clears the compressor housing. See picture.

5, Fit the wastegate rod over the pivot adjusting it as necessary (I used the old T2 adjusting arm as it fitted o.k) Make sure you refit the circlip. Refit the actuator hose and make a final check everything is secured properly.

6, Take the car out and check it’s making the correct boost you want, if it’s not slacken the 2 nuts (see picture) and pull the actuator towards the front of the car (this will require effort)! And tighten the nuts in the process. If it’s making too much boost move the actuator the other way to reduce it’s preload or buy a lower rated spring which are available from Collins.