Isuzu Rear Discs
Cliff
Have just finished this project for my GT (and for a Colorado Buddy too)
Charles Goin has written an excellent article about this as well.
There are two types of Isuzu Inpulse rear discs:
1) the 266mm diameter ventilated rotors that really need bigger ventilated discs on the front as well to be a balanced system.
They donot fit inside standard (or mag) 13" wheels so larger 14" or bigger are needed.
2) the 239mm (9.5") solid discs that are the same diameter as the standard GT front rotors and will fit inside 13" wheels.
I used the 2nd type making up an adaptor plate to mount the caliper which also has to have a recess machined to fit over the wheel bearing. The bearing MUST be clamped in by the plate as this is all that stops any end play and prevents the bearing from spinning in the axle housing.
The Isuzu caliper brackets can be made to fit too by redrilling the axle mounting holes - then an adaptor does not need to be made but it is not as "nice" since welding and redrilling is required.
(Just a toolmaker talking, Charles! - my appologies)
It also needs a hybrid handbrake cable to be made and a bit of ingenuity to get the brake lines to conect up - though the Isuzu brake line nuts are the same thread - on mine anyway.
This all works very well and give a good upgrade for the old drums.
An adjustable proportioning valve to balance front/rear braking and some modifications inside the master cylinder will also be required to complete the job.
When sourcing the discs just check that the Isuzu diff has a LSD or not - some do and they fit in the GT 1970 on diff along with the 3.90:1 gears. Also the front bakes are worth a look too. Nice wee 16mm thich ventilated rotors and the hub fits onto the GT front stub axle. Haven't investigated the caliper mounting probem yet but they dDO NOT just bolt on. I am trying to see if the whole Isuzu spindle will bolt in to the GT front suspension .....
Cliff
Have just finished this project for my GT (and for a Colorado Buddy too)
Charles Goin has written an excellent article about this as well.
There are two types of Isuzu Inpulse rear discs:
1) the 266mm diameter ventilated rotors that really need bigger ventilated discs on the front as well to be a balanced system.
They donot fit inside standard (or mag) 13" wheels so larger 14" or bigger are needed.
2) the 239mm (9.5") solid discs that are the same diameter as the standard GT front rotors and will fit inside 13" wheels.
I used the 2nd type making up an adaptor plate to mount the caliper which also has to have a recess machined to fit over the wheel bearing. The bearing MUST be clamped in by the plate as this is all that stops any end play and prevents the bearing from spinning in the axle housing.
The Isuzu caliper brackets can be made to fit too by redrilling the axle mounting holes - then an adaptor does not need to be made but it is not as "nice" since welding and redrilling is required.
(Just a toolmaker talking, Charles! - my appologies)
It also needs a hybrid handbrake cable to be made and a bit of ingenuity to get the brake lines to conect up - though the Isuzu brake line nuts are the same thread - on mine anyway.
This all works very well and give a good upgrade for the old drums.
An adjustable proportioning valve to balance front/rear braking and some modifications inside the master cylinder will also be required to complete the job.
When sourcing the discs just check that the Isuzu diff has a LSD or not - some do and they fit in the GT 1970 on diff along with the 3.90:1 gears. Also the front bakes are worth a look too. Nice wee 16mm thich ventilated rotors and the hub fits onto the GT front stub axle. Haven't investigated the caliper mounting probem yet but they dDO NOT just bolt on. I am trying to see if the whole Isuzu spindle will bolt in to the GT front suspension .....