Rear disk brakes installed on my I-mark RS

[Luc]

I have finally decided to get my I-mark back in shape to use as a daily driver. Instead of spending a bunch of money for new drum brakes, I've decided to use the spare disk brakes I picked up from an Impulse XS and do the conversion.
Thread Editing in progress...

Removing the rear subframe
1) Disconnect brake lines from rear brakes and drain.
2) Disconnect rubber brake lines from rear subframe
3) Completely remove brake drums and hubs
4) disconnect shocks from subframe (requires jack under subframe to
compress shocks)
5) Remove springs (they fell out for me)
6) Disconnect subframe from car (two hinge bolts)

Installing the disk brakes
Parts I'm using from an Impulse XS:
dust shields/caliper brackets
hubs
calipers
fluid lines (short length attached to calipers)
e-brake cables

The four-bolt pattern on the subframe plate is smaller than the bolt pattern on the hub.
Slot the holes to match the hub(Pic 1,2). Although the new holes are closer to the edge of the mounting plate, my mechanic felt that no extra reenforcement was needed.

Pic 1


Pic 2



Normally, the caliper is mounted toward the front of the car. Initial test fittings had too much interference with the springs and the subframe itself.
However, rotating the dust shield 180 degrees, swapping the calipers, and installing them on the back of the disk leaves plenty of clearance.

The caliper bracket attached to the dust shield needed to be ground down to sit flush against the mounting plate. Additional grinding on the subframe also helped clearance. (see pics 1,2, and 3)

Pic 3


Install the caliper assembly on the dust shield, slide the rotor onto the hub, and then install the rotor/hub and dust shield onto the subframe mounting plate(Pics 4,5,6,7). An extra set of hands really helps this procedure.

Pic 4


Pic 5


Pic 6


Pic 7


One of the bottom hub bolts is very close to the subframe wall and will either need to have a small head or the subframe will need to be grinded.

The subframe needs some grinding to make room for the lower caliper bolt on the dust cover bracket. As can be seen in Pic 8, once assembled, and without access to this bolt, the entire hub assembly must be removed to remove the rotor. Perhaps the subframe could be cut out to allow a socket in, but reenforcement may be needed as a result.

Pic 8


Edit:
After Jeremy(Zimahype) stopped by to give me a hand with this project, he felt it would be less of a hassle in the future if I went ahead and made that lower bolt accessible. So, one $30 grinder later, voila! (Pic 9,10)

Pic 9


Pic 10



Pic 11



The existing brake line on the caliper will need to either be connected to existing hard line on the subframe or the soft line on the car, or a whole new line made (haven't decided)

Pic 12


The e-brake cables attached to the calipers don't match the existing setup on the I-mark. I'm going to hopefully attach the caliper cables to the single line that goes to the e-brake handle.

Pic 13


Pic 14


Pic 15


Pic 16


Any suggestions and/or comments are welcome.

Additional repair activities on this car:
Brand new fuel pump, strainer, fuel level sending unit, and fuel tank ordered
Fuel filter
Swap in spare tranny
Repair driver's seat (middle sags to the floor)
New rear tires

On another note, does anyone know why the 89 I-mark RS has 5 less hp than the 91 Storm? They both have the same engine (albeit with different heads)

[talontsi97]

Sounds good, something i plan on doing in the future as well so keep us updated on the whole project. Get some pics up if you can to. thanks and good luck

[Lakeshow23]

Originally Posted by Luc

On another note, does anyone know why the 89 I-mark RS has less hp than the 91 Storm? They both have the same engine (albeit with different heads)

Even if the Storm develops more power, I'd bet my wallet that the '89 I-Mark RS spanks any '90 or '91 GSi in a drag. '89 IMark RS' are just flat out difficult cars to keep up with.

[steve wakely]

i thought the iMarks had 130 hp and the storms had 125. because of the cams and ignition timing. the intake manifold is slightly different aswell.

[omar]

This thread is worthless without pics






MOD EDIT: Do it right!

[venomous]

I kinda forgot about Luc.

[Luc]

I kinda forgot about Luc.

That's been my secret evil plan all along!

Actually, my car projects got sidelined for a while. Been surfing in most of my spare time.
At any rate, my primary goal for 2008 is to pay off some debt. I need the I-mark back running as a daily driver so I can sell my truck and get rid of the monthly payment.
I'll figure out the issues with the Impulse RS as soon as the I-mark is done(should be ready by next weekend).

Pics and more comments are up top.

[omar]

The existing brake line on the caliper will need to either be connected to existing hard line on the subframe or the soft line on the car, or a whole new line made (haven't decided)

Pic 10



I know that this little project has already run a bit over budget, but I would have a new line made just so that I know it will all work properly and without problems down the line.

On a side note you should install the nitrous kit from your impulse onto this car and have some real fun on your drive to work

[Racer_Jim]

Looks good Luc!
Maybe we'll both get Isuzu's running in '08

[Luc]

Thread updated with more pics.

Brakes and subframe are reinstalled.
Unfortunately, a slide bolt on each caliper is frozen and won't come out. I'm bringing them to my machinist to see what he can do. Hopefully he can extract the bolts and I can clean up the holes and buy new bolts(I bent them trying to get them out).

I'm going to have a local hose company make me some brake lines.
That leaves some experimentation with the e-brake setup.

Jeremy and I also started on the swap to larger disk brakes on the front of the I-mark. The project ended tonight when I couldn't find a 12mm drill bit to bore out the caliper mounting holes.

Stay tuned!

[Eddie Z]

Nice project. Looks great!

[Aamir_bt]

this thread is awesome!

+1 for the brake conversion!


EDIT: +2 for Malachi's suggestion.

[malachi]

Sticky status IMO. Now that the pics are up.

[Luc]

Borrowed a 15/32 drill bit from Jeremy and drilled out the front I-mark spindles tonight. Pretty easy to do when you keep a steady stream of lube on it.
Unfortunately, the new Impulse rotors appear to touch the Impulse caliper mounting bracket when installed. I've never seen anything mentioned about this from those who have done the mod (Munk, Chris, etc). What's going on here?

[malachi]

Can you add a washer on each lug? As a spacer? I would even consider welding the washer in place. That should bump it out enough to make it all work fine.

Also, it looks like your using a double wall rotor, but arn't all Impulse rear rotors single disk? That woule make them much thinner and not touch.