Hi Scotty,
First off, thank you for doing what you do. I have a 1979 Plymouth Fire Arrow I am trying to keep on the road (it has about 58,000 miles on it!) One of the more challenging parts of the car is that it was the only model that came with rear disc brakes (all others had drums), and the rotors are very hard to find. I have been warned that machining rotors that are close in size is not a good idea, and that I should change the rear brakes to similar ones from another car that would be more common.
Is the warning correct? If it is can you suggest a donor vehicle or someone to contact the figure out what it would be?
Thanks in advance,
Richard
Is the warning correct?
Yes. There should be a minimum thickness specification cast into the rotor. The rotors can be machined as long as the resulting thickness meets or exceeds that spec.
For the Plymouth Arrow 2.6 rockauto.com shows front and rear rotors to be the same but different left and right. This may or may not be correct:
They show the rotors as fitting the following vehicles:
As you are probably aware that is actually a rebadged Mitsubishi (the Hyundai Pony, sold in Canada, was also heavily Mitsubishi-based), so chances are that period Mitsubishi rotors would also cross over.
If there is a club or site devoted to 1970s Mitsubishis and vehicles based on that that would probably be your best bet.
Yeah but I'd consider what @chucktobias said about having somebody check the thickness of your rotors.
There may be enough "meat" left on them to have them cleaned up.
And like Chuck says, that may be the solution here instead of sourcing replacement rotors (depending on how badly they're scarred)
Rotors on cars of that vintage are usually more integral to the car itself, as opposed to bolt-on bolt-off rotors of today. I have a 1979 Pontiac Catalina with front discs. The wheel bearings are inside the inner part of the rotor, on the spindle, rather than being a separate component. They typically have a lot more "meat" than rotors nowadays, as a result.
Only you can make that decision, though since we don't know the condition of the rotors. If you have a maintenance manual, it'll probably say in there as to whether or not there's enough metal left after shaving the bad stuff off. Providing there is enough, it should be fine.
Hi Chuck,
Only the Fire Arrow had rear discs, the Celeste, the Lancer, and the other Arrows all ran rear drums. Also, the rotor vary front to back, not left to right so I suspect there is something wrong is the listing. I regularly find problems with parts for the vehicle, sometimes parts from the Plymouth Arrow truck are confused for parts for the car too.
The Old Colts club is the only web site I am aware of that was for 79's era Mitsu's and that site went dark a year or so ago.
Not certain if anyone can confirm or deny this, but I recall a mechanic once saying the brakes looked similar to those in the similar era Dodge Daytona. Right now I am getting rotors for a mid eighties Corolla machined for the Arrow but have been told that is not a good solution as the brakes might nor be properly balanced after that.
I appreciate any and all feedback.
Richard
Unfortunately it can be tough to source parts for a a low-production 45-year-old import or to even find correct listings for them. If the Corolla rotors can be machined that might be the best solution if they work properly. Even on some old low-production American cars with early disc brake systems the best approach is to adapt newer, more common parts.
So I am getting the existing rotors machined and am now figuring I should be on the hunt for rotors to have in case / when these give up the ghost. The corolla rotors are not in stock either it seems so I either wait for a third party to make rotors for the car (R1 Concepts keeps promising they will do this on their site), or, find someone who makes rotors. If anyone is aware of someone that does that please let me know. Or if someone has another possible solution I am all ears. Thanks!
Richard