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Looks like I have a bent axle. Purchased and installed a used disc rear end, and test drive revealed chirping thweepthweepthweep noise left rear that goes away when brake applied or ebrake pulled. Measured throwout at 0.036” at flange and 0.059” at rotor. Manual says max 0.0039” so appears waaaaay out of spec.
Concerned about buying used as don’t want another one that arrives bent. Anyone know of a source of new OEM or remanufactured?
Those sure are purty. But good god $700! Totally believe that’s a reasonable price given what it takes to make them… but having a hard time getting used to that amount of dollars.
I don't know anyone that has off-the-shelf axles. Moser can make them though. If you go this route and want other than factory wheels size (4x110) now would be the time to get something different.
In my digging around I discovered rotor shims. Would I be inviting disaster if I tried to stack up enough shims to cure a runout of .059” at rotor edge?
If the axle shaft is bent, it would make sense to see some runout on the face of the flange. Brake rotors can warp so checking the runout from the rotor face could give you a compounded or exaggerated reading. Plus, the further away from the center of rotation you check, the greater the deviation will be. This might help explain the .023 difference between your readings from the axel flange and brake rotor. Did the high and low spots correspond or were they different?
Unless I'm missing something, not sure how using a flat shim would alter or change the amount of runout.
Are you sure the axle's bent? Have you ruled out anything else making noise? It could be the brake backing plate or caliper hardware contacting the disk.
The manual doesn't show anything about checking runout on the axle, just for checking the brake disk.
It does show checking a bent axle by measuring in the middle of the half-shaft:
Yes, high spots positions match between flange measurement and rotor measurement. I also rotated the rotor 180 degrees and the high spot stayed in the same place rather than following the rotor…. Telling me rotor is straight but flange is not. For sh*ts and giggles turned the gauge 90 degrees and measured if the flange was moving up and down as well as in and out. It did, and in a way that also matches what the flange would do if axle were bent.
The rotor shims have a taper…. From what I can find out usually around .006” difference one side to the other. So I would need to stack up 10 of them! Gonna give Panic an order tomorrow for axles. None of this makes financial sense, but neither does owning a rotary.
Are you sure the axle's bent? Have you ruled out anything else making noise? It could be the brake backing plate or caliper hardware contacting the disk.
The manual doesn't show anything about checking runout on the axle, just for checking the brake disk.
It does show checking a bent axle by measuring in the middle of the half-shaft:
Would love it NOT to be the axle. But flange is definitely showing 10x the maximum runout given in the manual. And when I spin the hub and check carefully there is clearance between anything on the brake or hardware and the rotor.
Thought of another way to check. I am going to swap the axles left to right and see if the noise follows the axle or stays with the caliper. Will report what I find.
Since you are removing them to do the LR swap, you could roll them, even on a couple of saw horses...1/16" of an inch is a lot and you should be able to see the wobble, I'd think.
Hard luck on that used part. I've been quietly enjoying your posts and progress. You've got a really nice car there, all of the good work you've put into it.
If you remove the axles, it will provide the chance to check them between centers as the illustration depicts. Would be interesting to see how the runout in the middle compares to the published service limit of .059.
A machine shop with a press and a couple of V-blocks should able to straighten them. Or, possibly chuck and steady rest off the bearing surfaces and skin cut the flange face to true it back up again.
Decided to take the Bay Area approach and just throw some money at it. Panic axles on the way.
No matter how much I overthought it and tried to find reasons to dismiss what I was seeing, there is no getting around the the fact that the surface of the axle flange has a wobble to it. And when I look at FSM specs and Google searches, that wobble is well over 10x the amount considered workable.
Was just feeling twitchy as project scope had already grown to include new rotors, driveshaft and proportioning valve. I have the cash saved up, so just need to let it go.
Oh, and seller of axle assembly I believe is blameless. He is trustworthy and I am sure did not know of the flange issue. One of those learning the hard way experiences for me…. If I ever have to buy something like this again I would take me rotary dial with me!
Yeah these old cars are always full of "learning moments" and sanity tests... Sounds like you are doing it right.
A GSL rear I bought many years ago had the same issue - notable wobble and chirpy brakes from excess runout on the axles. This was back when stock replacements were easy to find and cheap. Not so much anymore. I will be curious to see how those Panic axles are as it's nice to just have a "click to buy" solution as opposed to Moser where you have to specify everything (even though they have made them a bunch of times previously - hell I have a set!).
Ordered a set from Panic during their Black Friday sale. Matt is hands down the best correspondence I’ve had for a sale. I shot him a email with some questions and his response was well past business hours. Matt even discussed the limits of the axles. Says the were rated in the “200-300 hp range” The axles are a 1541h alloy. Which if sources are to be believed, will be 30-50% stronger than stock.
the funny thing that I thought was odd is how does a small Toyota shop out of Oregon have the facilities to produce this product. Well, they don’t. Panic Made’s axles are Dutchman Axles. Which seem well regarded in the 4x4 and drag racing circles. I did weigh the axles to compare and the weight is the same between oem and panic/dutchman. I did consider Moser I chose to pay the premium for that one click solution. Overall, I’m quite happy thus far. Now to get a new LSD .
Yes, high spots positions match between flange measurement and rotor measurement. I also rotated the rotor 180 degrees and the high spot stayed in the same place rather than following the rotor…. Telling me rotor is straight but flange is not. For sh*ts and giggles turned the gauge 90 degrees and measured if the flange was moving up and down as well as in and out. It did, and in a way that also matches what the flange would do if axle were bent.
The rotor shims have a taper…. From what I can find out usually around .006” difference one side to the other. So I would need to stack up 10 of them! Gonna give Panic an order tomorrow for axles. None of this makes financial sense, but neither does owning a rotary.
The phrase "project creep" is familiar to most folks who own first gen RX7's, I enjoy reading about the projects you take on, and find your "tenacity," and "attention to detail," refreshing Slow_sevens!
The phrase "project creep" is familiar to most folks who own first gen RX7's, I enjoy reading about the projects you take on, and find your "tenacity," and "attention to detail," refreshing Slow_sevens!
Quite honestly I am glad for project creep. I retired early a couple of years ago and have a deep dread of waking up one morning and having nothing to work on.
Only downside on the Panic axles is they are soooo pretty that it seems a shame to hide them behind disc rotors.
I am fortunate in that I bought my 85 GSL-SE thirty years ago in Ventura, CA, from the original owner with 53k on the odometer, and it was the end of the first generation. Which means fuel injection, four wheel disc brakes, and a larger LSD rear-end which made my life much easier, and while parts have always been pricey, they were available back then. You need to be resourceful, skilled, patient, and willing to ask for help to take a survivor and do what you are doing ( independently wealthy helps too) while I however, am a 71 y/o retired Navy man shoveling snow in minus 8 degrees with twenty-knot winds and my RX7 is tucked away. The Bay area works for me, keep up the good work! Taking the winter off.
Figured I'd post this here. I reached out to Panic to see if he is able to do the GSL-SE axles with 5x114.3 or even better with both 4x114.3 and 5x114.3 to give us the option to use FC 5 lug parts. As Richard said above his correspondence was excellent - very timely and he uses actual sentences and punctuation, which seems rare these days.
The good news is that yes, he is able to make a dual pattern axle (again this would only be on the GSL-SE length since the flange size on the GSL version is too small to safely drill a larger pattern into) and the price would still be the same! Granted it is expensive, but the option to do this without a bunch of back and forth with Moser is worth it in my opinion. Plus you are supporting a small shop - always nice.
Anyway, I am not buying these right now as the Moser's I got from Re-speed backin 2007 are still going strong, but I just wanted to let everyone know that there is an "off the shelf" option for 5 lug on the stock rear axle. Hope that helps someone
Panic axles arrived. Stud holes are not threaded. Was there any other way that studs attach on 1st gens? Is it standard to receive axles unthreaded and cut threads yourself? Got a message in with Panic asking, but wanted to make sure I wasn’t being dumb.
Studs will have a knurled end and need to be pressed in. Panic should be able to tell you what size you need.
I thought GSL-SE studs were as well, at least I remember pressing them out.
Origins axles I removed had threaded holes for the studs, and picture of axle on Panic website has threads. Maybe I have a weird setup and the pic on the Panic website is generic?
The 12A uses lug bolts where the GSL-SE uses studs.
Just heard back from Panic. They were super responsive and owned the mistake immediately. Holes should have been threaded.
I have already pressed bearings and installed axles. Would a workaround be to press in some studs? If so, can you press studs without a hydraulic press?
01-15-24, 04:18 PM
