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I'm the original owner of a '90 RX7 GXL that I bought new in April 1990. So, last month was its 29th anniversary. I've never owned a car this long before. As of this afternoon, I've put 364500 miles on the car.
During March 1995, I replaced the original driveshaft with a replacement Mazda driveshaft at 91875 miles. During October 2001, I again replaced that driveshaft with another replacement Mazda driveshaft at 204533 miles. The lifespan of that second replacement driveshaft was 112658 miles. Using the above data, the average replacement lifespan based on my two replacement driveshafts was about 102k miles per shaft.
Back in May 2011, I bought a replacement driveshaft from Mazdatrix. This was one of Mazdatrix's (p/n 2691-704) driveshafts with the replaceable u-joints. It's sitting in my climate controlled storage bin still in the original box. Back in May 2011, I had about 284k miles on the car or about 80k miles on the driveshaft at that time. I was expecting that driveshaft to fail, like the first two did, within the next 10k to 20k miles or so. As of today, I'm still running the last driveshaft that I installed. It's now 18 years old and has seen nearly 160k miles of usage. Is seems odd that I got about 102k average miles of usage out of my first two driveshafts, but this last one has seen about 160k miles of usage so far. Is this last data point an outlier or what?
I think my current driveshaft is living on borrowed time. Actually, I'm getting a slight vibration, which may be due to the driveshaft. Usually, the grease in those u-joints starts drying out at some point. So, I think I'm going to replace it sometime next week since I need to drop the exhaust to replace my Bonez converter which is now over 14 years old. My thinking is that I don't want to get stranded hundreds of miles from my house when my driveshaft finally decides to crap out.
What are you folks experience with driveshaft lifespans on these cars?
I'll add my single data point. '89T2, chassis has 168,xxx miles on it now with the original driveshaft as far as I know. Purchased the car in 1999 with about 87K on it; drive shaft shows no evidence of ever being replaced, it still seems fine - no clunks, or unusual noises or vibration that would prompt me to replace anything. Usually when drive shafts begin to fail, there will be some warning - drive line vibration, noise or clunking as the U-joints wear out.
Ok, 168k miles is a respectable lifespan. Yeah, when my first two DS's failed, I experienced severe vibrations due to bad u-joints. With the DS that's in the car now, I get intermittent vibrations especially at higher speeds when under power. If I take my foot off the gas, than it goes away. I also get very low frequency squeaking noise when car is rolling at low speed with clutch disengaged. Sort of sounds like a dragging rear brake, but I changed brake pads, calipers and rotors on all four corners late last year.
'89TII original driveshaft replaced at 148,000 miles back in 2002, now only 52k miles on the new shaft so no problems..
Did have a vibration problem in 2008, thought it was in the drive-train, but everything I checked looked fine, drove me nuts as at times no problems, then it would come back. Long story short had a broken motor mount.
Here's one for ya. Original rotors/suspension/exhaust still on the car.
'89TII original driveshaft replaced at 148,000 miles back in 2002, now only 52k miles on the new shaft so no problems..
Did have a vibration problem in 2008, thought it was in the drive-train, but everything I checked looked fine, drove me nuts as at times no problems, then it would come back. Long story short had a broken motor mount.
Here's one for ya. Original rotors/suspension/exhaust still on the car.
Apparently, the TII's have larger and probably more robust u-joints. Therefore, probably not a fair comparison to the NA driveshaft.
I replaced my motor mounts last month after nearly 190k miles of service. The right mount was broken. That is, the rubber puck was partially de-laminated from the metal base. This was the second time that I replaced my motor mounts and I noticed the same problem with the right mount both times. Apparently, the right mount on these cars has a tendency to fail due its proximity to the hot exhaust manifold. Replacing the mounts cleared up a lot of my vibration problems, but not all of them. Within the past year or two, I replaced my transmission side mounts, cross-member, motor mounts, tie rods (both inner and outer), ball joints, half-shafts, wheel bearings and front suspension bushings. With each of these replacements, the car would drive much better and with less vibration, but I still notice a slight vibration. I don't know what's causing it other than the driveshaft. Maybe the rear end bushings? After searching the web, I read an article that said the average lifetime of rubber bushings on a car is 5-7 years.
Regarding the engine, my original engine met its demise at 211k miles in Feb 2002. That was due to a defective E-shaft thermo pellet oil bypass valve. The valve was stuck closed preventing the full flow of oil to the rotors for cooling. Mazda had a TSB on this oil bypass valve. I replaced it with one of these: https://www.atkinsrotary.com/store/8...let-ARE50.html. This is something that every FC owner should do.
I'm surprised that you still have your original exhaust. Your TII must be a garage queen? I've found the the original FC exhaust system has an average lifetime of almost exactly 4 years.
Yea, car in garage since new and in the last 28 years, never in rain, and has never been in snow.
Right motor mount severed, so tried comp motor/trans mounts, but removed the comp trans mounts after 2 days, too much vibration at idle.
Sounds like a guy that I used to work with. He is the original owner of an '87 TII that's also a garage queen since it has never seen neither rain nor snow.
It's old news, maybe 31 years old, had an '88 TII we purchased new, but Mazda bought it back because of the known problem with the trailing plugs not firing along with the high temps in the fuel tank causing an unbearable fuel odor in hot weather. They changed the position of the trailing plugs on the S5 and with the buyback, I purchased the '89 at dealer's cost.
Just an update. I replaced my driveshaft and high-flow cat last week. I replaced my Mazda driveshaft with a Powertrain Industries (p/n 2691-704) driveshaft . This is the same driveshaft that Mazdatrix sells. I thought that my rear u-joint was the problem, but apparently it was the front u-joint. I did a quick inspection and the front u-joint seemed very loose and notchy, but I didn't noticed any discernible play. It might have been that one of the bearing caps were on its way out. When i pulled the old shaft out, the rubber part of the tail shaft oil seal came out with it. Upon test drive, I no longer hear the slow speed squeaking that I did with the old shaft. It also appears that most of my speed dependent vibrations have cleared up.
I also replaced my 15 year old Bonez Superflo system (https://www.rx7.com/store/rx7/superflo.html) with a new one last week. The old system was rusting and had seen better days. The old monolithic cat was also partially clogged upon inspection. Over the last 20 years, this was my 3rd Bonez Superflo system on my car. I was expecting an uneventful install, but on the contrary had problems with this install. The pre-silencer is hitting the transmission cross member. I'm getting vibration in the cabin on idle and during acceleration. Also, my whole RB cat back exhaust system is way off center as you can see in the photo below. I replaced all 10 rubber muffler/exhaust hangers too.
Apparently, this Bonez Superflo system wasn't manufactured to the same specs as my first two Bonez systems. I sent rx7.com an email last Friday afternoon in an effort to resolve this issue, but I haven't heard back from them yet. The only thing that concerns me is that I bought this Bonez system in 2014 and had it in storage until last week when I finally installed it. My backup plan might be to buy a RB down pipe and Bonez cat for an S5 NA, and just eliminate the pre-silencer completely. So, I guess we'll wait and see how this all plays out.
Seems as though one item is corrected and then another pops up.
Odd that the right side seems to be in place, but not the left. You'd think that if the left side is down, the right side would be up
One side was always slightly off (don't remember which side), but this is completely unacceptable. The y-pipe inlet and cat were misaligned by maybe a 1/4" due to the Bonez system not fitting properly. I had to force the pipes into alignment with a pry bar in order to bolt them together. This was difficult because these pipes are both very rigid. The whole exhaust system is screwed up due to improperly fitting Bonez system.
05-19-19, 06:12 PM
