ZoomHeart

This is my cherry post(be gentle).

Is my diagnosis wrong again? What are my options? What are my sources in replacing a propeller shaft?

History: My '83 stock GSL, 330+k, 20k engine, begins vibrating at about 30 mph. I checked for tire balance, inner belt separation, front wheel bearings and decided with my neighbor that my driver side rear wheel bearing was producing the noise which could sometimes be heard at about 5 mph with what I interpreted to be a high pitched metallic sound along with the vibration and low rumble. I interpreted the sound to be a thin metal tearing up. I didn't feel too much vibration in the steering wheel. Rather most of the vibration was felt in the seat. I concluded it was a rear wheel bearing going bad.

After reading through the archives I decided for a shop to do the work for me. Finding parts was a b itch but a local dealer sent to different locations for the collars, bearings and spacers and replaced both sides. After their test drive they reported a vibration to me that they believed was the u joint, drive shaft - propeller shaft or differential. Tomorrow they'll further diagnose.

I'm disappointed because I spent good $ on replacing something that may or may not have needed replacing. I shoulda had them diagnose first, not me. But maybe I had two things needing replacing the bearings and something else, too. They trusted my judgment and took my directions though. We both learned from that.

If it is a propeller shaft my decision right now is to choose between my options. As I understand it 83-85's don't have replaceable u joints on a drive shafts. Rather the whole propeller shaft has to be replaced. I may have an extra '85 propeller shaft but I think that I just have an 82 which I understand is configured differently and won't fit. I do have a perfectly good 85 GS 7 that I was going to use as a parts car but this propeller shaft would be the first thing scavenged off of it and would be disabling. So in a pinch I could start tearing that GS up. I understand that there may be a drive train shop here in Houston that could reconstruct the part using my original as a base for it for about maybe $250. Mazdatrix sells 'em for $400+ but converts to replaceable u joints.

Do you recommend that I go new with the Mazdatrix(I'm not rich and don't race)?

Or, do I rebuild if I can find a drive train shop?

Or, do I start cannibalizing a (potential)parts car that is perfectly good now?

Or, post a WTB?

Or, try to contact some members whose posts indicate that they may have my part and are relatively local?(In that this is my first post I can't PM as I need to post 3 times first.)

Or, as all the yards I've looked in have NO first gens, search wider in hopes of finding one?

Or, something else?

I FEEL like such a dumb a ss. Oh well, it's only money.

Help me smarten up.

trochoid

iTrader: (6)

Welcome to the forum. A good driveshaft shop can replace the non-replaceable u-joints, been done before. If that doesn't work for you, post a wtb in the 1st gen for sale section. You will need to know if you have the large or small flange as they changed mid year. If your's has bolts only, no nuts, it's the small one, with nuts, the large one.

In my sig line are links to the online FSMs, carb manual and other rotary related reading. Enjoy.
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ZoomHeart

You da man, trochoid. Thanx for your welcome and the succinct advise. I've enjoyed your posts while searching the archives and forum. I'm truly honored that my first reply was from you. You are definitely one who adds value. I'll post my results when I get some. I look forward to seeing images and linking once I get my first ten posts.

Kentetsu

Yep, chances are it's your U-Joints. A new drive shaft doesn't come cheap, so definitely look into having your "non-replaceable" joints replaced at a decent shop... (as T mentioned).

trochoid

iTrader: (6)

Sheesh, now I'm embarassed. I'm just here to humbly help out. But thanks for the ego boost anyway.

bliffle

Several guys have reported that the 'nonreplaceable' ujoints can actually be replaced. For as little as $25. One guy said that the inside circlips were simply staked and he nullified that with his dremel.

ZoomHeart

bliffle, once I get my 7 back I'll remove the propeller shaft and examine it. Your post gives me courage to apply some grinding touch to it and see if I can free up those circlips. Sounds very possible. I'll be observing and learning as I go. Thanks for the tip!

351W-Rx7

I'm new hear as well. If you apply heat to the yoke rings after you've ground the circlip the joint will come out easier. Personally I would just have replaceable joints installed by a shop. They'll have to weld in new yokes though. Good luck

mazdaverx713b

iTrader: (91)

i agree in having a shop replace the u=joints. remove the driveshaft and take it to the shop.

next, a perfectly good 85 shouldnt be used for parts. you can temporarily borrow the driveshaft from it, install it on the 83 and drive it if you need to. if not, then just do the easy thing and wait for the shop to replace the u-joints. what color is your 85?

1983GSP

for those interested the part number for the u-joint is 430-10a from rockford driveline. $21.12 apiece + $12.00 for shipping. the bearing cap diameter is .867in and the lockup is 1.515in. only the staked in u-joints use this. if you pull your drive shaft and there are no clips holding the u-joint, look at the outside of the cup on the inner diameter of the yoke or shaft. if you see little indentations all the way around the inner circumference, start cussing. hope this helps everybody.

ZoomHeart

Thanx Kentetsu, 351W-Rx7, and mazdaverx713b for your guidance.

mazdaverx713b I really appreciate your thinkin' on this. It makes total sense to me to swap out from my 'donor' car right now and give myself some time to find a shop and have the propeller shaft work done later and then reinstall the machined part back on the 'donor' car. The purpose of me having a donor car is to take the time or money pressure off of me to keep my daily driver on the road and give me time to make costsensical decisions by finding the right source or shop or product availability, etc.. Thanx for filling in just how that might work for me.

351W-Rx7, the parts guy at my dealer(used to be a speed shop, maz performance, now a conventional dealer but manned by the old speed crowd which is cool) did some searchin' for a shop to do his '91 2nd Gen propeller shaft and was quoted $140 by an outfit called Houston Drive Train. I'm goin' to check them out. It's maybe an hour away but he wanted quality at a low price so I'll rely on his research. I'm tempted to do the prep work you mentioned. 'cause I like the adventure and risk of trying something I've never done before, but this time I think that I'll abide by the axiom that the better part of valor is discretion.

mazdaverx713b, my '85 GS 'donor' car is V9 Toronado Silver with a black interior. I also have two other V9's another GSL and an SE. My '83 GSL is RH Sunrise Red. I have an
H1 Black '85 GSL, too. All of my other interiors are Burgundy.

ZoomHeart

Thanx for the info 1983GSP, I'll use it. I think that I'll gather all the parts but for now i'll plan on the shop doin' the finish work, especially if balancing is involved. But once I see everything laid out I may do some of the prep work. I don't know 'til I see it and a lot depends on how backed up I am on projects. I'm planning on taking pictures and post them for anyone who might follow me, but I'll have to learn how to do all that.

mazdaverx713b

iTrader: (91)

a black interior?? i've never a black interior on an 85. i've owned 21 first gen's and have only seen the black on an 81-83. this would be pretty neat to see. a small correction on the color name for V9. the color name is Custon Silver Metallic. Tornado Silver (K8) was produced from 81-84 and was dropped in 85 only to re-appear in 86. i thought the two colors were going to be pretty similar but they are in fact very different. i learned this two weeks ago when i picked up an 85 shell, color coded in V9 and stuck it next to my other shell, an 83, color coded K8. i have to say that i much prefer the Custom Silver over the Tornado silver. the H1, Sparkling Black Meatllic, is a very nice color. it was produced from 83-85 and you really don't see that color on many 7's. i don't mean to sound like a dick, i'm just making a small correction and don't mean to come off like an ***. i'mjust a color code guru and have been researching that crap for a couple of years now and i always want to share the info with others as i wish i had known the color code info years earlier.

ZoomHeart

mazdaverx713b , thanx for serving as a truth meter. [Personal Comment - Stand unapologetically in your truth.] :-) I appreciate your candor and am inspired to go read every color code and vin number from the fire walls to verify exactly what variety my 1st Gens are. I've owned 7 which is one third of your 21. By that ratio I imagine that you are at least twice as accurate in your understanding as I am. I appreciate your color code guruness and will report back by PM one of two things 1) some misunderstanding/inaccuracy on my part that I'll correct or 2) the rare variety in my possession. I'm curious now so I hope to check 'em out tomorrow.

For others, I did find two detailed 2nd Gen threads that have pics and further explanation of 'how to' and some tips on the non-replaceable replaceable u joints propeller shaft issue.

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/replacing-non-replaceable-u-joints-517657/

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/method-safe-removing-driveshaft-bolts-723002/

mazdaverx713b

iTrader: (91)

this is a helpful site for color codes: http://www.rotorhead.ca/topic.php?fldr=tech&cntnt=paint
i do notice that there are a few color names that do not match up with the U.S. spec catalogues and i would guess the reason that is would be that in some instances, perhaps Canadian color names may have been different than U.S. color names. one example is color code L6. in the U.S. that color is called ocean blue metallic. the site has it listed as royal blue. another example is the T9, which is listed as new trad.... here in the states, thats desert brown metallic. most of the others are pretty spot on. i do use that site for reference though.
being the owner of 24 RX-7's over the years (currently 6 whole and running and two shells) doesnt make me any more knowledgeable than the next guy though. i guess it just meant that over the years i've come across some good deals! in all fairness, i do know quite a bit about cars and my knowledge is mostly about 7's. they are my passion. i feel like i could take one apart and put it back together in my sleep, lol.

ZoomHeart

mazdaverx713b, I'm thinkin' this color code theme should be a new thread, but being a newbie I don't know how to do that, maybe you can do that and keep the original thread limited to the mechanical topic. However, I'll reply to your color code topic now and do it here rather than PM 'cause I think there's value for members interested in a search on the color code topic and I want to move ahead without waiting for the creation of a new thread from this old one, one in which the first content on color is preserved.

Anyway...

I double checked my vins and color codes and the site you listed. Several interesting questions have now arisen.

First, JM1FB3313F0879450 appears to be produced in December of 1984 but I believe that is considered as a 1985 model and has been registered as such in California. It is color coded V9 and has a black interior. So I have an outstanding question about its "year" 'cause I imagine that the December produced car didn't get imported until 1985.

Second, I discovered that my "Sunrise Red" '83 GSL is really an R3 which is "Renaissance". I had remembered my color code as RH but I was mistaken. However from your color chart(on my computer screen) the actual paint on the car looks like it matches Sunrise not Renaissance. So, I have a question about that. Looks like my '83, JM1FB331XD0731003, woulda been manufactured in Feb or Mar '83 but I can't tell from the chart below.

Third, as I remember, I think my '85 SE(blown modified REPU side 6? ported aspirated 13B with mikuni carb) still in California, not with me here now in Texas) is a K8. What reminded me of that was your mention of K8 Tornado. However, to my naked eye my SE matched closely my V9's when they were parked close but not next to one another. But it also seems to my memory that the SE might have been only slightly lighter than my GSL's. Yet, another complicating factor in my foggy mind is that I cannibalized my first 7, an 82 GSL that was light silver in color and maybe that's where I got the K8 in my head. So, that means maybe my SE is a V9 after all. but from your chart I think the V9 SE was only produced in 1984. But, my SE, JM1FB3324F0879336, looks like it is a December month-mate 1984 to the black interior GSL in question above. Once again, would a 1984 manufactured SE make it to the states in 1985 and be registered as an '85?

The code for the 7's in question shows an "F" in the year location in the vin which makes both the GSL with black interior and my SE 1985 models. The chart below seems to print out the layout maybe a little different than it was intended. To make sense of them, I had to interpret some of the charts which seemed to not line up properly. I haven't done due diligence and looked in some of my sources sitting on my shelf, but I will later on.

You commentary has opened up a very interesting line of investigation for me. Do you have any comments on what I wrote above? Does anything not pass your smell test?


From two79rx7's post:

https://www.rx7club.com/1st-generation-specific-1979-1985-18/whats-different-between-sa-fb-124806/

Vin Info:

Model Year VIN Ser Numbers
1979 SA22C - 500001 +
1980 SA22C - 600001 +
1981 FB33 - 500001 + (USA)
1982 FB33 - 600001 +
1983 FB33 - 700001 +
1984 FB33 - 800001 +
1985 FB33 - 856209 +

How to interpret the VIN (Chassis No.)

Vehicle Identification System for Mazda RX-7 series (1981 - )

Vehicle Identification Number (VIN) for RX-7 (1981 and later year models)
consists of World Manufacturer Identifier, Vehicle Description Section (VDS),
Check Digit, Model Year Code and Production Serial Number which is
sequentially
numbered within each VDS.

Shown below as an example is the VIN for a Mazda RX-7 (1981 model).

____ VDS (Vehicle Description Section)
|
____V____
J M 1 F B 3 3 1 4 B O 5 1 2 3 4 5
----- --- --- - - - - -----------
^ ^ ^ ^ ^ ^ ^ Production Serial Number
| | | | | | |
| | | | | | |__ Assembly Plant Code (O = Hiroshima)
| | | | | |
| | | | | |__ Model Year Code (B= 1981, C = 1982, D = 1983...)
| | | | |
| | | | |__ Check Digit *
| | | |
| | | |__ Miscellaneous Identification Code **
| | |
| | |__ Body Style Code
| |
| |__ Car Line Code (FB = RX-7 Series)
|
|__ World Manufacturer Identifier (All Mazda Passenger Cars are
identified by JM1.)

* Check Digit is included as a VIN security feature to permit law enforcement
verification of the authenticity of a suspected illegal VIN plate. This
single digit number is determined, based upon a complex mathematical
formula which is applied to each vehicle's VIN number.

** Miscellaneous Identification Code identifies major components such as
engine, brake system, cab type, etc. However, if all models of the same
car line use the same such components, this code is indicated as a numeric
character "1" only.

List of Monthly starting VIN (Chassis No.):

1983 1984 1985
JAN 815218 881177
FEB 819695 885029
MAR 824687 889474
APR 829422 893766
MAY 834333 899625
JUNE 839137/850001 905108
JULY 850015 909988
AUG 856209 912608
SEPT 800001 861829
OCT 800882 866965
NOV 806531 871511
DEC 811185 876904

elwood

iTrader: (1)

I have a TII tranny in my FB, and I have a custom made driveshaft, which was never perfectly balanced, like my original one was. I even had it re-balanced, which improved the condition, but didn't make it as good as OEM.

1. Have others experienced this problem? What did you do?

2. Is there an OEM driveshaft that might work? Mazdatrix' driveshaft for TII tranny with NA third member? Is the length the same / is the rear flange the same as a GSL-SE flange?

Kentetsu

Elwood; I don't have any information for you on your topic. But I was wondering, why can't they balance the driveshaft? Seems like they should be able to. Are you positive that an unbalanced shaft is what's causing your vibration?

elwood

iTrader: (1)

I'm not 100% sure that driveshaft balance is the issue, but it ran smoothly before I swapped trannys, and it didn't afterward. I understand that FBs are very sensitive to driveshaft balance, and I suspect that the OEM shafts are balanced to much higher precision than the average aftermarket shop can match.