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Index > Engine/Drivetrain > Thread: 78 rx-4 clutch doesnt work, what does?
Thread: 78 rx-4 clutch doesnt work, what does?
rdahm


1st Gear
www.TurboRX7.com
Posts: 26
posted January 27, 2004 03:16 PM

78 rx-4 clutch doesnt work, what does?

I had been told by many people that the RX-4s clutch was the same parts. It is not. Does anyone have a used clutch or know where to get a decently priced clutch? I just need to get the thing running. I can tear it apart later to replace the clutch etc.

Please help. If i dont finda clutch the REPU has to goto the junkyard. I want to restore it. :-(

Rob
____________
'93 Touring RX-7
'88 GXL RX-7
'74 REPU

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straightrepu


Redlining
Posts: 232
posted January 27, 2004 03:52 PM

flywheel

I`ve heard that you need to replace the flywheel with one from an RX4 to make it work.
____________
74 restorepu

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nwaco


Redlining
Posts: 407
posted January 27, 2004 03:58 PM

For the record.....

the clutch, pressure plate, and flywheel (as well as the release bearings, etc.) between an RX-4 and a REPU are all different. Craig is correct, you must change all three to use the components of one on the other.

Both setups will bolt up and fit the splines, so to use RX-4 parts, you must change the whole setup.

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repumax


Redlining
Posts: 427
posted January 27, 2004 07:10 PM

I think I can help.....

......I have a flwheel,clutch,and pressure plate from an 85 6 port.Its all used but was working perfect when I took it all out.If you are interested I'll let it go for cheap.
____________
1974 Mazda Repu
1986 Yamaha RZ 500
1988 Yamaha YSR 50
1991 Suzuki RGV 250
1992 Yamaha TZR 250 SP
1996 Aprilia RS 250
2003 Ford F-450 6.0 Diesel
2004 Mazda RX8
2006 Yamaha Banshee
2014 18' Eclipse Toy Hauler

       
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Klaus43


Rotorhead
Posts: 1259
posted January 28, 2004 12:49 PM
Edited By: klaus42 on 28 Jan 2004 12:53

So, I must have had some different parts in there...

I was under the impression that the only difference between rx-4/cosmo and REPU clutches was the 9-bolt clutch cover on the REPU, as opposed to the 6-bolt on the other models.
Now you guys have me wondering just what I was/am dealing with in what I have... and who put what together, and was how 'out to lunch' in what they told me...

For the record, what IS the difference between REPU and rx-4/cosmo flywheels, besides about 3 lbs. of weight, and three additional bolt holes?

And the clutch disk... what precisely are the differences? I still don't think there are any... except, perhaps, for part numbers...

...which brings us back to the clutch cover: what precisely are the differences there? (Except for 6 vs. 9 bolt...)

I could swear I've seen throwout bearings that list both rx-4 and REPU applications for the same part...

Also, what year(s) might/do indeed cross over, vs. when any actual changes took place?

Robert, are you 100% certain what you had in there was indeed all original REPU clutch parts to begin with? It pains me greatly that, apparently, I passed on bad advice... Whatever you do, DO NOT junkyard your REPU just 'cause you have a grenaded clutch!
There are too many better alternatives, of which restoration is but one...

Let me join you in a great big "Aaargh!"

       
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brad


Rotorhead
Posts: 1672
posted January 28, 2004 02:21 PM

Clutches are out there Rob, as are flywheels!

If you even want to go hi performance, racingbeat.com can sell you a light steel or very light aluminum flywheel and clutch that will work with REPU.

I bet the auto parts store has clutches for stock REPU flywheel. Even if not so, I bet racingbeat.com can help.
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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Klaus43


Rotorhead
Posts: 1259
posted January 29, 2004 04:04 PM

OK, Rob...

Could you be more specific about what differences you've encountered, and why what won't work?
Ken and Craig: You guys got the lowdown, 'for the record', piece-by-piece specifics?
What are the odds, say, for example, a '74 rx-4 disc is identical, while a '78 is not...?
I could swear I knew what was what... now you guys have me questioning my sanity--and I'd at least like to be able to go out and definitively ID what's on some of my core collection, just so I'll know for sure... nevermind if I can make it up to you, Rob, by finding you a needed part...
Aaargh!!!

       
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rdahm


1st Gear
www.TurboRX7.com
Posts: 26
posted January 29, 2004 08:47 PM

The two differences were: 1. RX-4 Clutch was smaller diameter. 2. The disc was shaped as the spline gear would hit the engine before the pad would touch the flywheel.

I got mine resurfaced. I called around frantically for a replacement and I called Rhino Pac parent company. I found a local guy that does R&R (resurfacing and reattaching ?) he completely replaced my disc.

I got the truck moving! It is so awesome. I have saved one. It shifts through the gears nice and fine. There was some squealing until the pad wore in. I am so excited. Ken I will be contacting you shortly about those lights.

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Klaus43


Rotorhead
Posts: 1259
posted January 30, 2004 01:34 AM

I must be some kind of stupid.

I'm glad you got her moving, Rob--and I'd like nothing better than to post some pics here of the different clutch assemblies, so as to finish the lesson for me, as well as for anyone else that ever needs to ID what they've got...
But, as I have yet to figure out just how to get that to work, as well... I should probabaly retire my sorry ass from this forum now.
My humble apologies; I'must've been misled...

       
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Jeff20B


Moderator
Posts: 661
posted January 30, 2004 01:57 PM

Whew! I'm glad you got it togther. It would have been stupid to let a clutch problem sentence a truck to the scrap heap.

Klaus, again, you're starting to get it. Basically, the differences are great. The REPU disk is 225mm, but is inset(offset) deeper into the flywheel; presumably to make room for a thicker perssure plate. Also, any '71-'78 throw-out bearing will work. We once tried a '71 -'82 215mm disk that ended up dying when the lining grenaded from the marcels (is that what they're called?). I have a picture of some of the pieces here. (click it and drag and drop the e or simply copy and paste this URL) http://www.geocities.com/cd23c01/clutch01.jpg

By the way, that 215mm disk damaged the edge of the eccentric shaft. Reason why is because it did not have the offset. Luckily a 1/2" air wrench with a 2 1/8" socket on it was enough to spin off the 54mm nut past the slightly damaged threads. It went back on just fine.

In short, REPU flywheels, clutch disks, and pressure plates are unique. However, you can swap it all over to GSL-SE parts if you wanted to because the counterweight offset in the SE flywheel matches the rotors and front counterweight of a stock REPU rotating assembly. Another good thing about this swap is the 225mm disk. It'll have the same surface area as the original disk, but with easily replaceable parts. Aftermarket parts should be strong enough for the use and abuse they'll get in a REPU. :) I guess the inertia will be lower, but with a '74 diff geared at 460 or some-such, that's totally not a problem. I'd suspect even the '77 390 would be just fine.

Note: the "Rotoscoot" '77 REPU further down my cars webpage had a GSL-SE flywheel and then got a light steel flywheel and still does well enough. The 7" SC probably helps a little too. http://www.geocities.com/cd23c/cars.html#rotoscoot

       
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rotarydave


Hauling
Posts: 108
posted January 31, 2004 10:01 AM

Are you sure that the counterweight matches on the GSL-SE motors i don't think it does..... i don't want to cause a major issue here, i understand what you are saying. You can change flywheels but please make sure that the counterweight front and rotors and flywheel are all a matched set or you could be asking for bearing issues, everything said about the clutches is accurate in addition the clutches and pressure plate (repu) is built to withstand more abuse because of the GVW rating of 3/4 ton. I do not reccommend most of the aftermarket REPU clutches as they are not up to the quality of the OEM parts if I have to do it now i will go with a RB part if it is available or switch to a RX-4 flywheel and use the Street and strip plate and disk.

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Jeff20B


Moderator
Posts: 661
posted January 31, 2004 02:19 PM

Well, I can tell you this much; the front counterweights of both engines have 1757 or 1575 stamped on them (either way, they're both the same). Just ask j9fd3s for more info.

Dave Atkins has said the '74-'85 rotors are all the same compression. I thought the '74-'78 were 9.2:1 and the GSL-SE were 9.4:1. He said they're all the same. I was like "uh, ok". Check out this Mazdatrix link for rotor weights to see why I was a little confused. http://www.mazdatrix.com/faq/rotorwgt.htm I'm not sure who is correct at this point.

Then check out this link to see that the front counterweight is appearantly the same for '74-'85. http://www.mazdatrix.com/getprice.asp?partnum=11-5110-N304

Also see this link showing the rear counterweight is also the same for '76 to '85 rotors. Why it does not say '74 is beyond me. http://www.mazdatrix.com/getprice.asp?partnum=11-751A-1029

There is enough evidence here to suggest that it's fine to use a GSL-SE flywheel on a '74 rotating assembly. However, I'd still call up Mazdatrix and ask. Hopefully I'd get someone on the phone who's actually done such a swap before.
____________
'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7

       
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brad


Rotorhead
Posts: 1672
posted February 04, 2004 03:30 PM

quote:
Are you sure that the counterweight matches on the GSL-SE motors i don't think it does..... i don't want to cause a major issue here, i understand what you are saying. You can change flywheels but please make sure that the counterweight front and rotors and flywheel are all a matched set or you could be asking for bearing issues, everything said about the clutches is accurate in addition the clutches and pressure plate (repu) is built to withstand more abuse because of the GVW rating of 3/4 ton. I do not reccommend most of the aftermarket REPU clutches as they are not up to the quality of the OEM parts if I have to do it now i will go with a RB part if it is available or switch to a RX-4 flywheel and use the Street and strip plate and disk.


yes the gsl-se flywheel and counterweights are a perfect match for REPU and Rx-4 13b 4-ports.

They all use the same heavy rotors.
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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