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Index > Engine/Drivetrain > Thread: SA 5spd Swap/Speedo Question
Thread: SA 5spd Swap/Speedo Question
kansei


Redlining
Wankelized
Posts: 423
posted April 28, 2008 01:31 PM

SA 5spd Swap/Speedo Question

I seem to remember this being touched on in the past, so my apologies for not recalling it exactly and what the answer may have been.

Like alot of us, I have an SA five speed trans in my truck. I know the speedo is off, but have no idea if it is a linear or progressive error, and want to know if anyone has done the research to determine if there is a way to get the speedo to read an accurate speed. For instance, using the speedo drive gear from a 1980 B2000 automatic (just made that up as an example)? I know I'll probably get a bunch of replies saying it isn't that big a deal, but to me it is. Any ideas or anyone know somewhere I can call that may be able to help?

Thanks,
Neal.

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jfaplanet


Redlining
Posts: 356
posted April 28, 2008 02:20 PM

Speedo

Neal, Put a 4.11 chunk out of a courier in there and it will be close. Since the SA/FB tranny was in front of a 3.90 rearend, and you'll get better gas milage and still have good power. Thats what the Red truck has. Or you can go to the trouble of finding a gear reduction unit to put on the cable and change the gearing so that the speedo will read right. The gear from the truck 4 speed could also be used but it has to be used as a set. Meaning both the one on the output shaft and the one on the end of the speedo cable must be used. Its not just as simple as moving one gear to the tranny like on a chevrolet. Good luck and if you want to talk about it more. U know my number.
____________
74 REPU "Red"
74 REPU "Jethro" "TII"
74 RE-Courier vert
79 SA-SE(aka deathtrap)
79 SA-SE-FC (project
turbo)
http://home.bellsouth.net
/p/PWP-crgj
TN Forum:
http://tnrotary.10.forume
r.com/

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MAZDAMARK


Hauling
Posts: 139
posted April 28, 2008 02:31 PM

Never did the research, but the below is from solomiata:

SPEEDOMETER GEARS:

The speedometer gears and gear housings between all the late model(1984+) 'M' transmissions interchange. If you have installed different rear ratio gears or different diameter tires then you will need to change the speedometer gears in the transmission to keep the speedometer accurate. The speedometer gear housing bolts to the transmission and is easily removed since it is external to the tranmission

Mazda makes speedometer gears for the late model 'M' tranmission with 17-23 teeth. The steeper the rear ratio gears or the shorter the tire diameter the more number of teeth is needed to compensate. The 90-91 Miata comes from the factory with a 20 tooth speedometer gear (which makes the 4.30:1 gear about 5mph fast). The pitch of all the speedometer gears is the same and only the diameter of the gear is different (1978-mid83, with the exception of the 626, use a coarse drive gear and are not interchangable). The different gears housings are offset to account for the diameter change (see picture)

Speedo gear chart
Car tooth count gear color notes
84-85 12A RX-7 17 green '79-83 coarse gears
84+ B2000/2200 truck,
84-85 13B GSL-SE RX-7
18 purple
86-91 RX-7 convt 19 red (small diameter)
90-91 Miata, 86-91 RX-7 20 black
1989-90 RX-7 GTUS 21 white 4.30:1 rear ratio
1979-82 RWD 626 22 Red
92+ Miata 23 Red


____________
94 RX7
89 RX7 GTUs
85 GSLSE
88 323 GTX
1975 REPU

       
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kansei


Redlining
Wankelized
Posts: 423
posted April 28, 2008 02:45 PM
Edited By: kansei on 28 Apr 2008 14:46

Thanks...

Charles- thanks for the input. I put a post wanting an original 4 speed trans to swap the speedo gears out.

Mark- thanks for the info, that helps, but their info is a bit vague. For 1984/5 RX-7s, there were two rear end ratios, but they both used the same speedo gears? I guess they could have, given they had different wheel/tire sizes... Likewise for 1986+ RX-7s. I guess that doesn't really matter since I am using 1974 and 1980 pieces.

We'll see what comes of this once I can track down a stock '74 4 speed trans. Anyone got one for sale?

Neal.

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mwpayne


Hauling
Posts: 195
posted April 29, 2008 01:49 PM
Edited By: mwpayne on 29 Apr 2008 13:50

I've got a 4 speed out of a 74 you can have for shipping if it's usable to you. The 1st, 2nd, and 3rd gears are whiny, sychros are fine. I was going to just give it to a neighbor who gets a few bucks for junk hauling otherwise.

       
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jfaplanet


Redlining
Posts: 356
posted April 29, 2008 01:55 PM

Mike

I'll see about getting it shipped to me. Got some friends that go to UT up that way. Then I can get the parts out that neal needs and ship to him. Unless he wants to ship the whole thing to him. His call!

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mwpayne


Hauling
Posts: 195
posted April 29, 2008 01:58 PM

Cool, I can meet someone with it, glad to help. If I need to meet you at say, Cookeville, glad to, no problem.
We'll get Neal a tranny!

       
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kansei


Redlining
Wankelized
Posts: 423
posted April 29, 2008 02:01 PM

Mike,

That's excellent news!! I'll take it! Thanks!! Any parts I may have here that you need? Send me an email and I will respond with my address so we can figure what shipping will be (kanseirotary -4t- charter.net). I have to get a bed shipped from Klaus' place, so hopefully I will have the cash to do them both so no one has to wait on me.

Charles- I appreciate the offer, but I'd prefer to take the whole trans right now so I have a true '74 box to return my truck to absolute stock one day if I decide to actually pull the overdrive trans. I actually have a rebuild kit (new synchros and some bearings, anyways) for the 4 speed unit, so I could actually freshen Mike's trans up down the road.

I can't believe someone actually had one laying around still.... and it almost got scrapped??? I'll pretend you didn't actually say that, Mike. Bad Mike, Bad.


Neal.

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mwpayne


Hauling
Posts: 195
posted April 29, 2008 04:01 PM

OOooo..I haven't had a good spankin' in days..

Well, I just didn't think anyone would want an old wore-out 4 speed..everyone (like me) wants a good 5 speed, or so I thought. Goes to show what the hell I know..:)
Now, the hard part...how do you ship it? I don't have a pallet, do you handle it from your end?
I'll email you my phone number, we'll get it all worked out.

       
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