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tincup

Rebuilt a "wide ratio" tranny using 5th gear from a "close ratio"

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tincup    10

I had my transmission rebuilt this past week by a local mechanic and he was able to use the 5th gear from an '81-'83 close ratio 5-speed in the '77-'80 wide ratio 5-speed he rebuilt.

 

This keeps the best of both transmissions. The superior acceleration from the early one and the taller cruise gear from the latter.

 

My mechanic was resistant to write up how he did this and I'm no mechanic, but he did say he assembled and lined up everything as if the tranny was in neutral and then had to drill holes in a difference place in order to make it work. I apologize for not being more helpful, but I can say this is possible because I've driven the finished product.

 

When I asked him to try this, he warned me their would be a large difference between 4th and 5th gear but I had driven both transmission and wasn't worried about it. After assembly, he said their was much less of a difference than he expected. I'm very happy with the setup since I get the acceleration back and I keep the lower rpm's at cruise.

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johnc    724

This isn't any kind of big secret. SCCA EP racers have been building low buck close ratio transmissions for years using the late ZX NA 5 speed and a truck .86 5th gear. Its been posted here on HybridZ and other other sites for at least 5 years.

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Maybe not...

 

But it might be a new idea to the people that don't know the unabridged history of Datsun, aren't mechanics, or haven't been into Z cars / lived on the Z forums for 5 years. I certainly haven't seen a sticky talking about it at all, so I think bringing something like this back up is a fine idea until there is a sticky or reference mentioning such a thing. How would a new person know about this otherwise... certainly not by searching... if they didn't know it existed to search for to begin with. :wink:

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Six_Shooter    13
Maybe not...

 

But it might be a new idea to the people that don't know the unabridged history of Datsun, aren't mechanics, or haven't been into Z cars / lived on the Z forums for 5 years. I certainly haven't seen a sticky talking about it at all, so I think bringing something like this back up is a fine idea until there is a sticky or reference mentioning such a thing. How would a new person know about this otherwise... certainly not by searching... if they didn't know it existed to search for to begin with. :wink:

 

QFT!

 

This brings new (to me) idea, that I might have to explore, once I get my car converted to manual. It would work well with my (according to at least one site) lower final drive ratio than a factory manual equipped car, great accel with nice cruising RPM. :D

 

Thanks for bringing this to the newer members attention. :)

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JMortensen    235
parade+rain= this post ^^ lol

I am not saying this to make the original poster feel bad about their purchase, but I've got a different opinion about what would be the best way to do this. The perceived advantage of the lower gearset is more than overwhelmed by the huge gap between 2 and 3 in that transmission in my experience. The more peaky the engine is the worse the effect of the gap. The better setup would be the ZX transmission with its closer ratios with the truck 5th gear and then to get the acceleration use a lower rear end gear. Of course that's not the end of "better thans". Better than that would be one of the old option 2 comp boxes. Better than that would be Coffey's old transmission. I'm sure it goes on from there but I am not aware of anyone who has gone farther than that.

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240swapped    10

is the slag between 2nd and 3rd a Nissan trademark or something? it was terrible in my KA 5spd in my s13, and when i did the rb20 swap i expected better....nope. still falls on it's face when driving normally. had a 5spd in the 76, same thing. lost 1st and 2nd in it and therefore put the 4spd in, same friggen problem. in a bulk buy i got some really cool stuff (an old autocrosser seller) including unopened, brand new in box e31 and p90, a couple race motors (1 l24 and 1l28). the mystery item is a 5spd tranny that i have sitting in my storage unit. not getting my hopes up, but i watched the video with keichi tsuchiya driving the spirit garage z and i noticed that 1st is in the down position. this tranny has a shift knob on it with 1st in the down position. tomorrow i'm riding to smyrna, TN to buy an '02 GS300 for a daily so that i can get back to tooling around on the z's and the s13. i'm sure i'll have to install and drive the new tranny to get any answers unless you guys have some. as this is off topic, feel free to just pm me the answer, or if the moderators don't mind and it's a quickie answer, i'd appreciate that as well. please and thanks for any help!

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johnc    724

My comment was related to your mechanic's resistance to letting people know how to do this gear swap.

 

My mechanic was resistant to write up how he did this and I'm no mechanic

 

Since you didn't bring any tech to this post, I thought I would remind people with my post that swapping out 5th gear on these Nissan trannies is a common thing and they can find the informaiton in many other places. I'll even copy one of my posts from a long time ago that actually gives part numbers and gear ratios:

 

Poor Man's EP Close Ratio 5 Speed

 

Later 5 speed (81 through 83) from the NA 280ZX with a Nissan .86 overdrive 5th gear set part number: 32310-58S54. That will give you:

 

1st 3.062

2nd 1.858

3rd 1.308

4th 1.000

5th .864

 

You're still stuck with the brass synchros but the trans can be built for under $900 and should last half-a-season. Removing 1st also gives a the weight break for a 4 speed box. Eddie Raddatz is the one to call at (deleted) for the details.

 

 

A "Thank You" would be nice, but I doubt I'll get it... :-(

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That's definitely some "Thank You" worthy material there... so indeed, thanks!

That part # will be useful.

 

After re-reading your post I see what you mean though. At first glance it looked like a "this thread is worthless" post, not a "check out the .86 truck 5th gear" post. I get your meaning now :mrgreen:

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gereed75    0
Posted (edited)

OK,  I know this is an ancient thread and I know that everyone is supposed to know how to make the overdrive swap to a .864 in a 79-83 NA 280zx trans,....  but that was then this is now.  Can't find any of these old threads where this was done routinely by every EP SCCA racer ever..

 

So sorry, but how is this done>>  I have the tranny and I have the  32310-58S54 gearset. What is required to make it happen?? Is it just a matter of pulling the .7xx gearset and installing the .864?? How much dissassembly has to happen???

 

Thanks 

Edited by gereed75

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NewZed    56

make the overdrive swap to a .864 in a 79-83 NA 280zx trans

 

 Is it just a matter of pulling the .7xx gearset and installing the .864?? 

 

Looks like you have to disassemble the transmission to get the O.D. gear off the shaft.  1982 MT chapter..

 

And it's 80 - 83, not 79 - 83.  79 for sure and maybe early 80 are the "wide" ratio transmissions.

post-8864-0-55522100-1501033755_thumb.png

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