r180 AT diff into MT

[mlc240z]

was wondering if it was worth swapping r180 at diff(3.54) into my 71Z with stock mt diff(3.36)? i know the way everybody goes is with the better ratio (3.90 and 4.11) R200's, but i might be able to get one cheap. i'm guessing it would be a no modification direct bolt-on since they're both r180's.

i assume it would be a small improvement off the line, but if anyone here has experience or thoughts, i'd appreciate the input.

if it's a tiny improvement, it wouldn't be worth the trouble unless my original dies.

thanks guys.

[240ZX]

It's definitely a direct swap and bolt in deal. By changing from a 3.36 ratio to a 3.54 ratio you will have a 5% lower gear ratio, improving accelloration for sure! Of course you will want to change out the speedo gear in the tranny to one matched for a 3.54 diff, so your speed reads correctly. Also, when your in top gear cruising the down the highway, you will be revving the engine a little more for the same given speed as before (approx. 500 rpm more). You will definitely feel the difference!

[beandip]

was wondering if it was worth swapping r180 at diff(3.54) into my 71Z with stock mt diff(3.36)? i know the way everybody goes is with the better ratio (3.90 and 4.11) R200's, but i might be able to get one cheap. i'm guessing it would be a no modification direct bolt-on since they're both r180's.

i assume it would be a small improvement off the line, but if anyone here has experience or thoughts, i'd appreciate the input.

if it's a tiny improvement, it wouldn't be worth the trouble unless my original dies.

thanks guys.

I wouldent go through the trouble for such a little difference. Personally for me as a daily driver I wouldent go with a 411 , 390s maybe , If you do much hiway or freeway driving look for a 370 diff. I think you would like them with the L-24 . The 390 is great off the line but you will be spinning some Rs at freeway speeds and that will get old. These Zs have the different ratioes '81-83 have 3.90 in the N A cars and '79-'80 ZXs 3.70 go to this web site geocities.com/zgarage2001/ tons of great info there on this . click on performance tips and scroll down to the diff section. Gary

[mlc240z]

not using as a daily driver, just for occasional fun.

already had that site in my lllonnggg list of bookmarks, great info.

with the 4spd, kind of figured the higher buzz at highway speeds, 5spd swap is one of my dreams. here in the northeast, Z anything in the junkyards is hard to find (rust). so i figured if i could get a 3.54 reasonably priced, and i was pulling everything down to replace bushings and mounts anyway..................

i like the idea of the 3.70, seems like a good 'compromise' but from my research, the 3.70 was an r200 and that involves the half shaft/mustache/possible flange swap. i don't think i have access to all the parts and i don't think i'm brave enough to tackle that yet.

[zguitar71]

I ran a 3:5454 in my 71 with a 4 speed for a long time and loved the ratio around town but on the highway it was a little high revved. The 3:5454 with the 4 speed is a 12.76 overall ratio, nearly equil to the 12.57 overall ratio of the 81-83 5 speed with a 4:11. If your not driving the free ways all the time it is a great ratio to have.

[beandip]

I just pulled my 180 and installed a R-200 used the same half shafts I had and changed the M Bar that is all. Not a big deal . the bolts for the M bar to the gear housing are larger for the R- 200 so you will need them. If your half shefts have 4 bolts on the end at the gear housing they will work.

[zguitar71]

If you do change to an R200 you might need to find the curved aft suspension cross member that the lower suspension arms bolt to. The production date of your Z falls right around the time they changed to that type of cross member in order to shift the diff back for better geometry. I had to do this on my car (1-`71). I believe it was part of the difference between the series II and III 240's. The z barn sells a kit to change over to an R-200 for zcars produced before and after the the change.

I really liked the setup you are looking into but nothings better than a 5 speed. If your gonna change all the bushings and stuff you have done 1/2 the work towards changing over. Changing to an R-200 is not hard, the 5 speed swap is the time consumer (especially if you have a series I or II).

The only reason I changed to an R200 was for the lower cost of the LSD units. I rather use an R 180 from a 4x4 truck (4:38 gearing, the same I have now in the R200). The 240 is not set up for the wider body of the R200. Read this article http://www.betamotorsports.com/benchracing/index.html, it explaines what I am talking about very well. If you never race your car then the R200 is just fine though. Hope I didn't give you too much to think about.

[Curtis240Z]

Since you are changing bushings it would be a convenient swap and when you get the 5-spd you will have better matched ratios.

______________________

5/71 240Z, L28, triple Mikuni 44s, 5-spd, R200, Crane HI-6, blah blah blah.....

[beandip]

Just a thought , if you want a 3.70 diff in a 180 unit , look for a maxama with a manual trans . They have the 180 and in a 3.70 ratio. Gary :rambo:

[mlc240z]

oww, my head now officially hurts......

zguitar, i appreciate the first hand info on the 3.54, that's what i'm looking for if i can swing a deal on a 3.54.

curtis, unfortunately money is the main reason i have to postpone the 5spd swap. just got my baby and i'm trying to take care of all the 'little' (read expensive) things before i move on to the big modifications.

gary, what year if you know? even though a stick maxima might be harder to find here than a Z, it's an enticing option.

just want to know why my dream of unlimited funds, a warehouse of new parts and a built-in lift in my garage can't come true.

many thanks for all the input. this is what i needed to help make the call on a swap.