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Differential ratio


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My car is a 79 280 ZX (GL version which I think has the 3.54 R180 diff) with a currently completely stock 1989 350 V8 and 700 R4 trans from a Firebird Trans-Am GTA (240 hp when new and I think about the same amount of torque-I don't have the numbers in front of me). Someday I will probably up the power of the engine but I'd rather work on effectively getting the power to the ground first. I've got urethane bushings everywhere and have rebuilt the stock brakes and added stainless lines.

 

I'm probably going to buy a Quaife Limited Slip R200 differential through Paul Stod of Performance Racing Products in Rochester, New York. He has gotten good references from some people on the IZCC listserv. He was trying to put together a deal to get a much cheaper price on an R200 LSD but not enough people were interested. Since that has fallen through, he is offering an R200 Quaife for about $1100. I've asked for his thoughts on my questions but would like your opinions as well.

 

The 700 R4 has the following gear ratios: 1st--3.06

2nd--1.62

3rd--1.00

4th--0.70

 

My intent with the car is to perhaps (I haven't done either yet) do some auto

crossing and some 1/4 mile drag racing at the strip. I'm not interested in high

speed track events but I am interested in a "reasonable" ratio for the highway. If I had to choose auto crossing versus drag racing, I'd lean toward drag racing. So far, I've driven the car about 1,000 miles per year (over a six year period) although I'd like to do a little more highway sightseeing/touring. I don't use the car to drive to and from my job. I don't have the numbers in front of me, but the engine is known for its low end torque--I'm guessing the torque peak is reached by 4,000 rpm. I haven't chosen wheels and tires (I currently have the 14" stock rims) yet, due mostly to my uncertainty of how the tire height, trans ratios, diff ratios, torque peak, etc play together. I don't yet understand the effect 14" rims

versus 15" rims versus 16" rims would have on the overall ratio. I'm in love

with the look of Panasports and they are available in all three sizes although

I'm sure the selection of 16" sizes are more limited than the 14" or 15" sizes. I'm unclear how going to larger wheels will affect drag racing versus auto crossing. I'm slowly understanding this stuff but there are a lot of gaps in my understanding of how all of this plays together.

 

I'm guessing that a 3.54 ratio with 12 mm ring gear bolts might fit the bill best

but I'd like your thoughts. I'm told that there is more availability of ring gears with 10mm bolts. My notes show that the 81-83 cars w/ turbos with either manual or automatic trans had the 3.54 ratio as well as having 12 mm bolts. Are my notes accurate? I've saved a lot of notes from the IZCC listserv (thanks in particular to Ross Corrigan) but oftentimes I still get lost.

 

I'm going to look at a spreadsheet someone has posted

(http://www.geocities.com/dave240z)

that apparently allows one to play with the variables of ratios, tire sizes,

etc. I'm not sure how good it is.

 

Any ideas from the group would be much appreciated. John Haag

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Hi John,

 

I understand that a company (can't remember the name) still makes a "brute Force" clutch posi unit to fit the R200. Michael (HP Tech) is doing one of those - I think a new posi unit from them is less than $400. The Quaiffe is a great unit, but $1100 is steep, and it would warrant new ring and pinion, in my opinion, which is about $400 or more from Nissan. I'm not sure what size bolts the "Brute Force"? unit takes. Search on HP Tech here and find Michaels phone number if you're interested.

 

Wheel diameter won't affect tire diameter if you go to the correct "series" of tire. There are a bunch of tools on the net for figuring this, but the equation to figure it is simple:

 

Tire Dia. = 2*(section width (mm)*(series/100)/25.4) + wheel diameter.

 

So a 225/60-14 is:

2*(225*(60/100)/25.4) + 14 = 24.6 inches

 

You can play with other sizes to find a width, series and wheel diameter that would have the same (close) diameter.

 

Hope this helps,

 

 

------------------

Pete Paraska - 73 540Z - Marathon Z Project - pparaska@tidalwave.net">pparaska@tidalwave.net -

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John, documentation says a 79 280ZX GL should have a 3.70 R-200.

 

280ZX 79 MT,4 Spd,2 Seater (3.364) (R180)

 

280ZX 79 MT,5 Spd,2 Seater (3.364) (R180)

 

280ZX 79 All With Automatic(3.545) (R180)

 

280ZX 79 MT,4 Spd,4 Seater (3.364) (R200)

 

280ZX 79 MT,5 Spd,4 Seater (3.7) (R200)

 

280ZX-GL 79 (3.7) (R200)

 

Scottie

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Welcome to the group John,

I too have both interests in auto crossing and drag racing (although all my auto-X friends seem to condone my 1320 addiction). I am currently setup with a 700R4 in front of a 3.54 R200 open diff. Because of the nature with Independent rear suspension, I have no problems keeping both tires lit in the water box. Also, during an auto cross, I never really “stab it†out of many corners (gets me in trouble). Bottom line, I don’t think I really need a limited slip.

 

But… (everyone always has a big butt)

I am starting to seriously think about swapping in an LSD 3.7 R200 from a 1st gen. 300ZXT. During my last few trips to the drag strip, my friend commented on my launch. He noted that my 30-60 foot time looked as quick as a 10 second car. However, my 0-30 looked about par for a mid 12 second car. Basically, he said I need more converter. I agreed, but (again… another big butt) I can’t find a lock up converter with more stall than 3000rpm… which is what I already got. The next logical item would be to replace the rear gear. With the current 3.54 ratio, I turn about 90mph at 3000rpm with fourth gear locked up. My rear tire is a 245/60/R14. Yeah, it’s too big for the rim, but I need money before I can do anything about it . Anyway, the 3.54 ratio has worked great for me. I’m just getting anal about my launches and I’m trying to muster every little bit out of the old girl as cheap as possible (hence the 3.7 bone yard swap).

 

Check some of the older posts, I’ve written a few messages with some of my 700R4 info (OK, ramblings). I’ve said this before and I will say it again… think about a new converter. These Z cars are too light to efficiently create the stall speeds seen in heavier vehicles. It’s pricey, but the best thing I have ever done for the car. Well, besides putting the squeeze on… 

 

Good luck,

-Andy

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I wish I'd known about the effort to get a group buy together. I need an LSD and if someone could've offered a complete ready to roll unit at a decent price I'd have been all over it. $1100 + rear + gears is waaay out of the realm of sanity.

 

Pete I'd be interested in the LSD you mentioned, I've tried searching here to no avail tho'. An LSD out of a first gen 300ZX may be what I wind up with - IF I can find one. I don't even spot them on the street around here (sigh).

 

Hee's another source for tire sizing -> http://www.powerdog.com/tiresize.cgi

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Guest Anonymous

Sorry, I've been so busy as of late that I've been neglecting my web surfing... wink.gif

 

If I have time, today I will call Reider Racing about a volume discount on those differentials. Would there be enough interest for a group purchase?

 

They have both R200 and R180 models. They're both more than $400, though. Still less than $600.

 

Reider has a website, but that particular Brute Force isn't listed. They definitely have them, though.

 

 

 

------------------

Michael Sen-Roy

Houston Performance

281-893-6080

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Honestly? I'm figuring I might have to spend as much as $500 for an LSD R200! Does Reider sell just the LSD or do they sell entire diffs? Just need to figure out what I'd need in addition to anything I get from them. Looking for as close to turn-key bolt-in as possible. I'm learning about the Z as I go and I'd prefer to break as little as possible along the way :-) Any info you turn up would be appreciated!

 

Anyone else interested in an LSD diff? I believe these are probably stronger than wrecking yard diffs if setup correctly!

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Guest Anonymous

I did call today, but was not able to talk to the person who can give volume discounts. I will try again tomorrow.

 

This is just the differential carrier. The carrier is the part the ring gear bolts to, and which houses the spider/side gears along with the clutch packs.

 

If you need a complete rearend, you'll need to shop the junkyards, then install the LSD carrier into the center section. While you're at it, new bearings for the pinion would be nice.

 

 

 

------------------

Michael Sen-Roy

Houston Performance

281-893-6080

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Count me in on a group buy! I still need to pick up a R200 from my local Nissan Wrecking yard, (they're about $200 here non-LSD). Factory LSD's are about as rare as 15 yr. old virgins out here. I've got a feeling that it's not going to be cheap anyway I go. If money was no object, I'd install a IRS unit from Concours West Industies. They have Jag, 9" Ford and Quickchange units up to 750HP! For those who have BIG Bucks or like to dream check them out at: www.cwiinc.com/

 

------------------

 

 

[This message has been edited by Z-Dreamer (edited July 11, 2000).]

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Guest Anonymous

I have the pricing information for the Power Brutes. I'm awaiting "official" permission to post about a possible group purchase. If you can't wait (like me!), shoot me an email in the meantime.

 

 

 

------------------

Michael Sen-Roy

Houston Performance

281-893-6080

------------------

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Guest Anonymous

Check out my post in the announcements forum.

 

 

 

------------------

Michael Sen-Roy

Houston Performance

281-893-6080

------------------

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