Speedos and rear ends

jeffball610 · Post by **jeffball610** » Wed Mar 14, 2007 8:10 pm

I know I'm getting ahead of myself here, but I want to be prepared. I'm running an R154 and have a couple options on rear end gears. What gear size should I shoot for with this tranny on the 4G63? I'll be doing quite a bit of highway driving, so I'd like something friendly to that. Also, how the hell am I going to run a speedo on this thing? I think the R154 has an electronic outlet for it, but how do aftermarket speedos work? Like the Autometer unit or something. I know I need to compensate for tranny gear, rear end gear and tire size. Let me know what anyone comes up with.

peregrine · Post by **peregrine** » Thu Mar 15, 2007 11:58 am

jeffball610 wrote:I know I'm getting ahead of myself here, but I want to be prepared. I'm running an R154 and have a couple options on rear end gears. What gear size should I shoot for with this tranny on the 4G63? I'll be doing quite a bit of highway driving, so I'd like something friendly to that. Also, how the hell am I going to run a speedo on this thing? I think the R154 has an electronic outlet for it, but how do aftermarket speedos work? Like the Autometer unit or something. I know I need to compensate for tranny gear, rear end gear and tire size. Let me know what anyone comes up with.

wed need to know your rpm goals on the freeway, tire size, 60 ft goals etc. the stock gear ratio of an awd dsm is 4.93:1 FYI.

jeffball610 · Post by **jeffball610** » Fri Mar 16, 2007 4:47 pm

It's kinda hard to set some of my goals, cause some of this stuff I'm still trying to figure out. I'd like to run a 235/35/16. I'd like to get something wider, but don't know if I can get more tire under it. On the highway, I'd like to run under 3kRPMs at 65mph. Not unreasonable. 60ft isn't something I'm too worried about. I will be drag racing some, but with the tire size I have to run, I'm more worried about just getting off the line and not spinning for half the track. I'm only looking to run about 300whp on the street and hopefully closer to 400whp for track days. I still can't find a site that has the R154 gear ratios. I'll try to find the ratios for the R200 rear end. I know the R160 comes in 3.7, 3.9 and 4.11 I think. I'll find out what I can. I think there's a calculator that does all of this for us isn't there. But I still need to know how to find out how fast I'm going on the speedo. I know I could figure out the RPM and then turn that into road speed. But how do I need to setup an aftermarket speedo?

Bill Hincher · Post by **Bill Hincher** » Fri Mar 16, 2007 5:21 pm

Hi jeff, here is the site for all the calculaters
http://www.bgsoflex.com/auto.html

as far as tires go, you cant beat Yokahama's, get soft compound tire and you dont need it too wide, they grip, mannnnnnnnn do they grip

jeffball610 · Post by **jeffball610** » Fri Mar 16, 2007 5:25 pm

Here's what I found on a quick search:

R154
1st 3.25
2nd 1.955
3rd 1.31
4th 1
5th .753

The R200 came in four ratios and a couple different LSD options. 3.364, 3.545, 3.7, and 3.9. It looks like the one I want is the 4/87+ 3.7 CLSD (clutch limited slip differental) in the 87-89 300ZX Turbo. I'll check out Bill's calculator and see what I can get.

I need about a 20" overall tire/wheel to get 3044RPMs at 60mph.

Post by **DJpowerHaus** » Fri Mar 16, 2007 8:43 pm

I always liked my Excel based calculator:

http://projectzerog.com/files/gearRatioCalculator.xls

carguyf545 · Post by **carguyf545** » Fri Mar 16, 2007 11:50 pm

i like 3000 rpm at 70 mph. but thats for my stock escort. with 300 whp i think 2500rpm at 70 mph would be nice. but thats just me, and if you are going to the track, change the gears. at one time i looked into getting another rear end and 4.66 gears for the track. i think it will take 1 hour max(after you have done it 6 or so times). but i got way ahead of myself.

F.Y.I. im selling everything sunday, or monday.(last chance DJ)

peregrine · Post by **peregrine** » Sat Mar 17, 2007 12:29 am

carguyf545 wrote:i like 3000 rpm at 70 mph. but thats for my stock escort. with 300 whp i think 2500rpm at 70 mph would be nice. but thats just me, and if you are going to the track, change the gears. at one time i looked into getting another rear end and 4.66 gears for the track. i think it will take 1 hour max(after you have done it 6 or so times). but i got way ahead of myself.

F.Y.I. im selling everything sunday, or monday.(last chance DJ)

do i still have dibs on the colt? (say yes)

carguyf545 · Post by **carguyf545** » Sat Mar 17, 2007 1:12 am

you just need to come and get it, i can take pics tomorrow, if you post tonight.

peregrine · Post by **peregrine** » Sat Mar 17, 2007 1:38 pm

carguyf545 wrote:you just need to come and get it, i can take pics tomorrow, if you post tonight.

yeah ill come and get it. that would be pretty fun i think. ROAD TRIP!!!!

post some more pics please.

Bill Hincher · Post by **Bill Hincher** » Sun Mar 18, 2007 10:24 am

I knowwwwwwwwwwwwwwwwwwww this is a dumb idea jeff,
But I always wanted to have some fun with the dashboard and the instruments. As important as it i to know the altitude/air peressure to a performance car and with the complexity of your speedometer change over why not consider an air speed indicater?
Yeah, I know they aint exact and yeah they only measure what is relitive to the vehicle speed.

But it would be sooooooooo cool to have an airplane dash laid out , and the stuff aint that expensive in ultra lite aircraft supply places
http://www.aircraftspruce.com/menus/in/ ... ators.html

other then that , we can look for a suitable drive unit in te trans that will drive a speedo cable and then find the ratio box that would set you up or we could look into a front wheel drive system like the VW bugs

peregrine · Post by **peregrine** » Sun Mar 18, 2007 6:58 pm

yeah i might do the same. it would be real easy to do an aftermarket speedo with my th-350 i think.

Bill Hincher · Post by **Bill Hincher** » Sun Mar 18, 2007 9:20 pm

The R-154 I got has the speedometer cable housing centered on a gear counter on the rear shaft, I dont think you could change it over to manual.
Even if you removed the tail shaft and put a gear on it, the hole for the cable drive gear is not offset enough.
I guess the best thing would be to find a good generic digital speedometer and use an adjustable adaptor, but thats money that could go somewhere else

jeffball610 · Post by **jeffball610** » Mon Mar 19, 2007 4:52 pm

I found this on Autometer's website. This is exactly what I was looking for. I was planning to use an Autometer setup anyway. I don't even need to do anything other than drive 2 accurate miles and wire the thing up. It SHOULD be that simple.

http://www.autometer.com/tech_faq.aspx?sid=2

Now I just need to find a tire/wheel size I like for my gearing. Well, first I need a rear end, but I can still plan ahead.

Bill Hincher · Post by **Bill Hincher** » Mon Mar 19, 2007 8:36 pm

I can only speak from a V-8 prospective, but on the street anything over a 3.25 ratio is geared too high, I run a 3.50 ocasionally and I tried to get away with a 3.89 ratio ONCE but it was in high gear at 30 mph.

for all around balance I stick with a 3.25, I would like to come up with a two speed splitter using a planetarty gear from a 4wd hi lo set up.

carguyf545 · Post by **carguyf545** » Mon Mar 19, 2007 9:48 pm

now your talking bill. i was thinking a np205(gear to gear heavy duty). maybe a guy could cut the front drive off to make it smaller. than just put a block off plate where you cut it. i can think how it can be done, i evern have access to that transfer case or many other styles. i just dont have time. so great idea. hope to see it done and mapped out, so i can copy it with ease.

peregrine · Post by **peregrine** » Mon Mar 19, 2007 11:03 pm

Bill Hincher wrote:I can only speak from a V-8 prospective, but on the street anything over a 3.25 ratio is geared too high, I run a 3.50 ocasionally and I tried to get away with a 3.89 ratio ONCE but it was in high gear at 30 mph.

for all around balance I stick with a 3.25, I would like to come up with a two speed splitter using a planetarty gear from a 4wd hi lo set up.

i run a 3.50 in my colt and it cruises on the freeway at around 3400 rpm. perfect i think.

Bill Hincher · Post by **Bill Hincher** » Mon Mar 19, 2007 11:46 pm

carguyf545 wrote:now your talking bill. i was thinking a np205(gear to gear heavy duty). maybe a guy could cut the front drive off to make it smaller. than just put a block off plate where you cut it. i can think how it can be done, i evern have access to that transfer case or many other styles. i just dont have time. so great idea. hope to see it done and mapped out, so i can copy it with ease.

You look at those RV two speed splitters and that is all they are, a 205 np blocked off and set up backwards, I saved one out of a GMC blazer just to see what I could do

carguyf545 · Post by **carguyf545** » Tue Mar 20, 2007 12:49 am

well get to work, chop chop. lol.

bill do you sleep, you must spend half the day online and the other half running your shop, building cool one off things and i cant wait to see that crx run.

jeffball610 · Post by **jeffball610** » Tue Mar 20, 2007 1:54 pm

With the 4G63, 3000rpms is about where you want it. That's where you start making power and when most turbos spool up. So when you're out on a highway, you can give it a little and go. If the rpms are even 500rpms lower, you have a little too much lag. You also have to look at the stock DSM. At 65mph I think I was running around 3000rpms. That was with a 225/35/17 tire. (that's about stock) And on a stock DSM with no head work, you can still run at least 145mph. I know a guy that had a bad ass 2G that shifted to 4th gear at 130mph.

Bill Hincher · Post by **Bill Hincher** » Tue Mar 20, 2007 8:57 pm

will the REAL Jeff Ball please stand up???????????????????????

wow, your getting your ' stuff' together. You been playing possum out there in the mountains

veryyyyyyy cool

better get a roll bar in it if your gonna shift up @ 145mph

carguyf545 · Post by **carguyf545** » Tue Mar 20, 2007 9:03 pm

i would gear it up for gas mileages. just cruiseing on the free way. my talon is geared way to low for what i want. how lond do you think it would take to spool at 2500 in a 350whp 2.0 or a 2.4? what about 1.5 seconds longer.

Bill Hincher · Post by **Bill Hincher** » Tue Mar 20, 2007 9:23 pm

carguyf545 wrote:well get to work, chop chop. lol.

bill do you sleep, you must spend half the day online and the other half running your shop, building cool one off things and i cant wait to see that crx run.

Its all about stuff Carguy, Hot Rodding aint supposed to be about how much money you can spend, its about finding stuff and making your own car.

Anybody can make payments...........but only a handful of us can build/drive our own creations

I am under ' supervision' on the sleep disorder thing, I havent been the same since I lost my job as a ' greeter' at the 'free' clinic

peregrine · Post by **peregrine** » Tue Mar 20, 2007 11:00 pm

carguyf545 wrote:i would gear it up for gas mileages. just cruiseing on the free way. my talon is geared way to low for what i want. how lond do you think it would take to spool at 2500 in a 350whp 2.0 or a 2.4? what about 1.5 seconds longer.

im not sure why you keep mentioning spool and horsepower in the same sentence more or less power wont affect your spool at all.

carguyf545 · Post by **carguyf545** » Tue Mar 20, 2007 11:31 pm

well in most cases big hp is caused by big turbos. big turbos normaly take longer and/or more rpm to spool.

peregrine · Post by **peregrine** » Wed Mar 21, 2007 12:01 am

carguyf545 wrote:well in most cases big hp is caused by big turbos. big turbos normaly take longer and/or more rpm to spool.

ok i see. it would behoove you to mention the turbo instead of the power then. ive seen guys with 60-1s making 250 horses

carguyf545 · Post by **carguyf545** » Wed Mar 21, 2007 10:55 pm

lol, sorry for not being more descriptive, but i forgot there are stupid ppl. out there. i took it forgranted that smart ppl size there turbos to there power goals.

i have seen huge turbos on civics that push 8 psi and spool a 4500. lol.

jeffball610 · Post by **jeffball610** » Thu Mar 22, 2007 5:41 pm

I don't plan to run an extreme setup on my Datsun. I'm using a stock 2G botom end (for now) and basically stock 1G head. These have been proven to handle 350hp+ without issue. Even with stock valve springs I should be able to rev to 7500rpm without issues. I'm running the SBR GT11 and it should spool well enough to make 15psi around 3k-3500 rpms. (i hope) If not, then I'll get a smaller turbo, but this should be no problem. As far as highway cruising, most DSM guys don't mind running 3k rpms @65mph and getting 30mpg.

I got a lot of abreviations in there didn't I?

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Speedos and rear ends

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