4.10s or 4.30s? Parts list...

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djKale

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I'm looking at doing a rear end swap on my Mark VIII and I need to get a list of everything I will need, special gear olis, speedo adapters, misc. bolts, chip retune, etc. I want to buy a complete third member and swap it out. I'm gonna have a local shop install the gears.

I'm also torn between 4.10s or 4.30s. Leaning towards the 4.30s right now. Would appreciate opinions on each.

And I know I may end up needing a Metal Matrix Driveshaft, but I want to see how it drives before I buy one.

Geno, Chris, you guys listening??? Hook me UP!

Kale
 
4.30s without a doubt.
Especially with your recent purchase.They took my 3.55s all the way back to 3.08s.It will take your 4.30s all the way back to 3.80-3.90ish and you could probably get away without a driveshaft and you might be able to use the 3.73 speedo gear.

Hit me up if you need more info.
 
What are your driving habits? I would hate to be doing alot of highway miles with some 4.30's whining away. That is where I would start first. Then I would ask myself, do I want a killer 0-60 car, especially a 4000 lb'er, or do I want a qtr mile king? I you are looking for some top end, I would probably stay with the 3:73's you get with the new center section. Just a few thoughts.
 
unstoppable said:
4.30s without a doubt.
Especially with your recent purchase.They took my 3.55s all the way back to 3.08s.It will take your 4.30s all the way back to 3.80-3.90ish and you could probably get away without a driveshaft and you might be able to use the 3.73 speedo gear.

Hit me up if you need more info.
Click to expand...


Ok Kale
You guys have peaked my interest ...You are building what ?? come on spill the beans.... Must be tires , that recent purchase, and anything that tall must be slicks ??? Are we building a monster ?

:ttiwwp:
 
Kale I dont think it was ment to be a secret as you have posted other places but I'll give a hint just in case.

245/40-20 BFG KDWs

They measure a hair over 1 inch taller than stock if I remember correctly.
 
Ya, no secrets here, I bought Chris' old wheels from 94hondakiller (aka Joe) on LOD. They look crazy in person and ride great, not anything near what I had expected. I tried putting a 275 out back, but the 245s are already rubbing when the car is slammed. I'm gonna be modding the suspension a bit to get it to go lower up front and out back. Here's a pic since this thread is useless without one:

my_mark_on_20s.jpg


Ponyfreak (another Joe) said he will be selling another 4.30 rear end and that he'll give me "first dibs" on it. So that's the plan right now. I'm still curious about the speedo gear. I'll be contacting you Chris if/when I need more info.

Kale
 
Those look SICK! Kale. I SO wish I never sold them.
Just so you know Enkei only made that wheel in 20s.They wanted to make sure only gangstas like you could roll'em.You wont see them on any farking honduhs.
 
Very nice Kale ...I like them a lot ... Here is a chart that might help you out...Maybe it should be entered in the tech section..

SpxImage.JPG
 
I think that chart is for a 1:1 transmission ratio. If so, your RPM will be ~1/3 less than the listed value since the OD is .67 I believe.
 
JoshMcMadMac said:
I think that chart is for a 1:1 transmission ratio. If so, your RPM will be ~1/3 less than the listed value since the OD is .67 I believe.
Click to expand...


Yeah, I was wondering about that myself.
 
The ratio on the 4R70W is .70, at least that's the figure I found online. According the formula, I should be turning ~1600RPM at 60 right now. I measured my tire size as it sits on the car and it measures almost 27" exactly. I'm running ~1900RPM@60MPH right now, IF my speedo and tach are correct, which they probably aren't. I'm gonna break out the GPS today to verify my speedo.

Even with 4.56s out back, I should still only be turning 2400 RPM...((60*4.56*336/27)*.70) = 2383.

Kale
 
djKale said:
The ratio on the 4R70W is .70, at least that's the figure I found online.
Click to expand...
That is what I found as well. The AOD and some of the the AOD-E have a .67 OD ratio. The 93-95 VIII's have the AOD-E, but they are outfitted with the wide-ratio gearing with .7 as the OD ratio. Then the VIII's got the 4R70W with the same gearing. Good catch!
 
Last edited:
I threw that equation into Excel real quick and made up a chart that is more suited for your needs. It uses the equation listed above, but multiplied by the final drive ratio of 0.7 to more accurately reflect what a Mark VIII would do. I calculated the the speed as 60mph, as I think that is more accurate for typical highway speeds. That's excluding the peanut-gallery that breaks 100mph whenever they see a straight-away. ;) I also changed the highlighting, as I think cruising at 3000rpm is far from typical for cruising the highway. The blue section is 1700-2000rpm, which is pretty typical for stock at 60mph. Then the yellow is 2000-2300rpm, which is about where I personally would want to be if I had a set of gears. The pink is 2300-2600rpm, which is where I think you start getting into the less desirable rpm but still acceptable by most. I hope this helps.

tire%20diameter.JPG


http://www.freewebs.com/markviibullitt/Book1.htm
 
JoshMcMadMac said:
I threw that equation into Excel real quick and made up a chart that is more suited for your needs. It uses the equation listed above, but multiplied by the final drive ratio of 0.7 to more accurately reflect what a Mark VIII would do. I calculated the the speed as 60mph, as I think that is more accurate for typical highway speeds. That's excluding the peanut-gallery that breaks 100mph whenever they see a straight-away. ;) I also changed the highlighting, as I think cruising at 3000rpm is far from typical for cruising the highway. The blue section is 1700-2000rpm, which is pretty typical for stock at 60mph. Then the yellow is 2000-2300rpm, which is about where I personally would want to be if I had a set of gears. The pink is 2300-2600rpm, which is where I think you start getting into the less desirable rpm but still acceptable by most. I hope this helps.

tire%20diameter.JPG


http://www.freewebs.com/markviibullitt/Book1.htm
Click to expand...

Awesome spreadsheet! But one question for you.
Where do you find anybody doing 60mph on a highway? Most highways I drive are posted at 65mph and are being driven by most at closer to 70-75mph. It's funny when I find someone cruising on the highway in an older modded up car with a 4-speed stick, or a 3-speed auto. You can't get them to race because they're already near redline and have nowhere to go. They're all strickly 1/4 mile cars.
 
Katshot said:
Awesome spreadsheet! But one question for you.
Where do you find anybody doing 60mph on a highway? Most highways I drive are posted at 65mph and are being driven by most at closer to 70-75mph. It's funny when I find someone cruising on the highway in an older modded up car with a 4-speed stick, or a 3-speed auto. You can't get them to race because they're already near redline and have nowhere to go. They're all strickly 1/4 mile cars.
Click to expand...
I was going with what I would consider the "national average" for speed. Since the speed limit is often 55mph, I went with 5mph over. I am much like you, with most of my highway driving in a 65mph zone doing 70mph. But that is in western Maryland, whereas most anywhere on the beltway or towards civilization the speeds are set at 55mph.

But this is the beauty of the spreadsheet. ;) Here is a setup with 70mph.

*edit* - Please note that the colored regions are no longer accurate!

70MPH.jpg
 
Oh very clever ,my dear Watson..
I didn't think about the overdrive.... However one of these charts could be very handy for referance... Can somebody with a known gear ratio and tire diameter , verify the charts and which is correct ? I would but my tach doesn't work...You will need the proper wheel diameter to get the proper MPH and know your gear ratio...I would suspect Josh has the correct chart but I would like to verify...
 
Topcat said:
Oh very clever ,my dear Watson..
I didn't think about the overdrive.... However one of these charts could be very handy for referance... Can somebody with a known gear ratio and tire diameter , verify the charts and which is correct ? I would but my tach doesn't work...You will need the proper wheel diameter to get the proper MPH and know your gear ratio...I would suspect Josh has the correct chart but I would like to verify...
Click to expand...
It's not a matter of correctness. Your chart is right, it is just setup for a 1:1 transmission ratio. I just factored in the OD 0.7:1 ratio, and it works out. I checked it against a 96 Camaro, as the OD is 0.7 as well and it works out right. And with the spreadsheet you can adjust it for just about anything.
 
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