Based on the numbers I've seen, more than you would think. 1/16" is tiny if you're measuring distance, but adding 1/16" or 1/8" in diameter ... you're talking about significant double digit increases in the percentage of area increase.

This is a really good read and he shows the math ...

4x4Wire - BRAKE UPGRADES

What I expected based on his math is exactly what I ended up with. His calculations seem to be pretty dang accurate. Its pretty easy to figure out what you have now, and what you'd end up with if its not on his chart.

In my experience there's very little room between crap and awesome brakes and its really blurry in the middle. Yes, there's wiggle in that a change 1/16" one way or the other won't result in totally inoperable brakes, but there's very little wiggle between 'ok' brakes and optimally operating brakes. Which makes sense. You need to move as much fluid as you need to move. Its just physics. Its not subject to interpretation.



I haven't messed with boosters and only a little on non-Mitsu stuff. My experience is that getting the BMC volume and the calliper volume matched up makes a MUCH bigger difference than fiddling with the booster. The booster only does one thing and its function doesn't depend on the BMC or callipers. Its just a multiplier.

Going with the bigger Hilux booster would probably make a difference. It would probably make your brakes more sensitive - it would take less pressure on the pedal. Maybe a lot less - it is possible to go too far. My mom's '70 SS Nova has brakes that are so sensitive I think they're actually dangerous.

Knowing what I know now, I'd get my BMC and calipers matched up first. Then I'd see if the amount of pressure required on the pedal was where I wanted it. You DO NOT want a super sensitive brake on the trail. That is major suck. If you needed a little more multiplication, in your case, I'd look at the pedal since changing out the booster isn't practical.

But, I'd make sure the BMC and callipers match first. It could turn out that fixing those makes such a huge difference that everything else is fine as it is. Like mine now, I see absolutely no reason to mess with the booster or pedal where before the swap a couple months ago, I was thinking of looking for a larger booster.

Edward

Christmas is coming early this year!

Teraflex Extreme Short Shaft SYE
Teraflex Low231 4:1 Transfer Case Kit - Short 23 Spline
Output yoke - 32 spline Spicer CV output yoke 1310

NWF Eco Box crawl box kit
Output Shaft:: 23 Spline
Input Bearing Retainer: Dual Oiling Billet Bearing Retainer
Crossmember Mounting Foot:: Universal Mount

Dakota Digital Universal Speedometer Signal Interface Controller SGI-5 C

4Crawler.com 2" body lift HD10 + EH

25' steel brake line
SAE & Metric flare nuts
Wilwood adjustable proportioning valve 260-11179
3000GT VR4 w/ABS 1 1/16" brake master cylinder

Pending:
PCS TCU & harness
Radesigns' A/T shifter
Transgo shift kit
Transfer case & crawl box shifters


Local guys here in Denver that do my M/T rebuilds are going to supply all the t-case parts and build the transfer case so I don't end up with a bunch of useless extra parts from the SYE and Low231 conversion - like I did the last go-around. They're also going to supply the internals (six gear planetary, etc.) for the crawl box.

Once I get the shift kit in, the AW4 and associated parts go to the transmission shop to have the pieces installed and the transmission freshened up. Next month.

In the meantime, I'm going to do the ABS delete, master cylinder swap, proportioning valve install, intake and air tube install and the Contour electric engine cooling fan assembly. I'm also going to do the electrical install - junction block, 4AWG cables, replace the OEM negative cable with 4AWG, etc. BEFORE I start installing all the accessories. If I get real industrious I may install the ARB on-board air while I'm at it.

Then it'll be time to install the AW4, transfer case, crawl box, SGI-5 and TCU. Actually, by then it'll probably be time to head out to Moab.

Edward

RADesigns Products, LLC

Transgo 340-HD2 shift improver kits for AW4 and A340
Switch Kits-includes two Carling switches
A340/AW4-Winters Shifter #607-1 & Switch Kit Option
Modified Gate to a Rock Gate style


If this stuff works half as good as Rory's customer service I'll probably go into a coma. There aren't many places that give me reason to brag up their customer service, but dealing with Rory is great! Clear emails, speedy response and even answers his phone! Quite refreshing after dealing with NFW. :rolleyes:

Anyway ... got all this ordered. All that's left is the PCS TCU. The Transgo kit was a little cheaper elsewhere but I'd rather give my money to Rory.

Its going to be interesting putting all this together. This is going to be a much bigger project than my original M/T adapter and doubler project.

Edward

thats some serious reduction if you have 4.1 gears in the 231 plus the NWF box.

Mine is just over 100.1 in low low, yours will be around 50% lower again!. Why do you need such big reduction?

Sigh. I spoke with a fab shop on Friday. Guy I've wheeled with before. He had the same question. I have a driveability quandary and what I want is conflicting with what typically makes sense.

This isn't going to be a trailer queen. First problem. I have to be able to drive it to Moab from Denver which means a minimum two 11,000-12,000 ft passes. That means road gearing in the axles that will accommodate 6,000-7,000 GVW at highway speeds (45-75 MPH). With 37" tires I need to run at least 5.13s. The math says I should be running a 5.8:1 axle gear to get back to 'factory' but that's not going to happen in a Dana 44.

I WANT a three speed reduction. Which is problem #2. In order get that and keep weight down, I'm limited to the NP231 platform and gear ratios and the only ratios are 4:1 and 2.72:1. I primarily use 2.72 and 4:1. However, I have a lot more gear choices with a 5-speed M/T in each range than I will have with a 4-speed A/T. I can use all five gears in the M/T, but my understanding is that you shouldn't use 4th in the A/T so effectively I'm down to a 3-speed. More of my 'fine tuning' of ratios on the trail will be handled by the transfer case and reduction box than it currently is with the manual transmission so an extra range ratio will be very handy.

Problem #3 is this is going to be a HEAVY vehicle. I don't have any practical way to combat that. Its not just heavy, its top heavy. I'm hoping to lower CG a couple inches and widen the wheel base maybe another 1.5-2" but I expect that will get the '99 loaded back to where the '97 is unloaded. I'm good with that IF I have the option of super low snail crawl. My '97 is and this will be a lot more capable if I can control the body movement - which I can't do if gearing is so tall that I'm bouncing all over the place.

On the trail, I think anywhere between the 4.20s and 4.63s would be good, but there's no way I could get it to move on the highway in town, let alone running up a 8-12% grade at 11,000+ ft, automatic transmission or not.

I'm making some 'educated' trade-offs. What I'm trying to build is an 'expedition crawler'. Basically an advanced version of my '97. Something that will do trails like Pritchett Canyon, Flat Iron Mesa, etc. in Moab while being able to put on 2000+ miles of highway and county roads in a trip. So, get the axle gears down for the highway while compensating for the taller tires and A/T gears with the t-case and crawl box.


Mitsu V5MT1 M/T transmission ratios:
First Gear Ratio: 3.918
Second Gear Ratio: 2.261
Third Gear Ratio: 1.395
Fourth Gear Ratio: 1.000
Fifth Gear Ratio: 0.829

Crawl ratio 2.72 & 5.38:
1st: 57.2:1
2nd: 33:1
3rd: 20.3:1

Crawl ratio 4 & 5.38:
1st: 84:1
2nd: 48.6:1
3rd: 30:1

Crawl ratio 10.88 & 5.38:
1st: 229:1
2nd: 132.3:1
3rd: 81.4:1

(I didn't bother with 4th both to make this easier to read and because I rarely use it on the trail)


Mitsu 'AW4' A/T transmission ratios:
First Gear Ratio: 2.804
Second Gear Ratio: 1.531
Third Gear Ratio: 1.000
Fourth Gear Ratio: 0.754

Crawl ratio 2.72 & 5.13:
1st: 39:1
2nd: 21.3:1
3rd: 14:1

Crawl ratio 4 & 5.13:
1st: 57.4:1
2nd: 31.4:1
3rd: 20.5:1

Crawl ratio 10.88 & 5.13
1st: 156.3:1
2nd: 85.4:1
3rd: 55.8:1


Crawl speed '97 - '99 (in/sec @1500RPM):
2.72:1
1st: 47 - 74
2nd: 81 - 136
3rd: 132 - 208

4:1
1st: 32 - 50
2nd: 55 - 92
3rd: 90 - 141

10.88:1
1st: 11 - 18
2nd: 20 - 34
3rd: 33 - 52

(All the math above was done without calculating in torque converter slippage - just straight mechanical ratios)


I wheeled with CoSport a lot back in the day when he was running 35"s on his '98 'narrow' Sport with 4.20s in the axles and the 'AW4', and I've driven my '97 in various gearing configurations for 17 years, so here are some educated assumptions...

The commonly accepted multiplication ratio for the torque converter is - roughly - 2:1.

#1: The deeper the gearing - this is the total of axle, transfer case and crawl box - the less slippage (multiplication) you get out of the torque converter.

#2: The more GVW, the more slippage (multiplication) there will be in the torque converter.

#3: The larger the tire - both in diameter and width - the more slippage (multiplication) there will be in the torque converter.

#4: A larger diameter tire decreases the final gear ratio at the ground (effectively like installing taller - lower numerically - gears).

I'll stop here to keep this simple and leave out the 'minor', really variable variables.

If I do the math on the crawl ratios and crawl speeds, I'm looking at an average of about a 38% decrease in crawl ratio and a 48% increase in speed from my '97 to the new '99.

2:1 is a very rough number and not particularly precise but its what I'm working from. The lower the stall converter the lower the ratio and the lower the resistance placed against the T/C the lower the ratio. Given the reasonably tight factory T/C, the drop to 5.13s in the axles, with the increase in tire size and vehicle weight, my educated guess is that 1.5-1.6 is probably closer. So, if that's the case then calculating in the T/C should get me effective ratios that are on average reasonably close to my '97.

Of course, this is all conjecture because every time you go up or down a hill or add 100 lbs or take 100 lbs out, all the math goes straight to hell. What I'm shooting for is a flat ground, reasonably close approximation of my '97 which I'm reasonably confident this configuration should give me.

A good thing about T/Cs is a change to GVW and/or terrain changes the multiplication. When loaded out for Moab, the 'gear ratio' will be deeper - which is good. Same for steep technical climbing. Under light load and more mild, even terrain the 'ratios' will be taller - which means better fuel mileage. I hope.


Actually, the '99 will only be about 44% deeper than yours. I know that sounds like a lot, but I'm not sure its going to be in practice once the '99 is done.

The '99 will come in close to 6300-6400 lbs GVW in DD mode with the ProRocks, rear steel bumper/tire carrier, torque bar and 37"s, and I'm pretty sure the A/T weights more than my M/T, too. I typically have between 600-700 lbs of extra weight when we go out to UT or camping. Figure hauling all that weight @ 4,000-14,000 ft altitude both on and off road.

I may be way off and it may be too much gearing. I don't know for sure. I don't think so based on my '97 but I guess I'll find out.

Edward

Ok I see.

Just for info, oh the auto, 4th is locked out (somehow) when in 4wd lo

Yep. Both the Gen 1 and Gen 2 if I remember correctly. I'll be using Rory's full manual Winter's shifter so in theory I could have access to all four gears in anything including T/C lock in any gear.

What I've been told is "DON'T DO THAT!" 1-3, is ok. NO T/C lock on the trail.

On the highway, I'll be running the PCS TCU. Nothing Mitsu will be controlling the A/T.

Edward

Ed,

35 & 37 tyres are huge, are you changing the front end. Folks generally say that 33s are the limit with the Paj IFS. Oh btw got my new front shaft from Tom Woods, great no vibes very happy!!! I pulled the old one apart , the splines were worn at the slip joint, too much play that must have been the cause of the vibes.

Got the 2" body lift ordered yesterday night from 4Crawler. I have to give them points for responsiveness! Less than a 1 day turnaround to get all the info I needed.

D12+HD12+EH

It ended up being about $160 with shipping, etc. I wanted a couple extra pieces so I got the 12 instead of the 10 and the extra long hardware. I especially wanted the Grade 8 hardware since this is going to get a lot of wear and tear off road.

Edward

I'm not planning on running IFS. My '97 already has a SAS with D44s & 35"s. Well aware of how big a 37" is. This build will also get a solid axle conversion, but will be running a 3-link up front and leaf springs in the rear with Dynatrac ProRock 44s front and rear.

Dynatrac ProRock 44Ö

Trying to decide if I can justify this ...

Dynatrac ProRock 44/60 HybridÖ

I'm not up to posting the suspension stuff yet. I'm trying to get all the stuff I need to do before it goes to the shop for the SAS up. That is a LOT of stuff. I have an appointment with the shop the 2nd of January to go over everything and get the ball rolling. I was worried about not being able to do the 3-link but we may have that figured out. With the 2" body lift we may be able to raise the engine and transmission 1-2" to clear the upper link. Keeping my fingers crossed!

Cool!! Good to hear! Yea, been there. That's how I could tell it was time to replace the slip yoke on my '97 back before the SYE. Good that fixed things, though!

Edward