95' Junker Drag Truck

My solution to less reciprocating mass is to skimp on Breakfast... This year you may get banned from the May Madness Dyno for proving an inevitable truth...
 
Big Blue24 said:
Mild Tranny Carnage

I pulled the transmission last night (3 hours) I know I'm slow but to pull the tranny on my race truck there are a few extra steps: prop the truck up 18" so there is room to work under there, remove 90% of the twin turbo setup, remove the relocated transmission heat exchanger, remove both driveshaft loops, remove the homebuilt 5" exhaust system....

Anyway, my diagnosis was correct, the forward clutch pack was burned up. I created an experimental setup last time for this clutch pack and that's probably 90% of the reason for failure. The experimental clutch pack involved removing the plastic cushion spacer, installing two belleville springs instead of one, stock pressure plate, 4 clutches and 5 steels, flipped over pressure plate instead of stock .280" thick flat reaction plate, stock waved snap ring. The first thing I noticed is that the 4th clutch was just barely catching the splines on the ring gear and so it basically wasn't engaged, so right away I had a 3-clutch pack instead of 4. It also looks like the belleville springs flexed far enough to make contact with the planetary that mounts on the end of the intermediate shaft.

In this case a picture is worth a thousand words since I'm sure the above description is foggy at best:

Transmission01.jpg


Transmission02.jpg


Transmission03.jpg


Transmission04.jpg


Transmission05.jpg


Transmission06.jpg


Transmission07.jpg


Transmission08.jpg


Transmission09.jpg


Transmission10.jpg


Transmission11.jpg


Transmission12.jpg


Transmission13.jpg
Click to expand...

I have same problem in my 47RH that I have rebuild in June/July 2012...
...hey, how did you get the tranny to shift at higher then 3000rpm?
Shaved down some of the governor weights? Mind sharing? How much weight, where, pix, etc...? I have hard time finding any brass/steel governor weights or any info on the subject...
:bang
 
Last edited:
WHAAAAT??? I just read 70 pages of build :pop: and the truck's still apart???? :hehe:

Blue, thank-you for sharing your project, modifications, ideas, insights, research and knowledge. What an inspiration! I guess it doesn't have to take a million dollars to have fun with some real power at the race track! I've read this entire thread page by page and am quite impressed with your ability to source "cheap" parts and stick with the "junker" theme, even amidst others egging you on to spend spend spend. I love how you push everything to the actual breaking point before replacing. That said, you seem to also have an uncanny ability to get away with modifications that most of us simply don't get a way with - like running 70+psi on over-torques head bolts for how many passes?? or running 40+ psi on the small turbos. I'm truly impressed with your steady, careful work and very grateful for the opportunity to learn from your build. I love the in-depth explanations that actually teach good useable info and keep it comin' with the GREAT pics!!!

Thanks to all you other fella's for your input as well! Keep up the good work. Ok, I'm done. As you were....
 
diesel_ said:
I have same problem in my 47RH that I have rebuild in June/July 2012...
...hey, how did you get the tranny to shift at higher then 3000rpm?
Shaved down some of the governor weights? Mind sharing? How much weight, where, pix, etc...? I have hard time finding any brass/steel governor weights or any info on the subject...
:bang
Click to expand...


To raise the shift point, I used a combination of 3 modifications. Any one of these modifications can be used to raise shift points but I ended up doing all three before I had the valvebody setup to shift where I wanted it with the gear selector in "D" so I could worry about racing and not hitting shift points.

1. Lighten the brass governor weights, I used a 1/8" drill bit and removed about 6 holes 1/2" deep. I didn't weigh the weights before and after but this raised all shift points about 150 rpm.

2. Add another spring inside the throttle valve spring. TV pressure counteracts governor pressure so a stronger spring means more opposing line pressure to counteract the upshift pressure coming from the governor. I played with the springs in this quite a bit because it's easy to change when the valvebody is removed. I don't know the size of spring or how many are in there now but this changed the shift point anywhere from 50-300 rpm depending on spring pressure. One advantage of modifying the spring in the TV assembly is the TV lever can be externally adjusted to fine-tune the changes you made internally.

3. Add/modify the 1-2 and 2-3 shift springs. Inside the valvebody, there is a valve that controls the 1-2 shift, and a separate valve for the 2-3 shift. There is a spring holding the valve in the lower gear, tv pressures is fed to the spring side holding the valve in the lower gear, and governor pressure is fed to the opposite side of the valve trying to force it toward the higher gear circuit. A stronger spring raises the shift point of that single gear shift. On my tranny, I increased spring pressure with a dual spring setup to get the 1-2 gear shift around 2900-3000 rpm. I like to get the truck into second gear as soon as it's fully spooled and near peak power so lockup will be engaged early in the run. I then added even more spring pressure on the 2-3 shift valve to make that gear shift closer to 3300-3400 rpm. This gear shift is brutal on the drive train and usually breaks traction on everything but true drag slicks. The more I raised this shift point, the faster the truck went because higher rpm meant higher ground speed and more chance for traction. Overdrive is electronically controlled on a switch, 2600-2800 rpm seemed to result in the fastest MPH and lowest ET on this truck. Later 3000+ rpm overdrive shifts always resulted in slower times.


If I were in your shoes, I'd research the weight difference between brass and aluminum, research the normal WOT shift rpm for V-10 trucks equipped with aluminum weights, and lighten the governor weights to some percentage between stock brass and aluminum weight depending on desired shift point. Then I'd play with the TV springs if you want more total rpm on all shifts or play with the individual shift valve springs if you want to fine tune the individual shift characteristics of a certain gear shift.
 
I just finished reading this whole thing and wow I am impressed! definitely made a few notes for myself thanks for taking the time to do such a good write-up and thanks to everyone else who chimed in now i'm hooked i cant wait for the next update!
I liked the idea of pushing compressed air to help the turbo light faster, if it's feasible. wired up to a push button like how the ricers have for nos might not look so bad
 
97extcab said:
I just finished reading this whole thing and wow I am impressed! definitely made a few notes for myself thanks for taking the time to do such a good write-up and thanks to everyone else who chimed in now i'm hooked i cant wait for the next update!
I liked the idea of pushing compressed air to help the turbo light faster, if it's feasible. wired up to a push button like how the ricers have for nos might not look so bad
Click to expand...

Bendix actually has a system in place. I have driven on of their trucks with it and was impressed. Maybe look up their system for ideas.
 
Really nice job with the truck. mind me asking what you did with the overflow line from the injectors that ran back to stock filter housing? im building my fuel system now and unsure on my options
 
BLT4SIN said:
Really nice job with the truck. mind me asking what you did with the overflow line from the injectors that ran back to stock filter housing? im building my fuel system now and unsure on my options
Click to expand...

Just make a Tee into the return line.
 
BLT4SIN said:
Really nice job with the truck. mind me asking what you did with the overflow line from the injectors that ran back to stock filter housing? im building my fuel system now and unsure on my options
Click to expand...

I also Tee'd it:

7515E7F3-27B9-41F5-854E-3233E56DE232-5380-000007EA98DD6628.jpg


4EDE94F8-4A49-4DCF-93CD-AEF0D7DFE440-5380-000007EA8FC1A68C.jpg



Misspelling courtesy of my fat fingers...
 
^ i did the same, but i tapped a hex female-female NPT adaptor to 8mm just like airdog supplies in their kits
 
Hold your horses, I'm working on it every free minute I get. The Junker Drag Truck hasn't been to the track for almost 1 year now I'm getting antsy......

The new roll cage needs to be installed....
The fuel cell...
The 215 pump...
The 5x.025" injectors...
The ported head...
ETC......
 
No more budget? Also are you doing the mods one at a time to see performance difference
 
You must log in or register to reply here.
Back
Top