Cummins Diesel Forum banner

68rfe service and revmax VB install....

16K views 10 replies 4 participants last post by  wdimig 
#1 ·
Ok truck has approx. 118k on her now, did a trans. Service back at around 70k, getting ready to do another, but was thinking about adding a revmax valve body along with a new solenoid pack while in there to help keep things going a while longer, with the power level the truck is at, I know I'm on borrowed time, but honestly the stock trans. With tuning has been nearly flawless considering it's had roughly 440/950 @ the RW for the last 80k. Anyway, since I have multiple Snap-on scanners at my disposal, i took a look at the CVI values to see how healthy the trans. Is for the mileage it has on it currently, I couldn't really find a whole lot of CVI info. these are the values that I found maybe Revmax could chime in and suggest if adding a VB and new solenoid pack this late in the game would be worth it or not, anyway here are the CVI values I got off the scanner,
2C - 35
4C - 34
L/R - 64
OD - 51
UD - 50
Also had these in the Data list not sure if they matter but I had -
1st. 2-3OD - 53
1st. N-1UD - 95
Alternate 2C - 45
Alternate 4C - 52
Norm. N-1 UD - 59
Thanks for any info. Guys!!
Wes
 
See less See more
#3 ·
Your 2C and 4C CVIs are slightly below the normal range, but that may be due to the trans tune you are running. Not enough to worry about.

Your OD CVI is just above the normal range, which could indicate some clutch wear. Again, nothing drastic, but I would try to go easy on your OD clutch. Tap it down to "4" before you stomp on it at speed.
 
#4 ·
Is there a chart readily available that shows the CVI range? Also how do you interpret the #'? Does a lower # mean less clutch wear or is it the opposite? Thanks for the advice Transengineer.

Sent from AutoGuide.com Free App
 
  • Like
Reactions: Mopar71
#5 ·
I was going to post something like this today and stumbled on this thread, I am in the same boat, dont know what my CVI ranges are, but am thinking about droping in a revmax VB at my next service in hopes to keep my tranny healthier a little longer. I would love more insight on this also !
 
#6 ·
If you know somebody that has access to a scanner such as a snap on, you can view the transmission data and get those values.
 
#8 ·
CVIs (Clutch Volume Index values) are a measure of how much fluid it takes to apply each clutch. So a higher number = more fluid = more piston travel. Therefore, the CVI value will increase as the clutch wears. CVIs can also be affected by things like leakage within the clutch apply passage, debris in the solenoid (causing a leak of pressure either into or out of the clutch passage), etc.

Here are what I would call "typical" CVI ranges for 68RFE. Values outside these ranges do not necessarily indicate a problem. This is simply a compilation of the range of actual CVI values from 40 different trucks (with oddball values indicating a possible problem thrown out):

UD = 42-69
1st N-D UD = 84-115
Normal N-D UD = 45-70
OD = 29-48
1st 3-4 OD = 36-55
2C = 38-55
Alt 2C = 46-73
4C = 40-58
LR = 64-101

I do not have "typical" values for the Alt 4C CVI, since at the time these were compiled, the service scan tool did not display that value.
 
#9 ·
Thanks for the reply TransEngineer, I found a whole PDF from ATSG that was very detailed, even has detailed disassembly and assembly instructions, here's the values they had listed, I found it odd that the OD CVI value is almost twice as much as what you posted, did different years of the 68 RFE have different CVI values?
 

Attachments

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top