tc429
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- #1
need some clarification from a transmission guy/someone at ford...what exact model transfer cases are put in our trucks? a discussion came up about 4A mode- I had always assumed 4A had a open center differential in the transfer case PLUS a dog-type clutch to lock the diff in 4H modes, but where the XLT type cases(without 4A mode) had ONLY a dog type clutch only to lock in power to front driveshaft....
a ford guy said the 4A had no center diff, just the locking clutch came on as needed by wheelslip/power detection...this seemed wrong to me, so went out to see...started trucks (tried both the 19 and 22, both lariats with 4A) put in 4a to lock in the axle hubs, jacked up one front wheel off the ground and spun it...had expcted it to just turn until gear lash was gone, nope- it spun... spinning it quicker though- KLUNK. it locks in same as 4h... Let it sit a few seconds, click- it releases and can be spun again. feels to me like hes right, no center diff in 4A- but then if so the power split display is lying, as in 4A it always shows some power delivery to the front tires in 4A.
To me, this is still a head scratcher, but it sure seems to be freewheeling unless enough slip detected to klunk it in... I'd like to know what exact model xfer cases are in use and pick up the ATSG manuals for each just to really see exactly whats inside and fully understand how they function. the ATSG manuals have great diagrams, and are available cheap- many years ago was able to redo my TH700R4 in a couple evenings for a total of 85 bucks...50 soft parts, 15 used (29 element) forward sprag, 20 for the book... a buddy of mine had 3 times spent 1200-1500 to have his fixed each time, but they kept putting the same crappy 19 element or whatever 1985 sprag back in.
anyways, thoughts/comments appreciated, but still really need to know models and get a factual 'whats in the box' manual to know for sure...oldest son and I have 3 '4A' lariats, next oldest son has 4H only xlt- i just want to really be able to understand the differences without tearing one apart... have heard comments both ways from guys in the know, and someones wrong about 4A... from jacking up/spinning one wheel it sure looks like no center diff to me- so think that guy is correct, which is a bummer really- but that would mean dash display is lying in 4A about power delivery...
a ford guy said the 4A had no center diff, just the locking clutch came on as needed by wheelslip/power detection...this seemed wrong to me, so went out to see...started trucks (tried both the 19 and 22, both lariats with 4A) put in 4a to lock in the axle hubs, jacked up one front wheel off the ground and spun it...had expcted it to just turn until gear lash was gone, nope- it spun... spinning it quicker though- KLUNK. it locks in same as 4h... Let it sit a few seconds, click- it releases and can be spun again. feels to me like hes right, no center diff in 4A- but then if so the power split display is lying, as in 4A it always shows some power delivery to the front tires in 4A.
To me, this is still a head scratcher, but it sure seems to be freewheeling unless enough slip detected to klunk it in... I'd like to know what exact model xfer cases are in use and pick up the ATSG manuals for each just to really see exactly whats inside and fully understand how they function. the ATSG manuals have great diagrams, and are available cheap- many years ago was able to redo my TH700R4 in a couple evenings for a total of 85 bucks...50 soft parts, 15 used (29 element) forward sprag, 20 for the book... a buddy of mine had 3 times spent 1200-1500 to have his fixed each time, but they kept putting the same crappy 19 element or whatever 1985 sprag back in.
anyways, thoughts/comments appreciated, but still really need to know models and get a factual 'whats in the box' manual to know for sure...oldest son and I have 3 '4A' lariats, next oldest son has 4H only xlt- i just want to really be able to understand the differences without tearing one apart... have heard comments both ways from guys in the know, and someones wrong about 4A... from jacking up/spinning one wheel it sure looks like no center diff to me- so think that guy is correct, which is a bummer really- but that would mean dash display is lying in 4A about power delivery...
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