First Question. how much of the splines need to engage between the yoke and the tranny. I just put my SECOND new C4 in the mav and am working on eliminating possible causes of failure. I think i know what caused the death of the last tranny but this is one of my last questions. I'll take some pics when i'm working on her today, and post later tonight. second question. anybody know more info on vacuum requirements for the modulator on a C4. the lit with tranny says min of 12 inHG at idle. is this in "free idle" or "in gear idle". due to my cam i have rather low vacuum. i could run faster at idle, but don't want to. Third Question. which port on a C4 is feed and return for the tranny cooler loop. I would like to know before i plumb. due to the nature of my tranny coolers it is important which one is first in line. also would like to put the temp sender in return line. I DON'T want to throw away another Grand. any advice or info is greatly apreciated. Thanx guys AND gals.
I believe you should have about 1 1/2 inches of shaft showing. I'm not sure about the vacuum. As for the cooling lines, it doesn't matter. It's just a cooler and will cool either way.
pic of yoke this yoke and driveshaft are off the 76 4dr mav 302/c4. as ya can see it rides a bit shallow on my setup (but seemed to work ok). ya'll think this is ok to use as is, or should i get a custom(longer) driveshaft made. "to err on the side of caution"
Hmmm...I think I would be scared of that. I'm not sure how far the shaft comes out when the rear end does it's normal twisting but it probably moves in and out a good inch.
I had a similar issue years back when I swapped the 250 for the 302. My shaft did not go in as far so it may be a common thing. I never did get an answer if there was a difference between the six and eight cylinder drive shaft but I never thought there was? I am pushing my drivetrain quite a bit harder that the factory setup, I did have the shaft balanced and the u-joints replaced but its been working ok for almost 10 years and 15000 miles and you can see the old polished part where it used to go deeper.
When I swapped in the 302 and Toploader my Driveshaft also does not slide into the tailhousing as far as it did with the 6 cylinder C4 setup ...
This is probably more related to Dan's situation than yours, but here is info from Charlie's website: "My experience with the toploader AND T5 is that both require a longer manual-specific front driveshaft yoke. (The yoke is different from Toploader to T5) The reason for this is that the toploader's tailshaft has a bushing that the yoke rides in. A shorter C4 yoke will fit the splines on the toploader or T5, but is not long enough to reach the bushing inside, resulting in vibration. " Here's a link to the article: http://www.geocities.com/cping3/stickshift.html
Interesting ... Pretty sure I have verified in the Ford Service and Part manual that the C4 and Manual tranny used the same yoke ...
I dunno, I've heard both. I have always thought the yoke on my driveshaft from the grabber looked long, but have never compared the two side by side.
More research indicates Ford only made 2 different 28 spline yokes ... one for internal snap rings and one for external snap rings. Both were the same length ... I reused the original 6-cylinder drive shaft .. could the V8 shaft be an inch or 2 longer? I have 3 drive shafts sitting at home ... I'll have to check them out ... At least one is out of a V8 ... I think ....
Here is some info ... Mavericks and Mustangs with 6-cyls and 302's used Driveshaft Yoke Code 3 .... Both C4, 3-speed and 4-speed. Also ... the dimensions of the driveshafts were identical ... however, there were different part numbers for 6-cyl vs. V8 .. perhaps a different balance? The second pic shows the driveshafts .. 3 indicates yoke Code 3 ... next is the diameter and finally the length ..
Im not sure exactly how much vacuum youre supposed to have, but I can tell you this- *not enough vacuum will not cause transmission failure, it will just cause the shift points to be at higher rpms and speeds and cause the trans to shift harder. *too much vacuum will cause tranny failure by not allowing enough hydraulic pressure in the trans, causing the shift points to be at too low of speeds and rpms, and will allow the trans to shift softer which can allow clutch slippage. pull your vacuum off the intake manifold
