I rebuilt my transmission and have had a few major problems. I need help. First, the new 5000 rpm stall converter was sticking out too far and binding up the engine. I finally fixed that, it was the pump gear on backwards. My other problem is I have no 1st gear. I have reverse, 2nd and 3rd. I took the trans apart again yesterday and thought the problem was a broken forward clutch sealing ring. I replace those and put the tranny back in but still no 1st. Then I replaced the Performance Automatic manual valve body with old valve body that I know works and then had no 1, 2 or 3 gear. I'm going to take the whole tranny out again tomorrow. Any experts know what could be the problem? Some tranny expert told me that there is a metal ball that comes out on disassembly that can get lost. I never saw a ball and can't find out any information on this ball in the book I have. Anyone know what he may be referring to? This thing is driving me crazy because the engine sounds extremely wicked and I want to get this thing burning rubber.
Erick, man I admire your perseverance! I wish I could help you nail down the prob but I'm clueless. Hopefully, one of these great Teckies on here can help you out. Best o' luck.
I was 99% sure that I found the problem: I had the wrong size forward clutch sealing rings in my new stator...they made different sizes for different years and I told the parts guy that I had a 72, but my stater was a later year. Anyways, I was all excited that I figured it out, so I put the tranny together and put it back in the car. On the jackstands it was working better than ever, solid in all gears. I'm still confident I fixed it, but when I went to drive it, NOT. Still barely moves in 1st gear. Second and third were solid... Looks like tranny removal #9 coming up. I'm still stumped, but I'll figure it out someday.
Have you ever worked on Auto Trans before? I am getting ready to rebuild mine, hearing that it is a fairly easy (but messy) job, that can be done in the garage. BUT, I don't really want to remove and install 3 or more times. I would rather let someone else do the work if there is a decent potential for this much hassle. Should I take it in and let someone else do the work?
It should be fairly easy, but mine has not been. It was my first time rebuilding and I did it myself so I could learn how to do it. In the end when I do get it working I'll have alot of useful knowledge. Also, I wanted to learn how to rebuild it because I'm building a race car and I figure it will blow up again and I will have to rebuild it more than once. It's messy and you have to be fairly meticulous, but it's not too bad. I can now take it all apart, mix up the pieces and put it all back together in no time. All the pieces only fit together one way.
First thing you're going to have to do is go down to your local parts house and beg, borrow, or steal a pressure gauge. The gauges also work with oil pressure, air pressure, boost (don't ask), and they have a ton of uses around the shop. Right behind the bellhousing on the driver's side of the trans is a 1/8 NPT plug. Pull it out and screw the pressure gauge into the hole and tighten it. Start the motor and run the gauge up into the car where you can see it, run the trans in all the gears and watch the gauge. It shouldn't fluctuate much. Keep in mind that if your valve body is a stock-type (even most aftermarket VB's have this feature), that reverse will have a much higher pressure, around 250-275 IIRC. If you find that your pressure is lower in low range than in any of the other 2 ranges, then you have a clutch or servo problem most likely..but don't rule out a VB problem. VB problems usually act really weird....like locking in 2 gears at once, no shift at all (stays in the same gear), etc. Now, look at how a C4 works. In low, you have the low/reverse band (rear band) applied and the forward clutch applied, and the one-way holding. If you find your pressure is low in low gear only, take a look at the rear servo and it's seals first....that servo piston has a bonded seal on it's outside surface and sometimes they can leak--but a quick visual inspection doesn't reveal anything wrong. BTW, you can test all of the clutches & servos with a rubber-tipped air blow gun but applying air to the proper holes in the trans case. I usually test it before bolting the VB down, just to make sure. If you can't find anything wrong with the servo, you already know to check the forward clutch, which can also be checked with air. But, if 2nd and high ranges work fine (no slippage) than your problem is most likely either in the one-way (sprag) or possibly a hydraulic problem.....which can be fun to find! Yep...lots of little things that can be a nightmare to find! at least when you do get it figured out, you'll know a C4 like the back of your hand!
Thanks for the help. I tried to buy a gauge yesterday but I couldn't find one anywhere. My guess is that the one-way clutch was installed wrong. If the pressures are OK and the low-reverse band works OK in reverse, then it has to be the sprag right?
The low gear in a C-4 is controlled by the low/reverse band and the forward clutch. If you have reverse and any forward gear then you should have low. The sprauge clutch (one way clutch) is for second not first. I would suggest that you spend some time looking at the hydraulic schematics and study the flow. PaulS
If the rear band is applied and holding in manual low, the sprag is doing nothing. When you are in drive and in low the rear band is not applied and the sprag would be holding the drum. If the sprag wasn't holding you probably wouldn't have low gear in drive. It is possible you have a sprag and a rear servo/band problem. In reverse if pressure is boosted it may make rear servo apply, but in low, pressure may not be enough to apply and if sprag isn't holding, no first gear.
I thought the C4 only applied the low reverse band when in manual low or reverse? Drive-first gear only uses the forward clutch and the one-way clutch?
Yea, my cousin had her one-way clutch pretty much explode on her, (many of the little accordion looking springs were broken, ) so first wouldn't really apply all the way.... you'd really have to get on it to force a shift to 2nd,
Tranny Works/Lessons Learned Finally got the thing working after 10 installs. Turns out the one-way clutch (springs and rollers or sprag) was installed wrong. It was a good learning experience and now the car can do a serious burnout.:bananaman Lessons learned: -install pump gear right or torque converter won't fit right and can ruin the engine and trans. -different years have different size metal sealing rings on the pump stator. -one-way clutch installation is tricky but is very important for the trans to work properly. I hope to be able to race it soon. Thanks for all the help guys. FYI- I found out that most reverse manual valve bodies apply the forward clutch and one-way clutch in 1st gear low without the rev/low band. When it shifts to 2nd it applies the intermediate band. Apparently, it will shift into 2nd quicker because the rev/low band does not have to release.
