This article was put together to explain the procedure for setting endfloat in a C4 transmssion. I have found that some people get a little mixed up on exactly how it is done and it be especially tricky for new players. During teardown on a C4 rebuild, you need to take an endfloat reading. If excess endfloat is found at that time, it can be rectified in one "go-on" assembly by adding shims. This is done by simply calculating the shims required.
The easiest way to explain the procedure is, suppose you come up with an endfloat measurement of .030” during teardown and your final desired endfloat is .010”. When reassembling you will need to add .020” of shim to the "number 2" thrust, the small washer on the end of stator support. The additional .020” can be achieved by adding a thicker thrust washer or by adding a shim under the existing one. Special shims are available to go under the thrust in both .020” and .030” sizes.
Note: The "number 1" thrust washer on the back of the pump has no effect on the final endfloat figure.
See the following pictures for instruction or see the embedded youtube video found at the end of this article.
These are the shims and washers. If you are assembling only and don’t have a reading from teardown it is best to do a mock up. All internals are fitted into the case. The high/reverse drum can be left out, as it doesn’t affect the reading at this stage. Fit the pump in using an old gasket, snug the pump bolts up firm and take a reading to establish what you’ll need.
Once you have established the "number 2" washer you need to set it aside. Now is the time to work out the "number 1" plastic thrust washer on the pump. You need the pump and forward and high/reverse drums. It is easiest at this point if the drums are empty, no clutches fitted.
Start with the pump on the bench with the stator support standing upwards. The "number 2" washer you previously selected is on top. The "number 1" washer is fitted.
Slip the high/reverse drum and forward drum over the pump/stator support.
Now you need to take the whole assembly and flip it over so forward drum is down and pump is upwards.
If you look between the high/reverse drum and the back face of the pump you will see a gap between the pump and drum. You need to now source a #1 plastic thrust washer to fill the gap so it is a snug fit. If you have a few washers to choose from you can slip each one in to see what fits best.
Alternatively you could use feeler gauges to see what you require and purchase accordingly. Once you have worked out the washer you need in the "number 1" position it can be fitted into the assembly and tried for fit, again with the pump facing up. With firm pressure on the pump you can ensure the high/reverse drum is free to spin and snug so it won’t wobble around.
Note: If it is slightly firm but still spins, it is OK as once it is all assembled the endfloat will allow a little clearance. As it stands on the bench in this way it is the same as zero endfloat. Common sense is to be used here. The end result must be so the high/reverse drum is a nice fit so it doesn’t wobble around once installed.
If you are at all concerned you could do a dummy assembly again into the case with all internals in position and selected thrust washers in place and with a pump gasket installed, check your endfloat is where you want and the high/reverse drum is free without excess side movement.
Now stick the washers on the pump with transmission assembly lube or petroleum jelly to hold them in place for final assembly.
I can find the selective thrust washers from many vendors, but can't locate the shims mentioned. I really need to source those shims and would like to know a supplier. Would you help me with this information?