Tech: Converting a forward shift t-case to a top shift t-case
http://www.4x4wire.com/toyota/tech/topshifter/ Short Cuts

| Toyota Tech | Toyota Section | 4x4Wire.com |

By: C. Andrew Zook. April, 2002

When adding dual transfer cases to your Toyota, the rear case must be of a top shifting style - that is, one where the shifter is mounted on the transfer case itself as opposed to the transmission tailhousing. These cases are becoming harder to find - especially in good condition. One option is to convert a transfer case with the shifter in the transmission to one with a self-contained shifter.

The parts needed to do this conversion can be taken from another t-case with the shifter in the top, or they can be purchased from Marlin Crawler. Either way, the parts list is the same.


Because you have to disassemble the case, doing this swap is a good time to replace the rear output seal on the transfer case.

Overhead comparison of the 2 types of t-cases


Parts list:

Tools needed:

1. Remove rear driveshaft flange nut with 1-3/16" (or 30mm) socket and impact wrench. Flange should slide off easily after the nut is removed.

2. Remove rear section of case - there are only 2 bolt sizes which are very different in length - don't worry about mixing them. The case should come apart easily - but may need to be tapped lightly with a rubber mallet.

Splitting the rear case sections
Only 2 different bolt lengths


3. Remove the detent bolts on either side of case with a hex wrench - remove springs and balls by tilting the case to the side so that they fall out.

Remove detent ball assembly


4. Remove 4wd indicator switch

5. Looking at case from rear, slide the left shift rail forward as far as it will go, then slide right shift rail back as far as it will go.

6. Using 3/16" punch, drive out the pin on rear shift yoke (on right shift rail), remove yoke, and slide the shift rail out the front of the case.

Remove pin and rear shift yoke


7. Remove shifter interlock pin by laying case on the side to allow pin to fall out of right detent assembly hole

Remove shifter interlock pin


8. Split case apart at next section forward by removing 4 bolts - 2 on front side of case, and 2 on rear. The case should come apart easily - but may need to be tapped lightly with a rubber mallet.

Split front case sections


9. Remove top cover plate - attached with 4 bolts

10. Drive the pin out of forward shift yoke - slide left shift rail out the front of the case

11. Clean all parts before reassembly

12. Lightly grease and install new right shift rail. The side of the shifter rail with 3 "V" notches should point toward the outside of the case, and the side with 1 large "V" notch should point toward the center of the case. Slide the new front shift yoke over shift rail with the square notch facing the center of the case. Drive the retaining pin into the hole.

Comparison of front shift yokes


13. Assemble the front two sections of the case - use OEM gasket or RTV to seal the parts together - torque bolts to 29 lb-ft

14. Move the left shift rail front as far as it will go, and install the shifter interlock pin through right detent hole.

15. Lightly grease and install new left shift rail - taking care to install the new 2wd/4wd shift hub before the rail passes into the rear part of the case. Verify that the square shifter notch on the shift hub sits at the same height as the notch on the front shifter yoke - if not, the hub is backwards and needs to be flipped end-for-end. As before, the side of the shifter rail with the 3 "V" notches should point toward the outside of the case, and the side with 1 "V" notch should point toward the center of the case.

Note alignment of yoke and shift hub


16. Push the left shift rail back as far as it will go and install the rear shift yoke. Drive the retaining pin into the hole.

17. Align the 2wd/4wd shift hub through the hole where the cover plate was removed. Drive the retaining pin into the hole.

18. If installing new rear output seal, do so now.

19. Assemble the rear part of case - use the OEM gasket or RTV to seal parts together - torque bolts to 29 lb-ft

20. Apply a light coating of grease to the surface of the driveshaft flange that rides on the rubber seal in the case. Reinstall the driveshaft flange - Drive the nut on with an impact wrench, or torque nut to 90 lb-ft - peen the lip on the nut into the slot to keep it from backing out

21. Reinstall the detent assembly on both sides in this order: Ball - Spring - Bolt. Torque the bolts to 9 lb-ft

22. Reinstall the 4wd indicator switch

23. Install the oil slinger plate and the shifter base plate onto the top of the case with the 4 bolts.

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