1971 Body/Chassis FSM

1971-74 F Engine FSM

Page Index


Page 6 of 7

Rebuilding the 3 sp T-case: Reassembly Page 3

MudRak Dual Seal Mod

This mod is for those whose T-Case output shaft has a bad groove worn in it, and a new seal does NOT stop the oil leak. This mod adds a second seal that will ride in a new location on the shaft eliminating the leak.

Since my Emergency Brake Drum has a slight groove in it I decided to try this mod. It was much easier than I thought it would be, just a bit time consuming.

Fig. 1

Coated Speedo Housing

Fig. 2

Lip to be Removed

Fig. 3

Lip Removed

Fig. 4

Seals Installed Front

Fig. 5

Rear View

Fig. 6

Greased Lips


  1. Fig. 1 shows my nice cleaned and powder coated speedo housing ready to be hacked on!
  2. The stock seal sits flush with the machined surface of the speedo housing. The seal is kept straight in the bore by a lip as seen in Fig. 2. It is this lip we will be removing. So how will we keep two seals straight in the bore? Careful insertion.
  3. I used a Dremel tool with a 1/4" carbide bit to slowly remove the lip. Don't expect this to remove material easily! This is a cast IRON housing, NOT aluminum. Take your time, you don't want to remove too much material.
  4. Fig. 3 shows the finished job. I finished it by putting a fine grit sanding drum on the Dremel to smooth it up.
  5. Get your two seals (AD2651E), coat the seal outer shells and speedo housing seal seat with oil. I used a plastic faced hammer and carefully started the first seal in keeping it square in the bore. I drove it flush with the machined surface.
  6. I placed the second seal directly on top of the first seal and start driving it in. It takes harder whacks since you are actually driving two seal at once. Continue to monitor the seals so they don't get cocked in the bore! Drive the second seal until it's also flush with the machined surface. That's it! See Fig. 4 for a front view and Fig. 5 for a rear view of both seals installed.
  7. Fill the seal lips with grease to provide lube for the front seal which should not receive much lubricating oil. See Fig. 6.

Fig. 7

Driven Gear and shaft sleeve

Fig. 8

Inside O-Ring

Fig. 9

Driven Gear Size Stamp

Fig. 10

Drive Gear Size Stamp

Fig. 11

Speedo Cable End Parts

  1. See Fig. 7. Get the speedometer driven gear, and speedometer shaft sleeve. Again wash the parts in hot soapy water, rinse and blow dry. Install a new rubber O-ring on the shaft sleeve.
  2. Using a dental pick remove the small o-ring from the machined groove INSIDE of the shaft sleeve. Install the new o-ring. See Fig. 8.
  3. If your tires are larger than stock and just happen to be 33" this is an excellent time to recalibrate your speedo. Order the following from C-Dan : 33403-60030 (16 tooth) driven gear and match it with a 33481-60030 6x17 drive gear (which is what came in my transfer case). See Fig. 9-10 to see where the size is stamped.
  4. Do NOT install the speedo gear back in the housing until AFTER you set the pre-load on the output gear! It's possible to strip the gear if you turn the shaft backwards while setting the pre-load.


Fig. 12


Fig. 13

Housing Installed

Fig. 14

Torquing E-Brake Drum

Fig. 15

Testing Pre-Load


  1. Locate the shim, Speedo drive gear and spacer and install on the shaft as shown in Fig. 12.
  2. Get the gasket for the speedo housing and trim it to fit if necassary. Coat the gasket on both side with blue RTV, place it over the housing, put the shim in place then place the housing over the output shaft. Install the 5 8mm x 1.25 bolts. Tighten to 7 to 11 ft lbs. See Fig. 13. It's important to get these bolts to their proper torque! They are what help set the pre-load on the bearing NOT the e-brake drum nut torque!
  3. Temporarily install the parking brake drum and tighten the retaining nut to 101-123 ft lbs. You will need to use a big wrench jammed in the drum studs to hold the shaft while you tighten it. See Fig. 14. Place the transfer case into neutral and disengage the front drive.
  4. Refer to Fig. 15 and attach a spring scale to a drum stud bolt set at about 11:00. Pull on the scale with an even force. It should take 10-13 ft lbs to start the drum moving. Repeat a couple of times to verify the reading.
  5. If your reading is lower than 10-13 ft lbs you will need a THICKER shim. If it is higher than 10-13 ft lbs you will need a THINNER shim. You will need to pull your shim and measure it to see which way you need to go. My shim was measured at .008. Any Toyota dealer can get the shims. The shims are available in the following thicknesses.


    Part No.




    0.10 mm (0.0039")
    0.015 mm (0.0059")
    0.20 mm (0.0079")
    0.25 mm (0.0098")
    1. My measurement was 5 ft lbs so I needed to order a thicker shim. I just ordered the three I did not have from the set so I could mix and match. I ended up with .008 and a .0039 shims to get the proper pre-load.
    2. Insert the driven gear into the sleeve after lubing it with some 90W. Install the shaft sleeve back in the speedo housing and install the retaining bolt and washer.


    Final notes: The transfer gears, spacers and PTO gear if used will be installed when you mount the T-Case back to the tranny. See Page 35.

Next up: Reassembly: Page 4.




1971 Body/Chassis FSM

1971-74 F Engine FSM

Page Index

Hosted by Global Software, Inc.

©1998 - 2015 Mark C. Baker Web Designer

Please: No part of this web site may be used without express permission... email mbaker@globalsoftware-inc.com for permission.