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Hydraulic Throwout Bearing Conversion


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I have a 260Z with a late model small block 435HP Edelbrock clone motor and a Richmond Super T10 4 speed and old Z28 bellhousing. I replaced my Novak Jeep hydraulic clutch fork conversion kit with a Tilton master and hydraulic throwout bearing. I also used a Centerforce dual friction clutch. I encountered several problems and came up with solutions. You must use the 15/16 inch Master with this universal TO bearing requiring the replacement of my 3/4 Master to get the full throw. The fittings on the Tilton TO bearing stick out too far to allow stabbing the transmission in the bell housing. I am not fond of pulling engines to change clutches so I ground 1/4 inch clearance in the bell housing top and bottom. The combination lacked 1/4 inch to have sufficient freeplay for the clutch to release. This was solved by ordering a $65 aluminum mid plate intended for dirt track, scribing and jig sawing the unnecessary material. This was cheaper than having a machine shop cut out a spacer. The midplate was .263 which was more than I needed for freeplay. Also, an extended pilot bearing was necessary along with longer line up pins. I was sent aluminum pins but felt these were not strong enough. I made new pins out of the smooth section of 5 inch long grade five 5/8 inch bolts. The new pins should be tapered at each end for easier fitting. A caliper is necessary to get the correct diameter pins to match the factory block holes. These do more than help you line up the bellhousing bolts and need to be a tight fit. The last problem was the JTR transmission mount whose center transmission bolt hole had to be redrilled .263 further back. I had enough freeplay in the driveshaft so no change was necessary. The final problem was that the Earl's lines contacted the clutch is they wer allowed to be in the natural position This was solved by a bracket using the side plate of the transmission along with an insulated cable clamp that pulled the hydraulic lines against the back of the bellhousing. A spring was used to keep tension as the lines passed under the tranny and followed the speedometer.

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It's just the combo of different parts from different manufacturers. When I put in my HTOB, I went thru much the same process, although my spacer was 0.150. I was using a Ram clutch, McLeod TOB, GM bellhousing, and Tremec trans. Machining down the front bearing retainer on the trans would have been another solution.

 

John

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It's just the combo of different parts from different manufacturers. When I put in my HTOB, I went thru much the same process, although my spacer was 0.150. I was using a Ram clutch, McLeod TOB, GM bellhousing, and Tremec trans. Machining down the front bearing retainer on the trans would have been another solution.

 

John

 

I agree but it was pretty frustrating to have Centerforce, Tilton and Summit techs tell me that that combination would work. I finally got hold of a Centerforce tech that said he did not know of anyone that made this work without decreasing the usefull life of the Dual Friction clutch. He also recommended a McLeod TOB. I discovered a place named car shop inc. They were able to provide me with the knowledge and parts I needed to complete the project.

 

Machining was one of our thoughts (my friend is an old school tool and dye maker) but the new Tilton bearing retainer was made of aluminum instead of steel and only 1/2 inch thick. He also recommended to ♥♥♥♥ can the aluminum extended dowels and make them from steel.

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  • 3 months later...
I'm having simular issues w/ my tilton 3/4 master and HTOB. I have a GM T-5, camaro bellhousing and Ram Flywheel and clutch. Waiting to hear from Techs at Tilton and Ram... frustraiting...

 

Make sure your master cylinder diameter is compatible with your HTOB. I had to ♥♥♥♥ can my original and get the next size. Also, you need to take a look at the length of the clutch rod. The problem with sizing is lack of volume to properly "inflate" the slave cylinder, thus less throw. Screw the damn phone techs and ask for the engineers that designed the product. It also helps to have an interpreter like I did.

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