Week 33: November 11th 2001:
First off, Acknowledgements & Thanks to the following people:
Mike Challenger, For all of
the custom machining
Pat Hall, For taking a day off from work and helping me install this transmission!
Carl McIver, Listening to me complain, and helping me out with parts
It's time for an update on the project. Well, it's taken a long time to actually figure out what to do about the clutch. Let me tell you the story (the two month long story, for your amusement). Well, my first thoughts in repairing the clutch was to just replace the throwout bearing since obviously (ya..) that is what was wrong. Well. Here in lies the problem with custom engineering and putting in transmissions and clutches that were not exactly meant to be run together. The transmission snout on the supra transmission is about 3/4" to short so when the bearing is engaged, there is not enough support and the bearing wiggles slightly. This coupled with the fact that the bearing spun freely on the carrier (no locking pins) it machined a nice groove in the bearing carrier. Ha! So, this is where the bearing was sticking and so not releasing the clutch! So, I have to fix this in such a way that this won't happen again. First of all, I had a new snout for the transmission machined that was 3/4" longer than stock. I had the old scratched up snout removed from the transmission front plate and had this new snout braised in. That worked great and it fully supported the bearing. Now, how to stop it from spinning? Ha! The dang bearing is a solid unit made out of hardened steel. If I welded it (which I wanted to do) I would have cooked the bearing. Since it was hardened steel, I couldn't drill it to install a pin (I have since been told that some machine shops can do this.. oh well). Anyhow.. I thought long and hard and decided to try out a hydraulic bearing. So, I ordered one of Howe's hydraulic throwout bearings for stock clutches. What I found great was that the bearing snout diameter was exactly the same as a GM tranny. hahah. So, no machining was required there, it fit perfectly. So, next problem.. The Girling master cylinder for our TR7's do not displace enough fluid to significantly move the bearing. So, Howe in their documentation say that the bearing is designed for a 3/4" master cylinder. So, I order one of these Tilton master cylinders with a remote reservoir kit. Hook everything up and bench test. Not enough displacement. What the heck? Ahh! The documentation doesn't tell me how much of a THROW the 3/4" cylinder needs to have. Obviously the weak 4" that they TR7 pedal gives us isn't enough. I've got two data points now though, one with the 5/16" Girling and now one with the 3/4" Tilton. I figure a 1" master cylinder will be enough. I get one of these, test it and low and behold, it works. Now, before you think I have this problem solved, let's go to how the hydraulic lines will reach the bearing. First attempt was a set of bulkhead fittings on the bell housing. Holes were drilled and everything before a very astute individual caught something that I totally missed.. Pressure plate clearance. I'd been so focused on getting my bearing preload set right that I didn't even thing about the pressure plate! Damn! Back to square one. So, Here is what myself and a few other talented people have come up with. The bell housing is thick in the back and has two bosses. One on either side of the bearing carrier so The bell housing was drilled and tapped and fittings were installed. A coupler was installed on the top of the transmission where the bleed nipple will be installed as well as the hose from the master cylinder. Man, this has taken about two months to figure out.. On and off, one step forward, two steps back just about all the time. So, the following photos I hope will show you how the transmission was modified, the installation of the bearing, and how the engine compartment comes all together. Enjoy!
Tilton master cylinder pushrod all lengthened correctly for the TR7 pedal w/ clevis
Clevis pin all welded up
External view, you can see the fittings screwed into the back of the bell housing and then hoses going up to the connector block mounted up on the top of the transmission. All connectors have Teflon tape on the threads to prevent leaks
Interior of bell housing, the bearing all installed with the correct spacing. Two stainless braided hoses (made myself with aeroquip fittings) They have been routed in such a way that the hoses will never rub against eachother
Photo of car up on ramps ready to put transmission back in...
Here is a shot of the Tilton master cylinder, the reservoir is mounted over next to the wiper washer fluid bottle. There is a short aeroquip hose that goes between the master cylinder and the bell housing
If you can actually see with all these hoses in the way, the hose from the master cylinder is screwed into the connector block on the bell housing. If you are really observant, you can see one of the holes where I had drilled for the bulkhead fittings (now plugged with aluminum and epoxy)