I'm wanting to change my automatic 1970 Mach 1 over to four speed. My car is stripped down to a shell for a complete resto job. Anybody done this and how hard is it to do? Any help would be appreciated.
There are many many posts on this topic, particularly on the old forumn. Forgive me for being nosy, but shy ocnvert to a 4 speed? Why not a 5 speed? You can get the hurst shaft that will bolt right onto the T5 shifter, plus the white ball. It will look exactly like a 4 speed, but give you an overdrive gear for better gas mileage. If you covnert to a 4 speed, you use the same cross member as a C4 auto trans, but with a T5, you change the crossmember, but use the C4 trans mount. On the 70 smallblock, the easiest way to do the T5 conversion is to purchase a bellhousing from an 85-93 5.0 and use that, plus switch the linkage over from the stock Z-bar to the late model cable linkage. With this, you do not have to purchase a spacer plate for the bellhousing to trans joint. You will have to swap our flywheel, but you would have to do that anyway going to a 4 speed. You use the4 auto trans starter with the T5, whereas you have to change the starter if you go to a 4 speed. The only deal with the cable linkage is the connection to the clutch cable and also heat proofing the cable if you have headers. I ahve the C&B engineering cable linkage and I would NEVER use it again. Nothing but problems. First, the place where it goes through the firewall is not reinforced, there are no large flat wasshers even. It puts all the stress on the firewall. I ripped a hole and pulled the linkage adjustment right through the firewall and lost the use of the linkage. Ron Morris' kit actually has a mounting plate that mounts on the firewall behind your master cylinder and has its own bracket for the cable linkage. Far strong. Also, D&B welds a mounting attachment opint to the top of the clutch cable and it is a Bit** to get up there with a wrench and change the cable. The ron Morris kit does not require a welded bracket (which D&B charges $350 for!), rather it bolts onto the clutch pedal. Simple, cheap, and effective. Windsor fox makes the crossmember member for the T5.
I have a centerforce clutch/pressure plate setup, the dual friction, and I am convinced that my clutch is slipping. No amount of adjustment corrects the problem. I think it is in the linkage, or perhaps I glazed the clutch by not breaking it in properly. IN any event, I recommend either the Ron Morris setup or a hydrolic clutch linkage. The stock Zbar setup transmits vibration from the engine to the frame, requires more pedal effort. If you switch to a T5, you also have to have a driveshaft that is about 1/2-1 inch shorter. I notice that a carbon fiber driveshaft is now being made for mustangs. stronger than aluminum, but lighter.
just myu 2 cents worth after doing a conversion on my 70.
I have to agree, if you're going to go through the hassle of going from an auto to a manual, go for overdrive.
Its been my favorite upgrade to my car for almost 10 years now /forums/images/icons/smile.gif