thedude

Does this refer to a full tube chassis race car? The reason I am asking is to address backhalf type race cars and to clear some unanswered questions on this topic. Backhalf race cars usually retain the original OE frame from the B pillar (back of the door frame) forward to the front of the car and will usually retain factory transmission mounting (crossmember), in conjunction with a front motorplate. These designs put the engine/ trans assembly either back to factory mounting position/angle or most will be set at 0 degrees or level. Also these types of applications usually have a higher vehicle ride heights unlike their lower slung tube chassis style race car counterparts. The higher vehicle ride height in and of itself will be the deciding factor as to whether or not the CG and engine angle will have any room for adjustment. Measuring your engine crankshaft centerline height (crankshaft centerline from race track surface), will be the first dimension you will need to determine. Remember that between 9" - 12" from the race track surface is ideal, next measure your rear end drive pinion center height, then the distance between the transmission output and the rear end drive pinion. These three recorded measurements will immediately indicate how much angular driveshaft misalignment is in question. To be perfectly clear, you would never want to try to fix an angular driveshaft misalignment problem that was overly extreme. You would never exceed more than 3 degrees of engine/transmission angle, (transmission output angled upward).

Also to clear up some other questions in stock type or backhalf race cars where the rear end drive pinion center is lower than the transmission output center, there really is no remedy to fix operating the driveshaft in an angular position. Again, the vehicle ride height plays a major role in the rear end drive pinion height. The last post mainly refers to lower ride height tube chassis race cars where there is between 3" - 5" of ground clearance and the rear end drive pinion center is higher than the transmission output center.