BlackMess Posted February 16, 2010 Report Share Posted February 16, 2010 I changed the motor mounts in my car and therefore raised the engine approx 1.5". What would the ideal pinion angle be? 0*, -2*??? Car is a 1993 RX-7 with a ls1 / 4l60e. Also I measure when suspension is under full load correct? Thanks! Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted February 16, 2010 Report Share Posted February 16, 2010 (edited) pinion angle on a irs car......depending on all the stock rubber mounts in the rear end, -2 to -4* but heres some basics on it http://www.fulltiltboogieracing.com/pinionangle.htm you want it set to about the same angle the crank is... Edited February 16, 2010 by Removed Quote Link to comment Share on other sites More sharing options...
Tinman Posted February 16, 2010 Report Share Posted February 16, 2010 It can be difficult to get correct or even acceptable pinion angle on an engine swapped RX7 due to the output shaft of the transmission being much lower than originally. This is because the rotary's engine eccentric shaft is in a higher location than the crankshaft of a piston engine, therefore the transmission output is equally out of place. Most shops ignore this step in the process and many get away without any problems. But you're leaving horsepower on the table and setting yourself up for accelerated drivetrain wear if the problem is not addressed. I have found a solution for FCs and have tens of thousands of miles and multiple track days with zero issues. But I don't have any experience with FDs. I would suggest finding a competent fabricator to take a look at your car and find a proper solution. Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted February 16, 2010 Report Share Posted February 16, 2010 It can be difficult to get correct or even acceptable pinion angle on an engine swapped RX7 due to the output shaft of the transmission being much lower than originally. This is because the rotary's engine eccentric shaft is in a higher location than the crankshaft of a piston engine, therefore the transmission output is equally out of place. Most shops ignore this step in the process and many get away without any problems. But you're leaving horsepower on the table and setting yourself up for accelerated drivetrain wear if the problem is not addressed. I have found a solution for FCs and have tens of thousands of miles and multiple track days with zero issues. But I don't have any experience with FDs. I would suggest finding a competent fabricator to take a look at your car and find a proper solution. what do you do with the fc's? i know on the fd's, alot of guys run a ford irs center section, and custom axles..but i havent seen anyone address pinion angle on them...which is i think some of the issue is with eriks car blowing diffs(he always seems to break the spider gears into little pieces.) but i think thats just more along the lines of to much torque for it to handle MMS makes a kit to take care of the ford issues on pinion angle on the lowered cars. Quote Link to comment Share on other sites More sharing options...
Tinman Posted February 16, 2010 Report Share Posted February 16, 2010 what do you do with the fc's? i know on the fd's, alot of guys run a ford irs center section, and custom axles..but i havent seen anyone address pinion angle on them...which is i think some of the issue is with eriks car blowing diffs(he always seems to break the spider gears into little pieces.) but i think thats just more along the lines of to much torque for it to handle MMS makes a kit to take care of the ford issues on pinion angle on the lowered cars. On the FCs it's a two part process, both pretty simple. First, I mill the tops of a pair of Delrin differential bushings at an angle and to a certain height. Can't remember off hand what angle or height I used but the math is easy and will vary depending on the transmission output shaft height and angle. Care has to be taken to get them properly indexed in the housing and a spacer is needed to take up the distance below the housing or the nuts will not tighten completely. This raises the rear of the differential housing. The second part requires some welding and there are two ways to get the same result depending on the cars purpose. A solid front differential mount can be fabricated in a manner to lower the pinion end of the differential to the point the center section nearly touches the subframe. Or if the factory rubber mount is preferred, the subframe can be modified to alter the mounts attaching point. In either case the subframe should be reinforced at the mount location. Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted February 16, 2010 Report Share Posted February 16, 2010 ..ok, same stuff with the cobra cars then. they make a mount kit for the center section with the proper angles and what not. they go to a thicker rear cover, with a more solid mount setup. let me see if a can dig up my fd pics with the rear sub frame stock and with the cobra centers in them Quote Link to comment Share on other sites More sharing options...
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