BritishV8 Forum

Hello everyone,

I have decided on an IRS - a Jag or other IRS for my TR7 V8 project.  I read the posts and comments here and I'm confused about what seems to be an off-centre diff. input pinion.  I know that the engine, trans and shaft in my TR7 will be true down the centre.  Logic tells me that the pinion needs to also be in line or simply won't work...  I read comments about shifting the pinion to center and cutting the control arms and halfshafts.  To me this then sets up handling issues and the same issue found in FWD cars ie: torque steer.

I know I want to avoid all of these issues and what looks like a huge amount of work.  

Can another pumpkin be substituted.  I've seen a Jag style unit with a Ford 9".  Can the Jag be modified reasonably easily, or sholud I be looking at another unit entirely?

Can anyone clear this up for me or point me in another IRS direction?

Thanks,

Trip

Trip,

All differentials have an offset pinion. You can either center the pinion in the car and have different sized axles, or keep the axles the same and offset the pinion. If there is room for the driveshaft in the tunnel with an offset, I would prefer to keep the axles the same and put the pinion off center. As long as the centerline of the pinion is parallel to the centerline of the engine, it doesn't make any difference whether the pinion centerline is above, below, to the right, or to the left of the engine centerline.

Interesting...  After all this time, I always thought that it had to be aligned.  What you say does makes sense.  In a solid axle, there is always vertical movement and maybe some lateral too(?).  

Even though this is the way it is, I just have to ask the question: Why then doesn't an off-center alignment setup cause A) torsion issues, B) huge amounts of premature wear, C) excessive strain on the bolts/mounts?

Do you know how many degrees in any direction is safe?

Thank you for the explanation, Dan.

Trip

Here is some information on pinion angles!

Calvin, thank you very much for the diagram...

I'm guessing that this also applies to a horizontal off-set. So a total of no more than 7 deg in any direction?

Do these angles also apply to coil and shock or coil-overs"?

Trip