IRS CV Joint Pop-out fix question

[E-Ticket Ride]

I have a question regarding the apparent difference between the IRS spacers we received vs. the longer half shafts we can order to fix the IRS CV joint pop-out issue.
It appears that the longer half shafts we can order from FFR are about 9/16" longer than the ones we received with our kit (FFR 7652 Mk IV Base Kit w/IRS). This is based on several posted measurements from folks who received the longer half-shafts
The spacer we received as the fix from FFR is 1/4" thick, based on my measurement today.

My question is: Why the difference?

Is the spacer shorter due to the 1/4" being the upper limit on what a spacer can be when located between the rear spindle and outer end of the axle and still provide sufficient thread outside the hub with the shaft installed?
Is the 9/16" length what it really takes to insure that the tri-lobes maintain proper seating? (I will be running wide rear tires - 315/35R17, and was planning on using Richard Oben's set up and alignment and measurements - 59.5" track width).

Trying to decide on new half shafts or using the spacers.

TIA

Chris Lewis

[bansheekev]

Try again

[bansheekev]

Replacement IRS axle assemblies (completely assembled from FFR) are $125 retail each. Not sure what the subsidized price would be but seems like cheap insurance. I ditched the spacers for peace mind. I don't want a nagging feeling every time I jump on the gas of whether one is coming apart.

I am aligning my per Richard's specs too. I just replaced the axle assemblies with the new version and called it a day.

Not happy about the extra expense but time to move on...

Kevin

[E-Ticket Ride]

I have been exchanging e-mails with FFR, and will order new axle assemblies for both sides tomorrow.

Thanks for the comments
CL

[mcwho]

there seems to be 2 issues with half shaft supplied with the complete mkiv kit.

1. Half shafts too short by approx 9/16
2 splines on the end that goes into the diff are not machined long enough and the spline shoulder bottoms out before the shaft seats properly and therefore the circlip does not engage.

apparently the splined area needs to be lengthened on some shafts where the splines are only 1 1/2 " long. Several users have used a dremel tool etc to lengthen the splines to 1.6 or 1.162 inches so that the shafts would not botton out on the splined area shoulder and the c clip would engage.