FFR Rear Disc Conversion Axle Choices

[Doc76]

Can anyone that has used this FFR rear disc conversion kit on the 1987-1993 Ford 8.8 rear end provide advice on the choice of axles?
I’m am stepping up to 31 spline and sticking with c-clips
I haven’t found the “easy button” on this one.
I looked into Motive which are widely available here but local guys here said don’t touch them, they’re cheap for a reason.
Moser/Strange are extremely expensive to ship to my location but for quality I’m willing to pay for it.
On the Moser & Strange it seems the flange OD is too large for the FFR disc inner hub. Maybe it’s something to do with the fact it’s an ‘94 disc? Along with this it seems that the center hub bore for the “OE” fitment is 64mm as should be expected. The discs from the kit has a bore of 70mm. So I have the LMR spacer rings but was looking to possibly eliminate the need for them.
Do I order the OE fitment style axles in a 31 spline and OE length (my test fit of the kit worked very well on the old 28 spline axles so length is good) and turn down the flange on my lathe and use the LMR spacers?
Is that really the only option?
Any advice on this would be appreciated

[michael everson]

Maybe give Mike Forte a call. He might be the "easy button" on this one.
Mike

[gbranham]

Mike Forte or Richard Oben of North Racecars are definitely your easy buttons.

[StangRacer]

Doc, if you don't go through Mike or Richard just call Moser directly. They are very helpful and know all of the dimensions you need. I just ordered custom c-clip 31-spline axles from them last Monday and they arrived yesterday. I had to order shorter axles due to having a narrowed housing for pin-drive wheels. I gave them the dimensions of the housing, advised I needed flanges to fit 94-04 rear disc brakes, and the Foxbody brake offset which is 2.5".

[Doc76]

Thanks guys
Looks like the Moser A883151 (https://mosercanada.com/8-8-ford-31-...ang-5-lug.html) OE fitment axles are the ticket however I will still need to use the LMR hub centric spacers I already have as these are 64mm hub bore. Axles are on the shelf in Canada with free shipping and returnable should there be an unforeseen fitment issue.
Alternatively A883151sn is the correct 70mm bore for the rotors supplied in the FFR rear disc conv kit however not available up here at this time.

Is there any other reason to wait on the 70mm hub bore axles other than to not have to use spacers?

[StangRacer]

Thanks guys
Looks like the Moser A883151 (https://mosercanada.com/8-8-ford-31-...ang-5-lug.html) OE fitment axles are the ticket however I will still need to use the LMR hub centric spacers I already have as these are 64mm hub bore. Axles are on the shelf in Canada with free shipping and returnable should there be an unforeseen fitment issue.
Alternatively A883151sn is the correct 70mm bore for the rotors supplied in the FFR rear disc conv kit however not available up here at this time.

Is there any other reason to wait on the 70mm hub bore axles other than to not have to use spacers?

If you are using the Ford traction lock carrier the spider gear pin is .875 on the 31 spline carrier compared to .750 on the 28 spline carrier. To maintain the same width the 31 spline axles should be 1/16" shorter to compensate for the thicker spider gear pin.

[Doc76]

If you are using the Ford traction lock carrier the spider gear pin is .875 on the 31 spline carrier compared to .750 on the 28 spline carrier. To maintain the same width the 31 spline axles should be 1/16" shorter to compensate for the thicker spider gear pin.

Very good to know thank you. I am using a 31 spline Trac Loc. I didn't come into that info anywhere!
That added width is actually a benefit to me. The lower corners of the coil over mounts when I was drum were ~3/16" away from my rim. With the test fit of the FFR kit on the OE 28 spline axles, the discs gave me another 1/8" in width which was great. If that pin is 1/8" wider that's even better.
I plan to call Moser Monday for actual dims on the A883151sn to make sure they are identical to the ones I have now with the exception of the spline count. I'd like to not have to use my LMR hub-centric spacers if possible.
At this point with the variability and lack of info on parts I am not trusting anything and want to test fit my brake kit again with the brand new axles before I pull my rear end for the rebuild,

[CraigS]

I agree w/ getting rid of the spacers. At one point I used them. Biggest problem is they would stick in the wheel. Spacer comes off w/ the wheel, rotor falls off center. Not a huge deal but an aggravation for sure.

[rich grsc]

If you are using the Ford traction lock carrier the spider gear pin is .875 on the 31 spline carrier compared to .750 on the 28 spline carrier. To maintain the same width the 31 spline axles should be 1/16" shorter to compensate for the thicker spider gear pin.

I do not think that is correct, I believe the 31 spline spider gears are machined for the correct fit

[StangRacer]

[/B]

I do not think that is correct, I believe the 31 spline spider gears are machined for the correct fit

Rich, that was information I gathered from Moser when I ordered my axles... fingers crossed I didn't get bad information.

[Doc76]

Rich, that was information I gathered from Moser when I ordered my axles... fingers crossed I didn't get bad information.

StangRacer rest easy.
I just went and checked the 28 spline Ford traclok carrier in my diff and can confirm the spider gear pin is .750 and on the brand new Ford Performance 31 spline carrier I have on the bench waiting to go in the center pin is .875”.

Doesn’t hurt my situation but nice catch!