IRS CV joint popped out

[oneillpete]

My car has been on the road for a few weeks. I was doing a spirited shift to 2nd gear when I heard the pop in the rear end. On the driver's side of the IRS, it appears the 1/2 shaft is too short and the rollers extended out of the cup. The force was so extreme it pushed the pumpkin to right about 1 inch and damaged the rear bracket. The hub bearing has been damaged as well it rumbles a bit and will need to be replaced. I am using pin drive widths.

This is what I have done so far:
Both shafts measure 27" compressed, I have read on the forum somewhere that they should be 27 1/2", FF says they should be 27”

The distance between the pumpkin and the hub on the driver’s side is 5/16” more that the passenger’s side. 50% of this space can be accounted for in the heim adjustments, so I am not too concerned over chassis variables.

On both sides, the heim has been extended approximately 5/8th of an inch, a little more on the left.


I repaired the pumpkin bracket and welded on gussets to make it stronger.

I fabricated temporary 1/2' spacers between the outer CV shaft and the hub

I have been working with Rick Masters from FF to look for a solution, but to me the obvious one is that I need longer 1/2 shafts. Rick has confirmed from some photos I sent him that my control arms are pin drive width.

Rick mentioned that this has happed a few times this year with other cars, but was not aware of what the final resolution.
While I feel that FF team has acknowledged my problem, I don't feel that a solution is forth coming.

My expectation is that the correct length 1/2 shafts are sent to me, as well as a replacement for the damaged hub. There appears to be several owners with this problem

Posting this thread on the factory five site to raise visibility to the FF leadership team , while I was lucky, this failure could have caused a serious accident.


Cheers Pete
10152101531015410155

[FritoBandito]

Damn. This is happening a lot. I spent a lot of money on custom half shafts to put up with the extra HP of the motor I'm buying but I had them made to stock lengths. I wonder if Porsche CVs are more or less susceptible to this problem?

Mario

[rich grsc]

As posted on the other site, that shaft is incorrectly assembled. Did you receive it that way from FFr? The tri-lobe should be almost flush with the end of the axle. The large heavy snap ring should be in the inner axle groove, and the wire spring ring in the outer groove. One side of the tri-lobe has a recess, that faces out so that the spring ring expands into the recess.

10195

[oneillpete]

yes, the 1/2 shafts and CV joints were shipped to me from FF assembed. I agree that making this change will give me perhaps a 1/4 inch, which will help, but is still insufficent.





As posted on the other site, that shaft is incorrectly assembled. Did you receive it that way from FFr? The tri-lobe should be almost flush with the end of the axle. The large heavy snap ring should be in the inner axle groove, and the wire spring ring in the outer groove. One side of the tri-lobe has a recess, that faces out so that the spring ring expands into the recess.

10195

[oneillpete]

Received an update from FF today, I was informed that they are going to mock up a pin drive IRS in their shop and make some measurements.

[emac]

Interested in what they come up with.....

[JeepFlyer]

Is this an issue with normal width IRS as well? I was leaning toward going with an IRS, but if this is an issue that could be systemic, it's kind of a turn-off. Is the IRS setup from Mike Forte essentially the same? Any suggestions for a beefed up IRS to handle more power?

[Hankl]

This is not an issue with the standard IRS shafts. I would caution all, that we need to wait and find out what the cause really is. As Pete said, the Tri-Lobe was installed incorrectly, and what else is wrong is merely speculation. While we would all like the "Instant" answer, everyone involved, the Car owners and FFR, need to get to the bottom of the problem, and not just jump around like a bunch of Taliban at a Drone Strike!

Hank :cool:

[oneillpete]

Talked to Rick Masters today from FF, they have mocked up a pin drive and Standard IRS. He told me that indeed it appears that the 1/2 shaft and or CV is too short for proper suspention travel. They are talking about longer 1/2 shafts, or a different CV (deeper cup) or even spacers. I'll be getting an update next Tuesday.



Cheers, Pete

[MPTech]

Too short for Pin Drive only or both?

[oneillpete]

he said both

[bansheekev]

he said both

Based on my standard width IRS setup, I concur that the are indeed too short in my case (I received my kit in January 2012). I have been very patient asking a lot of questions, taking measurements over and over on my alignment and track width, and making sure that I was not missing something. I didn't want to do the cry wolf thing only to regret it. Based on all my meaurements and findings the tri-bearings on mine protrude from the tri-lob ~20% in normal suspension travel. The most logical solution appears to be longer shafts.

Kevin

[rich grsc]

The shafts are being assembled incorrectly. They are not using the correct snap rings!

[FMJ]

My complete kit with IRS is from early 2011. Should I be concerned? Its not on the road yet but will be soon.

-Fred

[emac]

Glad they are acknowledging the problem. I hope we see a solution soon. My car was delivered in Nov 2011, standard drive IRS, and is on the road, so I am very concerned. At rest, I can feel the lobe at the differential side, but it isnt hanging out.

[CraigS]

If any of you have a Lexus or Toyota front or all wheel drive sedan, check the inner joints on your axles. Some of them have a trilobe joint and I guarantee you can't feel the lobe by squeazing the boot.

[emac]

Any news from FFR?

[dyno7351]

I have an IRS setup (not pin-drive) and am wondering how much end play there should be between the differential housing and inboard hub. I have around 1/8" and that seems a bit excessive.

[oneillpete]

I talked to Rick Masters today. This is what he told me:

FF acknowledges that the driver's side ½ shaft is too short.
They will be supplying a spacer to all IRS owners (stn and pin). He said the spacer will be 1/4" (this seems too short to me) Spacers should be available in a few weeks. He also said that the spacer is only required on the driver's side, (which is also surprising to me, they base this on the fact that they have only had driver’s side failures)
They will also provide a longer 1/2 shaft for those people who are not satisfied with the spacer solution for $30.00, but it will take several months to manufacture the shafts.
Personally I made and installed 1/2" spacers on both sides.

So this is progress, even if I don't agree with the details of the solution. Perhaps Rick did not get the details correct regarding the size of the spacer, or the need for driver's side only, or both.

[vnmsss]

I've had the driver's side pop out at over 100 mph on three separate occasions (the first time in May 2010) Needless to say, it's no fun.

The first time was following the installation of a completely assembled set of new axles from F5, and I had the the driver's side pop out in my third session on track....Upon further investigation, we discovered they had been assembled with NO clips on the outer ring of the inboard joint on either axle (DS or PS)...Yikes! Somehow the PS stayed together.

We pulled both axles and repaired the PS one, however, the DS was toast from the damage of partial engagement for at least a brief time before pulling out altogether and hammering its way to a stop while I managed to find a safe place to get off track..... We'd already been on alert with our IRS system as we'd experienced the axles nuts backing off despite all attempts to secure, and had the lower control arms snap at the X on two separate occasions. With the axles now prone to poppoing out, we became intensely vigilant with the IRS system.

The next time was at the 25 Hours last year (2011), when we'd replaced the axles again in preparation for the 25, and I had the DS pop out from the diff three times in practice sessions. This time, I was completely baffled, as, not wanting to have the same "fun" I'd had in May, Coupe builder John Card and I installed the clips and axles ourselves. As we looked for a solution at the track, we found an even bigger, beefier clip and installed it, and I went back out for another run....It popped out again!

I talked to Jim Schenck (he was there at the track with Boothman's team), and he suggested we compress the boot to alleviate the leverage condition created when the wheel travels through its arc/range. So, with a mondo clip and by compressing the boot, I headed back out on track, and this time it stayed in place. We tested it one more session that afternoon and then parked the car.

In the qualifying session the next evening (Friday night), when a co-driver managed to roll my car, as you can imagine, all of our first thoughts immediately went to a major concern that the axle had yet again popped out...It took 30-45 minutes for the safety crew to recover the car and we couldn't reach the driver on the radio to confirm what had happenend. While we all waited desperatley to talk to the driver for the report of what happened, we conjured up images of an axle that had pulled completely out resulting in significant failure. When the car was towed in with the rear end in the air, all of our hearts sank further, as we truly figured it was an axle related issue....Still not able to talk to the driver, we immediately crawled under the car while it was on the hook, and although the car was badly damaged, we were very relieved to find both axles securely in place. As bad as it was, we were somewhat relieved (in a twisted way) that it had not a mechanical failure.

As a result of all of our ongoing IRS issues over the last two years, which all surfaced during racing, we've decided to go back to a 3-link system on the new Competition Coupe....It's an unfortunate decision for sure, as many of the most highly regarded racecars in the world employ the use of an IRS system. Having raced Corvettes for a number of years, I appreciate the competitive advantage of an IRS, however, for racing purposes, we've determined it's not yet been developed to a point of reliability for extreme track use.

Thanks for creating this thread and keeping the discussion and troubleshooting moving forward. As many of you know, I am among the biggest fan of Factory Five Racing products, and believe highly in what they design and build. I also know that we're taking street-designed/engineered parts far beyond anything the engineers had in mind at the time, and subjecting these parts to extreme conditions. I'm glad they've acknowledged the problem, and not surprised they've discovered the axles to be too short. Although it's now retired from racing, I still will be running the #28 at track events and on the road in the future, and I'll be replacing both of the axles on the #28 Coupe for sure.

Karen

[CHOTIS BILL]

On my gen 2 type 65 I double checked the spacing from rear hub to rear hub and it was right on 59 ¼” which FFR had told me was correct.
I moved the driver side suspension through its travel to get the smallest side to side movement on the axle and it turned out it moved about ¾”.
I am going to make a 5/8” spacer and them double check there is no binding but I don’t think ¼” spacer is enough to fix the problem correctly at least on mine.

Bill Lomenick

[CraigS]

I hope Mr Masters got the dimension wrong cause 1/4 inch is NOT a fix. I don't have an axle to measure but let's say the total depth of the housing the trilobe fits into is 1.5 inches. We have several of the axles popping out but not all of them so the current axle length is right on the limit of the axle popping out. To get the axle into the center of the available travel, you would need an additional THREE quarter inch of axle length.that would center it at which ever point in the suspension travel they are popping out from. Then the question would be whether there is enough depth to allow for the rest of the suspension travel. So maybe a 1/2 inch of extra length would work. But then maybe the depth of the housing is more than my guess of 1.5 inches too. Either way, a 1/4 inch spacer will have the axle only 1/4 inch from popping out and that sure limits you alignment options doesn't it?

[Thomaswh4]

Any news when the new axles will be ready. I don't like the spacer fix

[lonestar]

Is there a way to verify if the CV axles assembled correctly? Measuring distance from the inner and outer joints, maybe? The nature of my concern is that after assembling the IRS, I noticed a little rotational (radial) play on both sides (maybe 0.5-0.8 degrees) when you rotate the hub. There is no axial play (the axle nut is torqued to spec, everything else in the rear end is assembled as per the FFR manual and torqued). If I push through the boot on the inner joint, I don't feel any protruding parts (rollers and bearings etc.) - which I guess is a good sign. It's just the fact that when I assembled everything, I did not check if the middle shaft is all the way into the inner joint (I doubt that if it should at all, no info in the manual about it). My apologies for potentially not naming things correctly (I'm not a professional auto mechanic) - I hope I was clear.
So asking for an advice here on how I can make sure everything is right (or not) before braking everything apart to verify. Big thanks!

[michael everson]

Lonestar. Is your kit the old T-Bird IRS or the newer Mustang? This only affected the T-Bird stuff. Been many years since FFR used it, thats why I ask.
Mike

[lonestar]

Lonestar. Is your kit the old T-Bird IRS or the newer Mustang? This only affected the T-Bird stuff. Been many years since FFR used it, thats why I ask.
Mike

It is 2015 Mustang IRS setup, part of the FFR Complete Kit. Brand new CV axles and spindles.