We have installed thousands of Pedders systems nationwide with great success. We have, however, had experiences with the nuts that attach the upper rear control arm to the knuckle, on maybe 5 or 6 vehicles (approximately .5%), coming off. We have been investigating the issue. Chrysler manuals do not list the nuts as 1 time use while on some of GM's similiar nuts they do and we have had no other nut/bolt issue with any of the other vehicles we do. But the OE nuts have an approximate 75in/lb (6-7ftlbs)interference fit between a new nut and the bolt. In the failures experienced the nut were gone. If it was simply not torqued correctly, the nut would not be missing due to the quench of the nut to the bolt. The OE torque of the outer bolt is 72lbft and is a grade 10.8 bolt and nut. Upon our investigations of this issue, we are seeing the quench on some of the OE nuts to be as low as 15-20inchlb, a 80% reduction in its quench. But we are only seeing a very small % of the nuts loosing their quench. We have chatted with multiple Chrysler dealers and have found 2 of them that replace the nuts due to them coming loose. Most, however, do not even stock the nuts. Since most Chrysler dealers do not even know how to check the bushings in the LX, I cannot trust the dealerships in general.
So we have done a test fit on some alternative methods. We will most likely be offering a nut kit that goes from a 10.8 bolt to a 12.8 bolt and nut assembly. These nut and bolts will allow us to torque to 100lbft from 72lbft OE. We will also be using a nyloc style re-useable nut, with an extra nut to double nut the bolts. This is most likely overkill, but since we are not 100% sure as to the failure of the nut, overkill is the way to go.
The picture above shows a OE nut and bolt and a possible replacement.
The issues of the nuts on the knuckle are unique compared to the other nuts in the rear. Here are the variables:
1. the knuckle assembly has a lot of up and down movement
2. Our Pedders bushings add contact to the nut washers. the OE nut and washer hardly has any contact at all
3. The OE nut washers are not flat, but dished.
Advantages of the hardware kit:
1. Higher torque rating from 72ftlb to 100 ftlbs
2. Washer contact is flat, which will spread a more even load over a larger area
3. hardware increased from 10.8 to 12.8, which add serious strength
4. New bolt will be approx 1/2 inches longer, allowing us to double nut the assembly. This will add a serious amount of redundant locking power.
.5% failure rating on a OE nut, that Chrysler says you do not have to replace, is not acceptable to us. We seriously strive for 100%
So when we have the hardware kits available, we will announce it.
In the interrum, those that are installing the arms, should measure the quench pf the OE nuts, and if they are nut at 75inlbs, then replace them. We also recommend using red loctite on all the nuts, after properly cleaning the threads
thanks
mike
dms
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