Loose rivet in Kwikee steps(SOLUTION)

[D_E_Bishop]

I have a set of Series #32 Kwikee Steps on my rig, the bottom left side drops significantly more than the right side when you step on them. I have found that the top step on the left side has a loose rivet(see photo A). I believe that the body of the rivet is 5/16” in diameter but because the bitter end has been peened with a X punch it is impossible to measure accurately unless the rivet is removed.

In the photo, "A" is the peened end of the rivet tenon sticking out beyond the offset part of the pantograph, "B" is the frame of the top step and "C" is the washer between the offset piece of the pantograph and the step frame. The offset piece and the frame of the step are 1/4" steel.




I believe the rivet is a shoulder rivet with the frame of the step and the washer pivoting on the shoulder and the tenon of the rivet held stationary by the peening. I don’t any other way to hold the rivet tight to the offset piece and let the step frame rotate on the rivet.

Has anyone repaired a loose rivet or had one repaired in their Kwikee steps, if so, how did you remove the rivet and what did you use to replace it. My thought is to remove the rivet and replace it with a shoulder bolt with the other piece of the pantograph threaded and the threaded end of the shoulder bolt long enough to extend to outside of pantograph frame to use a nylon locking nut as a jam nut instead of peening.

I found this on the Lippert Website. My idea of a shoulder bolt is good and now I have the dimensions as well. Now to order a should bolt that will fill my needs. Too bad they have discontinued the kit.

[fourthclassC]

Wow, it is really great to see other folks besides me think about stuff like this. Not to mention I learned a lot about my electric step as it is the same one .... Suggest to all McMaster Carr has all the specific hardware, Fastenal and Grainger also.. Thank for all sharing all the great info.

[D_E_Bishop]

Mex, you are so correct. I made an assumption not in evidence. UNR threads are better than UN threads and exactly what I was looking for.

If my engineer father were alive he would have corrected me and referred me to a engineering standards book and then checked to make sure I had read the specs.

[MEXICOWANDERER]

Grade eight tend to have Radiused Rolled Root Threads - rolled not cut.

Rather than pien, a nylock nut works great. For absurdly rude vibrating parts a distorted Stover Lock Nut holds tighter than a nylock, meaning it does not rely on clamp tension. Stovers are sometimes used on pliers' pivot points.

Something a lot of people are not aware of: High carbon grade eight fasteners corrode significantly easier than common grade five. Even when they are plated.

I had to really learn how to hot rivet when I repaired Delco 50 DN bus alternators and on the extreme other end replace rectifiers in Hitachi, ND and Mutibishi alternators. Eight dollars bought 200% higher capacity diodes at 1/5th the cost

Anyway, used as shafts where shear resistance is important radius rolled root threads tend to fracture a lot less at the bottom of the thread than V cut threads.

[j-d]

Great Job!
Common 3/8 bolt and common 1/2 bushing make so much more sense than trying to source a shouldered bolt.
Let alone in 5/16! That size is just a turkey. And, 7/16 is even worse.
Common parts and only one hole to enlarge... Great Job!

[wa8yxm]

I bolted mine.

[MrWizard]

Nice work
I'm sure this info will help others

[D_E_Bishop]

Since May when I first posted this problem, I have done a lot of research on repairs for loose step rivets and a couple of days ago decided to just take it apart and fix it.

First I tried grinding the peen off and driving out the rivet, didn't work so I drilled out the rivet in stages up to 5/16. I was careful not to drill through the rivet and damage the hole, then it drove out with a drift punch.

The hole for the shoulder is 1/2", the rivet shoulder is 1/2" x 1/2". The part of the step the shoulder fits is 1/4" thick plus the thickness of the step cover. This allows the use of a 1/2" metal washer to ride on the should and keeps a space between the step and the frame.

The hole in the stair frame is 3/8" in diameter and the frame is 1/4" thick. Both these holes appeared to be uniform and without any wear.

The method I chose to make the repair was to use a 3/8"-16 x 1.5" grade 8 bolt, a 1/2" OD x 3/8"ID x 1/2" sleeve, two washers and a nyloc nut. The difference in the feel of the steps is amazing.

I used a Grade 8 bolt, washers and nut because I have found that mild steel bolts with rolled threads tend to be significantly undersized and Grade 8 bolts, in general have cut threads. In my opinion Grade 8 were not necessary for strength nor to prevent wear. LCI used a phosphorous bronze bushing in their repair kit plus the shear force is nowhere near being great enough to require the Grade 8 bolt, I used it just for a better fit for the sleeve.

Looking at the rivet, it seems that it was peened of center which caused the shank to deform unevenly and was tilted to one side. The shoulder did not seat completely on the step frame but was on an angle. the wear appeared to be on the shoulder of the rivet and not to the mounting hole.

[Chum_lee]

D.E.Bishop wrote:

Chum lee wrote:
Since you have a choice when you buy the replacement bolt, whatever size you decide, I would suggest that you buy a grade 8 bolt instead of a softer bolt since it is loaded in shear and subject to rotational wear. Common hardware fasteners aren't the best choice. Reaming/drilling out the existing holes to a consistent size/clearance would also be a plus if you want the repair to last and rotate cleanly.

Chum lee

Isn't that pretty much what I said in describing the possible ways of doing it. I believe Kwikee used mild steel in building the steps and the rivets are mild steel.

Yes very true, they are mild steel. And now you know how long the original rivets last. If that is acceptable, replace the rivet with like and kind.

Chum lee

[Pangaea_Ron]

I'm not sure that shear values of non grade 8 bolts is an issue, but is a good idea considering the quality of non-rated foreign made bolts.

The off the shelf strength of a 1/2" diameter bolt in single shear is 8,717.5 pounds. A 250 lb. person stepping on the edge of the step assuming a 24" moment arm would result in a 500 lb. load. This is a pretty simplistic analysis, but suggests that the strength of the bolt is probably not an issue.

Edit: A rough estimate of the dynamic v. static loading should probably increase that value by 2.5 which would then be approximately 1,250 pounds, and would probably account for my 6'-5" son launching himself out the door and bouncing down the stairs.

[D_E_Bishop]

Chum lee wrote:
Since you have a choice when you buy the replacement bolt, whatever size you decide, I would suggest that you buy a grade 8 bolt instead of a softer bolt since it is loaded in shear and subject to rotational wear. Common hardware fasteners aren't the best choice. Reaming/drilling out the existing holes to a consistent size/clearance would also be a plus if you want the repair to last and rotate cleanly.

Chum lee

Isn't that pretty much what I said in describing the possible ways of doing it. I believe Kwikee used mild steel in building the steps and the rivets are mild steel.

[Chum_lee]

Since you have a choice when you buy the replacement bolt, whatever size you decide, I would suggest that you buy a grade 8 bolt instead of a softer bolt since it is loaded in shear and subject to rotational wear. Common hardware fasteners aren't the best choice. Reaming/drilling out the existing holes to a consistent size/clearance would also be a plus if you want the repair to last and rotate cleanly.

Chum lee

[D_E_Bishop]

To all that have replied so far, thanks for the input and here are things I have considered;

Removing the existing rivet and drilling out to accept the smallest bolt possible. That is evidently a ½” bolt. My idea was to only drill the offset bracket out to 15/32” and then tapping for either ½” – 20 or 28 and using a ½” bolt with a smooth shank that is 3/8” long in order to prevent over tightening and then using a jam nut.

Drill and tap the bracket for smallest sized tenon I could get and the step frame for what ever shoulder diameter I can get. And also adding a jam nut on the threaded tenon.

As the mod mentioned, there are several things to look out for, not the least of which is has either one of the holes been worn to out of round.

I guess that at this point what I need to do is, remove the rivet and then decide which of the possible solutions I will employ.

If anyone has additional ideas please let me know.

[haddy1]

I have been able to reduce the "rattle" in my steps by backing up the rivet with my 10# sledge hammer and striking with my heavy ball peen hammer. That is a temporary solution that will probably give way to the bolt/lock nut fix.

[MrWizard]

1/2 inch diameter bolt
Good info
Thank you