Technical Hardware for suspension etc.

I have a question for all you guys in the know.

As you may know I’m in the process of assembling my 26 RPU.

I’ve painted and chromed a bunch of stuff and now I’m wondering about the bolts for things like my rear suspension (5/8” ) on the rear wishbones and the upper triangulated bars (through the urethane bushings).

Along with that there’s the rear coil over mounts also 5/8” bolts.

My question is, would there be a problem with buying stainless steel bolts for those locations so that I can polish them up nice and shiny like the other fasteners that are also stainless?

 

I have an answer for......

 

Impatient aren't we.

 

Blue One, I don't recommend just going to the hardware store and buying their SS bolts for critical/stressed parts such as suspension. But if you get SS from somebody like ARP, I think they would be fine.
I have a lot of heartburn for the unbranded, made who knows where hardware store bolts now on the shelves, and don't use them for things like suspension. A career in the aircraft maintenance field as a machinist got real interesting at times when "bootleg" bolts somehow got in the system once in awhile! There was a big stink about some bogus "cone bolts" once, and we had to do a rather exhaustive hardness test on each and every one in the system, but they were extremely critical as four of these bolts held each engine on the plane
Anyhow, get quality bolts and they'll do fine if you are careful to use anti-seize. And that does bring up one point, with antiseize present, loctite doesn't work.

 

I'll have to look into what ARP has to
offer. Any other sources to look into ?
Do you have an idea of what grade of stainless would be suitable ? I can check with our local industrial bolt supplier.

 

Your my boy Blue! I polished a bunch of stainless bolts after grinding them smooth, I like that option best. If you buy those chrome plated bolts and nuts, chase the threads with a tap and dye or you will pay the price...twice.

 

So, are you using any stainless bolts for critical points mounting your suspension ?

Like you I’m trying to make things shiny.
I didn’t go as extensive as you did with my chrome and polish but I’m getting there

 

My quarter elliptical posie springs are attached to the frame with polished stainless bolts (7/16) as are the ladder bars and shocks (1/2) , top and bottom. I also used stainless on the pan hard rod on both ends (1/2).

Tonight, coincidentally, I finished polishing the 6 bolts that hold the QC cover on. I had to cut down 4" bolts to 3 3/4", run the threads and polish the caps. Takes a while but sure looks nice.

I use the chrome ones for spreader bars and acorn nuts, etc...non structural stuff. I may not use stainless for placement where torque settings are required as I am not informed enough as to their stretching capability but I'm not torqueing down ladder bars and shocks.

 

I put Loctite under the bolt head on stainless, haven't had one come loose yet....

 

I have used stainless in critical areas, never a failure. I wouldn't hesitate to do it again. Get a lot of the bolts from McMaster Carr.
I like polished bolts, but hate cleaning and polishing the heads, so I like to do it as quickly as possible. What I have found to work really well is a nylon mesh wheel for the bench grinder. Put the bolt in a drill, and use the wheel on the head, it sands of the letters quickly, and leaves a surface you can take right to the hard wheel of the polisher. Quickest and easiest way I've found.

 

I’m thinking that I would probably be fine with 5/8” stainless bolts for my rear wishbones and upper bars even for the coil overs.
They won’t be torqued just tight with nylock nuts.

 

I'm no expert on fasteners (though my wife says I'm nuts) but I think you will be fine.
BTW, there are no pictures on this page and my ADD is acting up.

 

I’m getting quite good at polishing
I bought a simple bench top polisher at harbour freight on one of my Texas trips. That along with the compounds and starting out with a flapper disc on my grinder makes getting black fingers easy
Polishing is fun

 

Larry, I attempted to have every visible fastener on my T polished stainless - I have minimal chrome and want the colored surfaces to pop. For all suspension bolts I used ARP. Totally Stainless has an excellent selection, but they don't tell you they're ARP - they just show up that way. You could order from someone like Summit for a lot cheaper, but it's not as easy to find the sizes you want. If I ever decide to pay that much $$$ for fasteners again, I'll use the Totally Stainless catalog to reference then cross reference Summit. I was unable to find an aesthetically pleasing 5/8" fastener in stainless. I bought some from TS but sent them back (they looked atrocious). My plan is to polish some grade 8 steel ones and clear coat them in hopes that holds up for awhile. Good luck.

 

Sorry but if you want pictures they’re on my build thread

 

What grade are all these stainless bolts we're talking about? You need to know what grade they are to torque them properly at final assembly. Yes, I believe every critical suspension/ brake bolt should be tightened with a torque wrench.

 

I wouldn't use ungraded SS bolts in high loaded areas (Suspension) although I've seen it done and those have gotten away with it. There is a difference in tensile and yield strength that makes ungraded SS bolts unsuitable for these areas. I would use Grade 5 but preferably Grade 8 steel bolts or graded SS.

....It is a common misconception that stainless steel is stronger than regular steel. In fact, due to their low carbon content, many stainless steel alloys cannot be hardened through heat treatment. Therefore, when compared to regular steel, the stainless alloys used in bolts are slightly stronger than an un-hardened (grade 2) steel but significantly weaker than hardened steel fasteners.... https://www.boltdepot.com/fastener-information/materials-and-grades/materials.aspx

 

ABSOLUTELY NOT!!!
https://www.hunker.com/13401271/stainless-steel-vs-grade-8-bolts

 

I knew someone would chime in with the type of info above. Yes, stainless bolts are not as strong as steel bolts, but are strong enough for the working load they see on a street driven car. I wouldn't use them on a purpose built drag car, but on a street car it'll be fine, but obviously all hardware is not created equal. Use quality stainless bolts.

It's like the argument about if drilling an axle weakens it. Yes, it does, but not enough to be a problem with the working stresses it sees.

 

Another vote for McMaster-Carr. All the hardware on/under my RPU is polished SS. Has been for over 10 years. No problems. Just don't buy cheap crap from Speedway, Summit, etc.

 

Stainless Bolts will gall and literally weld the stainless nuts to them when torqued.
You need to use CRC or WD40 on them.

If you want to polish them ,Polish up some steel bolts and get them zinc plated [polished zinc looks like nickel plating]

 

There is a huge difference in the bolt strength required when torquing a cylinder head bolt versus a bolt used in double shear. IMO, even a grade two 5/8” bolt in double shear would be more than sufficient in strength for suspension links.....(think Class IV and V trailer hitch receiver pins) not that I am recommending grade two fasteners. Just pointing out the difference in shear vs tensile loads.

Ray

 

That's what never seize is for, to prevent that.

 

Call Pete and jakes. Talk to jerry. He will explain why not to use. Cosmetics yes anything else no.

 

I broke two 1/2" Grade 5 bolts on the rear coil-over shock lower mounts. One when it was tied down in the trailer and the other when I went over some RR tracks one time.

Someone told me that Grade 5 would be fine. It wasn't. It went down on the rubber frame bumpers and I was able to limp back (about a 1/2 mile) without anything rubbing.

It was SCARY! Nothing but Grade 8 for me!

 

McMaster Carr has high strength stainless steel bolts. Always use anti seize compound on ss to prevent "galling".

 

Yep, anti-seize paste should be considered a must with stainless and titanium hardware. Fine threads are particularly vulnerable to galling. Learned this working in the aircraft industry years ago. We had critical assy areas where an inspector had to be present during assy. to sign off on paste, torque, etc.

Be very mindful of bolt grade on critical/suspension assy's where there is shear load such as trailing arms, leaf spring/shackles, etc. Crap hardware will shear off w/o warning.

Gardner-Westcott used to be a good source of stainless hardware. Haven't bought from them in many years though.

 

Most people don't hit post until they finish typing the sentence. Just having fun.

 

I gotta ask.........were they mounted in double shear or single? The majority of shock/coilover I see posted here and other places are single shear mounts. Big difference in bolt loading and bending moments..

Ray

 

I was typing using my TV remote while looking at the Hamb on my fancy new 55 " smart TV and got frustrated
So I hit enter and then finished my post on the computer
There's a learning curve to everything