Studs vs. bolts

[Grumblebuns]

I'm almost done with the M/C swap out on my S2, just need to reinstall the linkage box assembly. What a pain in the ass this turning out to be, struggling the past week trying to get it in one last time. I've had it on and off several times during the M/C change out with little issue. For some reason I'm having some difficulty this time.

I'm thinking if using studs to secure the linkage box to the inside backing plate. Are studs as strong as bolts and should they used for this application?

If the studs can keep the holes in the backing plate aligned, I will probably use the studs to support the linkage box and swap out the studs one by one with bolts. The next time I do this, I'll get the right length studs for permanent use.     

[gideon]

My linkage box was frozen and rotten underneath. I was thinking that I would rebuild without a linkage box. It doesn't seem like a good solution to introduce an extra linkage.  Have you considered this option?

[Grumblebuns]

My linkage box is in good shape so I'm going to keep the box in place. Without the box, you will probably have to use a M/C with a remote reservoir due to the steering rack interfering with the reservoir. You can use a spacer, similar to the one that the twinks use but then it may intrude into the space for the spare tire.

[BDA]

Spare tire? Are you still using a spare tire?! 

[EuropaTC]

I'm thinking if using studs to secure the linkage box to the inside backing plate. Are studs as strong as bolts and should they used for this application?

Most of the studs I've come across on cars are plain mild steel (exhaust studs & engine block items mainly) whereas bolts come in different flavours and strengths. So as a universal "can I use a stud ?" I think the answer "maybe" but it's down to the type of bolt you're replacing.

Bearing in mind I don't have a car with this sort of arrangement and I'm in pure guesswork mode, then I think you'd be ok in this situation.

The bolts are taking the weight of the assembly (not much) and the tensile load from you pressing the pedal as hard as you can.  That's usually taken as somewhere between 100-150lbs, factor in the 4.3 ratio of the standard Europa pedal arrangement and we're looking at what, 650lbs tensile load over 2 bolts ?  That's pretty low in the grand scheme of things so I'd be surprised to see HT bolts specified for there.

Having said that, is there enough metal to hold a stud securely in place there ?   What I tend to do in similar situations where I'm just making life easier for myself is to tack the bolt head onto on oversize washer with a flat on one side that jams in place to prevent it turning or a custom plate which links two bolts together.  I don't know if that would work here but if there's not enough metal thickness to take a stud then it's an option.

Brian

[jbcollier]

It's 16g sheet metal.  You could spot weld in a bolt to make a stud.  What I would do is braze/weld a length of steel to link the two bolts.  That will make them more likely to stay in place, and easier to tighten the nuts as well.

[Grumblebuns]

Spare tire? Are you still using a spare tire?! 

Good question for a poll but yes, my S2 came with a spare Dunlop 155HR13, probably the same vintage as the car. No cracking in the sidewalls. If it holds pressure, I'll put it back in as a spare.

Thanks Brian for your input. The S2 linkage system uses four bolts to secure the linkage box to the chassis with an approx. 1/4" steel backing plate. The tensile load will be distributed over four studs and the relatively thin steel back flange of the linkage box. From your estimate of the load on the bolts, substituting same quality studs seems to be acceptable.

What I'm probably going to do is use studs long enough to have enough threads sticking out the rear of the backing plate to locktite a nut. I've attached a photo of the backing plate the studs will thread into. 

[EuropaTC]

Looking at that backing plate I think you'll have no problems, and more to the point you'll have a much easier job should you need to pull it apart again. I didn't realise there was such a substantial backing plate, I bet Chapman didn't realise that was in there, he'd have thrown a fit !   

[SwiftDB4]

I did what John C. suggested. Spot welded bolts into the backing plate. Have had that for over 20 years with no problem.

[Grumblebuns]

At this point it will be easier for me to use studs. I have four Gr 8 studs on order, overkill I'm sure for this application.   

[skippopotamus]

Hi Grumblebuns, please double check that lower control arm nut.  I don't like how the threads aren't getting into the locking part of the lock nut.  Maybe it's nothing but...

[4129R]

Hi Grumblebuns, please double check that lower control arm nut.  I don't like how the threads aren't getting into the locking part of the lock nut.  Maybe it's nothing but...

I had the same problem with the 3/4" nut that holds the anti-roll bar drop links on the top front wishbone studs.

I drilled the nut through the stud and out the other side, and fitted a split pin.

The washers I used were thicker than the originals, the nut was wider, there were still enough turns left on the thread, but the Nylock was doing nothing.

The first nut/stud took ages to drill, the second took about a minute.

[BDA]

Since the A-arm pivot shafts are in shear, half height lock nuts are a good solution when there isn't enough length to fully engage a full height lock nut.

[Grumblebuns]

I did notice the nut being fully threaded while doing the M/C change out. The opposite side is in the same condition. It looks like the PO may have used shorter pivot pins in the past. I'm thinking of drilling and safety wiring the nut but I like the idea of using half height lock nuts as BDA suggests. Thanks for the reminder.

[GavinT]

The nut in pic also appears to be a flanged nut. Wouldn’t be surprised if that explains some of the extra thickness.

Perhaps consider an “all metal” lock nut which is shorter than a standard Nylock?
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