Projects Upper rear shock mount question

For those that are using Pete and Jake kits. My rear cross member is a tube. Where are you welding the little triangle tab? I guess I could weld it flat against the tube in the middle. Or maybe I shouldn't use the tab?

 

Do the instructions give you a distance apart or a degree to lean them on?
I would use the tabs.

 

30 degrees is pretty much the standard set up. HRP

 

Instructions are for a 32 frame with different rear cross member. Your 30 degree reference is talking about the inboard lean of the shock itself, correct? I'm talking about where to weld in the tab on the cross member. I cant weld it on the bottom edge of the tube because it will interfere with the spring travel.

 

I wouldn't use the tab,,I would drill a hole in the center of the cross member and weld the the tubing that the bolt goes through in the cross member,,allow enough spacing where there will be no interference with the spring. HRP

 

Yeah that's what I was thinking as well.

 

OK so I have a piece of DOM tube I want to use for my upper mounts. There is about a 1/16 difference between the inside diameter of the tube and my bolts. Is this ok or do I have to have a better fit? Seems like it might wear? Sorry this my first go around with building my own **** just want to be sure before I weld these in.

 

If it were me, infact i've done the same thing before with my wishbone mounts.. I got some solid round bar, and machined out the center until i was able to drill it with the exact size drill bit for the bolt that was going through it. It went in with a fly**** to spare and was such a perfect fit.

I have to build rear shock uppers like yours sooner or later..and thats how i'll be doing it.

 

Do you think these bolts would wear if I used this tubing?

 

Your tubing should have the same ID as the size of the bolt as over time the size difference will result in a failure. I've used a P&J crossmember and it had the tubes welded thru it?

 

Yeah thats pretty much what I thought. I ordered 7/16 inside diameter and they sent me 1/2 inch ID. Go figure.

 

If you ordered 7/16'' then you should send it back, they should make good on your order.

A bolt in single shear is bad enough, but one with a sloppy fit will definitely fail.

 

Yep I'm contacting them. I started to think I could just get a 1/2 inch diameter shoulder bolts as well.

 

I know that 30 degrees is common for shock angle but they work better the more straight up they are mounted. With them mounted at an angle the further that they are compressed, the less shock travel you have compared with vertical axle movement so the shock rate falls off (same story with springs on coilovers) right when you really need it to increase to avoid bottoming out on big bumps. Mounting the shock closer to vertical thus lets you run what is effectively a softer shock and ending up with the nearly the same rate throughout its travel. It is a win-win situation as the car will ride better over low amplitude bumps and not bottom out on bigger ones.

Roo

 

baspinall -

Jeeze...it's NOT all dume and gloom for .06" fastener to tube i.d difference...!
You gave more of a chance of not getting both sides in the "same" place, drilling the holes straight and welding properly thAn the slightly large clearance.
You are only going to gain a few thousandths. Hell, the different fasteners that are available may make up some of that clearance.

These aren"t coil over shocks...!

Just do your best as far as the alignment, welding and with the shock fastener "tight"....I'd bet you'll have MANY miles of problem free driving.
Just think of all the rest of the ch***is/car with things that you may question. People have gotten away with MUCH worse.

This is comming from a current mechanical engineering background that has built several cars, modified many more.

Mike

 

Well I decided to use this tubing will just find different bolts. Mike - I see your point. Thanks for the input. Guess I thought if there was any wiggle room it would eventually wear on the bolt. Either way it shouldn't be to hard to find a dang 1/2 diameter grade 8 bolt. Not sure why I was freaking out.

 

1/2 bolt fit into your shocks

 

No I'll be looking for a 1/2 shoulder bolt with a 7/16 threaded end. Hope they make them ......

 

Here: https://www.mscdirect.com/browse/tn...Shoulder-Screws-Stripper-Bolts?navid=12108828

 

I'll check that site out as soon as I get a length measurement. Thanks

 

If you really, really cant' get the right size tube to bolt fit I can "crimp" the DOM tube down on one of the crimpers at work. (8 radial crimp dies) We crimp hose ends on all types of hoses with a Machine rated at 100 TONs I have made many tubes or Boxed frames on model A's for drop out trans cross members old lever action shocks etc. so just PM me & I will do it for you the same day I get it. Hope I can help out a fellow HAMB,er

 

I have some tube that's 3/4 OD and 3/8" ID. Takes 7/16 tap or needs reamed for 3/8 thru bolt. I can send you some if that will help you out, I had to buy 20 feet when I needed 1

 

I mounted mine at 20 degrees off the vertical, a little bit better lateral stability

Make sure upper mounting is parallel to lower or you will chew out the bushings

 

You could also use a bushing on your bolt to tighten up the fit if you can't find a shoulder bolt.

 

I was always told 20% or 80 degrees was rule of thumb for shock offset. Of course unless it's a 4-link rear ladder bar setup, then it's straight up.

 

Wow you guys are incredible! I'm leaving for work then I have to pick up a buddy who just had leg surgery from a bike accident. When I get home I will investigate the bolt issue. If I cant find the right bolt I may take one of your offers up. Great reference for shock angles as well. A big help. I actually feel like I'm getting somewhere finally. A BIG thank you.

 

I would just buy the right size tubing from P&J and be done with it. I have bored out the tubing sleeve and make a shim to make it 7/16. Lots of work for very little gain. You can also purchase a quality shock with the correct size upper hole for your tubing. Good luck.

 

So long story short. P & J doesn't really sell the tubing but they said they would send me a foot. Good guys! Want to thank all the guys here that offered to help.
Mike VV - I understand your point. The other reason I am not using this tube is because its a 1 " OD. My rear cross member is 3 " and I wanted a smaller diameter DOM. I think that is more for looks than anything. The one inch looks really bulky if that makes sense. By the way - if anyone uses Metals Depot be aware that even if "they" mess up your order they will charge you a 30% restocking fee and you also pay return shipping. I thought that was pretty lame and told them so.

 

So I'm getting ready to drill my rear cross member to weld in a piece of DOM tube. Seems like I'm gonna need a pretty darn long bolt for my top mount doing it this way unless I lean the sock back towards the rear? Is it OK to have like a 6.5 inch bolt for the top mount?

 

I keep looking at the pics and wondering why not cut out the tube and weld in some square tubing? Is that not an option? Seems like it would eliminate the problem.