Bumper Mounting Points

[Alpine 1789]

I was working on my rotisserie today and have discovered that the bumper bolts on my S3 have been replace, and not very well. IIRC, the originals are nuts welded on to a U-shaped piece of steel that is attached to the square tube that goes to the frame. (Is this correct?) It is hard to tell without doing some grinding, but I think the current ones are just nuts welded into the tube.

The new nuts appear to be very solidly attached (meaning they will be a pain to remove), but the PO made no attempt to be sure they both pointed straight ahead. The one on the right points out to the right, while the one on the left points up and left. They are not so far off that I don't think I'd be able to properly mount bumpers (although I have not verified that yet), but they certainly make attaching the rotisserie a challenge.

I am weighing four possible actions at the moment:

1. Assuming that I can attach a bumper straight, leave it alone and do nothing. I am pretty sure that I could compensate on the rotisserie mounting in order to keep everything parallel.
2. Remove the old bolts and weld in new ones. Like I said, I expect this will be a PITA, but I am sure it could be done.
3. Assuming they are ok, remove the bumper mounts from my parts car and attach them to the S3. I have no idea if this is even possible. Is it?
4. Make new mounts, as close to the originals as possible, and use those.

Any advice/recommendations will be appreciated.

 

[64beam]

Hi Jim,

I just had a look at the Tiger mounts and the nuts that are used to mount the bumper bar bracket are welded into frame above the jack points. I have taken a picture to show what I am explaining.

Regards, Robin.

 

[SIVAllan]

My camera just went haywire so will try and post my SIV pics later.

But the bracket seems the same although on my SIV one side has a huge lock washer, most likely not stock, and the other side has shim or flat washers, three I think it was.

Possibly the shim washers are correct enabling an out/in adjustment.

I didn't see welds.

Allan

 

[alpine_64]

Jim,

The mounts are originally a captive nut in the face of the frame rail. Ther are a absolute POS.. they are attached to a VERY thin face of metal and can be torn right out of the rail.. chances are that most cars have had them replaces or modified in some way after they got junked. I would consider fixing yours to be straight.. but make sure you mount them to a nice THICK bit of metal.

 

[Alan F]

When I made my rotisserie, I wasn't comfortable using those nuts to hold half of the car (plus I was missing one nut). On my car there is a thru hole further back on the frame rail (about 2 inches). I added two plates to the front rotisserie car mount that sandwiched the frame rail and ran a both through it. I also picked up the jacking point. The bumper mounts do seem to be at a bit of an angle. I just recently replaced the missing nut and fitted the bumper.

On the back I picked up the rear bumper mounting point, the jacking points and the rear leaf spring mount. This seems to work very well. It's been on it for 10 months and so far no issues.

Alan

 

[61Alpine]

Bumper Bolts

On my Series I the front bumper bolts were both just sitting in behind the U shaped piece welded to the front of the attachment point. It was a pain getting the bumper bolts in. I have to wedge the nut against the side and screw the bolt in, then line things up and tighten. Bumper is plenty stable even though the nuts are not welded. On my Series II the nuts are welded in.

 

[Bill Blue]

Jim, I'd trial fit the bumpers you plan to use. If they will bolt on, don't change anything. When making my rotisserie, I inserted 1" angle iron into the jacking points with bolts into the bumper anchors, then welded the whole mess onto the rotisserie arm. Had to disassemble with a hacksaw. But I figure what the hey, it is a one time thing anyway and it was very solid. Really didn't need the bolts as the jacking points were not parallel to each other and the 1" angle iron pieces were held captive after they welded onto the arm.

Bill

 

[Alpine 1789]

Thanks guys. I am using the rotisserie plans that were posted on TigersUnited.com (http://www.tigersunited.com/techtips/MenkeRotis/rt-MenkeRotis1.asp), at least for the mounting points, so the bumper bolts are only being used to hold everything together; the jacking points are where the primary load is supported. So, the weird angles the bumper nuts creates is certainly overcome-able. I think Bill's advice was the best option; I'll test fit a bumper before doing anything else.


BTW: the plans in the website specify 3/4" steel tube for the jacking points. I measured a jack and it is 7/8". I bought some solid 7/8" bar (they were out of the tubing), beveled the corners and it fits like a glove.

 

[skywords]

Jim
That Tiger rotissarie is OK if it is to be stationary but if you want to be able to roll out in the yard for the walnut shell blasters you will need one that is one piece with rails between both ends. I thought you were on the right track with the two engine stands and they can be connected with some large C channel from a scrap yard and the hole mess can be bolted together rather than weld. I have mine on large balloon caster bought from our favorite Chineese tool shop for next to nothing.

This made easy work for the blasters and when they were done all I had was some walnut shells in my yard. That Tiger unit with roller skate wheels will not let you do that and sure looks like a bunch of cutting and welding. FWIW

 

[Alpine 1789]

Update

I followed Bill's advice over the weekend and tried to fit a bumper. The first one I tried sat high on the left, but I wasn't sure that bumper bracket was straight, so I tried a different one (boy, I sure have a bunch of bumpers!). That one fit completely differently overall, but was still high on the left by too much for comfort. So, the mounting points need to be replaced.

I fabricated one over the weekend, and while it is far sturdier than necessary, I think it will work. However, before I mount it I need to make certain I have the nuts in the right position. I would simply base the new positioning on my SV, but I now know that those nuts have also been replaced: they don't look nearly as nice as the photo posted by Robin. As a result, I don't completely trust them for providing the correct positioning. I show a distance of about 1 5/8" from the bottom of the front valence to the middle of the bolt hole. Can someone confirm or correct this measurement? It also looks to me like the bolts point slightly upward. Is that correct?

I'll post photos of the new brackets when I am finished.

 

[skywords]

Jim, I'd trial fit the bumpers you plan to use. If they will bolt on, don't change anything. When making my rotisserie, I inserted 1" angle iron into the jacking points with bolts into the bumper anchors, then welded the whole mess onto the rotisserie arm. Had to disassemble with a hacksaw. But I figure what the hey, it is a one time thing anyway and it was very solid. Really didn't need the bolts as the jacking points were not parallel to each other and the 1" angle iron pieces were held captive after they welded onto the arm.

Bill

Bill that's the way to go using the jacking points. I am convinced you could assemble the entire car on the rotisserie using those points. After all they will support the weight of the car when jacking.