Spare Tire/Bike Carrier

[Bcborn]

Good day all,

I'm looking at modifying the rear bumper on my 2017 Winnebago 2106FBS Micro Minnie to accept my Swagman X2 bike rack. Our Winnebago sits low so mounting the 2" tubing to the top of the bumper tube will help with ground clearance for the bike carrier.

Option 1
Stiffening the rear bumper rather than replacing it with heavier 4" tubing. Replacing with heavier tubing would eliminate sewer hose storage.

Option 2

Replace with heavier wall tubing and lose sewer hose storage


Step 1

Wrap and stitch weld the existing bumper with 1/8 plate on at least the top and back for strength. This plate would be welded to the existing mounts at each end of the bumper. The existing bumper mounts that are bolted to the frame would be welded so an not to move at mounting holes.

Step 2:

a) Weld a 2" hitch receiver to the top of the modified bumper (rather than bolt).

b) Replace the current tire mount upright tubing with a longer piece (similar to other posting) and eliminating the existing bumper mount hardware. Length of new tube to allow tire to clear bike rack receiver. Weld this lengthened vertical tube, either on top or beside the 2" bike rack receiver that was previously welded to the bumper tube.

Rebuild would mimic the Roadmaster tire carrier for RV design (but fixed upright).

Step 3

Replace my current Swagman receiver tube with a slightly longer piece so bike crank assembly clears spare tire when inserted into the bumper receiver (may require removing the pedal to minimize outward leverage).

Yes, doing all this will place more weight to the rear, removing tongue weight.

This a good thing as I'm having to move a lot of gear to the rear of the trailer and run the truck empty to keep the truck within GVWR range and the trailer tongue weight closer to 12%

My question here is; Has anyone that has put a tire carrier on their existing bumper and experienced sag, determined where the sag came from (twisted the 4" bumper tubing or elongated the frame mounted bumper attaching bracket at the Huc Bolts.

I'm wondering if the existing huc bolted frame mounted bracket is ample strength if welded to the frame to prevent sag. I'm sure wrapping the thin walled tube bumper will eliminate twisting of the tubing itself.

Feedback please.

Thanks,

Lyle

[Bcborn]

Here is another thought;

Place a piece of Hollow Structural Steel (2 x 3 min - 2 1/2 x 3 1/2 max) in behind the original 4" bumper and weld it to the inside edge of the original bumper Support Channels (see attachment) and stitch weld it to the top and back of original bumper for extra support.

Shown is a piece of 2 x 3 HSS showcasing how it would sit behind the original bumper and were the receiver tube would sit on top and get welded to the top of the new 2 x3 and the original bumper..

Next would be to weld the vertical edge (inner and outer) of the 4" bumper support channel to the Z frame as shown near the huc bolts.


The vertical upright of the tire carrier would get welded to the top of the new 2 1/2 x 2 1/2 receiver tube. The current tube is 2" OS, but likely 14Ga material. Thinking a tube 1 1/2 square out of 14Ga would save space and provide adequate support.

The shown receiver tube will not he as long as shown. Likely extend past original bumper by 1" - 3" Max as the tire will be inset as far as possible.

Any engineers, fabricators here that can provide feedback?

[Fred 2106DS]

Originally Posted by Bcborn

Good day all,

I'm looking at modifying the rear bumper on my 2017 Winnebago 2106FBS Micro Minnie to accept my Swagman X2 bike rack. Our Winnebago sits low so mounting the 2" tubing to the top of the bumper tube will help with ground clearance for the bike carrier.

Option 1
Stiffening the rear bumper rather than replacing it with heavier 4" tubing. Replacing with heavier tubing would eliminate sewer hose storage.

Option 2

Replace with heavier wall tubing and lose sewer hose storage


Step 1

Wrap and stitch weld the existing bumper with 1/8 plate on at least the top and back for strength. This plate would be welded to the existing mounts at each end of the bumper. The existing bumper mounts that are bolted to the frame would be welded so an not to move at mounting holes.

Step 2:

a) Weld a 2" hitch receiver to the top of the modified bumper (rather than bolt).

b) Replace the current tire mount upright tubing with a longer piece (similar to other posting) and eliminating the existing bumper mount hardware. Length of new tube to allow tire to clear bike rack receiver. Weld this lengthened vertical tube, either on top or beside the 2" bike rack receiver that was previously welded to the bumper tube.

Rebuild would mimic the Roadmaster tire carrier for RV design (but fixed upright).

Step 3

Replace my current Swagman receiver tube with a slightly longer piece so bike crank assembly clears spare tire when inserted into the bumper receiver (may require removing the pedal to minimize outward leverage).

Yes, doing all this will place more weight to the rear, removing tongue weight.

This a good thing as I'm having to move a lot of gear to the rear of the trailer and run the truck empty to keep the truck within GVWR range and the trailer tongue weight closer to 12%

My question here is; Has anyone that has put a tire carrier on their existing bumper and experienced sag, determined where the sag came from (twisted the 4" bumper tubing or elongated the frame mounted bumper attaching bracket at the Huc Bolts.

I'm wondering if the existing huc bolted frame mounted bracket is ample strength if welded to the frame to prevent sag. I'm sure wrapping the thin walled tube bumper will eliminate twisting of the tubing itself.

Feedback please.

Thanks,

Lyle

Lyle, We carried 75 lbs on our rear bumper using a 2" receiver bolted to the top of the bumper in addition to the spare tire the first year we had our MM. Our bumper started to sag after that first year. Our sag was coming from where the bumper tongues are Huck bolted to the frame. The bolt holes appeared to be starting to elongate letting the bumper sag, we didn't have any issues with the bumper welds. Here's a picture showing the bumper sag and where the bumper tongues are Huck bolted to the trailer frame.

This problem led me to add Lippert 3 1/2" diamond torsion axle riser kits and a 2" receiver bolted and welded to the MM's frame.

Fred

[Bcborn]

Originally Posted by Fred 2106DS

Lyle, We carried 75 lbs on our rear bumper using a 2" receiver bolted to the top of the bumper in addition to the spare tire the first year we had our MM. Our bumper started to sag after that first year. Our sag was coming from where the bumper tongues are Huck bolted to the frame. The bolt holes appeared to be starting to elongate letting the bumper sag, we didn't have any issues with the bumper welds. Here's a picture showing the bumper sag and where the bumper tongues are Huck bolted to the trailer frame.

This problem led me to add Lippert 3 1/2" diamond torsion axle riser kits and a 2" receiver bolted and welded to the MM's frame.

Fred

Thanks for that info Fred, mine looks to have dipped so very slightly with just the spare tire carrier. You will note their is not a true 90 degree angle between the end of the frame and the bottom of the C channel.

Re jacking bumper into place and welding C Channel at the lip between the Z frame and the bumper C channel will take care of any more sag there.

Attached is a photo of a couple trailer bumpers coming detached at the bumper welds.

[bostonmary]

I am going to add wheels to the bumper because of low clearance. Wow,those pictures tell a story. Guess I won't be carrying my ebike on the back. But I got to try the wheels. My bumper may snap the other way!

[RocknRoll]

There are a few threads on this topic if you do a search. I'll surmise that you've already sifted thru them and decided to proceed anyway.

Below is a simple rear bumper bike "rack" that distributes the weight. Price is also reasonable; however, you may need to relocate the spare.

https://www.amazon.com/Swagman-Appro...7&sr=8-14&th=1

[Bcborn]

Originally Posted by RocknRoll

There are a few threads on this topic if you do a search. I'll surmise that you've already sifted thru them and decided to proceed anyway.

Below is a simple rear bumper bike "rack" that distributes the weight. Price is also reasonable; however, you may need to relocate the spare.

https://www.amazon.com/Swagman-Appro...7&sr=8-14&th=1

Thanks for the feedback.

Yes, been through a lot of posts and the general theme is not to hang anything off the bumper. I believe this is because the bumper material is so very thin and tears away from the frame mounts. Thus the reason I'm looking for frame mounted alternatives that owners have utilized that place the carrier above the OEM bumper.

Our 2017 Minnie doesn't have the ground clearance to utilize the typical Curt adjustable frame mounted hitch with receiver under OEM bumper. The 2017 requires spacer blocks to raise the trailer and at a cost of $500+ Canadian, I figured their must be other options.

The only above bumper option I have seen is with replacing the 4" square tubing with heavier gage steel and then bolting the receiver to the top. Doing so, you lose the sewer hose storage as the hose fittings will not fit the inside dimensions of heavier wall 4" tubing.

[RocknRoll]

Originally Posted by Bcborn

Thanks for the feedback.

Yes, been through a lot of posts and the general theme is not to hang anything off the bumper. I believe this is because the bumper material is so very thin and tears away from the frame mounts.

That is just one of the challenges. Another is weight distribution and how it will affect handling, specifically with a shorter TT. I personally tested this with a cargo rack (total of 100 lbs.) and a welded receiver and confirmed it is a major concern.

You mentioned that you have a Swagman X2. I believe the only RV approved rack from that mfg. is the TRAVELER XC2. For liability reasons, I hope that is the one you're referencing.

Good luck.

[Marine359]

I definitely would not put a bike rack on the bumper. The bumper is only good for 75lbs. The inertial moment of bikes jouncing up and down on a rack could damage the buck bolts or the welds. I’d never sleep again if bikes fell off underway and killed somebody. IMHO, the only safe way to mount a rear rack is by welding a 2” receiver hitch to the frame. Not an inexpensive proposition. We try to carry as little weight as possible in the truck bed, so we have sufficient payload remaining to mount our bike rack on tonneau crossbars. We put the heavy stuff in the pass-thru. We weigh in at 10# under Rear GAWR, and 20# under GVWR with 550-575# on the tongue. Bikes get dirty, so must be washed down regularly and coated with anti-rust spray.

[Bcborn]

Originally Posted by RocknRoll

That is just one of the challenges. Another is weight distribution and how it will affect handling, specifically with a shorter TT. I personally tested this with a cargo rack (total of 100 lbs.) and a welded receiver and confirmed it is a major concern.

You mentioned that you have a Swagman X2. I believe the only RV approved rack from that mfg. is the TRAVELER XC2. For liability reasons, I hope that is the one you're referencing.

Good luck.

I agree with Jim welding to the frame is the best and safest way.

It a Swagman XTC4 that I cut back to make two 2 bike units.

https://www.swagman.ca/products/xtc4-hitch-mount

Welding the 1/8" thick steel OEM Bumper Channels to the frame will take care of that part ever being an issue and plenty strong enough for 1000lbs. The next step is to build off that and continue with the strength.
If not I will build special brackets to hang off the frame in front and behind the body support bracket and then come up behind the OEM bumper to weld the 2 x 3 tubing to (see attachment).

The OEM bumper at 14Ga is not strong enough to hang off of. If the 14 gage tube is replaced with 11 gage it will be strong enough, but you will lose sewer hose storage.

Thus the reason I'm looking at building a strong sub structure behind the OEM bumper that will allow a top mount receiver with built in strength.

Obviously no one has gone to this extent. As a Journeyman Metal Fabricator, labour is free, If paying someone to design and build this you would be looking at no less than $500.

I was hoping someone went down this road and had a sample.

Currently I have too much tongue weight and thus had to move much of the contents from the passthrough to the bath and over the axles in the aisle. Putting weight at the back will allow me to move contents back into the passthrough and maintain a tongue weight similar to Jim's. With 3500lb axles and a 7000GVW the trailer rides better with more weight on axles.

I will post pictures as I move forward.

Thanks,

Lyle

[Bcborn]

Here is a drawing of my original plan, welding the Bumper attaching C channel front and back to the Z frame, then welding the 5 foot long approx piece of 2 x 3 (rectangle shown by dotted lines) between the brackets and flush with the top of the OEM bumper.

The support channel as referenced is the tapered channel that goes from the frame to the outer edge of the trailer wall.