Roxor Rear Bumper

[SMF]

In the middle of the rear cross member (aka bumper) are two threaded, M12-sized holes for attaching aftermarket bumpers and hitches. The eight or so other smaller threaded holes on the rear cross member take standard M8 1.25 thread pitch bolts without problem. Contrary to initial appearances, the M12 holes, however, do not accept M12 1.25, 1.5 or 1.75 threaded bolts. M12 bolts look to be the right size and will start, but then no go further without cross threading. It appears that these two holes maybe BSW (Whitworth) threads. I'm sure that these holes are not contaminated by machining debris, but are threaded differently. BSW threaded bolts are unobtanium in my part of the country, so I have not established that these are BSW threads. My dealer was unaware of any such situation and said his go-between with the factory thought these were regular metric threaded holes which just needed to chased a bit. I'm thinking that's not the case, at least in my case. I could always retap the hole, I suppose. Has any one else had this experience? Here's hoping I'm dealing with a one off situation and that all your bumper holes are metric standard. Appreciate any insight.

 

[RoxorSE]

In the middle of the rear cross member (aka bumper) are two threaded, M12-sized holes for attaching aftermarket bumpers and hitches. The eight or so other smaller threaded holes on the rear cross member take standard M8 1.25 thread pitch bolts without problem. Contrary to initial appearances, the M12 holes, however, do not accept M12 1.25, 1.5 or 1.75 threaded bolts. M12 bolts look to be the right size and will start, but then no go further without cross threading. It appears that these two holes maybe BSW (Whitworth) threads. I'm sure that these holes are not contaminated by machining debris, but are threaded differently. BSW threaded bolts are unobtanium in my part of the country, so I have not established that these are BSW threads. My dealer was unaware of any such situation and said his go-between with the factory thought these were regular metric threaded holes which just needed to chased a bit. I'm thinking that's not the case, at least in my case. I could always retap the hole, I suppose. Has any one else had this experience? Here's hoping I'm dealing with a one off situation and that all your bumper holes are metric standard. Appreciate any insight.

Four of my bolts wrung off. I had to purchase new ones. I was following torque specs. I'm thinking of adding two more 3/4 inch bolts. I'm a little suspicious of the strength of the setup.

 

[RoxorYooper]

In the middle of the rear cross member (aka bumper) are two threaded, M12-sized holes for attaching aftermarket bumpers and hitches. The eight or so other smaller threaded holes on the rear cross member take standard M8 1.25 thread pitch bolts without problem. Contrary to initial appearances, the M12 holes, however, do not accept M12 1.25, 1.5 or 1.75 threaded bolts. M12 bolts look to be the right size and will start, but then no go further without cross threading. It appears that these two holes maybe BSW (Whitworth) threads. I'm sure that these holes are not contaminated by machining debris, but are threaded differently. BSW threaded bolts are unobtanium in my part of the country, so I have not established that these are BSW threads. My dealer was unaware of any such situation and said his go-between with the factory thought these were regular metric threaded holes which just needed to chased a bit. I'm thinking that's not the case, at least in my case. I could always retap the hole, I suppose. Has any one else had this experience? Here's hoping I'm dealing with a one off situation and that all your bumper holes are metric standard. Appreciate any insight.

I had the same experience when putting on my homemade hitch. I thought it was just paint at the time and just tightened them on but it took a lot of torque. I was a little worried about breaking the tack weld of the nut but all worked out.

 

[SMF]

This is such a trivial aggravation that I'm reluctant to resurface it. It would seem that mine, however, isn't the only Roxor out there with the two rear bumper bolts that are slightly out of metric/any easily recognizable spec. It is possible to torque in 12mm x 1.75 (coarse) thread pitch bolts, at the risk of breakage and a cross-threaded mess. Going this route, if there is resistance, it would obviously be wise to first chase the threads with the appropriate metric tap/rolling bolt. In fact, as noted previously, the Roxor factory rep insists these are 12mm holes. Maybe that's true, just not mine. I'm no machinist but, at least most times, I can successfully screw in a light bulb, usually on the first try. This shouldn't be much more challenging, but may not be quite so straight forward in some instances. First, I cleaned the threads of metal filings and factory grease. I then tried a socket head cap bolt (grade 8 equivalent) 1/2 in BSW (British Standard Whitworth) thread, made in India, no less. They worked a whole lot better than my 12mm attempt, not completely smoothly, but at no risk of wringing off the bolt like I experienced with the 12mm. A few forwards and reverses and perfecto. Does this mean the holes are BSW threads. I don't know, but suspect maybe. I've heard of a few others with similar problems finding proper fitting bolts for these two holes have used bolts from the factory aftermarket Roxor hitch. I've never seen the Roxor hitch in person so don't know whether those bolts are BSW threads or 12mm. Tried to order just the bolts from my dealer, but am told that these particular Roxor hitch bolts are backordered and will not be arriving soon. (But if they're standard 12mm why would finding them be such a big deal?) Buying the hitch for two bolts seems beyond nuts. BSW threaded bolts are uncommon here. I eventually found what I needed (two socket head 1/2 in BSW bolts 1 1/4 in long) at an out fit called British Metrics in Maryland, at an affordable price. This all got me to wondering that since British/BSW fasteners were in their heyday post WWII and hung around into the early 70s, could it be that is how they ended up on an India-manufactured Thar/Roxor frame -- throwbacks to earlier times. Who knows, but that's the trivia I've discovered and, rightly or wrongly, surmised along the way. HTH someone out there.

 

[Woodsman74881]

I started to make a hitch for my Roxor, but then the dealer gave me a sweet deal on the factory set up. In the factory package there was a bolt that was used to clean (or re cut) the threads on the 12mm holes. I don't know what the pitch is, but after using it, the factory supplied bolts that came with the hitch went right in.

 

[SMF]

Thanks, Woodsman. Good to know.

 

[txroadkill]

My on the Rox bumper came with two 12-1.25 cap screws for those holes. Not even close on the threads. I went and braved the Black Friday crowds today and bought two 12-1.75x35mm bolts and a tap. Chased the threads and all was good. I tried a 12-1.75 bolt in those bolt sizing things with sample nuts and bolts for thread sizing. The 12-1.75 went in fine in the 1/2-13 nut. When I saw that it became a no brainer to just chase the threads out to 12-1.75 like Roxor thinks they have and has you do for their hitch.

 

[SMF]

Yep, 12 x 35 mm 1.75 thread bolts are the easiest/best way to go after chasing the threads -- NBD, aside from the added hassle of running around to find the correct tap and fasteners. 1/2 in x 1 1/4 BSW socket head cap bolts also work well (socket heads with the OTR rear bumper since hex heads are a bit large), but Whitworths are a lot harder to find than metric. Clearly Roxor is aware of this minor quality control aggravation and it could/should be addressed at the factory -- by at least tapping the holes for 12mm-1.75 if not plugging them with a couple of correctly fitted bolts.

 

[GPG]

You know I've made a receiver hitch that just goes on the inner 12 m m + 4-8 mm bolts and when I stood on it granted I'm a little heavy there was a lot of flex in that inner bumper body support. I made a wider bumper plate that goes all the way to the holes near the frame rail then bolted the receiver hitch on top of it now it's very solid.

just thought I'd pass along my findings there's just not enough strength for a simple receiver hitch that doesn't get out to the frame rail area.

GPG

 

[RoxorYooper]

You know I've made a receiver hitch that just goes on the inner 12 m m + 4-8 mm bolts and when I stood on it granted I'm a little heavy there was a lot of flex in that inner bumper body support. I made a wider bumper plate that goes all the way to the holes near the frame rail then bolted the receiver hitch on top of it now it's very solid.

just thought I'd pass along my findings there's just not enough strength for a simple receiver hitch that doesn't get out to the frame rail area.

GPG

View attachment 7182 View attachment 7183

I redid mine too and extended it the full length of the rear bumper plus I added a 4 way flat trailer plug.

 

[Grump Fish]

I ended up just drilling some holes and mounting a Smittybilt bumper made for a TJ. Worked great. The inner four holes go through the reinforcement plate behind the stock bumper plate.

 

[GPG]

Was there a plug and play available for the flat 4 Spade trailer connector?

 

[RoxorYooper]

Was there a plug and play available for the flat 4 Spade trailer connector?

Yes if you have the XTC turn signal kit.

 

[GPG]

Cool thanks

I guess if I ever get my turn signal kit I will then order a flat for spade