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Author Topic: Spare Tire Carrier and TPMS  (Read 7223 times)
MPlayle
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« on: April 19, 2011, 07:18:14 PM »

In the "Replacing Run Flat Tires" thread, I mentioned looking into adding a receiver hitch to my 2008 Clubman S and having a custom made spare tire carrier made.  Well, I am finally progressing on that project and figured it deserved a new thread.

I purchased the Curt hitch online along with the wiring converter to be able to hook up trailer lights if I decided to pull a trailer in the future.  I also found at local parts stores the type of connector housing I wanted instead of the 4-wire flat just hanging down.  I'll be installing those this coming weekend.  I'll take a few pictures of the process and post later.

I have also been working out the plans and dimensions for the tire carrier.  It will be hinged to drop down for opening the rear doors and likely have a "removable" bolt plate for the tire so other bolt patterns can be acommodated.  I'll post pictures when I get it made and have a cost estimate if others would be interested.

As my Clubman has the factory TMPS (Tire Pressure Monitoring System), I also looked into what would be necessary for having the spare included in the TMPS.   Huh
The pressure sensors are NOT cheap!  They can be found for about $40 each (aftermarket), but typically run over $100 each (aftermarket and OEM).   Shocked
In the process of researching them, I also read several discussions on other forums about some of the different issues with changing sensor on various systems.  Some support 5 sensors, some only 4; some require special tools to "register" the sensors to the monitoring computer, some don't.  Nothing on any of the big MINI/Mini forums had anything about the specifics of changing sensors on the MINI, nor whether 5 sensors were supported.  Even Mini Mania's tech people did not know!  I was able to contact the "MINI guru" at Tire Rack and found out the MINI's systems (they changed systems mid-2010) only support 4 sensors.  So much for the idea of having the spare on the monitoring system.  Angry


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BritBits
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« Reply #1 on: April 20, 2011, 09:35:44 PM »

Usually the senders in the tires only "send" when they're moving.   When I was working at the German repair place one of my better jobs was running the cars after the sensors had been replaced to get the system to recognize them.  Some of the Mercs needed 10-20 miles before they'd recognize and read.

One thing I always wondered.. since there are only a few companies making the sensors and the receivers have to allow for "replacements".. what's to stop your car from picking up the readings from the car next to you on the highway if battery dies in your sensor?

The Porsche dealer wanted $1k to replace 4 sensors on a customer's 911.  We got the sensors for something like $80 each and the tire shop at AveK and Park in Plano swapped them for $10/tire.  It's not rocket science, but it's better to find someone who's done it before.


Jim
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MPlayle
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« Reply #2 on: April 21, 2011, 07:24:37 AM »

Some of the sensors are activated when air pressure is applied.  The trnasmitters in the senders have very limited range (like the "bluetooth" headsets) and specific frequency ranges.

The programming of the receivers (car ECU) also seems to vary - some handle data from 5 sensors, some only 4.  Some require the sensor to be specifically registered to the system by serial number (requiring a special read/write tool) and some learn the new sensors automatically.

I agree that changing them is not rocket science.  Unfortunately, the car makers are not very forthcoming in how their chosen system works, so finding out the capabilities and limitations was a pain.

The MINI system apparently does not need "registration", but only handles data from 4 sensors.  The 5th has to be isolated while the system "learns" the first 4, then it ignores any others until made to "relearn".

Figuring out whether I could do what I wanted was a slight pain as it is apparently the opposite of what most folks want.  I wanted to add a sensor to the mix, most want to eliminate or bypass the system.
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BritBits
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« Reply #3 on: April 22, 2011, 08:56:24 PM »

I realize it's not as convenient.. but I've seen the tire caps that will toggle colors when the pressure drops below a set value.   Use that on the spare while it's "the spare".. when you swap the spare on the car the system should "relearn" that corner and recognize the spare in use.


Cheers,

Jim
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MPlayle
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« Reply #4 on: April 23, 2011, 11:15:39 AM »

Got everything installed yesterday.  Took pictures of most of the process.  Got a little "troubleshooting" of the electrical connections to do (not effecting the car's tail lights - not getting activity at the trailer light connection.  I suspect I don't have a good enough ground connection.

Will post the pictures and such Sunday evening or early next week.

Next step is getting the spare tire carrier fabricated.  Then getting a full-size spare.

Cheers,
Michael
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MPlayle
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« Reply #5 on: April 24, 2011, 04:49:37 PM »

I uploaded the pictures of the project to the MOT Media gallery.  Here is a link to the album:

http://miniownersoftexas.com/forum/index.php?action=media;sa=album;in=19

(Link should open the album in another window.)

Each picture has a brief description associated.  The installation instructions for the hitch itself are quite good and specific to the Clubman as this particular hitch is made to fit just the Clubman models (both Cooper and Cooper-S).

The tail light converter is required as the MINI tail lights use PWM technology to control the light intensity - single element bulbs in all positions.  It is a powered converter, so the MINI's electrical signals are just controls rather than actually driving the trailer lights.  This means a power lead has to be run from the battery in front all the way to the back and over to the location of the converter.  I made up a long lead with an inline fuse holder to run from the battery compartment to the back of the car.  After drilling a small hole in the battery compartment to bring out the lead, I dropped it under the car and zip-tied it along the mounts for other items under the car to the right rear wheel well area.  There I loosened some more of the screw-plugs that hold the fender liner in place and threaded the lead under the liner to under the right tail light.  From there, I zip-tied the power lead to the existing running light and license plate light wiring under the cross member and over to the power lead from the converter and spliced the two together (butt connector and heat shrink tubing).

I did a two-piece arrangement for the trailer connection as I did not want the 4-wire flat connector just hanging from under the car.  I got a 4-wire socket kit (Hopkins brand available at Pep Boys) and mounted that to the bumper with a 4-wire flat on the back side to connect to the converter's 4-wire flat.  Made for a nice and tidy arrangement.

Now to get the spare tire carrier fabricated.

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MPlayle
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« Reply #6 on: July 17, 2011, 10:05:57 PM »

Update: Finally have the prototype tire carrier!  The fabricator was working on it in between normal work projects, so took longer.  Plus we had several discussions on design aspects to make building it and using it easier and less complicated.  Also identified at least one place for improvement on any future builds.  I'm pleased with the results on the prototype model.

I sprayed its parts in Rustoleum primer and gloss black enamel this afternoon.  I've uploaded a few pictures of the pieces hung to dry in the album linked below.  I'll upload a few pictures of the assembled and installed unit tomorrow or Tuesday after the paint has cured.

 Grin

See the pictures here:
Tire Carrier Album

« Last Edit: July 18, 2011, 06:21:10 PM by mplayle » Logged
MPlayle
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« Reply #7 on: July 18, 2011, 06:22:00 PM »

Updated the album with pictures of it installed and the wheel mounted!  If there is any interest in one, let me know.  They will be custom made one at a time.  To make sure they are as snug a fit as possible, the interior measurements of your receiver will be required.  (The common receiver draw bar sizes have some "wobble" that would be unacceptable for this application.)

See the pictures here:
Tire Carrier Album

Cheers!
Michael Playle



PS> Does kind of reveal just how big the wheels really are.   Shocked
« Last Edit: July 18, 2011, 06:25:13 PM by mplayle » Logged
MPlayle
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« Reply #8 on: August 01, 2011, 09:39:18 PM »

I just realized I did not get a picture of the carrier in the lowered position.  I'll take one soon and add it to the album and post it in another update.

If anyone would be interested in one being made for them, let me know.  I'll work with the fabricator to get you one built-to-order.  (Anticipated cost $120 for the carrier.)  They are built-to-order and can be modified slightly for different sized wheels and receivers.  Required measurements if for different wheels from MINI: total diameter of wheel and tire, inside dimensions of receiver, back depth of wheel, and bolt pattern of wheel.

Cheers,
Michael Playle
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MPlayle
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« Reply #9 on: August 02, 2011, 07:18:54 PM »

Some pictures of how it works!  In the lowered position, the wheel is still held off the ground.

   

Cheers,
Michael Playle
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Angel
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« Reply #10 on: August 19, 2011, 03:49:44 PM »

You could of had a Continental kit.

You're right, the tire looks huge back there. I had visions of your MINI's front end lifting off the ground when you lower the spare on the carrier. Nice job!
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Angel
MPlayle
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« Reply #11 on: August 19, 2011, 04:37:35 PM »

The "Continental Kit" look was kind of the intent with being able to drop it in order to open the rear doors.  Since the Clubman basically does not get a spare and I do lots of highway commuting, I wanted a full size spare.  A full spare would not fit in the well designed to carry a 15" doughnut spare.  The only option was to come up with the carrier idea and have one made.  I've been very pleased with how the design worked out and its function.
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