Jump to content

Can Am Defender Max Limited on 32" Rock-A-Billys


Toolboy
 Share

Recommended Posts

Well I got the shocks adjusted finally.  I bought a large filter wrench that looks like a set of channel locks that works great for adjusting the shocks.  

UPDATE:  I took 5 of us for a ride and the front tires did rub when I turned and hit a little bump.  So, I ended up putting on a 2" lift on the shock mount, which was really only a little over an inch.  I also clicked all shocks on the defender up to the 3 of 5 setting.  The ride is a little rougher but not bad.  I just wanted to update everyone as I thought I could get by with the 32" rockabillys at first without doing any lift or shock adjustments. The defender now sits as 16" clearance now both front and back.

  • Like 1
Link to comment
Share on other sites

On 3/12/2020 at 6:59 PM, Toolboy said:

Well I got the shocks adjusted finally.  I bought a large filter wrench that looks like a set of channel locks that works great for adjusting the shocks.  

UPDATE:  I took 5 of us for a ride and the front tires did rub when I turned and hit a little bump.  So, I ended up putting on a 2" lift on the shock mount, which was really only a little over an inch.  I also clicked all shocks on the defender up to the 3 of 5 setting.  The ride is a little rougher but not bad.  I just wanted to update everyone as I thought I could get by with the 32" rockabillys at first without doing any lift or shock adjustments. The defender now sits as 16" clearance now both front and back.

Did you have any pictures with the 32’s? 

Link to comment
Share on other sites

On 2/4/2020 at 9:15 PM, Toolboy said:

   I just changed out my stock rims and 27" 'big horns for a set of Sedona Split 6 bead lock rims and 32" Rock-A-Billy tires.  Each new tire and rim combo weighs in at 53 lbs.  The stock rear rims with the bighorns weighed 46 lbs. each.   So I figured I might lose some speed with the increased rotational mass.  However I was pleasantly surprised.  The machine still gps top speed on flat ground at 67 and will now run 70 down hill.  There is obvious speedometer error now but it also cruises better at 50 to 55 mph.  The new tires and rims fit fine even with the shocks on the softest setting.  No rubbing any direction lock to lock on the steering wheel.  The new tires are as quiet or quieter than the factory wheels.  I do notice a little more steering wheel wiggle at certain speed but I have not tried to balance each of the new tire/rim combos yet.  The machine looks as it should have from the factory.  Now it look properly proportioned.  I am sorry for not having pictures yet as it as dark when I finished tonight.  I took it for a 16 mile drive on the blacktop roads around my area and I can say I love these tires.  The power steering is not as strong (obviously) with the bigger tires, and there is slightly more road feedback in the steering wheel.  I am running 12-14 psi in the tires right now but will try up to 20 to see if it improves drivability even more.  This combo is going to be a hot ticket, looks and rides great.  

     I wanted to let others out there questioning what would fit and what would not, to know that this setup works great.  I will post picks soon.

Could you please tell me what kind of rpms you are getting? I’m on 32” Roctanes and only getting 52 mph and 5700rpms. 

Link to comment
Share on other sites

Two things happen when you change tire diameter, the increase in height of 5" changes the final gear ratio and the increase in tire rotating weight increases the load the CVT sees as it tries to accelerate the machine. If you did a drag race for a short distance between two machines: one with stock tires and one with the taller tires you would see that the taller tire machine is slower and cannot reach the same top speed as the stock tired machine.

The stock 27" tire would travel 84.78" in one revolution, the new 32" tire would travel 100.48" in one revolution. That means that your effective gear ratio is about 18.5% higher so right from engagement the CVT has to compensate by starting off in a higher gear, to better explain; in the days of the 4 speed transmission you are always starting out in second gear (effectively). Since the CVT dosen't have gears to select it stays down in the lower diameter of your primary clutch longer.

The addition of 7 lbs. of rotating weight per tire (7x4=28 lbs/7=4 hp) adds another 28 lbs of load that the CVT has to compensate for, so the CVT does this by staying down lower in the diameter of the primary clutch. The additional rotating weight makes the system react similarily to one that has 4 Hp less.

In summary the CVT system compensates for the change by staying lower in the primary resulting in a smaller contact area for the belt compared to a stock machine resulting in more slippage and higher belt temperatures. The driver has to apply more throttle to start and maintain a given speed so the engine RPM remain lower and the top engine RPM cannot be reached because the CVT is compensating for the additional load.

The only solution is to change the "shift ratio", which is the ratio of the engine RPM and primary clutch shift versus the resistance of the secondary clutch to allow upshift is to change the springs and helix in the CVT system. EPI performance, Outlaw and Airdam clutches have clutch kits based on tire diameter and intended use (trail riding vs mud, rocks or sand) that change the shift ratio to control belt slip(temperature) and allow engine RPM to be more balanced vs the load on the CVT. I have contacted EPI and Airdam and they will respond to your questions and recommend a kit that should improve the performance of your machine. The primary clutch (connected to the engine) usually gets a different primary spring which can affect your engagement and a different spring ratio that affects the final opening (when the primary clutch is fully shifted out) and the secondary clutch usually gets a helix with a different angle to help control upshift and back shift and a new spring that helps the system react better to the increased tire diameter and rotating load. The clutch kit guys do not easily give out start and finish rates on the new springs or helix angles because they consider that to be proprietary information.

If you do purchase and install a kit, please post it in the builds section along with your comments of what you like or don't like about it?🤔

Edited by Andystoy19
correct numbers
  • Like 1
Link to comment
Share on other sites

Andy, I don’t want to hijack this post but could you tell me why I’m seeing other defenders getting at least 6500rpms and over 60mph while I’m barely hitting 50 mph and 5700 rpms? I made a post about it but got no responses. 

Link to comment
Share on other sites

Stock machines with stock tires have reported top speeds of up to 70 mph, if a stock machine with 32" tires could reach 50 mph (indicated) the corrected top speed might be about 61 mph in your case at 5700 rpm? In my opinion that would be as good as you can expect for the reasons I stated above. Reported speeds will vary slightly as well because of elevation, flatness of terrain, temperature etc. 

A naturally aspirated machine loses about 3% per thousand feet of elevation so a machine at 3300 feet is about 10% lower on HP than a machine at sea level. The shop maual says 7000 RPM is where the engine makes max power.

In my case with 30" heavy tires I reached 50 mph indicated (58mph corrected and 2000' elevation) on a long run that might have been slightly down hill, that is why I am researching after market clutch kits to see if I can delay my upshift a bit and allow the engine RPM to increase a bit for the same speed which will reduce the belt slip and belt temperature a bit as well. The machine will become much more responsive with a good clutch kit than it is now with stock clutching.

If you still have the stock tires and rims switch back to them and see if your top speed increases along with RPM as others have reported, if yes than your machine is running well, the tires changed its ability to reach a higher top speed.😉

Link to comment
Share on other sites

On 3/22/2020 at 2:05 PM, Toolboy said:

I do but how do you get pictures to this site?????

When you open the reply message or quote message. The box where you type your message there is a CLICK TO CHOOSE FILES. Click on this and add photos from your library. 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.



×
×
  • Create New...