Mastiff fuel tank keeps coming loose.

desertdawg

Member
I'm hoping someone might have an idea as to why my wife's mastiff continues to suffer a loose fuel tank. I've replaced the rubber mounts twice but the problem keeps coming back after about 20 or so out and backs. I sure would like to find a final solution as that tank is labor intensive to remove.
 

desertdawg

Member
Bought them from derek and donna and they have matched the originals and the service manual illustrations. The rear stand alone rubber always seems deteriorated and the metal button top is visible. I've read that NOS rubber won't hold up and I believe a vendor had posted that their new ones hold up, I just can't remember where I read that. Shovelhead kicker even spotted me an NOS set when I told him what had happened, great guy! On a side note, I replaced my EFI K9 throttle cables today so removed the S&S dual runner filter system and backing plate only to discover the throttle body throat really needed cleaning. Ambient temp sensor probe in throat was completely coated with PCV oil grunge. Have those of you that responded removed your Mastiff's fuel tank? This seems like an easy enough process. the rear mount engages the tank longitudinally and the forward cross mount rubbers only go in one way, with the slant of the rubber matching the slant at the tank mount
 

BWG56

Guru
I've removed my tank at least 6-8 times and I always put a little lithium grease on the rubbers before putting it back together and have never had a problem with them in the 10 years of ownership.
Here's a thought, for the front mount, there should be a flat type washers that goes on the metal bracket before the rubber, so the rubber doesn't push to far on the bracket, do you have those flat washer like plates? #19
 

desertdawg

Member
Yes, the little rectangular washers, I reinstalled those the first go around, and got them with the second complete kit I bought from shovel head. I too used a dab of lithium to ease the forward rubber installation. I'm pretty sure the aft mount has broken down again. I'll let you know
thanks.
 

PROFLYER

SWOLE
That's really odd. My wife also has an 06 Mastiff and I just replaced the rear mount. It's solid now and we've put 500 or so miles on it since I changed it out. Derek was telling me the new mounts they got were made with better rubber, as my K9 tank move up/down about 1/4" or more and needs a new mount. The new one they sent me is certainly a bit harder rubber than the old one.

report back and let us know what you figured out?
 

desertdawg

Member
Thanks, will do.
Please check your wife's bike for the voltage regulator that could catch fire.
Sharon's did and it scared the living bejesus out of us! When i ordered a new regulator it looked really junkie so i sent it back. Ordered one of the really nice ones Derek sells for the wolf and spliced in the proper connection. Then bought two more just in case.
 

phatchopper300

I just wanta ride
Bought them from derek and donna and they have matched the originals and the service manual illustrations. The rear stand alone rubber always seems deteriorated and the metal button top is visible. I've read that NOS rubber won't hold up and I believe a vendor had posted that their new ones hold up, I just can't remember where I read that. Shovelhead kicker even spotted me an NOS set when I told him what had happened, great guy! On a side note, I replaced my EFI K9 throttle cables today so removed the S&S dual runner filter system and backing plate only to discover the throttle body throat really needed cleaning. Ambient temp sensor probe in throat was completely coated with PCV oil grunge. Have those of you that responded removed your Mastiff's fuel tank? This seems like an easy enough process. the rear mount engages the tank longitudinally and the forward cross mount rubbers only go in one way, with the slant of the rubber matching the slant at the tank mount
Not to break in on this thread but can I ask where did you find the Throttle and Idle cable, Cant find any with the 45 degree bend on end and 90 degree on the other
 

Th3InfamousI

Administrator
Staff member
If the vr is stamped 05/06 those were the supposed problematic vr units come to find out it wasn't the vr but the circuit breaker , the recall was to replace the circuit breaker with a 40 amp inline fuse which many of us have done, call donna and Derek they sell it for $10 but the link below will show you what it is(by the way I'm still running an 06 vr)

https://www.ebay.com/itm/262954148908
Actually it was a small run of VR's installed in 05/06 models but the shops were replacing all the VRs and sending BigDog the bill so to save money they change it to adding a fuse.

Wasn't really a fix. But somehow it passed NHTSA. They went back and resissued the earlier recall with a fuse.

The issue was a possible warped bus bar on the VR so the fuse was just a cheap way out in my opinion. Really don't know how they got away with the fuse. Not all were bad but they didn't have a way to verify since they are solid state

If I owned an 05-06 I would just replace the VR for piece of mind..its only $100 and hell they are 10+ years old by now it's probably due.




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I'm hoping someone might have an idea as to why my wife's mastiff continues to suffer a loose fuel tank. I've replaced the rubber mounts twice but the problem keeps coming back after about 20 or so out and backs. I sure would like to find a final solution as that tank is labor intensive to remove.
May want to check the threads on the tank. I am not familiar with the mastifffs tank but if the bolts thread into the tank, you may possible have stripped threads. Also use blue loctite and make sure the threads are cleaned up and attention to torque specs.
 

BWG56

Guru
Well my 2009 k-9 voltage regulator also burst into flames! The stock shunt type regulators are not good. Go with a cycle electric voltage regulator and don't look back. Just my 2 cents! LOL111
Holy shit, I think instead of oil coolers mounted on the down tubes we should prolly mount some flame suppressors:rolleyes:
 
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