I bought an 86 FXR with a freshly built motor 100" S&S cases, heads, pistons, blanced and honed crank, S&S super G with thunder jet, compresion release, oil lines to the heads, TP Engineering tranny case with Baker 6 speed overdrive, Techcycles pro 2"open belt, and tech cycles starter. This is the fastest harley I have ever ridden, it is truly unbelieveable, raced my buddy who sold me the bike and I kept right up with his V-rod night rod, so he sold the night rod and bought a v-rod muscle and hopped it up. I cant wait to race him now.

Here is my issue. Bike seems to keep breaking the effin bolts from the primary case to the motor, also broke a bolt from the torque brace to the tranny. I now have to get them all out and fix it. Prior to me buying the bike it kept breaking the bolts from the motor to the tranny, so they machined out the tranny to accept nut and bolt like a softtail. Bolt immediately snapped again (granted it was when I raced the v-rod) so I replaced the left side one with an ARP bolt, it hasnt broken but has come loose twice. I think its because it didnt have enough space to grab on to the nut, I think I was able to tighten it down good now.

So my question: I hear that these broken bolt issues are a common problem with the FXR and I have a feeling it has to do with the rubber mounted situation its got going on. This happen to any of you? I really need to solve this and get my burnouts on....

I truly fell inlove with this bike and gotta sort it out.

 

does it brake the engine to transmission bolts as well? i have one thats doing the same thing!

 

Thats how it started, breaking the engine to tranny bolts, then I put ARP bolt to replace the broken one, it has not snapped, but now all the primary to engine bolts are snapping.

 

I would venture to guess that you'll have to replace all the mounting bolts with ARP bolts. Otherwise, you make one strong and the next weak one breaks. Then the next weakest link will break.

 

Upgrade the rubber mounts and makesure that the engine/tranny are aligned, then make sure that the driveline is in the chassis straight and true. This will usually stop most of those problems.

 

i have replaced all the bolts, all of the motor mounts, and swing arm bushings. everything seems to be alligned properly and am still having this issue has anyone tried the (race brace) ?

 

Where are you buying your nuts and bolts? A lot of crap floating around these days. Not using stainless are you? I would be hunting downs some good grade 7 bolts.

 

I just put Grade 8 bolts in my primary. Are you over torquing the bolts? Manual calls for 18-25 ft lbs. Mine had grade 5 bolts but my FXR is rigid mount. (1988 motor to a E84 Tranny) but the front 4 bolts are smaller than the rear 2(5/16-18 vs 3/8-16). Have you pondered tapping the front to 3/8-16 like the rear?

 

the carlini torque arm/screaming eagle race brace will help with your problem.

The Op refers to brace so he's got one it looks like.

the torque arm stiffens the drivetrain, reducing vibration, improving handling and helps to keep the primary case from cracking.

I have one on my FXR, had one on the bagger I sold. and have a new in box for touring models for sale


Mike

 

one of the bolts broke on my torque brace too. motor and tranny are straight and true. motor mounts look good. I am going to try using Cadmium. "Screws meet Military Specifications (MS) and National Aerospace Standards (NAS). They have a Class 3A thread fit, a minimum Rockwell hardness of C39, and a minimum tensile strength of 180,000 psi." From McMaster.com