MOTOR MOUNTS

[craig haymaker]

WORD OF CAUTION : This tip is for you owners of the LS engines. And it may even be narrowed down to the "cammed" bikes, and in particular the 485 ! You motor mounts guys & gals.
At 8605 miles, I have a hairline crack, running parallel, all the way around and just above the only weld, on the upper right side mount. It is recommended that your motor mounts & fasteners are 'ed occasionally, especially on the cammed bikes & trikes. This is due to the result of the shaking effect of the "lope".
During my occasional motor mount fastener checking, I have always found that if one of the four (2-upper & 2- lower, all front) were lose, it was ALWAYS in my case, this particular mount's fastener that was lose ? The torque to the right I assume. Sorry for my typical looong dissertation but that's just Craigie.
Edit: I removed my statement about how I felt this should be covered under warrenty. Boss Hoss has been so fair with me, over all my bikes, that was unfair on my part !

[Bhilldw0111]

I don't think it is just 485 engine. If they are the same as the ones on the ZZ4 that attach to the intake, they break rather often. There is not very much steel ( or aluminum in the earlier ones) so they are not very strong.

[hogv8]

I like a few others fabricated front motor mounts that clamp around the front frame down tubes and bolt to the front of the engine block . I don't think this set up will ever be a problem .

[CanuckHoss]

I like a few others fabricated front motor mounts that clamp around the front frame down tubes and bolt to the front of the engine block . I don't think this set up will ever be a problem .

Hopefully Rick sees this thread but a few good pictures Jack on here and an email to Rick at the factory...I believe they are more open minded to changes than before...

[Ron Radulski]

I like a few others fabricated front motor mounts that clamp around the front frame down tubes and bolt to the front of the engine block . I don't think this set up will ever be a problem .

Hogv8, Could you show us some photos of the mounts you're talking about?

[CanuckHoss]

If you are a member of the other Forum you can go to the link below and see Jeff's fabricated motor mount..I could not get the picture off and post here..maybe someone else can??

http://www.v8bikeriders.com/forums/show ... tor+mounts

[hogv8]

It's kinda difficult to get a good picture of my front motor mounts wire the radiator in place but mine are the same style as the one's Jeff Hemperly made for Joe except mine are fabricated out of aircraft aluminum block and clamp around the down tubes similar to the ones shown and bolt to the front of the heads . Same idea anyway .

[2crzy]

I broke both my top mounts that bolt to the front of the heads to the down tubes. The bolts broke off in the little blocks that are welded to the down tubes. Had to split the bike to drill them out. Also made better mounts and retapped for a bigger Gr.8 bolts.
Then the two main chrome motor mounts that bolt to the block also had cracks in them. Replaced them as well recently.

[GordonBH]

Hi all,

I was looking at my mounts, they're still good but I'd like to get stronger mounts sorted. Any pics of your's Jack? measurements etc?

[3FOR2]

[hogv8]

I broke both my top mounts that bolt to the front of the heads to the down tubes. The bolts broke off in the little blocks that are welded to the down tubes. Had to split the bike to drill them out. Also made better mounts and retapped for a bigger Gr.8 bolts.
Then the two main chrome motor mounts that bolt to the block also had cracks in them. Replaced them as well recently.

502 Correct ?

[hogv8]

Hi all,

I was looking at my mounts, they're still good but I'd like to get stronger mounts sorted. Any pics of your's Jack? measurements etc?

Like I said mine are the same principle as the ones pictured however I also modified my Frame down tubes .For added strength I welded sleeves around the entire length of the tubes which increased the dia to 1 1/2" dia . I have no sketches or dimensions other than the clamps are 1 1/2" ID . All the rest had to be custom fitted because of the hole spacing on the front of the heads and the different distances between the heads and the tubes . Each one had to be hand fitted to ensure there was no stress being placed on the down tubes . Not a easy job
.

[2crzy]

No mine is an LS- SS bike with a ton of mods that I did to the bike to make a real bike out of it.

[Mikie v]

Here's my broken mount (front-right) about 8500 miles. notice the washers used as shims. After I installed the new one I made a spacer, fits better and looks better.

[hogv8]

Here's my broken mount (front-right) about 8500 miles. notice the washers used as shims. After I installed the new one I made a spacer, fits better and looks better.

I see there are spacers between the engine bracket and the frame bracket . As I said ,if the spacing between these two brackets is not perfect there can be stress applied to the brackets and cause one or the other to break .

[CanuckHoss]

Here's my broken mount (front-right) about 8500 miles. notice the washers used as shims. After I installed the new one I made a spacer, fits better and looks better.

That is quite a big gap in the break. How the heck could the motor even be mounted if one of the 4 brackets is that far off? Even if you welded that bracket how are you going to get the it aligned and the bolt back in????

[2crzy]

That's how they come from the factory, they use flat washers for spacers. Its a poor system and they don't even lineup correctly. I guess the frames are not exactly built the same. As soon as you get any stress on them they snap the brackets or the bolts.

[Imzz4]

I can't get the pics of some of the other motor mounts I've made because they're on a dead desktop downstairs. None were on the newer bikes. Being attached to the intake manifold bolts had its problems.
Some used 3 bolts ,and then 2 bolts in the heads and had not heard of any problems. This time ,I thought one bolt in the head along with a 1/2-13 threaded into the frame would allow for expansion and still give support with this setup. So far so good. The frame tubing is .125 wall with 1 1/4" tubing plug welded inside the downtubes.

[2crzy]

Well your mounts lineup without washers. But you only have one bolt holding into the head so it can flex without breaking. The SS is a lot different than yours.

[SQ4MN]

I will start out with the fact that the motor mounts on my 2003 BH have so far never broken. The only reason I can think of why any of them break is because the front down tubes on the frame try to flex a little when the bike forks bottom out or a big bump or pothole is hit at speed. The question I have is why do we have top motor mounts at all? The bottom motor mounts support the engine to the frame the way the engine was designed to mount in a car. I see no need or use for the top mounts. As a matter of comparison my V8 Chopper bike has no top motor mounts and none of them do. There has been no problems with frames cracking etc on the V8 Choppers and to my knowledge no engines have fell out of any of the bikes as of this writing.

[randy burkey]

I am no engineer ,But I think the more places the motor is mounted to the frame, The more the load is spread through the entire frame..In ideal conditions each mount would handle equal force. But I'm sure some mounts handle more stress than others..Thus failures happen..Does V-8 chopper have a bigger diameter frame, or a stronger strength steel?

[SQ4MN]

Randy the V8 Chopper frames have thicker wall tubing. I think the BH frames are still plenty strong enough to not need the top motor mounts to help keep the front down tubes from breaking. The engine doesn't need them to help keep it secured in the frame, I'm sure of that. If the front down tubes were to weak they would break anyway even with the front motor mounts. I'mont an engineer either but I'm pretty sure the designers Of Boss Hoss bikes wasn't one either. I base that on the mounting system with washers and a bolt for the way the top mounts are done. I think these bikes are not very engineered the way I picture an engineering analyst would do if he worked for Honda or some other big manufacturer. I think they were just made with whatever seemed like it should work and if it didn't they improved it enough to where it did. Most of these bikes were overbuilt in some places and not in others. The V8 Choppers are the same, Stan is no engineer. The bikes work pretty good for those crazy enough to want a Chevy motor in a motorcycle.

[Imzz4]

I'm sure Ricky has this on his huge "plate" of issues to look into. But I want to add this too. Some of the earlier frames also cracked at the top shock mounts. Some then had theirs modified with gusset plates or fabricated "triangulation rods" that bolted in place at the shock bolt and passenger peg hole as a precaution. I don't remember who it was , but his post said he hit a large hole and the frame broke at the shocks, and caused the seat pan to move forward enough to knock the dist cap off. That shut the motor off immediately and he got off the road ok. Scary stuff but worth bringing up if its still the same design.

[SQ4MN]

I think Adrian posted the factory fixed that several years ago. Do you have an opinion about why the top mounts are needed?

[CanuckHoss]

I'm sure Ricky has this on his huge "plate" of issues to look into. But I want to add this too. Some of the earlier frames also cracked at the top shock mounts. Some then had theirs modified with gusset plates or fabricated "triangulation rods" that bolted in place at the shock bolt and passenger peg hole as a precaution. I don't remember who it was , but his post said he hit a large hole and the frame broke at the shocks, and caused the seat pan to move forward enough to knock the dist cap off. That shut the motor off immediately and he got off the road ok. Scary stuff but worth bringing up if its still the same design.

I believe the 2001 and up frames had the gusset in the rear section in front of the shock mounts...fixed the problem...