notch depth

[Duncan K]

I am going to be putting 7" drop springs in my 66. I'd like to be able to carry my dirt bike in the back so I am assuming I will need a notch for some extra clearance so I don't bottom out. What kind of notch depth am I going to need? I'd like to keep it to a minimum to maintain the strength of the frame. Probably going to keep it simple and do a pipe notch with plates on both sides.

[LVPhotos]

Wow a 7" spring drop? First a 1 to 2" block would help put the trailing arms back some away from front of fender. If that low I would do bags on Schrader valve then its adjustable.
As far as notch, the rear will hit bed before notch. So if a step notch is out so you can use bed. A simple 2" but I don't see how there is a 7" drop spring.

[Duncan K]

I'm looking for a 5.5, 7 drop overall. The 2" block, 5" drop spring makes more sense. I just measured and I have 10 1/2" from the top of the diff to the bottom of the floor, with a 7" drop that's only gonna leave me 3 1/2" of suspension travel. Is that going to be enough?

LV, how well do those bags hold air? How often do you have to adjust them?

[hewittca]

Originally Posted by Duncan K

I'm looking for a 5.5, 7 drop overall. The 2" block, 5" drop spring makes more sense. I just measured and I have 10 1/2" from the top of the diff to the bottom of the floor, with a 7" drop that's only gonna leave me 3 1/2" of suspension travel. Is that going to be enough?

LV, how well do those bags hold air? How often do you have to adjust them?

I am looking into notching my frame as well, but I'm just going to use a standard bolt in notch. In the process of figuring things out, I determined that under normal driving conditions I have 2.5" of travel in the rear. My drop springs (like pretty much all of them) aren't really meant for hauling stuff so even a couple hundred pounds puts me on the bump stops.

[LVPhotos]

I have had the rear bags on for years. I really have not had many road miles 2000 maybe while building and weekend use. The Firestone 2500s hold air very well a weekly check would be eyeball monthly psi check like tires. Here in LV heat and cold cycles I keep eye just because.
I will say again before cutting frame check rear to bed clearance. That added 2" notch might look good on paper but why cut frame if your not going to address other contact points.

[zachiatrist]

Speaking from experience in this matter.. a simple pipe notch will be plenty but someone above was right, you'll smack the pumpkin into the bed before the frame. Before I had bags, I had drop springs and 2" lowering blocks in the back and always hauled my Harley around no problem, which is much heavier than your dirt bike. I also have CPP c-notches installed, but you gotta cut a hole in your bed for the pumpkin before the axels will go very far up into the notches.. the hole was never needed with a spring setup... and I've hit some gnarly ass pot holes and dips with my Harley in the back and never spanked the bottom of the bed that I can recall. So all in all, you should be fine and dandy.

[Duncan K]

Just measured it up, 9 1/2 clearance between the axle and frame, 10 1/2 from the top of the diff to the bottom of the floor. Don't think it is worth cutting the frame to gain an inch. I'll just drop it and see if it bottoms. I suspect it will with only 2 1/2" of clearance. Might have to go the step notch route down the road

Zachiatrist, how many inch drop spring were you running?

[zachiatrist]

Originally Posted by Duncan K

....

Zachiatrist, how many inch drop spring were you running?

I was running 6" drop springs in the back. But I guess I should revise that I wasn't running the additional 2" lowering blocks until later on. But I was still able to haul the Harley with the blocks added. It was just a bit more squashy. If you're gonna do that, you should def put at least a c-notch in for safety. If the rear diff hits the bed, it will only make it bulge up a little bit whereas slamming the axle into the frame will make you pucker up a bit.

[The Rocknrod]

Originally Posted by zachiatrist

I was running 6" drop springs in the back. But I guess I should revise that I wasn't running the additional 2" lowering blocks until later on. ...

So you had an eight inch drop in the rear?

[zachiatrist]

Originally Posted by The Rocknrod

So you had an eight inch drop in the rear?

Correct. I had a pretty typical 5/6 static drop, and as I said, I later added 2" lowering blocks. So yes, 8" total in the back. But now I'm on Accuair elevel and lowered a hell of a lot more than that hah.