The Stovebolt Site Forums The Shop Area The HiPo Shop Scrub line for lowered 'bolts.....

So, how low is too low?

Used to be the cops would draw an imaginary line (or use a straight edge) between the bottom of the rim on one side, to the ground on the opposite side. This used to be called "the scrub line". If any part of the car, or truck, was below the line, it was illegal (remember Millner in American Graffiti stating that his ride height was completely legal and that the cop could check it if he wanted to?)

Has this changed? I've seen a couple of posts here recently that would suggest it has. Any thoughts??????

Seems anymore, they're more concerned about them being too high, like the lifted trucks with the bumpers at the hight of the roofs of most cars.

Here's a paragraph out of the NSRA Vehicle-Safety-Inspection Requirements...Joe


Scrub Line...........
Dual master cylinder recommended. On both the front and rear suspension of the vehicle, stretch a taut string from the bottom of each wheel rim to the bottom of each of the other three tires at the road surface. If any part of the steering, suspension, or chassis is below this string, the vehicle will fail scrub line test. Allow an additional 1/4-in. assuming the tire will not come off the rim if the tire should go flat. Items exempt from scrub line check will include body sheet metal, bumpers, exhaust system, oil and transmission pan.

Good info there, Joe. That confirms what I thought, but I sure wouldn't want my oil pan to come in contact with pavement as the NSRA requirements seem to permit!!!

No problem, what I do w/my cars/trucks when I get them that low is put just the rims on it & sit it on the floor to check everything.

As for them allowing your oil pan to hit, I would bet they are more interested in you stopping then if your motor will run or not when after that wild ride your on...Joe

This is a quote from Sid (Drapal) He does a really nice dropped axle. He has been old skool trained in doing this. I figure he knows what he is talkin about.
"Glad to hear you guys like my axles. 3" drop is a lot lower then people think. You got to be careful because you don't want to be plowing pavement with your axle if you have a blow out. If you are running tall wheels then that's a different story. To figure out your scrub line. With your truck setting normal
1. Measure from bottom of axle to ground.
2. Measure from bottom of rim to ground (tire side wall height)
3. Now subtract #1 measurement from #2 this Equal srub line clearance
4. Now subtract from #3 measurement the amount of dropped axle you want.
Answer equals amount of clearance you have if you blew out your tires going down the road. YOU WANT CLEARANCE!!
If you guys ever need any help please get a hold of me and I do my best to help you out....SID "

BigSix302; Thanks for your post. The method you describe was one of the reasons I was asking the question in the first place.

It seems to me that Sid's method, and some others I've read, assume that both front tires blow out simultogetherously, and that both tires come off the rims. A pretty unlikely scenereo.

If you lose air in one tire, the axle will have a slight lift advantage coming from the good side, I think that's reflected in the NSRA's method.

With all due respect to Sid, and I am running one of his 3" DA's, I'm going with the NSRA as Zookeeper described.