Visit The Dirt Forum for More Information

Author Topic:   best way to check leed
dirtywrench13
Member
posted June 22, 2003 07:43 AM
having a **** of a time setting leed in the dw-8.i can pick any point on the car, all the way into the frame stub,and the leed calculates to be half an inch to the right. but if i hook the bottom ball joint grease zerk and check the left side is an inch-and-a-quarter shorter.we restubbed the car 2 years ago and i just clipped the rearthis spring.according to dirt works its straight any help would be great!


mod4
Member
posted June 22, 2003 08:51 AM
Got any friends at Car Dealerships / Alignment shops ? Only reason I ask is that the new 4 wheel laser alignment machines are cool, we have access to one, and no matter what method we have used (Xing the entire car with scribe lines from the zerks, measuring pickup points, measuring hub to hub) - none of them repeat with the accuracy of a laser head. You can accurately measure really really small amounts of rear lead and rear steer (and be surprised how bent 9 of 10 9" rear housing tubes are, even new ones).
There are a few issues, if you run more then 3.5* of camber our machine doesn't like it (the laser beams don't meet right). But that wasn't really a problem for us, at least.
I'm sure there are a thousand other ways to check the squareness of the car, but as I said, none of them repeated each time perfectly and can measure hundreths of an inch of toe/thrust/etc.


dirtywrench13
Member
posted June 27, 2003 07:02 AM
dont need a friend in a dealership,i'm a ford tech in central iowa, in a 2-horse ,small town shop.when i leave i usually don't want to come back till i'm due to be back.i cant get the drivers(i have 2 cars)to haul to the shop.so we figure them out at home.the d-w 8 had some severly bent front end stuff after really close measuring and inspection.its time for a new chassis,but no moneyto buy one.the car is faster than ever with 4-z now trying to get it to quit diving to the bottom from mid corner,(he runs the high side).


HRT187
Member
posted June 27, 2003 07:21 AM
I assume you made sure the axle was the same length as the front or at least noted that it wasn't (if that's the case?). I ran across that problem years ago.

I find this method to work best:
measuring from the bottom wheel stud (with a zero'd angle finder across the top 2), set wheel bases the same

X-measure and adjust the rear laterally to get the measurements to match (if you have an adjustable front, this gets trickier) see footnote *X*

After setting the X's the same length adjust the RR forward to the desired lead.

The best way to measure this is with adjustable radius rods in place of the shocks to set the car at ride height, jackstands under the axle and control arms works but can be inaccurate and the jackstands can get in the way. Fergit all that string and jackstands around the car crap, I never understood that and it's only as accurate as the jackstand on the floor the way I see it.

*X* with an adjustable front (Torino or SLM) I think you need to rely on a scribe mark or jig holes in the frame. What I've done in a pinch is tied a string from zerk to zerk on the lower BJ and noted how it crossed points on each side of the frame. One of the few times I've thought one of them grid floor thingies was a good idea.

Hope to help anyone, and if you see a problem with my logic, please point it out, we're all here to learn something.

[This message has been edited by HRT187 (edited June 27, 2003).]

dirtywrench13
Member
posted June 28, 2003 08:31 AM
187, what u say makes sense to me anyway,my biggest delimma in the racing shop is that if i come up with a way to do something,the owner doesnt understand what i'm doing and we argue for hours on end about the right way to do it(he knows it all!!!).i've been flippin wrenches for 17 years,and it really gets on my nerves.he really hates it when i come up with something and dont discuss it with him before i use it. but i make more progress faster that way. thanks for your help!


HRT187
Member
posted June 28, 2003 09:58 AM
I started as a crew chief for my dad in my early teens, I had a ton of the same arguments as you with my car owner. The best way to do it is to be confident and do the work when he's not around. I made some huge adjustments that won us features that I and my crew will take to our graves... it's just better that way. It doesn't make your buddy a bad person, you just have to draw a line when you start to be counter-productive.


fastow
Member
posted June 29, 2003 01:15 AM
I read somewhere that the old Chevelle clips are lead 3/4 on the right front out of the factory. I also read somewhere you should measure off the engine plate. I measured my DW-8 everywhere and anywhich way I knew how, but the best numbers I came up with was by measuring the zirk fitting on the lower ball joints to the center of the weight jack bolts where the rear springs mount at the cup(my springs are on top). Hope this helps.


HRT187
Member
posted June 29, 2003 04:36 PM
I've used the zerk fittings before, and I don't see any real problem to it. I just like to see where the actual wheel is falling and the hubs are a little closer. Measuring from the axle housing isn't always that cool to me because the axle could be bent outside where the tab on the frame is (been therem done that). I don't have any experience with using square stock clamped to the frame, sounds interesting though, kinda a portable minijig. Measuring off the engine plate is different, not sure what makes that meathod work any better than anything else, except when including driveshaft angle.


devil wrench
Member
posted June 29, 2003 07:13 PM
HRT, you're method won't square a rear if you have any caster split.

fastow, I'm with you on the tabs.

fastow
Member
posted June 30, 2003 12:03 AM
quote:
Originally posted by devil wrench:
HRT, you're method won't square a rear if you have any caster split.



Ok well that's why I say you go right to the wheel hubs all the way around. I said I've used the zerk fittings before and the results weren't too bad.

Aligning to axle tabs is fine if you double check them to make sure all that is still straight. It's a great quick check at the track... don't get me wrong. I've got about 5 different ones on each side of the car that I use to constrain each part to check for square. Each time I scale the car I note these points. Just keep in mind that the axle can bend outboard of the tab.

What's your method??

[This message has been edited by HRT187 (edited June 30, 2003).]

BigBlueFord
Member
posted June 30, 2003 07:37 AM

Just for the sake of clarification. How about a definition of the term "LEAD".

Just want to make sure I'm on the same page with everybody else.

Good discussion.

Thanks

dluna
Member
posted June 30, 2003 08:49 AM
They are talking about static lead in the left and right wheelbases and the best way to measure it. So, leading the left would mean that the left rear tire would be closer to its corresponding front wheel compared to the right rears' (shorter left side wheelbase). Opposite when you hear leading the right rear (done to tighten the car, usually on dryslick). I hope this makes sense?!?

easy example: left side wheelbase measures to be 109 1/2" and the right side wheelbase measures out to 109...which means you are leading the right side by 1/2".

dirtywrench13
Member
posted July 01, 2003 06:43 AM
sounds like i started somthing here.i've found out through carefull examination and measuringthat my chevelle stub is leading the right side by 1/4 inch from the g.m. factory.ive also found that d-w is taking many steps to make a car that is fairly square to start with.if you go to dirt works web site you can get a printable tech guide that gives you all the starting points,and all you guys seem intelligent enough to finish it yourself,(i did ).


dirtywrench13
Member
posted July 01, 2003 06:56 AM
the way i figured this critter out was to measure lead as per d-w's instructions then figure out what was different in the front. as i have mentioned before this car was restubbed a year ago ,and it measured straight when we were done.when i was finishing the rear and setting up for our first night i noticed 1&1/2 inches left side lead. dazed & confused i went to the notes from last year. my best common point is above the rear lower a-frame mount.string &tape measure in hand i found the left lower a frame to be shot and the rest of the car to be true to form ,with the right side leading by 1/4 inch. hard thinking and telling the driver to shut up &go somewhere else paid off in the long run!!!!!


Back to the Archives