New 5 leaf springs, now out of alignment

[Meyer65]

Hi all,
So I finally got around to installing some 5 leaf springs I had lying around, as the 4.5 leafers I had, while in excellent condition, couldn't handle the horsepower and I got serious spring wrap/wheel hop on acceleration.

So anyway, everything went in without too much trouble, but now the car is out of alignment.

Did I do something wrong? The 4.5 leafs were standard eye and the 5 leafs are mid-eye, if that makes a difference.

Basically I am wondering if I need to crawl under the rear again and redo something or if I just need to take her in for an alignment at the wheel works?

 

[AzPete]

Did you tighten all the bolts with weight on the car/axle? You should. This can make a difference. Also, look at how the springs line up on the spring plates.

 

[blue65coupe]

measure, measure, measure again

Measure distance from fenders to check front/back/side distance. Spring plates also as Pete said. Measure everything before tightening and don't tighten one without the other. A little on each side at a time. It took me 4 or 5 times.

 

[Sluggo]

You changed the thrust angle. Pretty common when changing springs or rear ends.

Not much you can do now without the starting measurements.

Which way did the steering wheel go off center?

 

[Meyer65]

The cars pulls right now (if my wheel was straight) and left of center keeps her going down the road.

 

[blue65coupe]

You'll need to measure from center of front wheel to center of rear also. Can you tell if it's pulling from the front or pushing from the rear?

 

[Meyer65]

I did not notice if it was pulling from the front or pushing from the rear. However I do know that the car was aligned (insofar as it was tracking straight) before I swapped the springs.

 

[Anonymous]

Duane is actually giving good info for once :crazy...lots of measurements and you'll get it back right.

I'm more interested in the 4 1/2 to 5 leaf swap to eliminate wheel hop. I added the 4 1/2 leaf mid eye springs to mine and have never had any hop, even at the track with sticky tires. What kind of power are you putting to the ground?

 

[johnpro]

I'm more interested in the 4 1/2 to 5 leaf swap to eliminate wheel hop. I added the 4 1/2 leaf mid eye springs to mine and have never had any hop, even at the track with sticky tires. What kind of power are you putting to the ground?

Ditto. I cannot believe your car is putting out that much power. I have 4.5 leaf mid-eyes on my '66, which runs 14 flat on street tires. The reason it runs 14 flat, instead of mid 13's is because of all the tire spin I have at the line, and there is no wheel hop, and no traction bars.

 

[Sluggo]

The cars pulls right now (if my wheel was straight) and left of center keeps her going down the road.

That means that the right wheelbase is shorter than the left.

What Duane said.

What is going on is the rear is steering the car right because the rear is slightly more forward on the right......Hell lemme do a rendering real quick be right back

 

[Sluggo]

K I'm back with my rendering :crazy

This is exaggerated to help with the concept.

You'll notice that the rear is crooked :crazy
The rear is cocked making the left wheel base longer and the right shorter. This is steering the car right because it has to.
When you have the steering wheel centered the front wheels obviously are straight and are trying to go straight forward while the rear is trying to go left.

When you turn the steering wheel left, all four tires are now going the same direction, but now your center line is going left too.
Yes, your car is going down the road sideways. :hide2

 

[Meyer65]

Ditto. I cannot believe your car is putting out that much power. I have 4.5 leaf mid-eyes on my '66, which runs 14 flat on street tires. The reason it runs 14 flat, instead of mid 13's is because of all the tire spin I have at the line, and there is no wheel hop, and no traction bars.

Hmm that's interesting. Do you have a trac-loc? What's your rear end?

The rear leafs that were on there came from Canadian Mustang, according to the sticker (not Mustangs Plus like the 5 leafs). I had a receipt from the previous owner that installed them. At first I thought they were 5 leaf, but the 5th leaf was a few inches shorter than on my MP springs, so I deduced they were 4.5.

My best run at the track was 13.51 That was before I put trac-loc in, so needless to say I had a lot of trouble hooking up (street tires on 14" rims). I've never run with the trac-loc on (or the fuel pump in the proper place, for that matter). I have no idea what kind of actual HP I'm getting to the rear wheels, as I've never been inclined to pay for a dyno run.

Anyway, all I know is I had bad wheel hop before, but it seems to be taken care of now with the 5 leafs. Now if I could just get the car to go straight

So how do I alleviate the problem?

 

[Anonymous]

I know you directed towards JP, but here's what I have/experienced.

Old 3.70 gears just recently changed to 4.11, true trac locker running on crappy Dunlop qualifiers on the street and all kinds of R comps on track, 4 speed toploader. Mustangs + 4 1/2 mid eye leafs with poly bushings. I used to have under rides and now they are gone and I have a panhard bar. Not once have I had any wheel hop and it's not because I don't ever light the fire out of the rears :naug

Measure your rear end at various fixed places and you'll see where it's out of alignment. It's easy to fix once you do that. You can open up the locating holes just a bit (if absolutely necessary) to help out. Look at Sluggo's highly detailed professional drawing :crazy

Now, I will say before I restored the car and was driving on the factory, mega old springs, it would wheel hop bad, but never since the restoration. I just think that the ride is going to be a bit harsh with 5 leafs on the street. On the track they would probably feel great!

 

[Sluggo]

Best thing to do at this point is to measure center to center on both sides and try to get a better center on the rear.

You can also loosen the u-bolts and push the right side back and the left side forward then retighten and see what you got. Maybe you'll get lucky. You might need a helper for this. You want to make sure you are actually twisting to the right.

If you were closer you could bring it to me and I would put it on the alignment machine and set the rear toe. Not really adjustable but you can loosen the u-bolts and shift it around on the springs a little. Maybe you can find someone local the understands alignments (not just adjusting til' the numbers are green) that cares enough to swing the rear over where it needs to be.

Moving it even an eighth inch (if you can) on both sides will make a big impact.

If you just want the illusion that it's aligned you can turn the tie rods so the front wheels turn left. Then the steering wheel will be straight but it will dog track.

 

[Anonymous]

K I'm back with my rendering :crazy

Wow, that will definitely win an artwork equal of the Pulitzer Prize.

 

[Sluggo]

Wow, that will definitely win an artwork equal of the Pulitzer Prize.

Did it illustrate the point?

I can make one much more elaborate if need be :boohoo

 

[Anonymous]

Did it illustrate the point?

I can make one much more elaborate if need be :boohoo

No, no...it illustrated it well enough so that even Duane could understand it :bow

 

[Meyer65]

If I had to guess I would say the issue with the other springs is that they were not Mustangs Plus. Yeah they were 4.5 leaf, but they were significantly lighter than the MP 5 leafs, a lot more than I expected from a few extra inches of the 5th leaf.

As for the ride, the 5 leafs were off an old car I wrecked about 5 years ago. I drove on them for a number of years, so I was well aware of what the ride would be like. They are stiff, but not jarring. Actually, they're a lot of fun in the corners. For cruising the 4.5s that were on there were better, but wheel hop is just embarrassing, and I already had the 5 leafs. Honestly it's a little embarssing it took me this long to put them on (I had to dig for an hour in an attic that was 115 degrees with no ventilation, but that's another story).

Also, how do I know it was aligned properly to begin with? I noticed that the right rear tire was wearing on the outside, although if this was the product of being on a poorly aligned front and then rotated I have no clue if that's what the previous owner did.

Also, I get a wicked vibration above about 70mph that feels as though it is coming through the driveshaft, but does it especially when coasting and going downhill (can smooth out when on the gas). It's a vibration that gets worse the faster I go above 70. Could this be related to the rear end alignment or...?

 

[Sluggo]

As for the ride, the 5 leafs were off an old car I wrecked about 5 years ago.

Tell me it was not wrecked in the rear.

Also, how do I know it was aligned properly to begin with? I noticed that the right rear tire was wearing on the outside, although if this was the product of being on a poorly aligned front and then rotated I have no clue if that's what the previous owner did.

You don't. That's why you're gonna measure the wheelbase. Tires wearing on the outside would likely be a camber problem. If you have rear camber problems, you have big problems. For rear toe to cause tire wear (in my opinion) the offset would be noticeable. The left would be worn similarly because it would be running the same amount of angle as the right, unless the axle tube is bent on the right. Remember, short of a bent tube, any deviation from 0 degrees on one side will affect the other side equally.

Also, I get a wicked vibration above about 70mph that feels as though it is coming through the driveshaft, but does it especially when coasting and going downhill (can smooth out when on the gas). It's a vibration that gets worse the faster I go above 70. Could this be related to the rear end alignment or...?

Was that there before? Probably not related to the alignment of the rear. Did your pinion angle change? Vibrations when unloaded would more likely be diff related. Driveshaft issues usually cause vibration when loaded.

 

[blue65coupe]

Mark, FYI I didn't need that drawing to understand. I walk like that :crazy

Derek, hope it wasn't wrecked in the rear. As far as alignment, the typical shop probably wouldn't touch the rear. Measure center of front wheel to center of rear on each side and compare the numbers. Also measure front/back/depth of each rear wheel to the fender. You can probably eyeball both sides and see a difference. The vibration...are you sure it's coming from the driveshaft? Start measuring before you continue driving. As far as the 5 leafs, they aren't that bad. Put 'em on mine and it feels good.........till the car sputters and dies but that is a different story.