5/7 or 4/6 deliemma

[cruisinthe34]

I've been ordering parts for the new '71 stepside, and I've arrived at two decisions and would appreciate input.

As a byproduct of converting to power front disc brakes, I'm looking at dropping the truck either 4/6 or 5/7. I am planning a static drop, so that leads to the wheel and tire size question, I'm looking at 18" rims or as large as 20". what backspacing and tire sizes can I get away with and avoid fender rub ?

Thanks in advance for the input.

[jondancer]

Just search the forum it's all out there. I'd go 5/7 when you want to go low , it's never low enough ! I went 4/6 , 5/7 , and now bags .

[cruisinthe34]

Thanks, I'm thinking 5/7, but not sure what effect if any on tire size between 5/7 and 4/6. I know I have to C Notch the frame in the rear for 5/7, assume the same for 4/6

[Blue/72]

My dad has a 5/7 static drop with no c notch and he is running 20s all the way around. It also has double adjustable qa1 shocks which really helps with the ride and the truck being so low.

[67ChevyRedneck]

ECE 4.5/6. I've scraped the front bumper a few times...

4.5/6 Does NOT need the frame notched. I've even hauled a few hundred pounds in the bed over crappy roads. Just cut down your bump stops or get new ones.

['68 Newtricks]

I want to emphasize tire rub. That's the part of the OP question that I'm currently thinking about. I've got a 4.5/6 drop on 20s and tire fitment looks similar to the green truck above.

[67ChevyRedneck]

Originally Posted by '68 Newtricks

I want to emphasize tire rub. That's the part of the OP question that I'm currently thinking about. I've got a 4.5/6 drop on 20s and tire fitment looks similar to the green truck above.

I had 15x8's with 4.5" BS all the way around on my truck, and it looked to me like the front tires would rub with a good bump. Never really drove it with the 8's on the front though, so I bought a set of 15x7's with the same BS (4.5") for the front and the tires are nowhere near rubbing.

[cruisinthe34]

Thanks for the input. I'm surprised to hear no 'C' notch required, for the rear drop.

[CC69Rat]

One thing you want to check before you buy your wheels.

The 67-Early 69 rear end housings were 1.5" shorter than the late 69-72. This can make your break your wheels either fitting or not.

Steppers are tough. The fenders are not as big, and with a later housing it's going to be even more difficult. With a 5/7 drop on a stepper it's going to be critical.

If you measure the rear end housing, have a buddy / wife hold one end of a tape measure against the inside edge of one rear brake backing plate and just measure over to the other side in this same spot. The early housing will be 55.5" long. The later one will be 57" long.

3/4" per side can make a big difference. Wheels are not cheap. I wouldn't use the sizes from just 'any stepside' as all these trucks are different.

I can tell you I had 20x9 with 4.75" backspacing on a 68 stepside with the narrow housing and it was pretty close to perfect. 255/45/20 tire. 5/7 drop. I just like a little more sidewall. It was very tight on the outer lip though.. AND I have the early housing.

Just figure out which one you have and we'll go from there. I'll help you all I can. 55.5 or 57. I'm betting it's the later one. Most if not original 5 lug housings are 57" long. Ive never seen an original 55.5" 'er with 5 lug but they may be out there.

Just for reference, the axles in the 57" housing are 31 5/16" long per side. 55.5 they are 30.5" long.

It's critical you know this before you get your wheels, especially if they're one off / billets, etc.

[cruisinthe34]

CC69RAT
Thanks, I'll be measuring for certain...... I just got the truck home at lunch and looking at the data plate....... looks like a very basic TRUCK !

A quick look up underneath revealed the EXPECTED trailing arms and what APPEARS to be a single leaf spring. no leaf pack, just a single spring.

[67ChevyRedneck]

Does it look like this:



That would be a factory "overload" spring.

[Ekliptix]

How does a person get 5" static drop in the front? The most I've heard of are 2.5" spindles and 2" springs. For the rear, I'm assuming a 6" spring and 1" spacer.

[CC69Rat]

http://www.thesuspensionsource.com/7...-drop-spindle/

[cruisinthe34]

67ChevyRedneck and CC69Rat. That's exactly what I have is the overload spring. The reason I asked was that in talking to CPP their question about the rear was does it have Leaf Springs, so NO It doesn't. They seemed to indicate there is some different methodology to drop the rear end with leaf springs.

[CC69Rat]

I'd pull the overload springs off and just make some body work tools out of them. Leaf springs make good slapping spoons.

Yeah, you have a trailing arm setup for sure.

One thing you might want to consider is a 4" spring and a 2" block (6") or 5" if you prefer. Keep all the spring you can. For example a 5" spring and 2 " block will ride better than a 6" spring and 1" block. A coil spring is nothing more than a straight metal bar all coiled up to create spring tension. Think of it like a diving board.

250 lb dude jumps off the end of a 12' long diving board. Boing.. and there's a certain amount of flex in the board. That's spring tension. Now cut 3ft off the board. .. would there be more flex or less? The shorter board will be much tighter, and flex less than the longer one. In this example I guess you can see why keeping more spring will ride better. 5" spring, 2" block vs 6" spring, 1" block. You still get 7" net drop. Make sense?

[Rod Run]

Originally Posted by Ekliptix

How does a person get 5" static drop in the front? The most I've heard of are 2.5" spindles and 2" springs. For the rear, I'm assuming a 6" spring and 1" spacer.

2+2.5=4.5

I used a 3" spring and 2" spindle for mine

[Ekliptix]

Dang, I wish I'd know Belltech had a 3" drop spindle before I did my ECE order and install.
Rod Run, who makes a 3" front spring, or did you cut one? Sorry for the thread hijack.

[funkfords]

Heres my truck it has 2.5" drop spindles + 3" lowering springs in front. The back has 2" lowering blocks and 5" lowering springs. My rims are 20 inch,I can't remember my tire sizes, but I will check if you are interested. I also have 1 5/8" spacers on the rear axle. Mike

[jondancer]

Funkfords , nice truck !

[Mike C]

They are not talking about the overloads when talking about leafs, but a leaf spring truck with NO coils and trailing arms. Which is what mine is.

I have an ECE 4.5" 5 lug disc conversion in the front and a DJM flip on the rear axle housing. The flip netted a 7" drop. I used the little pucks on the frame and did not C-notch. The rear is the wider '71-'72 5 lug housing. This was required to cram as much tire as possible with the offset on the wheels I could find for what I wanted to spend.

17x8 front with 4.5" bs and 235 55 17 tires. Rear is 17x9 with 5" bs and 275 55 17. Fronts are 27" high and rear is 29. And that's the max width you can get without modifying the inner bedsides at least with a 7" drop.

[funkfords]

Originally Posted by jondancer

Funkfords , nice truck !

Thanks Mike

[Rod Run]

Originally Posted by Ekliptix

Dang, I wish I'd know Belltech had a 3" drop spindle before I did my ECE order and install.
Rod Run, who makes a 3" front spring, or did you cut one? Sorry for the thread hijack.

CCP makes them

[cruisinthe34]

See how easy....... In just a day or so on this board with the right question...... and POW !! all the right answers.

FUNKFORDS..... That is the stance I'm going for on this build, even down to the rims you're sporting. My '41 F#rd I run these:


For this Chevy I'd like to know where your rims came from and the tire size if it's not too much trouble.

I've not run what we used to call 'lowering blocks' for a couple of decades , but I do understand the whole premise of spring tension etc. My '34 Chevy sedan I worked a lot with Eaton spring back in the day to get my ride height worked out after adding the weight of a V8 to the sedan etc. Sounds like now vendors have caught up to the demands of our hobby with more ready made solutions.

Thanks for all the input.

[cruisinthe34]

Well just ordered my 4/6 Drop kit from ECE. Nice folks. I was expecting to have to do a front disc brake conversion, but am told the '71 came with Front discs. So I ordered their Power brake booster set up and that should take care of that !

[Rod Run]

Originally Posted by cruisinthe34

Well just ordered my 4/6 Drop kit from ECE. Nice folks. I was expecting to have to do a front disc brake conversion, but am told the '71 came with Front discs. So I ordered their Power brake booster set up and that should take care of that !

I'm confused. Do you not have the truck yet and are still ordering parts? How come you didn't know if your truck had discs?