Hot Rods Chevy 3100 Straight Axle upgrade options?

Hi Guys,
I'm trying to figure out what I can do to improve the ride on my '51 Chevy 3100 WITHOUT IFS CONVERSION. I know I've seen 4 link options for old 20s-30s roadsters, but can't seem to find anything about anyone upgrading the I beam on a truck like mine. I have mono-leafs on it right now, but do still own the original spring packs. Any ideas on what I can do to get the best ride out of the straight axle setup? I know that the stock axle came with positive camber for riding on bias plys. I have looked at getting the axle curved to give a bit of negative camber since I am running radials, but have had a difficult time finding anyone with the equipment to do it on anything smaller than a big rig. I am not interested in, and more particularly I cannot afford to do a Mustang II upgrade. Please save your effort and do not post about how I need to go that route. I prefer the traditional setup.

 

The ride relates mostly to spring rate, the handling relates mostly to alignment, eh?

What exactly is it about the ride that you don't like, now?

 

It's stiff and bumpy. Also I do get some bumpsteer. Mainly looking to soften the ride though.

 

Also, if it helps, the steering box is spaced to the left of its original position by about 1" in order to clear the V8

 

Getting a soft ride usually requires softer springs with more travel, which is hard to do if you want to have it sit low.

 

Regarding your axle, check with the guys who drop them, they may be able to change it to your liking,

 

Most large metro areas have truck service shops capable of aligning a big rig beam axle, by bending it. They should have no trouble aligning yours to a custom spec.

Softer springs, and some really good shocks will indeed help, to an extent. You want a soft spring, to respond to the bump, and a stiff shock to reign in the suspension movement.

As Jim mentioned, lowering and travel don't go together well. Getting the axle dropped keeps the suspension bits in the same location, while moving the spindles up. It does, however, mess with the steering geometry on this model.

 

I would look into new shocks, a tire with more sidewall and a stock front wheel width. I can only guess because you don't mention anything about these items.

 

I would give Nostalgia Sid a call in the new year. He can give you the straight dope on how to get your rig fixed up, lowering and steering wise: http://www.droppedaxles.com/CHEVY_AXLES.html

 

They are 215/70R15

 

None of the truck shops want to touch my old truck. I've called around quite a bit trying to hunt down a place to do it... and I live in Houston where you'd think there would be a ton of options. It's been quite frustrating. I only found one shop that said they had the equipment to do it on a regular sized car, but said they hadn't fired it up in over a decade and weren't even sure it would work anymore. Also, the only guy still working there with any experience doing it was out on an extended leave for health issues. Thinking maybe a dropped axle is a good idea.

 

Actually I think you are going at it backwards.
Put a hardtail on that motorcycle, you will love the ride of your 3100. Simple.

 

Here's what I would do:

1. Rebuild the stock springs, smoothing and rounding the ends, cleaning and painting all, and installing Teflon strips. Remove the longest main leaf, and the leaf two shorter than that.
2. Get a dropped axle from Sid, and have him bend up your steering arms to accommodate the drop, and align it during the drop.
3. Measure the compressed and extended length of the shocks. Cross reference that in the Monroe catalog that can be found on the HAMB. Find out what vehicles take a shock in that configuration. Find a Bilstein, KYB Excel-G or Gas-A-Just shock in that configuration.
4. Ask the shop with the old equipment if they want to sell it, cheap.

 

Haha on #4
Thank you for such a comprehensive answer. I appreciate it!

 

there is an old shop in town that has the axle bending stuff, but they also don't have anyone who will use it (the guys who used to use it, passed away in the past 10 years). I expect I could buy it if I tried hard.... this shop has been around for 60 years.

Looks like you're getting some good ideas, so far.

 

Haha. I just want all the ride quality, handling and control that I can affordably manage to go with the 400+ HP I have in the truck. I've ridden narrow tired hardtails. They are cool as hell, but my back is long past handling that kind of stuff any more.

 

The stock springs have a bunch of leaves, so you can tinker with spring rate. The Teflon strips remove internal resistance, and allow the metal spring to do its job, as a spring, rather than a friction shock absorber. It can take a little time to tune a leaf spring, but the cost is pretty low.

You want your springs supple. You need them to move, in order to accommodate bumps. For a good, comfortable ride, you want them not quite soft enough to allow excessive body roll, and bottoming out, while still holding up the vehicle. Good stiff shock absorbers keep the movement under control.

If you are still at a good ride height, like the ride, but are getting into body roll, an anti sway bar will fix that right up.

 

Thank you. I did forget to mention that I do have a sway bar. It is pretty solid through the turns, just bumpy. I'm always afraid of hitting a bump at speed in freeway traffic and having it get squirrely on me. I think I will start playing with the old leaf springs. Think I should worry with getting them re-arched?

 

Re-arching will raise the truck.

I would seek out some good shock absorbers. They are always a good idea. This thing has a whole lot of heavy metal hanging off of the springs to keep under control, and a big old frame and body to keep stable.

 

Very few people here would recommend the MII route.

 

Yup. I would go the Dakota route, from El Polacko over at Industrial Chassis.

A vastly superior setup, from a real engineer, and a super-cool dude.

 

Stock springs with the leaves removed end up lookin like this, They not only look like crap, they ride like crap and they steer like crap. That is my front spring under my truck just as the truck on it at Bonneville in my avatar. Trouble with old leaf spring rigs is guys climb out of cushy riding late models and then complain because the leaf spring rigs don't have a cushy ride. You can get the multi leaf springs to ride reasonably smooth by doing the clean up and teflon strips that was suggested earlier but it probably won't be near as low. Too many guys tend to go overboard on shock rate because of the rig being a truck, you want enough shock to smooth out the ride but not real stiff shocks.
Bump steer is usually because the drag link isn't as level as it should be if the truck is lowered. I've got that on mine too.

With the jack out from under it there is about 1-1/2 inch clearance. between the axle bumper and the frame.

 

That depends on how bad off the stock springs are.

 

so you want an old truck suspension to not ride and handle like an old truck suspension
(not trying to be a smart ass)
a better quality spring
a better shock
add a sway bar
I would recommend a Sids Axle if ya want it lower
he can help you improve the steering as well
good luck

 

I tried the mono-leafs too, rode like a lumber wagon! So, I went with a 3" axle from Sid, and rebuilt the stock spring packs using only 5 leafs, with Teflon liners. To eliminate bump-steer AND get the steering wheel out of my face, I made a new steering box mount out of 1/4" plate which moved the steering box forward 2" and raised it about 2". I still had a little bump-steer so I modified the Pitman arm by cutting a 1" section out. The idea, as stated above, is to get the drag link level. So, with this setup, the truck sits pretty low, rides as good as any MII set-up I've ever had, and has zero bump steer. I also run a steering damper that you can get from NAPA.

 

^^^^^This. Do this.^^^^^ This is how you do it.

 

I have a 49 gmc. Looking to do the chassis this summer. I have a m2 set up but just love the simplicity and coolness of the straight axle. I want to keep the straight 6. So I am really thinking on keeping the stock axle Thanks for posting this

 

Very nice setup. Are you running a V8? If so, did the steering box move add a lot of clearence for the exhaust?

 

^^^ Thanks. I'm running a 235 but the box could be offset an inch or so for a little more clearance if needed.

 

Where in Houston are you. Im not understanding why no shop in Houston would even want to touch the truck. Im on the west side in brookshire. I can ask if a shop in Hempstead would maybe look at it. I run an beam axle in my 58 chevy(all done in California though). Do you have a drop axle in it now or is it still stock height. You can change your caster with shims(how ive done it on my truck per instructions of a spring shop). I run an axle above spring setup and run 8 degree caster with the axle leaning back. I can run it straight down the road no problems. Feel free to send me a message if you got any questions. Ill be glad to answer them.