Thread: Mono leaf front springs .. Good or Bad?

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I have a friend who works for a large spring manufacturer here in my city.

We got to discusing MONO LEAF transverse springs and he cautions AGAINST using them. His shop has replaced several of them.

He feels a MULTI LEAF spring can hold together if the main leaf breaks.

He admits they ride softer, BUT if it breaks it could cause sever damage. I currently have one under my '28 A Tudor Hiboy - flathead powered.

Anyone here have one of them break??

Hi Dave,

I haven't heard of one breaking, but they do sag.

I pulled the Posie's Super Slider from my 32 perhaps eight years ago.
Nothing was wrong with it and it was working ok.

Installed a Durant Mono-Leaf in an effort to gain some front end travel.
(I should have notched the frame - you can bet the 31's frame is notched.)
The travel was gained, but now that it's sagged it's about to where the Posie's was.

I did add a 3/8" shim - in addition to all of the shims that Durant supplied - much more and part of the shim pack would be out of the crossmember.

Not sure what's next.

I'm thinking of adding a couple of short leafs to the Durant in an effort to get it back up to where it was originally.

If the Posie's spring would not have been on the shelf, I would have bought one anyway.
Looks like it's gonna work well with the notched front end.

Originally posted by C9x
Hi Dave,

Mornin' Jay; getting settled in?

I haven't heard of one breaking, but they do sag.

I pulled the Posie's Super Slider from my 32 perhaps eight years ago.
Nothing was wrong with it and it was working ok.

Installed a Durant Mono-Leaf in an effort to gain some front end travel.
(I should have notched the frame - you can bet the 31's frame is notched.)
The travel was gained, but now that it's sagged it's about to where the Posie's was.

I did add a 3/8" shim - in addition to all of the shims that Durant supplied - much more and part of the shim pack would be out of the crossmember.

Mines a Durant as well. I started with the main leaf half way between the shims. (have about 3" between the top of the axle - 4" Bell Tube - to the underside of the spring pack, but no frame notches) I ALSO have a Posie's spring - with the slider buttons - that was originally installed.

Mulling this situation over; I wonder if I took the # 2 leaf from the Posie's, remove one of the Durant shims and put the Posie's # 2 leaf ABOVE the Durant main leaf; if this would stiffen the ride too much?

Settled in ok.
Shop is up and running.

Just need to get ahead of the weeds in the back.
Geez, poison and weedwhacking don't see to cut it.
Every time I turn my back....


Anyway, by #2 leaf I'm guessing you're talking about the longest non-eyed leaf.

It may give just the right amount of help since the spring 'pack' doesn't have the progressive support a full leaf spring would.
I don't think it would hurt the ride at all.

My thinking was the opposite.
I was going to try to find 2-3 of the (different length) short leafs and add those in place of the shims.

Once the 31 is up and running I may tear the 32 apart and notch the frame on it.

Fwiw - a piece of 1 x 2" x .120 wall rectangular tubing makes a nice filler.
Cut one of the long sides off leaving the 1" sides as long as you can.
You'll end up with a just under 1" notch this way.

I took AV8's advice and tilted it slightly so the spring hits the full width of it instead of hitting only on the corner.
I think that's gonna work quite well.

Another fwiw on square and rectangular tubing - I cut one side off many times so as to make body mounts, engine mounts etc.
After the cutting and clean-up grinding I end up with a nice piece of short 'channel' that looks good due to the curved edges.

Cutting the narrow side of a rectangular piece gives you a good start on a shock/headlight mount combo for a highboy.

As far as raw stock goes, just specify the wall thickness you want depending on what you're doing.
3/16" for motor mounts, 1/8" for body mounts etc.

Originally posted by C9x
Settled in ok.
Shop is up and running.

Just need to get ahead of the weeds in the back.
Geez, poison and weedwhacking don't see to cut it.
Every time I turn my back....

I thought all AZ properties were paved !

I wish you were located closer .. sure could use your machine shop talents! (and lathe!)

Anyway, by #2 leaf I'm guessing you're talking about the longest non-eyed leaf.

It may give just the right amount of help since the spring 'pack' doesn't have the progressive support a full leaf spring would.
I don't think it would hurt the ride at all.

My thinking was the opposite.
I was going to try to find 2-3 of the (different length) short leafs and add those in place of the shims.

Right on the # 2 leaf. But now you have me thinking about a couple of the shorter leafs.

At the moment, with the front end loaded - with engine and trans - I still have a couple of inches at the frame rails.

Once the 31 is up and running I may tear the 32 apart and notch the frame on it.

Fwiw - a piece of 1 x 2" x .120 wall rectangular tubing makes a nice filler.
Cut one of the long sides off leaving the 1" sides as long as you can.
You'll end up with a just under 1" notch this way.

I took AV8's advice and tilted it slightly so the spring hits the full width of it instead of hitting only on the corner.
I think that's gonna work quite well.

Another fwiw on square and rectangular tubing - I cut one side off many times so as to make body mounts, engine mounts etc.
After the cutting and clean-up grinding I end up with a nice piece of short 'channel' that looks good due to the curved edges.

Cutting the narrow side of a rectangular piece gives you a good start on a shock/headlight mount combo for a highboy.

As far as raw stock goes, just specify the wall thickness you want depending on what you're doing.
3/16" for motor mounts, 1/8" for body mounts etc.

Like you, I have been using various pieces of square and rectangular for gussets and brackets. There is a place here in town - called the Metal Supermarket - owned by a lady that lets me scrounge through the "off cuts" bin for all kinds tube. (it's kinda like being in a candy store!! ) I take her a box of donuts once and a while and she usually just gives me the pieces!

Will retrieve the Posie's spring tomorrow - from upstairs - and report back.
Thanks for the ideas!
Dave

Originally Posted by Digger_Dave

I have a friend who works for a large spring manufacturer here in my city.

We got to discusing MONO LEAF transverse springs and he cautions AGAINST using them. His shop has replaced several of them.

He feels a MULTI LEAF spring can hold together if the main leaf breaks.

He admits they ride softer, BUT if it breaks it could cause sever damage. I currently have one under my '28 A Tudor Hiboy - flathead powered.

Anyone here have one of them break??

Just last 4th of july coming home from a parade in my 32 highboy coupe I hit a large bump in the pavement @ 45 mph and the mono leaf spring on the front snapped in half about 8 inches from the end eyelet bracket. It immediately put me in a left 180 with the tires squaling and over I went on the passenger side and down a grassy hill. Took about 3 months to repair my ride and now have installed a posies multi leaf super slide spring. Love it and really improved my ride not to mention peace of mind.