Leaf Spring Suspension Question

[Thumperbird]

Getting an early start on winter repairs/upgrades, there was no fall in Minnesota this year, went from summer to rain to chilly, like Jay said in another thread just a day or two here and there left at best.

Anyways, drivers side rear was sagging a bit, got worse after thrashing it this summer, so just removed rear leafs to install new.  Noticed some pretty deep grooves carved into the top side of the housing tube where the U bolts contact,  less than a 1/16 but more than a 32nd I say.  This came from axle wrap and back and forth rotary motion I suppose.  Not sure how much is new versus from 50 year age but I know some is new as the 2 year old ubolts show wear as well.

All bushings and hardware are new, the u bolts were cranked very tight compressing the large isolation pads quite a bit so not sure how I would have stopped it from happening.  I did experience some wheel hop on certain surfaces.

First question is wondering how much of a groove is tolerable before I should worry about housing failure?
Second question is though I am hoping new springs reduce wrap i suspect it will be an on-going issue, I know traction bars are easy install but I do not care for the looks wondering what other options you guys can think of to reduce the wrap/motion?  Caltracs does not make anything for a tbird, do not want to get too crazy like 4 link or anything.

For reference springs are 5' long, a little over 2' in front of axle a little under 3' behind, 5 leafs a couple straps both front and back.

Thanks.

[67428GT500]

I had a question. Did you replace your U bolts? The factory Ford bolts are flat on the axle side of the Ubolt. Many aftermarket bolts are round.  I have seen them gall the housing. I used to see that happen a lot on cars with lowering blocks.
                                                                                -Keith

[thatdarncat]

Back in the days before Cal-Tracs were invented I used to run a pinion snubber on my car. It helped considerably on the axle wrap. I’m not sure what your car has now, there are a couple ways you can do it - see if you have a bracket on your rear end pumpkin now, and wether it has a bumper attached, and either extend down the bumper from the floor closer to the bracket on the pumpkin, or extend the bumper from the pumpkin closer to the floor. You might have to reinforce the floor in that spot if it isn’t already. On my car, it was missing the snubber plate attached to the 9”, Once I added that I found it was close enough to the floor bumper I didn’t need to extend it. Your car may sit low enough that is the case too. Leave some clearance for suspension movement. It’s one of those things you just have to experiment with. Sometimes you might have to lengthen the bracket on the pumpkin to line up better. Below I have a picture of an extended pinion snubber that places used to sell years ago, but can be easily fabricated, to give you an idea.

However, when the Cal-Trac bars become available and I added those it was a giant improvement in traction & consistency. Even if Calvert doesn’t have Cal-Trac bars for your car listed on the website you could try calling and ask if they have made any for customers, doesn’t hurt to ask. I have known a few people who have made their own copies, it’s a pretty basic design and mostly just requires welding skills.

[Thumperbird]

Yes, new round u bolts.  One would think the sawing would self terminate as surfaces widened, maybe I will flatten the underside of the bolts.  Top side isolater back half is also trashed already from lots of compressive and slip cycles I suppose.

No pinion snubber nor do I think a 65 thunderbird ever had one, will look into this and yes will reach out to Calvert or consider fabbing something.

Thanks all for feedback, don't like the idea of that rear moving around so much I like running it hard so hoping to make some changes here.

[Val406]

One reason the rear housing could squirm is because of the isolaters. Get rid of them. I did so this year with no ill effects and, as a bonus gained almost an inch of ride height.

[shady]

clamp the springs about a foot in front of and 16" behind the perch.

[wayne]

If you could move one shock so it has one on each side of the rear end like factory 4 speed cars it helps. This with the clamps and snubber like others have said should be all you need. Mopar used to sell a adj snubber that worked well just weld it on your plate i dont know if direct connection still has them.

[machoneman]

Moroso and other chassis parts suppliers sell adjustable pinion snubbers:

https://www.moroso.com/c-e-shop-browse/97000/--9729/

I'm still a fan as long ago we ran Lakewood  bolt-on traction bars with a similar snubber on a BBC '69 Camaro (sorry!) that had great bite (1' wheelies) and 10.90 e.t.'s in a 3,550 lb. ready-to-run car.

Today, I'd run the Calverts but heck, no issues at all with a properly set-up leaf car, traction bars and a well-set snubber.  And as Val said above, those isolaters need to go!

[GerryP]

...we ran Lakewood  bolt-on traction bars with a similar snubber on a BBC '69 Camaro (sorry!) that had great bite (1' wheelies) and 10.90 e.t.'s in a 3,550 lb. ready-to-run car.

Today, I'd run the Calverts but heck, no issues at all with a properly set-up leaf car, traction bars and a well-set snubber.  And as Val said above, those isolaters need to go!

Those who were not around "back in the day" would be shocked...shocked I tell you!...to discover that the early Pro Stock cars ran slapper bars on leaf springs.  No four-links, coil overs or anything else fancy.  The photos are out there.  Of course, the bars were good for only one weekend as they would invariably bend.  I run slapper bars on the Fairlane.  They work.  I understand the OP's interest in not running them.

[e philpott]

Maybe South Side Machine Lift Bars would have something for the Bird ? Lakewood Traction Bars painted Flat Black ?

[shady]

The Grump took the credit for inventing slapper bars. He also had some really long ones he would put a caster on the back end of em and had instant wheelie bars. Always the innovator.

[Thumperbird]

Thanks for all of the ideas.  Chatting with Caltrac but suspect it will be a no go once they see the somewhat unique front hanger we have to work with.  Would like to change isolaters to urethane but they do not exist, removing isolaters presents other spring clamping problems, was hoping not to have to make custom plates, etc., but maybe.

[67428GT500]

AMK has the correct U bolts flattened and with a waffle pattern.  The reason I asked about the bolts is because I had an issue until I returned to the flat bolts. They no longer walk under load.

                                                                                                      -Keith

[chris401]

Eaton is expensive but you get what you pay for. I have installed them on customers trucks. I have yet to redo my own six springs for $2400. Here is a 65 Thunderbird. They had the correct U bolts for my truck.

https://www.eatondetroitspring.com/db/es-partsinquiry2.php?syear=1965&smake=Ford&smodel=Thunderbird&sbody=2%20DR%20Convertible&seng=V8%206.4L%20-%20390cid

[Thumperbird]

Thanks for the leads, Caltrac is out unless I change the hangers.
Thinking of new/correct u bolts, extra spring clamps, more rigid or delete isolators, maybe a pinion snubber.
Trying to remind myself I never built it to thrash too much but the power is fun.
Need to keep my foot out of it more so I don't break stuff I guess. 

Thanks.