Bump stop without clearance - cause of squeaking?

[JozefJ]

I just saw that the bump stops on my LCA's do not have any clearance. See the picture. Could this be a reason why my car is squeaking/groaning when ging over uneven roads and speed bumps?

And could this be fixed by adjusting the torsion bars, turning the adjuster bolt clockwise until I reach a 1-1,5" gap? And do you think the adjuster has enough room to move? See the second pic.

Pretty new to the classics scene, I'm trying to learn. Thanks for thinking along!

 

[72bluNblu]

Yes, that could definitely be the reason for the squeaking and groaning noises. Your suspension is pretty much entirely that bump stop at this point

Yes, you should raise the suspension using the torsion bar adjusting bolt, if you can. I doubt you have enough adjuster left to get 1” of clearance.

It looks like your adjusters are already most of the way in, so, you probably won’t be able to get the car where it actually needs to be. That’s a symptom of worn out torsion bars. Just like any spring, torsion bars sag over time. They just do it radially, so the car lowers itself.

Based on your pictures, it looks like it’s time to rebuild the suspension with new torsion bars, bushings, and probably even shocks if you intend to drive the car much. Personally I would increase the size of the torsion bars as well, but given that I don’t know what your plans for the car are I’ll leave that alone for now.

If you do raise the car with the adjusters, you’ll need a new alignment as well. This is the method for setting the factory ride height, it’s in the factory service manual. “V&L” is the carline for an A-body.

And if you’re running radial tires and not bias ply tires ignore the factory alignment specs and use these

 

[Murray]

A little grease?

 

[72bluNblu]

A little grease?

Bit late for that I think!

 

[JozefJ]

Yes, that could definitely be the reason for the squeaking and groaning noises. Your suspension is pretty much entirely that bump stop at this point

Yes, you should raise the suspension using the torsion bar adjusting bolt, if you can. I doubt you have enough adjuster left to get 1” of clearance.

It looks like your adjusters are already most of the way in, so, you probably won’t be able to get the car where it actually needs to be. That’s a symptom of worn out torsion bars. Just like any spring, torsion bars sag over time. They just do it radially, so the car lowers itself.

Based on your pictures, it looks like it’s time to rebuild the suspension with new torsion bars, bushings, and probably even shocks if you intend to drive the car much. Personally I would increase the size of the torsion bars as well, but given that I don’t know what your plans for the car are I’ll leave that alone for now.

If you do raise the car with the adjusters, you’ll need a new alignment as well. This is the method for setting the factory ride height, it’s in the factory service manual. “V&L” is the carline for an A-body.

View attachment 1716382138

And if you’re running radial tires and not bias ply tires ignore the factory alignment specs and use these

View attachment 1716382139

Thanks a lot! I'm going to try and give the adjuster a few (half) turns to see how far I can go. I had already planned to put in new shocks next monday. And new lower ball joints later that week. So the plans are there.

I'm looking to use the car mostly for cruising/street. What size torsion bar would you recommend for a '73 Dart Sport?

By bushings, do you mean all bushings, or just the LCA bushings? The UCA is a lot newer than the rest of the suspension.

 

[72bluNblu]

Thanks a lot! I'm going to try and give the adjuster a few (half) turns to see how far I can go. I had already planned to put in new shocks next monday. And new lower ball joints later that week. So the plans are there.

I'm looking to use the car mostly for cruising/street. What size torsion bar would you recommend for a '73 Dart Sport?

By bushings, do you mean all bushings, or just the LCA bushings? The UCA is a lot newer than the rest of the suspension.

Make sure you take the weight off the suspension before you turn the adjusters any, and it would probably help to use some WD-40 or penetrating oil on them before you turn them any.

These cars were dramatically undersprung from the factory to begin with. Personally, I wouldn't use anything less than a 1" diameter torsion bar on any A-body. PST sells a 1.03" bar that's pretty popular, I don't know about getting parts to the Netherlands. @BergmanAutoCraft also sells some 1.08's (as well as all kinds of suspension goodies for better handling) although that's getting into handling car territory. The factory rates were sub 100 lb/in, most modern cars are in the 200+ lb/in range. A 1.03" is around 215 lb/in, so quite a bit more than factory (which was VERY low) but still less than a modern sports car. Basically commuter car rates. My '74 Duster (demon clone) is a daily driver set up for autoX and I run 1.12" bars with a 300 lb/in rate.

Keep in mind too that your current ride quality is much stiffer than factory, because you're on the bump stops all the time. A 1.03" bar would likely result in a softer ride than what you've got now.

If the UCA's are newer they may be ok. If the LCA bushings haven't been changed recently, or you don't know their history, I would replace those now especially if you're doing the torsion bars and lower ball joints, because you'll have everything apart to replace the LCA bushings. If they look like the rest of the suspension in that picture then they're likely toast.

 

[JozefJ]

Make sure you take the weight off the suspension before you turn the adjusters any, and it would probably help to use some WD-40 or penetrating oil on them before you turn them any.

These cars were dramatically undersprung from the factory to begin with. Personally, I wouldn't use anything less than a 1" diameter torsion bar on any A-body. PST sells a 1.03" bar that's pretty popular, I don't know about getting parts to the Netherlands. @BergmanAutoCraft also sells some 1.08's (as well as all kinds of suspension goodies for better handling) although that's getting into handling car territory. The factory rates were sub 100 lb/in, most modern cars are in the 200+ lb/in range. A 1.03" is around 215 lb/in, so quite a bit more than factory (which was VERY low) but still less than a modern sports car. Basically commuter car rates. My '74 Duster (demon clone) is a daily driver set up for autoX and I run 1.12" bars with a 300 lb/in rate.

Keep in mind too that your current ride quality is much stiffer than factory, because you're on the bump stops all the time. A 1.03" bar would likely result in a softer ride than what you've got now.

If the UCA's are newer they may be ok. If the LCA bushings haven't been changed recently, or you don't know their history, I would replace those now especially if you're doing the torsion bars and lower ball joints, because you'll have everything apart to replace the LCA bushings. If they look like the rest of the suspension in that picture then they're likely toast.

This helps a lot, thanks. All the work seems doable. Just not looking forward to replacing the LCA bushings; from what I'm seeing on YT that's quite the pita..

 

[72bluNblu]

This helps a lot, thanks. All the work seems doable. Just not looking forward to replacing the LCA bushings; from what I'm seeing on YT that's quite the pita..

The easiest way to do it is with an 1 3/8 tap, you just thread the tap into the outer bushing shell and then press the tap and the shell out of the LCA. It's MUCH easier than welding a washer on there or even just splitting the shell with a cold chisel and if you support the LCA well there's pretty much no chance of damaging the LCA.

The taps can be had used on eBay for in the $20 range usually, well worth it do save the hassle even if you're not planning on doing it more than once.