Clunk from front when first stopping after changing direction

[50Splitman]

My 1950 standard has a clunking sound from the front end and I can't figure out the root cause.

The beam is original, early-style July 1950 number with the seam-welded shock towers. Cable brakes are NOS (cables, shoes, springs, etc.). Link and king pins were replaced using the proper tooling/reamer and shimmed and adjusted to factory spec. Torsion springs were replaced with the correct number of leaves for a July 1950 build date from another Beetle (original were in pieces). Control arms are within factory spec, and control arm bushings were replaced. Old grease was removed from the front beam and replaced. Front wheel bearings have been replaced and wheels are adjusted properly. Tie rod ends have no play. Steering box was rebuilt and is adjusted properly. Shocks are NOS. Control arm bump stops are NOS. Front end is aligned, tracks straight, and stops straight. When the car is on jack stands, I cannot find play in any of the suspension components.

The clunking sound from the front end occurs a a split second before I come to a stop for the first time going either direction, e.g., I am pulling out of my garage in reverse, and the first time I apply the brakes I hear the clunk just before I come to a stop. It only happens once, until I go forward, and then the first time I come to a stop when moving forward, it happens, but doesn't happen again while I'm out driving. I've removed the spare and there is nothing in the trunk rolling around that could make this sound.

Any ideas would be greatly appreciated. This issue iis driving me crazy since it only happens once every time I come to a first stop after changing directions. I'm concerned about this being a safety issue, but all the usual wear items have been replaced and adjusted. The only thing I can think of at this point is maybe one of the torsion springs may have broken? I have never experienced that issue before, so I don't know what it feels like. I never drove the car with the old broken torsion springs.

[busdaddy]

I'd conscript two helpers to stand at each end of the car and push it back and forth while a third sits inside with thier foot on the brake, you can put the wheels on one side on the curb and lay in the gutter under the car as you listen for the source of the clunk. You may not find the exact source, but at least you can narrow the search area down, a length of tubing held to your ear also helps pinpoint noise sources sometimes.
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

Слава Україні!

[Fly-wheel]

only a suggestion ...
The clunk I get when turning the steering wheel turned out to the link pins being undersized ( both sides x4 of had been machined down in diameter by approx 1mm. This meant the torsion arm forging couldn't clamp equally to the pinch bolt so the pins would move. I still have not solved it as the pinch bolts had too long a thread on them but have ordered new bolts with a longer plain shank.
Try jacking the car up and holding the wheel top and bottom see if there is any excessive play?

[50Splitman]

Thanks for the suggestions, busdaddy and Fly-wheel.

I'll gather family and friends and get everyone to help push so I can take a listen to try and locate the sound from outside the car.

I've grabbed the wheel top/bottom and also side/side and have found no play in either direction. Interesting issue you are experiencing, though....I didn't think that was possible. FWIW, I replaced the link pins and bushings, as well as the king pins and bushings, all with NOS parts. I don't remember having any issues with the pinch bolts not clamping properly when tightening them, but I'll double check for this specific issue.

[VW_Jimbo]

So. Something is changing after sitting over night? Then you go for the first drive of the day and hear this, once?

Or is it multiple times a day. Like after shutting the engine off? Or some set amount of time? Or after parking up hill? What are those other variables?

It sounds like something gets stretched, then remains stretched, then after going into non use, returns to a primary relaxed state. Sound correct? Or is there more to it than that?
_________________
Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[wagen19]

[Tvättbjörn]

[VW_Jimbo]

[wagen19]

[50Splitman]

[50Splitman]

[wagen19]

[wagen19]

[Käfer2]

Supporting wagen19 in his philosophy of never posting pics

"part nr. 16, "splint pin", or "cotter pin" N 12 540 (1952 parts book)":

[wagen19]

[50Splitman]

I want to start off with a huge Thank You to Käfer2 and wagen19! Your feedback and insight has been hugely helpful.

Let me try and address some of both of your questions and comments:

- Yes, those are pictures of my actual 50 standard Beetle front/rear brake assemblies from 2023 when I was rebuilding the chassis . First time anything on this car was touched since 1978 when it was parked by the previous owner. I’m actually excited to share the pics and openly welcome all feedback, as after 30+ years of working on VWs, this is my first ever standard brake beetle, so rebuilding these was a learning experience.

- Rims were professionally painted with single stage PPG acrylic urethane paint. Drums are epoxy coated (outsides only) with Eastwood chassis black epoxy paint. Lugs have been checked several times and they are to factory torque spec.

- Great catch on the cotter pins being missing in the pics! I do remember removing the old ones and I had to purchase new ones that were the correct diameter/length to match the original ones. What I don’t remember is if I installed them after this pic was taken. I’ll need to definitely check - this is something that I could have completely missed, and could be the root cause.

- I have not heard about the paint effect on shoes before, but I certainly see your point. I’ll check the shoes and rivets for tightness.

- The build date of my split is July 13th, 1950. The front drums are stamped 6/1950, and the front beam number corresponds to July 1950.

- The front axle spacers are what was on the car when I bought it 25 years ago. You are correct, there is a small dent on the spacer, and from what I could tell, it didn’t seem to leave any marks/impact on the original wheel bearings which looked actually very nice, although I did replace all 4 front wheel bearings with NOS.

- I do happen to own a set of NOS ‘grooved’ front axle bearing spacers. I could swap out the early style ones for my grooved NOS ones. I had no idea about the spacer changes over the years, and I’ll have to measure the diameter to see which ones are installed. Given the date of the front beam, I assume they are original to the car, but I’ll of course measure them

I won’t be able pull things apart until later next week when I’m where I store the car. When I do, I’ll update this thread with new pics and my findings on everything. Thank you all again! Been on the samba over 20 years and I love the passion we all share for these cars, and willingness to help each other!

[50Splitman]

Problem solved!!

After a very long delay due to other priorities, I finally had time to take everything apart, I found the following:

- The cotter pins were present in the brake adjusters on all 4 wheels, so that wasn’t the issue. Apologies that the pictures were taken earlier than the final assembly, and were misleading to a possible root cause.

- The wheel bearing spacer on the front axle studs measured 40mm in diameter. There was no evidence of grease leaking past the seals, and the seals were in good shape. I left these in place.

- I found no evidence of loose brake lining on the shoes, so I took no action there.

- I DID find that the three bolts on the right-side front backing plate that secure it to the steering knuckle were loose about a turn and a half. The left side were tight, so I tightened theright-side backing plate bolts, reassembled everything, and no more noise!! Thank you wagen19, you indeed were correct with your assessment.

Thanks agains to everyone who provided insight and guidance, and I’m happy to have solved the noise and back to enjoying driving my 1950 a few times a week!