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Lotus Europa Forums => Garage => Topic started by: HoraceM22 on Wednesday,September 11, 2024, 12:10:45 AM

Title: What's this clonk?
Post by: HoraceM22 on Wednesday,September 11, 2024, 12:10:45 AM
As I slowly reverse my UK '74 TCS off my downward sloping drive with a bit of rh down lock on there is a slight clonk from what I think is the rh rear of the car, but not too sure. I'm in the process of checking all the bolts on the undersidefrom back to front.  (They're all "new" as the car has been TOTALLY restored) So far everything has been tight as expected and the two long suspension arms where I thought the issue might be are all fine. I also think I may have heard the odd clunk whilst driving.
Any ideas?
Title: Re: What's this clock?
Post by: gideon on Wednesday,September 11, 2024, 07:23:13 AM
Is there any play between the driveshaft U joints and the driveshafts?  George Karellas did a nice explainer on his youtube channel about driveshaft U joints.  I didn't know this before, but apparently the retaining clips come in different thicknesses and if you get the wrong ones then you can get a clonk.  Here's the relevant bit

https://youtu.be/t45cp1hY2C4?t=710
Title: Re: What's this clock?
Post by: 4129R on Wednesday,September 11, 2024, 07:52:54 AM

You, as the author of this thread, can edit the title from "clock" to "clonk".
Title: Re: What's this clock?
Post by: 314159td on Wednesday,September 11, 2024, 08:57:32 PM
Make sure to empty out the trunks before you start tearing things apart.
Many suspension clunks can be found by strategically jacking under the control arms/uprights and giving the wheels a yank through every axis. If you let everything go to full droop, that isn't representative of driving conditions.

For a recent restoration, readjusting the front hub tapered wheel bearings comes to mind. They're difficult to set correctly with that silly felt ring in the way.
Title: Re: What's this clock?
Post by: GavinT on Wednesday,September 11, 2024, 10:05:49 PM
Apart from the items mentioned, the first thing I'd be checking is the rear stub axle nuts.
Title: Re: What's this clonk?
Post by: HoraceM22 on Wednesday,September 11, 2024, 11:08:54 PM
Ahh, sorry about the "clock instead of clonk" bit.

Anyway thanks for the suggestions. I hadn't thought that it could be the driveshafts as they, along with everything else, has been either reconditioned or replaced, but after ensuring every nut and bolt from the front engine pulley backwards is tight, I was thinking that they were all that's left to consider. A couple of engine mounts were just tight but not TIGHT, but that was down to me anyway.

I have jacked under the rear uprights and given the wheels a "top-to-bottom and front-to-back" tug, MOT style, without success, but not in the in-and-out direction, so that will be my job for today.
Thanks guys.
Title: Re: What's this clonk?
Post by: Dilkris on Thursday,September 12, 2024, 08:26:45 AM
As I slowly reverse my UK '74 TCS off my downward sloping drive with a bit of rh down lock on there is a slight clonk from what I think is the rh rear of the car, but not too sure.
Any ideas?

Can you identify whether it is caused by reversing or the rh lock? ie: if you reverse without lock, any noise?
Also are you free wheeling down your sloping drive or driving under power ?
You need to positively identify what promotes the noise so as we can (hopefully) identify the cause. 
Title: Re: What's this clonk?
Post by: BDA on Thursday,September 12, 2024, 08:35:15 AM
It appears not to be your problem but stub axles are always worth checking out. I rebuilt my car using the original 10,000 miles old stub axles and after probably another 15,000 miles my driver's side stub axle was toast (see picture). The nut was tight, I didn't track or otherwise abuse overly stress my car. It's unusual but stuff sometimes happens and those stub axles are a huge weak point. They aren't even hardened!
Title: Re: What's this clonk?
Post by: HoraceM22 on Sunday,September 15, 2024, 10:47:36 PM
Dilkris, I'm about to get my nephew over to be able to find (if poss) where the noise actually is emanating from. As we all know, a noise can seem to be come from "A", but it actually from "B".

Anyway with two of us we can look into the engine bay and as one twists, turns, pulls and pushed the other can actually see if there is any corresponding noise from within.

Similarly, when I gentry reverse down my drive he can be closely looking at the wheel /engine bay etc. although I suppose this won't make the noise on command eh?
Title: Re: What's this clonk?
Post by: 4129R on Sunday,September 15, 2024, 11:51:49 PM
I had a mysterious sound which I thought was from a front wheel/brake disc, it was road speed related, and it turned out to be a new speedo cable that I had just put in.

Sometimes the noise can come from unusual places.
Title: Re: What's this clonk?
Post by: Dilkris on Monday,September 30, 2024, 06:40:43 AM
Dilkris, I'm about to get my nephew over to be able to find (if poss) where the noise actually is emanating from. As we all know, a noise can seem to be come from "A", but it actually from "B".

Anyway with two of us we can look into the engine bay and as one twists, turns, pulls and pushed the other can actually see if there is any corresponding noise from within.

Similarly, when I gentry reverse down my drive he can be closely looking at the wheel /engine bay etc. although I suppose this won't make the noise on command eh?

Any progress with this? I'm curious to know what was the source of the noise. 
Title: Re: What's this clonk?
Post by: Pfreen on Monday,September 30, 2024, 11:32:33 AM
I had a clonk which turned out to be the radiator bolts at the bottom.  The fiberglass nose of the Europa is not supported very well.
Title: Re: What's this clonk?
Post by: Kendo on Monday,September 30, 2024, 03:07:32 PM
Yes, it really needs that closing plate. I drove mine around for a very short while without the plate. And the nose porpoised a lot. I quickly reattached the plate. :-[
Title: Re: What's this clonk?
Post by: HoraceM22 on Sunday,October 13, 2024, 07:33:39 AM
Needless to say, when my nephew came and we tried replicating this,  it didn't do it. More grrrrrr.
Title: Re: What's this clonk?
Post by: 69merc on Tuesday,October 15, 2024, 06:24:46 AM
Mine had a “similar”  clunking noise rolling in the driveway after I got it back on the road.  After I put the rear drive shafts back together, I forgot to “release” the ujoints after I installed them.  I good hammer thwack on the unjoints solved my mysterious clunking.  Just something to try.
Title: Re: What's this clonk?
Post by: Kendo on Tuesday,October 15, 2024, 08:32:16 AM
What is “releasing” u joints? I don’t remember doing that when I replaced mine, and they don’t clonk.
Title: Re: What's this clonk?
Post by: Triton on Tuesday,October 15, 2024, 10:46:14 AM
When replacing  a u/j   sometimes the joint can be tight in a certain position. A few taps around the joint will usually sort it. I don't think it would make a noise but probably a vibration......
Title: Re: What's this clonk?
Post by: Kendo on Tuesday,October 15, 2024, 12:14:46 PM
Is that because some of the roller bearings are not quite lined up? When I replaced my ujs, I worried about the bearings staying in place as I pushed in the caps.
Title: Re: What's this clonk?
Post by: BDA on Tuesday,October 15, 2024, 12:38:03 PM
It helps to smear some (more) grease on the pins when you assemble the U-joint. That way they are more likely to stick to the cup and not get caught by the cross when you press them together.
Title: Re: What's this clonk?
Post by: Triton on Tuesday,October 15, 2024, 01:11:19 PM
As  BDA says , I always press a bit more grease into the rollers.   If  a roller has fallen over i don't  think there would be room to get the circlip in but not 100% sure about that. It's always easier with another pair of hands.....
Title: Re: What's this clonk?
Post by: BDA on Tuesday,October 15, 2024, 01:33:44 PM
If a needle falls over or is bent when you press the cross into the cup, you'll know!! If it just falls to the bottom of the cup, you should be able to use it again but if you bent a needle and you have the old U-joint, you can steal replacement needles from it. If not, you can get by with one or two less needles in the short term (eg. you need the car on the road quickly) but I'd start getting ready to install a new U-joint at your next opportunity and I would drive it pretty gently till then.
Title: Re: What's this clonk?
Post by: HoraceM22 on Thursday,November 14, 2024, 12:47:03 PM
Well bugger me. I've found it.
When taking my car out for a charity meet at the Classic Car Show last weekend, I again noticed this strange noise, but this time as it was early in the morning and nothing was going to be about, when I heard this noise, I just stopped immediately and got out of the car to AGAIN try and investigate what might be causing it and to my surprise, I found that what had been apparently coming from the back of the car was actually caused by the outer edge of the front R/H tyre scraping against front fold on the aluminium plate below the door.
This just now requires a gentle? tap to move it back against the wheel arch.
How annoying but at least that is another problem solved
Title: Re: What's this clonk?
Post by: BDA on Thursday,November 14, 2024, 01:13:27 PM
Glad you found it! I don't think a tap will do it since it's fiberglass. I would get some 3M double stick badge tape or maybe a pop rivet. I think they were pop rivetted from the factory.
Title: Re: What's this clonk?
Post by: Bryan Boyle on Thursday,November 14, 2024, 01:23:51 PM
Glad you found it! I don't think a tap will do it since it's fiberglass. I would get some 3M double stick badge tape or maybe a pop rivet. I think they were pop rivetted from the factory.

You are correct, Jim; looks like the rivet either departed the body, or the head wore through the fiberglass of the lower sill trim piece.  Either way, that flap has to be attached back to the body (I don't think double face trim tape alone would work for very long; you may have to go one size up in pop rivet...)
Title: Re: What's this clonk?
Post by: 314159td on Thursday,November 14, 2024, 01:58:29 PM
They make awesome little splittly rivets for fiberglass for those not familiar yet.

McMaster-Carr (https://www.mcmaster.com/products/rivets/high-strength-blind-rivets-for-soft-materials/?s=Pop+Rivet)
Title: Re: What's this clonk?
Post by: jbcollier on Thursday,November 14, 2024, 04:11:29 PM
Looks to me like your a-arms have slid off their pivot bushings.
Title: Re: What's this clonk?
Post by: Dilkris on Friday,November 15, 2024, 04:53:50 AM
Well bugger me. I've found it.
When taking my car out for a charity meet at the Classic Car Show last weekend, I again noticed this strange noise, but this time as it was early in the morning and nothing was going to be about, when I heard this noise, I just stopped immediately and got out of the car to AGAIN try and investigate what might be causing it and to my surprise, I found that what had been apparently coming from the back of the car was actually caused by the outer edge of the front R/H tyre scraping against front fold on the aluminium plate below the door.
This just now requires a gentle? tap to move it back against the wheel arch.
How annoying but at least that is another problem solved

Are you sure about this H? It is only the trim out of place?
Is the car tracking normally or pulling to one side?
Not wishing to promote "gloom and doom" H but I would have a look at the front suspension wear points - all good??
Title: Re: What's this clonk?
Post by: Fotog on Sunday,November 17, 2024, 07:30:10 PM
Looks to me like your a-arms have slid off their pivot bushings.
Interesting!  What are you observing that makes you draw that conclusion, JB?
Title: Re: What's this clonk?
Post by: jbcollier on Monday,November 18, 2024, 05:44:39 PM
The fact that the tire is so close to the body.
Title: Re: What's this clonk?
Post by: Fotog on Monday,November 18, 2024, 08:06:59 PM
Thanks.  I was wondering if that was it. 😊
Title: Re: What's this clonk?
Post by: HoraceM22 on Thursday,November 28, 2024, 06:14:12 AM
It wasn't touching the body, it was touching the "alloy" trim plate that hadn't been full folded to 90 degrees. However, when I tried to  tap it back it appeared to be metal, but some sort of composite stuff. Strange. However after a bit of a tap come cutting away with a Stanley knife (craft knife) it immediately cured the problem.  Hurrahh!
Title: Re: What's this clonk?
Post by: Kendo on Thursday,November 28, 2024, 08:21:01 AM
Those trim pieces are made of fiberglass. I found that careful use of a heat gun softened the piece enough to let me form it around that bend.