TR2/3/3A TR3 Bonnet Rattle

[Moseso]

Here's one I haven't seen discussed, though I'm sure it's epidemic amongst sidescreen TRs...

The Dzus fasteners hold the bonnet down at the edges, and the push-up spring applies its force near the center. At an engine speed near idle, this arrangement vibrates making an unholy racket. WD-40 and/or oil on the spring plunger takes the high-pitched squeak factor out of the noise, but has hardly silenced it. Now it just sounds like the bonnet rattling. You can even see it when it's happening.

I think I have the fasteners and pads adjusted properly, so that the bonnet is held down securely, but I don't think that's the the real source of the noise anyway, even if they were a little loose.

Who else is offended by this rattle?

Has anyone devised a cure?

 

[Geo Hahn]

Sounds to me like your rubber pedestal pads are not adjusted high enough. Anyway, I do not experience that rattle... when I twist the dzus everything clamps down tight. My rubber pads get a bit deformed from the pressure of the bonnet against them -- do yours?

 

[NickMorgan]

I have two rattles from my bonnet when the engine is idling. One is the bonnet support bar that is rattling around on its mounting bracket. The other is caused by wear in the hinges. I am sure that they could both be cured reasonably easily. I just consider it part of the character of the car!

 

[TR3driver]

As Geo says, get the adjustments so tight that it deforms the rubber stops as you tighten the Dzus buttons. You may also need to remove some of the shims under the Dzus sockets.

For me, that reduced but did not eliminate the vibration in the center. I just kept the plunger greased, since for me, the noise was the plunger squeaking in it's hole.

A local club member actually disassembled his plunger unit and opened up the holes for nylon bushings. He also added more rubber bump stops at the rear of the bonnet, to keep the rear from shaking.

 

[MGTF1250Dave]

Aloha Moseso,

I think Geo, Nick and Randall have identified all the usual suspects. I put some nylon washers in the bonnet prop rod attachment which in my case removed that low frequency metal rattle. Now that type of noise indicates to me that I have a hinge working loose. I also had a high pitched metal on metal racket that came from the plunger/hood lift assembly. I discovered that over time the plunger rod had vibrated against the hole in the plate to the point of have a slot worn deeply in it and the hole ovaled out. I did the same thing Randall's friend did, I drilled out the hole for a plastic bushing and had the slot closed by welding. It solved the problem.

 

[Moseso]

Thanks for the tips, guys!

I'll try tightening the bumpers at the front, to start. My hinges are new, and freshly installed, so I'm reasonably certain that's not where the fix will be found.

Randall -- The extra bumpers you mentioned -- are those just another pair installed in the fender joint, like the ones in the front, or something else, nearer the center of the bonnet?

 

[vivdownunder]

Sometimes the spring steel washers that retain the Dzuz fasteners rattle like crazy. They are at their worst with the bonnet up and motor running, and drives you nuts if you are trying to tune the engine.

I cut out a pair of thin (1mm) rubber washers and punched centre holes the same diameter as the Dzuz. Then I cut a slot in the washers just slightly smaller than the Dzuz diameter, and pushed them in, one each side, between the Dzuz metal washer and the bonnet.

This cushioned the Dzuz metal washers and ended that rattle for once and all.

 

[TR3driver]

I believe Bob Jasper just installed bump stops in place of the fender bolts at the rear, similar to the front.

But come to think of it, I ran some rubber weather stripping across the back of the bonnet, which helped keep the hinge pins from rattling, a little.

 

[mrv8q]

Like Nick, I think my rattle comes from the prop rod, but from the front,not from the rubber holding side. I found a bunch of dental floss wrapped around the rivet that allows the prop rod to pivot quieted things down for awhile.....

 

[Don Elliott]

Mine vibrates between 800 and 1200 RPM. Usually I'm stopped at a traffic light and everyone looks to see what that rattle vibration is. I would like to believe that they are admiring my 1958 TR3A, but until I pull back the gas pedal to below 800 RPM or step on the gas to above 1200 RPM, the infernal vibration is there. And it's LOUD !

I have proven that it is the spring-loaded thingy attached to the front valance. All I have to do to prove to others that my engine is not going to explode is to put my fist gently on the bonnet just above where that spring is and apply a bit of pressure downwards The sound disappears.

I would like to design and build a teflon or nylon bushing (or two) into the original design in such a way that the vibration is no longer there, but a design which will retain the "original" appearance as far as a concours judge can see.

 

[Twosheds]

I'm like Nick. I just live with it.

It's a funky old car, shouldn't it rattle?

 

[6TTR3A]

I did most everything listed above & still had the 800RPM-1000RPM rattle.
Finally I put a dollop of clear silicone in the rear center of the bonnet under the lip, out of sight. Let it dry for a day----BINGO!!

I used fat "O" rings instead of rubber washers as vivdownunder suggested
on the druz fasteners.

Now let's talk about the "clunk" in the rear....No, it's not a loose shock !
FRank

 

[Moseso]

I did most everything listed above & still had the 800RPM-1000RPM rattle.
Finally I put a dollop of clear silicone in the rear center of the bonnet under the lip, out of sight. Let it dry for a day----BINGO!!

Now <span style="font-style: italic">that's</span> what I'm talkin' 'bout! I've been trying to imagine a bumper of some sort, center-front, that would prevent this infernal vibration. It probably wouldn't be to hard too fabricate/attach something to the cowl bar, next to the push-up rod. It would have to be adjusted just right, so that it didn't hold the bonnet up, when closed, but <span style="font-style: italic">would</span> keep it from shaking at 950 RPM.

Mine vibrates between 800 and 1200 RPM. Usually I'm stopped at a traffic light and everyone looks to see what that rattle vibration is. I would like to believe that they are admiring my 1958 TR3A, but until I pull back the gas pedal to below 800 RPM or step on the gas to above 1200 RPM, the infernal vibration is there. And it's LOUD!

I <span style="font-style: italic">knew</span> I wasn't the only one! That's a beautiful description of an ugly noise, Don. My throttle linkage has got just a little hitch in it too. If I don't toe-up on the pedal, it idles right at the resonant frequency of the bonnet. When I do toe it up, the RPMs drop another 100, or so, and the noise goes away.

So -- while we're at it -- does anyone's throttle linkage work better than Don's and mine? If so, how did you do that? Or is it just another of the TR3 peculiarities?

 

[TR3driver]

So -- while we're at it -- does anyone's throttle linkage work better than Don's and mine? If so, how did you do that? Or is it just another of the TR3 peculiarities?

In my case there were two problems.

One was that the balls in the linkage were severely worn to an oval shape. Replacing all the joints solved that. (Was a long time ago, ISTR I found them at a truck repair place.)

The other was that the carbs were worn enough to allow the throttle plates to drag on the carb throats. Rebushing the carbs solved that.

Oh yeah, I also wound the return springs on each carb a bit tighter than they had been before; and put a drop of oil at each pivot point (especially where the shaft goes through the carbs) during yearly lube service.

 

[vivdownunder]

Also with throttle linkages, the bellcrank beneath the front carbie seems to always miss out on a lube. It dries out with nearby exhaust heat and the bushing soon wears to oversize, with the slack causing loss of throttle pedal travel.

Back to rattles....one near the sprung bonnet lift often comes from a loose pivot fixing for the bonnet stay rod. Again, a rubber washer either side of the rod does the trick.

The bonnet lift itself squeaks where it passes through its housing, unless lubed or bushed as others describe.

More rubber washers on the radiator stays on the inner guards helps absorb flexing which eventually fractures the radiator side brackets.

Fair dinkum, it's hard to explain the time spent in a plumbing supplies shop trying stop the rattles in a TR. And just so that nothing detracts from the really loud exhaust !!!

 

[Don Elliott]

When I did my restoration, I pulled a long piece (about 3 feet long) of soft jute-like fiber matting (a bit like carpet underlay) out from the rear of my bonnet. It was sandwiched into the clannel cross piece that would be just above the battery when the bonnet is closed.

This cross piece is like a steel channel but is not spot welded tightly along one side.

I had always intended to put the felt back in some day but never have. I still have that piece. It's over 50 years old now, but still looks reasonably nice. Another winter project if I can squeese it back in between the spot welds.

Maybe the silicone is absorbing the vibration like the felt fiber strip is supposed to. I'll give it a try.

 

[Moseso]

Hmm. That sounds easy enough, though I keep thinking that it's the front edge that needs to be damped. I bought some felt to pack under my fuel tank and there will be plenty left over. Certainly easy enough to try that -- so I will -- next Spring when I can drive again.

 

[sp53]

How synchronistic Don, I was finishing the prep work on the hood of my 61 yesterday and noticed this piece of something, so I tugged at it and out came this 2+ foot by 4inch by 3/16 piece of felt. It had been in there from factory. I showed it to the paint guy and he said hum you hang to it. I will put some card board in for now. I think the felt piece is important and perhaps some kind of silencer and shock absorber/ expansion joint thingy because I can easily push the metal down when it is not in there. I guess they figured if the felt got wet the heat from the engine would dry it off. I admire the engineering of these cars.

 

[6TTR3A]

I don't remember any felt but I remember seeing a 3rd buffer on a late 3A or a 3B, so after I did mine, (& was plagued with rattles) I fabricated one & it helped a lot.
I found my sketch in my records box. I'm too lazy to figure out how to include photos here so I emailed them to you.
FRank]

 

[Moseso]

Here's the pix Frank emailed me. It's pretty much <span style="font-style: italic">exactly</span> what I was thinking!