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TR2/3/3A Hood - Rattle

SteveBones

Jedi Trainee
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My problem is with my 1958 TR3A hood. At approximately 1200 to 1500 rpm there is a rattle. Looks like the previous owner removed the felt strip that fits between the support bracing and the hood. The bracing is located toward the back section of the hood closest to the air vent. I can press down on this section of the hood (back edge) and the rattle stops. When I remove the pressure the rattle noise returns.

I purchased and installed a felt strip between the support bracing and the hood. This did not fix the rattle. Any suggestions would be helpful. I can post pictures that show the area I am referring to including the felt strip if needed.

Thanks,
 

M_Pied_Lourd

Darth Vader
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Hi Steve,

Is it possible you bonnet prop rod is rattling ? I know that these can be issues as well.

The other thing to look at is your spring loaded popper mechanism.

Cheers
Tush
 
OP
S

SteveBones

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Hi Tush,

I will check the prop rod. I did check the spring loaded popper mechanism recently and it is good to go.

Thanks for the suggestions.

Hi Steve,

Is it possible you bonnet prop rod is rattling ? I know that these can be issues as well.

The other thing to look at is your spring loaded popper mechanism.

Cheers
Tush
 

CJD

Yoda
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The spring rod should lock into the slot under the bonnet, essentially locking it to the bonnet if the fit is correct. If the rod doesn't enter the slot, it can squeak or rattle against the bottom of the bonnet.

It is essential that the rubber bump stops are not hardened with age too. Fresh stops will prevent movement of the bonnet. The dzeus should be rather tight to lock, so they will also hold the bonnet down firmly.

It sounds like you already filled the gap above the rear bonnet brace.

If you take care of the above, then the last possibility is the prop rod, like Tush mentions...and that is a biggy! There have been several threads about owners trying to silence the prop rod. I think many, like Geo, have even placed a snubber hose around the rod near mid length to prevent it from hitting the bottom of the bonnet. I have never had an issue, but I spent a couple hours adjusting the bonnet prop rod until I was satisfied it worked correctly when both down and stowed.

Oh...hinges are also possible, if they are really worn out or loose.
 

M_Pied_Lourd

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I think I remember that someone even wrapped the connection point of the prop rod with dental floss :smile:

Cheers
Tush
 

6TTR3A

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OK, Another possibility; The hood doesn't quite touch the scuttle (1/32" - 1/64" gap)
Not enough to notice., but enough to create a vibration (aka rattle) at certain RPMs.
Temporarily insert two pieces of corrugated cardboard about 1/2" thick on the scuttle
about two inches outboard of both sides of the scuttle vent to where they get wedged
on the hood when you close it.
If that solves the problem (it did with mine), replace the cardboard dabs of
clear silicone on the hood so it will be less visible. In certain instances you have
to put them on the scuttle. Let them dry for a day.
An alternate to the silicone is an adjustment to the clearance between the hood
and the scuttle. You can change that by adjusting the hood hinges, but be careful
of the clearance at the front between the hood and the apron.
Frank

 
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SteveBones

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Hi John,

Thanks for pointing these items out. Now I know where to continue hunting. I was only focused on the gap above the rear bonnet brace.

Hinges might be an issue. They are original and based on other original items I have replaced, there has been some wear over the last 60 years.

The spring rod should lock into the slot under the bonnet, essentially locking it to the bonnet if the fit is correct. If the rod doesn't enter the slot, it can squeak or rattle against the bottom of the bonnet.

It is essential that the rubber bump stops are not hardened with age too. Fresh stops will prevent movement of the bonnet. The dzeus should be rather tight to lock, so they will also hold the bonnet down firmly.

It sounds like you already filled the gap above the rear bonnet brace.

If you take care of the above, then the last possibility is the prop rod, like Tush mentions...and that is a biggy! There have been several threads about owners trying to silence the prop rod. I think many, like Geo, have even placed a snubber hose around the rod near mid length to prevent it from hitting the bottom of the bonnet. I have never had an issue, but I spent a couple hours adjusting the bonnet prop rod until I was satisfied it worked correctly when both down and stowed.

Oh...hinges are also possible, if they are really worn out or loose.
 
OP
S

SteveBones

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Hi Frank,

Interesting area to consider. I will try adjusting the hood hinges. There is a gasket used between the hinge and the bonnet. I am thinking I could vary the number of gaskets to adjust the hood hinges. I will give it try after checking the other areas mentioned. Next step will be to check the latch and distance of the rubber hood stops.


OK, Another possibility; The hood doesn't quite touch the scuttle (1/32" - 1/64" gap)
Not enough to notice., but enough to create a vibration (aka rattle) at certain RPMs.
Temporarily insert two pieces of corrugated cardboard about 1/2" thick on the scuttle
about two inches outboard of both sides of the scuttle vent to where they get wedged
on the hood when you close it.
If that solves the problem (it did with mine), replace the cardboard dabs of
clear silicone on the hood so it will be less visible. In certain instances you have
to put them on the scuttle. Let them dry for a day.
An alternate to the silicone is an adjustment to the clearance between the hood
and the scuttle. You can change that by adjusting the hood hinges, but be careful
of the clearance at the front between the hood and the apron.
Frank

 
OP
S

SteveBones

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Thanks Tush - I will be checking the prop rod in addition to the rubber stops to see if the height needs to be adjusted.
 

TexasKnucklehead

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Ah yes, the infamous idle speed hood rattle. That's a fun one. One of our club members showed me a little trick you might want to try, just for the fun of it. It worked on his TR3 as well as mine. If you take the Dzus key, and insert it into the socket in the hood, while the hood is rattling, the rattle will stop when you turn the key 1/4 turn. Either side, every time.

Obviously, the rattle has nothing to do with the position of the Dzus locking mechanism, but it will show you how subtle the circumstances are to make it happen. After nearly countless failed attempts at stopping my rattle, I now have a rubber bushing from the front suspension slipped around the prop rod at the end farthest from the hinge. It hasn't rattled for some time but that's not to say I wouldn't be surprised if it starts tomorrow.

Good luck, let us know what works.
 

sp53

Yoda
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Hey check and see if the hood rod itself is not hitting right at the tip of the small 90 degree bend that is about an inch long when closed in the rubber holder. The originals are much shorter maybe ½ inch and the tip on the shorter one will not be near enough to the hood when in the rubber holder. In other words open the hood and look up at the rod while it isin the holder and see how close the tip end is to the hood.
 

Don Elliott

Obi Wan
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To isolate the source of the rattle, try the following. Take a large soft sponge that you might use when washing your car. Fit it between the prop rod that you normally use to hold up the bonnet (hood). Insert tye sponge just before you close the hood and Dzus it securely. In my case the rattle was no longer there.

The problem is that the sponge may slip out of place when driving but it will also fall out when you open the hood and pull out the support prop rod.
 

M_Pied_Lourd

Darth Vader
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Good to see you Don:cool:

Cheers
Tush
 

CJD

Yoda
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Hey check and see if the hood rod itself is not hitting right at the tip of the small 90 degree bend that is about an inch long when closed in the rubber holder. The originals are much shorter maybe ½ inch and the tip on the shorter one will not be near enough to the hood when in the rubber holder. In other words open the hood and look up at the rod while it isin the holder and see how close the tip end is to the hood.

That explains a lot. I really had to work my repro rod to make it work. Still, I have to be careful when setting the rod not to lift the bonnet so far that it hits the scuttle. I thought it was an issue with the car...but it makes sense that the rod is too long, causing all the problems reworking it too!
 
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SteveBones

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Hi Tex,

Thanks for the suggestion. I finally was able to check the prop rod earlier today. I had already checked on the other areas before starting this post. It took me a few days to look at the prop rod because I got sick (just a cold). Turns out the prop rod connection nut & bolt was really loose. I did not even think to check this before being suggested in these posts. That would have been too easy I guess. Still not feeling up to going for a test drive, but pretty sure this is causing the rattle. Prior to this I finished rebuilding the front suspension and having the radiator core replaced. First time I rebuilt the front suspension on a TR. I am really happy with how the car rides.

I was thinking about the TR4 I own and why no hood-bonnet rattle. The bonnet has a threaded nut that is fixed (welded?) where the prop rod connects. I do not have the prop rod installed. I just leave it under the carpet and pull it out when needed. I guess this explains why I never had to deal with this before. I have close to 40 years of owning various TR4's and only 2 years owning this TR3A.

Thanks again everyone for the great suggestions. I now feel kinda like an expert when it comes to TR3 bonnet rattles.

Ah yes, the infamous idle speed hood rattle. That's a fun one. One of our club members showed me a little trick you might want to try, just for the fun of it. It worked on his TR3 as well as mine. If you take the Dzus key, and insert it into the socket in the hood, while the hood is rattling, the rattle will stop when you turn the key 1/4 turn. Either side, every time.

Obviously, the rattle has nothing to do with the position of the Dzus locking mechanism, but it will show you how subtle the circumstances are to make it happen. After nearly countless failed attempts at stopping my rattle, I now have a rubber bushing from the front suspension slipped around the prop rod at the end farthest from the hinge. It hasn't rattled for some time but that's not to say I wouldn't be surprised if it starts tomorrow.

Good luck, let us know what works.
 
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