TR4/4A Rear bonnet seal

Rut

Obi Wan

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• Oct 2, 2017

• #1

Trying to figure out the orientation of the rear bonnet seal, does the lip face forward or back? If it's facing forward it rests on the bonnet bracing and if it faces to the rear it fits snugly between the bonnet bracing and the rear edge. Piggott's book shows the lip facing forward, but that jacks up the bonnet. Thoughts?
Thanks, Rut

 

Geo Hahn

Yoda

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• Oct 2, 2017

• #2

On mine, which I believe is original in this regard, the flange is on the forward side but is curved rearward. Looking for a pic...

Here:

 

OP

Rut

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• Oct 2, 2017

• #3

George,
Thank you, that's exactly what I was looking for! I've turned mine around to face the rear as yours is pictured...it just makes sense when you look at the way the bonnet fits when closed.
Thanks, Rut

 

KVH

Darth Vader

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• Oct 3, 2017

• #4

Does that seal require any kind of silicone or adhesive? I meant to be in bed by now, but I've been ogling Geo's engine compartment for several hours, overcome by that feeling of all there is still to accomplish.

 

Popeye

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• Oct 3, 2017

• #5

KVH said:

I meant to be in bed by now, but I've been ogling Geo's engine compartment for several hours, overcome by that feeling of all there is still to accomplish.

Click to expand...

Heinzelmännchen? (https://en.wikipedia.org/wiki/Heinzelmännchen)

"The little house gnomes are said to have done all the work of the citizens of Cologne during the night, so that the inhabitants of Cologne could be very lazy during the day. According to the legend, this went on until a tailor's wife got so curious to see the gnomes that she scattered peas onto the floor of the workshop to make the gnomes slip and fall. The gnomes, being infuriated, disappeared and never returned. From that time on, the citizens of Cologne had to do all their work by themselves."

But seriously, that is a gorgeous engine compartment. Hopefully we will all be there in a few years...

 

Popeye

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• Oct 3, 2017

• #6

And to add to the mystery, in my car it appears to have been facing forward. Cannot say that the seal is original, but it sure was old when removed. I have not yet re-assembled, and have not had to make the decision on how to best install.

 

Last edited: Oct 3, 2017

OP

Rut

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• Oct 3, 2017

• #7

Since we are discussing 66 TR4as, mine has SUs and George's has ZS carbs...was there a change in 66? My 67 has SUs as well.
Thanks, Rut

 

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Marvin Gruber

Yoda

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• Oct 3, 2017

• #8

Can't give you any factory info but quite common to see both types of carbs on the 4A cars. I have cars now with SUs and ZS carbs. I do like the SUs better than the early ZS. I seem to remember seeing more SUs on the the 67 cars.
Marv

 

Merlin63Tr4

Jedi Trainee

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• Oct 3, 2017

• #9

My '63 Tr4 has that particular seal installed with the lip facing forward, I think the seal is installed in that orientation to help the seal contain the fumes/smells from the engine compartment.
Yes, I did replace the seal, but I installed the new seal in the same orientation as I found the old one.
And yes that is a '63Tr4 engine with a Tr4A PCV system and coolant recovery bottle, etc.
M.

 

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Last edited: Oct 3, 2017

Popeye

Darth Vader

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• Oct 3, 2017

• #10

Maybe it was forward seals and SU's on Monday, and backwards and ZS's on Friday?

 

Geo Hahn

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• Oct 3, 2017

• #11

Now I wonder if mine is 'incorrect' or if indeed it was a case of 'installers choice'.

 

Merlin63Tr4

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• Oct 3, 2017

• #12

Geo,
I don't know what to tell you, but the rear bonnet seal on my '63Tr4 was installed lip forward (toward engine) like in the Workshop Manual illustration and my picture.
I purchased my Tr from the first owner some 38 years ago and believe me that guy didn't replace a thing on it! He was the primordial DPO.

M.

 

OP

Rut

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• Oct 3, 2017

• #13

Thanks for the additional information and I've settled on installing the seal with the lip facing the rear. The bonnet fits much better and the seal rests on the smooth underside vs the rear bonnet braces.
Thanks again, Rut

 

Merlin63Tr4

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• Oct 3, 2017

• #14

Hey Rut,
I don't understand why my seal does not contact the bonnet brace lips when it is installed with the lip forward.
Enclosed is a picture of the profile of my seal (OEM Triumph) does it look like yours?
M.

 

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OP

Rut

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• Oct 4, 2017

• #15

Merlin,
My bonnet seal has the same profile as yours, but if I install it with the lip facing forward it interferes with the bonnet bracing. The flat space on the rear of the bonnet is less than an inch wide in places, so there's not much room for adjustment.
Rut

 

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Geo Hahn

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• Oct 4, 2017

• #16

Merlin63Tr4 said:

...I think the seal is installed in that orientation to help the seal contain the fumes/smells from the engine compartment...

Click to expand...

I pondered that -- but of course installed the opposite way it might help keep rain out of the engine bay.

TR3s apparently don't need no stinkin' seal -- in fact the bonnet is vented just forward of the windscreen to release any fumes & smells.

 

Merlin63Tr4

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• Oct 4, 2017

• #17

Geo,
Don't know about keeping rain out of the engine bay since there is the rear firewall lip and the drains at either end to do that.
But I can tell you that all the cars that I have owned that had a rear hood seal have had the lip or the main part of the seal facing forward, BMWs, Volvos, Fords, Chevys, etc.

M.

 

Merlin63Tr4

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• Oct 4, 2017

• #18

Rut,
I know I'm beating a dead horse, but I don't understand why the seal interferes in your Tr and not in mine?
Questions,
1) are you sure you have pressed the seal home onto the firewall vertical lip, I know mine took some effort to fully seat it.
2) could your bonnet be adjusted too far aft and too low in the rear?
I'm enclosing pics of the seal as installed in my Tr and the bottom of the bonnet. The pic of the bonnet shows the "cleaner" area were the seal seats between the rear bonnet lip and the bonnet reinforcement gusset lip.
M.

 

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OP

Rut

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• Oct 4, 2017

• #19

Merlin,
When the lip of the seal is facing forward it adds additional pressure to the bonnet and the drivers side rides up. With the lip facing to the rear the bonnet is pretty even across the rear and flush with the cowl. No pictures, but I would describe the gap as typical and even with the gap along the sides of the bonnet. Please understand that while working on Desert TR I don't know what has and hasn't been done and Jims brother Steve and I just mounted the bonnet for our trip home. Although it was a quick assembly we did a pretty good job, but more adjustment on the body panels is needed before I'll be satisfied.
Thanks, Rut