I want to reduce the thickness of my car's fibreglass body by grinding away the inner surface. Any idas of what would be the best abrasive pad/disc to use?
Grinding fibreglass
- Thread starter old-git
- Start date
T9 man
TC ModFather
Hi OG, if your not in a hurry for this, I have the beast booked in on Good Friday (18th April) for lots of smart repairs with Matt the body work guru. Matt was the bodywork supervisor for Lexus UK before he branched out on his own. I could ask him the question for you and post it on Friday night 
Or!!! if your free you could pop over and ask him yourself. We will be at Stapleford Abbotts airfield from 09:30 until late afternoon. Might even treat you to a breakfast in the clubhouse if your lucky
Or!!! if your free you could pop over and ask him yourself. We will be at Stapleford Abbotts airfield from 09:30 until late afternoon. Might even treat you to a breakfast in the clubhouse if your lucky
Last edited:
T9 man
TC ModFather
Glad to help OG, that's a real shame about you still working on the Friday :sad2:
The clubhouse breakfast is absolutely marvellous, I will think about you toiling away while I am munching away :bigsmile:
The clubhouse breakfast is absolutely marvellous, I will think about you toiling away while I am munching away :bigsmile:
T9 man
TC ModFather
Right then, I just got in from a long day with Matt the smart repair guru.
OG, don't do it!!!
Matt says that the Lotus Elan has already shaved the thickness of the fibreglass body structure to the bone, so to remove any more of it would be folly. The fibreglass thickness is considered to be borderline with regards to it's strength and rigidity and all due in fact to saving weight. TVR's are also notorious for this and many examples of weakness can be seen by the spiders web cracks that the bodywork develops. Repairs to these cars are mucho dinero apparently.
So in other words OG, save the weight elsewhere and forget the bodywork buddy.
OG, don't do it!!!
Matt says that the Lotus Elan has already shaved the thickness of the fibreglass body structure to the bone, so to remove any more of it would be folly. The fibreglass thickness is considered to be borderline with regards to it's strength and rigidity and all due in fact to saving weight. TVR's are also notorious for this and many examples of weakness can be seen by the spiders web cracks that the bodywork develops. Repairs to these cars are mucho dinero apparently.
So in other words OG, save the weight elsewhere and forget the bodywork buddy.
Thanks for that T9.
I am aware that the body is generally quite thin.
However, one area I wish to lighten is thicker than standard. 20 years ago I added an outer skin with built in arches over the existing front section forward of the windscreen. Although I ground down the top layer I didn't take off as much as I put on.
Also I added rear arches and didn't do a brilliant job underneath so there is quite a bit of fibreglass that needs to be removed in order to tidy it up.
I appreciate the advice but I still want to remove material, so the question remains valid.
I am aware that the body is generally quite thin.
However, one area I wish to lighten is thicker than standard. 20 years ago I added an outer skin with built in arches over the existing front section forward of the windscreen. Although I ground down the top layer I didn't take off as much as I put on.
Also I added rear arches and didn't do a brilliant job underneath so there is quite a bit of fibreglass that needs to be removed in order to tidy it up.
I appreciate the advice but I still want to remove material, so the question remains valid.
T9 man
TC ModFather
OK understood, I shall text him later and explain all that to him and get the info.
SLEEPER
Pro Tuner
- Points
- 592
Normally a little bit of fibreglass will make no difference but as you are taking the weight thing to its limit I can see the point of the question.
I dont hink there is a " best way " you can grind fibreglass away with almost anythng from a bremel to an angle grinder . The problem is that in grinding it away you will lose strenght . How much will be difficult to say unless you are doing it "live"
The very best way would be to fabricate the offerding parts off the car and then in single skin carbon or similar as the weave is stonger although you could do this with grp.
With a door pillar however that wont be easy so maybe its bremal time unless you feel confident with something stronger. The good thing about grp etc is that is you do too much you can always put some back.
Yo are definately right about from the inside as if you go thr ough the gel coat on the outside painting becomes a real pain.
I dont hink there is a " best way " you can grind fibreglass away with almost anythng from a bremel to an angle grinder . The problem is that in grinding it away you will lose strenght . How much will be difficult to say unless you are doing it "live"
The very best way would be to fabricate the offerding parts off the car and then in single skin carbon or similar as the weave is stonger although you could do this with grp.
With a door pillar however that wont be easy so maybe its bremal time unless you feel confident with something stronger. The good thing about grp etc is that is you do too much you can always put some back.
Yo are definately right about from the inside as if you go thr ough the gel coat on the outside painting becomes a real pain.
As mentioned above, I am only looking to remove material from areas that are thicker than original due to modifications I made many years ago. As the body if off the car at present it seems daft not to
I have sitting in the garage 3 rolls of carbon fibre waiting to be transformed into a replacement body. This is planned to be done once the car is up and running and all body mods have been finalised. This should remove between 60-80kg. The boot, bonnet and doors are already carbon.
I have sitting in the garage 3 rolls of carbon fibre waiting to be transformed into a replacement body. This is planned to be done once the car is up and running and all body mods have been finalised. This should remove between 60-80kg. The boot, bonnet and doors are already carbon.
T9 man
TC ModFather
Matt got back to me, you need to use the 120 sanding disc OG. Matt said to make sure you use goggles or safety glasses and a fine particle dust filter for your face. Use slow small circular movements and don't apply any pressure to the sander, let the machine do the work.
T9 man
TC ModFather
Your welcome Steve, it's nice to be able to help you for a change instead of always the other way around 
Your welcome Steve, it's nice to be able to help you for a change instead of always the other way around
You have helped me on more than one occasion:
Scope
Drill
To name but two, so it is me who should be thanking you.
