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Discussion Starter · #1 ·
Just wondering if anyone knows what rim offset(ie ET40), and bolt pattern(ie 5x100) the Opel GT is, and how wide and big of a rim and tire you can fit in the stock wheel well.

Also, What are some modifications that can be done without Taking the engine apart, that will make a noticeable difference, in power.


Discussion Starter · #3 ·
I think the reason you´ve had no replies is because it´s kind of a loaded question. Nobody wants to write such an involved answer! There are many factors which will affect the largest wheel/tire combo you can fit. The most critical being ride height.

The stock rim size is 13 x 5 inch, with a 4 inch backspacing. Bolt pattern is 4 x 100. I tend not to use offsets as a reference, since comparing different rim widths throws a wrench in the offset equation. A 40 mm offset on a 6 inch rim will have a different backspacing than a 40 mm offset on an 8 inch rim. Many people assume it´s the same, and find out the hard way when a new wheel doesn´t fit.

Anyway, for starters, what are you attempting to do with the car? Are the larger wheels/tire primarily for appearance, or for performance enhancement? The largest tire is not always the best choice for performance, which is why I ask. Are you limiting yourself to any particular rim diameter as a maximum? 15? 16? 17? Larger? Just trying to narrow down the field a bit, so you may get a better chance of some replies to your query.

Oh, and as far as one of your other questions goes, what year is the engine in your car?


Discussion Starter · #4 ·
wheels etc.etc.

OK I´ll take a shot,
RallyBob is most Correct in his statement "rim size 13 x 5 4 in. backspacing and 4 x 100 bolt pattern stock" as far as largest wheel in stock wheel well I would say 15 x 7 simply because this offers you the best choice of tires per application ( for summer / winter/ racing etc.) any wider than this on a stock wheel well and you will possibly see your tires as they throw mud and road grime all over your nice paint job. Any taller and you lose the advantage of cheaper tires due to low profile costs etc. etc. and lets not forget about turning circumfrence. And also the strain wide tires can put on your other mechanicals.
As far as additions to Engine: #1 research in this i mean read every thing you can expecially this web board you have here some of the best people when it comes to getting every ounce of HP available. #2 Almost everything, in this i mean ... aftermarket electronic ignition, a/m carb , a/m breather, plug wires, a/m header
the list goes on and on. :D

Discussion Starter · #5 ·
I´m going for a nice combination of appearance and performance. I don´t want some big 17" rims on this car, I was thinking that the biggest I would be looking at would be 15 inchers, maybe 16", just wanted to see what other´s thought though.
15x7 sounds like what I was hoping for.
what offset would I need for 15x7" rims?

I don´t have the car yet, I´m going to go take a look at it in a few weeks. A friend of mine´s brother owns the car. Last time my friend went out to his brother´s he took some footage of it for me. It looked like it was in good condition. The paint job was good, and there was no visible rust. He said the car needs a new fuel pump, and that´s the only problem with it, he also said he had the engine rebuilt 1 year ago. Is the Fuel pump a big deal? I found a website http://www.opelgtsource.com/
and they have a fuel pump for the 1.9L at $33!! This seems very cheap to me, does that seem right? Also, has anyone dealt with Opelgt source before?

I´m not sure on what year the car even is... Neither is he. But one weird thing I noticed in the video was that the headlights weren´t the flip around kind... they were a little further towards the front of the car, and they were stationary there. Is this some weird model of Opel GT? cause I haven´t seen any with the lights like that before..

Sorry for all the questions. I´m just very interested in this car, and don´t want to get something that I won´t be able to get running well.

He said he would sell me the car for $1200 CAD, which translates to around $750 USD. Is that asking too much, for the condition? It seemed pretty good to me, as I don´t think it needs any body or engine, or even interior work.


Discussion Starter · #6 ·
Go For It!

Hey Thehoj,
That Doesn´t sound like a bad price at all , and if you like it go for it!As for back spacing I have rims with 3" measured B/S but with mods made to headlights I would definitely check the car out closer before i spent money on rims.(you never know what kind of genius engineering your are likely to find) As for the fuel pump that isn´t too bad either I found one at a auto parts store (CarQuest) for $18.00 but they pulled it from back east. Also Rebuilt which is reason for less cost.And yes I am Sure almost everyone with an Opel GT has dealt with OGTS they are great people and do a great courtesy to opelers everywhere. You should be able to check the ID plate to get the year (this is located under the hood below the pass. side windshield ).Or the title? The 72 GT I have is like this with the headlights I do not think it came that way just that the headlight cable froze up then instead of fixing it they used body filler around the headlights then reinstalled headlights below in the nose area. It Doesn´t look bad I am just happy my 70 isnt that way. When and if you get it I wish you the happiest of experiences and have fun!

Discussion Starter · #7 ·

Thanks for the info!!

I´m not in a rush to upgrade the rims or anything, I´m just trying to find out as much as I can about the car, and wasn´t able to find any info out about the rim size, etc..

I´ve heard that the later year Opel GT´s had to reduce emissions or something?? Is this true, that they are substancially restricted?
If so, can this emissions control stuff be removed without taking apart the engine?
I would have thought that any emissions control would be handled in the exhaust system, but on a website I was looking at, they said that they also lowered the compression of the engine to assist in this...
Is this info out to lunch, or correct?

thanks for your help.

Discussion Starter · #8 ·
They did numerous things to lower emissions. They dropped the compression ratio with different pistons, switched to a smaller cam with hydraulic lifters instead of solids, changed the Solex carburetor model, changed distributors and timing curves over the years, changed intake manifolds numerous times, and later on even had an EGR system. Early cars with CA emissions had air pumps too.

Discussion Starter · #10 ·

The 1970 Opel GT by far definitely, definitely, oops I forgot i am biased I own one. Seriously they are all great cars. :D

Discussion Starter · #11 ·
Man, I´m just full of questions.

Do you know what the body was made of?
Someone told me fiberglass, but I don´t think so.

Discussion Starter · #12 ·
It is made of metal and very prone to rusting i might add.seems like road deposits love to find thier way into every little nook and cranny on these puppys. Not to mention all the added pieces that love to trap moisture.
Most of my Opel seems to be made from 22 to 24 guage metal gets thinner (24 guage) in the fender area. Just Starting body now. It is hell to have a fun car that looks like a POS. I believe i pulled off 200 pounds of allmetal and a little bondo. The ugliest car i ever seen laid beneath. So i am now going to learn "structural machining" for lack of a better word.
I have a machinist who is willing to build me a set of metal rollers to get the curves for wider fender flares and body parts massaged out of sheets of 22 guage metal (cold rolled).I will try to have pictures taken when i do this but that is for summer.

Discussion Starter · #13 ·
I gather from your comment on CAD $ that you are a fellow Canuck. What part? I myself am in Calgary, and there are a few other Opels in and around Alberta. Most notably Katheryn McCoy in Leduc, who as of this weekend owns a GT, a Manta, a Kadett and an Ascona SportWagon. She has imprted three of these from the USA.
Wherever you are, this and the yahoo classicopels site ( http://groups.yahoo.com/group/classicopels )
are where you want to be if you want to learn about Opels. And as for OpelGT Source, they have a better supply of Opel parts than was available from the Buick dealer back when I bought my first GT, which was in 1977 when the car was only 6 years old, and are very familar with shipping parts to Canada.

Good luck.

Discussion Starter · #14 ·
Thanks for the info on the body.

And as for kwilford, yes I´m from Canada.. Brandon Manitoba to be exact. That´s 200 KM West of Winnipeg in case you didn´t know. There aren´t too many Opel GT´s around this part, in fact I don´t think I´ve ever seen one in Manitoba.. So if there are any, they´re all in storage.

Thanks for the classicopels link, and info on Opelgtsource shipping to Canada. I´m gonna need to order that fuel pump from them.

On another note, I was just wondering what the chances of the Opel GT I´m looking at being a 1.1 litre?
I haven´t actually talked to the owner of it yet, just my friend who is the brother, and all he knew was that it was a 4 cylinder... I´m really hoping it´s the 1.9 litre.

Thanks everyone.

Discussion Starter · #15 ·
1.1 litre

Don´t worry about it being a 1.1 litre. If it is, it really isn´t too difficult to change over to 1.9, and I´d gladly come up with a couple of 1.9´s for you to trade for a 1.1 if it came to it. I REALLY want a 1.1 litre for mu Kadett! :D

Discussion Starter · #16 ·
Wheels Pain

OK everything you need to know about wheels is at http://www.opelclub.com/public/blitz/ after you get there click on the link. But even armed with the information this gives you will encounter idiots who will refuse to sell you wheels unless Opel GT is listed in there files, and most places never heard of Opel. ( SAD!!! ) The best thing to do is tell these people that you own a 1977 BMW 320i. You can look up BMW 320i at www.ronalusa.com and www.tirerack.com to see some of the wheel styles you can get to fit your opel.

Discussion Starter · #17 ·
1.1 GTs are fairly rare, chances are its a 1.9. If it is a 1.1 its worth more because of the rarity. You can always go out and purchase another Opel with 1.9 instead of converting the 1.1.
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