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GT 5 lug conversions

21K views 34 replies 18 participants last post by  wecycle 
#1 ·
5 lug wheels?

Opel Kadetts and GT's use the same wheel bearings as the Chevette. Fiero's do too, but come with 5X100 hubs and bigger brakes. Has anyone tried to use Fiero or Chevette hubs on an Opel?
Fiero hubs also set the rim mount plane out farther, allowing for more offset (=cheep FWD wheels.)
If noone has tried it, then Saturday I'll pick-up a couple of chevette and fiero hubs at the junk yard and try it for myself! I'll keep you posted if something pans out.
 
#2 ·
What are you accomplishing????

Don't mean to be rude, just objective on this. Are you looking to Mount the fiero hubs to the GT...brakes and all? Also if they did fit, what would we need to do for the rear? We would only have front 5 lug wheels. Is the chevette not a 4 x 100???? Or is this on a newer model chevette? Just some things I would question before I went too deep into the project...but please continue, it may open up a door to having a cheaper big brake package for the front.
 
#3 ·
Yep, 5-lug hubs and all. The fiero front hubs are offset out further to use "front wheel drive" rims, so now 15,16,17,18, and 20" wheels would be available. The intention would be to probably use a set of wheel adapters on the rear to both adapt and offset the rear for matching wheels, at least until I get the new axle finished.
I am actually in the process of mating the spring perches and panhard rod mounts from a spare axle to a cut-down Camaro axle. The front-end needs to firmed-up first though so that I know just how far to cut down the axle and how long the axle shafts need to be. The camaro axle has bosses on the diff to allow a trailing arm to mount and there are no less than 14 options I have found for posi's and lockers. Add to this the amount of available gear ratios, and the flexibility should be great. The axles are expected to run @$5-600 and the posi will be @$250, bringing the total for the project to just over $1200 as an estimate for a posi axle that will hold-up to anything any motor I can fit into the Kadett will put out.
I love my Opels, especially the way they handle, but when you end-up broken down for the 5th time in 4 years in Perry, Oklahoma looking for a mechanic, even an Escort looks good....
 
#4 ·
I can just see your garage....

3 or 4 bays, hydrolic car lifts. Power engine hoists that slide on a rail mounted to the ceiling. Full machine shop. Add to that ,that brain of yours that the Navy filled with all sorts of good stuff and you could be dangerous!!! HA HA HA HA

Good Luck with the wheel project. Let us all know how it comes out.:)
 
#6 ·
Nothing off the shelf. You may be able to redrill the front hubs and rear axle flange for 5 bolts. You'd have to make sure your new holes weren't too close to the old holes however. This may mean that it won't work. Another option would be to swap in another rear axle and use front suspension pieces from another car. It would take some research and work to get it done safely and have the geometry come out right. There is a good deal of inexpensive and very light wide 5 parts out there. You'd likely have to fabricate your own upright however.

For brakes you can order rear discs from OGTS($$$) or do Charles's Isuzu swap. These should be used with upgraded master cylinders...although there is some debate over this. OGTS has big front vented brakes as well. There is also RallyBobs Chrysler/wilwood conversion wich has been discussed on the classicopels list.



-Travis
 
#7 ·
Hads anyone converted their front suspension to use a 5 lug spindle? I 'm thinking of possibly grafting in a 5 lug that can fit Chevy wheels and brakes. The front seems as though it will be the hardest to change over. I'm also going to check with some street rod chassis guys I know. I'll let the list know what I find out.
 
#8 ·
Don't quote me directly on this, but I seem to recall that Fiero front hubs had the same bearings and would fit?? They are 5 x 100 (common these days) and have vented rotors already. You'd have to make up caliper brackets though.

Bob
 
#10 ·
Fiero 5-Lug Hubs

Since this thread is already ongoing, I "merged" these two topics.

If possible, could folks please have a search through the forum for related threads (such as a search for "hubs") before starting a new thread, and then ask whatever questions you have. Also, please try to post under the approriate heading, rather than under "General Discussions". It makes housekeeping much easier, and related topics much easier to find.
 
#11 ·
I'm going to a Chassis guy within the next week and taking him my front suspension, to see what he suggests. I wonder though if a Camaro front hub and spindle assembly might fill the bill. I'll keep you all posted on any progress.
 
#13 ·
5 lugs

How do we track down the owner to get details of the swap.
I had a problem when I bought my GT 250 miles from home, blew all 4 tires on the highway.
Ended up making it home on 3 different wheels and 4 different tire brands.
May be convenient to have a more common wheel.
 
#14 ·
5-lug 70 GT Spyder

Ask and you shall receive. I custom machined my hubs to accept a 5x114 lug pattern. As Far as Chevy 5 Bolt it is I believe 5 on 5. I think this would be too large of a bolt pattern to use. The rear axels werew easy to me to convert, the problem rises in the front hubs. Everything so far is running smooth, but I am in the design process of a new front hub, that I think I could make to change my pattern on the hubs if I wanted to use different bolt patterns. I think a 5x100 bolt pattern would be the easiest to accomplish on the wheel flanges. Still working on other ideas. I really do not wish to build these for anyone do to the time and effort to put into them. If you don't mind spacers and front wheel offsets, they can be used to change bolt pattern. May give you more selection of wheels. I think the front wheel drive wheels are growing on me as the more I am seeing on the GTs.
Keith Lundholm
Tennessee Opel Club
 
#15 ·
5-bolt Hubs - GT Front Suspension

I've investigated the Net and found only one custom producer of a 5-bolt hub for the stock GT front suspension - $300... Isn't there a cheaper way? Perhaps a later Opel model had 5-bolt hubs with the same hub dimensions.
 
#21 ·
Fiero disks

OK Guys,

I picked up a pair of Fiero front disks. Here is some of the information. The bearings DO match, AND the bearing spacing is exactly the same. The inner bearing seal even fits. Now, to the differences. The wheel mount surface is .360" wider relative to the bearings. The disk offset from the wheel surface is 2.41" on the stock GT and on the Fiero it is 1.18". So this places the disk farther out relative to the bearings.
The stock disk diameter is about 238mm or 9.375".
The Fiero disk diameter is about 246mm or 9.69".
The Fiero disk is also thicker at 11mm or .440"
Obviously either different calipers will have to be used, or a mounting adapter will have to be made. I will post when I have worked out what I use.

Swiss
 
#23 ·
not really

I'm not real comfortable with the way most of the Fiero "performance" aftermarket brake kits are set-up. Most of them cut the hub portion of the Fiero brake rotor (they are one piece) from the rest of the rotor and then attach a rotor to it. Unfortunatly the cutting doesn't leave a very thick flange for the lug studs and it gives me the heeby-jeebies.

On the Opel, there may be a better way, but I'm not sure who you would get to make it for you. The difference in offset for the Fiero brake rotors as compared to Opel ones is right @1.25" If the rotor were cut down to 8" or so in diameter, then drilled with a 8x7.0" bolt pattern, regular $35 12.5x1.25" stock car rotors could be bolted to the Fiero hub in almost exactly the right position for the Opel caliper. Unfortunatly the Opel caliper won't fit those rotors, so aftermarket calipers would need to be adapted (or possibly stock GM calipers from larger cars using a modified set of the plates normally welded to rear axles at $12 each) While I think this would work great, and is my current plan (I have all the parts waiting on finding a machine shop) the liability involved with brakes makes most machinists a bit squeamish.

As a result, and as more of an stop gap, I'm going to have some 3/4" aluminum disks made up with the center hole and inner bolt pattern for the back of the stock Opel hub and an outer ring of 8 tapped holes for the stock car rotors. This will allow me to get everything set-up and fabricated, and I won't have to tell the machinist he is working on a brake part, which should relieve him of all liability. Then when I get a lathe of my own (hopefully this fall) I'll cut down the Fiero hubs myself to convert to 5-lug wheels.
 
#24 ·
I posted the link below. It's a conversion using Camaro/Chevelle spindles. I haven't had time to contact Jim Meyers. The idea looks simple if you can get past using different ball joints. Note that not all these (Chevelle) spindles are created equal, some use drums and others have rotors. I was also wondering if Mustang II spindles could be used. Meyer probably knows that answer too.

My knee-jerk thought is changing ball joints is easier than boogering up a bunch of parts to make a conversion work with Opel spindles. Esp. since brakes are involved and Chevy replacement parts are easy to get. Whatever is done will be serviced in the future.

http://www.opelgt.com/forums/showthread.php?threadid=2182
 
#25 ·
lookign at the brake upgrade pictures it loks like they are using new hub but i know people that do the c4 corvette brake upgrade to the front of 3rd gen camaro and t requires cutting off the rotor and they havent had any problems and they race all the time and are hard on their brakes

another thing that should make this easier is the fact that the rotor sits 1.25 out from the stock rotor which will make adapting calipers a little easier
 
#26 ·
i think im am going to spring for this upgrade with the fiero stuff
i was reading all day about the fbody upgrades by making hubs out of rotors for c4 vette stuff and i found a cheap easy upgrade for the fiero stuff doing the same thign and using berretta parts rotors are the same size and stuff but are vented so they are better and parts are cheap for all the parts less machine work it will cost less than $150 and there are more options for stuff out there for the fiero stuff rather than the 320i upgrade not to mention easier to find wheels
 
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