BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6497 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: MGB Roadmaster
The Jag hubs don't have a centering boss so if we use untapered wheels we'll have to put in seat inserts. I need to do this with mine also so I'll probably set up to machine some seats. That'd be about 40 pieces so it'll take a little time but not too bad all at once. I'll have to come up with the right sized counterbore tool though. Carl, do those 15 x 10's have a 4-1/2" backspacing by any chance?
Jim |
V6 Midget Bill Young Kansas City, MO (1337 posts) Registered: 10/23/2007 09:23AM Main British Car: '73 MG Midget V6 , '59 MGA I6 2.8 GM, 4.0 Jeep |
Re: MGB Roadmaster
Jim, if the wheels use a shouldered lug nut lilke most older style alloy wheels as long as the shank of the lugs is a good snug fit in the wheel bores I've never had any problem with centering the wheels. Either way you're relying on the accuracy of the lug studs to locate the wheel. The 113X7 Americans I run on the Midget don't index on the Midget hubs or rear axles and I've had no problems with any balance issues or vibration. I'd use caution machining any wheels in the lug area not to remove any of the design strength in this area to fit tapered inserts.
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mgb260 Jim Nichols Sequim,WA (2479 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: MGB Roadmaster
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mgb260 Jim Nichols Sequim,WA (2479 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: MGB Roadmaster
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BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6497 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: MGB Roadmaster
Nice find on the upright brackets Jim N, and the diagonal anti-torque braces on the back are a nice touch as well. That one is clearly a top end system as evidenced by the custom uprights. Looks like they were attempting to use the shocks as a replacement for the radius rods but it seems that solution would be less than ideal.
I did some more checking this morning and first things first, the Jag hub does have a pilot boss for the wheel. At 2.900" it is larger than the Chevy boss at 2.781" but could easily be turned to match, meaning that we should be able to use just about any GM hub-centric or lug centric wheel. The Jag uprights raise a whole new issue in terms of backspacing though which came to light when I looked at Jim N's brackets. Also, Bill you are absolutely right about machining the wheel centers. On the Weld wheels IIRC they have two 1/2" sections mated together which if so might not allow the necessary machining. My Centerlines may be the same. As for the discussion of whether hub centric wheels can be run on lug centric hubs, I can only say that is the setup on my car and I've never gotten rid of the wobbles entirely. 'Course it could be the tires. There have been complaints about them. The issue with the uprights is twofold. First, a top link is going to be difficult to design due to the need to go inside the frame rail to allow maximum space for rubber in the wheelwell. Otherwise the link will take up at least 1" of tire space with a conventional design and materials, and attaching it inside the frame rail is likely to severely limit wheel travel and lowering of the body. So we need to make a decision here: Do we move the wheels out and flare the fenders similar to the flares on my car to get the needed tire space? Or do we forgo the suspension top link, beef up the LCA, go back to timken LCA bearings instead of Delrin and hope for the best? I had some light outside wheel rub with 1" spacers and maximum lowering and with the spacers gone have about 1-1/2" averaged clearance to the shock bolt heads on the inside, so possibly 2" of clearance that I am not using with these tires. (10.37" section width, 8.35" tread) so the potential is at least there for 12" wide x 27" tall tires maximum, or 11" wide with a top suspension link. Adding compexity to this decision is the configuration of the uprights themselves. If we use a conventional backspacing of 3 to 5 inches the bell of the upright is the limiting factor in upward suspension travel. It may be possible to trim it to get more upwards movement. But there's another possibility. I have some old Probe GT wheels which are 16 x 7 with about a 5" backspace. I set a hub and upright in the wheel to see how that works out: As you can see, a careful construction of the LCA could allow use of a deep backspacing, moving the upright further inside the wheel and thus moving the bell closer to clearing the frame rail. From this it looks like the new FWD wheels could be very useful. Something like a 17 x 10 with a 7" backspacing would probably let us clear the frame and leave room for a robust LCA attachment. Obviously the fronts would have to be different. But since it's generally easier to find wheels in pairs this may not be a bad thing. We could stagger the diameter and width and use the Omni flares on the front. Neutral handling can be restored with a stiffer front bar and staggered tire pressure so I'm not that concerned about the handling changes this would cause. Guys, it looks like we are moving ever closer to the drawing that we need for our club logo! Wonder if there's a way to run open headers out through a set of ventiports? Jim |
BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6497 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: MGB Roadmaster
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BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6497 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: MGB Roadmaster
I missed it anyway, oh well. Cast wheels obviously huh? That's what I meant about the wheels sticking out past the tires. I'm seeing a lot of damaged rims.
Looks like the 255/40-17's are real common, and 265 and 275's are not exactly scarce. Apparently the 50 series 14's and 15's were dropped in favor of them. Go figure. Of all the 50 series tires that used to be made, there's nothing much anymore bigger than a 225 that I can find, with one notable exception: the 295/50-15 (LR50-15). Now why is that? A Corvette tire perhaps? That'd be my bet. And probably after tires are no longer used those tires for old Corvettes will still be available. I found the page for calculating tire dimensions, and that size works out to a 26.6" diameter and 11.6" overall width. My handy dandy chart for BFG TA's (who still make them) shows a rim of 9-11" and a design rim of 8" wide, overall dia of 26.21" and a tread width of 9.4" meaning that they could probably be fit into the rear wheelwells of my roadster, or if we made similar flares on the Roadmaster they could work there also. Interestingly enough, the 295/35-18 tires for the Z06 Vette work out to very nearly the same dimensions and the front tires are 265/40-17's which might work on the front. The modern Vette wheels also have some serious backspacing, which could be real helpful on the rear, but only if we went to the 17 or 18" wheels. Which gets us back to 35 or 40 series tires and rims wider than the tread, and curb damage. But, a typical offset for these wheels may be the 57mm I saw on a 9.5" wide rim (rear). That works out to a 2-1/4" offset, or a 7" backspacing which is pretty ideal for our Jag IRS. If this is typical for Corvette then it gives us a ready source of wheels and rubber provided we can stuff it under the car. It also matches the rim to the tread width and gives us a 1" sidewall bulge to protect the rim. Although I wasn't really planning to do another set of rear flares I can see where this would be a real advantage. On the front things are a bit different. We need a wheel with a 3 to 3-1/2" backspacing in order to clear the inside and we are more limited on the diameter. We may be able to use as large a diameter as we can in the rear but even with the Omni flares we can't go all that much wider, and as we increase the diameter the offset to the inside has to decrease to keep from rubbing the footwell (going from memory here, corrections encouraged.) This all means the wheels are likely to not match if we go this route, unless we make up a pair of big honkin' billet spacers about 3" thick. Can be done, theoretically no worse loading on the spindle. Any fans of that approach here? So you see, all of this stuff just gets to running around inside my head to the point where I have difficulty doing anything at all. Much easier for me if someone just says, "Here, this is what you have to work with. See if you can find a way to make it happen." Anybody got an old set of Corvette wheels lying about the place? Bill Guzman are you out there? Well, it's a thought anyway. Jim |
BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6497 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: MGB Roadmaster
What about these wheels?
[cgi.ebay.ca] A little wide for the back maybe. Any comments? Jim Maybe we ought to just put N50 wrinklewalls on it ;-) |
Moderator Curtis Jacobson Portland Oregon (4593 posts) Registered: 10/12/2007 02:16AM Main British Car: 71 MGBGT, Buick 215 |
Re: MGB Roadmaster
I'll play devil's advocate for a minute:
I don't understand the appeal of huge wheels and tires for a little British sports car. The trend towards extra big tires on little cars is about as silly as fashion trends get, and will surely run its course and reverse sooner or later. ("Low-riders" were popular just a few years ago. Seen one lately?) The MGB GT V8 is only a 2400lb car - even with a big block - and it only needs so much contact area to stick like glue. Unless you're going to fill the wheels with huge brakes, I don't see any point in driving up the moment-of-inertia (i.e. "flywheel effect") so high. Instead, why not pick the cheapest "just big enough" new tires you can find with really, really sticky compound? (Also, I would expect that keeping scrub radius as small as feasible should help with steering-effort/"returnability".) Consider the Falken Azenis RT-615, which is a nice sticky tire for autocrossing and other sporting uses. The 255/40-17 version weighes a whopping tremendous 27.5 pounds, and it's recommended for use with a 9" wide rim. The same tire in a far more sensible 205/40-16, only weighes 18.2 pounds, and is recommended for use on a 7.5" rim. (Unsprung weight isn't the only issue - the average distance of weight from the axis of rotation is the other key factor to moment of inertia. Radius squared, right?) IMHO, the smaller tire will BE quicker and will feel quicker. It'll be quicker to get up to operating temperature. It'll certainly be easier to package, and it'll save about $168/set too every time they need replacement. (The cost difference is $80 vs. $122 per tire, before installation.) --- Rim protection has come up as an issue in this discussion. If this is a big issue, some of the newer tires are advertised as having a special rim-protecting bulge molded into the rubber to help avoid curb scuffing. |
Citron Stephen DeGroat Lugoff, SC (367 posts) Registered: 10/23/2007 09:43PM Main British Car: 1970 MGBGT V6, 7004R, AC, matching trailer 3.1 liter |
Re: MGB Roadmaster
I agree with Curtis. I am not a fan of big rims.
Probably not what you want, but I have a set of 85 Jag XJ6 wheels in good condition if we need them. If we don't, then I will keep them for my Jag. Steve |
V6 Midget Bill Young Kansas City, MO (1337 posts) Registered: 10/23/2007 09:23AM Main British Car: '73 MG Midget V6 , '59 MGA I6 2.8 GM, 4.0 Jeep |
Re: MGB Roadmaster
Steven, I agree with you for the most part and am not a fan of the modern thin sidewall rubber bands on the 17" or larger wheels. They just don't have the right "look" for the MG. I think we could do pretty well with the Jag wheels and something like a 235 50 15. We're not drag racing so having steam roller tires out back isn't necessary, just something that will give enough side bite and handle well. They would enable us to find both reasonably priced wheels and tires for the project and probably be available for years to come.
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rficalora Rob Ficalora Willis, TX (2764 posts) Registered: 10/24/2007 02:46PM Main British Car: '76 MGB w/CB front, Sebring rear, early metal dash Ford 302 |
Re: MGB Roadmaster
BlownMGB-V8 Wrote:
------------------------------------------------------- > Much easier for me if someone just says, "Here, this is what you > have to work with. See if you can find a way to > make it happen." I spent a lot of time on this delima this past summer. 15" tires in widths we'd like -- especially for the rear -- are hard to find & seem to be getting harder. 16" & 17" tires with good widths and even reasonable diamters are relatively easy to find. But, 16 & especially 17" wheels are hard to find w/o very deep backspacing (very positive offsets). That can be ok for the rear where you have more control over the rear end width, but becomes a problem for the front. And, the wheel/tire combinations are generally way heavier. Given we're on a Budget (capital B intended :) ), I'd suggest the first order of business is finding either 15" or 16" wheels that'll work. -- If you/we find 15" wheels with 6-7" wide front & 7-8" wide rear, go with either 205/55/15 or 215/50/15 front & 225/50/15 rear. -- If 16" wheels with reasonable offsets & 6-7" wide front/8-9" wide rear can be found -- which would be my 1st choice if looking again, then use 205/50/16 front & 245/45/16 (or 225/50/16) rear. In either case you want something with close to 0 offset. A little negative offset on the front helps, but spacers can make up for a bit of positive offset. The rear doesn't matter as much as long as it's not so positive that the control arms cause a problem. Once you find the wheels, you can close on tires and with that, the rear end width & whether you'll need spacers on the front -- which I don't think would need to be more than 2" with any of those combinations. If, however, spacers are needed, you want to do the type that bolt to the hubs & then have their own studs that bolt to the wheels for anything in the range we're talking. I know it's frustrating to have to hold off working the IRS till you have the wheels/tires, but it's really the best way. Hey, you asked for someone to say here's what you have to work with... now go make it happen :) Rob Edited 1 time(s). Last edit at 03/03/2008 02:03PM by rficalora. |
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BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6497 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: MGB Roadmaster
So then, no wrinklewalls? Pity. ;-)
The Mig welder was delivered today. Thanks Bill Y, it arrived relatively unscathed (or about as scatheless as UPS gets I suppose) and was soon put in working order. The feed was erratic but on pulling the drive wheel I found the shaft key lying below it and that was promptly remedied. All looks fine so far. Bill I apologize for not getting the check out sooner, it was deposited in the mail first thing this morning so it should be there in a day or two. So we're ready to get on with the body work. Incidentally, I sent the Vendor Presentation (VP) via email to Mike at T&A and plan to call him tomorrow. If I get a chance I'll also make some calls on wheels and tires. Maybe I can get ahold of someone at Weld and Goodyear. Guys, just let me mention that anyone who wants to approach a potential sponsor is welcome to take the VP and do so. Nothing says it has to be me that makes the contact. If you can't get ahold of me to get a copy, Curtis, Carl, and Steve have copies also. So I guess XJ6 wheels are 15"? If I understand the consensus so far, we're mainly looking for 15 or 16" wheels, 16 preferred. Then something like a 7" front and 8" rear width, no offset on the front, maximum backspace on the rear, does that sound about right? No stagger of diameter between front and rear? That sounds OK to me, I like 50 series tires on the MG personally but they're being obsoleted. My theory is that with gas prices going up they're replacing the older and less expensive tires with new ones that are more profitable, and the old ones will all either disappear or become scarce and therefore expensive and profitable. So while they're cheaper right now, by the time we wear them out there may not be any difference. Anyway I figure to start with if we don't have a sponsor we can look for a deal on ebay, especially for the rears which may not last long anyway. I really do appreciate the input. I don't want to be on the phone with Weld saying something like, "Uh well, maybe a 15" wheel would be good, or 16. But then a 17 might work too or even 18 maybe. Width? Oh somewhere between 6 and 10" I think. I'm not sure about the offset. But I do know the lug pattern.... Obviously that'd get us nowhere real fast. If anyone has some good contact info send it along and that'll be my first call. Jim |
Citron Stephen DeGroat Lugoff, SC (367 posts) Registered: 10/23/2007 09:43PM Main British Car: 1970 MGBGT V6, 7004R, AC, matching trailer 3.1 liter |
Re: MGB Roadmaster
Jim,
I have been e-mailing with Dale. He will have the 455 ready for me to pick up in Danville the last of April. Let me know if you want the Jag wheels. They are 15's. Don't know back space or width. They are standard 85 XJ6 wheels. They are in the attic of the shop and have I beleive very used Dunlops on them. If you are interested, I will dig them out and get the tires removed. Steve |
MGBV8 Carl Floyd Kingsport, TN (4556 posts) Registered: 10/23/2007 11:32PM Main British Car: 1979 MGB Buick 215 |
Re: MGB Roadmaster
"The MGB GT V8 is only a 2400lb car - even with a big block - and it only needs so much contact area to stick like glue. Unless you're going to fill the wheels with huge brakes, I don't see any point in driving up the moment-of-inertia (i.e. "flywheel effect") so high. Instead, why not pick the cheapest "just big enough" new tires you can find with really, really sticky compound? (Also, I would expect that keeping scrub radius as small as feasible should help with steering-effort/"returnability".)"
I agree, Curtis, especially for my car. ;) This car is looking at hooking up 500 ft/lbs of torque. I haven't noticed that the big, fat 18-19" tires hurting Porsche any. I see the 16" wheels/tires as a transition from the 15" to the 17". I think they will go away faster than the 15s. 17s are here to stay, but are more costly than the 15s. Rob, You'd have hard time convincing me to bolt a 2" spacer on the front hub of my car. I'd rather use what will reasonable fit & live with it. That said, I have no problem with running different size wheels and/or diameter stagger. Jim, I think the deal with the 295/50-15s being still available is that back in the day before the Pro Street movement when someone wanted impressive meats on their muscle car, like a 1st gen, Camaro, they used those N50s. Later, big radial came along (along with better handling). The BFG T/A 295/50-15 was the biggest radial made for street rodders for a long time. My Camaro currently has BFG Euro T/A 305/50-15s. I don't think are made any more. Any way there are still a lot of muscle cars (including Cobras) using the 295/50-15. I think it will continue to be available for a long time (I hope). "If you/we find 15" wheels with 6-7" wide front & 7-8" wide rear, go with either 205/55/15 or 215/50/15 front & 225/50/15 rear." I'm with Rob. |
BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6497 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: MGB Roadmaster
I just got off the phone with Greg Smith at Weld Wheels. He is very informed about the MGB V8 swaps, enough so that I wanted to ask about his background, but I stuck to the matter at hand instead. Greg said that the Pro Star is really not made for the kind of cornering forces this car will see, but it turns out that they will be introducing a wheel called the G Force that sounds ideal for us and it is due to premier in June 2009, right about the time we expect to get our project finished. These are the kind of coincidences that you just have to love.
He validated some of Carl's comments above, in that first off, Weld does not make a 16" wheel. The G-Force will be available in 15 and 17", and in a wide enough variety of back-spacings to easily accommodate our needs. I sent him the presentation package and invited him to visit this thread. Let's be sure to welcome him in a most cordial manner. There were no promises made or asked for, but we'll get to that once he knows us a little better. I also talked to Mike at TA Performance this morning and sent him the presentation as well. He had some rather interesting news. It turns out that he has decided to look into making a head to fit the Rover. Now this came about because of an Aussie who contacted him and pointed out that with a bit of cut-n-paste the V6 head could be turned into a V8 head, and as we know, that means a head that will fit the 215, 300, and 340 as well. It sounds like he is really wanting to do this, and I've got to tell you, the SBB 350 guys are just going to go absolutely nuts when they hear about this one! (But with different manifolds and bushings for the cam bearings they'll be able to use these heads too so they shouldn't feel too bad.) OK so that's off track a little but I thought you guys would want to know. Sharing ports and valves with their aluminum V6 heads we're talking some serious go fast parts here and a major boost for the BOP/Rover/SBB to MGB swappers. He'll have a better idea of how he might be able to help us after he sees the presentation. I will continue to follow up on both of these contacts until we know if we can count on them, or if we should move on. In the meantime I soon plan to move on to tires, and in that vein I think we have more to discuss. If we are able to get the G-Force wheels, my vote is for the 17's at least on the rear. What we run on the front doesn't matter to me anywhere near as much. In fact, a 15/17 stagger with about the same sidewall height at both ends is going to make a visually appealing combination, and as I said earlier, we can flare enough to accommodate wide and tall rubber in the back. At this point I'd worry a bit less about cost as I'm confident that if Weld comes on board we can find a tire maker who will also. So we should be able to handle up to a 5" sidewall with the stagger. What does that allow us in tire sizes and what does it require in rim widths? (Remember we can use up to about a 7" backspacing. Can you guys help me out with this? Jim |