McLaren replica build base on a Manta

Ox, I regard safety as a primary consideration when working alone. Bet that will NEVER happen again. Fortunately all is okay, glad to learn that you were not injured.
 
Ox,

I've enjoyed your build thread using the Manta Mirage as a base. Many years ago I had an exciting ride in a Manta and seriously considered buying one. Recently, I tried to purchase a Manta. Gave up on that and now I'm in the planning process to build a M8B from scratch.

Some questions on your build. You fabricated rear uprights/knuckles, what hubs will you be using in these uprights? Corvette C4? Are you using a Corvair transaxle or some other type? What type axles will you be using?

I'm planning to use a Toronado transaxle with either stock Tornado uprights/knuckles and axles or fabricated ones. Apparently, the Tornado axles allow for some "plunge"( change in length) to improve handling.

I have some info on the Manta if you need it.

Best regards,

CJR
 

Terry Oxandale

Skinny Man
Supporter
Hi Charles! Welcome to the site. This site is a fabricator's dreamsite - practical and exotic all blended nicely. The uprights for the rear are fabricated. A little heavier that needed (9 kg), but nearly bullet proof. The hubs that bolt up to them are some McKenzie's micro-stubs (dune racing parts) using 930 spindles joined up to a GM wheel pattern. I believe the bolt pattern is the old S10 truck pattern on the bearing retainer.

The transaxle in in limbo right know. I'm made all the plans, and aquired all the parts for a 930 transaxle application, but recently came across a reasonably priced 016 that I'd rather use. The only problem is that nobody makes an adapter plate for the LS series motor. So I've got to decide now whether to go LS/930, or SBF/016. The main reason for this conundrum is the shifter rod on the 930 poking out (too far) at the very rear of the transaxle. So even though the 930 is stronger, the logistics of it's fitment are another issue. I weighed the 930 last night and it came in at an even 100 lbs, which was a lot lighter than I expected. I imagine the Toranado transaxle is going to be significantly heavier.
In answering your last question, the axles will be 930 axles. They will provide the plunge needed, and are easy to replace and/or change length.

This weekend I finally did a corner-weighing session with the car sitting on a complete suspension (sitting on the rotors, but with no wheels), and it came out to 222 lbs on each front corner, and 207 lbs on each rear corner. This was with a pretty much complete chassis, but with no gas tanks, body, or drivetrain. So it looks like I am still on target for a 2000-2001 lb net weight.

Any information about the Mirage would be appreaciated.





You're probably wondering why all the 3/4" square bracing on the radiator duct. I plan on using the front of the inlet as a jack-point and felt it needed a lot more support than the sheet box could provide.



 
Charles, the GM 425 transmission is REALLY heavy and will present some difficulties.
The engine is offset to the right because the transmission is positioned along side the engine with the differential mounted directly to the end of the transmission. This places the axles midpoint of the engine with one of them passing through the oil pan. This engine/transmission combination places more weight behind the rear axle line than in front of it. The engine can be moved forward by adding an extension between the engine and the bellhousing or the entire drivetrain can be rotated 180 degrees and the differential flipped over and an extension installed between it and the transmission. None of this is easy or inexpensive to accomplish.

Ox, looking great! lots of progress, keep the pic's coming. Me thinks the 930 will be easier/stronger/more reliable for you. Still looking for that part we discussed.....
Has disappeared into the mist...

Jack
 

Terry Oxandale

Skinny Man
Supporter
Thanks Jack. Don't look too hard though, I found a steel OEM piece relatively cheap, and it's sitting on the shaft. It will do for now. Thanks for all your help, advice, and motivation.

ox
 
No thanks necessary! You are showing exceptional fabrication techniques as your build is progressing. I really STUDY the photo's and have learned from you already so THANK YOU!

jack..
 
Ox & Jack,

Thanks for the responses. I appreciate them! Ox: I've got a Manta manual, so let me know what info you need and I'll get it to you.

Jack: I know the TH425 is heavy but strong. After my Manta ride, I had a long discussion with the owner about some problems he was having with his Corvair transaxle. He had a FI Chevy 350 putting out about 400+ HP. Everytime he stepped on it, the Corvair output shaft broke. At the time, there was some Co. in CA making a high strength shaft. But even with that, the Corvair transaxle was fragile.

Best regards,

Charles
 

Terry Oxandale

Skinny Man
Supporter
My other hobby:


This was an accidental photo of an 82" arc to my 20 ton press frame:



Needless to say, I've learned my lesson and unplugged every valued house-hold electonic device prior to fire-up on Halloween night. 500kV plays havoc with house wiring, and there was plenty of contact through the ceiling drywall.





Yes, electricity will arc from a wheel, across the sidewall, to the concrete floor without damaging the solid-state ignition module.
 
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Hi Terry, ......you seem to have a little of the Mad Professor in you but it looks like something to keep the nabours on the toes.

I have to agree with Molleur, go for the 930 trans as the thought of a SBF in a McLaren based car is sacrelige, No dissrespect to the Ford product, but they should be in GT40s and Mclarens should have Chevys,

I'm impressed with your progress on your Chassis and your suspension, Its come along way from the VW front end you started with and the result is a credit to you, Keep up the good work.

Cheers Leonmac
 
Just a quick Question, the 9kg for the rear up right, is that including the drive hub, CV etc or is just the upright with nothing inside it. Leonmac
 
Terry,

Since you have already done research, you probably know this already.
In any case...I spoke with a fellow many months ago in Dallas who at the time was making adapters to mate LS engines to the 016 trans. So at least at one time someone was making these parts.

BTW, I'm not trying to steer you to the 016 trans. I've broken enough enough marginal transaxles(like Corvair, 901s, and 915s) with midengine V8s to know that you'd be much better off with a 930 or stronger trans.

Jack
 

Terry Oxandale

Skinny Man
Supporter
Just a quick Question, the 9kg for the rear up right, is that including the drive hub, CV etc or is just the upright with nothing inside it. Leonmac
The 9kg is bare, plus the long bolts. I'm going to lighten it a bit where the support is excessive, but it won't be much. With the heavier than required build philosophy (I always overbuild for the street), I've probably added 30 "unnecessary" kilos to the whole car. I guess I'm a bit too cautious.

I'm going to use the 930 (since all parts are accounted for except the LS3), but thought I'd look at the 016 as an alternative since it was relatively cheap by "project" standards.

Jack, not Jack M, but Jack D (I could be a rapper),
Can you send me any info on this fellow in Dallas working on the adapter?
 
Terry,

I had the fellow in Dallas's phone number in my previous cellphone "contacts" directory. The phone got wet and died and I can't access the numbers on it.

Let me look elsewhere to see if I can find it for you.

(I have two 016s myself : they are so cheap I couldn't help myself).

Jack
 
Hi Terry, I have just looked back over your build and have to ask what happened to the SBC and Transaxle the car appears to have come with, and why wouldn't you be using it and what Make of transaxle was it. Just curious. Cheers Leonmac
 

Terry Oxandale

Skinny Man
Supporter
The OEM drivetrain was a Corvair transaxle with the early generation SBC (iron) engine. Being this will probably be my last major car project, I decided to sell the Corvair transaxle and suspension (it was poorly constructed and more poorly modified) which lacked the strength needed behind a healthy engine. The engine itself would have required as much money to modify it as would be a fairly new OEM LS motor.

Perhaps not using the perfectly good OEM engine (stock) is a mistake that will cost me in the long run, but my vision of this project didn't include a cast-iron block and cast-iron Corvair case with a hermaphrodite rear suspension.
 
Thanks Terry, I hear where your coming from RE: the Corvair trans, from what i've read on here they don't appear to be very strong. The good old small block is a good package and no dissrespect but does keep with the era of the car. I ran a full Iron SBC and with not a great deal of money spent, it was a 2bolt, Eagle rotating assm, Fuellie heads, Roller rockers etc, it was 12:1 comp and I was running it on LPG through twin Imco Mixers on 750 holley throttle plates and it ran 385Kw (500HP) ATRWs at 5500rpm. You will still have to spend a bit of money on your stock LS engine to get that. That being said I also can see why you would want an alloy engine and the drivability of modern EFI. I think no matter what you choose you will end up with a great car, I'm just a sucker for the old school stuff.

Cheers Leonmac
 

Terry Oxandale

Skinny Man
Supporter
I appreciate the old-school stuff too. If I was to go iron, then the BBC would be my choice since that goes along with this "old school" project. I still have a full weber set-up that (who knows) may go on top of the LS if I can find a manifold for it. The 8-stack is going to be really hard to leave on the shelf, and it's going to take a lot of discipline to leave it up there.
 
Hells teeth Terry!! If you have a set of Webers that would have settled it for me!! Iron SBC with alloy heads, Darts or Brodix, Steel crank, H Beams and good Pistons, cam and Valve train, You won't be sorry. I wouldn't go BBC as the M6GT which is basicaly what your replicating only came in SB and the Genuine one that Bruce McLaren used as a road car and Prototype was fitted with a pretty stock LT1, it didn't even have headers to start with.
I have to say I really enjoy your build log and will wait with antisapation at your final choice and if you go LS, you have to see if you can get that 8 stack on there some how, that would be COOL. Cheers Mate
 
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