Manta Front Suspension Swap into a GT

[jeff denton]

While we are on the topic of front suspension and a mustang II conversion has popped up, and given that the GT design is kind of lacking what the Manta has, may we open some minds to consider the possibilities of putting a Manta suspension under a GT? Now, I have never been close enough to a Manta to see how it works, there just is no such thing as one around here that I know of. Sure I suspect such an undertaking requires fabrication skills and there won't be a kit in the JC Whitney catalog to do this for under twenty dollars, but, logistically is this feasible or should I switch to a brand of beer with less alcohol content?
If you wonder why I ask this, just think how tune-able a Manta coil spring front end might be compared to that WEIRD transverse leaf spring the GTs have. Our racing rules don't mention any adherence to factory stock other than saying "may use any steel spring, mounted in stock position with stock mounting brackets. Front springs may be heated or bent, lowering blocks are approved." It probably never dawned on anyone in this class to use the front suspension out of a different car, otherwise it would have been done and a rule written to forbid it.
Does the whole Manta front suspension "drop out" of the chassis like a GT, and how close would it be to "fitting up" to the GT chassis?
Food for thought, argument, speculation, inquisitive minds want to know and our club has people who would have the answer!

[baz]

jeff this is what you would start with
no problem in your tube frame

[jeff denton]

Wow, BAZ, you're quick!! I'm seeing a drop out main suspension crossmember and some rearward brackets. What, then, steers it?
Looks like there are two bolts that attach the crossmember to the frame, I wonder how far apart these two bolts are? And doesn't the Manta have a bit wider track than the GT? This might be way awesome...
Isn't it kind of early in GB? What time do you get up on Sunday mornings, anyhow?

[RallyBob]

Jeff, the Manta uses rack-and-pinion steering as well, front-mounted like the GT. It is however solidly bolted to the crossmember, no rubber bushings are used. Yes, the track is wider, it's listed as 52.4" front compared to the GT's 49.1" (Keep in mind the GT wheels had 4" backspace, the Manta had 4.25" backspace, both with 5" rims). However the rack and pinion is actually shorter between the inner tie rods, due to the longer a-arms. In stock form, the front crossmember is rubber isolation-mounted, but this is easily changed.

Bob

[baz]

rack is similer to gt and the track is a bit wider but i dont have the numbers to hand
and its only 11.27 so early for me as ive been awake for 2 days as im full of steroids from my chemo and cant sleep

[RallyBob]

Originally Posted by baz .....ive been awake for 2 days as im full of steroids from my chemo and cant sleep

Time to hit the gym then Baz! Make them steroids work for you, and do something with your sleepness nights!

Jesting aside, I hope the treatments are going well. Cheers...

[baz]

i thought it was coming back bob but it turns out i now have gout and that was giving me the trouble this last month
im feeling that well with 1 treatment to go in 3 weeks that im coming over to FL and GA between 10th and 24th of jan for a holiday

[jeff denton]

Yes, BAZ, please do whatever it takes to get well, we love you and need you. You are a brother to all of us here!!
Can anybody with a Manta shell and a tape measure tell me simply how far apart the bolts are? Thank you!
Wow, I'll be in Georgia for school the week of Dec. 7, wish our paths could cross!

[RallyBob]

Originally Posted by jeff denton Can anybody with a Manta shell and a tape measure tell me simply how far apart the bolts are?

Sorry, which bolts? I'm about 20 feet away from a Manta right now, without an engine. All dimensions are fairly accessible at this time.

Bob

[baz]

top mounts at a guess

[RallyBob]

Originally Posted by baz top mounts at a guess

27-3/8" center to center then.

HTH!

[jeff denton]

Awesome. BAZ's picture calls them "crossmember to body shell mounting", I'm just curious how sanitary this crossmember could bolt into my frame rails, which currently accept the GT crossmember in rather stock fashion, two bolts per side. Probably not a big deal, I do have some basic fab skills and a torch and a plasma cutter and a sawzall and a grinder and a welder and a...:
Thanks, Bob. I just measured Parts GT's mounting bolt spacing, it is 23". Now, had I a Parts Manta I'd be firing up that torch right now!

[baz]

jeff if no manta's about look out for a jenson healey gt has the same set up front and rear with a vauxhall 4 or 5 speed and a lotus engine they sold nearly all of them in the states

[RallyBob]

Originally Posted by jeff denton I'm just curious how sanitary this crossmember could bolt into my frame rails, which currently accept the GT crossmember in rather stock fashion, two bolts per side. Probably not a big deal, I do have some basic fab skills and a torch and a plasma cutter and a sawzall and a grinder and a welder and a...

You could certainly knock at least 1/2"-5/8" from the top of the Manta crossmember to shorten it a bit before worrying about the upper a-arms getting too close to the frame.

[jeff denton]

Thank you BAZ and Bob. I'm gonna start a search for a scrap Manta and think on this some more. We may be on to something...
I'm not sure what a Jensen Healy GT is but from the sounds of it, were one available I'd bury Speedway GT and start over...

[kwilford]

These posts kinda hijacked the front suspension rebuild thread, so they in turn got hijacked to their own air space

[Killer Texas GT]

Jeff
The Buick/Opel by Isuzu (Kadett 'C') would be an easier change to get independent front coil suspension on the GT, than attempting to install the Manta suspension. Uwe Klippert has done this to his GT in Germany and it has been TUV(?) approved even. He says that it handles like a go-kart. The Kadett 'C' suspension is only 3/4" wider that that of the GT suspension. And if handles anywhere close to my GT with the Impulse front suspension, it is wicked and is a BA handling go-kart. The Impulse suspension is about 1/2 to 3/4" wider than the Manta's. I am using the shock towers from the B/O by I, with GT shocks, and cut down coils from the Impulse, the B/O by I springs where a little to soft for the way I was set up.
The independent coils on a race car like yours would for sure open up the options on set up and allow you to balance the GT even for the turns. Marty Reimer and I are getting ready to set up his Rotary GT with the B/O by I suspension for road racing in order to strenghen his set up, due to the lower control arm set up and the way the cross member is attached to the car, also the sway bar is in the forward position allowing for more possible options for a dia. increase. I have some pictures that Uwe sent me and some of his detail drawings that I have on file( but am still looking for the pictures, and as soon as I can find them I will post them).
rk

[jeff denton]

Thanks for the tip! I'll have to figure out what the heck a Buick Opel Isuzu Kadett C is now. As long as it's pre-1985 there are no printed rules against using it, as far as I can tell. Since it has Opel amongst its names it's stock, right?

[oldopelguy]

Heck, if you can go that new maybe a Kadett "D" front end would be easier to find? Got to be a Chevette rusting away out there somewhere.

[jeff denton]

Well, geez, Chevettes are a dime a dozen! Didn't I read once that their spindles and brakes are a popular swap into GTs? So you're thinking that maybe the whole Chevette front suspension would go in, huh? Interesting...
So it would be kind of stock, this "baby vette" with a "che-vette" front end.
Close enough. They are both 'vettes, right?
Thanks, Stephen!!

[Killer Texas GT]

Originally Posted by jeff denton Thanks for the tip! I'll have to figure out what the heck a Buick Opel Isuzu Kadett C is now. As long as it's pre-1985 there are no printed rules against using it, as far as I can tell. Since it has Opel amongst its names it's stock, right?

The Buick Opel by Isuzu is 76 (for sure) and I believe 78, then they went to Imark which was front wheel drive.

[asdasc]

I had also heard that the rear end of a Pontiac Fiero was actually the front end of a Chevette in the earlier years. They simply turned it front to back and fixed all the steering parts to the frame. That made it very adjustable.

[oldopelguy]

Originally Posted by asdasc I had also heard that the rear end of a Pontiac Fiero was actually the front end of a Chevette in the earlier years. They simply turned it front to back and fixed all the steering parts to the frame. That made it very adjustable.

The front end of the Fiero is basicly Chevette, the rear of the Fiero is a Citation front end. Because the Citation suspension used a high off-set FWD-style wheel, though, the moved the wheel mounting surface on the front hubs out 3/4" or so with respect to the bearings and spindles to allow front wheel drive wheels to still have proper geometry. They also swapped over to a 5-lug hub. But, if you take hub, caliper, and caliper mounting bracket as a unit you can swap the Fiero hubs right onto the Opel spindle.

[dryandell]

Are you saying we can rob fiero's for parts to make a cheap conversion to the GM 5-hole pattern? ...and probably have better braking in the process?

[asdasc]

Hi OldOpelGuy,
Thanks for the correction! I have been away from the car stuff for the past 20 years, but used to be REALLY into it. I have the bug again now that my kids are growing up. I am finding that the info is up there, but randomly accessed anymore.
Steve