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74 Opel Manta

Posted by EvanB 
Yellowhammer
John Barnett
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Re: 74 Opel Manta
February 04, 2015 06:38AM
FOk maybe I had too much wine last night... Maybe. drinking smiley

Anyway, lol excuse me for not knowing that " Lincoln Diff " was
Slang for welded diff.. Excuse my ignorance. Lol,. I have had a welded diff ( on a fwd rabbit if that counts ) and
Never heard the term Lincoln- locker... So that's on me.


Anyway, yes........... I am aware that welded duffs work and like most things there
Are opinions on both sides of that

I do not want a welded diff on my manta I think.. Me/mine.. Do what you want and I am not the person to say anybody is wrong about anything..

slow turns on pavement doesn't feel good to me. I have not had a welded rear diff but driven an RX-3 with one briefly and on track and only on track at speed I think it's great and you get used to it pretty easily, but loading, unloading, paddock, and on the street would be horrible and flat out dangerous to me... Just mho.. yRmV!

I would rather
Not do some clutch- type thing because it seems to me ( I try to listen to the learned positions of people who have been there n done that ,
ALL opinions). That in a rally cross or rally situ that the extreme duty would cause me to break it Or be worried about it constantly with new clutch packs Or adjustments or whatever.. Again, just trying to figure out the best app for my project.

So- it would appear that open diff iis not using full potential , welded doffs yes are easier but have there faults and drive ability drawbacks , and option #3 is a super expensive ( too me ) official Opel Motorsports rear diff that likely requires exchange rates, proper install, and big money. Fourth option seems to be The Kaaz/ quaife / ? $1300 range.. I guess for me personally the 1300 Kaaz or gripper or whatever seems to be in the middle of some 300 dolla answer and whatever it is for the apparently hard to find- never priced one for real- Opel Motorsports rear differential,, I would like to know if there is another option that I might not know about... Before I pull the trigger on a solution to my open diff... That is all.



Edited 2 time(s). Last edit at 02/04/2015 06:42AM by Yellowhammer.
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EvanB
Evan Arthur
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Re: 74 Opel Manta
February 04, 2015 11:20AM
I'm planning on (eventually) a Dana 30 from a Volvo for mine. Lots of gearing options and cheap lockers available.

I have a clutch type diff in my Miata for rallycross. It was pretty much open when I got it but I shimmed it up with some pieces cut from beer cans and it is still working great after 3-4 years of abuse behind the turbo engine.
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Yellowhammer
John Barnett
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Re: 74 Opel Manta
February 04, 2015 12:23PM
Quote
EvanB
I'm planning on (eventually) a Dana 30 from a Volvo for mine. Lots of gearing options and cheap lockers available.

I have a clutch type diff in my Miata for rallycross. It was pretty much open when I got it but I shimmed it up with some pieces cut from beer cans and it is still working great after 3-4 years of abuse behind the turbo engine.

spectacular..

Ok, tell me the skinny on the D30/Volvo. Maybe I'm making it harder than it has to be with all this 'keeping it all opel' plan or the 'period-correct' plan..

To be fair to JVL's particular point : yes maybe my plan IS crap..
> * because, like let's say I show up at a stage rally somewhere with this car someday ( which Is what every build except museum pieces are about- how to stand the unexpected fail..)

and so, ok, yay. We are done.. tag legal and lights burning.. and ready for a logbook on car from CARS/RA/NASA/ whoever...
I doubt I'll even worry about FIA cause they would probably laugh me outta tech, but anyway..
_ __ ___ _____ ___ turn the page, Bob Segar, turn it

new plan : So I have some Volvee rear end, or a Chevy rearend, or a Frog rear end off of a dumptruck, or ford axles and chevy diff ? ? =

who really, actually gives a shit except 5 old Opel dudes and hey man, they sure as hell don't care ,

if even there, they are just happy to see a Manta A out burning gas.....and pleased with themselves that they spotted my rear-end swap immediately...
and grin and nod slowly...

> That would be ok too. I've already done a r&p like 5 years ago, a 4.11 or 3.9-ish
I cannot remember the exact gear I've slept since then...
# but it def pepped the car up esp between 2/3. That was when I was on a rare work-on-the-Manta kick. The progress comes in spurts/it comes and goes,

car has spent the better part of a decade inside the back corner of some shop or moved to another hideyy-hole till I can find some extra money or time to get another piece to the puzzle I am trying to put together... Please do it faster than I have managed so far...

Do you have to take opel axles and everything and do the whole rear or just the diff ? How's that for a straight question to chew on.. ?

Cheers, John



Edited 1 time(s). Last edit at 02/04/2015 12:28PM by Yellowhammer.
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Robert Culbertson
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Re: 74 Opel Manta
February 04, 2015 01:20PM
Quote
EvanB
I'm planning on (eventually) a Dana 30 from a Volvo for mine. Lots of gearing options and cheap lockers available.

Just a heads up, not all Volvo differentials are true Dana 30s. The later model 1031 (larger ring gear and reinforced housings) will not take strait drop in Dana 30 parts. These were found on all turbo 240s, and later model (mid 80s-ish) 240s, and all 740s.
The pinions are different, and use different bearings. The ring gears are also bigger in diameter as well.

The carriers will transfer between them with no problem though. There are 2 different sizes as well, above 3.73 and below 3.73.

The Volvo 1030 will take straight Dana 30 parts. Early model 240s only.

Adam crane used a Volvo rear end in the Corolla, but I'm not sure which one and what gearing they used. They have had a few issues with them though.
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EvanB
Evan Arthur
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Re: 74 Opel Manta
February 04, 2015 02:24PM
Good info Robert, I had heard there were some differences but haven't looked into it too much yet.

John: I thought there was a writeup over on OpelGT.com about swapping in the Volvo axle but I can't find it at the moment.
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john vanlandingham
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Re: 74 Opel Manta
February 04, 2015 02:38PM
Quote
Robert Culbertson
. Early model 240s only.

Adam crane used a Volvo rear end in the Corolla, but I'm not sure which one and what gearing they used. They have had a few issues with them though.

All the guys in the PNW since we did the first one back in 1988 have used early "Real Dana" 240 complete axle, Crane, his buddy Dustin, John Reed in Portland, all "real Dana 30 stuff"

That's the whole point...
Crane and Dustin used 5.35 final drive, works good for little motors making no poop.
Reed's was a 4.88 I think,

"Issues"??

Issues? WTF is issues?

PROBLEMS were not related to Dana 30 anything but more like mayhem, savagery, foolishness, hitting stuff, bending shit and carrying on....normal stuff.



John Vanlandingham
Sleezattle, WA, USA

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Robert Culbertson
Robert Culbertson
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Re: 74 Opel Manta
February 04, 2015 03:22PM
Oh, I never said the issues were directly related to the mighty dana 30 smiling smiley

Driving like a savage takes it's toll on equipment. I still like how the panda finished with a ratchet strap holding the axle tubes into the center section. POR!
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Ascona73
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Re: 74 Opel Manta
February 04, 2015 04:07PM
I'm really partial to the Toyota truck axles. They're actually about 10 lbs lighter than an Opel axle when you take the torque tube out of the picture. Cheap LSD's and lockers are available, as well as gearing options from 3.07 - 5.71. Pretty darn strong too. There are a lot of import drag racers in this area with old school Starlets, Corollas, Datsuns, Mazdas and pretty much the 8" Toyota is the prefered diff for cars turning as fast as 9's in the 1/4 mile.

Anyway, the type I prefer are the 1984-1988 2wd truck 8" rear axles. They're 7/8" wider than an Opel axle.



Opel is a 4-letter word...
http://www.flickr.com/photos/10498579@N07/sets/
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Yellowhammer
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Re: 74 Opel Manta
February 04, 2015 05:34PM
ok good stuff.

- cause I obviously cannot speak for Evan or his plans, but for me 200hp is a pipe-dream.

No Turbo, No No2, no blower... just some old re-built carbs/mani-s and a non-outrageous cam, and some headers, pistones, and a knifed crank... no big cheater motor but twice the stock hp is rarely not fun, in anything..


Toyota I can find. Volvo I can find. now we are getting somewhere to a couple reasonable options on hiney gears.

* opelgt.com is a obviously wonderful site,

but I too often have a hard time finding what I want to read up on...

usually what I want is outside the 'show-car Opel GT crowd'...
nothing wrong at all with a cool GT with some cool wheels and a widebody on it..
not my cop o tea, but then a dirty Manta A with Knobbies on it, interior ripped out, and nothing to polish = - that is a pretty fucking small club.. what, 40 years now these cars are..

> and those opelgt.com guys do not suffer fools, Bob can attest to that I would assume...
They can have a thread about windshield wipers go on for a decade. no shit.



lol.



Edited 1 time(s). Last edit at 02/04/2015 05:38PM by Yellowhammer.
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Ascona73
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Re: 74 Opel Manta
February 04, 2015 06:36PM
Quote
Yellowhammer
not my cop o tea, but then a dirty Manta A with Knobbies on it, interior ripped out, and nothing to polish = - that is a pretty fucking small club.. what, 40 years now these cars are..

You are certainly in small company. AFAIK, the only folks entertaining an Opel these days in the US of A for rally use are you (Manta A), me (Ascona A), Mark Bowers (Manta A), Dave Clark (Ascona cool smiley, and the dude who started this thread!

I started like you doing the rallycross and ice racing thing with decent results. Decided to step it up a notch and go stage rallying but money ran out. So I have a stripped, rusty hull sitting there collecting dust in my shop. I have all the suspension/brake stuff done. Got me some fender flares. Some rust repair done. Skid plate done. Got wheels. Got one potential engine/tranny done already (1.9 with about 175 hp and a ZF gearbox), but being an Americanized Canadian I want more now so I'm gonna build a 2.5 litre monster with about 240 hp and a close ratio T9 gearbox.



Opel is a 4-letter word...
http://www.flickr.com/photos/10498579@N07/sets/
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Yellowhammer
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Re: 74 Opel Manta
February 04, 2015 10:25PM
I bought fender flares and they are still in the box from Charles Goin

I decided not to put them on..

I wanted the Group 4 look with some fat Panasports n such.. But couldn't bear to cut perfectly good quarters and wings.

But If I wreck (likely) or smack a tree somewhere... Oh,then it's on like donkey kong.
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Pete
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Re: 74 Opel Manta
February 05, 2015 12:42PM
Quote
Yellowhammer
ok good stuff.

- cause I obviously cannot speak for Evan or his plans, but for me 200hp is a pipe-dream.

No Turbo, No No2, no blower... just some old re-built carbs/mani-s and a non-outrageous cam,

Why? Cams is cams price wise, and I have never met anybody who said they went too wild with the cam.



Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.
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Ascona73
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Re: 74 Opel Manta
February 05, 2015 02:05PM
Quote
Pete
Why? Cams is cams price wise, and I have never met anybody who said they went too wild with the cam.

There is a point of diminishing returns unless you really know what you're doing. Not only in power, but reliability.

The shops with the Chevy mentality (even though Opel is GM) inevitably get it all wrong. Too stiff a spring rate, too much valve lift, too much exhaust duration, blah...blah...

Case in point. A guy was road racing an Opel Manta many years ago, decided he needed more power for the SCCA Runoffs. Paid an engine builder $4500 for some "upgrades". The engine made 5 more HP than before, and the engine wouldn't spin past 7800 rpms. The same engine guy redid an engine I prepped for another guy. He said my shit was " all wrong". Changed the cam, changed the porting. He lost 19 hp compared to the old configuration. Less torque. Fewer rpms. He added huge domes and a ton of valve lift. Trouble is, the 1.9 heads start to flow worse at lifts above .450" when you've got big valves, and the domes kill flame travel and high RPM power.

Anyway, at the pointy end of the stick, the cams are pretty radical. The Swedes and Finns making good power with the newer 2.4 litre CIH engines are all well over .600" valve lift and damn near 290 duration @ .050" duration! But if they get the springs wrong (too much breaks parts, too little floats the valves), then it's junk.

For a 1.9 litre Opel CIH, the short stroke means uber-slow piston speeds. So the valves can catch up and pass the pistons. So you need big valve notches, resulting in low compression. Add a big dome and flame travel goes to hell in a hurry and it won't rev for a damn. So a modest done with some head milling gets you there a little bit faster. Hard to get over 11.5:1 compression with one if these engines and still have a decent camshaft. The valve notches eat up all the compression.

Given all that, I'd stick with a cam in the realm of .450"-.470" lift, and maybe 245-250 @ .050" duration. Tighten the LSA to 106 and it'll make some good torque in the mid range. I did a similar cam for a friend's autcross car and the torque was within 12 Ft lbs of peak from 2800-6200 rpms. Nice and flat. Peaky is impressive on the dyno but it doesn't hustle you out of the corners.

The 1.9 heads also crave intake flow. Huge headers hurt them. But they like solid intake port mods and induction.



Opel is a 4-letter word...
http://www.flickr.com/photos/10498579@N07/sets/



Edited 2 time(s). Last edit at 02/05/2015 02:09PM by Ascona73.
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Pete
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Re: 74 Opel Manta
February 05, 2015 04:36PM
Most people (meaning, not hardcore racer pervs) would consider a cam in the 240-250 @ .050" to be OMG HUGE and go to something smaller and then regret it.

You raise very good points, of course.



Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.
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EvanB
Evan Arthur
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Re: 74 Opel Manta
February 07, 2015 02:47PM
Just bolted on the new Weber 32/36, it actually runs now! I need to figure out a throttle cable linkage then get the brakes working to get it on the road.

And some muffling for exhaust.
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