Who has done a 904 to a 4 speed auto conversion. Would use a GM (done Pontiac/Chevy before 200R) if I have to. Don't want to do any cutting to the floor tunnel.
I don't need everyones opinion, just someones take on what trans they used, hands on themselves. Going to a 8.75 with a fairly tall gear (370-411). Power is not going
to be an issue.
Thanx in advance,
Thumper

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It's Going To Get Loud Real Fast !

You can fit just about any trans in your tunnel without mods. I'm assuming you have a Dodge D100 pickup. I hate to assume but since you provide absolutely no information....

What car? A-body needs substantial tunnel/X-member cutting for a 200-4R or A500 Mopar. Had A500 in my 68 Dart, now 200-4R with Wilcap adapter kit.

Any auto OD will require tunnel/X cutting, almost certainly. Buy a GV OD and put it on your 904 and more minor tunnel cutting well behind the X-member. That is easiest.

Lou

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Home of Slant6-powered fun machines since 1988

Sorry picture didn't download .....A body

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It's Going To Get Loud Real Fast !

Prepare to cut and weld...

Lou

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Home of Slant6-powered fun machines since 1988

Like the old tv show..


Chop..

Cut....

Rebuild.....


Greg

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http://www.youtube.com/hyperpack

Gross. The Torqueflite was one of the world's best automatic transmissions. The GM TH-200-4R was the opposite. I mean, it's your car, so you don't need a reason if you really want to cut it up and throw cubic hours and cubic dollars into this transmission swap to wind up with a very-much-less-nice transmission, but…gross.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

The 200-R4 is supposed to be okay when rebuilt with some aftermarket parts. Its a more efficient overdrive than the Torqflite O/Ds that Chrysler offered. I have no personal experience with the 200-R4. Its said to fit in most vehicles without extensive floor pan mods. If I have to cut the floor I wouldn't want to do it.

You might be able to use a Laycock o/d instead of a Gear Vendors - if you can find the adapter. This email address may help if you consider using a Laycock Volvo O/D : gpyzak@ix.netcom.com https://maximum-overdrive.com/contact-us/

The 'Achilles Heel' of Mopar is the lack of a good OD trans during all the non-computer years. Given the poor finances of Chrysler in the 70's and 80's....they never invested in anything beyond adding an OD unit to the back of the 904/727. A good trans, but not efficient and too big/heavy.

As an aside, that lump of human goo, Michael Moore, made a lot of hay with his 'Roger and Me' movie that portrayed Roger Smith, CEO of General Motors, as Satan on Earth. But Smith, despite whatever else, is credited for forcing GM to invest millions in the introduction/adoption of electronic fuel injection. Had GM not done that, the rest of the world would have had to foot the bill both in terms of cost and time.

Yes, it is too bad there was never a good RWD non-elec OD auto. I for one do not like running 2.76 axle gears or turning 4000 RPM on the hwy in my hopped up street Slants. I consider OD a must for modern driving. FWIW, going from the A500 4spd auto to an admittedly heavily modified 200-4R got me 2-3 tenths in the 1/4 mile (within the 13s) and at least 1 MPG gain on the hwy. I cannot comment much on long term reliability yet. Initial build quality was not so great but Extreme Automatics made good...

I will refrain from answering or commenting on political matters on this website.

Lou

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Home of Slant6-powered fun machines since 1988

Well said, BOTH points

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It's Going To Get Loud Real Fast !

So you do see my point...I've dealt with the same problem on many of my Hot rods, GTO 4.11 gear, 70 Z/28 56's even went w/a 700R in my 250 6cyl 47 coupe in just the last 8-10 years.. Evidently the A500 stood up well ?
I had no plan in hacking up the trans tunnel, there are some alternatives to doing that, that's why I asked that those who had experience in a swap give me there opinion.

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It's Going To Get Loud Real Fast !

The issue you face is one that has been faced by most of us Mopar guys. There is no good solution....some guys swap over to a manual gearbox with OD, others do 'over the top' things, and others just live with no overdrive. An A500 is decent but there's no way it's gonna fit without serious sheetmetal/crossmember frame surgery. It's big and long in all the wrong places.

I believe the o/d unit of the A500 and A518 and variants could be adapted like the Laycock aka "Gear Vendors". Maybe installed remotely. I think it would need a pump to provide oil for cooling. Making a splined shaft and adaptor would be straightforward for a machine shop, I don't know about the pump . These O/D units are common and dirt cheap. I think the requirement for cooling would make this too difficult. Fundamentally they are similar to the Gear Vendors. Maybe I'll get one and examine it. They are a planetary gear set like the Gear Vendors.

I have an A500 out of an 89 or 90 V-6 Dakota that I am going to install in my 76 D100 using a factory 60s era Mopar smallblock trans to slant six adapter.

The first five or six years of A500/A518 production only had one external switch to turn the OD on or off. Every other elecotrinic input can be worked around using line pressure switches as described here:

https://transmissioncenter.net/shop/pat ... g-diagram/

The A500s and A518s used identical New Process overdrive units, but these units cannot be adapted to a 904 or 727 due to the lack of certain passages drilled in the trans body.

Fortunately, I am driving a truck, not an A body. I don't have to modify anything except my motor mounts to gain the roughly one inch of space needed for the adapter. On an A body or passenger car, Gear Vendors (which is really the old Laycock de Normanville overdrive unit packaged better) is probably the easiest, but probably not the cheapest. Cheapest might be to scavenge a Laycock unit from a Volvo and fabricate your own adapter plate to make it a divorced overdrive unit.

For my application I spent about $130 on the factory adapter, $75-$100 at the local Pick and Pull for the trans, cooling lines (the A500 and A518 used larger diameter cooling lines than the 904/727), crossmember, OD switch and wiring, and I will need to get a new driveshaft made up. By beating the bushes and getting lucky, I should be able to put a four speed overdrive trans in my 76 D100 using all Chrysler parts for under $500. The issue for me is time. I have had the parts floating around my garage for two years but still haven't had a chance to install them. I will post a thread about it when I do.

For me, it just wasn't worth the cost or time spent fabricating to try and adapt some other brand four speed automatic transmission. But if I were in a passenger car I would take a hard look at smaller transmisions than the A500/A518. But Dan is right- the old Torqueflights can really take a lot of abuse.