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Dodge M-body Diplomat #1313662
10/01/12 12:03 PM
10/01/12 12:03 PM
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Posts: 15
Illinois
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Tinmans21 Offline OP
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Tinmans21  Offline OP
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Illinois
I have an 85 dodge diplomat that I plan on turning into a street sleeper. Right now i have the original 318 an a 383 block sitting around. I think it might be safer going with the 318 first an move on up to the 383 soo. . . question is i would like a A833 four speed to go in the car but without sacrificing the bench seat up front an i would like to put a 8 3/4 "489" casting in the rear. An does anyone know how to get a M-body to handle in the corners?

Last edited by Tinmans21; 10/01/12 12:44 PM.
Re: Dodge M-body Diplomat [Re: Tinmans21] #1313663
10/01/12 12:48 PM
10/01/12 12:48 PM
Joined: Jan 2003
Posts: 1,263
Southwestern Ontario Canada
racealittle Offline
pro stock
racealittle  Offline
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Joined: Jan 2003
Posts: 1,263
Southwestern Ontario Canada
Quote:

I have an 85 dodge diplomat that I plan on turning into a street sleeper. Right now i have the original 318 an a 383 block sitting around. I think it might be safer going with the 318 first an move on up to the 383 soo. . . question is i would like a A833 four speed to go in the car but without sacrificing the bench seat up front an i would like to put a 8 3/4 "489" casting in the rear. An does anyone know how to get a M-body to handle in the corners?




The Diplomat M body cars were available with a police package that was very effective for handling. I think it was called a S-21 package. The same option was often used in the taxi cab package.

The front swaybar is 1.25 inch, the rear was .75 inch. The rear cop springs had front eye segment bushings that had the 'comfort' holes filled with 3/8" rod and had red paint on the bushing. They had the police 15x7" steel slotted cop rims with dogdish caps. The rims weighed 2 lbs more the other factory steel 15" wheels. The extra steel helped to keep the wheels from flexing on hard corners.

The steering box is more performance oriented than stock.

The 8 1/4 rear axle is plenty strong. An 8 3/4 from b body 1966-67, or 1968-70 can be modified at the perches and used.

I have had a BB in an F body. I had it well sorted. There are many issues to consider. A 360 and a 383 are equal in performance when modified.

My advice is a hot rodded 318 or 360. It will be a better balanced car that should satisfy your needs.

I also did the 4 speed swap, but with bucket seats. An automatic with a shiftkit and 2400-2800 stall would be plenty of fun, (just tight enough for regular driving). I also found the 3.21, 8 1/4, rear axle to be the best compromise.


Too many cars, too many parts, too little coin, too little space to work in, too little time left to make it all happen! Update: down to one ride, still too many parts, a little more jingle in the pocket, gaining space, and it's going to happen this year!
Re: Dodge M-body Diplomat [Re: racealittle] #1313664
10/01/12 02:37 PM
10/01/12 02:37 PM
Joined: Oct 2012
Posts: 15
Illinois
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Tinmans21 Offline OP
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Illinois
are you aware of any kits available to really make it handle? I'm not sure but is it possible to lower the car? I know i can with the front torsion bar setup but im not sure about the back. I don't have a 727 laying around but i do have the original 904 or 999 I'm not sure which it had but would either of these hold up to a warmed up 318? maybe with a rebuild or shift kit? Thanks for your advice by the way.

Re: Dodge M-body Diplomat [Re: Tinmans21] #1313665
10/01/12 02:40 PM
10/01/12 02:40 PM
Joined: Dec 2004
Posts: 804
central CT
cudazappa Offline
super stock
cudazappa  Offline
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Posts: 804
central CT
An F-body 4 speed had a shifter handle that was designed to be used in conjunction with a bench seat.

An M-body can do reasonably well in the handling dept. The biggest detriment is the lack of torsion bar availability. Firm Feel currently offers 2 sizes above stock (All FJMs use the same T-bars, the cop bars got better bushings) and they aren't cheap (IIRC ~$700)

Good luck with it, they are fun cars.



1971 Challenger
Re: Dodge M-body Diplomat [Re: racealittle] #1313666
10/01/12 02:52 PM
10/01/12 02:52 PM
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick Offline
I Live Here
patrick  Offline
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Posts: 16,123
Grand Haven, MI
my old ride was an '86 5th ave, hot rodded. I rebuilt the front suspension with poly bushings, added a 1 1/8" cop spec front sway bar, monroe sensatrac shocks, 11.75" front brake swap, 5 leaf rear springs, 1" rear sway bar, and an 8 3/4" rear with a 3.55 742 limited slip & willwood 12" disc brakes. I also used some 17x8 mustang bullit wheels with 3/4" bolt on adapters and 255/50R17 tires.

I also ran an A500 OD tranny, and considered swapping an A833OD. my '76 duster has a bench seat with the 4 speed, using that shifter would work great with the stock split bench.

engine, I had a 360 with a comp XE262, headers, and RPM air gap and 600 edelbrock carb to start, but replaced it with the stock roller cam 318 short block, regrinding the roller cam by bullet with their HR259/316 lobe for both intake & exhaust, running home ported magnum heads, and using the same carb & intake. ran as strong as the 360, while delivering 16% better fuel economy (17.5mpg vs. 15 in mixed driving).

stick with the small block, and if you're going OEM heads, stick with magnums.


1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
Re: Dodge M-body Diplomat [Re: Tinmans21] #1313667
10/01/12 03:26 PM
10/01/12 03:26 PM
Joined: Jan 2003
Posts: 1,263
Southwestern Ontario Canada
racealittle Offline
pro stock
racealittle  Offline
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Joined: Jan 2003
Posts: 1,263
Southwestern Ontario Canada
Quote:

are you aware of any kits available to really make it handle? I'm not sure but is it possible to lower the car? I know i can with the front torsion bar setup but im not sure about the back. I don't have a 727 laying around but i do have the original 904 or 999 I'm not sure which it had but would either of these hold up to a warmed up 318? maybe with a rebuild or shift kit? Thanks for your advice by the way.




I gave you the info about the factory S-21 option for a number of reasons.

I was in the factory when we were building these cars. We built thousands of these for years. These cars did a pretty good job of carving corners at stock body heights and 225/70/15 tires.

I am suggesting that you can get everything you need from a wrecker, (if you can find one who didn't scrap them all out).

Every so often a well cared for police car from the era does show up for sale pretty cheap.

The 904/999 can do the job. Plenty of upgrade parts are available at reasonable cost.

I suggest to be carefull on how low you make the front end of this car. If you choose to run good headers; you can easily flatten 3 tubes on the crowning of the road in one intersection at high speed. Good, early 340 exhaust manifolds work pretty good, and true dual exhaust pipes exiting on the passenger side rear were available on Imperials in the 1981 or so era. They were also very common in Mexico on a model they called a Dart.

Lowering the back can be done by doing some homework on rear front spring hangers. An example would be to locate a set of superstock F body front hangers. They are about 6 to eight inches long. They can be cut short (to stock length), and drilled for holes where you need them. You can make 3 to 4 sets of holes and get the ride height you are looking for.

If you are stuck for locating the swaybars/springs/wheels from a S-21
package car, I have most of those items, but I am in Canada.

Last edited by racealittle; 10/01/12 08:52 PM.

Too many cars, too many parts, too little coin, too little space to work in, too little time left to make it all happen! Update: down to one ride, still too many parts, a little more jingle in the pocket, gaining space, and it's going to happen this year!
Re: Dodge M-body Diplomat [Re: cudazappa] #1313668
10/01/12 03:55 PM
10/01/12 03:55 PM
Joined: Jan 2003
Posts: 5,406
Pikes Peak Country
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TC@HP2 Offline
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Quote:

The biggest detriment is the lack of torsion bar availability. Firm Feel currently offers 2 sizes above stock (All FJMs use the same T-bars, the cop bars got better bushings) and they aren't cheap (IIRC ~$700)






Gary you running either of these bigger sized t-bars in your Dippy or where they the stock ones?

Re: Dodge M-body Diplomat [Re: Tinmans21] #1313669
10/01/12 07:01 PM
10/01/12 07:01 PM
Joined: Sep 2007
Posts: 14,889
up yours
Supercuda Offline
About to go away
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I converted my 87 Diplomat to four speed years ago. Used an A body A833 (non-OD). I used a Hurst Competition shifter and a truck handle to clear the bench seat and the ashtray, I smoke so the ashtray is usually open.

I got the shifter hump and pedal assembly from an 80ish (I think 81) Aspen and I also used the Aspen to make a template to cut the hole in the firewall for the clutch linkage to pass thru. In 81 they eliminated the hole in the M body firewall since a stick wasn't an option anymore.

I had all the info on GeoCities but here's a link to an archive http://www.oocities.org/motorcity/2398/mbody/mbody.html


They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
Re: Dodge M-body Diplomat [Re: TC@HP2] #1313670
10/01/12 07:11 PM
10/01/12 07:11 PM
Joined: Dec 2004
Posts: 804
central CT
cudazappa Offline
super stock
cudazappa  Offline
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Posts: 804
central CT
Quote:

Gary you running either of these bigger sized t-bars in your Dippy or where they the stock ones?




I ran a completely stock suspension with the addition of a cop rear sway. (not legal for F-Stock). I could've gone to a larger front sway (rules permit that) and the solid k biscuits (ooo illegal) for not more $$$ but shortly thereafter I was offered a 71 Challenger and had to sell the dippy.

Still one of the nicest cars I've ever owned (44k EASY miles when I got it).

Had a great conversation with Dick at Firm Feel last year about making an F/M handle. Biggest "challenges" to overcome is the front torsion bars and front shocks.


1971 Challenger
Re: Dodge M-body Diplomat [Re: Tinmans21] #1313671
10/01/12 07:16 PM
10/01/12 07:16 PM
Joined: Dec 2004
Posts: 804
central CT
cudazappa Offline
super stock
cudazappa  Offline
super stock

Joined: Dec 2004
Posts: 804
central CT
Quote:

And does anyone know how to get a M-body to handle in the corners?




Meant to ask, what is the intended use of the car? How far are you willing to go? Budget? In essence, what's your goals and asperations for it?


1971 Challenger
Re: Dodge M-body Diplomat [Re: cudazappa] #1313672
10/03/12 05:43 PM
10/03/12 05:43 PM
Joined: Oct 2012
Posts: 15
Illinois
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Tinmans21 Offline OP
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Illinois
My main focus will be there rear since it will see some strip time. As for the overall plan its being built as a sleeper so I guess I don't need to worry about turns that often. I'll have to see how the car handles once I get the motor in an back on the street. Thanks for all of your guys help an info!!!

Re: Dodge M-body Diplomat [Re: Tinmans21] #1313673
10/03/12 07:14 PM
10/03/12 07:14 PM
Joined: Dec 2004
Posts: 804
central CT
cudazappa Offline
super stock
cudazappa  Offline
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Joined: Dec 2004
Posts: 804
central CT
Quote:

My main focus will be there rear since it will see some strip time. As for the overall plan its being built as a sleeper so I guess I don't need to worry about turns that often. I'll have to see how the car handles once I get the motor in an back on the street. Thanks for all of your guys help an info!!!




The front does need some help. Solid Bushings for the K-frame. This will help your chassis reaction. Also, stiffen up the front unibody.

In the rear, you will basically "redesign" the suspension. You'll want to use A or B body springs (A springs are the basis for the SS springs) they will require different front hangers(MP, Firm Feel, etc). The FJM springs are really long and not stiff at all. Also with this swap, you'll be eliminating the iso-clamp so you'll have a round front spring eye bushing, and the rear end will be planted right on the spring. Then you'll use traditional A/B body shock plates.


1971 Challenger
Re: Dodge M-body Diplomat [Re: cudazappa] #1313674
10/03/12 08:23 PM
10/03/12 08:23 PM
Joined: Oct 2012
Posts: 15
Illinois
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Tinmans21 Offline OP
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Illinois
Awesome thanks. I'll prolly have a few more questions about a 318 to 390 build in the near future. That's uncharted territory for me so it's going to be fun. Thanks again for the help

Re: Dodge M-body Diplomat [Re: Supercuda] #1313675
10/03/12 08:53 PM
10/03/12 08:53 PM
Joined: Apr 2005
Posts: 236
Augusta, GA
Lightning Offline
enthusiast
Lightning  Offline
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Posts: 236
Augusta, GA
Quote:

I converted my 87 Diplomat to four speed years ago. Used an A body A833 (non-OD). I used a Hurst Competition shifter and a truck handle to clear the bench seat and the ashtray, I smoke so the ashtray is usually open.

I got the shifter hump and pedal assembly from an 80ish (I think 81) Aspen and I also used the Aspen to make a template to cut the hole in the firewall for the clutch linkage to pass thru. In 81 they eliminated the hole in the M body firewall since a stick wasn't an option anymore.

I had all the info on GeoCities but here's a link to an archive http://www.oocities.org/motorcity/2398/mbody/mbody.html





the pics have gone down from the site would you happen to have them saved still?

I'm also slowly working on my M- and have the 4-speed already, so I'll be watching this topic closely.

Re: Dodge M-body Diplomat [Re: Tinmans21] #1313676
10/03/12 08:59 PM
10/03/12 08:59 PM
Joined: Mar 2012
Posts: 168
Washington State, USA
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Winchester 73 Offline
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Washington State, USA
the usual corners are best advice.you guys are missing the obviose advice-WHIEGHT LOSS!

for starters get the following stuff:
aluminum mas cyl
mini starter
headers /sans cats
light rims

for starters dumpster the following stuff:
ac
cruise cont
emmisions junk

and last but most important -teke the bumpers apart and get rid of the "brace"? behind them and get rid of the compression bumper brackets and make some from aluminum to mount the chrome outer visual part of the bumper-300+ pouns whieght loss!i used to drive a wagon that i drove to the scrap yard and gave away the bumpers and drove without them and it instantly became a different car.even braking was noticably improved.the chrome outer shell of the bumper only whieghs about ten lbs,bolt just that on with some aluminum brackets and it would look stock.

Re: Dodge M-body Diplomat [Re: Winchester 73] #1313677
10/03/12 09:04 PM
10/03/12 09:04 PM
Joined: May 2005
Posts: 629
Michigan
dart1962_440 Offline
mopar
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Posts: 629
Michigan
Quote:

the usual corners are best advice.you guys are missing the obviose advice-WHIEGHT LOSS!

for starters get the following stuff:
aluminum mas cyl
mini starter
headers /sans cats
light rims

for starters dumpster the following stuff:
ac
cruise cont
emmisions junk

and last but most important -teke the bumpers apart and get rid of the "brace"? behind them and get rid of the compression bumper brackets and make some from aluminum to mount the chrome outer visual part of the bumper-300+ pouns whieght loss!i used to drive a wagon that i drove to the scrap yard and gave away the bumpers and drove without them and it instantly became a different car.even braking was noticably improved.the chrome outer shell of the bumper only whieghs about ten lbs,bolt just that on with some aluminum brackets and it would look stock.





Less weight never hurts. Lower center of gravity helps too.

Re: Dodge M-body Diplomat [Re: racealittle] #1313678
10/03/12 09:31 PM
10/03/12 09:31 PM
Joined: Mar 2012
Posts: 168
Washington State, USA
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Winchester 73 Offline
member
Winchester 73  Offline
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Joined: Mar 2012
Posts: 168
Washington State, USA
Quote:

Quote:

I have an 85 dodge diplomat that I plan on turning into a street sleeper. Right now i have the original 318 an a 383 block sitting around. I think it might be safer going with the 318 first an move on up to the 383 soo. . . question is i would like a A833 four speed to go in the car but without sacrificing the bench seat up front an i would like to put a 8 3/4 "489" casting in the rear. An does anyone know how to get a M-body to handle in the corners?




The Diplomat M body cars were available with a police package that was very effective for handling. I think it was called a S-21 package. The same option was often used in the taxi cab package.

The front swaybar is 1.25 inch, the rear was .75 inch. The rear cop springs had front eye segment bushings that had the 'comfort' holes filled with 3/8" rod and had red paint on the bushing. They had the police 15x7" steel slotted cop rims with dogdish caps. The rims weighed 2 lbs more the other factory steel 15" wheels. The extra steel helped to keep the wheels from flexing on hard corners.

The steering box is more performance oriented than stock.

The 8 1/4 rear axle is plenty strong. An 8 3/4 from b body 1966-67, or 1968-70 can be modified at the perches and used.

I have had a BB in an F body. I had it well sorted. There are many issues to consider. A 360 and a 383 are equal in performance when modified.

360 = 383? NEGATIVE!

360
cast crank
1.88 intake valves
small doglegged port heads(probly cracked)
long thin cyl walls
4 head bolts per cyl
wet intake manifold
expensive to get cu inches

383
forged crank
2.08 intake valves
bigger ports
5 bolts per cyl head
dry airgap intake stock
cheap to make into a 426

My advice is a hot rodded 318 or 360. It will be a better balanced car that should satisfy your needs.

I also did the 4 speed swap, but with bucket seats. An automatic with a shiftkit and 2400-2800 stall would be plenty of fun, (just tight enough for regular driving). I also found the 3.21, 8 1/4, rear axle to be the best compromise.



Re: Dodge M-body Diplomat [Re: Winchester 73] #1313679
10/03/12 09:44 PM
10/03/12 09:44 PM
Joined: Oct 2012
Posts: 15
Illinois
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Tinmans21 Offline OP
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Illinois
I took off the ac smog an my dip didn't have cruise from the factory an was missing all the exhaust from front passenger back. I have a video of it on YouTube back when it was red doing a one tire fryer lol. I want to get rid of all "bump cylinders" as I call em behind the bumpers. There's a site called dippy.org that I found that has some good info about weight loss on m-bodys as well. http://www.youtube.com/watch?v=fKBqiESfMQU&feature=youtube_gdata_player that should b the link of my dippy doing a one tire fire.

Re: Dodge M-body Diplomat [Re: Winchester 73] #1313680
10/03/12 10:14 PM
10/03/12 10:14 PM
Joined: Jul 2012
Posts: 298
mt. pleasant, PA
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Diplomat440 Offline
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mt. pleasant, PA
my 85 diplomat with totaly stock front suspension and a 440 handles a lot better than i thought it would. i used a 3.23 8 3/4 out of a 66 charger, and an a-833 and pedals out of an aspen. 71 b-body pistolgrip fits the bench seat perfect.
[image][/image]

Re: Dodge M-body Diplomat [Re: Diplomat440] #1313681
10/04/12 12:34 AM
10/04/12 12:34 AM
Joined: Oct 2012
Posts: 15
Illinois
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Tinmans21 Offline OP
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Joined: Oct 2012
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Illinois
It's real nice to see an actual picture. Thanks so much

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