Author Topic: 1974 Coupe deville questions  (Read 6329 times)

Offline Ville

  • Posts: 63
  • Name: Ville Korhonen
1974 Coupe deville questions
« on: June 30, 2015, 06:12:09 AM »
Hi!

I have 1974 coupe deville with 472cid.

Car is rare in my country and i need some help.


First thing which bothers me is chassis. If i drive speed bumbs and other bounces car wont bounce. It goes like newer car. Are these uncomfortabe? I had 79 electra which was more soft and smooth.

My one is not hard but i like very soft and loose.



Parking brake vacuum release wont work because hose are off. I have vacuum diagram but where is that neutral switch and what does it look a like?
CDV 1974

Offline chrisntam

  • Posts: 3472
  • Dallas, Texas
  • CLC Number: 29206
  • Name: Chris Jessen
Re: 1974 Coupe deville questions
« Reply #1 on: June 30, 2015, 07:56:56 AM »
Go to each corner of the car and push it down with your hands to or three times to get it going up and down.  Does it do that?  My thinking is that the shock absorbers may be bad, though normally, they become too loose and let the car bounce too much.

On the neutral safety switch, it is located on the steering column (on the top side) near the firewall.  It has both vacuum and electrical connections on it.  It is held on the column with a strap with screws.

That's how it is on my '70, yours is likely similar.

Where are you located?
1970 Deville Convertible 
Dallas, Texas

Offline Ville

  • Posts: 63
  • Name: Ville Korhonen
Re: 1974 Coupe deville questions
« Reply #2 on: June 30, 2015, 08:21:36 AM »
Sorry my bad english. I want that car bounces :) not stiff.

If i press corners, it wont give much stretch.

How about your cadillac? If we compare its softness/smoothness to 80's gm fullsizes.


Thanks about switch.

I live in Finland.


CDV 1974

Offline chrisntam

  • Posts: 3472
  • Dallas, Texas
  • CLC Number: 29206
  • Name: Chris Jessen
Re: 1974 Coupe deville questions
« Reply #3 on: June 30, 2015, 08:40:23 AM »
Your English is fine, we are communicating! 

I would disconnect the shock absorber and try bouncing it again.  If it bounces with the shock absorber disconnected, they are probably bad and replace them with new ones.

My car bounces.

chris.
1970 Deville Convertible 
Dallas, Texas

Offline Ville

  • Posts: 63
  • Name: Ville Korhonen
Re: 1974 Coupe deville questions
« Reply #4 on: June 30, 2015, 08:56:30 AM »
Nice to know :)

If my shocks are bad, which one are the most smooth/soft? I only can order rockauto etc so i have to choose: Ac delco, gabriel classic, monroe oe something and monroe matic?

Air shocks were smooth in my cutlass but those are expensive vs normal.

In firewall, under the hood, near to chassis (co driver side) is iron tank. Couple normal hoses goes to it and one nylon hose which goes under the car. Seems like air shock hose. Is that think vacuum tank or auto leveling system?


I tried look options on badge under hood but i only founded color, interior trim, 40/60 bench and vinyl top :D I looked on internet.



Is that eye on automatic high beam to low beam system long lasting? Or can i test it on flashlight?


All dash and cluster lights are also dark. Is there fuse or fusible link?


CDV 1974

Offline Ville

  • Posts: 63
  • Name: Ville Korhonen
Re: 1974 Coupe deville questions
« Reply #5 on: June 30, 2015, 08:58:36 AM »
there is tag from my car.
CDV 1974

Offline TJ Hopland

  • Posts: 10193
Re: 1974 Coupe deville questions
« Reply #6 on: June 30, 2015, 09:09:46 AM »
Iron tank is likely air ride compressor.   It was vacuum powered.   It seems pretty rare to find one that still works and even in the USA finding parts to repair one is not a sure thing.    That could explain why your car feels stiff.   Cars equipped with air ride had softer springs than cars without.   If / when the air shocks quit working this usually means the rear end of the car will sit a little to a lot low especially with a full tank of fuel.    Maybe since American parts are a little hard to find where you are someone improvised a way to get the car to ride at normal height and that is why its so stiff.     Rock Auto should have the air shocks.  If the compressor does not work you can buy a manual fill kit that has a air valve on it like a tire. 

That car has 3 fusible links, all located down near the starter coming off the main battery terminal.  One feeds the headlamp switch for the headlights.   One feeds the fuse box for the stuff that stays on all the time.   The last one feeds the ignition switch and then the rest of the fuse box for the things that come on with the key.    I think a 74 still had a connector on that harness about a foot from the starter that can sometimes cause issues.    I don't think they are your issue because you said just the dash lights don't work.  Those run off the always on fuse box side of things so check the fuse then maybe the part of the headlight switch that operates those and then the lights themselves.  They are not easy to replace unless you have very small hands and fingers so maybe they are all just burnt out.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Offline James Landi

  • Posts: 2388
  • 2007 XLR
  • Name: James Landi
Re: 1974 Coupe deville questions
« Reply #7 on: June 30, 2015, 09:20:31 AM »
Before you do anything, try inflating the tires to the recommended pressure.  34 psi will give you a harsh ride... not sure what the specs are for a '74, but I'm sure it's not over 30... also, entirely agree with air shock issue... some minor work will get those going again with a tire valve as suggested in the thread but this change will prove valuable.

Offline Ville

  • Posts: 63
  • Name: Ville Korhonen
Re: 1974 Coupe deville questions
« Reply #8 on: June 30, 2015, 09:40:55 AM »
Thanks!

Tire pressure is ok, ive tried 34-40psi and no change. Tires are 235/70 so those arent hard too.


Rear is like old mercedes and front is up but when i measure and compared to factory measures difference was maybe 1/4 ich but front was higher and rear lower.


So air shocks are my choice. How about front shocks manufactur recommends?

I noticed that bulbs are ruff places. One what I remowed was original so maybe those are just burnt.


Just under 70k miles in gauge.

Is somewhere database where car was in states etc? Arizona dealer sticker in glove box and maybe 2009 shipped in Europe.
« Last Edit: June 30, 2015, 09:46:11 AM by Ville »
CDV 1974

Offline Ville

  • Posts: 63
  • Name: Ville Korhonen
Re: 1974 Coupe deville questions
« Reply #9 on: June 30, 2015, 09:56:40 AM »
And yeah, a/c was problem too. Automatic climate control. Car does pretty good pressure when i press valve after running so i think there is stuff inside.

Vacuum heat switch is replaced with manual switch under the hood. It gives still heat and outside cool air when switch is open (coolant runs trough heater).

No vacuum leaks, only that parking brake hise is off but ive been plugged it.


Voltmeter gived 0.14 and other weird and small numbers when I measured a/c compressor magnetic switch.


What is common problem of these?


Blower runs high on defrost but lower and low with other positions, is that normal?

All positions works.

CDV 1974

Offline Ville

  • Posts: 63
  • Name: Ville Korhonen
Re: 1974 Coupe deville questions
« Reply #10 on: June 30, 2015, 03:30:41 PM »
Okay so fan wont work properly at all positions.

As soon as a/c works im happy.
CDV 1974

Offline James Landi

  • Posts: 2388
  • 2007 XLR
  • Name: James Landi
Re: 1974 Coupe deville questions
« Reply #11 on: June 30, 2015, 07:13:17 PM »
Before you do anything, try inflating the tires to the recommended pressure.  34 psi will give you a harsh ride... not sure what the specs are for a '74, but I'm sure it's not over 30... also, entirely agree with air shock issue... some minor work will get those going again with a tire valve as suggested in the thread but this change will prove valuable.

Offline Ville

  • Posts: 63
  • Name: Ville Korhonen
Re: 1974 Coupe deville questions
« Reply #12 on: June 30, 2015, 07:30:43 PM »
I tried lower pressure, nothing difference. Only tires looked emptier than before :)
CDV 1974

Offline Ville

  • Posts: 63
  • Name: Ville Korhonen
Re: 1974 Coupe deville questions
« Reply #13 on: July 01, 2015, 09:01:12 AM »
Does hood have latch like usual? Mine has not. I can just lift hood up.

Does light system on front fenders (which shows are bulbs ok) need sealed beam/original lights? I have h4 conversion because sealed beam is illegal there.


Is fisher body and shop manyal good or which i buy from ebay?
CDV 1974

Offline Eric DeVirgilis CLC# 8621

  • Posts: 7039
  • Name: Eric DeVirgilis
Re: 1974 Coupe deville questions
« Reply #14 on: July 01, 2015, 09:36:07 AM »
Does hood have latch like usual? Mine has not. I can just lift hood up.

Does light system on front fenders (which shows are bulbs ok) need sealed beam/original lights? I have h4 conversion because sealed beam is illegal there.


Is fisher body and shop manyal good or which i buy from ebay?

Under the front of the hood there should be a tab to release the secondary (safety) catch that must be lifted to raise the hood after the hood is first released from inside the car.

It's not good if its not there or working.

The lamp monitors on the front fenders work by way of fiber optics.

The normal headlight for these cars have a clear glass "pin" on the rear of the headlamp bulb. When the headlight is on, it projects a small ray of light into a fiber optic cable which conducts light to the the lamp monitors on the front fenders. My guess is that the headlights are lacking the means of projecting light from the rear of the bulb which is why the headlight monitors are not working.

The turn signal/parking monitors (outer lenses of the monitor) should still work however.   
A Cadillac Motorcar is a Possession for which there is no Acceptable Substitute

Offline TJ Hopland

  • Posts: 10193
Re: 1974 Coupe deville questions
« Reply #15 on: July 01, 2015, 10:01:23 AM »
73 I think was the first year that GM went to the under dash hood release so a 74 should have had one.  With these big heavy hoods what seems to happen is the springs get weak so it does not 'pop' when you pull the lever so it becomes a 2 person job to open the hood, one to sit inside the car and pull the lever and one to lift on the hood.    Instead of fixing the problem many people start doing something like using a long pry bar to trip the release from up front which ends up damaging the cable release part of the mechanism.   I will admit I am one of those 'some people'.   Its been on my to fix list for about 20 years now. 

There is a member here that goes by 'Cadillac Tim' that has written DIY service manuals for the climate control systems.    His manual just requires typical tools and is based on his experience repairing these things at the age they are now vs. when they were basically new.   I bought one to try and get mine working correctly and have read it and it looks like it will help me get the job done but I have not yet had the time to actually do it.   I believe he also has a website.

As far as which shocks to get in the front I have not really noticed a big difference in ride quality with what is currently available for these cars, they all seem to be in the realm of original equipment.   If these were a model that was popular to modify or it shared parts with a more popular cars then there may be more much stiffer options.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Offline Ville

  • Posts: 63
  • Name: Ville Korhonen
Re: 1974 Coupe deville questions
« Reply #16 on: July 01, 2015, 10:37:59 AM »
Rockauto says that 65-70 buicks has same shocks and same coil springs are in many same age gm full size.



I need overall shoo manual too, I think that haynes/Chilton books are too global and not specific.

These cars aren't super rare there but advices and tips are hard to get. I think that 80% are museum vehicles and their owners won't know about technic  ;D
CDV 1974

Offline EAM 17806

  • Posts: 557
  • GOD Bless America - Love It or Leave It For Good!
  • CLC Number: 17806
  • Name: Ev Marabian
Re: 1974 Coupe deville questions
« Reply #17 on: July 01, 2015, 10:53:41 AM »
My 76 CDV recommends air pressure to be 23 front and 24 in the rear, but I use 27 air pressure all around 4 tires. 1974-1976 CDV are basically the same cars with minor differences. Check your 74's tire pressure recommendation label which should be on the inside of the glove compartment.
« Last Edit: July 01, 2015, 10:56:04 AM by EAM 17806 »
Ev Marabian

1976 Cadillac Coupe DeVille, 1989 Chevrolet Caprice Classic, 1990 Pontiac Bonneville and 1996 Buick Skylark

Offline Ville

  • Posts: 63
  • Name: Ville Korhonen
Re: 1974 Coupe deville questions
« Reply #18 on: July 01, 2015, 10:57:07 AM »
Ive now tried tire pressure between 20-30psi and up. Ride is still stiff and tire pressure wont effect it  :(
CDV 1974

Offline 35-709

  • Posts: 5364
  • The most valuable antique is an old friend.
  • CLC Number: 4719
  • Name: G. Newcombe
Re: 1974 Coupe deville questions
« Reply #19 on: July 01, 2015, 07:07:35 PM »
If we are talking radial tires here, 23 to 24 pounds is way too low and a radial tire of Cadillac size (re: 235-75R15) is under-inflated at that point.  Those numbers are for bias-ply tires and are not proper for a radial tire.  30 pounds would be an absolute minimum, IMO, and 32 pounds would be better.

Do not use the recommended tire pressure label on the glove box door if you are running radial tires.

The best shop manual for your car is the Cadillac Factory Shop Manual, readily available on eBay Motors.  There are several up for sale there now including these ----
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050890.m570.l1313.TR0.TRC0.H0.X1974+Cadillac+shop+manual.TRS0&_nkw=1974+Cadillac+shop+manual&_sacat=6000

This Fisher Body Manual would also be very nice to have ---
http://www.ebay.com/itm/1974-CADILLAC-ELDORADO-DEVILLE-ORIGINAL-SERVICE-SHOP-BODY-REPAIR-MANUAL-BOOK-74-/131382399576?hash=item1e97005258&vxp=mtr
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

 

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