Author Topic: 1978 Seville Suspension  (Read 221 times)

Offline hjlint

  • Posts: 56
1978 Seville Suspension
« on: November 01, 2017, 08:06:41 PM »
 Has anyone found an improvement to the rear suspension on 1976 to 1979 Seville? Very harsh ride.
Hedley Lint

Offline Dave Shepherd

  • Posts: 1923
Re: 1978 Seville Suspension
« Reply #1 on: November 01, 2017, 08:13:19 PM »
I would say make sure the rear air shocks are not pumped up too far or binding, if the springs are weak the level control sensor would have the air shocks pumped up, this can cause a hard ride, of  course there are other possibilities, but start there.

Offline TJ Hopland

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Re: 1978 Seville Suspension
« Reply #2 on: November 01, 2017, 08:17:27 PM »
I too was thinking along the lines of the air level ride system.     If/when the systems fail the rear usually sags bad enough that most people will do 'something' to bring it back up.   That something could be the problem. 

Im not an expert on these cars but I think they did originally ride a little stiffer than say a Deville the same year. 
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Offline The Tassie Devil(le)

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Re: 1978 Seville Suspension
« Reply #3 on: November 01, 2017, 08:40:07 PM »
One of the causes of a harsh ride is tyre pressures.

Cadillac specified really low pressures, and the tyres always give the appearance of being half flat.

Anything much over factory pressure will give an increasingly harsh ride.

My '72 rides really softly at 23 Lbs, but I cannot stand such a low pressure, so I suffer it at 30 Lbs.

If I am going to drive "hard", I inflate to 35 to 40 Lbs.

Bruce. >:D
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Offline bcroe

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1978 Seville Suspension
« Reply #4 on: November 01, 2017, 09:36:49 PM »
Air shocks have failed for me, in one case jamming for a very
rough ride.  You have leaf springs?  A partial failure of these
might cause the air shocks to operate incorrectly.  Bruce Roe

Offline Eric DeVirgilis CLC# 8621

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  • Name: Eric DeVirgilis
Re: 1978 Seville Suspension
« Reply #5 on: November 02, 2017, 09:31:21 AM »
I always found 76-79 Seville to ride stiff compared to standard Cadillac models of the same era. I simply attributed this to the rear leaf suspension used in Sevilles of this generation. Presumably this suspension design was chosen to enhance handling as these cars were marketed to compete against European luxury brands ie, Mercedes Benz, BMW etc. which were designed more for handling rather than comfort.
A Cadillac Motorcar is a Possession for Which There is no Acceptable Substitute

Offline TJ Hopland

  • Posts: 6794
Re: 1978 Seville Suspension
« Reply #6 on: November 02, 2017, 10:23:36 AM »
The European influence / target is what I was thinking.     

Bruce reminds us of a good point about tire pressures.   Many of the modern ones do have a maximum pressure of at least 45 and want to talk about a terrible ride that is a way to do it.   Also the higher the mileage rating the stiffer the ride tends to be but we don't get a lot of choices anymore in our sizes.    Back when we had a rage of say a 30,000 mile or 80,000 mile tire both the 30 and 80 would have likely been a terrible ride but maybe the 50,000 option would have been good.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline hjlint

  • Posts: 56
Re: 1978 Seville Suspension
« Reply #7 on: November 03, 2017, 08:42:25 PM »
I too was thinking along the lines of the air level ride system.     If/when the systems fail the rear usually sags bad enough that most people will do 'something' to bring it back up.   That something could be the problem. 

Im not an expert on these cars but I think they did originally ride a little stiffer than say a Deville the same year.
I have checked the standing height, that is good.
Hedley Lint

Offline hjlint

  • Posts: 56
Re: 1978 Seville Suspension
« Reply #8 on: November 03, 2017, 08:45:12 PM »
I always found 76-79 Seville to ride stiff compared to standard Cadillac models of the same era. I simply attributed this to the rear leaf suspension used in Sevilles of this generation. Presumably this suspension design was chosen to enhance handling as these cars were marketed to compete against European luxury brands ie, Mercedes Benz, BMW etc. which were designed more for handling rather than comfort.
I think you are correct on this. Highway driving it is fine.
Hedley Lint

Offline hjlint

  • Posts: 56
Re: 1978 Seville Suspension
« Reply #9 on: November 03, 2017, 08:54:16 PM »
Air shocks have failed for me, in one case jamming for a very
rough ride.  You have leaf springs?  A partial failure of these
might cause the air shocks to operate incorrectly.  Bruce Roe
I have replaced air shocks twice with no success. The rear is that stiff that it barley moves when I push down on the rear bumper.
I'm going to disconnect them and see if this softens the rear.
Thanks for all responding.
Hedley Lint

Offline Dave Shepherd

  • Posts: 1923
Re: 1978 Seville Suspension
« Reply #10 on: November 04, 2017, 03:21:57 PM »
If the springs are not de-arched causing this, then frozen front spring hanger bushings can be part of the problem.

Offline hjlint

  • Posts: 56
Re: 1978 Seville Suspension
« Reply #11 on: November 06, 2017, 10:49:55 AM »
De-arched is something I haven't heard before. The springs are ayou.bout flat with air in the shock. Standing height is within specs.
Something I need to research further.
Thank
Hedley Lint