After enjoying the slightly bizarre handling and ride characteristics of my Fifth Avenue for some 18 months I think the time has come to get the thing to drive "properly".
This is especially pressing as I am about to (finally) de-emission the beast and fit a 4 barrel, Edelbrock intake, MSD, etc. and if funds allow get a Hughs cam in it, duals, etc.
I have a number of issues with the way the old barge drives and I think I'd like to concentrate on these.
1. Braking: If I run my BF Goodrich whitewalls at the recommended pressure I lock the rears on moderate braking on a wet road and they lock easier than I'd like in the dry too. This is scary. I think this is a front/rear weight transfer thing causing the back end to go light. I'm thinking that a set of decent aftermarket shocks will tame this (although I'll miss the see-saw action when you come to a halt LOL) am I barking up the wrong tree with this? carrera or Monroe gasmatic come recommended. Anyone used the KYBs on a barge?
2. Braking again: gentle application of the brakes seems to have little effect in slowing the car and then they come on pretty hard if you push any more, this is not a soothing ride for passengers... Plan is to replace vacuum hose to servo, maybe get a service kit for it if there is one available, and flush the fluid.
If the above has not made it sound like a death trap, we'll progress on...
3. Directional Stability: at high speed (OK, much above 55) the car becomes quite twitchy. At motorway speeds you can induce a kind of pendulum motion of correcting and recorrecting if you have to make any kind of emergency lane change or something. This gets far worse with any weight in the back (luggage or spare transmissions in the trunk etc.)
I'm thinking that HD front and rear sway bars, checking the front end geometry again and the afore-mentioned shocks will help here. Any other suggestions?
I don't want to loose ride quality.
I'd like it to be a more pleasant drive though. Long drives at higher speeds are not relaxing due to the twitchiness etc.
Round town its perfect (braking aside) but I'm retiring it from daily use to be a weekend motorway cruiser so I need to sort these issues out.
Making a boat drive like a real car?
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Anonymous
I was thinking the sway bars should stop it getting twitchy at speed as it seems to be that a small deflection and the resulting correction causes the car to roll off centre, thus requiring another correction and so it goes on...
Lowering it might also help here, bringing the center of gravity down a bit.
Lowering it might also help here, bringing the center of gravity down a bit.
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Anonymous
Poly bushes may well help with the classic 'waft' of an old barge.
I got a set for the Victor from Super Flex (well Victor isn't listed for the fronts, but I took HC Viva and am seeing what will fit).
Shocks will supress the natural frequency of the suspension, that is the pendulum motion you described. Adjusting the shocks will change those characteristics.
Also look at the spring rates of the springs themselves, it could be that there are stiffer springs that would be more suitable for your vehicle.
Tyre size (profile) has an effect on the general handling, large profile allows a larger lateral movement of the wheel under a cornering load... more 'waft'. Try to find a happy medium between 'waft' and 'crash bang'.
Sway bars will help with lateral stability particularly on the front, but I have been told of conflicting arguments as to the use of rear sway bars. They do shift the weight transfer about a bit (force path analysis), so look into them closer before deciding.
My rear brakes have a habit of locking up at the rear to (Charger), I guess an adjustable proportioning valve would help this.
I got a set for the Victor from Super Flex (well Victor isn't listed for the fronts, but I took HC Viva and am seeing what will fit).
Shocks will supress the natural frequency of the suspension, that is the pendulum motion you described. Adjusting the shocks will change those characteristics.
Also look at the spring rates of the springs themselves, it could be that there are stiffer springs that would be more suitable for your vehicle.
Tyre size (profile) has an effect on the general handling, large profile allows a larger lateral movement of the wheel under a cornering load... more 'waft'. Try to find a happy medium between 'waft' and 'crash bang'.
Sway bars will help with lateral stability particularly on the front, but I have been told of conflicting arguments as to the use of rear sway bars. They do shift the weight transfer about a bit (force path analysis), so look into them closer before deciding.
My rear brakes have a habit of locking up at the rear to (Charger), I guess an adjustable proportioning valve would help this.
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Anonymous
Cheers chaps.
I'm afraid that so long as nothing squeaks, knocks or looks split I consider bushes to be OK!
Shocks don't leak and the old "push & release test" settles the car back in 2 oscilations which seems correct. Its just I suspect that the energy given by hitting a subsidance patch on the motorway or whatever is significantly greater than my 12 stone hufting a corner in turn... Its 5200 lbs of car acording to the door plate! Good job Chrylser didn't build a true full-size in '86 you'd need a HGV licence to drive it...
I've heard the KYBs are a little harsh and the Monroe Gasmatic is a better bugget option and the Carrera is a better shock for a bit more dosh. Again ride quality is high on the priority list. Anyone got any comments from British roads on any of the above?
I'm nervous about poly bushes as I'd like a smooth compliant ride. Not sure if anyone does them for the M body anyway.
If I can get hold of new cop spec rear springs (or wagon springs) I'd be tempted with them as with 4 up and luggage you can bottom the rear out if you hit a moderate bump at speed. I'm sure the stockers must be weak as that can't be right either, although I've read the road test from '87 on a new one and they really tore it appart for its flawed driving manners, and yes, I read this before I bought the car...
I'm wondering about replacing the rear leaf "isomounts" with something made of solid metal, apparently some cop cars based on the Diplomat had this mod, although this was to keep the rear axle located under hard cornering and reduce hop rather than other handling woes. I'll certainly do this is I ever fit up a 8.75" rear which I'd like to do to get a better choice of gear ratios. Thats not a job for this winter though...
The tyres are a bit like balloons - 215/75x15 and white walls, so probably minimal sidewall reinforcement. I did get some 7.5x16 American Racing jobbies but these got "lost in transit" and nope I was not insured.
I might try some Lexus alloys on it as they are the same PCD and come in a 16" and a 17" OE. I'll buy them locally this time...
Again, its not initial understeer/slow turn-in or any of the things I'd associate with "flabby" rubber, its the bizarre inline oversteer which worries me.
Its probably cheaper and more effective to just go buy a 15 year old BMW 7 series or Jag Sovereign but thats not the point...
I'm afraid that so long as nothing squeaks, knocks or looks split I consider bushes to be OK!
Shocks don't leak and the old "push & release test" settles the car back in 2 oscilations which seems correct. Its just I suspect that the energy given by hitting a subsidance patch on the motorway or whatever is significantly greater than my 12 stone hufting a corner in turn... Its 5200 lbs of car acording to the door plate! Good job Chrylser didn't build a true full-size in '86 you'd need a HGV licence to drive it...
I've heard the KYBs are a little harsh and the Monroe Gasmatic is a better bugget option and the Carrera is a better shock for a bit more dosh. Again ride quality is high on the priority list. Anyone got any comments from British roads on any of the above?
I'm nervous about poly bushes as I'd like a smooth compliant ride. Not sure if anyone does them for the M body anyway.
If I can get hold of new cop spec rear springs (or wagon springs) I'd be tempted with them as with 4 up and luggage you can bottom the rear out if you hit a moderate bump at speed. I'm sure the stockers must be weak as that can't be right either, although I've read the road test from '87 on a new one and they really tore it appart for its flawed driving manners, and yes, I read this before I bought the car...
I'm wondering about replacing the rear leaf "isomounts" with something made of solid metal, apparently some cop cars based on the Diplomat had this mod, although this was to keep the rear axle located under hard cornering and reduce hop rather than other handling woes. I'll certainly do this is I ever fit up a 8.75" rear which I'd like to do to get a better choice of gear ratios. Thats not a job for this winter though...
The tyres are a bit like balloons - 215/75x15 and white walls, so probably minimal sidewall reinforcement. I did get some 7.5x16 American Racing jobbies but these got "lost in transit" and nope I was not insured.
I might try some Lexus alloys on it as they are the same PCD and come in a 16" and a 17" OE. I'll buy them locally this time...Again, its not initial understeer/slow turn-in or any of the things I'd associate with "flabby" rubber, its the bizarre inline oversteer which worries me.
Its probably cheaper and more effective to just go buy a 15 year old BMW 7 series or Jag Sovereign but thats not the point...
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Dave-R
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I've heard the KYBs are a little harsh[\quote]
If you heard this from an American don't believe a word of it. Anything that does not feel like sitting on a huge jelly feels 'harsh' to most Yanks. Sorry if that sounds insulting to any American chaps reading this.
In a car of the sort of weigh yours is I think you would be safe trying the KYBs. I think they will make a big difference plus they are pretty cheap.
Not sure exactly what they are but if they allow sideways movement of the axle under any kind of load get rid of them.I'm wondering about replacing the rear leaf "isomounts" with something made of solid metal
The KYB's will be fine mate, I have fitted loads of them and the cars ride well but straight line stability will go up.
Check the front anti roll bar drop links are in good order as well, they have a habit of breaking up, a cheap thing to replace and it can transform the ride, I agree about poly bushes, I never use them except...on the drop links !
What tyre pressures are you running? the pressures in the book are most likely for xplies and bear little relation to radial pressures.
Check the front anti roll bar drop links are in good order as well, they have a habit of breaking up, a cheap thing to replace and it can transform the ride, I agree about poly bushes, I never use them except...on the drop links !
What tyre pressures are you running? the pressures in the book are most likely for xplies and bear little relation to radial pressures.
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Anonymous
its an '86 so I guess they were on radials by then even on the M-barges!
Isomounts are a rubber pad that goes between the spring perch on the axle and the leaf itself. well, theres slightly more to it than that, but its like a GM body mount but for an axle.
Yeah, I'm fairly sure it was on the the C-Body Dry Dock that KYBs were getting less than rave reviews.
Isomounts are a rubber pad that goes between the spring perch on the axle and the leaf itself. well, theres slightly more to it than that, but its like a GM body mount but for an axle.
Yeah, I'm fairly sure it was on the the C-Body Dry Dock that KYBs were getting less than rave reviews.
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Anonymous
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Anonymous
KYBs rule! (Kayaba) . OEM on many cars.
Sachs and Boge seem to be the worst shocks you can buy from experience
im sure you;ve checked the tracking but that is a big suspect when it comes to straight line vagueness and pendullum. Especially if toeing out. As weight shifts to Rh wheel, it steers the car more to the right, forcing more weight to the LH wheel, so it then has a preferance to drift over to the left, etc etc. see what i mean?
Will
Sachs and Boge seem to be the worst shocks you can buy from experience
im sure you;ve checked the tracking but that is a big suspect when it comes to straight line vagueness and pendullum. Especially if toeing out. As weight shifts to Rh wheel, it steers the car more to the right, forcing more weight to the LH wheel, so it then has a preferance to drift over to the left, etc etc. see what i mean?
Will