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Conquest Rear Suspension too high

Garyhbates
Posts: 9
Joined: Fri Aug 12, 2016 12:21 pm

Conquest Rear Suspension too high

Post by Garyhbates »

My Conquest has been completed stripped down and reassembled over many years . After the chassis and rear axle were assembled i noticed that the back end sat too high . I always thought that the weight of the body would bring that down level but now all the panels are back on, the rear of the body still sits 80mm higher than the front (measuring sills to ground front and back) and is so high that the shock absorbers do not reach the mounting stubs on the base of the suspension springs. The original car looked very low at the back end so during the rebuild i had the original springs tempered but these are even worse than another pair i acquired (car is 120mm too high with the tempered ones fitted) . On the bench the tempered pair are 185mm (7.25") deep compared to the untouched springs which are 145 (5.75"). Of course this is not an easy way to compare their final height as the tension also has to be considered under load. The service manual shows that under load of 798lb it should move only 0.8inch and "free" (which i assume means under no load) it is 6.2 inches camber. So the amount that the spring compresses should be minimal and the bench height will very much be the depth that it will operate as unless the spring is really saggy under load. so the original springs are below the spec but still make the car sit too high unless i have assembled something incorrectly. The body is attached really close to the chassis at the back so it not being held away from it . no spare tyre or rear seats are yet in place but since they don't seem that heavy i can not imagine the car will drop 80mm when i add them. Any ideas would be welcome.

Brian-H
Posts: 87
Joined: Fri Aug 09, 2019 6:04 pm
Location: Loughborough

Re: Conquest Rear Suspension too high

Post by Brian-H »

I've had a look in a Conquest workshop manual that i have, and rear suspension is 10 pages , section "I".

If your manual is the same, the only thing I can think of, is that possibly the springs are different from what there should be for the chassis serial number. Pages 1 and 2 of section "I" list the differences. For each range of chassis numbers, there's also 2 types of springs, for "Hard Condition" and "Standard".

I can't think of anything else.

Chris_R
Posts: 531
Joined: Wed Feb 10, 2016 12:48 pm
Location: Twickenham

Re: Conquest Rear Suspension too high

Post by Chris_R »

This may be a totally dumb question because I don't know the Conquest but have you put them on the wrong side of the axle?

Garyhbates
Posts: 9
Joined: Fri Aug 12, 2016 12:21 pm

Re: Conquest Rear Suspension too high

Post by Garyhbates »

Thanks Chris , it is something quite fundamental ,i agree . The Spring is fitted under the axle as per the drawing in the manual. The fixings and shackle can only fit one way as far as i can see. i have attached a photo .

Brian has made a good point . I did look at the model number of the spring for DJ250 and my original springs are the correct model 426263-06 for the car chassis number . However those are the ones that have been retempered (too far) . The other pair are so rusty that i can not see the model number so could well be the wrong model. So my choices are both bad and both too high . I will see if i can get the 426263-06 ones bent back . i will aim to reduce them by 80mm but if anybody has any other measurements of springs off the car i would be grateful to learn what the distance should be .
Attachments
IMG_1304.JPG

Chris_R
Posts: 531
Joined: Wed Feb 10, 2016 12:48 pm
Location: Twickenham

Re: Conquest Rear Suspension too high

Post by Chris_R »

OK, another perhaps not so dumb question. Leaf springs will have a relaxed position when they are off the car whereby the shackles will be a certain distance above the centre. That's the "Free Camber". It's measure from a line joining the centre of the shackles down to the centre position of the spring. This should be specified somewhere. That's the first thing to check. If the free camber is too high it's likely the result in the car will sit too high.
The next thing is to get the Spring Rate. This is the amount of weight to depress the spring through the first inch of travel. The spring rate is affected by the number of leaves, the length of the leaves and the thickness of the leaves.
If you don't have this information from the workshop manual then perhaps talk to a couple of spring specialists who specialise in classic car springs and see if they have the information.

HenryC
Posts: 180
Joined: Mon Feb 15, 2016 8:31 pm
Location: Surrey / East Hampshire

Re: Conquest Rear Suspension too high

Post by HenryC »

I had this problem on another make of car.

It turned out that the shackle bolts at the rear of the spring were done up far to tight, effectively forming a rigid joint between the spring and chassis. The shackle was not free to move/rotate, so the spring remained in its 'free camber' position, even with the weight of the car resting on the axle/wheels. Even the front eye bolt can affect the lack of movement. Try loosening the shackle and eye bolts with the car sitting on its wheels, jump on it a few times and then retighten the bolts.

(I'm sure you are aware that it a rest position the rear springs should have negative camber).

Hope this might help.
Cheers, Henry

EL24
Conquest (Drop Head) Coupe DJ252
MGB 8-)

Chris_R
Posts: 531
Joined: Wed Feb 10, 2016 12:48 pm
Location: Twickenham

Re: Conquest Rear Suspension too high

Post by Chris_R »

Henry, what do you mean by "negative camber"? They should never go past the flat position. If they do then they are very much overloaded.

Brian-H
Posts: 87
Joined: Fri Aug 09, 2019 6:04 pm
Location: Loughborough

Re: Conquest Rear Suspension too high

Post by Brian-H »

Yep, in relation to leaf springs, I would have also wondered what "negative camber" meant if I hadn't got the Conquest workshop manual.

It means "convex" , the leaf spring is shown on a bench in that position (and loaded it goes "concave"). Yet for a wheel, camber is the angle of the wheel relative to vertical, or, it's the banking of the road on a corner. On a ship it's the convex shape of the decking across the deck from port to starboard.

Chris_R
Posts: 531
Joined: Wed Feb 10, 2016 12:48 pm
Location: Twickenham

Re: Conquest Rear Suspension too high

Post by Chris_R »

I don't think they should go past the flat position otherwise you are trying to bend upper leaves over the lower leaves.

Garyhbates
Posts: 9
Joined: Fri Aug 12, 2016 12:21 pm

Re: Conquest Rear Suspension too high

Post by Garyhbates »

Thanks Henry , I am very sure that i have tightened up all the bolts really tight . This would explain why it is all rigid and not taking the weight on the springs. This also explains the drawing in the manual which talks of negative camber (mine should be -0.8 ") . It shows that under load the eye bolts should be 0.8" BELOW the longest spring leaf . Currently its about 6 inches above it. See drawing attached.
The Free camber is quoted as 6.2" which is slightly less than i currently have 7.25" . So that looks like the data i was looking for .
The manual gives the spring rate as 114lbs , so i guess that means that off the car it should drop 1 inch when i apply 114lbs , conveniently i have a set of old sack scales which have 2 x 56lbs weights , so i should be able to test this .
Attachments
IMG_1305 2.jpg

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