Rear 4 bar dilemma.

[dave59]

Hi all i am fitting a 4 bar suspension to the rear of my pop, i have set it with the lower bars 24inches, the upper bars are 14inches to set them under the back seat,
will having different length on a parrel set up give me any problems,
any help would be greatfully recieved,

[mygasser]

if you only have a 2-3" of inches suspension travel it shouldn't matter. any reason you can't angle the upper bars down lower at the front so they can be equal length? had you considered a diagonal 4 link where the upper bars either come off the axle near the diff and angle outwards to the chassis (or off the axle tube top above the lower mounts and angling inwards to a crossmember under the back seat). either way you won't need a panhard bar to control sideways axle movement.
neil.

[Happydaze]

if you only have a 2-3" of inches suspension travel it shouldn't matter. any reason you can't angle the upper bars down lower at the front so they can be equal length? had you considered a diagonal 4 link where the upper bars either come off the axle near the diff and angle outwards to the chassis (or off the axle tube top above the lower mounts and angling inwards to a crossmember under the back seat). either way you won't need a panhard bar to control sideways axle movement.
neil.

Aren't equal length but not parallel 4 bars going to start busting stuff or just locking up? I'm struggling right now visualising what might happen. Should have kept my childhood Mechano! Not sure where the grandkids' Lego is either!

Chris



Sent from my SM-T515 using NSRA mobile app

[mygasser]

not if one end of the bars has a 'rose' joint or at least bushes with a degree of flex. to be fair with the amount of travel a typical rod has it won't be a problem. even parallel 4 bars have a degree of bind when one side of the axle is up and the other side down, like when on uneven ground. most 'rally' type 4 bar kits have 'rose' joints one end because of this.
neil.

[Happydaze]

I'm thinking very simply in two dimensions. A rectangle / parallelogram can articulate, a trapezium... will be OK too! Got my head around it! The equal length 4 bar will not give pinion angle changes though. Back to regular programming!

Chris

Sent from my SM-T515 using NSRA mobile app

[Blackpopracing]

I think my 4 bars on my pop are about 14" top & bottom and work fine.

[v8pop]

I think my 4 bars on my pop are about 14" top & bottom and work fine.

Mine are also all 14" like Mark's and as of yet had no issues. Hope this helps.

Cheers Tim W

Sent from my M2103K19G using NSRA mobile app

[mygasser]

that's a good alternative, shorten the lower bars to match the uppers.
neil.

[dave59]

that's a good alternative, shorten the lower bars to match the uppers.
neil.

Thank you all for your replies they are all a great help, i am going to use spherical rod ends at the
axle and urathan bushes at the frame, there doesnt seem to be any binding lifting the axle by hand but i am
worried about pinion angle change

[mygasser]

what's the suspension total travel from full droop up to the bump stops?
neil.

[dave59]

Hi Neil
Full suspension travel with the shocks fully open is 3-1/4inches.
Thank you for your replie.
Dave.

[Nobody]

youre have no issues with different lenght bars. some production mustangs have really short top arms. only thing id say is to mount them parrallel to each other when looking at the side.

if you have them at different angles it does put bind into the set up

[chevy2]

if you only have a 2-3" of inches suspension travel it shouldn't matter. any reason you can't angle the upper bars down lower at the front so they can be equal length? had you considered a diagonal 4 link where the upper bars either come off the axle near the diff and angle outwards to the chassis (or off the axle tube top above the lower mounts and angling inwards to a crossmember under the back seat). either way you won't need a panhard bar to control sideways axle movement.
neil.

Exactly what I did with my Anglia van,
used the front leaf spring point for the lower 4 bar and 2x diagonal bars from the top of the diff outwards, drives sweet.

[dave59]

Thank you for your help.

[Captain Scarlet]

Exactly what I did with my Anglia van,
used the front leaf spring point for the lower 4 bar and 2x diagonal bars from the top of the diff outwards, drives sweet.

I used leaf spring mount on Julies Thames van ,top mount was a additional crossmember ,(rubber bushed for compliance) parallel 4 bar in this case so a watts linkage for lateral location.

[Doug]

I used leaf spring mount on Julies Thames van ,top mount was a additional crossmember ,(rubber bushed for compliance) parallel 4 bar in this case so a watts linkage for lateral location.

*Julie’s

[Captain Scarlet]

*Julie’s

Yeah, smart phones, chubby fingers and a rushed response has a lot to answer for