wagon rear shock question

Suspension, including wheel, tire and brake.
jon510
Posts: 80
Joined: 31 Jul 2012 16:01

wagon rear shock question

Postby jon510 » 26 Mar 2016 22:55

I'm in the process of swapping out my wagon rear suspension and am looking to source some shocks. I have perused the realm and have not found much info on what to do when changing the leafs themselves (re-arcing, adding a leaf, new springs) if there is a change in the eye to eye distance on the shocks.

I've got 215lb form flex composite springs made up, one is in and the other I'm having a heck of a time getting the front eyelet bolt out of. Anyway, on the one that's mounted, I measured the uncompressed and compressed lengths of the lower shock up upper shock mounting points. Uncompressed it's 17". Compressed is only down to about 15", although I think it's the spring that's limiting travel - there is no contact with the bumpstops, but the car starts coming off the jacks. The caveat is I'm just jacking up the one side since the other side is in progress, I'm not sure if things would be different if I jacked the whole diff/rear end up in the center.

My understanding is that I'm supposed to take compressed and extended length with the new springs and then match up to a shock. It doesn't seem like a lot of travel is needed, but then again maybe when the car is under weight and hits a bump it will compress more. The stock shock lengths are 20" uncompressed and 12" compressed.

My question - do I have to find a shock that matches up almost perfectly with these compressed and uncompressed lengths, or does something with that range still work? Ie, the range that the stock shock travels includes 15-17", will this work? My impression from reading around was that you really wanted to match the shock to the travel once the spring is on, although I'm not sure if I'll find anything with that limited a travel range. Or maybe I'm doing something wrong here.

Thoughts? Thanks!

Jon
69 2dr z20 turbo
71 wagon ld20 turbo, almost

datzenmike
Supporter
Posts: 5224
Joined: 24 May 2006 12:40
Location: Van. Isle.

Re: wagon rear shock question

Postby datzenmike » 27 Mar 2016 08:46

An underweight car will compress the shocks less than a heavy one.

If the shock is removed from the bottom mount and compressed fully, measure up from the mount to the bottomed shock to get the ride height difference. Now measure up that distance from the axle at any point you might worry about clearance. This is how high the axle would have to be to bottom the shock out.

I doubt that you will be raising the ride height so I'm assuming you are keeping or lowering it. A stiffer spring rate (again I assume you are probably increasing not decreasing the rate) will reduce suspension travel distance compared to the stock 'lighter' spring. IF fully compressed, the suspension is going to bottom on the rubber bump stops long before the shock does. Who would design a suspension where the shock bottoms out first??? I wouldn't worry about it.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

jon510
Posts: 80
Joined: 31 Jul 2012 16:01

Re: wagon rear shock question

Postby jon510 » 27 Mar 2016 22:18

I'm not sure I totally follow the process you describe. But I don't think any of the shocks I'm looking at will have the potential to bottom out before the suspension does. I guess what I'm wondering now is, if my extended height with the car in the air is 17", but I pick a shock with an extended length of 20", does this actually matter? I gather I'm supposed to match my extended length as best possible, but if my extended height of the suspension is less than the extended height of the shock itself, and the compressed height of the suspension has a larger measurement than the compressed height of the shock, is this really an issue? I'm thinking of getting the camaro/Ae86 rear inserts which actually measure almost identical to that of the stock shock (12" compressed, 20" extended), and springs limit me to 17" extended and won't be shorter than 12" eye to eye when compressed. So is there a problem with only using a portion of the shock travel or is this moot as long as I don't bottom or fully extend before the springs do?


Jon

User avatar
510longroof
Posts: 12
Joined: 26 Feb 2013 18:20
Location: Hamilton Ontario Canada

Re: wagon rear shock question

Postby 510longroof » 28 Mar 2016 17:04

I think I see where you are going with this. It is equally important that the shock doesn't "top out" before the suspension tops out. If the total travel in the suspension from fully compressed on the stops to fully extended, hanging with no load, falls within the range the shock can handle you should be good. The shock will work the same no matter where it is in it's range of travel.
71 510 wagon
67.5 1600 roadster project
74 CB360T project
I was in film, then television and now radio.

jon510
Posts: 80
Joined: 31 Jul 2012 16:01

Re: wagon rear shock question

Postby jon510 » 31 Mar 2016 21:07

That's pretty much what I was wondering, thanks. Hoping the shocks I ordered will work out now given their stroke range has my minimum and maximum within it. Thanks

Jon


Return to “Suspension”



Who is online

Users browsing this forum: Bing [Bot] and 4 guests