Technical questions about 51/61xx 'adjustable' coil-overs

[gundrted+t4r]

I'm looking into the future and have some technical questions about the 51/61xx adjustable coil-overs. I'm not new to shock or lifting. I had 5100s on my Jeep and really liked them. I've looked some of the threads and haven't seen the info I'm looking for.

Shocks in general are designed to operate within a specific range of travel. A shock that operates extended risks toping out on the down stroke or over compressing on the up stroke. The converse happens when a shock operates compressed. Valving can also be a concern at different points in the shock stroke but thats getting a little down into the weeds even for me.

Enter the 51/61xx adjustable shock options. The adjustable spring plate effectively changes the length of the stroke of the shock. From the pictures the 'stock' setting looks to be in the middle of the stroke and 'lifted' setting looks like it rides about 2in higher in the stroke.

Having one shock do it all is great, but from a technical aspect is it really a good thing?

Wouldn't running these shocks with a +2.5in spring or raised spring plate risk top-outs and damage when fully extended?

Wouldn't the 'lifted' setting or +2.5in spring shorten the downward stroke and limit the travel vs a shock that built for a lifted length?

I really like the 61xx on paper, but wouldn't it be better to get a shock that built to a longer spec and have its full travel available all the time?

B8 5100 (Ride Height Adjustable) - Shock Absorber
Part Number: 24-196499
Series: B8 5100 (Ride Height Adjustable)
Position: Front
Descriptor: Front Lift Height: 0-2.5"

B8 6112 - Suspension Kit
Part Number: 47-259768
Series: B8 6112
Drive Type: 4WD
Position: Front
Descriptor: Front Lift Height: 0.8-2.5"

 

[RonJR]

Wouldn't running these shocks with a +2.5in spring or raised spring plate risk top-outs and damage when fully extended?

On the 4runner suspension, the shock is the limiter for the down-travel (full extension of the suspension). So, no, the shock will not be damaged when it extends fully, since that's what it is designed to do.

Wouldn't the 'lifted' setting or +2.5in spring shorten the downward stroke and limit the travel vs a shock that built for a lifted length?

The lifted setting does not change the upward (compressed) travel limit of the suspension. The upward travel is limited by the bump stop, and that doesn't change. The 5100 has enough compression range that it will not get crunched before the LCA hits the bump stop.

When you put a 5100 on a 4runner at other than the stock setting, you are simply moving the normal operating point (rest position) of the suspension, but the limits don't really change. For a stock 4runner, the suspension has about 3" of up travel (compression) and about 5" of down travel (at the wheel). Setting the 5100 for a 2" lift changes that to 5" of up travel and 3" of down travel. Same range, just different rest position within the range.

(Actually, I believe the 5100 is slightly longer than a stock shock, so will extend down travel perhaps another inch, but not more than that. CV joints start suffering if down travel extends too far.)

 

[gundrted+t4r]

On the 4runner suspension, the shock is the limiter for the down-travel (full extension of the suspension). So, no, the shock will not be damaged when it extends fully, since that's what it is designed to do.



The lifted setting does not change the upward (compressed) travel limit of the suspension. The upward travel is limited by the bump stop, and that doesn't change. The 5100 has enough compression range that it will not get crunched before the LCA hits the bump stop.

When you put a 5100 on a 4runner at other than the stock setting, you are simply moving the normal operating point (rest position) of the suspension, but the limits don't really change. For a stock 4runner, the suspension has about 3" of up travel (compression) and about 5" of down travel (at the wheel). Setting the 5100 for a 2" lift changes that to 5" of up travel and 3" of down travel. Same range, just different rest position within the range.

(Actually, I believe the 5100 is slightly longer than a stock shock, so will extend down travel perhaps another inch, but not more than that. CV joints start suffering if down travel extends too far.)

Thanks for getting a little into the technical weeds with all this.

This is very good info. Sadly it doesn't my the choice between OME or Bilstein any easier ... haha

 

[gundrted+t4r]

On the 4runner suspension, the shock is the limiter for the down-travel (full extension of the suspension). So, no, the shock will not be damaged when it extends fully, since that's what it is designed to do.



The lifted setting does not change the upward (compressed) travel limit of the suspension. The upward travel is limited by the bump stop, and that doesn't change. The 5100 has enough compression range that it will not get crunched before the LCA hits the bump stop.

When you put a 5100 on a 4runner at other than the stock setting, you are simply moving the normal operating point (rest position) of the suspension, but the limits don't really change. For a stock 4runner, the suspension has about 3" of up travel (compression) and about 5" of down travel (at the wheel). Setting the 5100 for a 2" lift changes that to 5" of up travel and 3" of down travel. Same range, just different rest position within the range.

(Actually, I believe the 5100 is slightly longer than a stock shock, so will extend down travel perhaps another inch, but not more than that. CV joints start suffering if down travel extends too far.)

I've been going over this in my head and following everything.

In the past (solid front axle) down travel is what I would look for in wheel travel. The more flex the better, but with the CV joints I see the point about damaging them with to much down travel.

If the 51/61xx shocks limited the drop within in a 'safe' level, is there a greater risk to the CVs going with something like an OME or other 3in lift? I wouldn't see .5 of an inch making or breaking it on a trail, for me.