Tubular front control arms.
 

Installed the control arms on my 65 Lemans. After temporary installation of the control arms without springs I noticed the shocks don't go to the end of suspension travel about an inch shy top and bottom.
Is this normal ?

Do You have the bump or Limit stops in yet?

Yes, but the one on top didn't touch, but it seems if I move it to where the one was on the original upper control arm, it looks like it will hit then.

Never tried that with the springs out, but one would think it they should go to limit. But front end probably will get to the stops anyway unless on hoist.
Maybe someone else has tried?

Be sure the ball joints esp uppers are not binding at full range.

If it causes issues I will likely just put the original shocks back on, they are still good.

They don't. But you bring up a good point.

If the shock limits travel it will destroy the shock on rise/lift. It will hammer them and they will leak, for one.

Shocks are generic to a degree to fit more applications, especially cheap shocks.

If you get 24k miles or 7 years out of most main-stream shock, I would be, um, shocked.

With that said, buy/source the correct shock for the application. Many manufacturers, or at least the 'ok' to 'good' ones provide dimensions, as well as travel info.

Shocks are one of those things when once you change them for new ones, you realize just how bad the ones you took off were.



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Bolded area is the cause. Pretty much all off the shelf GM shocks are the same part now, regardless of total travel of the actual car they are being installed in.

It's typically not an issue for your typical street car, or even high performance street car. Unless you're running around on slicks and have a lot of front end lift with traction, you'll never hit the rebound limit of the shocks.

If however your car has a good bit of power and traction, you'll either need to source longer shocks, or install travel limiters.

Dips in the road at speed will cause them to reach end of travel.

I remember in the Tokico shock days they were too short in travel, and I ate them up on the road.


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I have a '64 Lemans that I put Hotchkis control arms on the front and really struggled with this issue. At full extension the stock shocks are about 2" short. I do have droop stops, but they allow more travel than stock. Hotchkis acknowledged this problem, but essentially said it would only be a problem if you were wheelstanding on a regular basis. They claimed in normal street driving it would not be a problem, but I do not like my shocks acting as droop stops. I also unbolt top shock nuts if the wheels are going to be hanging for any period of time. It is a hassle. I did try to find a longer shock that would fit, but was unable to do so within the Bilstein line.

Most of the shocks on the market have 4 to 4.25" of travel in them. This is theoretically more than enough travel for most GM applications. The First gen F-Body for instance only has about 6" of suspension travel at the wheel. Accounting for its motion ratio that is near 2:1, technically speaking a shock with 3" of travel would be sufficient.

The problem occurs in how many cars are setup. On stock and near stock applications the suspensions are setup with 60-70% of the rebound travel being active at ride height. This gives you more compression distance, which provides better ride quality. Bump travel distances are typically more important on street cars.

The effect of that however is that you don't have a lot of droop travel left for potholes and such. In that situation, it's possible without a limiter, that you would use the shock as the travel limit.

This is one of the inherent problems with aftermarket control arms. Almost all of them as designed, remove any factory droop limit that is actually allowing the arm to articulate further than it would if it was the stock arm.

The cure for this is to bring your bump and droop percentage closer to 50/50 or even around 40/60 which is more typical of a performance oriented suspension. The trade-off in doing that is you typically have to lower the car and run heavier rate springs. This is not amenable to a good many classic car enthusiasts. For those people, finding a way to utilize the factory droop stops, or using other forms of travel limiters is necessary with most modern shock offerings.

I just recently replaced the front upper & Lower control arms on my '68 GTO and I replaced the shocks as well. The '65 and '68 are different, but I do not see how the shock when allowed to fully travel will not be long enough to reach to the top and bottom.
The problem I faced when installing the shock with the 1-inch drop springs was compressing the shock enough to put in the two bolts securing the bottom of the shock to the lower control arm.
The springs were installed, and the spindles were properly torqued. The full weight of the car was on the springs and control arms, so they were compressed. The shocks had no difficulty reaching to the top of the shock tower.

This is always how I recall installing shocks, except the Tokicos, and had multiple types/manufacturer's lower & upper arms. I don't ever recall using OE or general replacement shocks tho. Think I tried some Gabriels at one point, but they lasted maybe 5k miles before they were toast.

When I did shocks tho, I always had the car on jack stands and the wheels drooping. No way can you get a shock in there with the car on the ground.

I do remember the captured nuts in the control arms breaking, from trying to draw the shock up the last bit. Most aftermarket arms have actual nuts welded to them.

I don't think a drop spring would have made a difference, the suspension travel was always the same that I recall.

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For the most part shocks are less susceptible to failure from extention as most shocks have an internal bumper to help prevent damage from extention. On most of our cars the limiting factor of the rear suspension dropping is the shock.

However shocks are not tolerant of being compressed completely. Bottoming the suspension out when hitting a pothole or other bump will blow the seal or damage internal components. Some shocks have a rubber cushion on the shaft to keep the shock from bottoming out internally.

For example on my Burban I was given the wrong front shocks by the parts house. I failed to double check the part number I received with what I ordered. The truck had air bags and just airing down the bags a couple of times (with zero miles driven) was enough to blow the seal on one of the shocks.