Need advice on front bump stops for a G-body

[SSninja]

I'm installing a set of Spohn front lower control arms onto my '87 Monte Carlo SS and noticed that there isn't a provision for a bumpstop on the arm (The only available hole is for the sway bar endlink).

I do have a set of these bumpstops and it was suggested to me that I install them on frame facing the control arm: http://www.summitracing.com/parts/ens-9-9103g/overview/


The other option would be a slightly bigger bumpstop (Such as this: http://www.summitracing.com/parts/ens-9-9154g/overview/ ) or a shaft-mounted bumpstop on the shock: http://www.spohn.net/shop/1978-1987-GM-G-Body/Suspension/Tubular-Front-A-Arms-Accessories/Progressive-Rate-Shock-and-Strut-Shaft-Mounted-Bump-Stops-Pair.html


Any suggestions would be welcome. Definitely a little bummed as I've already had some fitment issues with the arms (Needed to shave down the Delrin bushing ends a hair for them to fit), and I noticed that the UMI arms do have a bump stop built in. I chose the Spohn arms as there was a package deal on the uppers and lower arms, which I'm using with tall upper and lower ball joints.

[exwestracer]

One note about your fitment problem with the bushings. Make SURE the inner sleeves are slightly longer than the cheeks of the bushings. You want the bolt clamping the sleeve, not pressing the mounting ears against the plastic.

Nothing at all wrong with the shock shaft bump stops. Most all race cars with coil overs use that design. You didn't say what type of shocks you have, but that would be the simplest solution if you can remove the end of the shock to install them. If you are going to use frame mounted stops, I would look for the ones with a flat end that can lay across the arm. Something like these:
70548
Those pointed ones may slip to one side of the round tube and allow the arm to travel past where you want it to stop.

[SSninja]

Thanks for the advice, Ray.

The bushings were originally a little wider than the inner sleeves (Which is why the arm wouldn't fit), but they're now flush. Sounds like I should trim them some more?


I currently have Bilstein shocks.

Do you know of any other options for a shaft-mounted bump stop? The ones that I listed from Spohn are for an 18mm shaft. I'll have to measure the shaft of my Bilsteins.

I'm familiar with using bump stops with struts, but I've been told that the shock body I'm using may not be suitable for use with a bump stop and that I'd be better off with a frame-mounted bump stop.

[exwestracer]

Dave,
With Delrin, the arm should travel FREELY up and down with the bolts tight. That Delrin has no "give" to it; so if the arms are bound up, you either need to trim the bushings more, OR check the alignment if the bolt holes.

[exwestracer]

Can you post a picture of the whole shock?

[SSninja]

When you say freely, do you mean that the arm should fully drop if not held up? There is a little bit of resistance when moving the arm up and down currently.

[exwestracer]

When you say freely, do you mean that the arm should fully drop if not held up? There is a little bit of resistance when moving the arm up and down currently.

If I were setting it up, I'd like to see the arm fall straight down when I let go of it. Think of what you would expect with a rod end or steel on steel bushing in there.... Like I mentioned earlier, the problem could possibly be the alignment of the bolt holes in the brackets. Did you have ANY trouble getting the bolts in?

[SSninja]

No, the bolts went through cleanly once everything was lined up.

I know that the Delrin bushing is at best flush with the inner sleeve if not a little longer.

[rentedmule]

I run Spohn LCAs with the Delrin bushings and had no fitment issues. I rely on the shaft-mounted stops on my shocks and have not seen anything to indicate that the LCAs have contacted the frame after a few seasons of racing.

Off topic a bit but how well do the end link tabs on your LCA line up with the swaybar on your car? The tabs on several of the aftermarket G-body LCAs don't line up well when they're used on the S-series trucks and it puts a lot of stress on the end links.

[SSninja]

I eyeballed the sway bar end link tab on the control arm while taking pics today, and it seems to line up reasonably well with the sway bar.

I'll let you know once I actually bolt it all up.


Here's a picture of one of the shocks as well as my attempt to get photos of the bushings on the LCA that I have yet to install.

May be hard to see, but the bushing is a little wider than the sleeve. Does it need to be trimmed down?

https://static1.pt-content.com/images/noimg.gif

https://static1.pt-content.com/images/noimg.gif

https://static1.pt-content.com/images/noimg.gif

https://static1.pt-content.com/images/noimg.gif

[jpgolf14]

I would go with the strut shaft mounted bump stops. I would not want to 3 point bend the a-arm.

Here is a good source for bump stops.

http://www.ground-control-store.com/products/description.php/II=10/CA=1

John

[exwestracer]

Slide the sleeve out and see how it fits in the frame brackets. If it's much shorter than the space between the brackets then longer sleeves are the answer, not trimming more off the bushings. That sleeve should really be a snug fit between the plates to keep everything square when you tighten it all up. I'm know I'm splitting hairs here, but I always like to get this stuff right when I assemble it. It just makes tuning so much easier when you don't have 99 problems to fix first...

[exwestracer]

Oh, and I'm not sure about the shaft bump stops on those Bilsteins. I'm used to seeing a solid top piece on the shock body. Someone else may know for sure, but I'd be a little concerned about punching that top plate down if the stop bottomed hard on it.

[MIKE67]

Ray, you are correct. Most Bilsteins use a captured snap ring to retain the end gland. You compress the end gland, then you can see and remove the snap ring, then the end gland shoots out (if you haven't bled the pressure). A few have a second snap ring to prevent the end gland going too far down the bore, but still relying on the nitrogen pressure to hold the end gland to the outer snap ring.