UMI Releases New Product: Bolt In Rear Coilover for the 1964-1972 GM A-Body
 

Here's a few installation pictures of our new bolt in rear coilover kit that features control arm relocation. Kit works best for 1-3" lowering, although if stock height is desired we can substitute for a longer shock. Also you'll see some good pictures of our rear shock tower brace installed.

http://umiperformance.com/catalog/im...-XXXab_LRG.jpg

http://umiperformance.com/catalog/im...-XXXad_LRG.jpg

http://umiperformance.com/catalog/im...-XXXae_LRG.jpg

http://umiperformance.com/catalog/im...-XXXaf_LRG.jpg

http://umiperformance.com/catalog/im...-XXXai_LRG.jpg

http://umiperformance.com/catalog/im...-XXXak_LRG.jpg

Awesome...I was looking at the Viking setup for the rear to match my fronts with umi control arms and you guys took it to the next level....hope to be on the shipment list soon

With this kit, am I able to run 20x12 with 325-335 tire?

This is a tough question with out trying. I am going to say yes most likely but depending on back spacing I wouldn't be certain.

With the wheels on the car you could e-mail us some pictures and we could know by that as well.

Thanks!

I am very interested in how wide of a tire I can run with this kit on a '67.

Right now I'm staring down putting in mini tubs from ABC Performance to get a 325 - 335 tire in. If it's possible with this kit, it would save me work.

If you can answer either way, I'd be interested.

:cheers:

The LeMans happened to be on the lift this morning.

If you look at post 2 above, you can see there is a ton of room between the bracket and the tire. I verified with my own eyes and know for sure that a 335 would fit with plenty of room to spare.

https://umiperformanceinc.files.word...67-2.jpg?w=960

https://umiperformanceinc.files.word...66-2.jpg?w=960

ramey

Ramey,

I see there are three locations for the LCA to mount at the rear end. Can you elaborate on that please?

Andrew

Certainly.

We always have the factory attachment point available. As you lower the car, the trailing arm can start to point uphill toward the rear. The top hole in our bracket allows you to get that arm back to a slight downward angle toward the rear. If you go super low, you can use the next hole to restore that angle. That's the simple explanation.

In side view, you can process the angles of the arms and come up with an instant center point somewhere in the front of the car (or within the confines of the interior). Simply a point in space. Knowing where you want that point in space is a big advantage and therefore having factory plus three options to tune that location is popular. Our brackets allow you to do that.

Without going into too much analysis at the moment, lowering the trailing arm normally improves forward traction but sometimes at the expense of a few other things like brake hop and excess roll steer...

ramey

So basically this allow you to tune the anti-squat properties...

Andrew

Haha, that's it exactly.

Ramey,

Another question if you don't mind...

Do the shocks themselves act as travel limiters in rebound? Can they handle that?

Andrew

They aren't supposed to under normal circumstances. With that being said, the occasional high grip auto-x car can get out of sequence enough to lift an inside rear tire by topping out the shock. It doesn't seem to hurt anything when done on occasion. Each manufacturer has a different philosophy and I know some shocks are more delicate than others.

That's why I was asking...I know the stock suspension uses the shocks as travel stops and to keep the springs in place. Obviously this isn't a concern with coilovers, but I know some shock manufacturer explicitly state that bottoming the shock in compression or rebound will kill it in short order...

Would spring selection be better done by knowing the rear weight balance?

Andrew

When designing a coil for the A-body for instance, we know some of the general parameters and don't deviate much from tried and true situations. For example, 130 lb/in works pretty nice. I can work in the 100 lb range safely and the 150 lb range safely. Beyond those numbers takes different tuning and balancing. Same goes for stroke lengths on the shocks. We follow the 60/40 rule where we like to have the shock shaft between 40 and 60% of its travel at ride height. Too much one way and we top or bottom the shock out. We also want to stay in normal situations like aprrox 5" stroke. 4 is a little low. 3 is really low. Extension is a little more forgiving where we can use 6-7 ish.

All of our stuff comes from driving, trying, re driving, re trying, racing, driving, testing then releasing product. Usually its' good, sometimes even the best plans need tweaked...

ramey

Thanks!

Andrew