dizwiz24

C-beam and driveshaft is removed on both cars.

my supercharged 1993 vert , with banski rear rod end suspension AND polyurethane batwing bushings D44 snout can be rocked up and down with the c beam and driveshaft removed.

I remember this being ‘true’ when i first did the Banski rod end rear suspension and put polyurethane batwing bushings into the D44 batwing. I remember being ‘surprised’ the amount of movement I could get by pushing the D44 snout up and down. I could understand why people have added ‘pinion’ snubbers. I assumed this was all normal.


now that i have bought another 1993 6spd, that also has its c-beam/drivesshaft out. I performed the same test and to my ‘surprise’ the d44 diff snout on this car doesnt move up and down at all with the same force applied Heck, it probably has rubber (not even poly bushings) in the batwing. The rear suspension on this car has stock parts (not rod-ends)

any idea what is going on here?

dizwiz24

i didnt really expect a lot of replies, but here is what i think is going on

the problem on car #1 (excess movement of the diff snout with the c beam OFF) is likely not the banski rod ends but the pintop rear spring mounts i installed many yrs ago. Its possible they me be allowing some additional movement in the rear spring bushing vs. rear knuckle assembly

car #1 has them. Car # 2 does not

im going to put regular polyurethane rear spring mount assembly on and see what happens

Car #1 which has excess diff snout play when pushing it up/down

Car #2 which does nor have as much diff snout movement

'78CorvetteS.A.

I don't think your spring mounting has anything to do with it. I would think it's because on the stock suspension '93, the rubber in the bushings is molded (bonded) to the inner sleeves...when trying to articulate the suspension by hand, you are having to overcome the resistance of the rubber to flex/twist in every bushing....you need the weight of the car and the external resistance of the road to accomplish that. On the Banski/poly set up, the heim joints are designed to articulate without resistance and on poly bushings the sleeve is pinned when torqued down, but the bushing is not bonded to the sleeve and thus, is allowed to rotate with far less applied force....you're not stretching or compressing the bushing nearly as much. Your two '93s are reacting exactly as I would expect! This is why you've seen the thread debates about some guys liking the heim-joints and other guys feeling it makes the suspension feel loose....and some of the guys feeling that the "bonded" factory bushings need to be there, as there resistance to stretch/compress is integrated into the rear suspension design....and others who think the opposite! Just my thoughts on it, right or wrong???👍

dizwiz24

great analysis of my bad explanation . It seems you understand exactly what I am talking about.

i went back in and did the same experiment and noted car #2 (1993 with stock rear suspension pieces) does indeed have SOME movement to the diff snout. (I think I made it out like it has none). My point if that car # 1 (with banski suspension pieces and polyurethane bushings) has some more / which is opposite what I would expect

I am interested in this phenomena because
I had some wheel hop issues (at drag launch) on car #1

any ideas on how to fix this ?

86C4vert

I agree on the twist factor - seems like a non bonded bushing would be more likely to twist easily.

My other thought is that maybe the natural rubber has stiffened with age and is as stiff or stiffer than the polyurethane.

dizwiz24

Just for kick, i replaced the Banski rod-end rear camber rods with the old stock 1993 camber arms (prob age hardened bushings).

there is less ‘snout’ movement of the diff now and it is more like that of car #2.