[ZeGermanHam]

Hi all,

I'm getting ready to bolt on all of my new suspension and rear end parts to my freshly refurbished '66 GTO frame. I'm installing a new Quick Performance 9" rear axle which came with rubber upper control arm bushings preinstalled.

However, my UMI State 3 suspension kit also came with polyurethane bushings for the diff. I'm debating on whether it's worth the trouble of pressing out the rubber bushings and installing the poly bushings.

The rest of the rear control arm bushings are a combination of polyurethane and spherical "roto" joints. The car is being built to handle like a more modern car, but won't be used for autocross. It'll be on 15" steelies with 235/60R15 tires.

Are the rear upper control arm diff bushings a game changer, or are they less impactful than other areas? Thanks!

[Scarebird]

I would stay rubber - poly binds it up too much.

I went all spherical on mine.

[leeklm]

As mentioned, the rubber should be fine. I used the roto joints with adjustable uppers on my 66 and really liked them . Along with reinforced stock lower arms with poly bushings you could do burnouts all day long with no wheel hop whatsoever.

Sent from my SM-G965U using Tapatalk

[ZeGermanHam]

Thanks Scarebird and leeklm. Sounds like I'm unlikely to experience any significant drawbacks to sticking with rubber bushings on the diff. I suppose if for some reason they aren't working out, it's easy enough for me to swap them out for the poly bushings down the road.

[jarretts70]

scarebird, did you fit spherical bushings to the original arms? what bushings did you use?

[pokey1]

going with HR parts and stuff bushings. They are poly but have grease zerks and are grease able so they do not bind or squeak. The stock ones that came in my quick performance rear were really soft so switching.

[Scarebird]

Originally Posted by jarretts70

scarebird, did you fit spherical bushings to the original arms? what bushings did you use?

I used Speedway's Metric 1973-88 bushings. I had to make end spacers for them.

[jarretts70]

Scarebird - So you turned the spacers in a lathe? I like your setup. Good way to take advantage of the not so expensive speedway bushings. I don't have a lathe...dang.

I've got a set or ridetech adjustable upper arms on order. I went with them simply because I could get a good price thru a local shop that is a dealer. They use a spherical bushing @ the frame end. My plan was to find another spherical bushing to use in the axle end of the lower arms. Then use poly in the rear upper location (the ones pressed into the axle). and also the front lower. I figure the mix of spheres & poly should firm things up & still have reasonable articulation.

[Scarebird]

I hope it works for you - I have noted from experts that poly won't swivel like rubber or spherical, your feedback would be quite valuable.

[pokey1]

Here are the new poly bushings I put in..

[ZeGermanHam]

Originally Posted by pokey1

going with HR parts and stuff bushings. They are poly but have grease zerks and are grease able so they do not bind or squeak. The stock ones that came in my quick performance rear were really soft so switching.

What were the symptoms you experienced that caused you to feel the bushings in your QP rear end were too soft?

[pokey1]

Originally Posted by ZeGermanHam

What were the symptoms you experienced that caused you to feel the bushings in your QP rear end were too soft?

None at this time. I have had the old Lakewood ladder bars on the car since 1978. The car has always sat pretty high in the front and back. In about 1998 I was going thru the car again and had the ladder bars off and decided to try running without them. On the street in front of my house I dumped the clutch and the car started to hop severely and before I could get the clutch back in it sheared the teeth off of 1st gear on the main cluster and the countershaft. Put ladder bars back on and never had the problem again. The ladder bars make everything really stiff and the way it was set up there was now way I could get the correct weight transfer I wanted. When I put the quick performance rear end in I put Adjustable coil over shocks on so I would be able to lower the height. I have now put the coil overs on the front and went to lower the car but the ladder bars would not let the back go down. Ca really get no adjustment the way they are set up. Si I decided it is time for them to go and now trying HRpartsnstuff sway bar. While under the car I could see that just sitting the upper trailing arms on the diff were really squishing out already and was told that is typical because of how soft they are. I order to keep consistent driveline angles when dropping the clutch It made sense to me to make the rest of the suspension components more rigid so that why I decided to try this. Car is now down about 3 inches all around from the picture. Haven't had a chance to try it yet.