Rear Control Arm won't Fit with New Bushings

[S30Driver]

I am helping my nice retired neighbor out with his restoration of his series 1 240z.  Paint and body all complete,  assembly has begun.  Car is on rotisserie.

We are assembling the rear suspension and at the point of installing the new spindle pins and ......... can not get the lower control are to line up with the hub assembly to slide the new pins in.  With the new poly bushings installed on the passenger side, the gap between the control arm is about 4 mm too small to fit in the hub assembly and get the pin in.  I measured the driver side and it looks like it will fit ok on that side.

Has anyone run into this?  Am I missing something obvious?  At a standstill until this is resolved.

 

[Zed Head]

I recall past discussions about it.  Sometimes we've gone pretty deep in to which ends goes where and how much movement there is at that joint and whether or not the two surfaces ever contact.  Anyway I think that that urethane would just get squeezed and destroyed  when the suspension moves.  It's not meant to be a bearing surface.  I think that there's a thread somewhere where people just decided to trim it off.

Here's one thread I found that shows how the Nissan part has no rubber in that joint.  Separation is controlled by the strength of the rubber in the bushing itself, but if the rubber deflects the two metal surfaces will contact.

Number 57 - http://www.carpartsmanual.com/datsun/Z-1969-1978/axle/rear-suspension

http://www.carpartsmanual.com/datsun/Z-1969-1978/axle/rear-suspension/57

 

Edited March 13, 2021 by Zed Head

[S30Driver]

Thanks ZH.    We will see if we can trim those bushings tomorrow and see if it will fit together.  

[Captain Obvious]

Yeah, that's not a new issue. The two choices are trim the bushings down, or jam it the heck together by compressing the urethane. Putty knife comes to mind...

I don't consider either of those a fantastic solution, but given those two, I would trim just enough off the bushings so that jamming them together doesn't make you wince.

[crayZlair]

Just an FYI, when you go to install the new spindle pin, be aware that the notch is not in the middle of the pin. Ask me how I know! 🙄

[S30Driver]

10 hours ago, Captain Obvious said:

I don't consider either of those a fantastic solution, but given those two, I would trim just enough off the bushings so that jamming them together doesn't make you wince.

I agree.   Harold has a big vertical belt sander in his shop.  Might use that to trim down the bushing ends as small amount as necessary to fit.

[S30Driver]

9 hours ago, crayZlair said:

Just an FYI, when you go to install the new spindle pin, be aware that the notch is not in the middle of the pin. Ask me how I know! 🙄

I'll pay attention to that!   Would hate to have to pull those new pins back out and turn them around ...

[foosman]

For my urethane bushing install, I used a floor jack to spread the "arms" of the control arms ever so slightly, but I think they were off by less than your 4mm.  Could also vary by which urethane bushing set you're using - I used the set from Motorsport Auto (black).

[Jeff G 78]

I just went through this last weekend on my 260Z race car.  Start by making sure the bushings are fully seated.  I used a big clamp with a socket on the outboard side so the steel sleeve wouldn't stop the compression.  This also makes sure the sleeve is slightly outboards.  Once both are compressed as much as possible, grease the bushings to help the knuckle slide in and place a VERY thin putty knife on each side and then work on getting the knuckly into place.  Mine were very tight, but after a few attempts, they both went in.  Getting the spindle pins in was a pain in the arse too.  Everything has to be lined up perfectly before the pins will go all the way through.  Finally, rotating the pin to the ideal position for the wedge bolt is a bit tricky, but not too bad.  Good luck!

[foosman]

More discussion on the issue, including the "floor jack spread" approach.

 

[Racer X]

Lubricate the bushing flanges and the mating surfaces on the hub with silicone grease and use two thin putty knives to wedge it in like Jeff did. Clamp the lower control arm in a vise, and have your buddy hold the putty knives. Tapping with a plastic coated dead blow sledge helps persuade it,. A couple of long, tapered line up bars helps get things the last few millimetres, and lined up for the pin.

Edited March 14, 2021 by Racer X

[Zed Head]

Not clear why a person would distort the line of the cylinder, the three passages, that the spindle pin passes through in an attempt to make a poorly designed aftermarket piece of polyurethane fit.  These aftermarket urethane parts sellers just looked around the car and made shapes that looked similar to any rubber that they found.

I'd focus on modifying the aftermarket parts to fit the original design of the suspension components.  The Nissan engineers put a lot more time and effort in to that than the PU parts guys did designing those little PU bits.

Edit - No offense intended to any opinions ventured so far.  I've just spend some time wondering "who designed this thing" in the past.

Edited March 14, 2021 by Zed Head