69 Aluminum Rear Trailing Arm Advice

[mwg968]

I have a 69 Coupe project coming to the point of needing suspension.

I've got the stock steel suspension and am planning to have it reconditioned and reinforced a la RSR to go along with the rest of the car's general strengthening.

However, I am also going to be running an Aluminum engine case and transmission and am aware I'm adding a good bit of weight where you really do not want anymore.

It seems the best way to reduce weight in this area would be to swap out the trailing arms for Aluminum units. I've read that it is possible but a real PITA and requires some modifications.

My questions are for those brave souls who have done it.

1. Are there any downsides to the aluminum vs the steel? Besides being weaker? (I'm not building a Safari car so not a huge concern)
2. Anyone know what the actual weight reduction is?

A little extra incentive as I shake the tree of knowledge. I've got some free parts I'll be listing in the next days and if you give me some answers you get first crack at the pile!

Thanks for your help,

[tom1394racing]

I have been using the early Al trailing arms on my '73 RSR clone for 20+ years. No issues. I have a pair coming up for sale if you are interested.

[Nickelplated5s]

Interesting idea as I've got bushings for mine sitting on a table along with the ER tools. Tom, will those fit in your AL arms? Will they fit a SWB or are they different?

[tom1394racing]

I have this pair of the early Al trailing arms ('74-'77). The weight difference between these and the steel arms is 14.8 lbs for the steel arm and 11.4 lbs for the Al arm. 3.4 lbs per arm or 6.8 lbs for a pair.

[tom1394racing]

Interesting idea as I've got bushings for mine sitting on a table along with the ER tools. Tom, will those fit in your AL arms? Will they fit a SWB or are they different?

The trailing arm bushings are the same SWB - 3.2 Carrera.

[Nickelplated5s]

PM to Tom.

[Chris Pomares]

My understanding is only 72/73 cars are close to drop in. On 69 to 71 cars the alignment inside the tube to the upper shock mount might need attention. Or run without the top shock cover.

[Nickelplated5s]

Thanks Chris, mines a 67.

[tom1394racing]

My understanding is only 72/73 cars are close to drop in. On 69 to 71 cars the alignment inside the tube to the upper shock mount might need attention. Or run without the top shock cover.

Chris

Yes, I think you are correct. The easy solution is to run w/o the dust covers on the 69-71 cars.

[mwg968]

Chris

Yes, I think you are correct. The easy solution is to run w/o the dust covers on the 69-71 cars.

Thank you all very much for the input. It seems like some work for ~7 lbs but then again, that is unsprung pounds taken off the correct part of the car... decisions.. decisions... I will not be running heat exchangers so perhaps less concerns with interference.

Would my 69 E-brake carry straight over or are there any other issues besides the annoying but seemingly surmountable clearance?