Do 87 trailing arms work on a 72???? and other ?????

[herman maire]

Just wondering.
I know somebody who is parting out a 87 coupe and im thinking I may be able to use the rear trailing arms and some other parts.

Is this a good year to use ?? Does it require mods VS the 74-75 arms??


A few questions ( also please tell me what a fair price is to pay , I have no clue)

1- for both rear arms and set up including hubs, brakes,e-brake ect...???

2- Brake Booster, is it worth it the trouble ???

3- A/C blower and condensor - Is this a worth while upgrade??

4- Front suspension- Any advantages over my 72 gear???

What else would be a good upgrade for a 72 coupe????

[Bill Verburg]

im thinking I may be able to use the rear trailing arms

No, '86 and earlier yes

1- for both rear arms and set up including hubs, brakes,e-brake ect...???

No, the brakes are all wrong unless you have Boxster fronts

Brake Booster, is it worth it the trouble ???

No, unless you have other chages to the brakes

4- Front suspension- Any advantages over my 72 gear???

Yes, the front brakes are a nice inexpensive upgrade.

[gestalt1]

i put 87 trailing arms on my 73 but i had to use the carrera halfshafts (the ones with the stub axle on the end) and change to fine spine 108mm output flanges on the transmission. i was changing the differential anyway so i got a fine spline type. i figured this out the hard way - buying parts until it worked method.

[herman maire]

Originally posted by Bill Verburg

Yes, the front brakes are a nice inexpensive upgrade.

Thanks Bill.
I was ready to have the rear arms shipped. I had no idea the 87 were different.

So the rear end from the 87 is pretty useless for my 72.

As for the front end, I am going with the 993 brake set up on the 72 like you have. Other than the caliper difference between the 87 and 72 are they basicaly the same??
( control arms, struts hubs ect..) Also what are they worth as a set??

Anything else worth getting off the 87??

[herman maire]

Originally posted by gestalt1
i put 87 trailing arms on my 73 but i had to use the carrera halfshafts (the ones with the stub axle on the end) and change to fine spine 108mm output flanges on the transmission. i was changing the differential anyway so i got a fine spline type. i figured this out the hard way - buying parts until it worked method.

Thanks for the reply
I dont plan on changing my diff to get the fine spline type is there any other solutions or is this mainly why it does not work.

Also how much should I pay for a pair of complete Alu trailing arms and how much are the adj spring plates??

[gestalt1]

the output flanges on the 72 915 are the 4 bolt, 2 pin type. i think you could buy the carrera halfshafts, remove the inner cv joins and replace them with cv's for a 72. the carrera inner cv's are the 6 bolt type but i think they are the same diameter. there is something different about the aluminum casting and the earlier stub axles scrape the inside of the aluminum. the carrera stub/cv joint is more compact. i paid about $400 for my 87 trailing arms with bearings.

[Bill Verburg]

As for the front end, I am going with the 993 brake set up on the 72 like you have

I have 993RS brakes on both of my cars.

For 993 fronts you will want 993 or 965 rear calipers.

The '72 rear has the same 3" mounts as all the other 911s thru '89

the '86 and earlier rear suspension can be transplanted in easily if you want aluminum arms.

'77 - '86 have the height adjustment.

[Britain Smith]

I did this swap between a '69 and an '87. Here are some pictures that I took. I haven't gotten to the part with the halfshafts...it is a work in progress.

-Britain

[Spede]

MAN! Does it pay to be friends with the Wevo guys.

That stuff looks awesome!!!

[herman maire]

Britain thanks for the pics. Car looks great.

Can anybody confirm this but this is what I understand.

1-If I use 86 and earlier traling arms I can use my stock 72 CV joints , brakes and E-brake set up.

2- If I were to use the 87 set up I would need the outer carrera CV and my 72 inner CV. ( I still dont know why the rear carrera brake set up wont work ) Is it because of the valving???

If I remember, I read that they changed the valving to a higher % to the rear with 3.2 Carrera's to stop the front end front premature lock up. Any truth to that????

I guess the only reason I am considering the 87 set up is because I can get it for $150. From the sounds of it its probably cheaper in the long run to just get the 86 and earlier set up.

What do you guys think??

Again thanks for the replys for helping me out.

[arrivederci]

Originally posted by herman maire
Britain thanks for the pics. Car looks great.

Can anybody confirm this but this is what I understand.

1-If I use 86 and earlier traling arms I can use my stock 72 CV joints , brakes and E-brake set up.

2- If I were to use the 87 set up I would need the outer carrera CV and my 72 inner CV. ( I still dont know why the rear carrera brake set up wont work ) Is it because of the valving???

Are the '87+ trailing arms themselves any different from the '84-'86? I don't think so...its the spring plates that are different due to the G50 tranny and the different rear torsin bars.

The other difference that I'm aware of with trailing arms are the sway bar mounts. The '74 and '75 have the same style mount as your '72. The later bars (not sure when the change occurs) use a later style sway bar mount.

Finally, as has been said, your '72 stub axles work with your 4-bolt 2-pin CVs. You'll need to transplant the stub axle from you '72 into the aluminum trailing arms. Or, build up a custom CV with 4-bolt 2-pin inside and 6 bolt outside. The later stub axles ('85+, I think) use larger bolts too (10x50 vs 8x50). See the pelican catalog for details on the bolts.

On my car, I re-used the stub axles from my '72 in later aluminum trailing arms (not '74 or '75). I went with aftermarket sway bars so the sway bar attachment wasn't important.

[herman maire]

Originally posted by jpinkert
.
Finally, as has been said, your '72 stub axles work with your 4-bolt 2-pin CVs. You'll need to transplant the stub axle from you '72 into the aluminum trailing arms. Or, build up a custom CV with 4-bolt 2-pin inside and 6 bolt outside. The later stub axles ('85+, I think) use larger bolts too (10x50 vs 8x50). See the pelican catalog for details on the bolts.

On my car, I re-used the stub axles from my '72 in later aluminum trailing arms (not '74 or '75). I went with aftermarket sway bars so the sway bar attachment wasn't important.

Thanks Josh

Did you run into any trouble transfering youre stub axles into the later Alu trailing arms?? The 87 arms should be the same deal as what you dealt with right??

I really do not want to get into custom CV's. Its just not worth it. I can handle tranfering my stub axles, thats about it.

Did you use the 72 Hubs or the later Alu ones on youre set up??

Is there a problem using the 87 hubs with my 72 stub axles???

I am also going with big aftermarket sway bars so would this pretty much cancel out any problems as to the sway bar situation with the 87 arms set up on a 72???.

If you have any pics when you tranfered the stub axles, it would be interesting to see.

Thanks again Josh

[arrivederci]

I don't remember having any trouble with the stub axles. And I'm not aware of any changes in the trailing arm design over the carrera years ('84-'89). The only change that I know of occurred in the earlier years when they modified the sway bar mount.

I used the later hubs that came with my trailing arms. I 'think' they're needed because the rear wheel bearings are different (I did this over a year ago and don't remember all the details).

In summary - older stub axles, newer hubs, newer trailing arms. As a while you're in there thing, think about adjustable spring plates, monoballs, and new bushings throughout.

I've got a late 915 tranny that I'm putting in soon that'll have the 6 bolt flanges. I'll be swapping in the later stub axles and then converting my early 915 to use later CVs as well.

[gestalt1]

when i got my 87 trailing arms i put the stub axles in and loosely tightened the nut and i could not turn the stub without getting a metal on metal grind. when i put the carrerra axles in there was no problem. maybe there are different stub axles but i assembled the same as what was on the original 73 steel trailing arms. it seems strange that porsche would change the casting in 87 - they were already working on the next generation chassis.

[arrivederci]

Originally posted by gestalt1
when i got my 87 trailing arms i put the stub axles in and loosely tightened the nut and i could not turn the stub without getting a metal on metal grind. when i put the carrerra axles in there was no problem. maybe there are different stub axles but i assembled the same as what was on the original 73 steel trailing arms. it seems strange that porsche would change the casting in 87 - they were already working on the next generation chassis.

Pelican lists the trailing arm itself as the same part from '78-'89.

http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_SUSshk_pg10.htm#item46

The axles were larger from '85'-89.

http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_SUSaxl_pg2.htm#item8

Maybe the 6 bolt 10x50mm hub and stub axle was also a different setup. The wheel bearing is the same from '74-'89. Remember that the G50 tranny was used from '87+, so there were some significant changes in '87. But from everything I've seen, the '87 trailing arms will work if used with the correct stub axles and hubs. The exact year of the incompatibility seems to be around '85 based on part differences in the rear suspension/axle assembly.

[randywebb]

Use the PET and see if the P/N'S are the same -- I posted some p/n's a couple years ago but that was for earlier apps.

[tom1394racing]

I did the Al trailing arm upgrade on my '73. I used the '74-'77 trailing arms. I also used the hubs and stub axles from my original '73 arms to ensure a match with the 915 output flanges and CV joints. The early hubs and stubs will fit into the '74-'77 arms.

This is a much easier way to go than trying to use the later Carrera Al arms. These require the later Carrera style stub axles that will not be compatible with your CV's or your 915 output flanges.

I think you would run into the same problem if you tried to use the arms from a '78-'83 SC. I don't believe that your original stub axles will fit on the SC arms.

[78targa]

Remember that if you swap hubs you will most likely destroy the bearings. I'm not even sure how you could get the hubs out without doing that. So add $120 to the cost of the swap. As far as trailing arm differences, I just parted out a '77 and an '81 and the traling arms were the same with the exception of the swaybar mount.

[tom1394racing]

Absolutely plan to replace the bearings.