Finally - Narrowed trailing arms for IRS

Very nice!

Good to see someone set up for this modification again! A 7" Fuchs alloy (with a 205 or 215) fits nicely against the stock spring plate (the sidewall will hit the block on an adjustable spring plate) with beetle drums. If you're going for the wheels/tires being tucked in as far as possible you'll probably have to replace 1 spring plate bolt with a lower clearance allen head bolt (to clear the tire sidewall) and you may have to cut back the bump stop near the top of the shock.

Kevin's work looks very similar to the way my friend Bruce (here in the Vancouver area) did it in the late '80's/early '90's. Check out the June '94 Hot VW's for an in-depth look at how it's done. Al

Good info ALB. I plan on documenting the install, save for the blood and gore shots. Got Disc brakes in the back and was planning on the 5.5 Empi Fuchs or wide five aluminum wheels.

Ahhh.. the disc brakes explains the extra 1/2". If you put the Fuchs copies on it and use original (or original style) Porsche cap nuts, fyi stud length sticking out of the hub is 30 mm.

Is that going to work?

What does Kevin specify for Axles?  Some stock VW length or do we need custom length versions?

Gordon,

Mango smoothie (Paul) gave me the original info and Kevin confirmed. Just need the left axle for a Type 3 Automatic IRS. They are shorter than the Type I. Buy two of them! I believe Moore parts over here in SoCal has them and a general search will give a dog selection. Kevin was quoting $500 plus your cores.

Brian

RacerX posted:

Is that going to work?

Is what going to work?

Sorry, The stud length you were mentioning ...

My friend Bruce said that's what the stud length was sticking out of the hubs on a car with Fuchs he measured. Too long and the studs hit the ends of the lug nuts. Too short and there's not enough thread engagement.  And when you press the studs in make sure that the non threaded part that goes into the hub doesn't protrude and hit the threads on the nuts.

Got it. Thanks for that. 

Brian

Is that 1.5" each side for a total of 3" - or 1.5" total?

Please take pictures with a ruler before and after.

Hey Wolfie,

1.5” per side. I haven’t found anyone with a Coupe who has done this. Mango Smoothie has always been my reference point. Gonna look similar I hope. Yes, I plan on taking many pics. I wanted to let the SOC group know that there are sets sitting on the shelf waiting for new owners. My wait was a good 8 months due to production runs going on at Coolrydes with their other products. I will have a good set of stock IRS arms and axles available afterwards. 

Brian

i remember this step VERY well as i had the suspension in/out/re-welded many times to get the caster just where i wanted it.

my only other $0.02 is to undo the body/pan bolts and many sure it's dead in the middle when you are talking mm's clearance. (undo - loosen, measure via back spacing, rinse / repeat until the chassis and body are perfectly centered)

You know, I had forgotten about those Type 3 automatic, driver side axles being shorter because of the bump-out of the transaxle on that side.

How the hell did you ever remember that??

Mango Paul is scary smart. Just reviewed his build photos again. If I had to learn and remember half as much as him, just think of everything I would have to forget to make room ...

Gordon - as with pretty much my whole build... internet.  i was looking through an empi spec book for drive shafts (in my free time LOL) and saw the different lengths.  i saw the trailing arm design concept (same pic above - same i did too) and the rest is history.  i did cut my bearing carrier completely off so i could factor in how low i was going to run.

Brian - don't sell yourself short.  I'm just a regular guy who is passionate about this kind of stuff.

Gordon Nichols posted:

How the hell did you ever remember that??

He must not have his brain filled with all that old now useless computer stuff like the Hollerith Code, JCL and Assembler language. I sure wish I could do a selective brain reformat and gain back a few gig.  I'm not even asking for a terabyte.

WOLFGANG posted:

Assembler language. 

crawls into corner, sitting cross legged, staring at the floor...  [Shudder]

begins to rock to and fro...   mumbling incoherently...

I had a professor who could converse fluently in hexadecimal.   He scared me to death.

I assign a project number to each of my architectural projects.  Typically, this is something like 1805 for the 5th project of 2018.  This may lead to people making judgments, like "Gee, it is the end of September and Mike has only had 5 projects."

So, for many years I have used hexadecimal project numbers.

Ah, the golden days of programming.  A smart guys with good problem solving skills could take the simple (crude) tools and do just about anything.  Now you have to get specialized training in about 4 million different complex tools to do anything, and it has more to do with a voluminous memory than creativity.  Yeah, computers do a thousand times more, but they need a thousand times faster processors and a million times more resources to do it.  Kids coming out of school now with computer science degrees are clueless about managing resource utilization and being efficient.

You kids get off my lawn!!!

EDIT: And by the way, I like assembly language!

I got my first computer in 1978.  The manufacturer went out of business 6 months later.

So, I had to learn how to program it and repair it.  I even figured out how to make modifications to the motherboard.

It had 64k of memory which was an astounding amount at the time. A lot of people had 4k to 16k. 

I worked in languages like Basic, Fortran, and Pascal.  I even did a little work with assembly language when speed was important.

This is when I learned about hexadecimal numbers.

Lane Anderson posted:

EDIT: And by the way, I like assembly language!

I KNEW there was something about you I didn't like.

You are truly the ONLY one in the universe that likes it.

" Check out the June '94 Hot VW's for an in-depth look at how it's done. Al"

@ALB can you yodal a link to get a copy to read that article...  

WOLFGANG posted:

Gordon Nichols posted:

How the hell did you ever remember that??

He must not have his brain filled with all that old now useless computer stuff like the Hollerith Code, JCL and Assembler language. I sure wish I could do a selective brain reformat and gain back a few gig.  I'm not even asking for a terabyte.

Hey, One brain cell can be made to grow into a Supercomputer  

In 1984 I bought an MAI basic4 mini computer, from Tustin California.  20 meg HD I forgot if it had 16 mb of ram... $40K C$, a few years later $20K for 20megs more.   Interpretative basic, it was my start with a bit of basic coding.  Those were simpler days for sure.

DannyP posted:

Lane Anderson posted:

EDIT: And by the way, I like assembly language!

I KNEW there was something about you I didn't like.

You are truly the ONLY one in the universe that likes it.

I wouldn’t want to do it exclusively, but it’s fun because it really requires imagination.  Most of the time I prefer C or C++. I like to keep the layers of unknown stuff between me and the machine at s minimum.

...defragging the hard drive...

IaM-Ray posted:

" Check out the June '94 Hot VW's for an in-depth look at how it's done. Al"

@ALB can you yodal a link to get a copy to read that article...  

I think I already have it scanned into my computer, Ray; in a previous discussion about narrowing rear suspensions (2? 3? years ago???) I seem to remember sending it to someone. I'll just have to spend a little time looking for it. If I haven't posted it by the end of the weekend feel free to remind me. Al

I know when I need  to restart and can attach photos to my emails ….yippee Kyea!

@IaM-Ray- here you go-

With Bruce's method the bearing housing is cut free and moved inward; probably a little more work than Paul's trailing arms (although I'm sure Paul will dispute that!), but (for those who care) you have to look a little closer to tell what's been done as the arms themselves don't look modified (at first glance). Both achieve the same end and I doubt if there' any strength difference.

My apologies for the upside pages- it was the first time I'd used the scanner. I think you'll be able to spin the pages- 

Note- Just noticed I cut the bottom off of page 2- it should read-

Left- cut out a "D" shaped piece of 3 mm thick steel and weld it to the trailing arm between the bearing housing and the spring plate mounting tab. This provides clearance for the backing plates or brake rotors.

I'll check pages 3 and 4...

Page 3 top- Right- another angle of the modified trailing arm shows how the bearing housing has been moved in. An additional gusset has been welded on the inside of the trailing arm to the bearing housing. You can see this one on the right side of the trailing arm.

Page 4 is good.

Paul's method- 

Thanks for posting it, I got a copy.  Is it being done by anyone outside of the few?  I often wondered why this was not being done to allow more tire size on the rear.  We had special rims widened "inward" on my last IM.  It seems you could do to have this done or produced by some manuf.... they do shortened beams... 

I don't know why it's not done more often; I guess because it's quite involved. With an irs it is the way to get the most tire under the rear, though, and if you look at the steady progression of wider tires under the rear of 911's through the years there is a benefit. A few different shops have done them over the years but I guess there's just not enough demand to keep shortened irs arms in stock.

My guess is that few would choose it at first and many have modified the wheels but seriously it would be something builders could offer but mine did not mention it on my builds

WOLFGANG posted:

Is that 1.5" each side for a total of 3" - or 1.5" total?

Please take pictures with a ruler before and after.

Really? Will this move you along faster?

(Cory here, on Jeni's computer)

For my mental repository - for my next build!

ALB posted:

I don't know why it's not done more often; I guess because it's quite involved. With an irs it is the way to get the most tire under the rear, though, and if you look at the steady progression of wider tires under the rear of 911's through the years there is a benefit. A few different shops have done them over the years but I guess there's just not enough demand to keep shortened irs arms in stock.

my guess is the rear wheel alignment.  i found even the first small tack weld put the geometry out a few degrees.  IIRC, i had to set the rear caster where i wanted it, the grand off another 1-2 degrees (pivot from the first tack weld)... then do the first tack weld.  dont know if that made any sense, but even with cooling (outside) checked, i had to factor warping.  not hard, but LOTS of measuring.

Ok! The arms are on. Whew, that was a lot of work. Besides the benefit of the wheel clearance, I was able to change out all the bushings, bearings, seals, CV joints (With the new shortened axles) and pivot bolts. The back end of the car is properly squared away. Important notes: You will want to use the stamped steel disc brake bracket instead of the cast one ( For clearance purposes). You will also have to do some clearance work on the end of the perimeter frame for the engine compartment because you have just brought everything in by 1.5 inches and when the rear wheel alignment was done, the arms were slid all the way back on the spring plates. Now, I am not the best photographer, but hopefully you get an idea of the gratuitous room available for a nice set of wheels.