Show full size 924Board.org
Discussion Forum of 924.org
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
 Technical FAQ924 FAQ (Technical)   Technical924 Technical Section   Jump to 924.org924.org   Jump to PCA 924 Registry924 Registry

Illustrated Guide to 5-lug Conversions
Goto page 1, 2, 3  Next
 
Post new topic   Reply to topic    924Board.org Forum Index -> How-To
View previous topic :: View next topic  
Author Message
ideola  



Joined: 01 Oct 2004
Posts: 15426
Location: Woodstock IL

PostPosted: Tue Oct 21, 2008 3:07 am    Post subject: Illustrated Guide to 5-lug Conversions Reply with quote

Since I've been working on collecting the bits for several 5-lug conversions recently (two cars for myself, and at least six other board members), I thought it might be helpful to document the options available for converting. I do NOT profess to be an expert on these conversions, as I have yet to execute one on a running car, so this should be viewed as a good starting point, and hopefully some of the more knowledgeable PET experts can post corrections and clarifications in THIS thread, instead of having them scattered all over the forum.

The first thing to point out is that when performing a conversion, you should acquire some of the parts new, while many of the parts can be acquired from a donor car. To that extent, I am NOT going to cover all of the available options in detail regarding the new parts (i.e. brake pads, brake rotors, rebuild kits, or aftermarket calipers such as the Wilwoods). My intent here is two-fold: provide a comprehensive list of parts required; and discuss some of the options, dependencies and nuances with the donor components.

The second thing to point out is that there are two fundamental options in terms of donor components: what are commonly referred to as "steel-based conversions" and "aluminum-based conversions". There are differences between the two, so I am going to provide two separate postings covering each one in detail.

{EDIT}
For a complete discussion of evaluation criteria when considering which 5-lug components to source, see also: SUSPENSION, BRAKES, WHEELS & TIRES (Performance Upgrades)

As noted in the above-linked Performance Upgrade post, the most critical aspect of deciding which 5-lug components to source has to do the differences in spindle geometry. The hub and spindle metrics are all recorded in a Google Docs spreadsheet. See also this thread: Solving a Hub and Spindle Mystery.

KEYWORDS: 5 five lug four wheel disc brake suspension conversion swap steel aluminum alu ali trailing arm spindle hub caliper four pot 4 pot
_________________
15 981 GTS | 04 955 Turbo | 88 924S SE | 82 931 (x2) | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod (x2) | 78 Poli-Form | 78 Limited Edition | 77 Martini


Last edited by ideola on Fri Dec 05, 2008 11:17 pm; edited 3 times in total
Back to top
View user's profile Send private message
ideola  



Joined: 01 Oct 2004
Posts: 15426
Location: Woodstock IL

PostPosted: Tue Oct 21, 2008 4:02 am    Post subject: Steel-based 5-lug Conversion Reply with quote

Steel-based 5-lug Conversion
Starting with 1980 931's, 5-lug four wheel disc setups became available, and were carried forward into the 944 platform through 1985½. These suspensions used steel trailing arms and steel front a-arms, hence the moniker. Because the pre-85½ 944's were based on the same setup, the offsets and axle half shafts are identical to the 4-lug rear drum brake setups, so when sourcing a steel-based setup, there is no need to get the half shafts. The minimum list of parts, then, consists of the following:

Donor Components
Front
  • Front spindle and hub (with nuts and thrust washers)

  • Dust shields

  • Calipers & hardware
Rear
  • Trailing arm and rear hub¹

  • Calipers

  • Dust shields

  • Hand brake cable assembly

  • Hand brake shoes, adjusters, and linkages
Other
  • Brake booster and master cylinder
Optional
  • Adjustable spring plates²

  • Front sway bar and hardware³

  • Rear sway bar and hardware³

New Components
From Rasta Monsta's post in Jan 2007:
  • Rotors
  • Pads
  • Wheel bearings and wheel seals
  • SS brake hoses
  • Lug nuts
  • Brake hardware kits
  • Hardline and related tools & hardware to connect at rear wheels

Notes
  1. Technically, you do not need the entire trailing arm, nor do you need the axle stub, as these are identical between the 4- and 5-lug steel-based suspensions. However, when sourcing from a donor car, it's usually a no-brainer to just snag the entire rear trailing arm with the stub axle and hub as an assembly and just swap in.
  2. If your car doesn't have the adjustable spring plates, now would be a good time to add them.
  3. If your car doesn't have sway bars, now would be a good time to add them. Note that essentially ANY sway bar from ANY 924/931/944/951/968 are interchangeable, although some minor fabrication might be required for some of the mounting hardware. Also, be aware that the rates between front and rear should be matched, so sourcing a set from a given donor car would be ideal.

_________________
15 981 GTS | 04 955 Turbo | 88 924S SE | 82 931 (x2) | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod (x2) | 78 Poli-Form | 78 Limited Edition | 77 Martini


Last edited by ideola on Tue Oct 21, 2008 4:37 am; edited 1 time in total
Back to top
View user's profile Send private message
ideola  



Joined: 01 Oct 2004
Posts: 15426
Location: Woodstock IL

PostPosted: Tue Oct 21, 2008 4:35 am    Post subject: Aluminum-based 5-lug Conversion Reply with quote

Aluminum-based 5-lug Conversion
Beginning on 1985½ 944 models, aluminum based suspensions became available. The primary difference was strictly in the rear trailing arm and the front A-arm. The aluminum components save significant weight (note to self: need to weigh the difference...). Also note that the spring plates are different between the steel- and aluminum-based setups, so you MUST source the spring plates if switching to aluminum. There are a number of other model-year-specific caveats and notes to be aware of (see list at the bottom of this post). For simplicity's sake, sourcing from a ~86 944 NA seems to be the most directly compatible donor. The minimum list of parts, then, consists of the following:

Donor Components
Front
  • Front spindle and hub (with nuts and thrust washers)

  • Dust shields

  • Calipers & hardware
Rear
  • Trailing arms, stub axles, and rear hubs

  • Adjustable spring plates

  • Calipers

  • Dust shields

  • Hand brake cable assembly

  • Hand brake shoes, adjusters, and linkages
Other
  • Brake booster and master cylinder
Optional
  • Front A-arms

  • Front sway bar and hardware³

  • Rear sway bar and hardware

New Components
From Rasta Monsta's post in Jan 2007:
  • Rotors
  • Pads
  • Wheel bearings and wheel seals
  • SS brake hoses
  • Lug nuts
  • Brake hardware kits
  • Hardline and related tools & hardware to connect at rear wheels

Notes & Caveats
  1. For the front A-arms, some of the 944/951 crowd actually retro-grade to the earlier steel A-arms because in severe duty applications, the aluminum A-arms have been known to fail. The steel and aluminum based A-arms are identical in terms of geometry, although the sway bar mounts are different.
  2. Also, note that the late 951 (as opposed to the 944 NA) front A-arms are different and require some other fettling (note to self: verify date range).
  3. The late 951 spindles do not have the accommodation for a speedo cable, so if you convert using a late 951 as a donor, you will most likely need to install a wheel speed sensor and convert your manual speedo to an aftermarket electronic speedo.
  4. If you source spindles from a 1985.5 or later 944, you MUST also source the strut housings, as the bolt pattern and flange width on the spindle are different than the early cars.
  5. The axle half shafts are longer in the aluminum based systems, so these MUST be added to your shopping list.
  6. The 951 four pot Brembo calipers from the 951 will not bolt directly onto the NA-based spindles, although the rears bolt up just fine. Consequently, if you want the Brembo's, you will need the matching spindles (which do NOT support manual speedos as noted above), or you will need to fabricate or purchase adapter brackets. Raceboy posted an excellent thread on the topic in Nov 2007.
  7. If your car doesn't have sway bars, now would be a good time to add them. Note that essentially ANY sway bar from ANY 924/931/944/951/968 are interchangeable, although some minor fabrication might be required for some of the mounting hardware. Also, be aware that the rates between front and rear should be matched, so sourcing a set from a given donor car would be ideal.

_________________
15 981 GTS | 04 955 Turbo | 88 924S SE | 82 931 (x2) | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod (x2) | 78 Poli-Form | 78 Limited Edition | 77 Martini


Last edited by ideola on Fri Dec 05, 2008 11:20 pm; edited 2 times in total
Back to top
View user's profile Send private message
Martijnus  



Joined: 29 Dec 2006
Posts: 2020
Location: Netherlands

PostPosted: Tue Oct 21, 2008 9:45 am    Post subject: Reply with quote

you are seriously the man by posting this! Thanks!
_________________
"Rule: Turbo's make torque, and torque makes fun." (C. Bell)

924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment
Back to top
View user's profile Send private message Send e-mail MSN Messenger
pocketscience  



Joined: 23 Apr 2006
Posts: 1648
Location: Sydney, Australia... mate!

PostPosted: Wed Oct 22, 2008 7:14 pm    Post subject: Reply with quote

Dan, as always - you rock!

Martijnus are you copying everything I'm doing...!


Cheers,
Gavin.
_________________
Whoever said you can't buy happiness forgot about Porsche!
81 924 N/A, GTS lights, Saratoga, interior, headers, Integral cam, EFI (sold)
94 993
Back to top
View user's profile Send private message Visit poster's website
Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11328
Location: PacNW

PostPosted: Thu Oct 23, 2008 4:05 am    Post subject: Reply with quote

IMO, there is NOTHING to be gained from swapping one set of steel trailing arms for another. . .it will just make the job take longer and disturb the rear alignment.

Also: your "steel to steel" pics show an Al trailing arms, and thus do not show the caliper carrier, and; somewhere in the 944 PET is a pic and part number for the rear sway bar mount that welds to the torsion carrier. . .nice for cars without rear sways.
_________________
Toofah King Bad
  • Shaggy (1980 931) - Got Boost?
  • Red (1987 924S) - Pro44/Spec944
  • Weiße Scheiße (1987 924S) - In Progress
Back to top
View user's profile Send private message Visit poster's website
ideola  



Joined: 01 Oct 2004
Posts: 15426
Location: Woodstock IL

PostPosted: Thu Oct 23, 2008 4:18 am    Post subject: Reply with quote

Rasta Monsta wrote:
IMO, there is NOTHING to be gained from swapping one set of steel trailing arms for another. . .it will just make the job take longer and disturb the rear alignment.

What is to be gained is ease of swap. If you have a four lug, chances are you have a snail shell with the funky torsion carrier. The entire supension drops right out of the donor car, and you can simply drop the old one out and bolt in the new one. IMO, this is the easiest way to do the swap instead of trying to dismantle everything in the rear. WAY easier. Especially because the bolts and nuts on the steel setups are almost ALWAYS rusty, and you'll end up breaking at least one or two of them. So, IMO, LOTS to be gained in terms of ease.

Rasta Monsta wrote:
Also: your "steel to steel" pics show an Al trailing arms, and thus do not show the caliper carrier, and; somewhere in the 944 PET is a pic and part number for the rear sway bar mount that welds to the torsion carrier. . .nice for cars without rear sways.

Notice that I didn't quote out PET part numbers, and that I wiped out the callouts. And actually, if you look in PET, all of the drawings for the trailing arms are identical from 924S to 944 to 951. For some reason, they don't illustrate the difference between the steel and alu arms. The illustrations I put up above were not meant to document every niggling little detail, but simply to provide a quick visual reference as to the parts required. As for the caliper carriers, they too are not called out separately in PET, at least in the versions that I snagged from Pelican when I threw this together. In fact, it's almost pointless to call the carriers out separately, because they are in essence an integral piece with the rear calipers, they basically come all together as a package when you take off the rear discs.
_________________
15 981 GTS | 04 955 Turbo | 88 924S SE | 82 931 (x2) | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod (x2) | 78 Poli-Form | 78 Limited Edition | 77 Martini
Back to top
View user's profile Send private message
Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11328
Location: PacNW

PostPosted: Thu Oct 23, 2008 4:30 am    Post subject: Reply with quote

Well, we'll have to disagree on this one (*shock*). . .

Once the drum is off, four bolts hold on the drum backing plate. Remove these, swap drum backing plate for caliper carrier, and you're mostly done in a very short time.

Oh, and the 85 924 PET shows the caliper carrier on 603-10 as #23, and the drum backing plate on another page.
_________________
Toofah King Bad
  • Shaggy (1980 931) - Got Boost?
  • Red (1987 924S) - Pro44/Spec944
  • Weiße Scheiße (1987 924S) - In Progress


Last edited by Rasta Monsta on Thu Oct 23, 2008 4:36 am; edited 1 time in total
Back to top
View user's profile Send private message Visit poster's website
ideola  



Joined: 01 Oct 2004
Posts: 15426
Location: Woodstock IL

PostPosted: Thu Oct 23, 2008 4:33 am    Post subject: Reply with quote

Yeah, except that many of the four bolts don't have the adjustable spring plates or sway bars, and most of the steel based 5-lugs do.
_________________
15 981 GTS | 04 955 Turbo | 88 924S SE | 82 931 (x2) | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod (x2) | 78 Poli-Form | 78 Limited Edition | 77 Martini
Back to top
View user's profile Send private message
924guy  



Joined: 29 Dec 2003
Posts: 2091
Location: Port St. Lucie, FL

PostPosted: Tue Nov 04, 2008 12:23 am    Post subject: Reply with quote

some pictures: 4 lug rear hub removal.

optional, but the drum needs to be pulled off if you want to disconnect the e-brake cable at the drum, and that wont happen easily unless you have one of these tools, as the castellated nut is torqued to 250 lbs. Its best to do this with the wheel still on, and the car on the ground to loosen it. I didnt, but with prodigious smashing of the tool with a hammer, and a tight grip on the drum, I was able to free the bolt as you see it below:



remove securing nut from behind, and unhook cable end, pull through (it will take some fidgeting with.)


disconnect brake line. I chose to disconnect the line junction above the torsion bar carrier because its in line with the end of the swing arm and i knew that line was being replaced, so no loss if i stipped the nut or cracked the line (which is exactly what happened!)


remove stub axle bolts, make sure you have the right tool, most are triple square. I used my breaker bar to stop the hub from spinning because I removed the ebrake cable first. if your ebrake works, you can apply it and lock the hub that way.



Next I went ahead and loosened all the securing bolts, but you want to mark the location frist, scribe around the outside of the spring plate, or make a shadow using spray paint, so you know where to put the new parts.



e-brake cable notes: the ebrake cable is two pieces, the main cable starts at the pull handle, travels through the body, and across to the right rear hub. the left rear hub has a shorter cable which connects to the main cable center car above the torsion bar carrier via a bracket and 10mm bolt/nut pin configuration. there are also brackets on the carrier it sits in, secured by c clips. Its a pain in the neck, and I will do a separate write up on it at a later time, but it must be removed and updated to work with the five lug hubs.

Once all of that is disconnected, I used a floor jack to maneuver the hub in order to unbolt the rear shocks, and remove the remainder of the assembly securing bolts. Then dropped the unit dowm, Its heavy, dont let if fall and crush your toes....

notes: If you dont have air tools, 1/2 drive inch sockets(10, 13, 15, 17, 19mm,) breaker bar are recommended. you need the torque of a long bar. I sprayed all bolts and tapped in pj blaster for several days before hand, given the rusty nature of the parts. I got my triple square socket set from SIR tools, I don't remember where i found the castellated nut removal tool, but its a vw tool and can still be found for under $30. a hammer, flare nut wrenches, and metric open end wrenches will also be necessary. The back nuts on the spring plates are a challenge to get too, and there's no room for a closed end wrench.


Installation of the five lug hub is as they say, reverse of removal.

some notes:
In my case, i had the early rear sway bar without end links, two mounting holes on each side, bit of a pita to get it to line up right, but once i got the top bolts through, i was able to use my floor jack to preload it a bit and it lined right up.

the hubs are heavy, though no heavier than the drum assemblies, if not a bit lighter, but it does take some doing to get them in place and lined up correctly. I had a bit of help , just needed someone to pop a bolt in the spring plate to hold it up, then was able to maneuver the rest of the assembly in place with a bit of shoving.


be prepared for brake line failure,especially when cracking connections that have rusted into solid lumps after 30+ years. My under car brake lines were shot and I had to replace them. With the hub out, it make things allot easier to get them around the torsion carrier and ensure the correct bends. I also killed a flange wrench in the process, get good ones, my cheapos bought it early on.




One of the brake lines on on of my 5 lug hubs was crushed (under the bleeder) someone had obviously pounded it with a hammer at some point. It much easier to replace them with the hub out of the car. inspect them first, repack the bearings, ect. or spend twice as much time fixing them later...

All that's left for me is to go back and torque all bolts to spec, complete the e-brake re-assembly, and double check that the ride height is correct. And of course some cleaning and repainting, which i should of done while the parts were out, but I ran out of paint and wanted to get the mechanicals done so I could get the car off the jack stands before the neighbors start complaining..
_________________
Eric
78 924
82 931 SE "smokey"
99' VehiCross
Y2K Honda Insight
http://www.cardomain.com/id/924Guy
Performance by Pasha
Back to top
View user's profile Send private message Visit poster's website
ideola  



Joined: 01 Oct 2004
Posts: 15426
Location: Woodstock IL

PostPosted: Wed Nov 26, 2008 11:20 pm    Post subject: Reply with quote

Here is an interesting webpage. It's in Dutch, but if you use translate.google.com and past the URL into the website field, you can get a functional if not perfect translation.

http://porsche.elevate.nl/technical/924/brakes.html
_________________
15 981 GTS | 04 955 Turbo | 88 924S SE | 82 931 (x2) | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod (x2) | 78 Poli-Form | 78 Limited Edition | 77 Martini
Back to top
View user's profile Send private message
pocketscience  



Joined: 23 Apr 2006
Posts: 1648
Location: Sydney, Australia... mate!

PostPosted: Thu Nov 27, 2008 8:49 am    Post subject: Reply with quote

I replaced my flex brake hoses with SS jobbies a while back. Will these be re-usable with 5-lug setup?. I'm assuming if I don't touch them then the rest of the hardlines can stay as they are?


Cheers,
_________________
Whoever said you can't buy happiness forgot about Porsche!
81 924 N/A, GTS lights, Saratoga, interior, headers, Integral cam, EFI (sold)
94 993
Back to top
View user's profile Send private message Visit poster's website
Martijnus  



Joined: 29 Dec 2006
Posts: 2020
Location: Netherlands

PostPosted: Thu Nov 27, 2008 9:36 am    Post subject: Reply with quote

ideola wrote:
Here is an interesting webpage. It's in Dutch, but if you use translate.google.com and past the URL into the website field, you can get a functional if not perfect translation.

http://porsche.elevate.nl/technical/924/brakes.html


if I wasn't lazy as hell I'd translate it for you all... but it's too much at the moment
_________________
"Rule: Turbo's make torque, and torque makes fun." (C. Bell)

924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment
Back to top
View user's profile Send private message Send e-mail MSN Messenger
Martijnus  



Joined: 29 Dec 2006
Posts: 2020
Location: Netherlands

PostPosted: Mon Dec 01, 2008 6:10 am    Post subject: Reply with quote

got myself some 5lug conversion stuff from baldwin (thanks again!) so we'll see how good this howto is in practice
_________________
"Rule: Turbo's make torque, and torque makes fun." (C. Bell)

924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment
Back to top
View user's profile Send private message Send e-mail MSN Messenger
ideola  



Joined: 01 Oct 2004
Posts: 15426
Location: Woodstock IL

PostPosted: Fri Dec 05, 2008 12:00 am    Post subject: Reply with quote

I have just posted a major update to the SUSPENSION, BRAKES, WHEELS & TIRES section of the Performance Upgrades thread. Rather than repeating that information here, and needing to maintain it in two places, please use the cross reference to gather more information about the various permutations and considerations for 5-lug conversions.
_________________
15 981 GTS | 04 955 Turbo | 88 924S SE | 82 931 (x2) | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod (x2) | 78 Poli-Form | 78 Limited Edition | 77 Martini
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    924Board.org Forum Index -> How-To All times are GMT + 10 Hours
Goto page 1, 2, 3  Next
Page 1 of 3

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group