og900 4spd gearbox ???'s

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stig-swoosh
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og900 4spd gearbox ???'s

Postby stig-swoosh » Fri Jul 27, 2007 3:56 pm

There's a '79 900T down here in the junkyard with a G44502 gearbox & since it's only 50 bucks I thought I'd get it to install down the road...I stuck a magnet down into the filler hole & no chunkies pulled out,the car has massive rear end damage so I guess that's why it's there...it has 230,000 miles...
the PROBLEM is when they moved the car with a forklift (it's a u-pull-it yard) they badly damaged the gearbox drain plug,it's still sealed,but half the shoulder got ripped off,I could probably drill the plug out,but is it possible (or wise) to try & weld the shoulders of the boss on cast aluminium & rethread it? Also I was curious if the untapped boss right behind the g.b. drain closer to the r. diff. cover could be tapped & used for the drain?

Since it's got the 5 primary,I'd like to change to 7(which I've found online),but I've heard of people using 5spd primaries...anybody got experience with this?

It's a 871 239 cast #,so I don't think it's the "strongest" of the "kokill" boxes which have the diagonal ribs...as Jörgen says here:
http://www.xn--kpslp-jra6j.nu/vaxellador.html
...which roughly translated is something like this...
1)The cast number is supposed to be 870423 or 871239,of these numbers there are many casts of different strength.You can say that all these housings are very strong,but if you want the strongest it is the one with 3 diagonal ribs on the forward right corner in the oilpan.
2)How to see if it's a strong cast is to look at the ribs on the right side of the trans-housing,they are horizontal,this is the easiest way to be sure.
3)The primary housing should have 3 strengthening ribs under the slave cyl. that is 1cm wide and with a distance of 3cm between each.If it's 3cm wide with 1cm between each,it's wrong.

also,a good thread is here:
http://www.900aero.com/phpBB2/viewtopic.php?t=1114

Any thoughts/opinions on running the 4spd boxes on uprated og 900's?
...my future project og900 will not be crazy-ass gnarly,but mildly tuned...I've liked the gearing on the coupla 99's I've driven,so if this setup would be similar,I think I'd diggit.

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Luke
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Postby Luke » Sun Jul 29, 2007 7:23 pm

We repaired a similar cracked drain we suffered. Basically we spun a whole new neck and welded in on... while still in the car! Still using that same tranny now.
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More info in this post: http://saabrally.com/WordPress/?p=6

Hans
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Re: og900 4spd gearbox ???'s

Postby Hans » Sun Jul 29, 2007 10:20 pm

stig-swoosh wrote:Any thoughts/opinions on running the 4spd boxes on uprated og 900's?
...my future project og900 will not be crazy-ass gnarly,but mildly tuned...I've liked the gearing on the coupla 99's I've driven,so if this setup would be similar,I think I'd diggit.

I have a 4-speed that came with #4 primaries in my '86. When I had the Quaife installed recently, I had taller primaries put in -- they are too tall (nearly 70mph at the top of 2nd, stock redline). So I'm going to try something in between when I remove them next weekend. This car is a toy, a work-in-progress project, and I don't drive it much except to/from autocrosses. The gearing with the #4s is not great for the highway, but it's pretty damn fun everywhere else. I'll try and post some 4-speed gearing specs later...

As for #7s, go to the c900 board at saablink.net and search -- I recall that someone has done this there. However, I also seem to recall that one of the 900 primaries is incompatible with the 99 splines; you'll want to check.

Some details on putting a 4-speed into a c900:

1. ASSuming you've got a 16V car, you'll need to figure out how to add oil, as the 4-speed dipstick tube is quite narrow. I put a "massaged" plastic Subaru filler on the valve cover. Another option is to weld a cap onto the valve cover (see Summit or Jegs or from a junkyard car for aluminum caps). You could also weld a 5-speed dipstick/filler hole into the 'box, but that seems like a lot of work.

If you have an 8V car, and it's got a distick/filler, I believe there were some years with the oil filler in the valve cover.

2. You'll need the downpipe hanger from the 4-speed Turbo donor -- a 5-speed hanger will NOT work. Use Red Loctite on the bolts.

3. If the c900 is a Turbo, you'll need to notch the turbo bracket to clear a rib on the primary case -- takes two minutes.

4. You'll need a 4-speed shifter. That said, you may be able to get away with the existing 5-speed shifter if you take the plastic shift "gate" from the 4-speed and bolt it to the 5-speed shifter (I have a 4-speed shifter so haven't done this). If you use the 5-speed shifter without altering it, you'll have to learn how to find 3rd gear, as the gate allows the shifter to travel too far over.

5. There's no centering on these boxes. If your car has an externally-centered shifter, then it's probably worth trying to make it work with a 4-speed gate on it.

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Postby stig-swoosh » Mon Jul 30, 2007 1:50 am

:) Cool,thanx for the info Luke...I really like the steel helicoil idea! Seeing y'all fixit up like that made me alot more confident about nursin' this box back to the world of torque...

Hans...damn,I bet it is more than pretty damn fun with the #4s...forkin' screamin' hellsbells fun I bet...what were the primaries you put in that seemed too tall?...thanx for sugging saablink,I stayed awhile & alotta good infos to be found...

2).the dp hanger is the style which bolts to the rear diff. cover,I've heard also there is a different style but I forget where it mounts?

4).I was hoping to keep my 5spd shifter,it's a Jörgen shifter & use the 4spd gate & if I don't like the non-centering feel,add an 86 style centering mech.,is that do-able?

I'd be super interested in the 4-spd gearing specs...

I found some pix online of the badass "kokill 870423" (which was installed inna gnarly-gnarl hi-po og900)that burst its seams from too much horsehoofin' tween its girdle...sad :cry: (but also strangely exciting) :twisted:



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Hans
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Postby Hans » Mon Jul 30, 2007 2:32 am

stig-swoosh wrote:what were the primaries you put in that seemed too tall?...
Not sure, exactly -- Rob @ Scanwest cooked them up from his stash and may have mixed/matched primaries. From a stop, on a slight hill, 1st felt like 2nd.
stig-swoosh wrote:2).the dp hanger is the style which bolts to the rear diff. cover,I've heard also there is a different style but I forget where it mounts?
The hanger I'm talking about mounts at the tripod bearing flange. I was told that the style that mounts to the diff cover had a way of falling off due to vibration, liberating the gear oil from its confines at the same time. If you use it, go with the red Loctite.

stig-swoosh wrote:4).I was hoping to keep my 5spd shifter,it's a Jörgen shifter & use the 4spd gate & if I don't like the non-centering feel,add an 86 style centering mech.,is that do-able?
Try the 4-speed shift gate and see if it works. The only concern I'd have is, IIRC, the 4-speed shifter's pin is smaller (narrower) than the 5 speed. So if that's a problem with the 4-speed gate, and ASSuming the 4-speed pin can be fitted to your Jorgen 5-speed shifter, you'd be OK.

stig-swoosh wrote:I'd be super interested in the 4-spd gearing specs...

http://www.bluesedan.com/gearing/4_speed_gearing.bmp
http://www.bluesedan.com/gearing/early900gearboxes.bmp
Potentially useful c900 gearing info:
http://www.bluesedan.com/gearing/900_saabgear1.jpg
http://www.bluesedan.com/gearing/900_saabgear2.jpg
Sorry, nothing for 82-85 boxes...

(Thanks to DougM on Saabnet for the scans. Can't seem to find his on saabpics.org - can't ever seem to find stuff there...)


stig-swoosh wrote:I found some pix online of the badass "kokill 870423" (which was installed inna gnarly-gnarl hi-po og900)that burst its seams from too much horsehoofin' tween its girdle...sad :cry: (but also strangely exciting) :twisted:
Ouch... :shock:

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Postby Geoff » Mon Jul 30, 2007 9:48 am

One thing to note about these gear ratios is that the ratios in the stock 4spd boxes are pretty similar to those in the stock 5spd boxes in 1st through 4th gear. Many of the 5spds are geared similarly to 4spds with an extra gear on top (5th). The major exception is that in some of the 5spd boxes, 1st gear and sometimes 2nd, are significantly shorter (the higher number in the overall ratio means a shorter gearing). This means that some of the 4spd boxes have gearing that is quicker between gears 1st to 2nd to 3rd. I've always felt that some of the 5spds were too short ratioed in 1st and 2nd. I've always found that driving a 4spd car with someone else following/leading in a 5spd car if we're both in 4th gear we're just around the same RPM (which makes sense when you look at the gear ratios).

I know Seth put 5spd primaries into a 4spd and said that the car was a dog. Of course if you had a ton of HP it might not be bad (see what Peugeot or Citroen did a few years back with their WRC cars when they switched from a 6spd to a 4spd to spend less time shifting). If you're going to put different ratios in a 4spd I'd start with turbo primaries as they make things a bit longer but not super long. The longer primaries will apply less torque through the components in the box so will reduce some stresses.

Thanks for the photos and translation from Jorgen's site. I looked at one of my boxes this weekend and found that it has the 1cm wide ribs with 3cm spaces under the slave cylinder, horizontal ribs on the right side of the box, but it doesn't have the diagonal ribs in the corner of the oil pan. 'll have to inventory my others sometime. My opinion on the gearboxes (and it may be wrong) is that there are some 4spd cases that are the strongest cases out there, the 5spd cases are probably all weaker. However the 5spd internal components are, for the most part, stronger than most of the 4spd internal components (with exceptions). You can mix and match parts along with make some others to make the strongest box. To do this you have to use the strong 4spd case and this is why people say that the 4spds are the strongest. A stock 5spd would outlast a stock 4spd on a high power car. But a stock 5spd under a stock 160hp C900T engine won't necessarily outlast a stock 4spd under a stock 110hp B engine.

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Postby sonett » Mon Jul 30, 2007 1:47 pm

This is what you should be looking for...
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The best standard box to use for rallying and to get the shortest gears is a 5 speed with type 4 primaries. Of course a 4speed with competition gears would be ideal, but for those on a budget this is a good compromise.

Standard 5 speed box;

at 1000rpm
1st 4.88mph
2nd 8.64mph
3rd 12.84mph
4th 17.82mph
5th 22.08mph

5 speed box with type 4 primaries'

1st 4.2mph
2nd 7.44mph
3rd 11.10mph
4th 15.48mph
5th 19.14mph

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Postby stig-swoosh » Mon Jul 30, 2007 3:08 pm

Hans)))...'preciate you postin' the box specs...& thanx for the dp hanger description,I think the one on this car was the early style that the bolts vibrated loose,as you pointed out,red Loctite is essential...I guess the hanger on the tripod bearing flange was the factory solution after having probs in the field?

Geoff)))...thanx for the good infos...I think once I get this box home & broke open to see really how it looks,I may just end up staying w/ the #5 primaries that's innit...I can't take credit for translating Jorgen's page,I found that here:
http://www.saabcentral.com/forums/showthread.php?t=37037&highlight=4+speed
I read Swedish verrrrrry slowly & get hung up on alot of words,and my translations are usually a bit iffy,especially with colloquial & informal words maybe not so easy with a "ordbok"...this online translator works fairly well :
http://www.translation-guide.com/free_online_translators.php?from=Swedish&to=English
...but it ain't good for doing whole webpages,comes out like dada avant-garde-poetry or something...it works best with only a few words at a time & crosschecking alternate definitions back from SWE to Eng to be sure it seems right...

Sonett)))... :!: yup,that's the BEEFYHEARTED box!...do you happen to know if any early900's got the 870423 box,I have a feeling that it was mostly 78 maybe?...I was hoping the 79 900 in the scrapyard woulda beena late 78 build date,but it was from june 79...
Last edited by stig-swoosh on Tue Aug 07, 2007 12:49 pm, edited 1 time in total.

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Postby Geoff » Mon Jul 30, 2007 3:21 pm

Here's a graph of the speeds I get in my 5spd gearbox (45612 w/#4 primaries) vs the stock gearbox and the Speedparts gear set with their special 29/32 primaries. All speeds assume using the 'special 205/55/16 rally tires' that Speedparts did their calculations at.
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1st gear looks very close but in fact it is super short. I sometimes start rallyXes in 2nd (and the car has pretty much no power). Note how my gearbox is pretty much the same 2nd through 5th as the Speedparts box is 1st through 4th. Of course mine isn't as strong :lol:

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Luke
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Postby Luke » Mon Jul 30, 2007 4:15 pm

That looks like a very early 4 spd to me, its got the two bosses for early style motor mount.

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Postby sonett » Mon Jul 30, 2007 4:44 pm

stig-swoosh wrote:Sonett)))... :!: yup,that's the BEEFYHEARTED box!...do you happen to know if any early900's got the 870423 box,I have a feeling that it was mostly 78 maybe?...I was hoping the 79 900 in the scrapyard woulda beena late 78 build date,but it was from june 79...


The main part of that 870423 was removed from an early 1976 3 door single carb model, i have also removed one from a '77 car. The box in question had a gear type primary drive, the primary housing in the picture is from a 1980 99 turbo box.
I don't think you would find this box on a 900, from what i have seen they appear to turn up on 99; from 75 ish up to maybe '78.

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Postby stig-swoosh » Tue Aug 07, 2007 12:18 pm

I was surprised when I popped the block off to see the 3 diagonal ridges...I was thinking the 871 239 boxes were all of the "medium" strength...so I was happy to find the "strong casting"...
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:shock: ...but,what the hell caused this or how the devil it happened I have no idea,maybe not forklift damage afterall as I initially thought...some over-zealous jiffylube or hamfisted previous owner? :roll: ...anyway,it should be a fairly straightforward repair...
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:evil: ...extra gnarly halloween shot... :evil:
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Postby Rallyho » Tue Aug 07, 2007 1:29 pm

This is most likely way off topic, but here goes:

I've got a 4spd that I want to put into an 85 900 body. Will the 5spd front tranny cover (and motor mount, mount) fit on the 4spd box?

Thanks.
Rallyho

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Postby Geoff » Tue Aug 07, 2007 2:04 pm

yup!

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Postby Crazyswede » Tue Aug 07, 2007 2:08 pm

putting the 5 speed cover on the 4 speed is no problem. Its going the other way that you need the 80 and up 4 speed cover...ie putting the 5 speed in the 99 with the 99 motor mount needs the 80+ cover.
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