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  #76  
Old 09-17-2009, 08:44 PM
GGR GGR is offline
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BTW, I now remember: There's a kind of solenoid (or whatever it is) on the right side of the trans. If it sticks out perpendicular to the trans, it's a three speed. If it sticks out at an angle, it's a four speed... But they otherwise look the same (not like the 6.3 ones, but like the 6.9 ones).

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  #77  
Old 09-17-2009, 10:48 PM
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From a not very flattering article on MB rally history here: http://www.rallye-info.com/carspecs.asp?car=203

"When Mercedes serviced by helicopter, delivering a brand new rear axle to the break down scene of a Mercedes and the new rear axle would fall and shatter into pieces as soon as it hit the ground"
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  #78  
Old 09-17-2009, 10:51 PM
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Quote:
Originally Posted by GGR View Post
Assuming your car has retained its original engine n°1283, EPC says it is equipped with the 3 speed auto trans (up to engine 1681). It also says it already has the 96.5 bore (from n°886).

So, you have the opportunity to go for a 3.5 four speed manual trans as a nearly straight fit, if ever you want so and if admitted by your rallying rules (Al who posted above has one such a gearbox for sale) and still go for the 10:1 cr with 500 SEC pistons...
Awesome! since "period" includes any modifications that could have been made in that time, surely a trans swap would be OK. What does a 3.5 4 speed go for? I wonder what that would do to my options for a diff? I know that the 560SL's all came with LSD.

Note: on Wiki they say that the SCL's has a Single Overhead Cam ;-) http://en.wikipedia.org/wiki/Mercedes-Benz_R107
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1971 Porsche 911 Targa RSR rep.
1968 BMW R60/2
1981 BMW R80GS-PD, dual plugs, 1000cc jugs, 10 gal "Gaston" tank.
1982 BMW R80GS-PD, duplicate of above.
1988 Neoplan/Mercedes 40' Bus
2002 SLK32 AMG
2013 Smart Electric

Last edited by cgoodwin; 09-17-2009 at 10:58 PM.
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  #79  
Old 09-17-2009, 11:33 PM
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I bought mine including clutchbell, throwout, fork, slave cylinder, pressure plate, clutch disc and flywheel all in good shape apart from the clutch disc, $600 on Ebay. Sjefke got one for much cheaper out of a scrapyard. I also saw higher prices asked for it. I do not know how much Alabassi is selling his, but I believe he does not have the flywheel. You should also get the shifter and the rods from him. The 4 speed gearbox is shorter than the auto trans, so you will need a longer propshaft, I gues you may find what you need id the W126 range of models.

Finding a flywheel may be tricky but you may want a ligther aluminum one. I know CTH350 was working on it, based on the measurements of the 3.5 one. This would be a straight fit for you.

For the rear diff, all depends on the use you make of the car. I hear the Carrera Panamericana has long straight stretches, you don't want your engine to overheat as those early engines are notorious to wrap the blocks when they overheat. So keeping the standard rear diff, with 300 hp may take you to some respectable speeds... Otherwise I believe MB was fitting 4.08:1 rear diffs for some races such as the Bandama...

Last edited by GGR; 09-17-2009 at 11:40 PM.
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  #80  
Old 09-17-2009, 11:47 PM
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Which cars was this trans in?
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1971 Porsche 911 Targa RSR rep.
1968 BMW R60/2
1981 BMW R80GS-PD, dual plugs, 1000cc jugs, 10 gal "Gaston" tank.
1982 BMW R80GS-PD, duplicate of above.
1988 Neoplan/Mercedes 40' Bus
2002 SLK32 AMG
2013 Smart Electric
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  #81  
Old 09-18-2009, 12:23 AM
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W108 280SE 3.5; W109 300SEL 3.5; W111 280SE Coupe 3.5; W116 350SE; r107 350SL
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  #82  
Old 09-18-2009, 03:23 AM
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Thats it,the 722 series trans . I just swapped a 280S with one into a W111 . The shifting of these old trans puts a lot of later models to shame being very fast and may be a little firm . So it wasn't only the V8's here but also the 6's. There was change over around 1972 from the fluid couple to torque convertor but you have to know the numbers when working on one to make sure which one you are working with, The coupler looks just like a torque convertor and the trannys both look the same on the outside.
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  #83  
Old 09-18-2009, 08:07 AM
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OK so a four speed auto from a 6 cylinder car fits a v8? That opens up a world of possibilities as we do have 6 cyl W123's and W116's and diesels also.
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  #84  
Old 09-18-2009, 08:27 AM
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Al, do all these cars have four speed trans? What I don't understand then is why MB didn't run the SLC 5.0 with one of these four speed auto trans then. I know the ref of the 3 speed trans for the 450 SLC 5.0 is specific to the model (maybe a question of handling the torque). Swapping around may be possible but the 4 speed trans may not hold the power and torque of the 5.0...
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  #85  
Old 09-18-2009, 08:38 AM
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Gael

The 6 cylinder cars and the Diesels had 4 speeds but the v8's of the 70's had 3 speeds. It was thought that the 4 speeds were too weak for the v8. You need to bear in mind that MB had to back the cars up with a warranty.

I did not think that that the 6 cyl 4 speed automatic transmission would bolt up to an earlier v8 though. What has my brain ticking is that there are a few W123 300D's that were sold with 5 speed manuals and I'm wondering if these would bolt up?

This would make things even more interesting in my opinion.

Certainly the later 4 speed auto that went into the 500SLC and 500SEL is a weaker transmission then the 3 speed it replaced. Both the 500SLC and the 450SLC 5.0 have the same final drive so only real benefit of running a the later four speed auto is when using 1st gear starts at the lights.

At least, the way I drive, that's not the point because if I wanted to drag race, then a period Camaro would probably run circles around my 450SLC (well in a straight line )
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  #86  
Old 09-18-2009, 09:19 AM
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Quote:
Originally Posted by alabbasi View Post
I did not think that that the 6 cyl 4 speed automatic transmission would bolt up to an earlier v8 though. What has my brain ticking is that there are a few W123 300D's that were sold with 5 speed manuals and I'm wondering if these would bolt up?
Not sure, but I think that when a friend was swapping his auto for a manual on a 123, it required a modified driveshaft.
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  #87  
Old 09-18-2009, 09:23 AM
GGR GGR is offline
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Al, as you can imagine, I have looked into the question, and there are a number of things to consider :

The 4 speed manual transmission found on the 3.5 V8 is a G76/27 A. According to the workshop manual, it is similar to the G76/27 found on the 6 cylinders, but with reinforced bearings for all shafts and a different drive shaft.

The workshop manual also refers to a G76/27 A-5 optional on the 3.5 V8s, similar to the G76/27-5 found on the 6 cylinders, but also with reinforced bearings for all shafts, a different driveshaft and slightly changed transmission ratios.

The problem is that though it is mentioned in the workshop manual, never anybody saw such a 5 speed mated to a 3.5 V8. It is belived that MB was planning to supply such an option but it never materialised.

I saw a 6 cylinder 5 speed gearbox and indeed the front casing and the input shaft are different. I don't know if it is possible to put reinforced bearings and the 3.5 input shaft and front casing of the 3.5 gearbox on a 5 speed gearbox. If yes, then we could surely and easily mate a 5 speed to an early 5.0 bloc ... Ron, what do you think?
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  #88  
Old 09-18-2009, 12:11 PM
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Interesting caliper on the Bandama pictures posted earlier. Must be alloy to reduce unsprung weight, with fins for a better cooling. And look at the part of the disc connecting with the hub: drilled everywhere I guess also to save unsprung weight... Good inspiration for us. Anyone knows where to find alloy calipers that would bolt on the original fixations? I read the 560 SL have four pistons calipers. Are they alloy?

Last edited by GGR; 09-18-2009 at 01:07 PM.
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  #89  
Old 09-18-2009, 12:24 PM
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I read that the bolt pattern on the iron and aluminum blocks was different.

I also read that the 5 spd manuals could not handle the torque of the 5.0

Mercedes did not run the 450 SLC 5.0 with the 4 speed auto because they would have had to homologate it as such, they decided to do so and dropped the cc to be less than 5 ltr and did the 4 speed trans as the 500 SLC, homologated it and went from G2 to G4 class (I believe) then found that they could still not be competitive in short distance rallys and dropped the program. Remember to race a production can you have to sell a certain number of the cars to make it a "Production car", you can't race a VW bug in a production class if you put a 911 motor in just the cars you race.... Racing is about advertising and factory sponsorship is driven by wins, not losses. Mercedes still has a reputation for durability, mostly due to the success of the 450SLC 5.0 in rally races, people today have forgotten why but everyone has heard that Mercedes are durable. Same reason they still give out mileage badges for your grill for free. Same reason lawyers are out buying BMW adventure bikes that are crap, they remember BMW winning the Dakar and BMW is still making money off that effort. The bikes I have were BMW's effort to homologate the R80GS.

Lets see if we can figure out which autos and manuals will bolt up and what cars they came in, then we need to look into the geaqr ratios of the trans and see if there is any point in doing the swap. The diesel trans are strong but the gearing is odd for a gas motor.
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1971 Porsche 911 Targa RSR rep.
1968 BMW R60/2
1981 BMW R80GS-PD, dual plugs, 1000cc jugs, 10 gal "Gaston" tank.
1982 BMW R80GS-PD, duplicate of above.
1988 Neoplan/Mercedes 40' Bus
2002 SLK32 AMG
2013 Smart Electric
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  #90  
Old 09-18-2009, 01:47 PM
GGR GGR is offline
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Assuming your car has retained its original engine, the bolt pattern of these first 1681 early alloy engines is the same as the iron blocks, apart from the two top bolts which are 9mm more towards the center of the V on the alloy bloc. This is clearly explained on the workshop manual I have about that engine. These early engines have also retained a flange between the alloy block and the clutch bell, like the iron blocks. Adapting the 3.5 four gear manual gearbox is then just a matter of redrilling/enlarging the two top holes of the clutch bell so that they align with the ones of the flange and the block. All the rest (flywheel, pilot bearing, starter motor etc.) is a straight fit as shown in the pictures I posted earlier. This is not possible on the later blocks because the bolt pattern changed and the intermediate flange disappeared.

I also read that the 5 speed would not take the torque of the 5.0, but if it's just a matter of reinforced bearings and replacement of the inputshaft, it would be interesting to give it a shot.

The gear ratios of the G76/27 A found on the 3.5 W108/109/111 Coupe are:
1st: 3.92; 2nd: 2.34; 3rd: 1.43; 4th: 1; reverse: 3.72

The gear ratios of the G76//27-5 found on the 6 cylinders on same cars are the same for all gears but the 5th which is 0.875. They were fitted with a shorter rear diff.

The gear ratios of the G76/27 found on the 350 r107 and W116 may be different.

If you want to run a four speed auto trans, apparently this is also possible as per the earlier discussion. But that wont be the same as found on the 500 SLC because the bell is integrated to the trans body and the bolt pattern is different. You will have to find a 4 speed with detachable clutchbell so that you can use yours.

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