Mercedes W114 250 Coupe - help!

[Charles Morgan]

What bothers me as much is the cloud of unknowing for a RHD installation - numerous details are different, not least the steering!

Hence the necessity to get stuck in to the technical bits.

In the meantime, still plenty to do on the car but I need to decide soon as procurement of parts is going to have to be done as I want this back on the road for the summer.

 

[grober]

Picture is worth a thousand words.
1976 Mercedes 240D M117 5.5 liter | Retro Rides

Sound as if in that particular German conversion he had to incline the engine slightly to clear the steering box-- but that may be a function of the design of the exhaust manifolds and block height. However the American conversion which does away with those bulkhead to chasssis rails doesn't appear to have the same problem ----altho the shape of the gearbox bellhousing used may have some influence. [ the German one uses a 5 speed manual box and clutch??]

AND

As Bellow hinted with one off engineering projects like these there is no substitute for trying the engine+gearbox in situ and then deciding whats required in the way of engineering mods . I have a vague memory of W123 V8 conversions abandoning the Steering box+idler + linkage in favour of the more compact rack and pinion set up from much later models. For the life of me I can't remember if the rack was mounted on the bulkhead or subframe with fabricated brackets.

 

[Bellow]

Which way are the cylinder banks staggered? If the OS one is staged slightly forward there should be more clearance for the steering box.

 

[grober]

M116 Alloy Block Bore Condition - Topklasse Discussion Board

 

[Bellow]

Which way are the cylinder banks staggered? If the OS one is staged slightly forward there should be more clearance for the steering box.

Evidently, not favourably.

 

[grober]

I'm going to try to find that V8 thread with the rack and pinion steering conversion tomorrow.

 

[John Jones Jr]

As Bellow hinted with one off engineering projects like these there is no substitute for trying the engine+gearbox in situ and then deciding whats required in the way of engineering mods .

I go as far to say it's the only way. Reading up on German or U.S. conversations is no doubt worthwhile but somewhat futile with a R/h/d vehicle. Initially it's going to be a case lifting the new engine & box in and out several times to establish what modifications are required to be carried out to the current cars chassis, steering mechanism and gearbox tunnel.

So, at this juncture I wouldn't plan or purchase any parts that maybe required to fit the engine & box. It's very possible you could require an engine cross member from a R107 and retain the current steering setup for example or not as the case maybe. Time to start manhandling the new engine.

 

[Charles Morgan]

I think the study of the car that has the same cross-member and the same engine as my proposal is the most sensible. Namely the 107 SL(C). If nothing else, it's instructive on how some of the finest engineers of that generation sorted the problems out that is most satisfying.

 

[John Jones Jr]

Comparing your project to an SL/SLC is obvious but I'd suggest only to a degree. It's a fair to assume that the 107 has a different front bulkhead - lower front scuttle height with steering location to suit, different inner wings and tunnel from the factory. If so, there maybe far less relevance to your car than you may think. No matter how much you study a 107 it really won't tell you how the V8 & box are going to sit in your car. But if you get both of them sitting correctly and any steering issues overcome then you've broken the back of the project, everything else is secondary.

 

[Bellow]

The bank stagger shouldn't be too much of an issue. The width of a big end eye - half an inch.
Steering component location will be dictated by steering geometry re bump steer etc which will be set by inboard location of wishbones. It is the location of the inner ends of the track rod ends WRT the wishbone inner mounts that needs be studied most closely. Up stream, there is slightly greater flexibility re location.
It appears that the exhaust manifolds are potentially troublesome. Some lateral thinking here may pay a dividend.
Once the engine is in the bay - to hell with taking it out again! Merely shuffle and reshuffle until it all hooks up.

 

[grober]

This guy mounted the rack at the front of the cross member on a W123 V6 FORD conversion. photos here cos I couldn't get the photos up
Mercedes-Benz Forum - View Single Post - W123 V8 swap

BUT note the comments!

We put the rack in front - reason is because the oil galley on the Ford V6 is in the back, so we cut and modded the front cross member - boxed it with steel and machined new steering arms and used Steeda (i think) bump steer tie rod ends - with a straight hole / bolt combo (no reaming to fit)

Original set up used a dropped link on the MB steering, but when i put the headers in, i needed to get rid of that 50# steering box.

The new set up with the rack also has more structure because the mounting plate is a cross brace and gusted to the frame / inner wheel well= much stronger and it only takes the two OEM Ford bolts to get the rack off other than the tie rods and hoses

I needed to redesign the steering rods on the rack, and rebuilt the steering arms to get more radius out of the turn - basically move the pull closer to the pivot of the wheel to maximize the stroke of the rack. TBD

As far as bump steer, it is no more than my w203...as far as sharpness over the stock set up - no comparison - it is amazing, and aligning it is no big deal!

 

[Charles Morgan]

The steering box mounts on a /8 are a weak point on the car, a reason to avoid too large a tyre as well.

 

[grober]

This is for a W201 CONVERSION which doesn't have a subframe as such but shows what is possible with enough determination and welding gear!!-- uses a W210 rack.
LS190 - Mercedes 190e LS1 swap - LS1TECH

 

[Charles Morgan]

Just an obvious point I can't just hack the front cross member away, it has to be untouched to meet construction and use regulations.

I have decided, if I haven't got a sensible plan of action for the conversion that at least addresses which issues can be solved and which will be a matter of trial and error (with all that means for time and cost) I am going to kick the conversion into the long grass and concentrate on getting the car up and running in Megasquirt form.

To which end I managed to get the brake master cylinder out today which I shall check over and refurbish (if it's worth doing) with Tony.

 

[grober]

This is a thread that describes converting an SEC to rack and pinion. Dont worry Charles I'm with you that if you can't get the V8 to fit with the existing steering it does place a big question mark over the entire V8 conversion.
Rack & Pinion Steering - Mercedes-Benz Forum
It is useful in that it references a couple of threads on the considerable engineering involved in positioning a rack and pinion setup to avoid bump steer problems.
Bump Steer Explained - Circle Track Magazine

How to measure bumpsteer for under $10

 

[Bellow]

The left manifold was ordered to be pulled forward and downward because of the steering..

Looking at images of (what I believe to be) M117 motors the exhaust manifolds left to right are markedly different (coupling different cylinders - alternate on on side, adjacent on the other). Thus, their exits are also arranged differently side to side. With some luck, this may alleviate the problem of steering box clearance encountered on the LHD conversion.
Re oil filter, remote filter - if indeed there is a clearance problem with it.
Down pipe fabrication is more a case of pipe bending.
Assuming the components mentioned in the translation are off the shelf MB parts (eg engine mounts, propshaft couplings, etc) then any fabrication required should only be light bracketry for which it is worth buying a cheap MIG welder (with disposable gas cannister) and going DIY - MIG is very easily learned. (The sump may require surgery and if push comes to shove I could probably get that done up here for a price similar to postage in both directions). If however this is a project requiring large scale and heavy fabrication, I concur - back to the six.
I wouldn't give up on it though before exploring the possibility of a different exhaust manifold and/or slight (downward) relocation of the steering box. Tilting the engine this a way and that is a useful way of getting a smidgen of clearance where required - there are six degrees of freedom to play with...

 

[John Jones Jr]

I am going to kick the conversion into the long grass

Good move I reckon, judging by the previous posts. Anyway, the V8 conversation can be looked at again in due course with more focus (especially that you have already got the engine & box) while concentrating on making the conversation relatively easier by keeping the current or similar steering setup. It's alright talking about converting to rack & pinion but I'd only let pro with plenty of experience carry out the work required. Onwards & upwards.

 

[Charles Morgan]

Little to report, Tony is doing a new brake pipe and I met his old apprentice Duncan (over coffee and the best Eccles cake I've ever had, beautiful buttery puff pastry with plump moist raisins).

Two good rear light clusters arrived from Germany today, plating is back on track with new voltage regulator and I've finally got into the EPC for the car (my Mac hated the app to install it as it wasn't written by Apple) with an updated version of Parallels and Windows running.

Hopefully I'll get the steel wheels off soon to be powder coated. Conveniently for logistics I hit a pothole in my Alpina last evening which punctured the Michelin ps2 tyre and severely damaged the alloy. Three weeks old those tyres too. I think the coupe, with lots of rubber and long suspension travel is going to be better on local roads which are despicably bad.

 

[Charles Morgan]

Grrr, grease finally arrives, having not been in stock when they took my cash, and it is one sixth of the advertised quantity (that's the maximum parcel weight apparently). The rear lights I ordered from Germany were not quite as good as advertised but they are still ok for the price so they don't go back. Oh and the voltage regulator, bought to replace the one that blew up, blew up and didn't actually adjust the voltage output. So at £5 a load, this plating business is getting expensive!

I couldn't do this full time.

 

[grober]

A COUPLE OF PICS