1978 450SLC Super beater/lemons race car - Page 8 - PeachParts Mercedes-Benz Forum

rwd4evr · #**106** 03-22-2017, 05:09 PM

Well I got a little work on the front done. I didn't really have time for fabrication so I decided to pull the bumper and garbage fender off. The amount of undercoating up in there is just absolutely ridiculous. I would say close to a half inch in a few places and then the headlight bucket has 3/4 of an inch about 4 inches around gluing it to the inner fender structure, fonzi and I were cutting and prying and cussing. It's gonna be fun realigning the flange it bolts to. Luckily the donor 560sl is a second gen car with the plastic inner fender and no stupid undercoating.

rwd4evr · #**107** 05-31-2017, 06:32 AM

Damn, two months and nothin done really. Busy with other things plus a bunch of fun stuff comes around this time of year and work.

I got back on the passenger side rear frame rail area today. I really want to drive it and NEED to get the rear back under it so i can get it off the lift. I have WAAAY too many cars now and even outside of the shop room is about full, the lift will really help with some tear downs and body scrapping. I have to at least do this inner part before the subframe goes back in. The other side wasn't nearly as bad internally somehow. So the more i stared at it to figure out how to do it, the more i saw how much structure was missing. being that this car is going to get hammered on i Decided to basically recreate the inner forward portion of the rail the way it was originally, extending the rocker straight back and then I will bring the curved rear portion forward to overlap that part to tie them together like factory. I have the first part fabbed and fitted but not welded in yet. I had to reinforce the jack hole structure too. I forgot to get pics of it while it's opened up.

On a side note I just picked up a '85 500 sl thats really nice but missing a couple things. I'm hoping to pull the tri-y manifolds off and build a jig to recreate them. it need the down pipes so we're trying to get them but may have to make them as well. Hopefully i don't need to take them off fonzi's 450slc 5.0 to recreate them.

I missed one auto cross i was hoping to get to and the second was rained out. I was going to run a 280se 4speed. I actually found a bunch of auto cross events not too far from home and even a couple different rally cross' too. Basically an off road auto cross. that should be fun but it makes me rethink the spring cutting idea. Adjustable spring perches for ride height changes would be way better. Welded diff may have to happen until i get an lsd of some sort. I want to keep my options open for different racing.

97 SL320 · #**108** 05-31-2017, 06:26 PM

Quote:

Originally Posted by rwd4evr

Basically an off road auto cross. that should be fun but it makes me rethink the spring cutting idea. Adjustable spring perches for ride height changes would be way better. Welded diff may have to happen until i get an lsd of some sort. I want to keep my options open for different racing.

For adjustable spring ideas have a look at this post but ignore the original poster.

http://www.peachparts.com/shopforum/performance-paddock/342744-w123-racing-setup-serious-questions-within.html

A welded diff is hard on axles and CV joints since there is zero give in corners.

rwd4evr · #**109** 06-01-2017, 05:47 AM

yes i was looking for some thing like that. The only issue is that the springs are always preloaded even when the car is jacked up. you would have to drop the shock to release tension to spin it up or down i think. it doesnt have splines like a coilover perch to use a wrench on. if the shock wasn't in the spring a threaded jack plate you could adjust with a ratchet would be great. this type would be so hard to get a hand or anything on to turn it up in the upper spring pocket.

fonzi · #**110** 06-01-2017, 08:14 AM

If just looking for a one-time adjustment, wouldn't it be possible to fit a coil-over in place of the shock?

(Ignore the fact that the bottom is not the correct connection type, but I assume it wouldn't be impossible to fabricate an adapter or find the correct base type.)

I guess the trick is finding a coil over small enough to insert into the control arm without removing or compressing the entire spring.

I personally am selfishly looking for a little extra weight support on my custom convertible SLC 5.0, which is why I'm chiming in and researching this myself.

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fonzi · #**111** 06-01-2017, 08:25 AM

https://statusgruppe.com/products/bmw-e46-m3-srs-coilover-kit

These guys appear to have special wrenches that might fit through the main springs to adjust the shock coil springs. I went to their site after doing a google image search seeing what looked almost like a base that would mount to the bottom of a MB SLC control arm.

The more I think about it, MB steel control arms aren't exactly expensive, and whole rear ends from SLCs can be had relatively easily. So if you need to cut the hole larger in the control arm, I bet you could find a way to make the bottom mounting area strong enough with minor fabrication and welding.

I wonder if you could cut out a small section of the control arm where the spring/shocks sit and mail it to a coil-over maker for them to provide a suggestion.

...
And a whole different option, KYB Gas Adjust. I was expecting to find a result of a google search where the shocks could be controlled via external air, but this came up, and it seems really really simple.
https://youtu.be/J_V4JAIOF2c

97 SL320 · #**112** 06-01-2017, 04:24 PM

Quote:

Originally Posted by rwd4evr

yes i was looking for some thing like that. The only issue is that the springs are always preloaded even when the car is jacked up. you would have to drop the shock to release tension to spin it up or down i think. it doesnt have splines like a coilover perch to use a wrench on. if the shock wasn't in the spring a threaded jack plate you could adjust with a ratchet would be great. this type would be so hard to get a hand or anything on to turn it up in the upper spring pocket.

If you used a circle track "hidden" adjustable spacer, you would need to take the spring out to make adjustments as they don't have notches like a coil over.

If you had a jack screw type they can be adjusted with full weight however as you said, the shock gets in the way so this setup won't work.

rwd4evr · #**113** 06-02-2017, 12:10 AM

Coilovers would solve pretty much all the problems except the $1000 or so to buy them. I looked at this idea years ago for my s13 240sx. Its a cantilever setup that uses sport bike adjustable rear shocks with a pushrod in place of the spring and shock and a 90 degree or so turn with a rocker arm lever. It may be possible on a slc, i have to look at it. If so its pretty much unlimited in height and the lever ratio can change shock travel and spring stiffness plus ride height. Stock adjustable hayabusa gsxr1300 rear shocks are like $60 and can be resprung and revalved however needed. so a lever ratio change could theoretically have it low with stiff for on road and high with softer rate and long travel for off road. Damn now i want to go look at the car.

fonzi · #**114** 06-02-2017, 08:16 AM

I never would have been able to envision what you were talking about without those pictures. It seems like it would be a lot of fabrication, but I can't see why it would not work. Doing all the calculations or getting the geometry to work the way you want inexpensively seems complicated. (And certainly a no-go for my SLC convertible. I should just replace my shocks and maybe use some spring pads or find stiffer springs, wondering if W126 springs would be stiffer and fit. I assume they'd fit since they use the same control arms as SLCs.)

So back to your "shocks through the tower" concept...
- When you bolt the top of a shock to the body of the car, it is fixed. It seems this setup requires additional travel through the top of the shock tower with taller shocks.
- In order to have the shock travel through the top, do you drill out the body somehow allowing the rod to all fit through the body? And not use the washer I guess.

Interesting.

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97 SL320 · #**115** 06-02-2017, 10:15 AM

Pretty much the only reason to have a pushrod / pull rod suspension is to take the shock / spring out of the air stream. ( Indy car / F1 of even an entry level Formula Ford ) Past that, it is too much work and $.

For alternate coil overs, look at AFCO in the oval track section , I'm pretty sure you can still get old school shocks that will take coil over adjuster sleeves.

rwd4evr · #**116** 06-04-2017, 03:06 AM

Well.....getting the shocks and springs out of the air is one reason for using a bellcrank/pushrod type suspension but there are lots more reasons. I'm pretty sure that class 8 trophy trucks aren't using them for that. They are used to slow down piston speed and reduce heat in long travel systems, plus you can use a shorter shock for longer travel. Just adjusting the length or even changing the pushrod entirely is instant height adjustment, combined with bellcrank ratio change for spring stiffness. Also used for packaging issues like where springs and shocks just can't live where you would like them to be. People will say reducing unsprung weight too but with the bellcrank and pushrod weight add it would be negligible i think. Big ass steel springs are way heavier than the small bike springs though.

I found some kits that can convert some conventional shocks to threaded sleeve coilover types but they require some machining of the shock body and they're $350. The other issue with that is that i'm not sure the shock mounts are capable of supporting full weight of the car. Also you still would have a non adjustable shock and getting at them to adjust the height would be very difficult on a c107. the motorcycle shocks are fully adjustable for rebound and compression and are pretty high quality and can be bought for as little as $30. If i decide to go ahead with this idea in the rear i will design it so i can add another shock if they are running hot from over exertion. You have to remember that the motion ratio on the bike is far higher because of the length of the swingarm, so it sees much more than the actual wheel weight. The spring rate on the bike shock is very high considering how light they are.

I don't see the fabrication being too difficult and money is far lower than any other option to have such adjustability built in. Cash output would be limited to some nice rod ends, the shocks and steel for the structure and since i grab any usefull steel tubing i see out on the side of the road, like exercise equipment especially, I already have most of that. this guy did has a nice job and it happens to be a mercedes. I would use a similar design i think. the original pics of "the track cat" design have a few flaws and would flex like mad.
https://www.youtube.com/watch?v=PdXt4swCux4

As far as the front end, the AFCO threaded weight jacks/spring perch will work very well i think for height adjustment since the shocks arent in the coil spring. Then i can use stock springs cut to reduce ride height (1.5 to 2" would be maximum without geometry issues) and increase spring rate, then using the threaded spring perch could adjust ride height up 4-5 inches for off road. I put some pics up for anyone who isn't familiar with the weight jacks. One actually has a ball so it can swivel with the spring as it goes through its motions. If you have ever watched a nascar race and saw the crew turning a wrench in the base of the rear window they are turning a weight jack to adjust that corners load. The plate is welded into the top of the spring pocket(in the subframe) and the part with the threaded rod(spring hat) sits on top of the spring. turning the threaded rod in screws the spring hat downward increasing ride height.

rwd4evr · #**117** 06-04-2017, 03:21 AM

Quote:

Originally Posted by fonzi

I never would have been able to envision what you were talking about without those pictures. It seems like it would be a lot of fabrication, but I can't see why it would not work. Doing all the calculations or getting the geometry to work the way you want inexpensively seems complicated. (And certainly a no-go for my SLC convertible. I should just replace my shocks and maybe use some spring pads or find stiffer springs, wondering if W126 springs would be stiffer and fit. I assume they'd fit since they use the same control arms as SLCs.)

So back to your "shocks through the tower" concept...
- When you bolt the top of a shock to the body of the car, it is fixed. It seems this setup requires additional travel through the top of the shock tower with taller shocks.
- In order to have the shock travel through the top, do you drill out the body somehow allowing the rod to all fit through the body? And not use the washer I guess.

Interesting.

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Yes the push rod would be coming through the original top shock mount hole, then acting on the bellcrank mounted above it, turning the force 90 degrees pushing on the shock and spring mounted pointing at each other and the centerline of the car. no rear seat would be possible so it wouldn't help with your issues. w126 springs should fit but static height could be different. We'll know more after the rear of the 300se is apart.

97 SL320 · #**118** 06-04-2017, 09:33 AM

Quote:

Originally Posted by rwd4evr

Well.....getting the shocks and springs out of the air is one reason for using a bellcrank/pushrod type suspension but there are lots more reasons. I'm pretty sure that class 8 trophy trucks aren't using them for that. They are used to slow down piston speed and reduce heat in long travel systems, plus you can use a shorter shock for longer travel.

Perhaps in this application push rod makes better packaging, however heating won't be reduced since damping energy at the wheel is constant regardless of what is controlling it. For what you are wanting to accomplish, it is too much overhead for little gain.

Quote:

Originally Posted by rwd4evr

As far as the front end, the AFCO threaded weight jacks/spring perch will work very well i think for height adjustment since the shocks arent in the coil spring. Then i can use stock springs cut to reduce ride height (1.5 to 2" would be maximum without geometry issues) and increase spring rate, then using the threaded spring perch could adjust ride height up 4-5 inches for off road.

It is sounding like the rear is the only end with a shock inside the spring correct? If so, just move the shock outside the spring and use the pictured adjusters. It would also be much better to go straight to race springs as used race parts places usually have piles of them.

fonzi · #**119** 06-04-2017, 04:28 PM

Quote:

Originally Posted by 97 SL320

It is sounding like the rear is the only end with a shock inside the spring correct? If so, just move the shock outside the spring and use the pictured adjusters. It would also be much better to go straight to race springs as used race parts places usually have piles of them.

The front shock is outside the spring on the r/c107 rear axle, which also use the same rear control arms as the w114/115, w123, and w126.

Personally, I think the bell crank system would be no more difficult to implement than moving the shock.

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rwd4evr · #**120** 06-04-2017, 09:41 PM

Quote:

Originally Posted by fonzi

The front shock is outside the spring on the r/c107 rear axle, which also use the same rear control arms as the w114/115, w123, and w126.

Personally, I think the bell crank system would be no more difficult to implement than moving the shock.

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Quote:

Originally Posted by fonzi

Personally, I think the bell crank system would be no more difficult to implement than moving the shock.

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Right. There's nowhere to move the shock to without building a whole new shock Tower, and cutting a bunch out of the rear structure where the spring perch is and would still need it's strength if using the original spring placement. I did a little more research and I think a pair of shocks and springs off a 07 gsxr1000 on each side would be ideal. Now I have to measure some stuff to see if it's feasible in the given space. I honestly only looked at the car for a second since I considered this for this car.

In the front I know that two coils does a pretty good job lowering an iron block r107 and unless your buying nice eibach race springs I don't see any advantage over a mb spring cut down. I would have to see if the cut spring plus a little raise in static height with a jack screw would cause coil bind at a point that would break **** though. Still kinda thinking out loud on this stuff.