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Narrowed rear control arms


Icehouse

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That makes sense. How wide of a tire does the Z link accommodate? I think anything wider than 225 you would have to modify the fender well anyway.

Ya at a certain point a mini tub will always be required. just having to mini tub and not having to modify suspension to run wider tires is much more inviting though  :D

Maybe, a mini tub kit in the future... hmmmmm

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We modeled it that way at first.  To make it work without limiting clearance it ends up being a "Z" arm and looks dumb and weak.  Here is a picture.   

 

 

 

 

Just make a new mount point and weld the damn thing onto the cross member where YOU want it. don't compromise on the design for sake of "bolt on". The 510 isn't a "bolt on" car. If someone can't weld they can have an exhaust shop weld it on for them...

 

Just sayin  :ninja:

 

Sucks cause this design won't work with my exhaust routing or solid mount diff setup  :blush:

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Very nice. I'm interested to see what happens with toe through the travel.

 

Suggestions: Box the upper portion of the Moustache structure. Bore a hole and insert a tubular sleeve (if needed) to provide access to the diff cover support studs.(or supply extra-long new studs.) Acceleration and brake forces are going to try to torque the mustache mount around each point where it mounts to the chassis. Boxing each side together will help  to control that stress.

 

If you want to sell these, consider squaring the arm to the angle of the mustache mount. This way, you can design around some existing O.E. rubber bushing, for those who want their car to remain somewhat civilized. The way it is currently angled, I don't think any rubber bushing would work. 

 

I've wanted to build a new structure that replaces the boomerang and mustache, but uses all the stock mounts. This is nice; cheaper and more attainable.

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To maintain stability, structural integrity, stock configuration, and bushings, you could attach the trailing arm to a shallow member mounted to both points on the X member. That would giving it up down travel and have a left right and rotating only movement connecting the arm extending to the hub.

 

Although all these designs will theoretically solve camber issues, they'll do nothing about toe trail through. Not sure if that's a good or bad thing. I also believe the shallower the mounting triangle is, the greater the squat under power will be. 

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Just make a new mount point and weld the damn thing onto the cross member where YOU want it. don't compromise on the design for sake of "bolt on". The 510 isn't a "bolt on" car. If someone can't weld they can have an exhaust shop weld it on for them...

 

Just sayin  :ninja:

 

Sucks cause this design won't work with my exhaust routing or solid mount diff setup  :blush:

Unfortunately we have to balance many more design considerations than just optimizing the suspension performance. Bolt-on reduces the amount of time we spend answering install questions so we can spend that time designing more parts  :thumbup:  Also, with bolt-on solution I can engineer all of the components with known constraints, I don't have to worry about variables like the booger welds that Bob the muffler guy puts the tabs on with. 

Bolt-on pays the bills.

 

Exhaust routing and diff. mounts are all the same. 

 

Very nice. I'm interested to see what happens with toe through the travel.

 

Suggestions: Box the upper portion of the Moustache structure. Bore a hole and insert a tubular sleeve (if needed) to provide access to the diff cover support studs.(or supply extra-long new studs.) Acceleration and brake forces are going to try to torque the mustache mount around each point where it mounts to the chassis. Boxing each side together will help  to control that stress.

 

If you want to sell these, consider squaring the arm to the angle of the mustache mount. This way, you can design around some existing O.E. rubber bushing, for those who want their car to remain somewhat civilized. The way it is currently angled, I don't think any rubber bushing would work. 

 

I've wanted to build a new structure that replaces the boomerang and mustache, but uses all the stock mounts. This is nice; cheaper and more attainable.

 

GNmaziQ.png

Predicted toe progression. Assuming the hub center is 115mm above the lower surface of the rear crossmemeber mount. (measuring ride height this way makes the measurement independent of wheel size), Aligned to 0.3 degrees toe-in per side at the 115 ride height. Also 0 camber. This keeps toe-in for over 2 inches of droop and compression. deviation from the alignment changes the rod lengths and so changes the progressions.

 

If you look the moustache-box is boxed around the suspension points and mounting points to transmit load, it is also boxed below to spread that load to the laterally. The diff mount section is single sheet to provide hand and tool access as well as to not clash with the spare tire well. This sheet is as thick as the stock mustache bar and so will handle the diff loads the same if not better due to the boxing on the ends.

 

No rubber, racecar. 

 

 

To maintain stability, structural integrity, stock configuration, and bushings, you could attach the trailing arm to a shallow member mounted to both points on the X member. That would giving it up down travel and have a left right and rotating only movement connecting the arm extending to the hub.

 

Although all these designs will theoretically solve camber issues, they'll do nothing about toe trail through. Not sure if that's a good or bad thing. I also believe the shallower the mounting triangle is, the greater the squat under power will be. 

The design allows good toe progression control. The camber control is actually more difficult. The key is that as the race rods arc they sweep in or out which changes track width slightly and adjusts toe.

 

Using the inner pivot results in ~1.5 times the upward force at the pivot during acceleration than the outer point. Should mean less squat. We'll see.

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A peek into the decision process, obviously not much meaning easily visible from the raw data but it shows the nearly 35 suspension point iterations tested in CAD before going ahead with fabrication. 

 

et1uq9w.png

 

 

A point of interest brought up by Jeff in our conversations about the trailing arm angle and resulting forces. He wagered the front suspension made nearly the same angle as our rear suspension and therefore would carry cornering loads similarly. I didn't think they were too similar until I overlaid the front on the rear! New perspective, haha.

 

SAisDc4.png

 

With the final geometry worked out we turned to FEA for the detail design, lots of iterations resulted in some additional gussets and bends on the trailing arms but, more dractically changed the moustache box which is looking more like a bow-tie box these days. We had to reduce/eliminate the in situ accesss of the diff mounting bolts but it was that or make the box the lowest point of the car  :hmm:

 

 

2Qs7gTC.jpg

 

9aXxhJ9.png

 

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pzsLnDI.png

 

The last major change those far is a bolt on shock mount, this will be a bit more work to implement but gives us a lot of future proofing for some ideas we've been toying with implementing  :D

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Man that looks sexy! How about the stock roll bar configuration, does that remain the same? 

 

 

Funny you bring that up.  I've always listened to Keith on the Realm and never ran a rear bar.  My Tan car had one on it when I bought it.  I left it on for a while just to see what I thought.  Although I never tired it in competition I feel it did make the car over steer to much.  We should retain the option for a rear bar, but you might try pulling it and seeing how you like it.  

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Using a rear sway bar on a 510 is not a must. You can adjust the car's handling balance with spring rates.

 

If you remove the rear bar from a well sorted car you will need to increase the rear roll stifness or reduce the front to bring the handling balance back to neutral. To counteract the sway bar removal you generally increase the spring rate on the end of the car that the bar was reoved from. 

 

My latest road racing 510 has no rear sway bar. Initially I set the car up with a 380# rear wheel rate and 400# springs up front with a 1.125" front sway bar. I run the rear springs in stock location and have the highest spring rate rear springs I could find that would fit in the car. I ended up dropping the front springs to 350# to balance the handlng. 

 

You can set-up a car with no rear bar, but the traditional rule of thumb of matching wheel rates F&R will need some adjustment.

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Using a rear sway bar on a 510 is not a must. You can adjust the car's handling balance with spring rates.

 

If you remove the rear bar from a well sorted car you will need to increase the rear roll stifness or reduce the front to bring the handling balance back to neutral. To counteract the sway bar removal you generally increase the spring rate on the end of the car that the bar was reoved from. 

 

My latest road racing 510 has no rear sway bar. Initially I set the car up with a 380# rear wheel rate and 400# springs up front with a 1.125" front sway bar. I run the rear springs in stock location and have the highest spring rate rear springs I could find that would fit in the car. I ended up dropping the front springs to 350# to balance the handlng. 

 

You can set-up a car with no rear bar, but the traditional rule of thumb of matching wheel rates F&R will need some adjustment.

 

Is that the setup you ran in the SCCA runoffs? 

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Is that the setup you ran in the SCCA runoffs? 

 

Yes, that was the set-up I ran at Indy. The rear springs are 1450# in stock position (1450 / 3.8 = 382#). The balance was good. The engine was not very strong, my best trap speed was only 108mph. 

 

I spent the week chasing gremlins, which resulted in a poor qualifying effort. The high point of the race was receiving the Sunoco Hard Charger Award for moving up 11 positions.

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Yes, that was the set-up I ran at Indy. The rear springs are 1450# in stock position (1450 / 3.8 = 382#). The balance was good. The engine was not very strong, my best trap speed was only 108mph. 

 

I spent the week chasing gremlins, which resulted in a poor qualifying effort. The high point of the race was receiving the Sunoco Hard Charger Award for moving up 11 positions.

 

 

You should post a thread talking about your racecar and the season.  I would love to read it!!! 

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From what I understand there are advantages and disadvantages to not having a rear sway bar. At low speed cornering like on an auto cross track a bit of trail through can help with accelerating earlier out of corners. In high speed cornering though it tends to make the car feel more responsive but less less stable. Troy holds track records all over the left coast and he uses an adjustable rear sway bar. 

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From what I understand there are advantages and disadvantages to not having a rear sway bar. At low speed cornering like on an auto cross track a bit of trail through can help with accelerating earlier out of corners. In high speed cornering though it tends to make the car feel more responsive but less less stable. Troy holds track records all over the left coast and he uses an adjustable rear sway bar. 

 

 

I'm not going to disagree with you on the rear sway bar thats for sure.  Setups are also personal preference.  No comment on Troy.  

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You should post a thread talking about your racecar and the season.  I would love to read it!!! 

 

Jeff, 

 

I really need to tell the story of getting it ready and racing it at Indy. The car’s SCCA logbook was issued in 2001 based on only the cage being installed. I'm the fourth (technically 3rd) owner since then and it was still unfinished when I took possession. It wasn't until June of 2017 when it made it to the track for the first time. 

 

It would be a tale of struggle, frustration, bewilderment, perseverance, destruction, heartbreak, elation and every emotion in between.  

 

I'm not going to disagree with you on the rear sway bar thats for sure.  Setups are also personal preference.  No comment on Troy.  

 

The issue to use a rear sway bar or not has been around for years and will likely continue for years. 

 

 

One plus to using a rear sway bar is ease of adjustability at the track. If the car is under steering slightly, reposition the links to add more rear roll stiffness makes for easy adjustment. Without a sway bar it means swapping springs, then adjusting ride height and re-scaling the car. 

 

 

Decades ago when I first started racing a 510, I used a rear sway bar. The car would understeer like crazy, so I increased the rear bar diameter to help correct the problem. That helped allot, but it also created a situation where the inside rear wheel was getting seriously un-weighted. 

 

 

The car was running a welded diff which added to my understeer handling issues. It wasn't until I broke the welded diff and replaced it with an open one did I realize what was going on. Running the open diff made it impossible to put down any power in a turn. The inside rear was so unweighted that it all but off the pavement and would light-up like a funny car burnout anytime I put power to it.

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Sorry Jeff, I just couldn't resist.  :poke:

 

 

Although I've changed my mind slightly.  Yes Troy wins against other vintage cars.  Which is still something.  My setup is a copy of Keith from The510realm who has many many race titles from the many different class including the unlimited class.  My favorite story is his hill climb victories.  Not only did he win the unlimited class but he was also the only guy in that class that drove their race car to the hill climb, jack it up and swap on the race tires then at the end of the day after winning, swap street tires on and drove it home.  The only car that ever beat him up that hill was some years an open wheel car would show up and he couldn't quite beat that car.  To me that's a real win.  Building a machine that not only can be other 510's but that can beat everything.  That's what I want to build, I don't want to participate in reliving 1971 over and over.  

 

 

 

 

Jeff, 

 

I really need to tell the story of getting it ready and racing it at Indy. The car’s SCCA logbook was issued in 2001 based on only the cage being installed. I'm the fourth (technically 3rd) owner since then and it was still unfinished when I took possession. It wasn't until June of 2017 when it made it to the track for the first time. 

 

It would be a tale of struggle, frustration, bewilderment, perseverance, destruction, heartbreak, elation and every emotion in between.  

 

 

The issue to use a rear sway bar or not has been around for years and will likely continue for years. 

 

 

One plus to using a rear sway bar is ease of adjustability at the track. If the car is under steering slightly, reposition the links to add more rear roll stiffness makes for easy adjustment. Without a sway bar it means swapping springs, then adjusting ride height and re-scaling the car. 

 

 

Decades ago when I first started racing a 510, I used a rear sway bar. The car would understeer like crazy, so I increased the rear bar diameter to help correct the problem. That helped allot, but it also created a situation where the inside rear wheel was getting seriously un-weighted. 

 

 

The car was running a welded diff which added to my understeer handling issues. It wasn't until I broke the welded diff and replaced it with an open one did I realize what was going on. Running the open diff made it impossible to put down any power in a turn. The inside rear was so unweighted that it all but off the pavement and would light-up like a funny car burnout anytime I put power to it.

 

 

 

We want a thread, we want a thread, we want a thread!!!!!  I just read the preview and I want to read more about your racing! 

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Although I've changed my mind slightly.  Yes Troy wins against other vintage cars.  Which is still something.  My setup is a copy of Keith from The510realm who has many many race titles from the many different class including the unlimited class.  My favorite story is his hill climb victories.  Not only did he win the unlimited class but he was also the only guy in that class that drove their race car to the hill climb, jack it up and swap on the race tires then at the end of the day after winning, swap street tires on and drove it home.  The only car that ever beat him up that hill was some years an open wheel car would show up and he couldn't quite beat that car.  To me that's a real win.  Building a machine that not only can be other 510's but that can beat everything.  That's what I want to build, I don't want to participate in reliving 1971 over and over.

 

No doubt Jeff, Keith (bertvorgon) and his turbo L20 are legendary. I got to meet him when he came out for the vintage races at Laguna Seca. Love reading his Rolling Dyno thread.

 

I think you and I are on the same groove of building an unlimited class 510 that can beat everything. Although I respect the "all things equal" aspect of vintage racing, I just don't do well with not being able to improve performance here and there  :rolleyes: Okay, everywhere. It's interesting that neither of us have flares our cars though. Even though I know if I want to be seriously unlimited competitive it's a must, but for me that's an esthetic line I'm not willing to cross... just yet  ;)

 

 

 

The issue to use a rear sway bar or not has been around for years and will likely continue for years. 

 

One plus to using a rear sway bar is ease of adjustability at the track. If the car is under steering slightly, reposition the links to add more rear roll stiffness makes for easy adjustment. Without a sway bar it means swapping springs, then adjusting ride height and re-scaling the car. 

 

Decades ago when I first started racing a 510, I used a rear sway bar. The car would understeer like crazy, so I increased the rear bar diameter to help correct the problem. That helped allot, but it also created a situation where the inside rear wheel was getting seriously un-weighted. 

 

The car was running a welded diff which added to my understeer handling issues. It wasn't until I broke the welded diff and replaced it with an open one did I realize what was going on. Running the open diff made it impossible to put down any power in a turn. The inside rear was so unweighted that it all but off the pavement and would light-up like a funny car burnout anytime I put power to it.

 

Jumping from a welded to an open diff must have been a night and day shock, and I can see how it would expose the light inner rear wheel. What is your experience with using body/roll trail through as an advantage in accelerating early out of corners? I believe I had a conversation with Kieth about this a while back and he almost convinced me to take my rear bar off. 

 

Tom Anker's SCCA 1991 National Champion 510 had absolutely no body roll. Looked like his suspension was more go-kart than car, but damn that car could fly through corners.

 

 

I honestly think that set up right, either configuration can be made to work really well. 

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