Alfa Romeo Forums banner
1 - 12 of 12 Posts

·
Premium Member
Joined
·
1,064 Posts
Discussion Starter · #1 ·
I have a question about indexing Torsion bars on the transaxle cars. I would like to know if anyone has an approxiamate value for the change in ride height of the front end when the lower Control Arm is pulled out of the torsion bar and indexed one tooth in any direction.

Spring rate should have nothing to do with this, any bar will twist until it supports the load then stop. As long as we are talking about the same torsion bar.

I am aware that this is not the factory way of adjusting ride height. That way involves rotating the torsion bar to take advantage of the mismatch in the splines on either end. There are 35 teeth on the front and 34 on the rear of the bar. The manual says rotating the bar one tooth changes the ride height 0.10"

I am geussing that the answer may involve the number of splines and the motion ratio of the front suspension.

Anyone care to weigh in?

Greg
 

·
Registered
1976 Alfetta GT, 2018 Giulia Sport
Joined
·
1,785 Posts
Moving the T Bar 1 spline only at one end (control arm in this case) and not the other is a gross ride ht. change of over 1". Or looking at the control arm while making the change it is a bunch of degrees (15-20?) off. This info comes from adjusting my Alfetta GT and I assume it applies to the Milano.
Here is my method of ride ht change:

Only keep track of spline changes at the back end, don't worry about the control arm. After changing 1 spline at the back you put the bar back into the control arm. The TBar is designed so that when barely engaged at the back end it is free of the control arm. If you are + or - 1 spline the control arm will be grossly wrong so gently pull out the TBar (DON't remove it at the back end), rotate the control arm to where it looks about right and reassemble. Then re-assemble the ball joint, lower the car and check your height change.

I got bored the last time I changed the T Bar in my Alfetta and discovered this.
 

·
Registered
Joined
·
173 Posts
indexing torsion bars

If it is 35 splines, that works out to 10.29 degrees. Measure from the inner LCA bushing center to the ball joint center. Double that x PI /35 should give you the change within a very small fraction of an inch.

In Greg's write up, he says 25 splines, or 14.4 degrees. I'm not sure who is right, so do the right math after you double check the number of splines (I don't remember).

Also, Greg's method doesn't sound like it will work on cars with larger than 25.4 mm torsion bars. If you are using 27, 30, or 33 mm bars you will need to lift the engine and put the LCA bolts in from the engine side (this is what I did on my ITB Alfetta back in the day). You will also have to remove the LCAs to rotate the torsion bars to change the ride height. So, counting splines might be your only option.

If you don't have the directions, take twice the LCA length x PI / # of splines at the front and rear of the torsion bar. The difference is the change from moving the Torsion bars one spline at each end.

If you are changing bar size, your initial setting is a guess. Don't put the shocks or front anti-roll bar back on. Do both sides the same, bounce the car, decide the change, calculate the # of splines, then make the changes to both sides, reassemble and remeasure. If you are good, install the shocks and front anti-roll bar.

It makes coil-overs mighty attractive... but they are not legal in any Vintage, SCCA road-racing or SCCA Auto-x class.

Chris
 

·
Registered
Joined
·
4,075 Posts
25 may have been a typo I don't remember. Of course with the method I use it doesn't matter. My method will not work with bars larger than 25.4mm.

Greg
 

·
Registered
Joined
·
173 Posts
Greg Gordon-

Your method sounds great. The only time I have done this was on my race-car, so I needed bigger torsion bars. On a street car, your method would rock.

Thanks for the clarification.

~Chris
 

·
Premium Member
Joined
·
1,064 Posts
Discussion Starter · #7 ·
Update. I did change the ride height of the Lemons car in an attempt to correct the corner weight.It has 27mm torsion bars so the bar cannot be pulled out of the rear torsion bar mounting as it is of a larger diameter that the spline mounting. I used a combination of Gregs method and what other people had suggested.

I needed to lower the Left Front. I disconnected the antiroll bar, tie rod end, damper and upper ball joint. Unbolted the Lower Control Arm (LCA)and knocked it of of the torsion bar. Took the bar out of the rear mount after marking it position in the rear mount and then rotated it 2 splines then bolted everything back together. It changed the ride height about .20" just as the manual said it would. Pain in the butt but it gets easier the more you do it.

Greg
 

·
Registered
Joined
·
173 Posts
Ep gtv6

Hey Greg!

Are you racing the EP GTV6 at all? It seems that you are focusing on the Lemons Milano. I am considering building an EP car, either a GTV6 or an Alfetta GT. There is a guy here in my region that is dominating EP with his GTV6. I would love to hear what you think about running an Alfa in EP.

~Chris
 

·
Richard Jemison
Joined
·
8,258 Posts
Ep gtv6

There is a guy here in my region that is dominating EP with his GTV6.
Al Mitchell`s car has been in development since 2001 or so. Al uses only the best technology, and spends long hours in his shop keeping it in top shape.

He`s away this season on a Medical Ship around So. America.

His wife drives an ITS Milano Verde also.
 

·
Registered
Joined
·
173 Posts
Ep gtv6

Richard-

I was reading through race results and saw Al Mitchell and Melanie Mitchel, but did not make the connection. It must be great to be married to some one with the same passion for racing!

I raced years ago and am looking at doing it again, so was researching what class might be best for an Alfa. It seems that Milanos are hopelessly outgunned in ITS. Reading the EP rules, I would think an Alfetta would be better than a GTV6 given its 350 lb lower minimum weight and more liberal preparation rules. But Al is murdering (5 seconds a lap faster than the next fastest car EP car at CMP) his EP competition. What am I overlooking? I assume the GTV6 will be cheaper to run because of the lower state of tune.

Any input you have is much appreciated.

~Chris
 

·
Premium Member
Joined
·
1,064 Posts
Discussion Starter · #11 ·
Hey Greg!

Are you racing the EP GTV6 at all? It seems that you are focusing on the Lemons Milano. I am considering building an EP car, either a GTV6 or an Alfetta GT. There is a guy here in my region that is dominating EP with his GTV6. I would love to hear what you think about running an Alfa in EP.

~Chris
Hi Chris,

I have raced the GTV6 about 4 times and spent a few long weekends at track weekends testing. The car was originally an ITS car and Vick Autosport converted and built it into an EP car for a women in Texas. She had mixed results because the car was suffering from some teething problems in the two years she ran it. Then it sat for at least two years before I bought it.

Crazy optimist that I am I sent it to the race shop where I had purhased my Berlina and they prepped it for the Targa 66 weekend at Palm Beach Raceway. It was great, well untill I cracked the clutch cover, i had a cover overnighted from home fixed it, and promptly blew up a dried up front Guibo at 7000 RPM sending some shrapnell through the bellhousing. It was a huge leap to think that a car that had sat that long would be track ready. Also I slowly figured out that the reason the PO had a 6000 RPM rev limiter chip in it which I prompty discarded was that the driveline was not at all right.

I compounded the mistake of not going over the car thoroughly enough by having the Florida race shop work on the car. They were useless for a transaxle car and actually managed to assemble the driveshaft completelty wrong. More trouble.

After I brought the cars to NY and went over them myself things got better but I still have a lot to do for reliability and development which I am working on now. But the LeMons racing has taken a lot of time. MY Lemons team looks like we have captured the North East regional championship and are still in the top 5 nationally. So we are going to the season closer in Texas in December.

I have run the car exclusively in Vintage with the SVRA. It is competitive there if I can work out the Gremlins. I think it can be a competitive platform to run in the SCCA as well. As stated earlier the Alfetta chassis is a bit light er and looks Identical to the GTV6. No comment. There was a change to the engine development rules that upped the potential power a little while back for the 2.5 Liter motor. Thank Allen for that. It will be a long time before I can take advantage of that though. It is a big undertaking to develop an EP car on this platform but the parts are available. I love the car though, It has great balance and sounds like nohing else out there.

As Richard stated Allen Mitchell has done the time and work and research to develop his car and is a great driver and competitor. There are a few other guys running this car in EP look them up and ask them about it they are all great guys and share info. Richard is also a wealth of information. Check out the yahoo alfa racing newsgroup. I am actually reading through it from end to end now. Also the GTV6 site is a good source of info.

Greg
 

·
Registered
Joined
·
173 Posts
Thanks Greg!

Thanks for the info. I did not know about the Yahoo group. I will check it out. Congrats on your LeMons success. I have read all your threads here. I hope you do well in TX. It is great to see a Milano do well.

It is a big jump from ITS to EP. I never had drive shaft issues in my IT car and didn't do anything special. I replaced all the guibos before I ever took the car to the track, though. But, funny thing, I used a 6000 rpm redline too. There was little point revving a stock 2 liter higher. I built the engine myself and Dan Marvin did the head. I let Al Leake drive it once and he revved it to 7200! Clearly he was looking for the power to come in... He was used to his HP Guilietta. The brakes took a lot more sorting. I think I still have a few sets of rear calipers in my garage. :p

Is your car at the minimum weight? What does a set of tires cost and how often do you need fresh ones? My other option is to build a Spider for ITB. It would be cheaper, it's familiar ground, etc., but I'd like to build something faster and eligible for national competition. IT is also a little like Spec Miata... lots of dirty driving. I was doing bodywork after every race.

I too love the sound of the V6. Honestly, I'm leaning more that way just for the sound! I reread the rules, and programmable EFI appears to be legal. You need to run the stock intake manifold, plenum and throttle body, but can match ports. Also, allowable cam lift is .500" not .445". Maybe that is enough to get competitive power with no porting. You would need 250 hp to match the power to weigh ratio of the EP Alfetta. Richard would have a better feel for this. I am guessing that reliability of the V6 should be pretty good under 7000 rpm.

Do you have pics of your EP car here on the board? I'd love to see it.

Thanks for your help.

Chris
 
1 - 12 of 12 Posts
Top