74 GTV Suspension Upgrades - Alfa Romeo Bulletin Board & Forums

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post #1 of 40 (permalink) Old 01-07-2017, 08:43 AM Thread Starter
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74 GTV Suspension Upgrades

Hi,

I thought it would be a good idea to share my suspension upgrades - both to garner advice and opinions, and hopefully to act as a reference for others in the future (good or bad).

After flirting with the idea of racing by attending track days and autocross events, I decided to go all-in. However, I'm still trying to balance being fast with looking good

This winter's plan is as follows:

- Install a 4.1 diff with 47% lockout ratio
- Install panhard setup
- Install drop spindles
- Install adjustable upper control arms
- Replace front ATE calipers with Aluminum Brembo's

I'll post some pics of my progress to date. Thanks in advance for your opinions/advice.

Michael.
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post #2 of 40 (permalink) Old 01-07-2017, 08:57 AM Thread Starter
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Got everything apart and cleaned up inside the wheel well. The paint and undercoating is holding up really well after 14 yeears.
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post #3 of 40 (permalink) Old 01-07-2017, 09:01 AM Thread Starter
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Suspension parts

These were all sandblasted and then painted with POR-15 in 2003-2004. With a little degreasing they look like new.
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post #4 of 40 (permalink) Old 01-07-2017, 09:18 AM Thread Starter
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Lower wishbone

While I have everything apart, I'm going to replace all the bushings. I'm not going to do any final torquing on re-assembly until the suspension is under load, but am surprised to learn that there's no documented torque specs for the lower wishbone to the dog-bone.

Here's a good thread on this:

105 Chassis Front Suspension Questions
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post #5 of 40 (permalink) Old 01-07-2017, 12:45 PM
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Quote:
Originally Posted by MidLifeCrisis View Post
These were all sandblasted and then painted with POR-15 in 2003-2004. With a little degreasing they look like new.
Nice, but you will not be needing the brake disc backing plate . First thing to remove when converting a road car to a track car, UNLESS you cut a hole in it and use it to feed ducted air to your brake disc.
Pete

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post #6 of 40 (permalink) Old 01-07-2017, 12:56 PM Thread Starter
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Backing Plate/Dust Cover

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Nice, but you will not be needing the brake disc backing plate . First thing to remove when converting a road car to a track car, UNLESS you cut a hole in it and use it to feed ducted air to your brake disc.
Pete
Thanks... didn't even think of that. I was planning on ducting some air to the calipers/disc. Is it easier to mount something with the dust cover in place?
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post #7 of 40 (permalink) Old 01-07-2017, 01:43 PM
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Quote:
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After flirting with the idea of racing by attending track days and autocross events
- Install a 4.1 diff with 47% lockout ratio
If you will be using the car for racing/autocross, are you sure you want to replace your 4.56 diff with a 4.10? That swap is terrific for a street car; the 4.56 is too low (numerically high) for modern highway driving, especially when paired with a 2 L engine which delivers plenty of torque (the 4.56 made sense when Alfas came with 1.3 or 1.6 L engines).

For racing/autocross you want the engine operating at high rpms where it makes more power, and that's what a 4.56 (or 5.xx) will produce.
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'65 Guilia Sprint GT
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Last edited by Alfajay; 01-07-2017 at 01:47 PM.
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post #8 of 40 (permalink) Old 01-07-2017, 01:53 PM Thread Starter
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Lower Wishbone Bushings

I was really disappointed with the quality of the "new" bushings I bought from a major supplier. Even looking at the unopened packaging gave me pause since it had some kind of debris in each. Also, two of them had metal turnings still in the package and/or attached to the bushing.

The first one went together OK, but the second one I tried would not go onto the dog-bone. I thought I could coax it with the press, but it just pushed a ridge into the inside of the bushing to the point where I was going to break something.

I'm a bit of a pack-rat and found two of these still in packaging from 2003 when I last did the suspension work. I used both of these and found I nice tolerance fit. Thank goodness the last of the 4 "new" ones I bought seemed to fit. Check out the comparison. First the "new" ones... I don't know what high school shop class put these together but I would have given them a "C".
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post #9 of 40 (permalink) Old 01-07-2017, 01:56 PM Thread Starter
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Lower Arm Bushings

Here's some pics of the ones I bought in 2003...
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post #10 of 40 (permalink) Old 01-07-2017, 02:09 PM Thread Starter
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4.1 Diff

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If you will be using the car for racing/autocross, are you sure you want to replace your 4.56 diff with a 4.10? That swap is terrific for a street car; the 4.56 is too low (numerically high) for modern highway driving, especially when paired with a 2 L engine which delivers plenty of torque (the 4.56 made sense when Alfas came with 1.3 or 1.6 L engines).

For racing/autocross you want the engine operating at high rpms where it makes more power, and that's what a 4.56 (or 5.xx) will produce.
Great question.

I've found that the tracks in my region require me to gear-up slightly. For example, at the newly re-done Thompson Motorsports Park in Thompson, CT, I'm going around the entire track in third gear with the exception of the main straight. I have a 1-2-3 distributor and have set the rev limiter at 6,700 rpm's. I hit this on the shorter back straights quite often and hope that the overall gearing will put me a little lower in the power band and help me resist the temptation of shifting into 4th for two seconds. I also think that with the suspension upgrades, I'll be able to enter the main straight on these tracks with more speed and may need the higher top-end.

My friends and I go to Sebring for the 12 hour race every year and in the past one of us has always had a car on the track running with HSR. Expecting to bring my car there this year, I definitely wanted the 4.1 diff. Unfortunately, it looks like HSR is not doing the support races for the 12 hour race this year, so I think we're headed to the Mitty.

Thanks.
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post #11 of 40 (permalink) Old 01-07-2017, 02:35 PM
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I've found that the tracks in my region require me to gear-up slightly.
OK, sounds like you have thought it through. Good luck with your modifications!

Jay Mackro
San Juan Capistrano, CA

'63 Guilia spider
'65 Guilia Sprint GT
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post #12 of 40 (permalink) Old 01-07-2017, 03:23 PM
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Quote:
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Thanks... didn't even think of that. I was planning on ducting some air to the calipers/disc. Is it easier to mount something with the dust cover in place?
Well you could cut a large round hole in the dust cover, and then weld a short tube of the same diameter to it and this is where you attach your ducting hose. Where that hole and tube is located I'm not sure and you would have to do some research and ensure full suspension movement and steering angles are not compromised.

We though found that as long as your ducting hose points somewhere approximately towards the caliper/disc it worked, minus the dust cover.
Pete

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post #13 of 40 (permalink) Old 01-07-2017, 05:53 PM
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I hesitated for years after I built a 4.1 axle for my Spider. I reasoned that as my motor made good power to 7000 rpm I would never max it in 5th. In reality it went to 7000 easily in 4th but did not pull hard above 100 mph when I shifted into 5th. I finally installed the 4.1 last year at the same time that I got my 45DCOE's sorted out. Now it still pulls hard to 7000 in 4th but now I am doing 110 mph. In my case the 4.1 is better suited to my motor.
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post #14 of 40 (permalink) Old 01-10-2017, 09:08 AM
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the 4.1 will reduce revs by 10% for any given speed, what that will do for lap times, hard to say. alternately (or in addition) you could easily raise the rev limiter. if need be, as ed indicated, engine will spin 7K+ easily and safely.
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post #15 of 40 (permalink) Old 01-10-2017, 04:50 PM Thread Starter
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Rev Limiter

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the 4.1 will reduce revs by 10% for any given speed, what that will do for lap times, hard to say. alternately (or in addition) you could easily raise the rev limiter. if need be, as ed indicated, engine will spin 7K+ easily and safely.
Great torque out of this engine and want to ensure longevity. Focused on handling right now then may get back to engine tweaks.

Thanks.
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