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Setting ride height for 330 GTC

Discussion in 'Vintage (thru 365 GTC4)' started by JimEakin, Feb 26, 2021.

  1. JimEakin

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    My 330 GTC came with 205/70VR14 tires. I later learned that the correct tire is the 205VR14, which is an 80 profile tire. I've seen from posts on other cars that most people fit the 205/70 tire because it is more readily available.

    According to the specs in the Angelo Wallace manual, my car has been lowered about an inch in the front . The rear is somewhat lower, and the suspension hits the stops sometimes, with the exhaust dragging on bumps.

    Jumprun here on FChat recommends staying with the 205/70 tires - better handling. TTR (Timo) is recommending that I go all the way back to "original" ride height and invest in the correct tires. However, TTR does have custom spacers for the coil overs so I can go whichever way I finally decide.

    The 80 profile tires are over an inch and a half taller, which would require a higher car to make room in the wheel wells. A drawback of the 80 profile tire is that the car will lug more when taking off as it has a very tall first gear (but the engine runs at lower revs at freeway speeds).

    My plan is to stay with the 205/70 tires, keep the front at its current height, and adjust up the rear to match. I plan to set the height with a couple of my buddies sitting in the car, and with a full tank of gas.

    I have always had improved handling when lowering a car, because of the lower center of gravity. Of course, thought must be given to the range of travel and alignment of the suspension. My goal is a fun-to-drive car. (Also, I just bought new fronts because I thought the 80 profile tires wouldn't be available for quite a while.)

    What say you about the 330 GTC?

    1. Stay with 205/70 tires and set the rear ride height to level the car.

    2. Must return to original specs and tires.

    3. Other?
     
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  3. miurasv

    miurasv F1 Veteran

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    #2 miurasv, Feb 26, 2021
    Last edited: Feb 26, 2021
    Get the correct 205 VR14 tyres. Sell the 205 70 VR14 tyres.

    I don't think most people fit the 205 70 14 tyre at all as the correct full profile tyre is readily available for the 330/365 GTC/GTS.

    I believe people have fitted 215 70 VR15 tyres to 330 GT 2+2s and 500 Superfasts as the correct full profile 205 VR15 was not available, but the difference in the diameter is smaller in that case. Longstone now have the correct full profile tyres for the 330 GT 2+2 and 500 Superfast.
     
  4. Ed Niles

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    FWIW, I doubt that you could feel the difference..
     
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  5. miurasv

    miurasv F1 Veteran

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    #4 miurasv, Feb 26, 2021
    Last edited: Feb 26, 2021
    The exhausts might feel the difference when scraped due to the lowered body height.

    Speedo accuracy will also be adversely affected by the wrong diameter tyres.

    Sounds like you need to get the suspension checked and corrected as well.

    Don't forget you need the 7" wide 72 spoke Borrani RW 4039s to replace the 6 1/2" wide 60 spoke RW 3874s too.
     
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  6. JimEakin

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    Thanks, Ed. This is the perspective I was looking for.
     
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  8. 1monza

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    Often I'll put the 215/70VR14s on a car because the standard will rub the fenders when turning. The 215/70VR14 is kind of a compromise where it is not quite as tall as the 205VR14 but is also a little wider and fills in the fenders better then the undersized 205/70VR14.
     
  9. DWR46

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    Jim: Remember, opinions are like armpits, everybody has them. However the other posters have given you good advice.

    1. The funds spent for the correct wheels and tires will easily come back to you when the car is sold. People today will immediately discount a car with obviously wrong components.

    2. As others have mentioned, a lower ride height will bring a myriad of problems with it.

    3. I am not aware of a easy way of lowering a GTC suspension. This means you probably have sagged front and possibly rear springs, or the rear upper shock mounts have broken away from the frame. All of these are common GTC problems.

    4. Ferrari, in this era, had very smart engineers. They knew what they were doing. They picked the factory ride height for a reason. I would highly recommend staying with the factory ride height.

    5. If you have sagged springs, all is not lost. I believe new springs are available today, but in the past, we machined spacers to place on the lower spring mount over the shocks. You may have to do some measuring to get the correct motion ratio for how far the shock travels versus wheel travel, to determine the thickness of the spacer needed. Amazingly, once an original GTC spring takes a set, it seems to stay there, so I would bet a set of spacers to restore the ride height will make the car correct for many years.

    6. After the ride height is corrected, you will need to re-align the suspension as the change in ride height will change the alignment.
     
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  10. JazzyO

    JazzyO F1 World Champ

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    Return to original specs. I loved the way my 330GTC drove. She taught me a great deal when I took her down a Swiss mountain pass a couple of days after having bought her. Fantastic driving machine, great balance and sitting on the rear axle is wonderful.

    One thing that enhanced my driving experience is that I changed the throttle angle so that it was easier to heel and toe under hard braking. Using three pedals at once is most satisfactory. :)
     
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  11. 15765

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    If you need them I have a spare set of new 330 GTC front and rear springs I purchased many years ago. They should be checked for weight rating because when I bought them for the GTC they did not have the part number tags on the and I didn't purchase them from a Ferrari Dealer
     
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  13. barchetta

    barchetta Formula Junior
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    Not to derail the thread, but regarding shock mounts on the 330GTC/330GTS:

    http://www.tomyang.net/cars/ferrari.html?http://www.tomyang.net/cars/ferrari1306.htm
     
  14. DWR46

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    Barchetta: Exactly, that is the factory "fix" for the front suspension. I wrote a tech article in 1976 for the rear suspension that was published in the FCA Prancing Horse magazine.
     
  15. 330BRC

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    My $.02 worth is that the original series tires are the ones that look right. They fill the wheel wells. The 70 series tires look a little awkward and undersized. I’ve had both on my GTC. Having said that, both sets were XWX’s and neither set were really great performance tires to begin with. I settled for the look.
     
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  16. JimEakin

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    #13 JimEakin, Mar 3, 2021
    Last edited: Mar 3, 2021
    Hi Chuck,
    Thanks for the suggestion. I use the old :\"bounce the suspension" and it seems that the springs and shocks are fine. May need spacers. Timo looking into that.
     
  17. JimEakin

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  18. JimEakin

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    Hi DW,
    I took my car over to Timo's shop yesterday. Based on his review, it does look like the upper shock mounts on the rear have broken. I'll be taking the car over to him in a while to have him make the fixes. Timo did say he has been talking to you about my car. Thanks for the help.
     
  19. JimEakin

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    Hi Brian,

    I just found out that I don't have the correct wheels for the car, anyway. (Seems like my car has been used for spare parts and parts swap over the years it was stored for a customer.) I'll change to the correct tire size if and when I change over to the correct wheels.

    Tom Martinez (Jumprun here on F-Chat) says he's tried both tire sizes and preferred the smaller tire. I really want to be able to enjoy reasonable drives (not boy racing with this car) so I'm not sure I'd notice the difference in handling the way I plan to drive. Also, I'm thinking of keeping the car a little on the low side so that the tire/wheel well appearance doesn't look that awkward. I do need the rear raised as the car is just sitting too low as it is now.
     
  20. TTR

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    I’m preparing to help Jim get his 330 GTC suspension ride height and other related things sorted, but before getting started I would love to get some reference from other cars, mainly their “ride height” measurements/readings.
    If any owners and/or caretakers would care to measure, record and provide me their findings, it would be very helpful.

    The measuring itself, depending on the environment and preparations, may not take more than few minutes, but it would best if the car is sitting on a flat, even surface, like on garage/shop floor or 4-post lift ramps “fully loaded”, i.e. 2 adult passengers, fuel tanks full, spare tire & tools in the trunk) on all four tires (tire or wheel sizes or types are irrelevant and will not have any effect my research).
    If a subject car is measured with only one or without any passengers, less than full tank, etc, notes to that effect, along with overall condition of shock mount bushings and spiring (rubber) insulators, would be helpful.

    I’ve attached couple of photos of my drawings showing the two measurements (“A” and “B”) needed from each of four lower suspension control arms + one photo showing how to measure (photo subject is a Daytona*).
    Basically, using a small, 10”-12” long, machinist (steel) ruler or something similar with readout in millimeters, starting at the end being zero, set on the floor or other flat, even surface, going straight up to the center of bolt head, either the inner bolt (pivot point next to the chassis oval tube) or the outer bolt (next to the ball joint in the front and pivot point of the upright in the rear).

    Anyone willing to assist by measuring their car can send results or request my direct email via PM if they so prefer and any information regarding the vehicle itself or the owner will be treated with strict confidentiality.
    This research will likely be ongoing even after we’re done with Jim’s car, so any measurements provided in the future will also be helpful/useful.

    * Additionally, I’ve been conducting similar research on 365 GTB/4s (Daytonas) for few years already, so identical measurements from any such would also be greatly appreciated.

    Thank you.

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  21. Tinbender

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    I don't understand how the tire size will not affect this measurement.
     
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  22. gcalex

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    I believe Timo is trying to establish the deflection angle of the lower A-arm.

    If the suspension is set as "factory spec", this angle should be the same, regardless of what tires are fitted.

    Kudos to Timo, as I think this is exactly the right spec to try and hit... :)
     
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  23. JimEakin

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    The tire size will affect each ‘A’ and ‘B’ measurement, but the difference between these measurements will be independent of tire size. The A-B measurements are noted in Angelo Wallace’s Assembly manual for the 330 GTC.

    Ride height will be affected by tire size, so should be noted, too.
     
  24. TTR

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    Sorry guys, perhaps I should’ve specified that for my research purposes, I’m only focusing on or interested in the difference between “A” and “B”, not the actual total of each measurement.
    Yes, the total measurement will be affected by tire/wheel size, but the angle of the the control arm, which I’m trying to collect data on will not.

    For my purposes the car could sit on 14” x 5” with 80-series or 16” x 8” with 50-series wheels and tires or perhaps have some of those “roller-dollies” placed under the each tire (assuming the “dollies” are all equal height) and the “difference between “A” and “B” ”, if any is present, will not likely be detectable/measurable within given scale of +/-1 mm.

    Technically speaking, one could even use, let’s say 4” tall piece of some metal/plastic/wood/etc block or extension between the floor and ruler/tape measure, even if neither has a scale that starts at the very end, as long as the “block/extension” and floor/surface are flat/even and “block/extension” is placed in the the same way for each measurement.
    I will try to post a couple of more photos later today to demonstrate optional measuring methods.

    And thank you for your interest.
     
  25. TTR

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    OK, here’s couple of photos demonstrating various equipment or methods that could be used to obtain measurements I’m interested in, i.e. the difference between “A” and “B”.
    Using various equipment or methods is not going to change the needed outcome as long as same equipment/method is used on all four corners (= eight measuring points) in exactly same way and the car sits (preferably “fully loaded”) on relatively even/flat surface like a smooth concrete floor or ramps of a 4-post lift, etc.

    Another thing I wish to add is that if/when the subject car is “fully loaded” before attempting to measure, it should be rolled (10-20 inches ?) back-and-forth once or twice to allow tires and suspension “settle” under the added weight.
    Same if it has been lifted or supported by a jack or jack stands.

    Hopefully these “instructions” make sense and appear simple enough, but if not, please don’t hesitate to ask here or contact me offline.

    Thank you all.

    P.S. Please respect (my) copyrights for these and previously posted images.

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  26. TTR

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    Correct and thank you.
     
  27. TTR

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    I just realized same measurements from 365 GTCs could be helpful/useful for my research if their chassis & suspension design is identical (or very close) to 330 GTC.
    Do 365 GTCs have their own service/shop manual and/or suspension specs or do they use 330 GTC data/information ?
     
  28. DWR46

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    They use the 330 GTC shop manual. There was a second edition Owners Manual for the 330 GTC that included the 365 GTC.
     

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