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Thread: DIY - Front tube shock conversion

Discuss the Austin Healey Sprite and the MG Midget. Two different but similar cars sometimes referred to collectively as the Spridget.

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    Jedi Warrior
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    DIY - Front tube shock conversion

    Has anyone tried this method?

    https://npmccabe.tripod.com/spritetubeshock.htm

    Looks simple and cheap. I can also see how it could be modified to not require lowering the car.


    5/23/2020 - Updated link: http://npmccabe.tripod.com/spritetubeshock.htm

    Also see my post from 5/23/2020
    Last edited by David_Doan; 05-23-2020 at 02:17 AM.
    David Doan - Frisco, TX
    david at doan.us
    http://doan.us/blog/bugeye/

    1959 Bugeye - AN5L-26655

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    Darth Vader Rut's Avatar
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    Re: DIY - Front tube shock conversion

    David,
    Ive never seen that before and it looks very interesting. I've not tried modifying my Bugeye and I'm very happy with the shocks Peter C rebuilt for me, but I did have a tube shock conversion on a TR4A and it was not near as good as the levers, iirc. The good thing about this set up is its cheap and reversible if things don't go well. Thanks for posting.
    Rut
    Rut, '60 Bugeye, '70 MGB, '62 TR4, '66 TR4a IRS, '67 TR4a IRS, '68 TR4a IRS, '72 TR6

    When I went to school, they asked me what I wanted to be when I grew up. I wrote down 'happy'. They told me I didn't understand the assignment, and I told them they didn't understand life. John Lennon


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    Re: DIY - Front tube shock conversion

    3 of mine are bad, so I would need 4 from Peter - almost $400 with shipping. I think I can do DYI tube shocks for about $100.
    David Doan - Frisco, TX
    david at doan.us
    http://doan.us/blog/bugeye/

    1959 Bugeye - AN5L-26655

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    Re: DIY - Front tube shock conversion

    Quote Originally Posted by David_Doan View Post
    3 of mine are bad, so I would need 4 from Peter - almost $400 with shipping. I think I can do DYI tube shocks for about $100.
    Problem is, you still need the factory shock as a suspension mounting point, meaning if the hole is worn you'll stil need to have it rebushed. The other problem is the way the tube shock is mounted induces flexing in the lower control arm. Those arms tend to develope cracks when dampened from the trunnion much less directly from one side. Sure, that's better than just bolting it up to the side, however; it still doesn't solve the problem. You'd have to install a shock on both sides of the arm in order to reduce dampening flex back to the factory level.

    I'd either make a kit that did away with the stock shock completely and distributed dampening load evenly or I'd stick with rebuilt original stuff.

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    Jedi Warrior BlueMax's Avatar
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    Re: DIY - Front tube shock conversion

    There is one big negative to this concept that this individual has not taken into consideration, un-sprung weight? Look at all the extra components that he has bolted on. What advantage he save in his pocket book he lost in suspension performance…

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    Darth Vader Rut's Avatar
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    Re: DIY - Front tube shock conversion

    David,
    given the other comments I would be very hesitant to do a conversion like this. There are a few things on these cars that really reward you when done as designed. Brakes, suspension, steering, etc. are the things that get a lot of my attention. The rest is important as well, but anything to do with safety...
    Good luck, Rut
    Rut, '60 Bugeye, '70 MGB, '62 TR4, '66 TR4a IRS, '67 TR4a IRS, '68 TR4a IRS, '72 TR6

    When I went to school, they asked me what I wanted to be when I grew up. I wrote down 'happy'. They told me I didn't understand the assignment, and I told them they didn't understand life. John Lennon


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    Re: DIY - Front tube shock conversion

    Guys, Thanks for the advice, warnings, pointers...


    • The front dampers are mechanically sound - no play in the arm, just screwed up damping - so no worries there.
    • The change in un-sprung weight is going to be negligible, one aluminum plate and one steel bar per side. Maybe 1 lbs.
    • The proposed design was actually done by Nial (aeronca65t). He's a been-there-done-that kind of guy who races.
    • If the a-arms crack I'll replace them with newer ones and do the disc brake conversion at the same time.
    • Lastly, the only permanent changes to the car are a coupe extra holes. Everything can be undone.


    From the research I've done, I like Nial's method the best. All of the commercial options require drilling into the A-arms. Morris - a fellow Texan -also did some cool stuff years ago that requires no drilling in the car, but needs a lot more machining.

    I see this project as a win because I can do it myself (so far, I have not paid anyone do to anything), and it is about 1/4th the cost of the Peter C. rebuild which affects my relationship with SWMBO.

    David
    David Doan - Frisco, TX
    david at doan.us
    http://doan.us/blog/bugeye/

    1959 Bugeye - AN5L-26655

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    Great Pumpkin aeronca65t's Avatar
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    Re: DIY - Front tube shock conversion

    LOL.

    I made that webpage 10 years ago.

    The setup has been reliable and simple to set up on my race car. And it's easy to convert back if needed.
    I've done one on a street car too. Works nicely.

    I agree that the added unsprung weight is a minor negative. That could easily resolved that by using lighter wheels (instead of stock Rostyles)....if I wasn't so cheap.

    The conversion is definetly not for everyone; but some of us can't leave well enough alone.
    Cecil Kimber was like that too.

    Nial's #909 Spridget
    My Race Events
    Spridget~MGB~Miata~Austin A35~Midget~Aeronca65T~Super 7~Accord~Chevy TowVan
    Jersey Music!

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    Re: DIY - Front tube shock conversion

    In our wish for a better widget we forget the basics in my mind. The biggest engineering feat is the proper shock valving... The rudiments of attachments etc. is much easier in my mind. I have never experienced a better ride than OEM... anyone else out there is welcome to chime in....

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    Jedi Warrior BlueMax's Avatar
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    Re: DIY - Front tube shock conversion

    For one, I would estimate that the additional shock will weigh at least 3lbs. Then you have the aluminum adaptor, spacers and bolts, washers, nuts add at least another pound for that then you’re up to 4 to 4.5 lbs. On top of it all they attach the shock to the inner finder which is a very weak support with no boxing just stamp sheet metal spot welded together.
    This set up will work but you want see anything like that on a front running racing car.


    .Attachment 26021

    Unsprung weight is a measurement of the weight of everything outboard of the wishbones or suspension links, plus 1/2 of the weight of the wishbones or links and spring/shock. It has a great effect on handling. The diagram below demonstrates why unsprung weight is so important:

    The more weight outboard of the car, the more force bumps exert on the suspension (and ultimately the chassis). This force must be dealt with using springs, dampers and anti-roll bars (described below), and the more force, the more difficult it is to keep the tire planted on the road. This is especially true of lighter weight cars. In the example above, if the car weighs 1000 lbs, a 2G bump would result in a vertical force of 10% of the car's weight. This will at the very least reduce the grip of the car, because the weight of the car is what keeps the tire planted, and pushing a car up into the air with that much force will inevitably reduce the weight on the tire, and hence grip.

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    Re: DIY - Front tube shock conversion

    So David what they are telling you are that Peter C.'s shocks are worth what paid for. You're going to go through and rebuild the rest of the front end, do it right and get a set of Peter C. shocks for the front and rear. You won't believe the difference in how your BE will drive. The Front Shocks are a key component in keeping your wheels on the ground, they are the top of the ssupension not just a piece to dampen wishbone travel. You need to do it right. Front suspension or brakes is not something to experiment with. Explain to your better half as well as yourself, that your life is worth more than $400.
    Jim Gruber - Apollo Beach, FL
    Bugsy I - '68 Sprite w BE Bonnet - Gone but not forgotten
    Bugsy IV - '60 Bugeye - 1,275+.040 and a 5-Speed - CA Car - 2nd Owner from new - 10/12 Painting done, reassembly, cutting, and buffing in progress.

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    Re: DIY - Front tube shock conversion

    Quote Originally Posted by BlueMax View Post
    This set up will work but you want see anything like that on a front running racing car.


    Sounds like he just called Nial a loser.

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    Great Pumpkin aeronca65t's Avatar
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    Re: DIY - Front tube shock conversion

    Billy:

    You are a Troublemaker with a capital "T"!

    Nial (who has won a pile of useless "bowling trophies" with this car and started 4th out of 45 cars at the 2012 PVGP "All MG Race".....with a stock engine)

    Nial's #909 Spridget
    My Race Events
    Spridget~MGB~Miata~Austin A35~Midget~Aeronca65T~Super 7~Accord~Chevy TowVan
    Jersey Music!

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    Re: DIY - Front tube shock conversion

    Quote Originally Posted by aeronca65t View Post
    Billy:

    You are a Troublemaker with a capital "T"!

    Nial (who has won a pile of useless "bowling trophies"

    Bowling trophy? They give you a trophy for takin' out the field?

    Sounds like you'd fit right in dirt track!





    Reminds me of when I bent my brake pedal further to the left so I could do left foot braking.

    Well, we all went into a turn....and when I went for the brake with my left foot.....I accidently hit the clutch..... and piled into EVERYBODY....

    It's funny how frantically pumping the clutch seems to make the car go faster.

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    Yoda Jim_Gruber's Avatar
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    Re: DIY - Front tube shock conversion

    See a case of not reinventing the wheel. I had great results when Peter C redid my shocks 10 years ago. That along with some changes to a newer set of wishbones from a later Spridget certainly helped. When I first got Bugsy he would literally change lanes upon hitting a tar strip the front end was so worn out. Driving was scary to say the least. Changing out to a later set of wishbones, although well worn, lasted me 10 years. Biggest improvement in handling occurred last winter when I sent the wishbones out to Apple Hydraulics to get the wishbones metal bushings replaced, installed new fulcrum pins, and major suspension kit. That made all the difference in the world. AH did some great engineering on this car. Certainly some improvements can be made. I just get worried that messing with some critical components in Suspension or Braking, or Steering could have disastrous unintended consequences.
    Jim Gruber - Apollo Beach, FL
    Bugsy I - '68 Sprite w BE Bonnet - Gone but not forgotten
    Bugsy IV - '60 Bugeye - 1,275+.040 and a 5-Speed - CA Car - 2nd Owner from new - 10/12 Painting done, reassembly, cutting, and buffing in progress.

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    Great Pumpkin aeronca65t's Avatar
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    Re: DIY - Front tube shock conversion

    Peter C. has an excellent reputation. I would not hesitate to recommend him to someone who wishes to keep their car in standard configuration.

    My own brother asked me about doing the tube shock swap and I advised him to just keep his shocks properly filled with 20W for now and have them rebuilt if needed. His Midget is only used for cruise nights and to go to a MacDonalds near his house. The normal lever dampers are fine for that type of use. And probably OK for autocross too.

    The benefits of nitrogen gas-charged dampers (like the Monroes I use) is not just a matter of cost. They do not fade as quickly with severe usage. This matters if you are racing a car for longer distances. My car raced mostly endurance races (in the EMRA-series) for over 10 years. I ran a lot of 3 and 4 hour enduros and the gas-shocks maintain efficiency under that type of use.

    In the old days, people would use all sorts of concoctions try to hold back fading (like putting STP in their lever-shocks). We also messed with shock valves (I know that stiffer valves are available now). But after a few hours, the lever shocks really fade anyway.
    These days I'm only doing shorter vintage events so fading is less critical. I would guess about half the guys are running tube dampers in the front with the other half are running levers. But no one is running coil overs in front or any of the exotic SCCA Prod. setups (not allowed plus big $$$$!). We have to keep essentially the same setup .
    I would bet most are running tube dampers in the rear even in vintage.

    Bottom line: It's all about having fun with your car the way you want to. Some of us are like Lord Morris and some of us are like Cecil Kimber. Lots of room for both types.

    Nial's #909 Spridget
    My Race Events
    Spridget~MGB~Miata~Austin A35~Midget~Aeronca65T~Super 7~Accord~Chevy TowVan
    Jersey Music!

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    Re: DIY - Front tube shock conversion

    Nial, I agree with the loss of damping over a race period exceeding about 30 minutes, in my experience. We've toyed with gas charging the lever shocks, and we can do that (expensively). BUT, we have had tremendous success with Redline's synthetic suspension fluids. The vintage guys are giving very good reviews. The Redline suspension oil is very stable at high temperatures which is what is allowing the cavitation in the usual hydraulic oils.

    Peter C
    www.worldwideimportautoparts.com
    Home to many cars, and many parts.....
    If they would just meet up with each other without me having to introduce them all the time...

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    Re: DIY - Front tube shock conversion

    I have tube shocks on all four corners of my car and I LOVE the ride and handling. My conversion is inspired by Nial's but somewhat different in execution... at least on the front. My conversion requires no modifications to the car whatsoever. My rears are done almost exactly as described on Nial's web page. I invested a lot of time developing my conversion with the idea that one day I would sell it as a kit. In the end, I spent way more than buying a set of rebuilt shocks from Peter C... and ended up with a kit that could not compete with PeterC's pricing. If I did it all over again, I would buy the rebuilt shocks, but I do really love the ride/handling of my care, and I am super proud of my engineering.

    While contemporary cars are built to very exacting engineering specifications... Spridgets were not. They were literally originally assembled from spare parts lying around the factory. Shock valving was engineered by sticking something in the car, taking it on the track and revising based on driver experience. Bolting something on the car, taking it for a spin and seeing how you like it is totally consistent with the engineering practices used to develop the car.

    But if economy is your primary concern and you are not afflicted by an illness that compels you to do things that people tell you can't/shouldn't be done, your best bet is to buy rebuilts from PeterC.
    You can live in a car but you can't drive a house.

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    Re: DIY - Front tube shock conversion

    Quote Originally Posted by Morris View Post
    I have tube shocks on all four corners of my car and I LOVE the ride and handling. My conversion is inspired by Nial's but somewhat different in execution... at least on the front. My conversion requires no modifications to the car whatsoever. My rears are done almost exactly as described on Nial's web page. I invested a lot of time developing my conversion with the idea that one day I would sell it as a kit. In the end, I spent way more than buying a set of rebuilt shocks from Peter C... and ended up with a kit that could not compete with PeterC's pricing. If I did it all over again, I would buy the rebuilt shocks, but I do really love the ride/handling of my care, and I am super proud of my engineering.

    While contemporary cars are built to very exacting engineering specifications... Spridgets were not. They were literally originally assembled from spare parts lying around the factory. Shock valving was engineered by sticking something in the car, taking it on the track and revising based on driver experience. Bolting something on the car, taking it for a spin and seeing how you like it is totally consistent with the engineering practices used to develop the car.

    But if economy is your primary concern and you are not afflicted by an illness that compels you to do things that people tell you can't/shouldn't be done, your best bet is to buy rebuilts from PeterC.

    Morris, I found some posts about your old design....What made it so expensive? I looked like everything was made out of aluminum bar? Also, I loved your coil on plug stuff, are you still running that?
    David Doan - Frisco, TX
    david at doan.us
    http://doan.us/blog/bugeye/

    1959 Bugeye - AN5L-26655

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    Yoda Morris's Avatar
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    Re: DIY - Front tube shock conversion

    To answer your question accurately, I would have to dig out a spread sheet that I think is now lost thanks to a hard drive crash. From the fuzzy banks of my memory... the cost of the materiels (buying in small batches) was roughly what I hoped to sell the kit for. I had it in my head that the kit had to be a certain percentage less than a pair of rebuilt shocks to compete... especially since a significant number of would-be installers are going to have to shell out for a rebuilt pair of shocks due to shaft play. Add to the expense of raw materials a build time of several hours per kit (of course that could come down with investing in better tools and developing better procedures and jigs). For a diy builder, the kit could be rather affordable if he had access to all the tools required.

    I keep meaning to collect what remains of my notes and assemble a web page with instructions on how to build the kit... but I have a long todo list.

    As for the COPS. I am still running that and LOVE it. It really wakes the car up. A friend of mine drove the car the other day and asked me if it was turboed.
    You can live in a car but you can't drive a house.

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