Pedal shaft and pedals worn

[alaric]

Hi all.

I've got my pedal box out of my '72 +2 again, and am trying to sort out why the throttle pedal was binding against the brake pedal. The pedal shaft looks quite worn to me, and the collar that the throttle pedal is welded to looks quite worn also.

I presume that when these components are up to scratch the throttle pedal has little sideways movement, and there's clearance between the throttle pedal and brake pedal.

Has anyone come up with a neat mod using roller bearings or suchlike, or replaced the shaft, or bushed the collars on the pedals?

Suggestions would be appreciated.

Thanks.

Sean.

[gerrym]

Sean, I posted a reply on this (see Oct 2nd 2008) in the Plus 2 Forum.

You can PM me if you need any more details.

Regards

Gerry

[alaric]

That's just the ticket Gerry. I was hunting for bushes on the web last night so your reply has asnswered my question admirably. Can you remember which bushes you fitted - by flanged I think you mean that there's effectively an integral washer at the end - I would think of it as a top hat profile.

I've no idea what tolerance works - presumably you buy the 12mm bar, and choose the bushes to fit that and the reamed out pedal shafts less the tolerance. I have to say that I was a little concerned at reaming out the pedals as it's removing material from a safety critcal part of the car. Are the bushes a tight fit onto the bar - presumably they don't need to be really tight.

Anyway, I'll take a look at the website and see if I can sort out a set of components.

All the best.

Sean.

[gerrym]

Sean, top hat or flanged, yes we are talking about the same.

For the shaft, I used 316 Stainless. Millstock Stainless supply precision ground shafts, in a variety of material grades. I chose them because they were happy to sell me a short length.

For hole fit tolerances, the Igus bushes are designed to provide an E10 hole if fitted correctly to a reamed H7 hole (complete with 30 degree lead in taper. Millstock can provide shafts in h9 tolerance, h8, h7 in the sizes you will need.

Regarding loss of strength, I suspect that deflection is the limiting criteria rather than strength. However, if you wish to increase the strength of the shaft beyond what Lotus provided, Millstock can provide a shaft in Duplex F51. Beefing up the end supports in the pedal box carcass will also help. Other than that, the increase in the pedal shaft holes to 14mm and decrease in shaft size to 12mm is something you will need to be happy with. (Obviously, your current situation with brake-accelerator interference is safety critical and also a MOT failure)

Regards
Gerry

[alaric]

I was just looking for a shaft - stainless is the way to go.

I'm thinking of needle rollers at the moment:

http://simplybearings.co.uk/shop/p8213/ ... _info.html

6 of these, which are each 10mm internal diameter, 14mm external diameter and 10mm length, should support the pedals admirably. If I bore out the pedals to 14mm they should press in; I should probably put a loose collar between the rollers on the clutch and brake. I then need shims between the pedals as in the current set up, and need some bushes to accomodate the 10mm shaft in the 13mm holes in the pedal box. I found some 5mm long top hat bushes, which I could push in from the inside of the pedal box if the endfloat on the pedals allows - the flange thickness is 1mm but I could mill down the pedal shafts slightly to make it all fit. I'll try and draw it up and see if it all stacks up.

Otherwise the bushes look ideal for the job.

Sean.

[alaric]

Hi all.

I've got a stainless 12mm (typo corrected - thanks Gerry) shaft on its way, and have just ordered the Igus Iglidur G bushes following Gerry's approach. I've gone for 2 off GFM-1214-24 for the brake pedal, 3 off GSM-1214-25 for the throttle pedal and clutch pedal, and 2 off GFM-1214-03 for the ends of the shaft where they go through the walls of the pedal box. So I should just need to bore out the pedals and box to 14mm, push in the bushes, sort out the endfloat and fit some clevis pins.

Hope it works out.

Sean.

[gerrym]

Sean, maybe I'm spotting the obvious mistake, but I believe you need (are ordering) a 12mm nominal shaft.
Regards
Gerry

[alaric]

Well spotted Gerry - I've corrected the error - that's what happens when you're multi-tasking at work...

All the best.

Sean.

[jono]

Just going through this with my pedal box. I really like those Iglidur bushes which have worked a treat on my mountain bike rear shock pivots however my engineer friend doing the work is a bit old fashioned and has insisted on making the bushes from oilite bar

[john.p.clegg]

Sorry to but in but instead of bar,why not use tube,with an adequate wall thickness it would be lighter and just as strong,small feed holes drilled in the required places and a grease nipple fitted ot one end,blanking off the other end?

John

[alaric]

You could use a tube, but I think a tube of the same diameter is not going to be as strong. My understanding is that for a solid bar the second moment of inertia is proportional to the radius to the power of 4. In the case of a tube it's proportional to the difference between the external radius to the power of 4 and the internal radius to the power of 4.

According to that, you're right, due to the 4th power dependence there would a non linear loss of flexural rigidity through use of a tube - as long as you choose the wall thickness correctly you should be ok.

However, given the brake pedal is hanging off this bar, I reckon the best way of saving such as small amount of weight is for me to go on a diet.

One area where I would be keen to reduce the car's weight is in the doors. They're really heavy once full of all that metal, glass and electric motor etc.

All the best.

Sean.

[john.p.clegg]

Sean
I'm not primarily after loosing weight,that is secondary,the main reason being that you are able to grease the pedal shaft with ease..

John

P.S. Did it years ago...works well.

[LotusEngineeringBuff]

Hello Everybody,
I just thought I'd share with you a couple of pictures of a pedal box I am rebuilding. I do it for a future RHD to LHD conversion, so I have all my time. In top of that I have access to machine tools and the welding is done by one of my company's mechanics.

1) I picked a 12mm precision SS shaft onto which I pressed and welded an end-ring
2) I drilled oversize holes in the box, machined steel bearings with higher precision and larger area than the original ones. I had my bearings welded on the box and I in-line reamed them to size after they were in place.
3) I drilled oversize holes in the pedals, made bronze bushings to the correct diameter and pressed them in the bores. Then I reamed them to fit tightly on the shaft
4) I machined a square hole on the top of the box to access the pins on the top of brake and clutch pedals. Then, I made a stainless steel cover attached with 12 M4 screws since I consider that the top of the box of a structural (i.e. load carrying) part of it.

I post a few pictures before everything is powder coated and you do not see anything.

After that, what still needs to be done is finishing the shaft (clevis pin), and re-shaping the pedals, because they are for a RHD and I will have to bend them "the other way" for my application. I'll do that when I actually start the conversion because I do have to have the box in place to see exactly what shape they need to be.

Regards
Fran?ois