Accelerator Pedal Modification

[Paul_D]

After my post here and on Instagram, I've had a couple of people ask me if I'd mind providing a slightly more detailed write up of my accelerator pedal modification.

 

I've struggled to get to grips with heel and toe in the Exige since buying it, more so than in cars I've had previously. After spending a bit of time experimenting I came to the conclusion that at least part of the problem was the position of the accelerator pedal relative to the brake. The distance away wasn't too bad (although it could be closer), but the fact that the accelerator pedal sat lower down even when hard on the brakes meant I had to twist my foot a bit more awkwardly than I'd like. (Especially as the Exige seems to need a decent 'stab' to get the revs up)

So the objective was to have a pedal which I could adjust until I found the optimum position for me to use.

Here's what I did. (Also, if you happen to be friends with a 3 foot tall contortionist, now would be a great time to tell them how much you love them and ask if they fancy popping round for a beer...)

First stage was pedal selection. It needs to be at least as big as the original, and ideally also curved to match the pedal mount. After a bit of Googling I settled on "Grayston Competition Pedal Pads Plates Extensions - Silver Anodised Race & Rally" These are available from eBay and a few other places. I only want the accelerator, but at £16 I'm not too sad about wasting the other pedals. (And you could fit them too so they all match if you wanted)

 

Next step is removing the original pedal. This is secured in two ways. Rivets and Glue. Here's a picture from behind and from the front:

Using a suitable drill bit (3.2mm is perfect) drill out the rivets. Now the pedal is just held on by the glue. I'm sure it's possible to just pull the pedal really hard, but it's hard to support the mounting arm and I didn't want to risk breaking anything. I got a heat gun and blasted the pedal in the area between the two rivet holes for a while. This softens up the glue. I put a towel behind the pedal to protect the carpet from potentially getting burned. I then used a set of pipe pliers to peel the pedal off, which still took a decent amount of force.

This is what you should be presented with:

 

I used a plastic scraper to remove the glue residue, otherwise you'll see it through the new pedal.

You now need to decide on where you want the new pedal in terms of left-right placement. If you want to end up with the pedal 8mm closer to the brake the drill your holes in the centre. If you'd rather keep the distance the same and only want to change the height then drill your holes 8mm to the right of centre. I chose to have the pedal closer to the brake. I confirmed this would be ok by temporarily sticking it in place with a double sided sticky pad and making sure I could still press the brake without accidentally clipping the accelerator.  

Next it's time to drill the new mounting holes. I put a piece of masking tape on the pedal so I could draw on it easily. There were two things to consider when finalising the position of the pedal in terms of mounting holes - 1) not too close to the edges, and 2) needing to avoid the arm that the mounting plate is welded to. This is where my holes ended up:

You can see that the bottom hole ended up just overlapping the original rivet hole. This is actually a good reference for anybody else doing it. 
Drilling tips: Pack a load of wood behind the pedal to stop it moving. You'll want to use a drill bit in the 5.2 - 5.5mm range. 

I made a slight mistake and ended up marginally to the left of centre. This made doing the top nut / bolt up difficult as it was close to the arm. Try to stay centre or fractional to the right of centre if you can. 

The fixings I used are M5 Countersunk hex machine screws like this: https://www.amazon.co.uk/35mm-Socket-Countersunk-Machine-Screw/dp/B07MJQKQZ5/ref=pd_lpo_3?pd_rd_i=B07MJQKQZ5&psc=1

I used M5 Nyloc nuts with them, and small M5 washers. 

Here's where the bolts should be coming through after your drilling:

If you just wanted the wider pedal and were happy with the original pedal height, then you could put the washers and nuts on now, tighten it up and you're finished.

If like me you want to raise the height, now is the time to fit your spacers between the pedal and the mounting plate. I found the easiest solution for me in terms of spacers was some M6 nuts I had handy. They slide nicely over the bolts without wobbling around. I used two of them to raise the pedal by about 11 or 12mm I think. 

Note that the amount of screw protruding at the back is not a problem. The pedal hits its stop before it gets the floor. Having the extra length allows you to fit additional spacers if you so require.  Your pedal is now fully height adjustable (Well, in terms of making it higher than standard)

The final stage is to find the number of a local chiropractor to sort your back and neck out after being contorted inside a stupid little car for an hour. (Or perhaps I'm just getting old...)

[Jcx]

Brilliant! I wish you lived closer… 🤗

[snowrx]

A threaded M5 does not have much strength to resist lateral bending forces from your foot on the edge of the pedal. Once you find the height you like, I'd strongly suggest you add a spacer that spans the width of the pedal arm pad to keep that load off the fastener.

[Paul_D]

I think it’s fine as it is. There’s virtually no resistance on the accelerator pedal so the bending forces are very very small.

I was originally planning to fabricate a wider spacer but after the test fitting didn’t feel the need. 

[tactical lizard]

Interesting mod for the taller driver and something I may look into, My biggest issue is that I can't twist my foot so I'm braking with my big toe and blipping the throttle with my little pinky toe!

How much wider is that new pedal compared to the standard one?

[Paul_D]

That was my issue really. The accelerator being lower meant I was trying to twist my foot to an awkward angle, my knee was against the steering wheel and so on.

I'm not sure on total width, but mounting it centrally like I have brings the edge of the pedal about 8mm closer to the brake than the original pedal. Combined with the accelerator height now being level with the brake, it means my foot doesn't have to twist much at all to give a decent blip. 

If you did decide you wanted to bring it even closer, you could mount it using the right hand set of holes in the pedal rather than the central holes. If you were doing that then I'd use a wider spacer to support the pedal a bit more to the left.

Just following up on snowrx's comment above, the M5 fixing is not seeing much force. The M6 spacer nuts are free to move, and the pedal is clamped tight to them and the mounting pad. Therefore the force is still being transferred through the spacers to the moving arm. It's not bending the M5 screw. The accelerator pedal needs about 1 - 1.5kg of force to move. The fixing arrangement I've used would take many times that, and the lack of support on the left side of the pedal just means that the new pedal would physically distort before the fixing method failed. As you can imagine that needs far more force than you'd ever apply to the accelerator. 

[Exx]

On 07/11/2021 at 12:42, Paul_D said:

I then used a set of pipe pliers to peel the pedal off

Any tips for that part ? Why did u need a set and not only one ?

[Paul_D]

Sorry, was just lazy terminology. I mean a single pair of pipe pliers. 
 

Just google Pipe Pliers. Any standard sized pair should fit fine. 🙂

[Exx]

I have ordered a 300/500° Bosch heat gun

Yes you mean a standard pipe plier like this ? https://www.amazon.co.uk/Gunpla-Groove-Adjustable-Multi-Grips-Spanners/dp/B07CYYP41M/

 

I habe DBW pedals to mount

[Paul_D]

Yep, they should be perfect. You’ll be able to get a good grip of the pedals. 

[Exx]

Did you damage the OEM pedals when you removed them ?

[Paul_D]

Nope, no damage. I can put everything back to standard again if I wanted.