wheel drive pins - 3 in front, 6 in rear?

[mikey]

Hi all, hope everyone is surviving quarantine. I spent a bit of time in the garage today with the Lola T91-50 F3000. I'm curious, regarding wheel drive pins. My rear wheels have 6 drive pins each while the fronts only have 3 each. These are 13" dia x 15" wide rear and 13" dia x 10.5" wide front. Is 3 pins really enough under heavy braking stresses? A front wheel is pictured - it looks like it had additional pins at one time.

[RussMcB]

I think I've seen similar on FA cars.

[pakracer]

Most Indy cars are the same way fewer drive pins in the front than the rear. Mainly due to the forces of driving the rear wheels. The drive pins may have been changed in the wheel at one time.

[Magic Motorsport]

You are going to be tightening the hub nuts to 400 lbs/ft which helps a little! Piece of advice. Always slacken off the nuts when you come in from a session, when cooled you will find it extremely difficult or at my advanced years impossible.

[Jamesbe]

400? Wholly hell.

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[Magic Motorsport]

400? Wholly hell.

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Now I check my Reynard 93 manual which is the similar size to Lola it actually recommends 450 lbs/ft.

[J Leonard]

Aren't these specs for the spindle nuts not the wheel retainer nuts?

[mikey]

You are going to be tightening the hub nuts to 400 lbs/ft which helps a little! Piece of advice. Always slacken off the nuts when you come in from a session, when cooled you will find it extremely difficult or at my advanced years impossible.

thanks for the tip! and yes it is 450 ft-lbs. for the wheel nut, as I understand it. Bought a very large (3' long) torque wrench that cost of bunch of money to ensure it is right! Hadn't thought about loosening while hot - makes sense.

But bottom line, you're saying that because of the wheel nut torque the drive pins aren't as stressed and 3 would be ok for the front?

[Roland V. Johnson]

The front wheels only have brake and corning loads going through them The rears also have engine drive loads.

[mikey]

The front wheels only have brake and corning loads going through them The rears also have engine drive loads.

I understand this, however this car is capable of 2.5-3.0G braking and cornering. My Pro Formula Mazda was a much less capable car and still had 4 drive pins on the front, so I thought I'd check.

[Magic Motorsport]

I understand this, however this car is capable of 2.5-3.0G braking and cornering. My Pro Formula Mazda was a much less capable car and still had 4 drive pins on the front, so I thought I'd check.

Survey of cars in our workshop.

F3. Dallara F397, Dallara F398, Dallara F302, all small spindle, 115 lbs/ft, 4 drive pins all round.

F2. Toleman TG280, Toleman TG280, both small spindle, 115 lbs/ft, 4 drive pins rear, 3 drive pins front.

F3000. Reynard 94D. Large hub, 450 lbs/ft, 6 drive pins all round.

F1. Shadow DN9B. Large hub, 450 lbs/ft, 4 drive pins all round.

[mikey]

Survey of cars in our workshop.

F3. Dallara F397, Dallara F398, Dallara F302, all small spindle, 115 lbs/ft, 4 drive pins all round.

F2. Toleman TG280, Toleman TG280, both small spindle, 115 lbs/ft, 4 drive pins rear, 3 drive pins front.

F3000. Reynard 94D. Large hub, 450 lbs/ft, 6 drive pins all round.

F1. Shadow DN9B. Large hub, 450 lbs/ft, 4 drive pins all round.

Well that clears it all up LOL!

Derek did confirm he only ran with 3 in the front and by all counts I hear he was fast so I guess I can stop worrying about it or buy 3 more pins per wheel and install them. where can I even get them?

[Lee Johnson]

Magic --

Another key factor to the clamping force is the thread pitch of the nut/spindle. It would be interesting to know what those are for the different cars in your shop. {I bet the "small spindle" ones have finer thread pitch ==> more clamping force per ft-lb of torque with same friction "losses".}

Lee
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Survey of cars in our workshop.

F3. Dallara F397, Dallara F398, Dallara F302, all small spindle, 115 lbs/ft, 4 drive pins all round.

F2. Toleman TG280, Toleman TG280, both small spindle, 115 lbs/ft, 4 drive pins rear, 3 drive pins front.

F3000. Reynard 94D. Large hub, 450 lbs/ft, 6 drive pins all round.

F1. Shadow DN9B. Large hub, 450 lbs/ft, 4 drive pins all round.

[Magic Motorsport]

Magic --

Another key factor to the clamping force is the thread pitch of the nut/spindle. It would be interesting to know what those are for the different cars in your shop. {I bet the "small spindle" ones have finer thread pitch ==> more clamping force per ft-lb of torque with same friction "losses".}

Lee
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Hello Lee.

Point well made. Certainly the thread pitch of the small axles is much finer than the large ones. Right now the shop is closed and being over 70 I am in solitary confinement at home. Probably in a week I shall need to up there just to smell the 105 fuel!

Nick.

[innerloop]

Well that clears it all up LOL!

where can I even get them?

I'd also be interested in a source for new drive pins. I may need some for my GForce Indy car.

[Lee Johnson]

Hello Lee.

Point well made. Certainly the thread pitch of the small axles is much finer than the large ones. Right now the shop is closed and being over 70 I am in solitary confinement at home. Probably in a week I shall need to up there just to smell the 105 fuel!

Nick.

Hi Nick,

I understand your lock-down dilemma. I am in a similar age range, but have the benefit of the car being in my home shop.

When the fuel vapours addiction overwhelms you, perhaps you could also check some of those spindle thread pitches at your shop and post results to continue the education of your co-addicts!

Lee

[Magic Motorsport]

Hi Nick,

I understand your lock-down dilemma. I am in a similar age range, but have the benefit of the car being in my home shop.

When the fuel vapours addiction overwhelms you, perhaps you could also check some of those spindle thread pitches at your shop and post results to continue the education of your co-addicts!

Lee

Afternoon Lee,

Well I finally made a bid for freedom.

F3000 2"-12 unified, F1 2"- 8 unified, F2 3/4"-16 unified & F3 M18 1.5 metric.

Everyone take care.

Nick.

[Charles Warner]

Might as well raise the issue again. These are not designed as "drive pins" but mainly locating pins. Yes, they will stop the wheel from rotating if the wheel nut loosens. However, if the units are in proper shape, clean, and torqued properly, the wheel nuts should not loosen at all. They are designed to hold the wheel tight under all loads. If, as is often believed, these were truly drive pins, then they would be lifed and require crack checking or replacement often. I have never heard of a manufacturer (LOLA, March, Ralt, etc.) suggest any maintenance at all relative to these pins.

My March F1 cars all had 3 locating pins, front and rear, and they were small - .10mm IIRC.

As for loosening the wheel nuts immediately after coming in, there is no harm in that. However, harm is done by re-torqueing them when hot. Let them normalize and do not expect the torque needed to remove them to be the same as used to install them. If you insist on checking that realize you need a reversing torque wrench.

I do have a supply of new wheel pins.

overall length 1.375"
diameter .550"
pin height .700"
thread 3/8-24
thread length .375" with a .300" shoulder

$7.00 each shipped in the CONUS.

email fattogatto@msn.com for details

[john f]

You are going to be tightening the hub nuts to 400 lbs/ft which helps a little! Piece of advice. Always slacken off the nuts when you come in from a session, when cooled you will find it extremely difficult or at my advanced years impossible.

It has been my experience that the nuts are tighter when everything is hot, and therefore easier to loosen after cooling down. This is on my Lola T163 which uses mag wheels with steel stubs and nuts. I believe that the mag expands more than the steel as everything heats up, making it sometimes impossible to remove until things cool down. My nuts are torqued to 450 lb-ft . Just my $0.02.

john f