Alignment and tires for Birkin

[pethier]

I have a 4:00 appointment tomorrow with thealignmentguy.com to swap tires and set the front alignment on my Birkin. Lucky me that there was a cancelation. He was all booked up in the week before our first double-autocross weekend. 

 

I assume that a live-axle Birkin has no rear-alignment adjustability. 

 

The front camber is adjustable via a system I have not come across before.  I intend to shoot for the same area as my non-adjustable Caterham has.

 

The tires I am going to put on are takeoff Yoko A052 205-15 from a friend who is a national champion.  I was a bit disappointed that the bolt circles on the Caterham and Birklin are different.  The wheels on this Birkin are 7x15.

 

Well, I'm off to measure the camber on the Caterham.

[pethier]

In my shop, getting a perfect reading on each camber is iffy.  Since the front camber on the Caterham is not adjustable anyway, I figured i could just check the total negative camber for both sides and divide by two.  I zeroed the electronic gizmo that measures angles on the RF wheel.  Then I brought the gizmo to the other side and read the difference.  Bang on 5 degrees.  Therefore, I surmised that Caterham were probably shooting for 2.5 degrees of negative camber.

 

Got the front of the Birkin set to 2.5 degrees negative camber and zero toe.  The caster is not adjustable, and measures 8 degrees.  Dogtracking does not appear to be a problem:  The thrust angle is -0.02 degrees.

 

I'm not ready to buy new tires for these 7" wheels.  I have 8" wheels for the Caterham, which will be a faster car when it's finished.  I got the secondhand Yoko A052 205-15 tires mounted.  These don't seem to have any flange-side voids, unlike the Prisoner wheels and the 8" wheels I have for the Caterham.

 

If the weather cooperates, I'll take it around the cones this weekend.  It appears that I can adjust the front swaybar without crawling on my belly like a reptile.  

Edited April 23 by pethier

[pethier]

Well, it's autocross eve.

 

It will be a bit chilly tomorrow.  A little warmer on Sunday.  

 

For reasons I don't understand, there were 1/4-inch spacers under the back wheels.  I took them out.

 

There were no spacers at the front. The hub on these wheels just clears the front caliper.  The studs in front would not be long enough for spacers.

 

So it goes.  You buy a Birkin that has who knows how many owners, you find stuff.

[11Budlite]

8 hours ago, pethier said:

For reasons I don't understand, there were 1/4-inch spacers under the back wheels.  I took them out.

 

There were no spacers at the front. The hub on these wheels just clears the front caliper.  The studs in front would not be long enough for spacers.

 

IIRC the Birkin recommended offset was different than the typical Miata-based wheels that most people used when they upgraded from the stock wheels. The stock wheels on my old Birkin were quite a bit heavier than the RPF1's that I replaced them with. I remember several Birkins that used the same Kosei wheels that you have on your car. If you have the 38mm version of the Kosei it could be that they added the 1/4" spacers to get the offset closer to the Birkin stock recommendation. I think stock was around 30mm but it's been a long time since I played with Birkin wheels so I could be mistaken.

[pethier]

14 hours ago, 11Budlite said:

 

IIRC the Birkin recommended offset was different than the typical Miata-based wheels that most people used when they upgraded from the stock wheels. The stock wheels on my old Birkin were quite a bit heavier than the RPF1's that I replaced them with. I remember several Birkins that used the same Kosei wheels that you have on your car. If you have the 38mm version of the Kosei it could be that they added the 1/4" spacers to get the offset closer to the Birkin stock recommendation. I think stock was around 30mm but it's been a long time since I played with Birkin wheels so I could be mistaken.

The weird part here is that 1/4-inch for roll radius on the front would have a heck of a lot more significance than on a solid back axle.

Edited April 26 by pethier

[pethier]

It rained Saturday morning.  I took the Cayman, still on its all-weather tires.

 

Hope runs high for a drier Sunday.  

[pethier]

Did get a drier Sunday.  Raining when we arrived at the site.  Managed to wait out the rain and get annual tech inspection on the Birkin.  Then I put the car in the trailer in cse it rained while I walked the course.

 

Not raining  when it was time for my first 3-run heat.  I was not getting traction on the dodgy surface of Canterbury Park's overflow lot.  Ever since they sealcoated this lot, it releases aggregate we call "Canterberries".  These tires may wake up with a better surface and warmer temps.  When I went to start the engine for the third run, I needed a push start.  Cranking slow.  After the run, I found a place on the paddock lot higher than my rig.  Turned off the engine to see if it would restart.  Nope.  Pushed it down the hill to my rig.  Removed the air filters.  Removed the hood.  Fired up the F-150 and hooked up the jumper cables. After a while, I was able to start the Birkin.  Let the big Ford charge the little Ford for a while.  Turned off the Birkin, disconnected the cables and tried to start it again.  No go.

 

Hooked up and let the big Ford charge the little Ford again.

 

As time approached for my three runs in the afternoon,  I started the Birkin, refitted the hood, reinstalled the air filters, and drove the Birkin to its spot in grid.  

DIdn't turn off the car until I had completed my runs and driven the car behind my trailer.  Winched it in and tied it down.

 

I carried passengers all day.  My best was 39.859.

FTD was 33.405.

Not exactly great.  Still was fun.

Now I will have to figure out whether the battery is toast or the alternator circuit is not working.  My money is on the battery.  

Edited April 26 by pethier

[pethier]

Raining pitchforks and hammer handles today.  Rainy days and Mondays.  Well at least it IS Monday and nobody was planning on autocrossing around the Twin Cities.

 

Probably tomorrow I will look into replacing that battery in the Birkin.  The easiest way would be to get the same size battery.  Would have to be an AGM to mount it the same way, as it is lying down in there.

[pethier]

The goofiness with the Birkin turned out to be the starter itself.  With all the times it was installed, uninstalled, and bounced around in the shop, it now seems to be functioning perfectly.  It started as many times as you would expect at the autocross novice school on Saturday and at the 7-run regular autocross on Sunday. 

 

 

Now I am putting the Birkin up for sale and I have to show some actual performance for the autocross crowd.  Put 4 new Yoko A052 205-15 on it yesterday.

 

[m2711c]

How much are ya planning on asking for it?

[pethier]

2 minutes ago, m2711c said:

How much are ya planning on asking for it?

This is a decent car.  I'm only selling it because a  CSR has taken over its storage space.  I can't sell 74PHIL because it is a work in progress.

 

I have about 20 grand in the green Birkin.  I'm strapped for storage space and willing to take a beating.  I'd take 15 grand, FOB Saint Paul Minnesota.

 

Spares include:

 

Two cycle fenders in the same green paint.  No brackets for these fenders.

 

Factory bolt-on-style spare-tire-carrier which needs repair.

 

Spare tire on a wheel which does not match the K-1 Racing 7x15 wheels on the car.

 

Full top which I have stretched to mostly fit.  Birkin uses a single "hood stick" which pulls apart for storage.

 

Doors which appear to be correct for the car.  I don't think they have been used because interior snaps have never been installed in the interior.

 

Full tonneau assembly which consists of the attached boot cover and two separate cockpit pieces.  These do not need to be stretched, but a zipper or two need some fettling.  I'd call it ready for sun protection but not for rain protection.  There are no headrest pockets: The headrests easily pull out.  The car has that vintage look when covered in the tonneau.

 

Car runs and drives.  I intend to run it with the new tires in an autocross this Sunday.

 

The new side mirrors are perfect.  It has a fresh alignment.  All five forward gears and reverse work.  The Zetec engine has a RaceLine water rail and the sort of throttle bodies one would expect to replace side-draft Weber carbs (not the Hayabusa setup now in 74PHIL).  Four-wheel disk brakes.  I have not tested is for LSD, but the few autocrosses I have run on not-sticky tires makes me think it has something.  The front swaybar is adjustable.  The coilover units have adjustable perches so you can set the ride height and corner-balance the car.

 

I'll put together a proper ad with lots of pictures REAL SOON NOW.  Right now, I need to finish putting a temporary passenger seat in the CSR.

 

I'd deliver the car within a short distance for free. Price for distant delivery is something I'd need to determine after crunching the numbers from my recent California trip.  Otherwise, the buyer would need to arrange transportation.

 

Would I be afraid to drive it a long distance?  I trust the car, but I don't trust the weather.  The top is not completely ready, and the interior snaps are not there for the doors.