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Posted by: Randal Aug 9 2004, 11:49 AM

I totally blew my last two runs yesterday missing shifts.

I know part of this is the driver, but I also think the Rennshift springs are suspect.

When we first installed the Rennshift it took some getting used to, but it worked all the time. I've run 8 events now with the new shifter and it was fine for the first four, but not for the last four.

Saturday and Sunday at Alameda I was hitting reverse, shifting from first to second. Typically this was during cornering, but that is the way course work; you just can’t sit there on the rev. limiter waiting to the corner to complete.

Also during very heavy cornering (like in a slalom) shifting from second to third, it was going into fifth.

On down shifts from third to second it was hitting reverse. I destroyed a great run on Saturday on the second to the last corner....just couldn't find second. (Like Grind Me A POUND!) Very ugly.

So what are the ratings on the standard springs? Is there somewhere I send my existing springs to have them tested? What heaver springs are available?

At Alameda I was shifting up/down 8 times. Miss any shift and you blow the run.

BTW the 911 guys don't have to shift more than once.

Posted by: James Adams Aug 9 2004, 12:29 PM

Maybe you have a bad engine or trans mount. The shift pattern will move while cornering if the trans moves.

It sounds like you are fighting the shifter though, you have to let the shifter choose the gear plane and not force it side-to-side where you think it should go. Palm to push or three fingers to pull is the best technique for getting into 2nd and 3rd and not creating a side force.

You got heavier (white) springs with the shifter - if Brad didn't give them to you then let me know and I will send you a pair.

If it worked the first 4 runs and not the last 4, maybe a bushing broke.

Posted by: Brad Roberts Aug 9 2004, 02:10 PM

He was sold his shifter prior to us deciding that stiffer springs should be available. He has solid tranny mounts and new front mounts. I spent 30+ minutes going over EVERYTHING. Trust me.. I didnt want it to be the shifter. Just me grabbing the stick and moving it side to side... WAY to easy. Easier than a stocker at this point.

I just gave Randal the stiffer spring kit (now I'm short one)

B

Posted by: James Adams Aug 9 2004, 02:33 PM

It's funny - people are SO different when it comes to the springs. Some people want really stiff springs, some love the normal setup, and some have a real hard time getting used to the (extra) springs at all.

FYI, the standard springs are always lighter than a stock shifter.

Posted by: Randal Aug 9 2004, 03:15 PM

Please come take a ride with me in an autox venue; you’ll find the lateral forces somewhat more powerful/heavy than what would be considered "normal."

Secondly, the springs worked fine for the first 4 events (8 or 10 runs per event), but then started to go off.

As Brad said everything on the car is solid as it was just in the shop being checked.

It could be that my new slicks (Hoosiers) were really hooking up (they were) thereby creating more cornering force and in turn a heaver hand by the driver. However, I discount this as I’m strapped in very tight in a Kirky seat that keeps you in one place..

BTW what is the spring rating on the old/ new springs? Seems like a big difference just compressing the old one, by hand, vs. the new, which is hardly compressible.

Should I be putting the little inter spring back in with the new ones I just got from Brad?

Posted by: Randal Aug 9 2004, 03:24 PM

Forgot to mention that I drove the car around Los Altos today just to see how the shfter worked in "normal" conditions.

It didn't miss a beat, nice and smooth and engaged perfectly.

Posted by: James Adams Aug 9 2004, 04:12 PM

What I think does not matter. I have customers with big-track cars that like the light springs, and grocery-getter types that prefer the heavy springs.

The side load at the knob is 7lbs for the standard springs and 12lbs for the heavy springs. Stock shifter is 10-11lbs with good components.

Do not use the inner spring with the white spring.

Posted by: Randal Aug 9 2004, 05:55 PM

Thanks for the response.

How do you measure the 7 or 12 lb side load; from what point on the shifter.

Am I correct the shifter would be in neutral?

Posted by: James Adams Aug 9 2004, 06:14 PM

That is measured at the top of the stick where your hand would be. In neutral, just as the stick moves.

The white springs are a big increase over the standard springs in feel. I think you will be satisfied with them. If not, let me know, and we can work the issue further.

Posted by: Brad Roberts Aug 9 2004, 06:28 PM

James.. just to let you know.. I always blame the driver...LOL

Your big track guy's have nothing on a fully prepared AutoX car. They do not have very fast 1.4G corners every 30-40 feet. The G's they experience are gradual and nowhere near as violent as what Randal can experience in his car on slicks.


B

Posted by: James Adams Aug 9 2004, 07:05 PM

I was not trying to belittle Randal in the least! My point was to show the range of preferences that I have received feedback about - I had two specific examples I was thinking of - not "making it up so it sounded good."

Big track guys can usually avoid shifting in a corner, too, as Randal is forced to do.

Posted by: Brad Roberts Aug 9 2004, 07:19 PM

Not taken that way.. just letting you know that it is two different venues.

We have another event very soon.. we will know quickly.


B

Posted by: Van914 Aug 10 2004, 08:30 AM

James,
Why not use the inner springs with the white springs?

Posted by: James Adams Aug 10 2004, 08:38 AM

They add no measurable resistance since the white springs are so much stiffer, and they are too tight a fit inside the white springs.

Posted by: jfort Aug 10 2004, 09:50 AM

for what it's worth, i like the stiffer springs

Posted by: Eric_Shea Aug 10 2004, 10:04 AM

Hi Jeff... Eric Shea, glad to meet you

(inside joke)

P.S. I wanted to ride in your car...

Posted by: jfort Aug 10 2004, 11:35 AM

nice meeting you, too, eric. i learned a lot watching you grade 914-6's. drive east for the sean's fall run near indy.

Posted by: Randal Aug 10 2004, 11:49 AM

Measurement:

Went out last night and purchased a fish scale. Maybe not the most scientific of instruments, but a measurement none the less.

Measured the side to side load, which ended up being 6 lbs left to right, 7 lbs and a bit, right to left. So the springs, being the softer ones, are in specification.

I'll change to the new heaver springs tonight and try them out at the Marina in two weeks.

So the only explaination that I can come up with, pertaining to why they worked at first and then not later, is the G force experienced on the different courses.

No question the couse last weekend had higher G forces.

Guess that will have to do for now until we drive again.

Posted by: James Adams Aug 10 2004, 12:03 PM

Thanks for verifying that measurement on your shifter.

I think you will find the new springs to offer quite a change.

Keep me informed!

Posted by: synthesisdv Aug 10 2004, 12:22 PM

why don't you try some of james' nylon or solid motor mounts?

if you are using the stock ones, could make a big difference with shifting under a corner load.

dr

Posted by: J P Stein Aug 10 2004, 12:24 PM

Our AX this last Sunday had a curving 3rd gear blast that really got ones attention .....the car would really move around on that rough surface.... followed by a square corner that required all the brakes and a downshift to second. While thrashing my car, old Chuck made his best attempt to get it into reverse (down shifting/braking at turn in to kick the back end around....ones plate is full )......I could hear the grind from 200 yards away.........AAAUUUGGHH.

Oh well he was fast.

Posted by: Randal Aug 10 2004, 03:20 PM

Gottem (SMM)!

All the potentially movable parts are either solid, new or recently rebuilt. Brad can verify.

I'll bet the issue is corning loads, which we've essentially been increasing as we've modified the car during the last 4 events.

During the time of the last 4 event we've added adjustable high performace Koni's in the back, a Smart Racing Product ASW in the front, 250# springs in the back and new sticky slicks.

And of course as the car handles better - it is being driven faster with increased cornering load.

I'm putting in the new 12lb. RennShift springs tonight. If they don't keep me straight, then we'll figure out what is next with RennShift.

Hey, anyone out there got 24lb springs?

Posted by: Jeroen Aug 10 2004, 06:45 PM

I most think it's most likely the driver and nothing mechanical
When you're shifting under heavy side loads, your shifting movement will be off because the sideloading will make your body move, so you're basically pushing or pulling the shiftlever sideways (you may not even be aware of it)

Hopefully the stiffer springs in the rennshift will solve it.
You could also try moving your seat a little more forward or upright

cheers,

Jeroen

Posted by: Brad Roberts Aug 10 2004, 06:50 PM

Randal is 6'1 200+ lbs.. we dont have much room to move his seat. I told him the same thing... I figured his arm weight is helping to move the shifter when he has to shift in the middle of a corner. He has also had issues nicking reverse when making the 1-2 upshift with one hand on the wheel and one on the shifter.

Something I will do before the next event is install a modified shift rod. His rod going through the rear shift console bushing is loose (even though it has a new bushing with a thinner inside diameter hole) We are losing side to side motion in that bushing. The front to back motion is not affected.


B

Posted by: Randal Aug 10 2004, 07:00 PM

Guess it had to happen sooner or later.

Posted by: Brad Roberts Aug 10 2004, 07:05 PM

I want to weld one up and machine it down so it fits that shift console bushing perfectly. The ideal situation would be to run a heim joint there and let the rod slide through it. This would give us PRECISE shift rod action.

The other way to do it... something I have never posted...

Extend the shift rod to another bushing in line with the one in the stock location. This would support the shaft in two area's instead of one. Hard to describe, but it would require tig welding a piece from a old broken shift console to your new one and extending the shift rod through a second bushing.


B

Posted by: drew365 Aug 10 2004, 08:29 PM

I have one spot at Willow Springs small track that I have to shift under heavy side load from 2nd to 3rd and the trans either will crunch or not engage. I'm certain that it's caused by flexing on my tub. I plan on connecting my roll cage to the rear shock towers and possibly the shock towers to the top of the tranny mounts, in the near future. If that doesn't work I may fire the driver.

Posted by: Randal Aug 10 2004, 08:56 PM

Brad.

So this sounds like you need the car? Marina is coming up soon, so tell me the date.

BTW will this eliminate the lack of engagement feeling that happens when you engage 2nd standing still? Ugh, does that make sense?

Posted by: Randal Aug 12 2004, 09:20 AM

Progress!

The new 8" steel shifter rod is being machined as we speak.

It will be machined to fit tight in the bushing. We will alter the bushing a bit, so it slides, when we get ready to weld the rod on to the rest of the shifting rod/ lever, fork or whatever that call it.

Posted by: maf914 Aug 12 2004, 11:21 AM

I purchased a bronze bushing (the type held by a c-clip) from the bird and found that the inside diameter was about the same as the stock plastic bushing and the shift rod still had plenty of loose play. Like the plastic bushing the inner diameter of the bronze busing appears to be tapered, i.e. the inner diameter is larger at one end than the other.

I went to a local hobby shop and bought a piece of brass tubing that fit smoothly over the machined end of the shift rod where it rides in the busing. This was to be used to sleeve the bushing down to match the shift rod. I took the brass bushing and tinned the inner surface with solder. I cut a piece of the brass tubing the same length as the bushing and placed it inside the bushing. It was almost a perfect interference fit. I cleaned both pieces, added flux, hit it with the propane torch, added a bit of solder, polished it up and now have a bushing that is a fairly snug fit. The bad news is it is not yet installed, but I hope it works well. I'm concerned about possible binding though. Just in case I have a new plastic bushing standing by.

After doing this, it occurred to me that the shift rod itself could be sleeved with either a brass or other metal tube to achieve the same thing, a rod and bushing combination that fit with less play. This sleeve could be epoxied onto the shift rod which means it could be ground off if necessary. Then either the plastic or bronze bushing could be used with a snug fit.

Posted by: Randal Aug 12 2004, 11:24 AM

I'm using solid motor mounts and nylon bushings.

What we're doing now:

Changing to the 12lb springs.

Building a new shift rod end, that will be very tight to the nylon bushing.

Posted by: Dave_Darling Aug 12 2004, 06:37 PM

I've seen pics of that, somewhere... Someone's race car, but I don't remember whose or where I saw the pics.

--DD

Posted by: Randal Aug 12 2004, 06:44 PM

Come on Dave, you've got to remember!

Posted by: James Adams Aug 12 2004, 08:45 PM

Yeah, I've seen that too. Maybe the other Brumos car (one had a Hewland) or another historical GT.

You have to be careful taking out the bushing slop, as at some point the linkage will bind up. It is not a perfectly aligned system. Adding another support and an extra u-joint would perfect it, but unfortunately will only make it incrementally better for a lot of work.

I may try it anyway...

Posted by: Randal Sep 20 2004, 09:13 AM

Great Customer Service!

Thanks James for re-building my Rennshift and getting it back so quickly.

Randal