Front spring

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gdavis
Posts: 52
Joined: October 12th, 2012, 8:55 am

Front spring

Post by gdavis »

Going into 12 at Nelson, if I get on the brakes hard, my D-13 front end bottoms out. Does everyone have this problem at 12 because of the dip/track surface change, or do I need a new front spring? The spring in the beam is old, genuine VW, but even German steel will fatigue over time and I'm guessing this one is at least 35 years old. I have approx. 2 1/2 " ride ht. at the front. Also, where would be a good place to locate a superior quality or n.o.s. replacement, if needed?
Dietmar
Site Admin
Posts: 650
Joined: June 24th, 2006, 11:56 am

Re: Front spring

Post by Dietmar »

Greg:

the D-13 is notorious for weight transfer, so before you spend a lot of dollars, let me ask what your spring combination is at this time.
Is the set complete? Cut? One or more springs removed? Might be as simple as adding 2 of the half leafs and raising the front 1/2 "
Where is the battery- still on the front or...?

Without the above info I can not comment further.

New and used springs are available. E-mail or call and I would be happy to assist you further.

Hope this helps

Dietmar
http://www.quixoteracing.com
lucky13
Posts: 9
Joined: November 2nd, 2011, 10:15 pm

Re: Front spring

Post by lucky13 »

You probably want to ask the fast guys, but my front end doesn't bottom out over the bumps going across the pavement into 12. It is definitely a pretty good bounce and if I go across it while still crossing over to get to the right side of the track to set-up for 12, I get a decent wiggle from the back. Having the front bottom there has to be more than a little bit unnerving.
gdavis
Posts: 52
Joined: October 12th, 2012, 8:55 am

Re: Front spring

Post by gdavis »

Dietmar - I will try to contact you shortly. Thanks for your response lucky 13 - to add to the difficulty, it's also knocking me out of 4th gear and that definately is complicating things there. I apreciate both your responses to my problem.
lucky13
Posts: 9
Joined: November 2nd, 2011, 10:15 pm

Re: Front spring

Post by lucky13 »

gdavis wrote:Thanks for your response lucky 13 - to add to the difficulty, it's also knocking me out of 4th gear and that definately is complicating things there.
I had the same problem but just after the big bumps that cross the track. Just as I was getting off the brakes, turning in to the corner and getting on the throttle, I'd hit a bump and the car would hop out of 4th gear. It didn't happen every lap and that made it worse because every time it happened, it caught me by surprise.....short-term memory being what it is.... :lol:
Dietmar
Site Admin
Posts: 650
Joined: June 24th, 2006, 11:56 am

Re: Front spring

Post by Dietmar »

If it is a D-13 and jumping out of gear over a bump, you might check the front motor mount.

Dietmar
http://www.quixoteracing.com
FV90
Posts: 133
Joined: June 26th, 2006, 2:41 pm

Re: Front spring

Post by FV90 »

My old D-13 started scrapping the front (with battery in the nose). I found out that it had snapped a part of the spring pack. A new spring pack and all was good. My D13 always sat low to the ground prob cause they were designed with tall treaded tires.
jpetillo
Posts: 759
Joined: August 26th, 2006, 2:54 pm

Re: Front spring

Post by jpetillo »

My experience goes along with Dietmar's recommendation. When I popped out of gear over bumps, it only has happened when the motor mounts were loose. John
tiagosantos
Posts: 389
Joined: June 20th, 2010, 12:10 am

Re: Front spring

Post by tiagosantos »

This might not be applicable to your car but I had the popping out of gear problem when my rear 'bumper' was too close to the shifter rod.. There was some clearance, but I guess on some bumps, things moved and pushed the rod into neutral.
MarkP-2
Posts: 50
Joined: May 14th, 2012, 9:37 pm

Re: Front spring

Post by MarkP-2 »

Or maybe you don't have a dead-peddle for the clutch foot, and you're bumping or placing pressure on the clutch peddle causing
it to go into neutral when you encounter a bumpy section of track ??


Mark

P.S.: My son had the same problem several times on Sunday, but I didn't encounter it the previous day so who knows?
gdavis
Posts: 52
Joined: October 12th, 2012, 8:55 am

Re: Front spring

Post by gdavis »

My jumping out of gear problem was really screwing up 12, so I just started holding the shift lever in 4th while approaching the turn and this obviously stopped the problem. The front mounts are tight and Mark, I have recently installed a dead pedal, but haven't yet gotten used to it "being there", so your theory could be correct. I have a form-fitting seat and don't really need to brace myself much while braking, but I could be pushing on the clutch inadvertently.
Thanks to all for your suggestions and responses - it's great to get these insights.
problemchild
Posts: 901
Joined: June 25th, 2006, 9:34 am

Re: Front spring

Post by problemchild »

Many race cars run skid plates or blocks to protect the chassis when bottoming.
I have seen D-13s with steel sheet panels riveted onto the front bulkhead. You could also install bump rubbers on the shocks to ease the bottoming.
If you run quality front shocks (penske or fox) you could try raising the shock pressure .... or revalving.
You could also install a ride height adjuster and adjust your ride height.
Perhaps just re & re your spring pack but flip it so it is upside down.
Bend the spring pack.

Lots and lots of ways to deal with this issue. Laziest way is to rivet on a skid plate and ignore it.
Cheapest way might be to flip the spring pack.

Regarding the popping out of gear .....
Something is flexing enough to pull it out of gear .... find the play/flex .... front engine mount is obvious but could be bellhousing mounts too, but start by adjusting the linkage and make sure all the hangers/mounts for the linkage are not near joints, ridges, seems, u-joints, etc that will act to pull the linkage when flexing.
Last edited by problemchild on November 7th, 2012, 10:41 am, edited 1 time in total.
Greg Rice
"Happy 50th Birthday"
CenDiv20
Posts: 57
Joined: February 20th, 2007, 1:06 pm

Re: Front spring

Post by CenDiv20 »

You need a new spring pack installed in the beam. I had the same problem and replaced it.

Good thing is you have all winter to change it out.... not like its the middle of the race season.
gdavis
Posts: 52
Joined: October 12th, 2012, 8:55 am

Re: Front spring

Post by gdavis »

My current plan of attack is to change the front spring, increase ride height slightly and modify my shift linkage by replacing the steel sections with aluminum tubing to lessen the inertia forces from the weight of the stock linkage.
FV80
Site Admin
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Re: 4th gear....

Post by FV80 »

Greg,
I also ran across a situation where the car popped out of 4th on occasion - not very often, but usually at a BAD time. I had a spring at the nose cone to load the shifter towards 3/4 (stretch the spring for 1/2/R). All I did was reposition the end of the spring towards 4th gear. Voila! Problem solved. I'm guessing that the spring was pulling it OUT of 4th and moving it back a little stopped that issue.
Not sure if you have a spring or not .. but if not, you NEED one :-).
YMMV,
Steve
The Racer's Wedge and now a Vortech, FV80
problemchild
Posts: 901
Joined: June 25th, 2006, 9:34 am

Re: Front spring

Post by problemchild »

gdavis wrote: modify my shift linkage by replacing the steel sections with aluminum tubing to lessen the inertia forces from the weight of the stock linkage.
I have never heard this theory before. If a car ever came into my shop with aluminum tube in the shifter linkage, I would replace it with chrome-moly tube, the larger diameter the better. IMO, if the aluminum is strong enough to do the job, then it will not lighter enough to matter, and I personally prefer the integrity of CM tube. That's just my opinion, but I hate shifter problems!

There is a reason that a car starts popping out of gear. Find and fix the problem.
Greg Rice
"Happy 50th Birthday"
Campbell Motorsport
Posts: 20
Joined: November 28th, 2009, 8:44 am

Re: Front spring

Post by Campbell Motorsport »

If you are using a front motor mount that uses the lower tab on the front of the motor, sandwiched between 2 tabs- you may think it is tight and it is still moving. If either the hole in the case or the holes in the 2 tabs of your motor mount are larger then your bolt, you could still get movement in the extreme conditions you describe. The larger holes make it easier to assemble, but will allow movement. If you use a 3/8 bolt with 3/8 holes and tighten it, you can eliminate that potential problem area.

Larry Campbell
gdavis
Posts: 52
Joined: October 12th, 2012, 8:55 am

Re: Front spring

Post by gdavis »

Greg, I have the stock D-13 linkage which is fairly stout, but also heavy. My theory is quick deceleration combined with the bump in the track,plus the weight of the linkage is too much for the detent ball in the tranny and the result is that it pops out of fourth. The car has been doing this at Nelson even just after I had the tranny rebuilt, so I don't think it is a problem with the ball. I was thinking 6061 T-6 tubing would be sufficient as far as strength is concerned. The only issue I see is that I would have to bolt the aluminum sections to the u-joint portions of the present steel linkage.
Jim, I will check the motor mount again, but it was assembled just as the Autodynamics manual instructed, oh so many years ago.
Dietmar
Site Admin
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Joined: June 24th, 2006, 11:56 am

Re: Front spring

Post by Dietmar »

G:

What we are trying to hint at is that other D-13's with original shift rods do not have the problem that you are experiencing, so the problem is not in the weight of the rod but should be found elsewhere. Of course you are free to change the rod to aluminum, but I think you will be disappointed - but I have been wrong before.

On the D-13 front mount, a 3/8 bolt is required. The stock VW hole in the case is smaller than 3/8 so may people use a 5/16. This itself will cause the hole in the case and the hole in the mount to go oval and allow movement at the front of the case.

Dietmar
http://www.quixoteracing.com
problemchild
Posts: 901
Joined: June 25th, 2006, 9:34 am

Re: Front spring

Post by problemchild »

Greg,
Sorry, I think you need to fix a problem. That linkage has been adequate on hundreds of cars for 35-40 yrs. If you rebuild your linkage, you will likely fix your real problem, whether you determine it in the process, or not. I think that is never a bad move. I would just weld in CM tubing rather than use aluminum. It will be no heavier than aluminum, but without bolts, pins, etc. I buy 6 ft sections of CM tubing (from Mcmaster Carr) for cheaper than I can buy similiar quantities of aluminum tube. Of course, anytime you rebuild shifter linkages, it is always best to spend as much as you can possibly afford on the actual joints.
I understand this is just one man's opinion, or two, but I hate to see people spend time and money on repairs, and then waste a race weekend, and still have to make repairs again. Good luck!
Greg Rice
"Happy 50th Birthday"
BLS
Posts: 441
Joined: May 11th, 2011, 7:52 pm

Re: Front spring

Post by BLS »

http://www.stockcarsteel.com/

Much better pricing in most sizes, any length (up to 8' on website, longer lengths by phone). Considerable savings over Mcmaster in most sizes.
Barry
Old Zink FV,
'87 Citation
gdavis
Posts: 52
Joined: October 12th, 2012, 8:55 am

Re: Front spring

Post by gdavis »

I appreciate everyone's responses to my problem. I have decided to look into the motor mount engineering before I do anything else and change the linkage only as a last resort- and use the CM tubing if I follow that route. Maybe the best solution is that I should just avoid racing at Nelson, as I don"t have the problem elsewhere:lol:.
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