Front End Issue

[SCFFR]

I recently completed my MkIV roadster but have run into an issue with the LF wheel. While the body was in the paint shop, I took the go kart and had the front end aligned (used the specs in the FFR manual). When I reinstalled the body, I discovered that the left front tire rubbed the body when the wheels were turned (around the 10 o'clock position if looking at the tire from the side). I also noticed that the LF tire was more forward in the wheel opening than the other side. The RF tire had plenty of clearance and was centered in the wheel opening.

I rechecked all of the front end pieces. I verified that the FFR tubular lower control arms were in the right bracket holes (lower outboard holes), the UCA were in the proper location and the spindle adapters were correctly installed (I'm using 1995 spindles).

I put a post on the Factory Five forum and got several responses. I replaced the new 245/60-15 Cooper Cobra tires with a pair of 235/60-15 Cooper Cobra tires. This got me about an additional 1/4" clearance. I also worked the wheel opening lip and removed a portion of that.

The majority of the posts suggested that the alignment was wrong so I measured the two UCA's and discovered the LH appeared to have different arm lengths (smaller) than the right one. So, I adjusted the arms on the problem, left side to be the same length as the right side knowing I had messed up the alignment.
This morning I took the car back to the alignment shop and explained the problem. I had hoped that the clearance problem could be fixed with the caster angle. Before he started on the front end, he centered the front wheels and measured the distance from the front to rear hubs on both sides. The right side is 3/4" shorter than the left which explains why the left side tire is more forward in the wheel opening. He then measured the caster and found the right side to be 3 degrees (positive) which is what he had set it in the go kart stage. The left side was 5 degrees (positive) which meant adjusting the caster for more clearance was out of the question.

His suggestion was to either move the holes in the frame brackets (where the LCA's attach) or have the LCA modified to shorten the rear tube. This would move the bottom of the spindle rearward so the tire would be centered in the wheel opening to match the right side.

The only positive thing is that the car drives perfectly straight. The is no shimmy or shake and absolutely no tendency to pull either left or right. The mechanic even commented as we pushed the car over his shop floor that it rolled perfectly straight.

I asked if he should adjust the right side caster to match the 5 degree setting on the left side and he said that since it was steering fine with no issues to leave it as is.

Any suggestions as to why the wheelbase would be off 3/4" from side to side? We centered the rear end and with the non-adjustable arms on the 3-link system, I would think the rear end is pretty much fixed in place. Also, the rear tires are perfectly centered in the wheel openings. I know the FFR tubular LCA's are welded in a jig but is there any way the one I have on the left side could be defective?

Just wanted to mention that the mechanic is highly experienced with 50+ years of running his own shop and racing multiple dirt track, circle track, modified and drag cars. If you are having a problem with any type of front end/alignment, he is the guy to see so I think his credentials are solid.

Thanks,

Ron

[skullandbones]

Anything is possible I guess. But doesn't it bother you where that 3/4 inches was lost or gained? It would drive me crazy. If the mechanic measured from hub to hub that still doesn't tell you if you have a parallelogram, rectangle, or trapezoid making up the 4 corners. So did he reference off the chassis to square everything up? I would want to know that the control arm bracket was 3/4 inches to far forward (which I think is the assumption). In other words, you would have a 90.75 inch wheelbase on the drivers side and 90.0 on the passengers. If that's true then cutting the LCA or moving the rear hole might be the only way. But I don't think you know that for sure. I've been doing a lot of changes on my front suspension and I can tell you the only thing I've learned for sure is that you really need to be square with your eyeball even with the component to get an accurate measurement. It's hard. I would recommend doing all the measurements with the roadster on a lift at eye level. You didn't mention if the LCAs (rear tube) is actually different or I missed that. Did you use 60 series tires to fill the space better. I have 55s on mine for a start and I am thinking they may be a bit small except the clearances are pretty tight and I'm still a 1/4 inch too high in front. Just wondered. WEK.

[WIS89]

Ron-

I am now wondering if you have the proper LCA on the left side. Perhaps you should take highly accurate measurements of the arm and call tech support to ensure you received the correct LCA. It easily could be two right sides, or a 33 LCA, or some other "simple" mistake that is causing a great deal of head scratching. The idea that the wheelbase is off seems highly suspect. It my head, it just seems that everything points to the LCA.

Let me know what you think... as always, good luck!!

Regards,

Steve

[SCFFR]

Thanks guys.

I'm definitely scratching my head over this one. Both of the rear wheels/tires and the right front are centered properly in the wheel openings...............only the left front appears to be located more forward in the opening. The left side wheelbase is 3/4" longer than the right side. Based on the positioning of the rear and RF wheels, the body appears to be located properly on the chassis. The lip of the front cowl is just a hair from touching the dash and the rear is snug against the lower trunk panel so the body can't be moved forward at all.

The FFR tubular LCA's appeared to be the same so I didn't ask if they were left and right sided. Are they?

I watched the guy at the salvage yard pull the front spindles from a 1995 Mustang so I know they are a "set" from the same car.

Hopefully one of the tech guys will chime in with some suggestions.

WEK - I am using the 60 series tires (Cooper Cobra) but I did replace the new 245's with a pair of 235's (a $270 change due to this issue). I picked up about an extra 1/4" clearance.

Ron

[Jeff Kleiner]

Steve,
The LCAs are the same for left and right.

Ron,
Got your PM. At this point I'm mostly out of ideas and in agreement with WEK that it's going to take some careful measuring to try to determine where the variation is. That would mean starting with the lower arms to verify that the tubes are the same length on both sides and located exactly alike on the bushing sleeves. Measure from the center of the ball joint (grease fitting)to a common location. It would seem more probable that an arm is out of whack rather than the chassis. Remember there are 4 tabs for each LCA; while it is not impossible that all 4 are mislocated I'd think that the jig would make it pretty unlikely. With that said if both arms measure the same and you start investigating the chassis a quick check would be to compare the distance of the LCA tabs from the front X member &/or the ends of the frame tubes. To go farther, rather than doing it on a lift I'd keep it on the ground and make a reference line on the floor directly down from the outside of both frame tubes. I'd then plumb down to the floor along this line from the center of the rear axle and from the LCA frame tabs. Compare those dimensions side to side. If you find the 3/4" you'll have to start checking other reference points such as the rear LCA mounting points or front UCA mounts to try to determine where the descrepency lies.

From what you discovered earlier I thought alignment would take care of it...sorry it didn't turn out to be that easy Keep us posted and good luck.

Jeff

[skullandbones]

Ron,

Here is a site that will better illustrate what you will be going for with the transfer of the measurements to the floor (Jeff made a good point).

http://www.onedirt.com/tech-stories/...r-roll-center/

The article is for a different purpose but the process is the same. See the illustrations of the plumb bob measurements and the chalk lines on the floor. Once you get the accurate template of your frame you should be able to find that pesky 3/4 inch.

See you later,

WEK.

[SCFFR]

Thanks again guys.
Yes, I was hoping that the alignment would fix the clearance issue but no such luck. I had already done a few measurements on the LCA mounting tabs and all looked fine but will start over again. I agree that with the jigs used in the welding process, there shouldn't be anything out of line but you never know.
Will concentrate on the LCA's first since that would be "easier" to correct if one was out of whack.
There definitely must be something wrong since the car steers perfectly with the caster setting so different from side to side.

Will keep every one update on my measurements.

Ron

[SCFFR]

UPDATE:

Spent the last couple of hours taking careful measurements of the frame and LCA points.
Here's what I did:
Had to remove the wheel since the center of the lower spindle (grease fitting) was inside the wheel rim.
After removing the wheel, I lowered the chassis onto a 5" block (did this on both sides)
Using a plumb bob, marked the location of the front and rear LCA mounting brackets and the center of the LCA spindle.
Drew a line through the two bracket mounting points.
Used a framing square to locate the spindle center.
Result: the left side spindle center is 5/16" forward than the corresponding point on the right side. I guess this explains why my left wheel has the clearance/wheel center issue as compared to the right side. This measurement also supports the difference I found in the wheel base (left side is 3/4" longer than right)

Some may say this amount is not an issue however if I could get the center of the spindle on my LCA to match the same dimensions as on the right, my left wheel clearance would be perfect.

I guess my solution is to see if I can get FFR to make me another LCA unless you can think of anything else.

Ron

[skullandbones]

Steve,
The LCAs are the same for left and right.

Ron,
Got your PM. At this point I'm mostly out of ideas and in agreement with WEK that it's going to take some careful measuring to try to determine where the variation is. That would mean starting with the lower arms to verify that the tubes are the same length on both sides and located exactly alike on the bushing sleeves. Measure from the center of the ball joint (grease fitting)to a common location. It would seem more probable that an arm is out of whack rather than the chassis. Remember there are 4 tabs for each LCA; while it is not impossible that all 4 are mislocated I'd think that the jig would make it pretty unlikely. With that said if both arms measure the same and you start investigating the chassis a quick check would be to compare the distance of the LCA tabs from the front X member &/or the ends of the frame tubes. To go farther, rather than doing it on a lift I'd keep it on the ground and make a reference line on the floor directly down from the outside of both frame tubes. I'd then plumb down to the floor along this line from the center of the rear axle and from the LCA frame tabs. Compare those dimensions side to side. If you find the 3/4" you'll have to start checking other reference points such as the rear LCA mounting points or front UCA mounts to try to determine where the descrepency lies.

From what you discovered earlier I thought alignment would take care of it...sorry it didn't turn out to be that easy Keep us posted and good luck.

Jeff

Even with the variation you've found, you still need to follow the above and do some more verification measurements. The long measurements from the chassis corners will give you a more reliable (less relative error%) number. If the chassis measurements are good and everything is square, then you can concentrate on the LCA issue. Those measurements should reinforce what you have done already.

BTW, did the alignment guy mention "setback" of your right and left front tires (it should be 0)? Because if you do have to cut and reweld the LCA on the left, you should get some setback and you would expect that to be reflected when comparing the original alignment.

[SCFFR]

Thanks for the reply.
I did measure the outside of the main chassis tubes and the location of the very front and rear brackets and transferred these to the garage floor. The distance from the front bracket to the rear is exactly the same side to side. The distance from the outside edge of the chassis tube to the center of the lower spindle is exactly the same side to side.
The difference is the distance from the center line of the lower spindle (where it intersects the line of the main chassis tube) to the front bracket.
It appears that the bracket locations are the same, it's just the left lower spindle center is 5/16" more forward.

I was hoping a FFR tech would respond with their ideas and/or suggestions. I am going to ask for a replacement tubular lower control arm and replace the suspect one I have on the left side. I would rather do that first before cutting and welding the tube arms to relocate the spindle center.

Thanks,

Ron

[SCFFR]

Would appreciate some input from a Factory Five Tech.

Thanks,

Ron

[CHOTIS BILL]

I have found calling them works best. They are very willing to take what ever time it takes to get things sorted out.

Good luck,

Bill Lomenick

[SCFFR]

Bill,

Took your advice and gave them a call.

Talked to Jay twice to describe my problem over a week ago but haven't received any reply/explanation.

Ron

[skullandbones]

Bump.

[SCFFR]

Thanks for the bump.

I'm disappointed that it's been over two weeks since I first posted my issue and still haven't received any kind of definitive response from FFR. In talking with Jay, the impression I got was that it was a "body position" issue which although is certainly a cause, I don't think it is the answer in my case for the following reasons.

My body is pushed as far forward as it will possibly go. The bulb seal on the lower trunk panel is completely compressed and the cowl lip is pushed against the dash panel.
Both rear wheels and the RF wheel is properly centered in the wheel opening. Only the LF is the problem (too far forward in the wheel opening).
The wheelbase on the left side of the car is 3/4" longer than on the right side
Using plum bob and levels, I transferred key chassis/LCA measurement to the garage floor and found the center of the lower ball joint on the left side LCA is 5/16" more forward than on the right side. If the center of the ball joint on the left side was the same as on the right side, the extra 5/16" would bring my wheel more to the center of the wheel opening.
The alignment mechanic who had plenty of race chassis experience said that either the LCA was "off" or the brackets on the chassis where the LCA attaches were out of position.
I am having to run 5 degree of caster on the LF wheel to move it rearward far enough to keep from rubbing the front of the wheel opening (I have 3 degrees on the RF).

I guess I was hoping that I could get a replacement tubular LCA and see if it would help remedy this problem.

Ron

[SCFFR]

Would appreciate some feedback from FFR.

Ron

[rich grsc]

If you measure the lower control arm, and it isnt the same on both arms, then send it back, FFR will replace it. Very simple to determine if it was mis welded. One of mine was twisted where it bolts to the frame, putting one of the bushings in a serious bind. Set pictures to FFR, sent me a new one, and a return postage slip. No questions asked!!!

IMG_1480_zpsaa3f2973.jpg

[SCFFR]

That is what I was hoping to happen in my case. I did the measurements off the chassis and determined the left lower ball joint center (i.e. measured from the grease fitting) is 5/16" more forward than the right side. I clearly stated this and other info in my posts and also told the FFR tech when I talked to him. Was told they would discuss with engineers and get back with me. That was a couple of weeks ago.

Thanks,

Ron

[realtorpi]

Ron, did you ever receive an answer. I seem to have the same problem and was hoping there was a solution.

Tom