Sven: Endurance Miata

What I'm almost certain the noise isn't. 

Downpipe hitting the bell housing

Diff drive flanges hitting the exhaust

Driveshaft yolk hitting the PPF

I've had a couple suggestions that it may be the diff and while it doesn't sound like it's coming from the rear that doesn't mean it's not. I'm waiting for confirmation but I believe this is a diff out of what was a solid race car before it was wrecked. Maybe the wreck broke something? 

Can you get the car up in the air and under it with it running in gear (be safe!)? Grab a stethoscope and start listening and hopefully narrow it down.

adam525i said:

Can you get the car up in the air and under it with it running in gear (be safe!)? Grab a stethoscope and start listening and hopefully narrow it down.

Done that. Can't replicate the noise in those conditions. It only happens when taking off moving forwards or backwards, almost solely when the wheels are turned. 

I just went out and drove it again with the idea in mind that it's the diff and...I'd buy it. It's not welded as I can chock one wheel and spin the other. Just a blown out 1.6 LSD? 

AxeHealey said:

.. It only happens when taking off moving forwards or backwards, almost solely when the wheels are turned. 

Are your eccentric/alignment bolts on the LCAs good and tight? Did you check the aftermarket bushings in the UCAs that did not appear to have good  fitment?

In reply to David_H :

All good questions. It has not been aligned yet but I do believe I tightened down all the eccentrics once on the ground but I'll confirm today. 

I confirmed many times with the company that they eventually got me the right sleeves and once tight it all seemed normal. In the couple trips I've taken up and down my street, it seems to handle great. No slop that I would have expected from the looseness of the sleeves.

Last night a buddy came over and while he was pulling away to replicate the noise I laid down behind the car and could see the diff jumping around along with the noise. Doesn't mean for sure it's the diff but seems to point more directly at the driveline at least. 

Edit: Goals for today are to 1) Check fluid in the diff  I realized last night that I never did that... 2) Put fresh fluid in the diff 3) Per David_H's suggestion, make sure I didn't miss any LCA bolts. I signed up for the autocross this weekend. I figure if I need a new diff, I already need one and breaking it on Saturday isn't that big of a deal. I'm just so eager to use this thing. 

To be ready for Saturday I need to bleed the brakes and hook up the fan(s). 

Lunch update - diff was full, possibly overfull. The fluid was definitely shimmery but no big flakes or chunks on either the magnet or in the drip pan. If I saw this level of shimmer from engine oil I'd be really concerned but I don't think I am considering it's a differential that has who knows how many races on it. 

Refilled with Redline 75-90.

Edit for early afternoon update: Fresh fluid seems to have fixed it... I may have gotten it to do it once but I did a lot of starting and stopping and turning around and what not and it seems totally normal. 

Change fluids in parts you don't know the history of. 

The autocross test went well. A small leak showed up as I was trying to scrub the years of rust and grime off the brakes but zip ties saved the day.

Transponder mount, done. 

I *think* the mounting holes I used are for the factory under tray. I found one locally that I should be picking up later this week once I can be back in public. 

This poor car has been so hacked (see gaping hole in picture above) and the provisions for mounting the bottom of the front bumper cover are totally gone so I need to figure that out. Eventually I intend to make a bigger under tray out of aluminum but right now the focus is on getting to PittRace in a month. 

By the way, I used the auxiliary power as provided by Mazda (for timing?) as the 12V and a threaded hole for something in the engine bay for the ground. Works perfect for the transponder. 

I was noodling on how to mount the fire bottle and started digging through my scrap bin to find this. 

I can't recall where it came from but it's just about perfect. 

I need to bend the tabs to be flush with the trans tunnel and also need shorter screw clamps but I like this. 

Final mounting. The instructions said the bottle should ideally be perpendicular to the car or, second best, pointing at the back of the car. I want it tight to the tunnel for weight distribution. Hoping to have the lines run this afternoon - rain dependent. 

I got this far. Apparently my brake tool can't just make a normal 37* flare, only bubbles.

Used a factory stud to support it behind the dash and right by the nozzle will be zip tied to the column.

OK. Lines run. Technically the manufacturer says to not mount the nozzles vertically but the only reason they give is to keep them from getting dirty. I really like the idea of this positioning to have as much coverage of the engine bay as possible. 

If someone knows of another reason it shouldn't be vertical, let me know. 

I bought some bike shifter housing to use the pull cable I found in our parts stash. It may take some finagling but it should work. I also spent some time yesterday noodling on how to install the Flagtronics system.

That's a frame for running a front plate, great job repurposing it!

In reply to johndej :

Thanks!

Good progress yesterday, mostly in the form of finishing the fire system. Should be the last pics that I post of it.

I also got all new hoses and clamps put on for the cooling system as well as removed the airbag modules which would periodically beep incessantly. 

AxeHealey said:

What I'm almost certain the noise isn't. 

Downpipe hitting the bell housing

Diff drive flanges hitting the exhaust

Driveshaft yolk hitting the PPF

 

I've had a couple suggestions that it may be the diff and while it doesn't sound like it's coming from the rear that doesn't mean it's not. I'm waiting for confirmation but I believe this is a diff out of what was a solid race car before it was wrecked. Maybe the wreck broke something? 

Sounds a lot like a problem I chased on my brother's miata. It ended up being bad drive shaft u-joints. Have you checked that? My bad if you already mentioned it. Just found this thread. I love racecar build threads!!!

In reply to MaxC :

Thanks for the suggestion! They don't seem to have an unusual amount of play and ever since changing the diff fluid I haven't experienced the issue. 

Yesterday I got the rattly heat shield cut, pried and otherwise muscled off the downpipe. Really hoping it was fiberglass insulation in there...

With just two weeks to go, I'm going to put the truck outside and move Sven into the garage to expand the time I have to work on it (it's just about dark now by the time we get the kids to bed) along with not allowing weather to play a role. Brakes, paint/body work, alignment and various other little things to check off the list before next Friday. 

Fenders painted. They came out worse than normal for my front yard paint booth but they're black and shiny-ish.

More painting on work breaks from all day calls. No more purple filler panel. 

I also noticed that I needed to paint an edge on the fenders, laid them down on the painted side aaaannndddd messed up the fresh paint. So they got another coat that went on terribly... and then got another coat which is currently drying.

I guess it's been 9 days since an update on Sven. A lot has happened. Bumpers painted (more on that in a moment), rear arches "fixed".

They are full on OK. I decided to not weld up the inner and outer fender because these poor quarters were so mangled that if I want to make it nice sometime, I'll just replace a big chunk. I just hammered them close to straight and slathered seam sealer on the inside. You can see the fresh brakes in that pic too. 

I then continued my relationship with rattle cans. I had grand ideas of a sort of hoop of Porsche style stripes matching the colors of the E21 but I realized I just didn't have the time to get it laid out and looking right so I went with...this.

The satin spiced amber is a really finicky paint for some reason. Those that follow the Small Axe thread will know that it gave me fits on the E21. Well, it did again on the trunk when trying to fade it over the yellow. Close up it looks like E36 M3 but that's OK.

It got aligned, various little things spruced up, fixed, cleaned or otherwise to end up with...

That pic reminds me that I also needed to find a way to secure the bottom of the front bumper since all the support was hacked out for a previous turbo system install. What I came up with is a sort of pseudo splitter. It's just made out of sheet steel bolted to the bumper and the factory under tray. Not a long term solution but, fingers crossed, it should do for now.

The truck is all loaded up. I head out first thing tomorrow for PittRace.

PittRace recap. It was going great, until it wasn't.

None of my normal racing group was available for this weekend to I roped in a friend from rallycross who had been on track once before. He wanted a bit of extra seat time so we signed up for the Friday practice session. I got to the track around 10:45 and we got to work unloading and setting up. After getting checked in for practice, I took the car straight to tech. The line took a while and we ended up needing to address a few things which meant a trip to the hardware store. Straps on the hardtop window, metal covering holes bigger than 0.5", adjustment to the window net and some other small thing that I can't remember. We finally had the car ready to go for the last run session. I took it out first just to make sure it felt right and then brought it back in for my friend to go. He had it out for short run and then we packed up and called it a day and went to a local bar I've made a habit of going to when at Pitt. Gorgeous sky that night.

Saturday morning was cool and dry with rain expected. We noticed the lug nuts had gotten very loose after the practice on Friday. Pulling up to our pit stall, the car started making an absolutely horrible noise. Turns out the alternator adjuster had popped off. So instead of starting second on grid, we ended up dead last. I started the race with a pretty good stint. The last time we ran the Spec car without a turbo at Pitt our fastest time was a 2:17. I turned a 2:16 that session. My friend hopped in for a short-ish stint and felt much better than the day before. Since it was just the two of us, I then got back in and ran for a bit over 2 hours, turning a 2:14 at my best. There were tons of yellow flags, code 35s and actually two red flags in my sessions on Saturday but some good blocks of green laps where I got into a nice groove. We had to tighten the lugs after the first two stints but then I upped the lbs and we didn't have another issue with that all weekend. 

When I brought the car in after that stint, the alternator was loose again and it started to rain. It then continued to rain and rain harder and harder until they red flagged it and called it at about 4:30. My friend got a nice welcome to racing in the rain. It was sloppy. 

This morning we checked the car over and it was time to get back at it.

The track was moist but seemed to have full grip but man people were on some E36 M3 this morning. I ran for just under an hour and a half that first stint and it had to have been under caution for half the time. He ran a nice stint and then I was back in the car for about 2 hours. I left to go fill the fuel jugs and the truck for the trip home this afternoon. Once I was back at our paddock I noticed the track was under caution. Looked out towards the esses and saw poor Sven hooked to a tow truck. My friend lost it coming out of the esses and introduced Sven to the wall.

At first I thought there was a chance of just bending stuff out of the way and getting back out there but the control arm is totally bent. It's an unfortunate way to end an otherwise awesome weekend and sucks that the car didn't even make it through it's first race weekend without real damage. It's definitely fixable but will take some persuasion of the kinked inner fender well to bring it back straight. Not sure if I'll have time to fix it before it goes into storage for the winter. I guess we'll see.

Damage assessment. 

There is some extremely wrinkled and kinked sheet metal but by my eye, the places that matter are unaffected. I think that a combination of pulling it with a ratchet strap attached to a tree or something and hammering will get it back to a reasonable place. Not certain though with how kinked it is. Worst case I guess I find one in a junk yard to cut that corner out of and weld it in. 

A big question I have at the moment is whether or not the bottom of the strut is bent or if the bolt is just crooked within the bushing. I don't know exactly how they are set up so finding a replacement for just the one could prove difficult. 

OK who was I kidding. Of course I'm going to try to fix it before storing it for the winter. Strapping a car to a tree is a reasonable way to spend a lunch break, right?

In that last pic, you can see where the sheet metal actually tore on my last tug against the tree. If the thing hadn't been so hacked up in that area before it wouldn't have happened but, oh well, just need to weld it back up. Once that's done I should be able to pound it back straight enough and then on to figuring what in the suspension needs replaced. 

I didn't have a whole lot of time to work on cars this weekend but spent a few minutes here, a few minutes there to get the suspension off the driver front. I'm pretty sure the top arm isn't bent, the bushing just moved on the sleeve but I'll compare it to a non-bent one.

The bottom shock mount also seems fine. There's a chance it's sllliiiggghhtttlllyyy tweaked but I think it's well within the straight enough realm. I do have a new bushing coming from Summit though. I was hoping to get it done for a track day this Friday but I'm traveling part of this week so I don't see that happening.

I thought this pic would be interesting to some people. Even this tiny piece of metal protruding in front of the bumper is experiencing a downward force. Probably obvious but still cool to see. I suppose that's why splitters aren't made from thin sheet steel and have good support...

I determined that none of the mounting points on the sub frame are bent and the upper arm was fine too. The bottom shock mount may be slightly bent but I decided it was well within send it range.

It all went together easily and it looks right-ish so I'm thinking after an alignment it'll be just fine.

This afternoon I threw on the straight fender I bought and I've still got to get the front corner moved out and up.

It looks much closer to straight without the fender on but it's actually closer than it appears since the mount needs to be bent back. I'm thinking to move it up I'll just try jacking it.

Edit: I also removed the lower fender bolt that broke off and cleaned up the threads.