Ive followed this forum since its inception and hope to run Sp. e 30 in 07; right now I am sharpening my skills in HPDE’s. I have built up my car along Spec e 30 lines…its a 90 325i coupe w/114k.
Here is my issue w/ the car: it has run about 6 DE’s well. w/ no issues but late last season a vibration began that is mild…it is felt slightly in st wheel and also a bit in chassis…its hard for me to pinpoint. All suspension is new except for tie rods , rt lca,… flex disc and center support bearing is also orig. Can any1 help guide me to the possible culprit? I have changed out wheels and tires to rule them out . Braking is solid, to help rule out warped rotors. Examination of tie rods shows minimal play…lca appears ok. I will change out tr’s and lca this week. Flex disc and csb look ok. Rear sf bushings are new, rtab’s are new. This vibration only happens at 85 on up, no other symptoms…and again its mild but a new devt. I dont want to have to spend uneeded cash if I can help it…thanks so much!
advice/insight hoped for: vibrations
take a look at the diff mounting bushing. is the vibration wheel speed dependant or engine speed? in other words get up to speed and then coast in neutral. if the vibration stays it likely is in the wheels or suspension.
Also check out your engine and trans mounts. The stock units are flimsy rubber that WILL break under track use. It might be alittle hard to see if you’ve got a mount that’s cracked. Rock the engine fwd and back and see if any daylight appears.
If the car is going to be a racer or used for HPDE on a regular basis, get a set of Erethane motor and Trans mounts
brain wrote:
[quote]Also check out your engine and trans mounts. The stock units are flimsy rubber that WILL break under track use. It might be alittle hard to see if you’ve got a mount that’s cracked. Rock the engine fwd and back and see if any daylight appears.
If the car is going to be a racer or used for HPDE on a regular basis, get a set of Erethane motor and Trans mounts
https://secure5.nexternal.com/shared/StoreFront/default.asp?CS=ireland&BusType=BtoC&Count1=866329371&Count2=783469796[/quote]
Bingo. I forgot this part. Also look on the drive shaft for evidence that the little plate of steel that was welded on for balancing may have fallen off.
My money is on the driveshaft. You typically feel it throughout the car and not just the wheel or the pedals. It sure would be nice if you could lube the u-joints every once in a while.
Ryan
rshand325 wrote:
[quote]My money is on the driveshaft. You typically feel it throughout the car and not just the wheel or the pedals. It sure would be nice if you could lube the u-joints every once in a while.
Ryan[/quote]
It could be the rear u joint…it is a good idea to change the engine and trans mounts anyways…but I bet it is the rear u joint…
Al
Your advice seems to cover some significant spots…some I had not known about. Tranny mounts are new upgraded units from BW, engine mounts are new poly from IE, so we are good there. Ill do a check in gear and out of gear also, and look at diff bushing.
Ill check drive shaft for sure…some questions on that:
- where to look for that balancing item you mentioned on ds?
- The u jt you mentioned…is that back by ds/diff connection or up frt by tranny/ds connection?
great help//////// very much appreciated!
FARTBREF wrote:
[quote]rshand325 wrote:
[quote]My money is on the driveshaft. You typically feel it throughout the car and not just the wheel or the pedals. It sure would be nice if you could lube the u-joints every once in a while.
Ryan[/quote]
It could be the rear u joint…it is a good idea to change the engine and trans mounts anyways…but I bet it is the rear u joint…
Al[/quote]
oh I see you say REAR u jt…is that a replaceable item?
joelrkaplan wrote:
[quote]Your advice seems to cover some significant spots…some I had not known about. Tranny mounts are new upgraded units from BW, engine mounts are new poly from IE, so we are good there. Ill do a check in gear and out of gear also, and look at diff bushing.
Ill check drive shaft for sure…some questions on that:
- where to look for that balancing item you mentioned on ds?
- The u jt you mentioned…is that back by ds/diff connection or up frt by tranny/ds connection?
great help//////// very much appreciated![/quote]
can’t tell you where it wshould be because it would depend on how the shaft needed to be balanced. just run your hands around on the shaft and you will find it. OR you will feel the spot is used to be by the welds. It is a thin piece of sheet steel…looks like a patch.
joelrkaplan wrote:
[quote]FARTBREF wrote:
[quote]rshand325 wrote:
[quote]My money is on the driveshaft. You typically feel it throughout the car and not just the wheel or the pedals. It sure would be nice if you could lube the u-joints every once in a while.
Ryan[/quote]
It could be the rear u joint…it is a good idea to change the engine and trans mounts anyways…but I bet it is the rear u joint…
Al[/quote]
oh I see you say REAR u jt…is that a replaceable item?[/quote]
I have always been under the impression that they are not replaceable parts. I have seen re-man shafts that do have replaceable, greasable U joints but they are in the 500.00 neighborhood.
nasaregistrar wrote:
[quote]joelrkaplan wrote:
[quote]FARTBREF wrote:
[quote]rshand325 wrote:
[quote]My money is on the driveshaft. You typically feel it throughout the car and not just the wheel or the pedals. It sure would be nice if you could lube the u-joints every once in a while.
Ryan[/quote]
It could be the rear u joint…it is a good idea to change the engine and trans mounts anyways…but I bet it is the rear u joint…
Al[/quote]
oh I see you say REAR u jt…is that a replaceable item?[/quote]
I have always been under the impression that they are not replaceable parts. I have seen re-man shafts that do have replaceable, greasable U joints but they are in the 500.00 neighborhood.[/quote]
…thanks. Yes I just found out they(u jts) are really not replaceable in the real world altho it is possible to do. Re man DS go for 350 on up w/ replcble items as you said. Oh well, time to get under car again. Its funny, I moved into a condo complex 2 yrs ago…it was built for seniors in their 80’s and only recently accepted whippersnappers…and all my neighbors ever see of me(on my days off) is me under this car. Wonder what they think …
Joel,
You might try talking to these folks:
Driveshaft Services
1410 Commerce Blvd Suite H, Sarasota, FL 34243
(941) 360-2490
(941) 360-2449 (fax)
(866) 360-2490 (toll-free)
Email: driveshaftkim@hotmail.com
They made a custom driveshaft for me a few years ago. Ask for Scott or Brad. I had an entire driveshaft manufactured for $350 - and it was perfect!
Ed