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250 V8 20 MPH vibration

classiclife
Classic Wise Man
Classic Wise Man
Posts: 1601
Joined: Wed Sep 05, 2018 9:55 am
Location: Ridgewood - East Sussex
Contact:

Re: 250 V8 20 MPH vibration

Post by classiclife »

Hello Richard.

Frustrated I'm sure !!

Your quote: As I noted earlier the prop shaft was rebuilt by a professional company so the UJ's etc are new.

Professional company or not, there can still be issues with products which they may not have picked up at the time or may well have failed within a very short time of the car being driven.

You say the vibration gets worse up to 30mph and then subsides at approx. 40mph - this certainly implies there is a resonating issue or something is most definitely out of balance. One could easily suspect the propshaft being that. I've known many classics stumble due to poor quality UJ's or not being fitted properly. Every professional has an off day.

Personally, I would focus on the UJ's and replace them with a known quality brand that you have purchased - these can then be supplied to the fitting company. It really is a case of sifting through likely suspects.

Good luck.

Regards.

Richard.
1968 Daimler V8-250 Saloon
DLOC East Sussex Branch Secretary
DLOC 2.5L V8 & V8-250 Registrar - https://www.dloc.org.uk/v8-250
DLOC 2024 International Rally - https://www.dloc.org.uk/rally-2024

JDB
Posts: 170
Joined: Sun Mar 13, 2016 11:35 am

Re: 250 V8 20 MPH vibration

Post by JDB »

I had a similar problem on an MG Midget, turned out to be the splines on the hub/wire wheel interface (never really ascertained whether the wear was on the wheels or the hubs). Swapped to standard hubs and alloy wheels to cure it.
Best of luck, JB

Flinty
Posts: 90
Joined: Mon Sep 24, 2018 7:34 pm
Location: Scarborough

Re: 250 V8 20 MPH vibration

Post by Flinty »

Hello Richard.
Any chance of getting it onto a rolling road?
You could then isolate either the front or the the rear.

Steve.

DickSpeedy
Posts: 46
Joined: Sun Mar 20, 2016 2:07 pm

Re: 250 V8 20 MPH vibration

Post by DickSpeedy »

I have subsequently removed both rear wheels and run the car on stands. You can still feel the vibration especially through the steering wheel.

I have disconnected the exhaust brackets closest to the engine still have the vibration.

The service manual states that the gearbox mounting plate should be refitted with the same shims that came out when it was disassembled. I don't recall removing any shims and can't find any listed in the parts book. I am considering making up two 10 mm shims and lowering the gearbox slightly. What do you guys think?

Flinty
Posts: 90
Joined: Mon Sep 24, 2018 7:34 pm
Location: Scarborough

Re: 250 V8 20 MPH vibration

Post by Flinty »

Richard, Just another thought, Has your car got the original cooling fan,? if so it is a very heavy and solid bit of kit, Is it loose, have the rubber bushes been replaced.

Steve.

Superfly
Posts: 30
Joined: Wed Aug 08, 2018 8:02 pm
Location: Leicestershire

Re: 250 V8 20 MPH vibration

Post by Superfly »

Hello Richard

I had a similar situation with my 250 V8,same area of the car,very frustrating it was too, my solution might not cure your issue but won't hurt to check out.
I had replaced all the mounts with quality replacements before finding the issue.

Check the coils are not binding on the spring that sits in the gearbox mounting and the locating pin In the mounting is not protruding too far out underneath.
Mine was coil bound in effect giving a solid mounting and lots of vibration!
The Repair manual does seem a little vague on this.

I loosened the rear engine mount on top of the bell housing.
Jack the gearbox up until there is about 10mm of the locating pin protruding from the bottom of the gearbox mounting.
Adjust the rear engine mount until it just locks up,at this point I found I had quite a bit more thread showing than previously once the Nyloc nut was refitted.When all locked up remove the jack holding the gearbox up.

The Repair manual shows this thread almost flush with the Nyloc in the diagrams,in my case this was a bit misleading.

Anyway the upshot of this is,the mounting is no longer coil bound and no vibration!.

If yours is ok,the only other thing I can think of is the centre bearing mounting may need shimming as this sometimes can reduce vibration.

Stu
1968 Daimler 250-V8 Saloon

A.N.Other
Wide Man
Wide Man
Posts: 551
Joined: Tue Feb 16, 2016 12:45 pm
Location: Leeds

Re: 250 V8 20 MPH vibration

Post by A.N.Other »

Hello Stu,
Hope the resto has gone well. Retirement suits me, being in the garage is better than being on presses.
Colin,
I may be slow but I’m rough as well !

DickSpeedy
Posts: 46
Joined: Sun Mar 20, 2016 2:07 pm

Re: 250 V8 20 MPH vibration

Post by DickSpeedy »

Thanks for the tip regarding the fan. Mine has the original automatic fan control removed and a plate welded in the center. I will remove it and see if that makes a difference.

I replace the engine stabiliser bushes today but that made no difference still have the vibration.

If the fan solution does not work I will get back onto that rear gearbox mounting and check out the spring yet again.

Thanks guys I'm feeling more positive with your valuable feed back.

DickSpeedy
Posts: 46
Joined: Sun Mar 20, 2016 2:07 pm

Re: 250 V8 20 MPH vibration

Post by DickSpeedy »

Hi Guys, many thanks for your input. I must mention all your names starting with Chris, TJT, Richard, JB, Steve, & Stu. I hope I have not left anybody out.

The problem was the FAN! The Viscous coupling had been removed and a new center welded into the fan. It was not welded directly in the middle.

I shall now look for a solid fan maybe from a Dart or have my one re manufactured by an engineering shop.

This has taken 3 months out of my life!

Thanks again guys and thanks to the DLOC forum.
Dick

classiclife
Classic Wise Man
Classic Wise Man
Posts: 1601
Joined: Wed Sep 05, 2018 9:55 am
Location: Ridgewood - East Sussex
Contact:

Re: 250 V8 20 MPH vibration

Post by classiclife »

Hello Richard.

Congratulations.

Well done for persevering, an issue which certainly had to be sorted and relief at last. Steve's mention of the fan was certainly on the money - good on you Steve.

All-in-all, I think the fan being the problem is a "better" result than what may of lay ahead !!

Regards.

Richard.
1968 Daimler V8-250 Saloon
DLOC East Sussex Branch Secretary
DLOC 2.5L V8 & V8-250 Registrar - https://www.dloc.org.uk/v8-250
DLOC 2024 International Rally - https://www.dloc.org.uk/rally-2024

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