Polyurethane bushings

[ridgeliven]

I just got a shipment of Polyurethane bushings in from Autobush in the U.K. It's a new product of theirs that just came out and the pricing is very competitive at $113 per full set. That includes front wishbone upper and lower bushes and rear wishbone inner and outer bushes. You can check them out on ebay or I can send you some photos directly if your interested in some. Thanks Brent

[miked]

Brent,

sounds a very keen price. Please tell us more. Could not see them on ebay.

Mike

[RotoFlexible]

I noticed Brent's bushing offer last night and just checked autobush.com. (Go to Brent's store, Vintageforeignparts, on ebay, or find item 200126910477.) I am in the market for bushings and these are very price competitive against TTR or RD Enterprises (probably the same bushings).

My concern is that this company appears to be new to the market and have no track record that I'm aware of. I would worry about fit and, once in the car, physical characteristics that affect handling and road feel. Any thoughts? At this price, I'm willing to be a guinea pig.

[RichardS]

Try this link for more info

http://home2.btconnect.com/davidgeraldtvr/index.html

Richard

[RotoFlexible]

Try this link for more info

http://home2.btconnect.com/davidgeraldtvr/index.html

Richard

This turns out to be the same as autobush.com. I guess it is a small specialist outfit.

In his ebay offerings, Brent notes that these are made in China using American polyurethane. That's not necessarily a problem, but a lot of stories about adulterated Chinese products (wheat gluten and toothpaste, to name two) have been in the news lately. I don't know if it possible (or profitable) to adulterate polyurethane, but it's something to consider.

[MintSprint]

For those who haven't heard of him, David Gerald TVR is indeed a small specialist outfit, but well established, knowledgeable and highly respected in TVR circles.

He has been an independent TVR specialist, based at Inkberrow in Worcestershire, for more years than I care to remember. He was appointed a TVR main dealer shortly before the company went belly-up, and I believe that these days he is a Marcos main dealer as well as retaining his trade in second-hand TVRs. He races a TVR Tuscan himself, with some success, so he's no novice when it comes to car handling and set-up.

I had dealings with him on several occasions when I owned a TVR Griffith, and found him honest and helpful.

Knowing these bushes are supplied by him (they must be manufactured elsewhere - I can't see David having acquired manufacturing facilities) certainly wouldn't put me off - quite the contrary!

[RotoFlexible]

I found a useful discussion of the pros and cons of poly bushings in this topic: http://www.lotuselan.net/forums/viewtopic.php?t=729. To summarize, it appears that poly bushings are less tolerant of imperfect alignment (i.e., they can bind if for some reason the bushing bores are not perfectly concentric around a single axis) and the length of the crush tube is critical. Too short, and the bushings will be captured by the washers that retain them and bind. The solution is to omit the washers and/or slacken the Nylocs - but I recommend reading the whole thread, it's interesting. All things considered, I will probably pull my NOS rubber bushings (for the front) out of storage and fit them instead, assuming they haven't deteriorated while on the shelf. I may get poly bushings for the rear, though.

[garyeanderson]

Poly bushes on the inner rear A arm and the bushings on the torque arms of the differential housing are a good move as the 90 wt. gear oil tends to make a good rubber bushing go bad (turns to goo) in time.

Gary

[oldokie]

Andrew, I hear the Chinese are dealing with the problem!

[RotoFlexible]

Andrew, I hear the Chinese are dealing with the problem!

You mean, the way they dealt with the food-and-drug problem?

[RotoFlexible]

The bushings I have on the shelf are not front A-arm bushings, I don't know what they are but I have eight of them. So I am getting a full set of the Autobush poly bushings. Once I have the car back on the road (shooting for October [2007]) I'll pass along my impressions.

[miked]

I found a useful discussion of the pros and cons of poly bushings in this topic: http://www.lotuselan.net/forums/viewtopic.php?t=729. To summarize, it appears that poly bushings are less tolerant of imperfect alignment (i.e., they can bind if for some reason the bushing bores are not perfectly concentric around a single axis) and the length of the crush tube is critical. Too short, and the bushings will be captured by the washers that retain them and bind. The solution is to omit the washers and/or slacken the Nylocs - but I recommend reading the whole thread, it's interesting. All things considered, I will probably pull my NOS rubber bushings (for the front) out of storage and fit them instead, assuming they haven't deteriorated while on the shelf. I may get poly bushings for the rear, though.

Andrew, I would not do the bit about "not fitting" the washers and slackening the nylocs. I am no expert but it sounds dangerous. I fitted these to an S4. I had some problems and there is more discusion (couple of years ago) on here.

With no washers you could migrate the front bones off the bushes. They are required. I found some of the bores of the bones too tight, thats why the crush tubes dont line up with the poly'. The poly swells outwards since it has no were to go. The nylocs must be tight against the washers/crush tubes. The poly is meant to move on the crush tube. Build your bones up without any shocker in and dog it all up. You should be able to work the suspension up and down on the tight assembley. If not, you have work to do. Find out what is causing it, top or btm bones and sort it out. Yes, they are less tolerent of out of shape bones with concetric misalignment with the bone tubes. I had some rubber bushes migrate to the washers and stop (thats why they are there). I found by accurate measurement the bones were all shapes. They were new. I sent them back from were they came with 8 pages of drawings showing how out of shape they were.

The new ones had to have slight reaming of the bones tubes but are fine. I have poly all aound. I make sure that with everything dogged up without any shockers they move freely.

There is more on the rear A frames and Poly' by by me on here. Again the A frames I got (new) were not the same dimensions as Lotus. Lots of filing later and they fit. They were Spyder. Very strong, lots of weld but all the bone tubes are longer. It matters not with rubber bushes as the are very forgiving. With poly all must be straight and the right sizes.

In my opinion TTR kit is best, very accurate and welds are perfection. I spent about 8 hours filing and lots of measuring to get poly' on the rear A frames when I removed my old Lotus ones that fitted with the poly.

Please have a search and read. Lot of arsing about over Xmas last year. I think I am no longer bothered about mentioning Spyder. Some good kit, some bad. Thats what the forum is for IMO, helping each other. Feedback helps them with their quality control. Tony may have some good turns of phrase etc, etc but his kit is very good.


Mike

[RotoFlexible]

Mike,

Thanks for the good advice. I am going to clean up the original rear wishbones this weekend and have a long hard look at them - measure the dimensions against the book dimensions and each other, check for twist and damage, etc. I plan to get some rod the same diameter as the bolts and pass it through the new bushings (when they arrive and when I get the old bushings out) then rig up some sort of alignment jig to make sure things are parallel.

Current plan of attack is Spyder non-adjustable in the front, top and bottom, and the original wishbones in the rear if they are fit. If not, I'll need to shop around. In light of your comments I'll take another look at what TTR has to offer.

I was already planning to set up the rear suspension without springs in order to check for CV joint binding at full droop. I'll do the same with the front and make sure the bushings are happy all around.

[RotoFlexible]

The photo shows the new Autobush front bushings fitted to new Spyder lower front arms. Getting the flange into the sleeve in the arm is a bit of a struggle - I had to poke it part way in with a screwdriver and then lean on the bushing until the flange fully popped into the sleeve. A light smear of the supplied grease inside the sleeve allows the bushing to slide into place easily.

I had to use a vice to get the crush tubes started into the bushings. You may be able to see that the end of the tube is flush on one side and about 1/16" recessed on the other. We'll see how this works out when assembled to the frame in a couple of weeks. If I use a washer with the nut, I'll smear some grease on the side of the washer that faces the bushing.

[gerrym]

Continuing with discussion re criticality of fit-up with poly bushes, I found that I had to use large INNER washers (between wishbone and chassis studs) to stop bushes migrating in that direction. Anyone else had the same problem?
Regards Gerry