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Star frame

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cwf
Posts: 81
Joined: Sat May 15, 2021 5:52 am

Star frame

Post by cwf »

Hello,

I have an R 35 with a pressed-steel frame, bought as a box of bits. Now I've got a complete final drive, I find the frame is bent. There's someone here in the UK who has straightened these frames before but he tells me it is going to be expensive, up to £1000. Someone else has told me it can cost Euro 2000 in Germany.

Has anyone been through this? Any advice? I have a spare crankcase and gearbox to make sure the final drive lines up.

Many thanks, Charlie.

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Darryl.Richman
Posts: 2091
Joined: Fri Oct 27, 2006 3:00 am

Re: Star frame

Post by Darryl.Richman »

It's possible to bend a frame into general position with various leverage tools (big crowbar, length of iron pipe, some chain, a scissors jack, etc.), but it's difficult to get it exactly right.

Someone who is really equipped with a massive table and various clamps and bars can make precise bends and get it exactly right. I think you're hearing numbers that are in the ballpark for this kind of work.

In my experience, you'll be much happier with the results a pro can provide. I've had bikes straightened both ways and I was much happier with the pro work.

(As a side note, but not meaning to be pedantic, these are actually Starr frame bikes. Starr is the German word for rigid, which makes a lot more sense than star does.)
--Darryl Richman

cwf
Posts: 81
Joined: Sat May 15, 2021 5:52 am

Re: Star frame

Post by cwf »

I certainly wasn't planning to try it myself - I've had enough tries in the past to know my limitations. In fact, I got the frame back two weeks ago and he'd made a good job of it. The headstock is now straight, I think the gearbox and final drive line up, the rear wheel spindle lines up both sides and the two wheels line up, and only £600. With all of 14 hp, I expect any small deviations will be lost in the general primitiveness.

His tools are basic : a straight bed and clamps, hydraulic rams, heat and measuring devices (and experience).

As far as the name of the frame goes, the Germans call them Starrahmen, which suggests Star and Rahmen, as the Germans don't mind having three identical letters when combining nouns. But you're right, starr means rigid or unbending, which I suppose is what they were compared to the earlier tube and brazed lug unless it was marketing speak.

Tinkertimejeff
Posts: 57
Joined: Thu Jan 20, 2022 5:49 pm

Re: Star frame

Post by Tinkertimejeff »

I know its a /2 frame straightening operation, it is always important to use the best most modern methods and tools when you are confronted with a bent frame.
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cwf
Posts: 81
Joined: Sat May 15, 2021 5:52 am

Re: Star frame

Post by cwf »

And the result was...?

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Darryl.Richman
Posts: 2091
Joined: Fri Oct 27, 2006 3:00 am

Re: Star frame

Post by Darryl.Richman »

I don't have any pictures, unfortunately, but a friend minorly crashed his RT here and he got it "straight enough" with chains, a come along and a scissors jack, which is what I had laying around. He used a couple posts in my garage to brace against. The photos from TinkertimeJeff are even more rustic, but instantly made me think of this episode. After that, I'm still convinced I did the right thing when I took my R52 frame to a guy with a huge steel table, many clamps and blocks, and various lever arm tools. He got everything straight enough that I've ridden it about 15k miles on 3 different Cannonball events.
--Darryl Richman

Tinkertimejeff
Posts: 57
Joined: Thu Jan 20, 2022 5:49 pm

Re: Star frame

Post by Tinkertimejeff »

My results with the Rat Ride were very good, the rear fender fit like a glove and not OJ's glove. I can now comfortably continue to build my "conversion reverse restoration".

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